US20070187844A1 - Electronic assembly with detachable components - Google Patents

Abstract

The present invention provides systems and methods for assembling an electronic assembly using an anisotropic conducting membrane (ACM) as a component interconnect and a substrate embossed with placement cavities or a positional fixture to facilitate component placement on the substrate in the electronic assembly. The fixture may comprise multiple layers of interconnects to improve routing density for the electronic assembly enclosed in a housing. An alignment chain may be used to monitor positional and contact integrity of the ACM interfaced components in a complex assembly. The systems and methods allow components to be detached for reuse. Interconnection elements or conduction pathways at the components can be used to interconnect a plurality of neighboring substrates over the ACM layers into a stacked electronic assembly.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation-in-part of U.S. patent application Ser. No. 11/351,418 entitled “Apparatus and Method for Predetermined Component Placement to a Target Platform,” filed Feb. 10, 2006, which is hereby incorporated by reference.
BACKGROUND
• 1. Field of the Invention
• The present invention relates generally to electronic assemblies, and more particularly to assembly techniques on the use of anisotropic conducting material as a component interconnect and the use of substrate embossed with placement cavities or the use of positional fixtures to facilitate the placement of component on the substrate in an electronic assembly.
• 2. Related Art
• Electronic assemblies are typically assembled by using surface mount technology (SMT), or more recently, the chip-on-board (COB) technology. Using SMT, packaged electronic components are soldered on a substrate, such as a printed circuit board (PCB), by printing a thin layer of solder paste on the substrate and following a thermal reflow process to solder the component to the substrate. Using COB technology, thin metal wires are attached or bonded to a bare die on a substrate to create a wire-bonded assembly. A layer of resin may then be applied to the surface of wire-bonded component to protect the bonded wires from being damaged in the assembly.
• One problem with both the SMT and the COB technique is that a soldered or wire-bonded component is typically difficult to remove for repair or reuse once it is attached to the substrate. At motherboards, sockets are often used for the installation of CPU chips to simplify its replacement or upgrade. The sockets are rather expensive. Therefore, there is a need for assembly techniques that allow components to be easily detached from the substrate for rework, reuse, or even replacement.
SUMMARY
• The present invention addresses the above problems with an assembly technique, which uses anisotropic conducting membrane (ACM) at a component interconnect interface and uses a substrate with embossed cavities or with an aligning fixture to facilitate the assembly of components on substrate in an electronic assembly. The aligning fixture comprises openings at predetermined spatial regions in the fixture. The embossed cavity on the substrate or the opening at the fixture is chosen in such a way that it enables a contact array of a component to match a designated land pattern on a substrate when the component is placed at the cavity or opening. The embossed cavities on the substrate or the openings in the fixture can also hold ACM interfaced components in place on the substrate after the components are placed. The ACM layer electrically connects component to the substrate and enables component to be readily detached for reuse or replacement. An ACM layer may be directly laminated at a component surface. Alternatively, the ACM layer may be placed at the substrate surface during the assembly process.
• An alignment chain can monitor the positional and contact integrity for a group of components on a substrate in an electronic assembly. By incorporating conductive pads as alignment marks at predetermined regions in a component and incorporating conductive pads as reference marks at designated regions on the substrate to match the positions of alignment marks at the component to be placed on the substrate, an alignment chain can be built. The alignment chain is formed by linking the alignment marks at a group of components with the matching reference marks on the substrate over an ACM interconnect layer from component to component to create a serial, continuous conduction path among the group of components to be monitored. Depending upon the complexity of the electronic assembly, the alignment chain may be divided into multiple smaller alignment chains to detect the positional and contact integrity for a smaller group of components linked in a chain by monitoring its conduction status. The technique allows components to be detached for reuse.
• In different embodiments of the invention, an electronic assembly may stack multiple substrates into a more compact three-dimensional structure. Interconnection elements can be used to facilitate the interconnection between neighboring substrates in a stacked assembly. The interconnection element comprises a pre-fabricated conductive path or routing trace in a planar structure or package for insertion into a fixture opening or an embossed cavity on the substrate to interconnect neighboring substrates across ACM layers. The interconnection elements can replace expensive socket, mechanical connector, or flexible ribbon circuit with minimal positional constraint on the substrate to simplify the design of an electronic assembly.
• The electronic assembly may be sealed in a housing, such as a plastic housing in a flash card, to hold the ACM interfaced components in place. The inner surface of the housing may be molded to match a height profile of the components. The housing may be in a form that can be open for component access, such as a heat spreader used in a memory module. The housing may comprise contacts or openings allowing an alignment chain to be monitored from the housing.
• Some exemplary methods of using anisotropic conductive material in an electronic assembly are illustrated. One exemplary method uses a substrate comprising embossed cavities to facilitate the placement of components and an anisotropic conducting membrane at the embossed cavity as a component interconnect layer to the substrate. The ACM may be directly laminated at the component interconnect surface to eliminate the ACM insertion step in manufacturing the electronic assembly. An alternative exemplary method is the use of an aligning fixture in the electronic assembly. The aligning fixture can be aligned to a substrate by using a placement equipment and bonded to the substrate by using anisotropic conductive paste or solder paste, if the fixture also contains an interconnect circuitry. Alternatively, a sheet of ACM may be placed on the substrate surface prior to the placement of the fixture. Both the embossed cavities on the substrate and the openings at the fixture can hold components on the target land patterns at the substrate with accuracy. Alignment marks or alignment mechanism may be incorporated in the fixture to align with matching reference marks or reference mechanisms at the substrate, although an optical pattern recognition technique may be used to align fixture to substrate.
• Benefits of exemplary implementations of the invention include the use of the ACM layer to replace solder paste or wire-bonding in a conventional component assembly. By using ACM as a component interconnect layer and using a fixture or embossed cavity at the substrate, components can be readily removed and reattached to an electronic assembly. Components that are expensive or in short supply can be readily detached and reused in different electronic assemblies. Defective components may be easily removed at rework. Furthermore, components can be detached and replaced in a system upgrade. This flexibility results because the ACM layer allows components to be readily detached and reattached in an electronic assembly without necessitating desoldering or cutting wire-bond that may damage the component or other parts of the assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 illustrate a set of alignment marks at a component coupled to a set of reference marks on a substrate with auxiliary conduction pathways, in an exemplary implementation;
• FIG. 2 depicts an exemplary implementation of an alignment chain linking two components on a substrate using anisotropic conducting membrane as an interconnect layer;
• FIG. 3 is depicts an enclosed electronic assembly comprising an alignment chain, in an exemplary implementation of the invention;
• FIG. 4A depicts a profile of an exemplary electronic assembly using a fixture to assemble components on a substrate enclosed in a housing;
• FIG. 4B depicts a top view of an exemplary fixture comprising interconnection traces and coupled to a substrate underneath;
• FIG. 5 depicts an exemplary electronic assembly of a memory module, where a fixture is attached to a substrate to hold the ACM interfaced components in place enclosed in a housing;
• FIG. 6 depicts a top view of a memory module including a fixture, components, an alignment chain, and an external interface enclosed in a clamshell according to an exemplary implementation of the invention;
• FIG. 7 depicts a flowchart of an exemplary method for assembling ACM laminated components on a substrate embossed with placement cavities in an exemplary assembly enclosed in a housing;
• FIG. 8 depicts a flowchart of an exemplary method for assembling an electronic assembly using ACP and ACM combined techniques; and
• FIG. 9 depicts an exemplary stacked assembly comprising multiple MFSs in a cascade.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
• Detailed descriptions of exemplary embodiments are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ embodiments of the present invention in virtually any appropriately detailed system, structure, or manner.
• An exemplary embodiment is an electronic assembly comprising detachable components assembled on a substrate via an anisotropic conductive material as an interconnect layer. The electronic assembly may comprise alignment chains to monitor positional and contact integrity of components on the substrate across the interconnect layer comprising the anisotropic conductive material.
• Electronic assemblies, such as flash cards, add-on boards, or memory modules, have components soldered or wire-bonded on substrate, which makes the components difficult to remove or reuse. The anisotropic conductive material can replace solder paste or wire-bonding in conventional electronic assemblies. The anisotropic conductive material conducts electric current in a specific direction and is suitable as an interconnect layer between the components and the substrate. Two forms of anisotropic conductive material can be used in an electronic assembly. One is an anisotropic conducting membrane (ACM), and the other is an anisotropic conductive paste (ACP). The ACM can be attached to, or removed from, a substrate surface. The ACM can also be attached to the component interface surface directly. The ACP is in paste format that can be printed and/or dispensed on an aligning substrate surface. The ACP is typically a material including a conductive filler and binder. As an example, the conductive filler is gold plated resin balls, and the binder is synthetic rubber in a thinner. The binder is capable of bonding two or more articles together using the ACP as an interconnect material after the curing of paste.
• It is useful to have electronic assemblies comprised of detachable components. For example, components that are expensive or in short supply can be readily detached from one electronic assembly and reused in a different electronic assembly. Defective components may also be removed easily at rework. Furthermore, a component may also be detached and replaced by a higher performance one in system upgrade. This flexibility results because the ACM layer allows component to be detached without necessitating desoldering or removing wire-bond that may damage the component or other parts of the electronic assembly.
• It is also useful to have a method for monitoring and diagnosing the positional and contact integrity of detachable components in an electronic assembly. One or more alignment chains may be incorporated in the assembly for such a purpose. In exemplary embodiments, an alignment chain is built by incorporating a set of alignment conductive pads, namely alignment marks, at predetermined regions in a component, and a set of matching reference conductive pads, namely reference marks, at designated locations on a substrate for detecting the placement integrity of the component on the substrate, wherein the alignment marks of the component and the matching reference marks on the substrate are linked from component to component in a serial, continuous, conduction path zigzagging between the component and the substrate over the ACM layer for a group of components on the substrate. Depending upon the complexity of the electronic assembly, the alignment chain may be divided into multiple smaller alignment chains to detect positional and contact integrity for a smaller group of components linked in the chain by testing its conduction status.
• FIG. 1 illustrates a set of alignment marks in a component and a set of matching reference marks on a substrate with an ACM interconnect layer in between. An alignment mark is a conductive contact region or a conductive pad on the component configured for aligning the component or for monitoring the positional and contact integrity of the component on the substrate. An alignment mark may be at a top surface or a bottom surface of the component. The alignment mark at the top surface of the component is named as a direct alignment mark, and the alignment mark at the bottom surface of the component is named as an indirect alignment mark. The direct alignment mark may be directly accessed for probing while the indirect alignment mark may be indirectly accessed for probing after the component is placed on the substrate. The direct alignment mark may be further connected to the bottom surface of the component through a conduction pathway to be in contact with the ACM layer.
• The indirect alignment mark makes a direct contact with the ACM layer. The indirect alignment mark may be connected to other indirect alignment mark through a conduction pathway on the same component. The indirect alignment mark on the component may be indirectly accessible over the ACM layer through a separate conduction pathway connecting to a probing point on a substrate surface beyond the component. The component may be an integrated circuit, a packaged device, a stacked device, a sensor, or an electro-mechanical element. For the packaged device, the alignment mark may be built in the package without actual connection to a circuit inside the package. For example, for a bare die, the alignment mark can be built in a die scribe line or within a die area.
• InFIG. 1, acomponent100 comprises adirect alignment mark110 and two indirect alignment marks120 and130. In exemplary embodiments, thedirect alignment mark110 may be in contact with anACM layer140 at acontact region111 through aconduction pathway115. The two indirect alignment marks120 and130, both in contact with theACM layer140, are connected together through aconduction pathway125. Theconduction pathways115 and125 and the alignment marks110,120, and130 illustrated inFIG. 1 are examples and are not to be construed as an exhaustive list of possible alignment marks and conductive pathways.
• FIG. 1 also illustrates a coupling between thecomponent100 and asubstrate150 through theACM layer140. Asubstrate surface145 comprises reference marks160,170, and180. A reference mark is a conductive pad or a contact region on thesubstrate surface145 configured to align with a corresponding alignment mark on thecomponent100. In exemplary embodiments, spatial locations for a set of reference marks (e.g.,160,170 and180) to a land pattern on thesubstrate150 should match the spatial locations of a set of alignment marks (e.g.,110,120 and130) to a contact array on thecomponent100. As a result, aligning the set of alignment marks (e.g.,110,120 and130) at the component to the set of reference marks (e.g.,110,170 and180) on the substrate can detect if the contact array at thecomponent100 is accurately and properly positioned on the land pattern atsubstrate150 after thecomponent100 is placed. InFIG. 1, thereference mark160 is configured to align with thealignment mark110, thereference mark170 is configured to align with thealignment mark120, and thereference mark180 is configured to align with thealignment mark130. The reference marks illustrated inFIG. 1 are examples and are not to be construed as an exhaustive list of possible reference marks.
• FIG. 2 depicts an exemplary diagram of anelectronic assembly200 including an alignment chain. Twocomponents210 and220, twoACM layers230 and240, asubstrate250, and analignment chain245 are shown in an exemplary implementation. Thecomponents210 and220 are coupled to thesubstrate250 via the ACM layers230 and240, respectively. Thecomponent210 comprises two direct alignment marks201 and202 at a top surface, which are further connected by way of twoconduction pathways203 and204 to make contact with theACM layer230 atbottom contact pads205 and206 of thecomponent210. Through the ACM layers230, the alignment marks201 and202 are able to make contact withreference marks233 and234 at asubstrate surface242 if thecomponent210 is aligned on thesubstrate250 correctly. Theconduction pathways203 and204 allow the placement and contact condition of thecomponent210 on thesubstrate250 to be probed from a componenttop surface208. Aconduction pathway207 links the bottom contact points205 and206 associated with the alignment marks201 and202 to form part of thealignment chain245 at thecomponent210.
• Thecomponent220 comprises two indirect alignment marks215 and216 at a bottom surface. In exemplary embodiments, the indirect alignment marks215 and215 are inaccessible from a top of thecomponent220. Aconduction pathway217 links the two indirect alignment marks215 and216 to become part of thealignment chain245. To access theindirect alignment mark216 at thecomponent220 over theACM layer240, aconduction pathway238 is incorporated at thesubstrate250 with one end-point connecting to areference mark237 at thesubstrate surface242 and the other end-point connecting to a probingregion239 also at asubstrate surface242. To access theindirect alignment mark215 over theACM layer240, aconduction pathway235 is incorporated at thesubstrate250 where one end-point is connected to areference mark236 and the other end-point is connected to areference mark234 to become part of thealignment chain245. The indirect alignment marks are useful in the alignment chain formation.
• TheACM layer230 and240 is configured to replace solder paste or wire bond in theelectronic assembly200. TheACM layer230 and240 conducts current in a specific direction, which is vertical in this case. TheACM layer230 and230electrically interconnects component210,220 tosubstrate250 but without conducting electrical current to neighboring regions within the ACM layer. The ACM layer enables component to be readily attached and detached from the substrate surface.
• Reference marks231,233,234,236,237, and239 are prefabricated on thesubstrate surface242, where the reference marks233 and234 are for the placement of thecomponent210, the reference marks236 and237 are for the placement of thecomponent220, and the reference marks231 and239 are for probing the integrity of thealignment chain245.
• As thecomponents210 and220 are properly aligned on thesubstrate250 through the ACM layers230 and240, acontinuous alignment chain245 is formed in a serial, continuous, conductive path jig-jagging between thecomponents210 and220 and thesubstrate250 across the ACM layers230 and240. Thealignment chain245 originates from a probing point (e.g., reference mark231) at thesubstrate250, through aconduction pathway232 linking to thereference mark233, then across theACM layer230 to the matching bottom surface contact-point205 at thecomponent210, then through aconduction pathway207 at thecomponent210 to a differentsurface contact point206, then across theACM layer230 again back to thesubstrate250 connecting to thereference mark234, through aconduction pathway235 continuing to thereference mark236 devised for thesecond component220, then over theACM layer240 coupling to theindirect alignment mark215 at thecomponent220, through aconduction pathway217 at thecomponent220 to theindirect alignment mark216 on thesame component220, over theACM layer240 again back to thesubstrate250 at thereference mark237, where it is coupled to theend probing point239 associated with the aligningchain245 through aconduction pathway238 at thesubstrate250. Theconduction pathways232,235, and238 may be embedded in thesubstrate250 or fabricated at thesubstrate surface242. In case thecomponent210 or220 is deviated from its target position at thesubstrate250, or there is a poor contact condition between thecomponent210 or220 and thesubstrate250, the alignment mark atcomponent210 or220 will no longer be in line with, or in contact with, its corresponding reference mark at thesubstrate250. No conduction status will be detected from the end points (e.g.,231 or239) of the alignment chain.
• Theconduction pathways232 and238 appended to the end ofalignment chain245 provideaccess points231 and239 for testing the integrity of thealignment chain245 in theassembly200. In various exemplary embodiments, a ground or power connection may be inserted in thealignment chain245 to split it into two separate, shorter alignment chains. The connection to ground or power creates a new end point for the split alignment chain. Components in an assembly can also be divided into several sub-groups to form several alignment chains. Multiple alignment chains are more effective in localizing displaced components in the assembly because a smaller alignment chain may encompass a smaller number of components in a localized area in an electronic assembly. Multiple test points can also be inserted to a large alignment chain along the conduction pathway or at the component to monitor the conduction status between any two test points.
• Passive components, such as resistors, capacitors, inductors, and other small outlined devices, which are typically low in cost or small in physical dimension, may be embedded in thesubstrate250 during the substrate fabrication (e.g., as embedded capacitors and embedded resistors) or soldered at thesubstrate surface242 in the electronic assembly manufacturing.
• An enclosure or protective structure, such as a plastic housing or a heat spreader, may be used to hold the ACM interfaced components in place in an electronic assembly. With the inclusion of the alignment chain in the assembly, the positional and contact status of the components enclosed in the protective structure, which may not be accessible from outside, can be monitored and detected through an alignment chain. Besides directly measuring the conduction status of the alignment chain by applying voltage source and ground to the end points of alignment chain respectively, various methods can be used to monitor the placement integrity of components at the alignment chain. For example, if a sensing device is attached to a connection point in the alignment chain, which may be on the substrate surface or may be incorporated at the component, then the positional and contact integrity for the group of components along the alignment chain can be detected easily by monitoring the status in the sensing device. As an example, the sensing device may be a latch in a component with a connection to an alignment mark accessible by the component. By applying a signal from one end-point of the alignment chain and monitoring the status of the sensing device at the component, the integrity of alignment chain from the one end-point to the component comprising the sensing device can be readily determined. By toggling the signal applied to an end-point of the alignment chain, the sensing device or latch at the component along the alignment chain can be monitored to determine whether or not it toggles accordingly. If not, a bad contact or displaced component along the alignment chain in an electronic assembly is thus identified.
• FIG. 3 depicts a diagram showing an exemplary implementation of the invention, which comprises a solder-free electronic assembly in an enclosure with a built-in alignment chain. The example illustrates a set ofcomponents302,304, and306, connected to asubstrate314 throughACM layers308,310, and312, housed in a protective covers316 and318 in anelectronic assembly300.Openings320 and322 at thetop cover316 may be provided for accessing the probing points (e.g.,alignment mark324 and contact point326) of analignment chain328 to observe positional and contact integrity for the set ofcomponents302,304, and306 on thesubstrate314. Thealignment chain328 in theassembly300 originates at thealignment mark324 of thecomponent302, zigzags through theACM layer308, thesubstrate314, and theACM layer308 again to thecomponent302, then through theACM layer308 again back to thesubstrate314. Thealignment chain328 continues to thecomponent304 through theACM layer310, through thecomponent304 and through theACM layer310 again back to thesubstrate314, then throughACM layer312 to thecomponent306, back to thesubstrate314 through theACM layer312 and ends at thecontact point326. One end point of the alignment chain328 (e.g., contact point326) may be coupled to ground, shown in dotted line to simplify diagnosis connection. In this case, theopening322 at thetop cover316 is not required. One opening at the top cover matching a location of the other end-point is sufficient. The opening at thetop cover316 for accessing the end-point of thealignment chain328 may be replaced by a built-in conduction pathway within thecover316 if a proper contact can be insured, such as applying an ACM layer in between. In an alternative approach, no opening in the cover is required if the end points of the alignment chain are accessible from the external interface pads of the electronic assembly (e.g. by multiplexing the end points of alignment chain with the functional pins of the electronic assembly).
• FIG. 3 also shows a set of matching notches being incorporated at an edge of the top and bottom covers316 and318 to hold the assembly in place when thecovers316 and318 are clipped on. Aninner surface330 of thetop cover316 may be embossed in a topology with thickness variations matching the height variations ofcomponents302,304, and306 in theassembly300 to hold thecomponents302,304, and306 in place. Elasticity of theACM layer308,310, and312 may provide contact pressure after the clipping of thecovers316 and318. AlthoughFIG. 3 only shows one side of thesubstrate314 assembled with thecomponents302,304, and306, it is applicable to an electronic assembly having both sides of thesubstrate314 populated with components.
• In various embodiments of the invention, to facilitate the placement of components on a substrate and to hold components in place in an electronic assembly with ACM as an interconnection layer, a positional fixture comprising pre-fabricated openings to match physical outlines of the components to be placed on the substrate may be included in the assembly. A set of alignment marks may be comprised within the fixture to align with a set of reference marks on the substrate so that a contact array at a component can be placed accurately on a target land pattern at the substrate if the set of alignment marks at the fixture is properly aligned to the set of reference marks on the substrate. The fixture can be attached, clipped, or glued on the substrate surface, according to exemplary embodiments, after it is properly aligned to the substrate.
• In yet another embodiment of the invention, the set of openings at the fixture may be directly embossed at the substrate surface during substrate fabrication to become a set of embossed cavities on the substrate. Nevertheless, an inserted fixture is more adaptive than an embossed one. For example, the physical outline of many comparable memory chips, such as gigabit DRAM or Flash, may be varied from semiconductor company to company due to variations in the IC fabrication process. A more advanced process can yield a packaged chip in a smaller physical outline. However, pin location and pin pitch associated with the contact array of comparable memory chips are mostly the same to ensure interchangeability in manufacturing. An inserted fixture is more adaptive than the embossed one to meet manufacturing needs.
• FIG. 4A illustrates a profile view of an exemplary implementation of the invention using afixture410 for assembling a set ofcomponents402,404, and406 onto asubstrate420 in anelectronic assembly400 enclosed incovers450 and455. Thefixture410 comprisesopenings422,424, and426 matching physical outlines of thecomponents402,404, and406, respectively. Theopenings422,424, and426 are pre-fabricated at specific positions so that thecomponents402,404, and406 along withACM403,405, and407 as interconnect layers can be placed accurately on corresponding land patterns at a substrate surface. A set of alignment marks412 and414 are incorporated at thefixture410 with matching reference marks413 and415 at the substrate surface for aligning thefixture410 to thesubstrate420. Thefixture410 is aligned to thesubstrate420 by aligning the alignment marks412 and414 to the matching reference marks413 and415. Thecomponents402,404, and406 may then be placed at theopenings422,424, and426. The alignedfixture410 is able to holdcomponents402,404, and406 accurately on the corresponding target land patterns at the substrate surface.
• The thickness of thefixture410 is comparable to a lowest component height. Inner surfaces of thecovers450 and455 may be embossed in a topology matching a height variation of thecomponents402,404, and406 to be assembled. Alternatively, a layer ofthermal membrane440 and445 may be inserted between thecomponents402,404, and406 and thecovers450 and455 if thethermal membrane440 and445 is thick enough to serve as a buffer to press the ACM interfaced components in place. Thethermal membrane440 and445 may also transfer heat generated by thecomponents402,404, and406 to the cover surface.
• Various approaches can be used to align thefixture410 to thesubstrate420. For example, thefixture410 can be aligned to thesubstrate420 mechanically by incorporating a set of mounting holes as mechanic alignment marks at thefixture410 and a set of mounting cylinders as a mechanical reference marks at thesubstrate420, or vice versus with mounting cylinders at thefixture410 and mounting holes at thesubstrate420. According to some embodiments, the alignedfixture410 is adhered to the substrate surface with paste, glue, a clamp, or a screw after thefixture410 is aligned to thesubstrate420. The final assembly is then enclosed in a housing comprising a set ofcovers450 and455. Thecovers450 and455 may comprise one ormore contact openings420 or contact pads for external interfacing use or for monitoring the contact status of analignment chain428.
• InFIG. 4A,top notches452 and454 on thetop cover450 are configured to couple withbottom notches456 and458 on thebottom cover455 to hold theelectronic assembly400 securely after thecovers450 and455 are pressed together. Thetop notches452 and,454 and thebottom notches456 and458 may be two parallel slits along an edge of thecovers450 and455. The shapes of the notches depicted inFIG. 4A are intended as illustrative and are not to be construed as the only possible shape of the notches or the only possible way of sealing. For example, thetop cover450 and thebottom cover455 may be sealed by using ultrasonic welding technique or by using clips if there are no notches or matching slits to hold thecovers450 and455 together. The assembly technique shown inFIG. 4A is applicable to flash card assembly, memory card assembly, and consumer electronic product assembly in various embodiments.
• FIG. 4B depicts a top view of thefixture410 placed on thesubstrate420. Another embodiment of the invention is the incorporation of interconnect circuitries at thefixture410 so that thefixture410 not only serves as a position holder for the ACM interfaced components but also comprises interconnect circuitries for the components in the electronic assembly. Passive components can also be pre-fabricated, incorporated, or embedded within thefixture410.FIG. 4B illustrates exemplary interconnection traces464 and465, via466, andconductive pads467 for external access embedded in thefixture410. The interconnect traces464 and465 at thefixture410 and the interconnect traces at thesubstrate420 comprise a complete set of interconnect circuitry for the electronic assembly through the ACM layer underneath thefixture410. Thefixture410 may be a single-layer fixture or a multiple-layer fixture comprising more interconnection layers for a higher routing density and a better signal integrity.
• The alignment chain in an electronic assembly can incorporate the fixture as part of the alignment chain by adding conduction alignment marks and conductive pathways to the fixture and linking these marks and pathways with the alignment marks and conductive pathway at the components, and the matching reference marks and conduction pathways at the substrate into a serial continuous conduction path to detect the positional and contact status of the components and the fixture on the substrate. One or more end points of the alignment chain can be made accessible outside the cover to detect the integrity of the alignment chain.
• In an assembly process, the ACM layer can be coupled to the component using one of several techniques. For example, the ACM layer can be attached to a surface of a packaged device, a bare die IC, or a stacked device prior to being placed in the assembly. Alternatively, a pre-carved ACM layer can be inserted into an opening at the fixture embossed or already attached to the substrate surface prior to the placement of the components. In yet another embodiment, an ACM layer is placed on the substrate surface prior to the placement of the fixture on the substrate, after which the components are placed on the substrate using the fixture as a guide.
• When ACP is used in the manufacturing processes, a thin layer of ACP is dispensed or printed on the substrate surface. Components are directly aligned and placed on the land patterns at the substrate surface without the use of the fixture. A plate or cover may be used to hold the aligned components in place, follows a curing and heat pressing process to attach the components securely onto the substrate.
• In another embodiment of the invention, an ACM and ACP combined technique can be used in the electronic assembly, in which ACP is used to bind the fixture onto the substrate, and ACM is used as the component interconnect layer. A component using ACM as the interconnect layer can achieve good contact and can be easily detached from the substrate surface for reuse.
• In various exemplary embodiments of the invention, two or more fixtures can be used in an electronic assembly to ease assembly and rework process. For example, a first fixture can be configured to align and hold a first subgroup of components, and a second fixture can be configured to align and hold a second subgroup of components (e.g., the remaining components). Some exemplary embodiments comprise an electronic assembly in which components are placed on both surfaces of the substrate. In such embodiments, one or more fixtures can be used to align and hold the components coupled to the first substrate surface and one or more additional fixtures can be used to align and hold the components coupled to the second substrate surface. Multiple fixtures are useful in a large electronic assembly to cope with thermal expansion deviation between the fixture and the substrate, if any, and to ease the rework.
• FIG. 5 depicts an exemplary assembly of the invention, such as a memory module or an add-on board, where afixture510 is attached to asubstrate520 to hold ACM interfacedcomponents501,502,503,504,505, and506 in anelectronic assembly500 surrounded by protective housing, such as a pair ofclamshells560 and570. In this embodiment of invention, thefixture510 may be embossed on the substrate surface to become a plurality of embossed openings on the substrate, or thefixture510 may be coupled to thesubstrate520 during the assembly process. The protective housing, for example, may be a heat spreader comprising the twoidentical clamshells560 and570 and twoidentical clamps561 and562. Along a long edge of theclamshells560 and570 there is amale notch563 and573 and afemale notch564 and574 being bent at a right angle toward an inner surface of theclamshells560 and570. In alternative embodiments, theclamps561 and562,male notches563 and573, andfemale notches564 and574 may not need to be identical.
• During assembly, thecomponents501,502,503,504,505, and506 are placed atopenings511,512,513,514,515, and516 of thefixture510 after thefixture510 is aligned and attached to thesubstrate520. Then the assembledsubstrate containing fixture510 andcomponents501,502,503,504,505, and506 is placed on the inner surface of one clamshell (e.g.,560). Taking the second clamshell (e.g.,570) and rotating it by 180 degree so that itsmale notch573 andfemale notch574 are able to be inserted into the matingfemale notch564 andmale notch563 of thefirst clamshell560. Flipping and closing the twoclamshells560 and570, the assembled substrate can be sandwiched between two inner surfaces of theclamshells560 and570. Attaching theclamps561 and562 to a top edge of theclosed clamshells560 and570, the ACM basedcomponents501,502,503,504,505, and506 can be held steady inside thefixture openings511,512,513,514,515, and516 in theelectronic assembly500.Thermal membranes565 and575 may be attached to the inner surface of theclamshells560 and570. The elasticity of thethermal membranes565 and575 is able to press components in good contact with thesubstrate520. Thethermal membrane565 and575 is adaptive to a minor height variation amongcomponents501,502,503,504,505, and506 on thesubstrate520, if any. The contact integrity of the ACMinterconnected components501,502,503,504,505, and506 on thesubstrate520 in an enclosed assembly can be monitored with one or more alignment chains linking components in a serial connection with access points either incorporated from the surface of theclamshell560 or570, or connected to anexternal interface connection530 or an exposed substrate surface.
• FIG. 6 depicts a top view of anexemplary memory module600 comprising elements similar to those ofFIG. 5. Thememory module600 is housed in aclamshells630. Theclamshell630 functions as a protective device, a component retaining device, and a heat dissipation device for a group of components assembled in thememory module600. In the exemplary illustration, thememory module600 comprises afixture610 on aPCB substrate620. One ormore fixtures610 may be attached to a surface of thePCB substrate620 to support a one or two sided PCB assembly. Memory components ordevices601,602,603,604, and605 and supportinglogic device606, such as clock chip, register chip, buffer chip, or an integration of these logic functions, using ACM as an interconnect layer over thePCB substrate620, are then placed at theopenings611,612,613,614,615, and616 of thefixture610 and retained by a set ofclamshell630 housing withclamps632 and634 clipped on a top edge of theclamshell630. Theclamps632 and634 are configured to couple with theclamshell630 to hold the memory assembly tightly within theclamshell630. Although only one supportinglogic device606 is shown, a memory module may include more than one supporting logic devices. In exemplary embodiments, the memory device may comprise a dynamic random access memory device, static random access memory device, flash memory device, electric erasable programmable memory device, programmable logic device, ferromagnetic memory devices, or any combination of the above.
• In the exemplary illustration, analignment chain625 links the memory components and the supporting logic devices for checking contact integrity of the memory components and logic devices along thealignment chain625 in thememory module600, where one end-point626 of thealignment chain625 may be tied to ground and another end-point627 is assessable from a substrate surface, according to one embodiment. The end-point627 may be further coupled to apin628 at an external interface region630 (i.e., gold finger) to be directly accessible by a motherboard or main-board after thememory module600 is inserted into a socket in the motherboard. In another embodiment, bothend points626 and627 of thealignment chain625 may be connected to the pins at theexternal interface region630 of thememory module600 accessible by a motherboard or for further coupling to other alignment chains in the motherboard. Sensing device, such as latch, can be attached to the component along the alignment chain to monitor the integrity of the alignment chain. Thealignment chain625 is an optional feature in thememory module600 implementation using ACM as the component interconnect layer.
• FIG. 7 depicts a flowchart of an exemplary method for assembling an exemplary electronic assembly enclosed in a housing. The electronic assembly is similar to theassembly400 inFIG. 4A with a number of simplifications. For example, in the exemplary flowchart a substrate surface is embossed with cavities for guiding placement of components, instead of using a fixture. In addition, an ACM layer is laminated at a component surface, instead of using a separate ACM layer placed between the component and the substrate. The cavities embossed on the substrate surface can have accuracy compatible to PCB fabrication process in a range of a few mils, where a mil is a thousandth of an inch. In addition, only one side of the substrate is assembled with components in the exemplary embodiment ofFIG. 7, although both sides of the substrate can be assembled with components. To improve manufacturing quality and throughput, an assembly fixture may be used in a surface mount equipment to facilitate assembly of multiple electronic assemblies at a time.
• FIG. 7 begins instep710, in which a housing cover (e.g., a bottom cover) is placed in an assembly fixture. It should be noted that only one electronic assembly is discussed inFIG. 7 since the same procedure can be repeated several times if more than one electronic assembly is to be assembled in parallel.
• After the bottom cover is placed in an assembly fixture, a thermal membrane may be placed over the bottom cover instep720. The thermal membrane is an optional bill of material, depending upon heat generation and requirements of mechanical supports in the final electronic assembly. Instep730, a substrate comprising embossed cavities is placed on the bottom cover including the optional thermal membrane. Then depending upon the assembly method instep740, ACM laminated components can be inserted at embossed openings manually instep750, or with placement equipment instep755. After the component placement, a thermal membrane or elastic laminar may then be placed on the assembled substrate instep760 to improve thermal dissipation and to press the ACM laminated components to make good contact with the substrate after placing a top cover to temporarily enclose the assembly instep770. Alternatively, a thermal membrane or elastic material may be pre-laminated at the inner surface of the cover to eliminatesteps720 and760 in the assembly method.
• After the top cover is positioned to temporarily enclose the electronic assembly, testing is conducted instep780 to determine whether or not the assembly is properly assembled. If it is not properly assembled as determined instep785, then a rework is carried out instep790 to remove the top cover and to diagnose misplaced components or poor contact components to fix the problem. The top cover is then replaced and the assembly is retested instep780. If the assembly passes the test, then the housing is securely sealed, such as by applying ultrasonic welding to seal top and bottom covers, to form the electronic assembly.
• FIG. 8 is a flowchart depicting an exemplary method for assembling an electronic assembly using an ACP and ACM combined technique, where ACP is used to bind a fixture (namely a component fixture) on a substrate surface, and ACM is used as an interconnect layer between components and a substrate so that the components can be readily inserted or detached from a substrate surface without use of solder paste as in conventional assemblies. The substrate is electronically coupled or interconnected to the components via the ACM layer and to the component fixture via the ACP layer. Serial alignment chains can be embedded in the assembly to monitor positional and contact integrity of the components. Similar to the embodiment inFIG. 7, a number of electronic assemblies can be assembled in parallel under pick-and-place surface mount equipment. To simplify depiction, only one electronic assembly is discussed in the method ofFIG. 8.
• At the beginning of assembly, an ACP layer is dispensed or printed on the substrate surface with a paste pattern specific for the component fixture to be placed instep810. Conduction traces can be fabricated at the component fixture as part of interconnection circuitry in the electronic assembly.
• The component fixture is aligned and placed on the substrate surface dispensed with a layer of ACP instep820. The ACP should be thick enough to bind the component fixture securely on the substrate surface after curing of paste. The component fixture may be aligned to the substrate surface by aligning a set of alignment marks on the fixture to a set of target reference marks on the substrate, optically or electrically. Alternatively, the fixture can be aligned to the substrate surface mechanically by using a pair of mechanical structures, such as mounting holes on the fixture and mounting cylinders on the substrate, or vice verse.
• Instep830, hot pressing and curing of the ACP is performed to attach the fixture to the substrate. Hot pressing and curing of the ACP also results in an anisotropic electrical conduction in a direction of pressing (i.e., from the fixture to the substrate).
• A test is conducted instep840 to determine if the fixture is properly assembled on the substrate. If the fixture is not properly assembled, the fixture is either discarded or reworked instep845, depending upon if the substrate or fixture has considerable value or how complicated it is in rework. If the cured fixture passes the test (i.e., it is well aligned to the substrate), then the ACM layer and component are placed at a target opening in the component fixture until all components are placed instep850.
• The opening in the fixture not only holds the component on the substrate accurately, but also ensures a contact array at a component package is in contact with a component's target land pattern fabricated on the substrate surface if the component is properly pressed from the top. The size of the fixture opening should match a dimensional outline of the component but still allow the component to be inserted and removed with ease. The ACM layer is suitable for components in a land grid array (LGA) package where no solder ball is attached to the package except in an array of bare contacts.
• After placing components at the fixture openings with the ACM as the interconnect layer, a cover comprising a layer of elastic material on an inner surface, such as a thermal membrane, is then placed on top of the assembly to hold components in place in the fixture openings instep860. A test is performed instep870 to check if the components are properly assembled. If test fails, the cover is removed to reposition the displaced components or to replace a bad ACM membrane or a defective ACM laminated component instep885. The process (i.e., steps860-885) is repeated until the test is passed instep880. Then, the electronic assembly comprising the top and the bottom covers is clamped, clipped, latched, or sealed to hold all components securely in the electronic assembly instep890.
• If both sides of the substrate are to be populated with components, then the one-side assembled substrate including bottom cover can be turned over after passing the test instep880, and then steps810 to880 may be repeated to place a second fixture, ACM layers, and the components at a second surface of the substrate until the second side is fully assembled with components and passes the test.
• In another embodiment of the invention, a second substrate may be used to facilitate the assembly of an electronic assembly with components assembled on both sides. After the assembled substrates pass test, the first assembled substrate and the second assembled substrate may be aligned and placed back to back with an anisotropic conducting membrane (ACM) in between to form a double-sided electronic assembly. If no electric connection is required between the first and the second substrates, a thermal membrane, paste, or glue may be used instead of the ACM.
• In various embodiments of the invention, multiple fixtures, multiple ACMs, and multiple substrates may be stacked into a three dimensional (3D) structure to increase the integration density of an electronic assembly comprising detachable components, where the detachable component may be laminated with a separate ACM layer at its interface, or a separate ACM layer may be inserted at the interface between the component and the substrate underneath it. The combination of the ACM layer, the fixture, the ACM laminated or interfaced components at a fixture opening, and the substrate constituents a basic building block, namely a basic MFS (Membrane-Fixture-Substrate) configuration, for the construction of a stacked electronic assembly illustrated, for example, inFIG. 9. AnACM layer915,925, and935 may be replaced by a thermal membrane, if the MFS basic building block does not electrically interface with other MFS configurations in the stacked assembly. The stacked assembly may be further enclosed and sealed in a housing, in some embodiments.
• FIG. 9 is an exemplary embodiment of an assembly comprising threestacked MSF configurations910,920, and930 in cascade. In this embodiment, the stacked MSFs are back to back and do not require a gap in between, so the components to the ACM layer or the thermal membrane also do not require a gap. The gaps shown inFIG. 9 are only for distinguishing the building blocks and associated constituents more clearly. A set of mounting holes and mounting cylinders may be used to align and to bind the multiple MFSs.
• For each MFS, the ACM layer at the top can serve as an interconnect layer to the neighboring MFS at its top. To facilitate interconnection between neighboring MFSs, in various embodiments of the invention, a set of interconnect elements comprising conductive pathways or connection traces can be pre-fabricated as chips or planar elements for insertion into the fixture openings to connect the MFS to a neighboring MFS. The interconnect element functions as a connector connecting substrates at two neighboring MFSs through the ACM layers. The interconnect element can replace expensive mechanical connector, such as a Mictor connector, and a flexible circuitry seen in the electronic assemblies. There is an additional advantage for the interconnect element coupled with the ACM layer. The number and the locations of interconnect elements can be chosen freely within a fixture without the physical or location constraints encountered by the mechanical connectors or the flexible circuitries. Since both sides of substrate may be fabricated with interconnect circuitry to increase routing density, the interconnect elements provide needed interconnections between two neighboring substrates through the ACM layers. The passive components in an electronic assembly can be embedded in the fixture, embedded in the interconnect element, or solder mounted on the substrate surface in the MFS. Alternatively, aconductive pathway942 associated with an alignment mark running from top to bottom in a component to be placed at the MFS can be used as an interconnection element between two neighboring MFSs through the ACM layers. Similarly, aconduction pathway944 associated with reference mark running from top to bottom in a substrate can also be used as a connection for the neighboring MFSs.
• An alignment chain is useful for diagnosing the positional and contact status of components in an electronic assembly comprising more complex structure, such as one with multiple stacked MFSs. The alignment chain is an optional feature for a simple electronic assembly, as the functional test may be adequate to determine if the ACM based component is properly assembled. But for a complex electronic assembly, an efficient way to identify the defective block is essentially to lower the test, debug, or rework costs. The alignment chain is a solution for a complex electronic assembly comprising a large number of detachable components or multiple MFSs. An alignment chain that links the conductive alignment marks for a group of components and the matching conductive reference marks at substrate into a serial conductive pathway is effective in detecting the assembly integrity for the group of components in the assembly. Multiple alignment chains divide the components in a complex electronic assembly into multiple sub-groups with access points attached to each smaller alignment chain to detect the positional and contact status of the ACM interfaced components segregated in a smaller region in the electronic assembly.
• The present invention has been described with reference to exemplary embodiments. It will be apparent to those skilled in the art that various modifications may be made and that other embodiments can be used without departing from the broader scope of the present invention. For example, some electronic assemblies may comprise one or more alignment chains as well as one or more fixtures that may further comprise multiple layers of interconnect under various housings or enclosures. Therefore, these and other variations upon the exemplary embodiments are intended to be covered by the present invention.

Claims (53)

1. An electronic assembly, comprising:

a component comprising a contact array for external interfacing;

a substrate comprising a set of land patterns configured to match the contact array of the component; and

an anisotropic conducting material (ACM) layer configured to electrically couple the component to the substrate.

2. The electronic assembly ofclaim 1, wherein the component further comprises a set of conductive pads coupled to the contact array, the conductive pad coupled to a conductive pathway configured to conduct a signal from one surface region to another surface region of the component.

3. The electronic assembly ofclaim 2 wherein the conductive pad is further coupled to a sensing device at the component.

4. The electronic assembly ofclaim 1, wherein the substrate further comprises a set of conductive pads coupled to the set of land patterns on the substrate.

5. The electronic assembly ofclaim 4, wherein a conductive pad of the substrate is coupled to a conductive pad on the component to monitor placement integrity of the contact array of the component over the ACM layer on the land pattern at the substrate, where the conductive pad on the component is an alignment mark and the conductive pad on the substrate is a reference mark.

6. The electronic assembly ofclaim 1, wherein the contact array is a set of conductive pads on the component for external interfacing.

7. The electronic assembly ofclaim 1, wherein the ACM layer is laminated on the component and is configured to allow the component to be detached from the substrate.

8. The electronic assembly ofclaim 1, wherein the ACM is laminated on a surface region of the substrate.

9. The electronic assembly ofclaim 1 further comprising at least one thermal membrane configured to provide thermal dissipation for the component.

10. The electronic assembly ofclaim 1 further comprising an alignment chain coupling the conductive pads of a group of components with matching conductive pads of the substrate over the ACM layer in a serial continuous conductive path.

11. The electronic assembly ofclaim 10, wherein the group of components can be further divided into a number of smaller groups of components to form multiple alignment chains in the electronic assembly.

12. The electronic assembly ofclaim 10, wherein the alignment chain is configured to diagnose positional and conduction status for the group of components on the substrate over the ACM layer.

13. The electronic assembly ofclaim 10 further comprising a set of access regions for monitoring integrity of the alignment chain.

14. The electronic assembly ofclaim 1 further comprising a protective structure configured to hold the component in place on the substrate.

15. The electronic assembly ofclaim 14, wherein the protective structure comprises one or more covers having an inner surface configured to match a height profile for the component placed on the substrate.

16. The electronic assembly ofclaim 14, wherein the protective structure comprises a housing to hold the component and the substrate in place, the housing comprising:

a top cover comprising a set of top notch; and

a bottom cover comprising a set of bottom notch, the bottom notch configured to couple to the top notch to hold the housing together.

17. The electronic assembly ofclaim 14, wherein the protective structure comprises a clamshell housing for holding the component and the substrate, the clamshell housing comprising:

a top plate coupled to a top notch;

a bottom plate coupled to a bottom notch, the bottom notch configured to be coupled with the top notch; and

a clamp configured to be applied to hold the top plate and the bottom plate together.

18. The electronic assembly ofclaim 1, further comprising at least one fixture configured to facilitate placement of the component using an anisotropic conducting membrane as an interface layer.

19. The electronic assembly ofclaim 18, wherein the fixture comprises a plurality of openings matching a physical outline of the component being placed on the substrate.

20. The electronic assembly ofclaim 18, wherein the fixture comprises one or more interconnect layers with interconnect circuitry to facilitate routing of signals between the component and the substrate.

21. The electronic assembly ofclaim 18, wherein the fixture comprises a plurality of embedded passive components.

22. The electronic assembly ofclaim 8, wherein the fixture is embossed on a surface of the substrate.

23. The electronic assembly ofclaim 18, wherein the fixture is coupled onto a surface of the substrate by an anisotropic conductive membrane.

24. The electronic assembly ofclaim 18, wherein the fixture is coupled and cured onto a surface of the substrate by an anisotropic conductive paste.

25. The electronic assembly ofclaim 18, wherein the fixture is soldered onto a surface of the substrate by a solder paste.

26. The electronic assembly ofclaim 18, wherein the fixture is mechanically coupled to an aligning surface of the substrate by incorporating a set of mounting holes to match a set of mounting cylinders to hold the fixture in place on the substrate.

27. The electronic assembly ofclaim 18, wherein the fixture is mechanically coupled to an aligning surface of the substrate by incorporating an indent at a surface of the substrate to hold the fixture in place on the substrate.

28. The electronic assembly ofclaim 18, wherein the fixture comprises a set of conductive pads configured to align with a set of conductive pads at the substrate for detecting placement integrity of the fixture on the substrate.

29. The electronic assembly ofclaim 28, further comprising an alignment chain coupling the conductive pads coupled to conductive pathways at the fixture with the conductive pads coupled to conductive pathways at the substrate over an anisotropic conductive material.

30. The electronic assembly ofclaim 1, wherein the electronic assembly is a memory module, comprising:

one or more memory devices on the substrate, wherein the memory devices receive signals over a memory bus for accessing the one or more memory devices;

at least one fixture (comprising a set of openings) configured to position the one or more memory devices on the substrate using an anisotropic conducting material as an interface layer; and

a protective structure to hold the one or more memory devices on the substrate.

31. The electronic assembly ofclaim 30, further comprising one or more logic devices that receive control signals over a memory bus for access the one or more logic devices.

32. The electronic assembly ofclaim 30, wherein the memory devices are selected from one of the followings:

dynamic random access memory device;

static random access memory device;

flash memory device;

electric erasable programmable memory device;

programmable logic device;

ferromagnetic memory devices; and

any combination of above.

33. The electronic assembly ofclaim 30, further comprising an alignment chain of for diagnosing the placement integrity of the memory devices.

34. The electronic assembly ofclaim 1, wherein the component may comprise a plurality of components.

35. The electronic assembly ofclaim 34, wherein components of the plurality of components may be positioned on one or more surfaces of the substrate.

36. The electronic assembly ofclaim 1, wherein the substrate comprises a plurality of substrates.

37. The electronic assembly ofclaim 1, wherein the ACM layer comprises an anisotropic conducting membrane.

38. The electronic assembly ofclaim 1, wherein the ACM layer comprises an anisotropic conducting paste.

39. A method for assembling an electronic assembly, comprising:

coupling an anisotropic conducting material (ACM) layer onto a surface of a substrate; and

positioning a component over the ACM layer such that a contact array of the component is in alignment with a corresponding land pattern on the substrate to form the electronic assembly.

40. The method ofclaim 39, further comprising placing a thermal membrane on top of the component to dissipate heat and to provide mechanic support for the component on the substrate within a protective structure.

41. The method ofclaim 39 further comprising housing the electronic assembly within a protective structure.

42. The method ofclaim 39 further comprising testing the electronic assembly to determine if the component and substrate are properly aligned.

43. The method ofclaim 42 further comprising repositioning the component if the component and substrate are not properly aligned.

44. The method ofclaim 39 further comprising aligning and coupling a fixture to the substrate.

45. The method ofclaim 44 wherein the aligning comprises aligning at least one alignment mark of the fixture to at least one reference mark of the substrate.

46. The method ofclaim 44 wherein the aligning comprises aligning at least one mounting hole of the fixture to at least one mounting cylinder of the substrate.

47. The method ofclaim 44 wherein the coupling comprises curing and press heating the fixture to the substrate.

48. The method ofclaim 39 wherein positioning the component comprises aligning at least one alignment mark of the component with at least one reference mark of the substrate.

49. An electronic assembly, comprising:

an anisotropic conducting material (ACM) layer coupled onto a surface of a substrate; and

means for positioning a component over the ACM layer such that a contact array of the component is in alignment with a corresponding land pattern on the substrate in the electronic assembly.

50. An electronic assembly in a stacked configuration, comprising:

a plurality of substrates;

a plurality of fixtures comprising placement openings;

a plurality of ACM membranes; and

a plurality of ACM interconnected components at the placement openings.

51. The electronic assembly ofclaim 50, wherein the ACM membrane, the substrate, the fixture, and the ACM interconnected components placed at the placement openings of the fixture form a MFS (Membrane-Fixture-Substrate) building block, and are configured so that a plurality of MFS building blocks are stacked in cascade coupled with interconnect elements.

52. The electronic assembly ofclaim 51, wherein the interconnect element is a conduction pathway connecting from a top surface to a bottom surface of the component.

53. The electronic assembly ofclaim 51, wherein the interconnect element is a planner passive comprising a set of conduction pathways connecting from a top surface to a bottom surface of the planner passive.

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