US20140333505A1 - Semiconductor package having integrated antenna pad - Google Patents

Abstract

An apparatus for a semiconductor-package includes a semiconductor device having a radio frequency (RF) input or output, an antenna pad, and a package structured to house the semiconductor device and the antenna pad. The antenna pad may be coupled to the radio frequency (RF) input or output, and the antenna pad is structured to reduce the inductance of the package. The antenna pad may include a pad disposed above the semiconductor device, a pad disposed to a side of the semiconductor device, or an antenna chip. An antenna may be coupled to the antenna pad. The antenna may include a trace antenna, a staggered antenna, or a helical antenna.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of U.S. patent application Ser. No. 12/062,482, filed Apr. 3, 2008, now U.S. Pat. No. 8,791,862, issued Jul. 29, 2014, which is a continuation of U.S. patent application Ser. No. 10/861,714, filed Jun. 4, 2004, now U.S. Pat. No. 7,369,090, issued May 6, 2008, which claims priority to U.S. Provisional Patent Application No. 60/476,350, filed Jun. 4, 2003, and which is a continuation-in-part of U.S. patent application Ser. No. 10/147,827, filed May 17, 2002, now U.S. Pat. No. 6,914,566, issued Jul. 5, 2005, which claims priority to U.S.Provisional Patent Application 60/291,721, filed May 17, 2001, all of which are incorporated by reference herein in their entirety.
TECHNICAL FIELD
• This disclosure relates generally to packaged semiconductor devices, and, in particular, to Ball Grid Array (BGA) packages for wireless devices.
BACKGROUND OF THE INVENTION
• Allowing devices to connect to computers through a wireless communication path and wirelessly networking groups of computers is one of the fastest growing segments of the PC industry. Present and emerging standing technologies in this field include IEEE 802.11 (versions a, b and g) also known as ‘WiFi’ available from (# sign used to prevent automatic hyperlinks)
• http:#standards.ieee.org#catalog#olis#lanman.html, ‘Bluetooth’ available from https:#www.bluetooth.org and Cypress Semiconductor's proprietary WirelessUSB standard available from http:#www.wirelessusb.org.
• Ball Grid Array (BGA) packaging technology is a popular choice for packaging semiconductor devices, or “chips,” because BGAs offer advantages in space, cost and density over other packaging technologies. This is also true for semiconductor devices pertaining to wireless communications. Wireless devices tend to be quite sensitive to inductance, however, and it is advantageous to minimize the effects of inductance when designing, manufacturing and using wireless and other sensitive devices.
• Aconventional BGA package10 is shown inFIG. 1. Thispackage10 includes one or more devices orintegrated circuits12, aBGA substrate14,mold compound16,gold wire20 for wire bonds,epoxy resin22 to adhere thedevices12 to thesubstrate14, and solder-balls24 to make electrical connections to a circuit board (not shown), such as a line or slot card in a computer or other device. Theconventional BGA package10 may pick up inductance from its connections, for example where abond wire20 connects to a pad on thedevice12, and through a trace to aball24 which connects to a board which connects to an antenna (e.g., an antenna attached to the line card). This electrical path can pick up inductance, and negatively effect the performance of the device. Excess inductance limits the range of transmitting and receiving the wireless signals, and reduces quality of service (QOS) of wireless devices.
• Embodiments of the invention address these and other limitations in the prior art.
SUMMARY OF THE INVENTION
• According embodiments of the invention, a BGA package including an integrated antenna is described. This improved BGA package has a lower inductance than a conventional BGA package.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a cross-sectional view of a conventional BGA package.
• FIG. 2 is a perspective view of a BGA package having an integrated a peripheral trace antenna according to embodiments of the invention.
• FIG. 3 is a perspective view of a BGA package having an integrated staggered peripheral trace antenna according to other embodiments of the invention.
• FIG. 4 is a perspective view of a BGA package having a pad antenna mounted separate from a die, according to yet other embodiments of the invention.
• FIG. 5 is a perspective view of a BGA package having a pad antenna mounted to the side of a die on a BGA substrate according to still other embodiments of the invention.
• FIGS. 6A and 6B are a schematic block diagrams illustrating inductances of a conventional package solution and a package solution according to embodiments of the invention, respectively.
DETAILED DESCRIPTION
• Embodiments of the invention are directed toward a package, such as a BGA package that includes a connection for an antenna that is also connected to the package. The antenna may be incorporated directly on a BGA substrate. In these ways, less inductance appears in the antenna path and antenna circuits are more efficient than is otherwise presently possible.
• Present wireless communication devices include a radio incorporated on an integrated circuit chip. Antennas are used to transmit and receive the wireless signals. Antennas are implemented as conductive lengths of material having a variety of shapes to optimize reception and transmission properties. As a general rule, antenna lengths range from a half wavelength to under one tenth wavelength of the transmitted or received signal, depending upon the antenna configuration and the level of acceptable performance. Space must be allocated to accommodate the antenna and allow for adequate transmission and reception.
• An exemplary embodiment of a BGA package according to embodiments of the invention is described with reference toFIG. 2. This figure illustrates a perspective view of aBGA package40 having an antenna traced, formed, produced, or otherwise attached directly on asubstrate42 of theBGA package40 itself. A circuit having a radio frequency (RF) input or output, or both is located in a circuit on adie50. In one embodiment theantenna44 may be coupled to apad52 on thedie50, while in other embodiments theantenna44 may be coupled to a pin orball56 or other connection on thewireless package40. The purpose of connecting thetrace antenna44 in this manner is to lower the series inductance between the RF circuit and its associated antenna, to reduce the overall inductance seen by the device, and to improve performance. Lowered inductance by using embodiments of the invention can lower insertion loss in the antenna system on the order of 1 or more dB's by reducing the number of connections the signal must travel through between the RF circuit on thedie50 and theantenna44.
• In one embodiment theantenna trace44 may travel around the periphery of thedevice40, but in other embodiments the trace may be laid elsewhere on device. In some embodiments, theantenna44 may have an impedance matched to the atmospheric impedance.
• The RF circuit on the die50 may be a receiver or transmitter for any wireless technology. In particular, the wireless communications devices formed on the BGA40 may include IEEE 802.11, HomeRF, Bluetooth, and other devices using the 2.4 GHz Industrial, Scientific, and Medical Band (ISM). The devices may also operate at frequencies below or above the ISM band. The circuit to which theantenna44 is attached may be used in devices such as mobile phone handsets, personal data assistants, palmtops, pocket personal computers, printers, scanners, digital cameras, game consoles, MP3 players, wireless network access points, and the like.
• Theantenna44 may be constructed in whole or in part from solder and/or other electrically conductive material that is adhesive, printable, patternable, sprayable, or meltable. Theantenna44 may be entirely constructed from a length of solder and/or other electrically conductive material which is shaped into a desired pattern—serpentine, straight length, branched, etc. This process may entail melting the material or using a resist for patterning on theBGA substrate40. Troughs having conductive surfaces or surfaces which collect and adhere flowable material may be disposed throughout or selectively dispersed on theBGA substrate40, or, as described below, other circuit boards or other suitable surface so as to collect and hold the liquefied conductive material before it hardens. When solder and solder balls, which may be used to produce theantenna44, are molten, they may cause a beneficial self centering effect on the integratedcircuit package40 through surface tension effects. Alternatively, theantenna44 may be formed by spraying an adhesive, electrically conductive material through a mask. Theantenna44, if formed from a length of solder and/or other electrically conductive material, may be disposed upon the circuit board or the IC chip package. The application of flowable materials, such as solder, to form theantenna44 should be well controlled, because applying too much, too little, or irregularly to form theantenna44 may affect its radiation and pickup patterns from one manufactured antenna to the next. Precise control of the processing is important in manufacturing the antennas as well as the other components.
• Various electrically conductive materials may be used to form theantenna44. For instance, theantenna44 may be formed, at least in part, from a metal, such as copper, aluminum, nickel, bismuth, tungsten, silver, palladium, platinum, zinc, chromium, molybdenum, lead, antimony, tin, or gold, or a non-metallic conductive material, such as poly silicon. If solder material is used, it may contain two or more of the group consisting of lead, bismuth, tin, antimony, copper, silver, zinc, and indium and may be lead free, such as tin-silver solder or tin-indium solder. Different lengths of the antenna may be formed of different materials. For example, if theantenna44 is partly formed in theintegrated circuit50, partly formed through interconnection elements such as bonding wires, and partly formed on theBGA substrate40, theantenna44 may have a polysilicon section, a solder material section, a gold wire section, and a copper section to maximize space utilization in the device. Material characteristic matching may be applied to improve the antenna performance.
• Dielectric material, such as a liquid epoxy resin, may be disposed or filled around the interconnection elements which form theantenna44 to reduce the overall length of theantenna44, since coating theantenna44 elements with a higher permittivity (i.e., dielectric) material may help capture RF energy for theantenna44. The dielectric material may be applied in flowable form on theBGA substrate40 by an applicator and then hardened by heat or other radiation. The dielectric material may be formed through resists which are patterned or etched. A consideration in selecting dielectric material of a certain permittivity is that the higher the permittivity, the more RF energy is reflected within the antenna and the more narrow banded the resultingantenna44 performance. Alternatively, theantenna44 may be formed on a dielectric substrate, such as ceramic substrate separately attached to theBGA substrate40.
• Another embodiment of a BGA package according to embodiments of the invention is described with reference toFIG. 3. This figure is a perspective view of aBGA package60, similar to thepackage40 ofFIG. 2, except having anantenna44 that is shaped in a “staggered” configuration. As before, theantenna44 is coupled to an RF input or output circuit on thedie50, and again theantenna44 may have an impedance matched to the atmospheric impedance.
• Having anantenna44 shaped in such a manner provides control to the fabricator over the overall length of theantenna44. As described above, different length antennas perform differently for particular electromagnetic frequencies. Having control over the length of theantenna44 allows the designer to select theappropriate length antenna44 for the particular desired application. The length of theantenna44 may be set for the center frequency of the operating band of the RF circuit on thedie50. Further,multiple antennas44 or antenna elements could be used to more precisely capture information contained in sub bands within the operating band. In some embodiments,multiple antennas44 may be placed on thesubstrate82 and may be switchably selectable.
• In this embodiment, theantenna44 may be coupled to apad52 on a die, and in other embodiments theantenna44 may be coupled to a pin orball56 or other connection on the wireless package.
• The shape of theantenna44 is not limited to the two shapes illustrated inFIGS. 2 and 3, but rather can take any form, shape, and/or orientation dependent on factors of application, performance, cost, etc. In some embodiments, theantenna44 may be a loop, patch, dipole, and other type of antenna, as is known in the art. Additionally, theantenna44 is not limited to single loop antennas, but may be practiced with a double loop, triple loop, or other types of loop antennas, including fractional loop antennas such as 1 and ¾ loop antennas. Embodiments of the invention are compatible with and capable of including patch or microstrip antennas, such as those described in U.S. Pat. No. 6.914,566.
• The area of theBGA substrate42 and thecircuit board50 where the antenna is disposed may be made so as to reduce or eliminate conductive elements which may interfere with the receipt or transmission of radio frequency energy. Also, it may be desirable to place theantenna44 at or near the edge of theBGA substrate42 to maximize the antenna's placement.
• FIG. 4 illustrates another embodiment of the invention. This figure is a cross sectional diagram of a BGA package having an integrated, stacked, antenna pad. In this embodiment, aBGA package80 includes aBGA substrate82 that provide support for one ormore devices86. As described above, a circuit on one or more of thedevices86 includes an RF input or output, or both. Thedevices86 are adhered to the substrate, typically by anepoxy resin84, and are surrounded bymold compound88. Electrical connections between thedevices86 and thesubstrate82 are formed throughwires90 and wire bonds. Also, as described above, pins orballs92 connect theBGA package80 to cards or other circuits.
• This embodiment additionally includes anantenna pad94 mounted on theBGA package80. Theantenna pad94 itself may be a surface mounted antenna chip or a conductive element which is flexibly bound and largely insulated by a carrier material which has an adhesive side or mechanically attachable portion. An antenna96 (not shown) may be integrated with, covered by, or attached to theantenna pad94. Theantenna pad94 is coupled to the RF input or output circuit on thedevice86 through aconnection wire98. The connection wire may be formed of the same material as thewires90, or could be a different material. The material may be selected for its antenna properties, as described above. In other embodiments, theconnection wire98 need not be a wire at all, but rather could be formed of a metal trace, film, solder bond, or other type of connection.
• Connecting the antenna pad94 (or antenna96 directly) through theconnection wire98 lowers the series inductance to the wireless device over conventional methods. This reduces the overall effect of inductance on the device.
• Theantenna pad94 andconnection wire98 may be covered by a protective coating to protect it while it is being handled, moved, etc. Such a coating may be particular to covering antennas, such as described above, and may be selected based on the RF properties as well as mechanical properties.
• The antenna96 may have an impedance matched to the atmospheric impedance. In other embodiments, thepad94 could be enclosed by themold compound88 of thedevice80. Further, thepad94 could be placed under thesubstrate82, or could be embedded as a plane within thesubstrate82. In yet other embodiments, thepad94 could be any shape or cover any portion of thedevice80, and thepad94 does not necessarily have to cover the majority of the device like shown inFIG. 4. All of these variations are specifically contemplated and envisioned as embodiments of the invention.
• FIG. 5 illustrates yet another embodiment of a BGA package according to embodiments of the invention. This embodiment is similar to the embodiment described above with reference toFIG. 4, and like reference numbers denote like elements. In this embodiment, theantenna pad94 is located to one side of the encapsulatedpackage100, rather than above thepackage80 as described with reference toFIG. 4. Theantenna pad94 may be attached to thesubstrate82, and may be directly coupled to thedevice86 through theconnection wire98. Theantenna pad94 situated such as illustrated inFIG. 5 enables a relatively easy connection of theconnection wire98. Also, as described above, theconnection wire98 need not be a wire, and could be a trace, film, or other method used to connect theantenna pad94 to thedevice86. Similar to as described above, theantenna pad94 may be covered by a coating for protecting thepad94 and theconnection wire98.
• Using techniques of embodiments of the invention taught with reference toFIGS. 4 and 5, embodiments of the invention can also include a helical antenna formed entirely within either a BGA package, such as those described in the aforementioned and incorporated US patent application Ser. No. 10/147,827.
• FIGS. 6A and 6B are schematic diagrams illustrating comparative inductances in prior art systems and those according to embodiments of the invention, respectively. With reference toFIG. 6A, a system120 includes aBGA package122 that has a die126 mounted thereon. The die includes an RF circuit, as described above. Aninductance128 is associated with a wire line that connects the die126 to the edge of the BGA package, for example to a pin or solder ball. Aninductance130 is associated with connecting anexternal antenna134 to the pin or solder ball. As referenced inFIG. 6A, the inductance can be on the order of 0.1 to 0.3 nH, which introduces excess inductance, insertion losses, and other poor performance of the antenna system.
• FIG. 6B is a schematic diagram illustrating an antenna system140 according to embodiments of the invention. The system140 includes aBGA package142, including adie146. Differently than in the system120 ofFIG. 6A, an antenna150 is coupled directly to thedie146, and does not travel through a separate pin or ball. This eliminates the effective series inductance (ESL) seen in prior art circuits that is associated with a pin or ball connection between a packaged die and the outside of the package. By removing this inductance, the performance of a wireless device may be improved.
• It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, it is emphasized and should be appreciated that two or more references to “an embodiment” or “one embodiment” or “an alternative embodiment” in various portions of this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the invention.
• Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Claims (20)

What is claimed is:

1. A device comprising:

a substrate;

an integrated circuit (IC) comprising a radio frequency (RF) circuit mounted on the substrate;

a compound encapsulating the IC;

a plurality of external contacts at least partially uncovered by the compound coupled to the IC;

an antenna pad located on the substrate coupled to the RF circuit; and

an antenna situated on the substrate coupled to the antenna pad.

2. The device ofclaim 1, wherein the external contact comprises one of a pin or a ball.

3. The device ofclaim 1, wherein the pad is part of the IC

4. The device ofclaim 1, wherein the RF circuit is configured to communicate using one of the 802.11 or Bluetooth standards.

5. The device ofclaim 1, wherein the antenna is configured to operate at a frequency higher than the 2.4 GHz ISM band.

6. The device ofclaim 1, wherein the antenna comprises electrically conductive material disposed on the substrate.

7. The device ofclaim 1, wherein the antenna is partly formed in the IC.

8. The device ofclaim 1, wherein the antenna is at least partly unencapsulated by the compound.

9. The device ofclaim 1, wherein the compound is located between the antenna and the substrate.

10. A method comprising:

mounting an integrated circuit (IC) comprising an RF circuit on a substrate;

encapsulating the IC with a compound;

coupling a plurality of external contacts to the IC, wherein the external contacts are at least partially uncovered by the compound;

coupling an antenna pad located on the substrate to the RF circuit; and

placing an antenna on the substrate and coupling the antenna to the antenna pad.

11. The method ofclaim 10, wherein coupling the plurality of external contacts to the IC comprises coupling the IC to one of a pin or a ball.

12. The method ofclaim 10, wherein coupling the antenna pad to the RF circuit comprises incorporating the pad as part of the IC.

13. The method ofclaim 10, further comprising configuring the device to communicate using one of the 802.11 or Bluetooth standards.

14. The method ofclaim 10, further comprising configuring the device to operate at a frequency higher than the 2.4 GHz ISM band.

15. The method ofclaim 10, wherein the placing of the antenna on the substrate comprises forming the antenna by depositing electrically conductive material on the substrate.

16. The method ofclaim 10, wherein encapsulating the IC with the compound comprises at least partly encapsulating the antenna.

17. The method ofclaim 10, wherein the placing of the antenna on the substrate comprises mounting the antenna on the compound.

18. A system comprising:

a circuit board;

a device mounted on the circuit board, the device comprising a substrate;

an integrated circuit (IC) comprising an RF circuit mounted on the substrate;

a compound encapsulating the IC;

a plurality of external contacts at least partially uncovered by the compound coupled to the IC;

an antenna pad located on the substrate coupled to the RF circuit; and

an antenna situated on the substrate coupled to the antenna pad.

19. The system ofclaim 18, wherein the system comprises a mobile phone handset.

20. The system ofclaim 18, wherein the system comprises a personal computer.

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