Disclosure of Invention
The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a processing alignment method of an HDI circuit board and the HDI circuit board, which can improve the processing alignment precision of the HDI circuit board.
In one aspect, an embodiment of the present invention provides a method for processing and aligning an HDI circuit board, including:
An inner layer circuit, namely processing a first circuit layer on an inner layer core plate and forming a process edge with a first metal target to obtain a first semi-finished product;
Laminating and drilling a target, namely processing a reference target hole on the basis of the first metal target at the process side of laminating the semi-finished product to obtain a second semi-finished product;
Drilling the second semi-finished product based on the reference target hole, and processing a first annular target with circumferentially distributed through holes at the process side to obtain a third semi-finished product;
a laminated circuit, wherein a second circuit layer and a second metal target are processed on the basis of the first annular target on the third semi-finished product, so as to obtain a fourth semi-finished product;
Lamination, namely re-drilling the reference target hole after lamination of the fourth semi-finished product to obtain a fifth semi-finished product;
A lamination blind hole is formed by windowing the fifth semi-finished product based on the reference target hole to expose the second metal target and the first annular target, and processing the blind hole by the second metal target to obtain a sixth semi-finished product;
drilling the sixth semi-finished product based on the reference target hole and penetrating through the center of the first annular target to form a first composite target, so as to obtain a seventh semi-finished product;
Repeating at least one of the laminated circuit, the laminated lamination, and the laminated drilling, the laminated blind hole and the laminated buried hole until the multi-layer processing is completed, wherein the reference target hole penetrates through all the laminated layers and serves as a unified alignment reference, and the first composite target of the previous process serves as an alignment reference of the laminated circuit of the subsequent process.
According to some embodiments of the invention, the processing of the first circuit layer and forming a process edge with a first metal target of the inner core board results in a first semifinished product comprising:
And processing a first circuit layer on the inner core plate based on the alignment function and the pre-given expansion coefficient of the direct imaging equipment and forming a process side with a first metal target to obtain a first semi-finished product.
According to some embodiments of the invention, the machining of the reference target hole on the basis of the first metal target at the process side of laminating the semi-finished product, to obtain a second semi-finished product, comprises:
performing alignment recognition on the first metal target based on an X-Ray alignment function of the laminated drilling target equipment;
And processing a reference target hole on the basis of the first metal target at the process side of laminating the semi-finished product to obtain a second semi-finished product.
According to some embodiments of the invention, the machining of the reference target hole on the basis of the first metal target at the process side of laminating the semi-finished product, to obtain a second semi-finished product, comprises:
and processing a plurality of reference target holes on the basis of the first metal targets at two oppositely arranged process sides of the laminated semi-finished product to obtain a second semi-finished product.
According to some embodiments of the invention, the drilling the second semi-finished product based on the reference target hole, and processing a first annular target with circumferentially distributed through holes at a process side to obtain a third semi-finished product, including:
and drilling the second semi-finished product based on the reference target hole, and processing a first annular target at the process side by adopting a minimum aperture to obtain a third semi-finished product, wherein the first annular target comprises a central through hole and a plurality of through holes circumferentially distributed around the central through hole.
According to some embodiments of the invention, the drilling the second semi-finished product based on the reference target hole, and processing a first annular target with circumferentially distributed through holes at a process side to obtain a third semi-finished product, including:
And drilling the second semi-finished product based on the reference target hole, and processing a first annular target on the process side based on the aperture of 0.2mm to obtain a third semi-finished product, wherein the first annular target comprises a central through hole and 16 through holes circumferentially distributed around the central through hole.
According to some embodiments of the invention, the drilling the sixth semi-finished product based on the reference target hole and penetrating the center of the first annular target to form a first composite target, obtaining a seventh semi-finished product, includes:
And drilling the sixth semi-finished product based on the reference target hole, and penetrating through the central through hole of the first annular target to form a first composite target, so as to obtain a seventh semi-finished product.
According to some embodiments of the invention, the drilling the sixth semi-finished product based on the reference target hole and penetrating the central through hole of the first annular target to form a first composite target, to obtain a seventh semi-finished product, includes:
Drilling the sixth semi-finished product based on the reference target hole;
and processing the central through hole of the first annular target into a through hole so as to form a first composite target, and obtaining a seventh semi-finished product, wherein the aperture of the through hole is larger than that of the central through hole and smaller than the inner diameter of the first composite target.
On the other hand, the embodiment of the invention provides a processing alignment method of an HDI circuit board, which comprises the following steps:
processing a first circuit layer on the inner core plate and forming a process edge with a first metal target to obtain a first semi-finished product;
Processing a reference target hole on the basis of the first metal target at the process side of laminating the semi-finished product to obtain a second semi-finished product;
drilling the second semi-finished product based on the reference target hole, and processing a first annular target with circumferentially distributed through holes at the process side to obtain a third semi-finished product;
Processing a second circuit layer and a second metal target on the third semi-finished product based on the first annular target to obtain a fourth semi-finished product;
re-drilling the reference target hole after laminating the fourth semi-finished product to obtain a fifth semi-finished product;
Windowing the fifth semi-finished product based on the reference target hole to expose the second metal target and the first annular target, and processing a blind hole by using the second metal target to obtain a sixth semi-finished product;
Drilling the sixth semi-finished product based on the reference target hole and penetrating through the center of the first annular target to form a first composite target, so as to obtain a seventh semi-finished product;
Processing a third circuit layer and a third metal target on the seventh semi-finished product based on the first composite target to obtain an eighth semi-finished product;
Re-drilling the reference target hole after laminating the eighth semi-finished product to obtain a ninth semi-finished product;
windowing the ninth semi-finished product based on the reference target hole to expose the third metal target, processing a blind hole by the third metal target, and processing a second annular target containing circumferentially distributed through holes at the process side to obtain a tenth semi-finished product;
drilling the tenth semi-finished product based on the reference target hole and penetrating through the center of the second annular target to form a second composite target, so as to obtain an eleventh semi-finished product;
and processing a fourth circuit layer on the eleventh semi-finished product based on the second composite target.
In still another aspect, an embodiment of the present invention provides an HDI circuit board, which is prepared by using the above processing alignment method for an HDI circuit board.
The embodiment of the invention has at least the following beneficial effects:
Meanwhile, based on the composite target (the structure after the through hole is formed in the center of the first annular target) generated in the previous working procedure as the alignment reference of the laminated circuit in the subsequent working procedure, the spatial correlation between the annular distribution through holes and the central through holes is utilized to respectively provide dual alignment references of radial distribution characteristics and central positioning characteristics, so that the positioning deviation of each laminated procedure only affects the current level, and the error is prevented from overlapping layer by layer to the subsequent working procedure. In addition, through the synergistic effect of the reference target hole and the composite target in the repeated processing process, the annular through hole of the composite target in the previous process provides a local compensation reference for the subsequent blind hole/buried hole processing, and the central through hole inherits the global positioning information of the reference target hole, so that layer-by-layer convergence of positioning errors is realized in the multi-layer stacking, and the processing alignment precision and the processing reliability of the HDI circuit board are improved.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
In the description of the present invention, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present invention and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention.
In the description of the present invention, the meaning of "a number" means one or more, the meaning of "a plurality" means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and "above", "below", "within", etc. are understood to include the present number. If any, the terms "first," "second," etc. are used for distinguishing between technical features only, and should not be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless explicitly defined otherwise, terms such as "disposed," "mounted," "connected," and the like are to be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by those skilled in the art in combination with the specific contents of the technical solutions.
The production process flow of the HDI circuit board is a high-complexity precise manufacturing process, and is characterized in that a high-density interconnection structure is realized, and key technologies such as micro-blind hole burying, laser drilling, multiple lamination and the like are involved. Because the whole production process flow of the HDI circuit board involves a plurality of steps, in order to focus on the technical purpose of this embodiment, the processing alignment accuracy of the HDI circuit board is improved, the core process directly related to the processing alignment accuracy is mainly analyzed, and other basic processes can refer to standard HDI process specifications, for example, inner layer circuit manufacturing includes material cutting and pretreatment, pattern transfer, browning/blackening treatment, inner layer AOI detection and the like.
Referring to fig. 1, the present embodiment discloses a processing alignment method of an HDI circuit board, including:
an inner layer circuit, namely processing a first circuit layer on an inner layer core board 101 and forming a process edge with a first metal target 201 to obtain a first semi-finished product 102;
For example, referring to fig. 2, the inner core board 101 is subjected to a pattern transfer process after being subjected to a material cutting and a pretreatment, and the purpose of the pattern transfer process is to process a line pattern on a metal layer on the surface of the inner core board 101 so as to form an inner circuit layer. The process side is an edge area reserved for facilitating processing and assembly of the HDI circuit board (production board) in the production process, and is not involved in circuit functions and mainly used for supporting, fixing and auxiliary production (such as alignment). When the inner core board 101 is subjected to pattern transfer processing, functional circuits (shown as a mark A1 in fig. 2) can be processed simultaneously and a first metal target 201 is processed at the process side, and the first metal target 201 is used as an alignment reference for the subsequent process.
Lamination drilling, namely processing a reference target hole 202 on the basis of the first metal target 201 while laminating the semi-finished product to obtain a second semi-finished product 103;
For example, when the lamination process is performed after the inner layer circuit is completed, the laminated material (such as resin coated copper foil, RCC) is laminated and pressed with the first semi-finished product 102 based on the first semi-finished product 102, as shown in fig. 3, the functional circuit (such as the mark A1) and the first metal target 201 shown on the left side in fig. 3 are covered with the laminated material to be invisible in a dotted line. It should be noted that the laminate material is pre-windowed by etching the copper foil before lamination to avoid the first metal target 201. The laminated semi-finished product is obtained after lamination treatment, the first metal target 201 is detected by utilizing the characteristic that X-rays penetrate through a resin layer of the laminated material, the first metal target 201 is used as an alignment reference, a reference target hole 202 (shown on the right side of fig. 3) is processed on the process side of the laminated semi-finished product, and the aperture and the hole position can be determined according to actual design requirements. The process can be performed by adopting lamination X-ray drilling and targeting integrated equipment so as to reduce alignment errors and shorten process conversion time so as to improve processing efficiency.
Drilling the lamination, namely drilling the second semi-finished product 103 based on the reference target hole 202, and processing a first annular target 203 containing circumferentially distributed through holes at the process side to obtain a third semi-finished product 104;
Illustratively, the laminated semi-finished product (i.e., the second semi-finished product 103) needs to be subjected to a drilling process after the lamination process is completed to form a through-hole on the laminated semi-finished product as a foundation for burying the hole. The lamination drilling process drills the second semi-finished product 103 with the reference target hole 202 as a registration reference, as shown by A2 on the left side of fig. 4. The first annular target 203 is synchronously processed at the process side in the drilling process, the first annular target 203 comprises a plurality of through holes distributed circumferentially, and the alignment error of a single point can be reduced through coordinate interaction of discrete hole sites, so that higher alignment precision is provided for subsequent laminated circuit manufacturing.
Processing the second circuit layer and the second metal target 204 on the third semi-finished product 104 based on the first annular target 203 to obtain a fourth semi-finished product 105;
The fabrication process of the laminated circuit is similar to the fabrication process of the inner circuit, except that the fabrication of the laminated circuit uses the first annular target 203 as an alignment reference and performs alignment detection by using an image visual detection technique. The first annular target 203 has higher alignment precision, and the first annular target 203 is obtained by processing the reference target hole 202 as an alignment reference, and by inheritance of the alignment reference, the alignment accumulated error can be reduced, and the alignment precision is improved. When the third semi-finished product 104 processes the second metal line (as indicated by A3 in fig. 4), the second metal target 204 is processed synchronously, so as to be used as an alignment reference for the subsequent process.
Lamination, namely, re-referencing the target hole 202 after lamination of the fourth semi-finished product 105 to obtain a fifth semi-finished product 106;
For example, lamination is a lamination and lamination process of laminating the laminate material with the fourth semi-finished product 105, and the HDI circuit board may be fabricated by performing multiple lamination and drilling operations, each of which may involve the fabrication of a target hole. In order to ensure the accuracy of the entire manufacturing process, a series of measures are generally taken to ensure the position and accuracy of the target hole. Such measures may include the use of high precision positioning equipment, tight process control and quality control, etc . The second metal line (shown as A3) shown on the left side in fig. 5, the second metal target 204, the first annular target 203 and the reference target hole 202 are all covered by the laminated material in dotted lines, and the reference target hole 202 is electroplated with metal after the processing of the laminated line to form a metallized through hole, so that the laminated material can be repositioned in the same manner as the laminating and drilling process, that is, the laminated material needs to be pre-windowed by etching copper foil before lamination.
A lamination blind hole, namely, windowing the fifth semi-finished product 106 based on the reference target hole 202 by laser to expose a second metal target 204 and a first annular target 203, and processing the blind hole by the second metal target 204 to obtain a sixth semi-finished product 107;
illustratively, after lamination is completed, both the second metal target 204 and the first annular target 203 are covered by the laminate material, and the first annular target 203 is changed from a through-hole target to a blind-hole target. Referring to fig. 5, the fifth semi-product 106 is laser windowed by a laser drilling device with the reference target hole 202 as an alignment target, so as to ablate copper foil and resin material on the surfaces of the second metal target 204 and the first annular target 203, thereby exposing the second metal target 204 and the first annular target 203. It should be noted that, after the electroplating treatment in the laminated circuit procedure, the through hole of the first annular target 203 may form a metallized hole, and after the laser windowing treatment, the first annular target 203 may be exposed. In the current processing technology, the size of the blind hole is smaller, and laser equipment is generally adopted for processing. After exposing the second metal target 204, the second metal target 204 is used as an alignment reference to process the blind hole, as shown by a symbol A4 in fig. 5, so as to ensure alignment accuracy between the blind hole processing and the circuit pattern of the upper layer.
Drilling the sixth semi-finished product 107 based on the reference target hole 202 and penetrating through the center of the first annular target 203 to form a first composite target 205, so as to obtain a seventh semi-finished product 108;
For example, lamination burial is typically performed by mechanical drilling to form a through hole in the lamination blank (i.e., sixth blank 107) that may be subsequently laminated and bonded to become burial. The stacked buried holes are drilled in the sixth semi-finished product 107 with the reference target holes 202 as alignment references to form through holes as indicated by reference A5 in fig. 6. During the drilling process, a through hole is simultaneously machined in the center of the first annular target 203 (alignment mark of the previous process) to form a first composite target 205. The first composite target 205 can be matched with the alignment degree of the through hole and the blind hole, the first composite target 205 can be compatible with material expansion and contraction of the previous process mark in the pressing/processing process, superposition errors are automatically homogenized through geometric center constraint, and by utilizing the spatial superposition characteristics of the first composite target 205, the historical processing errors (expansion and contraction deformation of the first annular target 203) and the processing positioning (through holes) of the current layer are vector synthesized, alignment error convergence of the process stage is realized through center superposition, and higher-precision alignment reference is provided for the subsequent process.
Repeating the lamination line, lamination, and at least one of lamination drilling, lamination blind hole and lamination buried hole until the multi-layer processing is completed, wherein the reference target hole 202 penetrates all the lamination layers and serves as a unified alignment reference, and the first composite target 205 of the previous process serves as an alignment reference of the subsequent process lamination line.
For example, according to the different layers of the HDI circuit board, the laminated circuit between different laminated layers and the processing technology of lamination are similar, the difference is that the adopted alignment references are different, the first composite target 205 of the previous process is used as the alignment reference of the laminated circuit of the subsequent process, so that higher alignment precision can be provided, the reference target hole 202 can be used as the alignment reference of the laminated drilling hole and the laminated buried hole, and is used as the initial alignment reference of the laminated blind hole, so that the alignment reference is switched after the corresponding metal target (such as the second metal target 204) is exposed, and higher alignment precision is realized. According to different lamination processing requirements, the processing can be performed according to at least one procedure of lamination drilling, lamination blind holes and lamination buried holes until the processing of all layers is completed.
Meanwhile, based on the composite target (the structure after the through hole is formed in the center of the first annular target 203) generated in the previous process as the alignment reference of the laminated circuit in the subsequent process, the spatial correlation of the annular distribution through hole and the central through hole is utilized to provide dual alignment references of radial distribution characteristics and central positioning characteristics, so that the positioning deviation of each laminated process only affects the current level, and the error is prevented from overlapping layer by layer to the subsequent process. In addition, through the synergistic effect of the reference target hole 202 and the composite target in the repeated processing process, the annular through hole of the composite target in the previous process provides a local compensation reference for the subsequent blind hole/buried hole processing, and the central through hole inherits the global positioning information of the reference target hole 202, so that the layer-by-layer convergence of alignment errors is realized in the multi-layer stack, and the processing alignment precision and the processing reliability of the HDI circuit board are improved.
In the above-mentioned inner layer circuit process, the inner core board 101 processes the first circuit layer and forms the process side with the first metal target 201 to obtain the first semi-finished product 102, which includes:
based on the alignment function and the pre-given expansion and contraction coefficients of the direct imaging device, the first circuit layer is processed on the inner core board 101 and a process side with the first metal target 201 is formed, so that a first semi-finished product 102 is obtained.
Illustratively, a direct imaging apparatus (DI apparatus DIRECT IMAGING MACHINE) is an exposure apparatus for direct imaging, which can directly form fine line patterns on the inner core board 101 by UV (ultraviolet) laser scanning, capture the positions of UV Mark points (optical calibration marks) preset by the inner core board 101 by a camera, adjust the positions of the exposure patterns in real time, and eliminate deformation or offset of the inner core board 101 itself. Compared with the traditional film exposure, the direct imaging equipment exposure does not need a physical mask, so that the problem of unstable film size is avoided, and the precise matching of UV Mark points after the graph scaling is ensured by giving the expansion and contraction coefficients in advance. The first metal target 201 is synchronously processed at the process side in the process of manufacturing the circuit pattern, so that a continuous alignment control system can be formed, and the precise interlayer alignment of the multi-layer HDI board can be realized through the cooperation of precompensation material expansion and contraction, high-precision alignment of DI equipment and a target transmission system. The preshaped expansion coefficient compensates the compression deformation, the DI equipment ensures the instant precision of the graphic imaging, and the target of the process side provides a stable physical positioning reference for the subsequent process, thereby realizing the closed-loop control of alignment.
In the lamination drilling target process, a reference target hole 202 is processed at the process side of lamination of the semi-finished product based on the first metal target 201, to obtain a second semi-finished product 103, including:
performing alignment recognition on the first metal target 201 based on an X-Ray alignment function of the laminated drilling target equipment;
The reference target hole 202 is processed at the process side of laminating the semi-finished product based on the first metal target 201, resulting in the second semi-finished product 103.
For example, the lamination drilling process may employ a lamination X-Ray drilling integrated apparatus as a lamination drilling apparatus, and the first metal target 201 may be aligned and identified by penetrating a resin layer of the laminate material using an X-Ray (X-Ray) alignment function of the apparatus. In the earlier stage inner layer circuit process, geometric correction is carried out on the circuit layer through pre-giving the expansion coefficient, so that pose deviation of the first metal target 201 caused by material thermodynamic deformation can be effectively restrained, the first metal target 201 is used as an alignment reference for manufacturing the reference target hole 202, and the alignment precision of the multi-level interconnection structure can be improved. Wherein the two opposite sides of the laminated semi-finished product are provided with process edges, a plurality of reference target holes 202, for example 4, can be processed on the process edges, and the plurality of reference target holes 202 are distributed at different positions, namely, the plurality of reference target holes 202 are processed on the two opposite process edges of the laminated semi-finished product based on the first metal target 201, so as to obtain the second semi-finished product 103. It should be appreciated that the number of alignment marks such as targets, target holes, etc. in this embodiment may be plural, and the arrangement position is determined according to the actual design requirement.
In the lamination drilling process, the second semi-finished product 103 is drilled based on the reference target hole 202, and the first annular target 203 with the circumferentially distributed through holes is processed at the process side, so as to obtain a third semi-finished product 104, which comprises:
the second semi-finished product 103 is drilled based on the reference target hole 202, and a first annular target 203 is processed at the process side by adopting the minimum aperture to obtain a third semi-finished product 104, wherein the first annular target 203 comprises a central through hole 213 and a plurality of through holes distributed circumferentially around the central through hole 213.
For example, referring to fig. 4, the through holes of the first annular target 203 are machined by using the minimum aperture, the first annular target 203 includes a central through hole 213 and a plurality of through holes distributed around the central through hole 213 in a circumferential array, the aperture of each through hole is the minimum aperture in the board, the through hole with the minimum aperture is used as the alignment reference, the alignment error of the conventional target hole due to the precision can be greatly reduced, and the alignment precision can be further improved by the plurality of through holes distributed in the circumferential array. For example, the aperture of each of the through holes constituting the first annular targets 203 is 0.2mm, the number of through holes distributed around the central through hole 213 is 16, that is, in the lamination drilling process, the second semi-finished product 103 is drilled based on the reference target holes 202, and the first annular targets 203 having circumferentially distributed through holes are processed at the process side to obtain the third semi-finished product 104, comprising:
the second semi-finished product 103 is drilled based on the reference target hole 202, and the first annular target 203 is processed on the process side based on the aperture of 0.2mm to obtain the third semi-finished product 104, wherein the first annular target 203 comprises a central through hole 213 and 16 through holes distributed circumferentially around the central through hole 213.
In the lamination buried hole process, the sixth semi-finished product 107 is drilled based on the reference target hole 202 and penetrates through the center of the first annular target 203 to form a first composite target 205, resulting in a seventh semi-finished product 108, comprising:
The sixth semi-finished product 107 is drilled based on the reference target hole 202 and penetrates through the central through hole 213 of the first annular target 203 to form a first composite target 205, resulting in a seventh semi-finished product 108.
For example, referring to fig. 5 and 6, with the reference target hole 202 as an alignment reference, during drilling, the through holes 215 penetrating the central through hole 213 of the first annular target 203 are synchronously processed, so that the through holes 215 and a plurality of through holes circumferentially distributed in the first annular target form a first composite target 205, and the processing alignment precision and processing reliability of the HDI circuit board are improved by utilizing the characteristics of the first composite target 205.
Wherein drilling the sixth semi-finished product 107 based on the reference target hole 202 and penetrating the central through hole 213 of the first annular target 203 to form the first composite target 205, obtaining a seventh semi-finished product 108, includes:
And drilling the sixth semi-finished product 107 based on the reference target hole 202, and processing the central through hole 213 of the first annular target 203 into a through hole 215 to form a first composite target 205, thereby obtaining a seventh semi-finished product 108, wherein the aperture of the through hole 215 is larger than the central through hole 213 and smaller than the inner diameter of the first composite target 205.
Illustratively, by reasonably setting the aperture of the through-hole 215, the through-hole 215 may be made to penetrate the central through-hole 213 of the first annular target 203 while retaining the circumferentially distributed peripheral through-holes, thereby forming the first composite target 205.
In order to facilitate understanding of the inventive concept, a second-order eight-layer board is taken as an example and illustrated in fig. 2 to 9, wherein the stacked structure of the second-order eight-layer board is shown in fig. 9, and references L1 to L8 in fig. 9 refer to the first to eighth circuit layers. Because the L1 to L4 layers and the L8 to L5 layers are center-symmetrical, for convenience of description, key processes of the lamination process of the HDI circuit board will be described starting with the top view structure of the L1 to L4 layers of the inner core board 101. The left-hand side illustration of fig. 2 to 8 shows an illustration of the state of the semi-finished product before processing during the processing in the different processes, the right-hand side illustration shows an illustration of the state of the semi-finished product after processing, and the middle arrow indicates the processing change.
The embodiment also provides a processing alignment method of the HDI circuit board, which comprises the steps S201-S212. The steps of this embodiment are numbered for ease of examination and understanding, and the order of execution of the steps is not limited. Details of the respective steps are as follows:
s201, processing a first circuit layer on the inner core plate 101 and forming a process edge with a first metal target 201 to obtain a first semi-finished product 102;
For example, after the inner core board 101 is used as a core board of an eight-layer HDI circuit board, as shown in the left side of fig. 2, and a circuit pattern is processed, functional circuits and a first metal target 201 are formed on a copper foil on the surface of the inner core board 101, as shown in the right side of fig. 2, and the first circuit layer is an L4 layer of the HDI circuit board.
S202, processing a reference target hole 202 on the basis of a first metal target 201 while laminating a semi-finished product to obtain a second semi-finished product 103;
For example, referring to fig. 3, after finishing the circuit processing, laminating and pressing are performed, and laminated materials are stacked on the upper and lower sides of the first semi-finished product 102, where the functional circuit of the first semi-finished product 102 and the first metal target 201 are covered by the laminated materials, and the covered is indicated by a dotted line in fig. 3. The surface of the second semi-finished product 103 obtained by pressing and drilling is the copper foil for processing the L3 layer. A reference target hole 202 is machined in the second semi-finished product 103, as shown on the right side of fig. 3, the reference target hole 202 providing a registration reference for the subsequent process.
S203, drilling the second semi-finished product 103 based on the reference target hole 202, and processing a first annular target 203 with circumferentially distributed through holes at the process side to obtain a third semi-finished product 104;
illustratively, the drilling process is performed on the L3 layer, as shown in the left mark A2 of fig. 4, and the first annular targets 203 are processed synchronously, where the first annular targets 203 include a central through hole 213 and 16 peripheral through holes distributed around the circumference of the central through hole 213, and the apertures of the central through hole 213 and the peripheral through holes are the smallest aperture of the L3 layer.
S204, processing a second circuit layer and a second metal target 204 on the third semi-finished product 104 based on the first annular target 203 to obtain a fourth semi-finished product 105;
Illustratively, after drilling is completed, a second circuit layer, such as a circuit indicated by a symbol A3 in fig. 4, and a second metal target 204 are processed on the copper foil on the surface of the third semi-finished product 104, using the first annular target 203 as a positioning reference, to obtain a fourth semi-finished product 105.
S205, re-drilling a reference target hole 202 after laminating the fourth semi-finished product 105 to obtain a fifth semi-finished product 106;
Illustratively, the laminate is stacked and laminated on opposite sides of the fourth semi-finished product 105, and the circuit patterns and vias on opposite sides of the fourth semi-finished product 105 are covered with the laminate, which is shown in phantom in the left side of fig. 5. The reference target hole 202 is electroplated with metal after the processing of the step S204 to form a metallized through hole, and the repositioning can be performed in the same manner as the step S202, that is, the laminated material needs to be pre-windowed by etching copper foil before lamination.
S206, laser windowing is performed on the fifth semi-finished product 106 based on the reference target hole 202 to expose a second metal target 204 and a first annular target 203, and blind holes are processed by the second metal target 204, so that a sixth semi-finished product 107 is obtained;
for example, after lamination and lamination, the surface of the semi-finished product is copper foil for forming an L2 layer, and the laser windowing is performed on the fifth semi-finished product 106 by using the reference target hole 202 to expose the covered second metal target 204 and the first annular target 203, then the alignment reference is switched, and the second metal target 204 is used as the alignment reference to process the blind hole, as shown in a mark A4 on the right side of fig. 5.
S207, drilling the sixth semi-finished product 107 based on the reference target hole 202 and penetrating through the center of the first annular target 203 to form a first composite target 205, so as to obtain a seventh semi-finished product 108;
Illustratively, with the reference target hole 202 as a registration reference, a drilling process is performed on the sixth semi-finished product 107, as shown by a sign A5 on the left side of fig. 6, and a through-hole 215 is processed in the center of the first annular target 203, the through-hole 215 having a hole diameter larger than the center through-hole 213 and smaller than the inner diameter of the first annular target 203 (the diameter of an inscribed circle formed by the peripheral through-holes), so that the through-hole 215 covers the center through-hole 213, so that the through-hole 215 and the first annular target 203 form a first composite target 205.
S208, processing the third circuit layer and the third metal target 206 on the seventh semi-finished product 108 based on the first composite target 205 to obtain an eighth semi-finished product 109;
Illustratively, the surface copper foil of the seventh semi-finished product 108 is processed into a third circuit layer and a third metal target 206 is formed with the first composite target 205 as a registration reference, and the circuit in the third circuit layer is shown as a mark A6 on the right side of fig. 6.
S209, re-drilling a reference target hole 202 after laminating the eighth semi-finished product 109 to obtain a ninth semi-finished product 110;
Illustratively, after the processing of the third wiring layer is completed, lamination and lamination are performed again, and the wiring of the third wiring layer, the third metal target 206, and the like are covered with the lamination material, the left side of fig. 7 being covered with a broken line. And forming the copper foil for processing the L1 circuit layer (outer layer) on the surface of the semi-finished product subjected to lamination. The fiducial target hole 202 is re-drilled to provide alignment fiducials for subsequent processing.
S210, windowing the ninth semi-finished product 110 based on the reference target hole 202 to expose a third metal target 206, processing a blind hole by the third metal target 206, and processing a second annular target 207 containing circumferentially distributed through holes at the process side to obtain a tenth semi-finished product 111;
Illustratively, as shown on the right side of fig. 7, the ninth semi-finished product 110 is laser windowed with the reference target hole 202 as a registration reference to expose the third metal target 206, then a blind hole is processed with the third metal target 206, as shown on the right side of fig. 7 by a mark A7, and a second annular target 207 is processed on the process side, and the structure of the second annular target 207 is the same as that of the first annular target 203.
S211, drilling the tenth semi-finished product 111 based on the reference target hole 202 and penetrating through the center of the second annular target 207 to form a second composite target 208, so as to obtain an eleventh semi-finished product 112;
Illustratively, the tenth semi-finished product 111 is drilled with the reference target hole 202 as an alignment reference, as shown by reference A8 in fig. 8, through the center of the second annular target 207 during the drilling process to form a second composite target 208 for use as an alignment reference for a subsequent process.
S212, processing the fourth line layer on the eleventh semi-finished product 112 based on the second composite target 208.
Illustratively, the copper foil on the surface of the eleventh semi-finished product 112 is processed into a fourth circuit layer, i.e., an L1 layer, with the second composite target 208 as a positioning reference, and the processed circuit is shown as a mark A9 on the right side of fig. 8, so that the processing of the outer layer circuit can be completed.
Meanwhile, based on the composite target (the structure after the through hole is formed in the center of the first annular target 203) generated in the previous process as the alignment reference of the laminated circuit in the subsequent process, the spatial correlation of the annular distribution through hole and the central through hole is utilized to provide dual alignment references of radial distribution characteristics and central positioning characteristics, so that the positioning deviation of each laminated process only affects the current level, and the error is prevented from overlapping layer by layer to the subsequent process. In addition, through the synergistic effect of the reference target hole 202 and the composite target in the repeated processing process, the annular through hole of the composite target in the previous process provides a local compensation reference for the subsequent blind hole/buried hole processing, and the central through hole inherits the global positioning information of the reference target hole 202, so that the layer-by-layer convergence of alignment errors is realized in the multi-layer stack, and the processing alignment precision and the processing reliability of the HDI circuit board are improved.
The embodiment also provides an HDI circuit board, which is prepared by the processing alignment method of the HDI circuit board. The processing alignment method and beneficial effects of the HDI circuit board can be specifically referred to above, and are not described herein.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of one of ordinary skill in the art without departing from the spirit of the present invention.