A PCB and method of z-direction interconnection thereof

Abstract

The application discloses a PCB and a Z-direction interconnection method thereof, which comprises the following steps: providing a first sub-board, a second sub-board and a bonding sheet for bonding the first sub-board and the second sub-board; forming first through holes in the Z-direction interconnection area of the first sub-board and the second sub-board; filling conductive paste with fluidity into each first through hole to form a plug hole after electroplating is completed on each first through hole; forming a plurality of vacuum extraction holes uniformly distributed around at least one plug hole; forming second through holes at the position where the bonding sheet and the vacuum extraction holes overlap; stacking the first sub-board, the bonding sheet and the second sub-board in sequence; performing vacuum extraction on each vacuum extraction hole during the pressing process of the first sub-board, the bonding sheet and the second sub-board, improving the vacuum degree of each vacuum extraction hole, and making the conductive paste in the first through hole fill into the second through hole; and solidifying the conductive paste in the plug hole after the pressing of the first sub-board and the second sub-board is completed, so that the product yield is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of PCB manufacturing technology, and more particularly to a PCB and its Z-axis interconnection method. Background Technology

[0002] Z-axis interconnect is a new technology for arbitrary interconnection between stacked core boards in PCBs, and electrical connections between sub-boards are usually achieved through conductive paste. Figure 1 This is a schematic diagram of an interlayer Z-axis interconnection process in a PCB in the prior art, such as... Figure 1 As shown, firstly, through-holes are fabricated and electroplated on two sub-boards (sub-board 01 and sub-board 02) of the PCB. For through-holes requiring Z-axis interconnection, POFV (plate over filled via, i.e., resin-filled via electroplating) is then fabricated. Next, an adhesive film 03 and a PET film 04 are quickly laminated onto one of the sub-boards. The adhesive film 03 and PET film 04 covering the POFV through-holes are then laser-ablated to create blind vias 05. Conductive paste 06 is then screen-printed into the blind vias, and the board is baked. Finally, the PET film 04 is removed, and the two sub-boards are pressed together. The two sub-boards are bonded together using the adhesive film 03, thus forming a Z-axis interconnection structure between the two sub-boards. This technology can be used to solve the problem of fabricating through-holes with high aspect ratios.

[0003] The Z-axis interconnection method described above has the following main drawbacks:

[0004] (1) Since conductive paste needs to be inserted into the blind hole of the adhesive sheet on one of the sub-boards in advance, the PET film on the adhesive sheet and the adhesive sheet need to maintain a low bonding force (excessive bonding force is not conducive to subsequent film removal and is easy to bring up the incompletely cured resin). Figure 2 This is a schematic diagram of another interlayer Z-axis interconnection process in existing PCB technology, such as... Figure 2 As shown, repeated scraping of the PET film by the squeegee during the screen printing process can easily cause the PET film and the adhesive sheet to separate. It can also cause the conductive paste to be scraped to areas outside the blind holes. When the two sub-boards are pressed together, it will cause a large-area short circuit.

[0005] (2) After the adhesive sheet is pressed onto the sub-board, it is exposed to the air for a long time, which can easily cause contamination and introduce surface debris, thus hindering the bonding and pressing between the two subsequent sub-boards. Summary of the Invention

[0006] This invention provides a PCB and its Z-axis interconnection method to achieve interlayer Z-axis conductive interconnection of a PCB with simple process and low cost.

[0007] According to one aspect of the present invention, a Z-axis interconnection method for a PCB is provided, comprising:

[0008] Provides a first sub-board, a second sub-board requiring Z-axis interconnection, and an adhesive sheet for bonding the first sub-board and the second sub-board;

[0009] A first through-hole is formed in the Z-direction interconnection region of the first sub-board and the second sub-board;

[0010] After electroplating each of the first through holes, a fluid conductive paste is filled into each of the first through holes to form a plug hole;

[0011] A plurality of uniformly distributed vacuum holes are formed around at least one of the plug holes;

[0012] A second through hole is formed at the position where the adhesive sheet overlaps with the vacuum hole;

[0013] Stack the first sub-board, the adhesive sheet, and the second sub-board in sequence;

[0014] During the pressing process of the first sub-board, the adhesive sheet and the second sub-board, the vacuum holes are evacuated to increase the vacuum level of each vacuum hole, so that the conductive paste in the first through hole can be filled into the second through hole.

[0015] After the first sub-board and the second sub-board are pressed together, the conductive paste in the plug hole is cured.

[0016] Optionally, after filling each of the through holes with a fluid conductive paste to form a plug, the method further includes:

[0017] Adhesive tape is applied to both ends of each of the plug holes to seal them.

[0018] Optionally, before sequentially stacking the first sub-plate, the adhesive sheet, and the second sub-plate, the method further includes:

[0019] Remove the tape from the side of the first sub-board closest to the second sub-board, and remove the tape from the side of the second sub-board closest to the first sub-board.

[0020] Optionally, after completing the lamination of the first sub-plate and the second sub-plate, the process further includes:

[0021] Remove the tape from the side of the first sub-board that is away from the second sub-board, and remove the tape from the side of the second sub-board that is away from the first sub-board.

[0022] Optionally, before stacking the first sub-plate, the adhesive sheet, and the second sub-plate in sequence, the method further includes:

[0023] The Z-axis interconnection region of the adhesive sheet is cut into a pattern.

[0024] Optionally, the graphic is a cross shape.

[0025] Optionally, after completing the lamination of the first sub-plate and the second sub-plate, the process further includes:

[0026] The conductive paste in the plug hole is then replenished and filled.

[0027] Optionally, pressing the first sub-plate, the adhesive sheet, and the second sub-plate together includes:

[0028] A first laminated steel sheet is provided on the side of the first sub-plate opposite to the second sub-plate;

[0029] A window is made at the position where the first laminated steel plate overlaps with the vacuum hole;

[0030] A second laminated steel sheet is provided on the side of the second sub-plate opposite to the first sub-plate;

[0031] A window is made at the position where the second laminated steel plate overlaps with the vacuum hole;

[0032] Pressure is applied to the first laminated steel sheet and the second laminated steel sheet to press the first sub-plate, the adhesive sheet and the second sub-plate together.

[0033] Optionally, the pressing of the first sub-plate, the adhesive sheet, and the second sub-plate further includes:

[0034] A first buffer layer is provided between the first laminated steel plate and the first sub-plate;

[0035] A window is made at the location where the first buffer layer overlaps with the vacuum hole;

[0036] A second buffer layer is provided between the second laminated steel plate and the second subplate;

[0037] A window is made at the location where the second buffer layer overlaps with the vacuum hole.

[0038] According to another aspect of the present invention, a PCB is provided in which the Z-axis interconnection between sub-boards is completed using the above-described PCB Z-axis interconnection method.

[0039] The Z-axis interconnection method for PCBs provided in this invention involves forming a first through-hole in the Z-interconnection region of a first sub-board and a second sub-board requiring Z-axis interconnection. After electroplating the first through-hole, a flowable conductive paste is filled into it to form a plug. Then, a plurality of uniformly distributed vacuum holes are formed around the plug holes of at least one sub-board. Second through-holes are formed on the adhesive sheet between the first and second sub-boards at locations overlapping with the vacuum holes. During the pressing process of stacking the first sub-board, adhesive sheet, and second sub-board, a vacuuming operation is performed on each vacuum hole to allow the flowable conductive paste to penetrate. The adhesive sheet flows from the center to the surrounding second through holes and vacuum holes, creating a hollow center. This allows the conductive paste in the plug holes of the first and second sub-boards to flow towards the hollowed-out area due to pressure, forming a Z-axis connection structure. After pressing, the conductive paste is cured to form a Z-axis interconnect between the first and second sub-boards. This eliminates the need for the POFV process on the sub-board and the screen printing process for the conductive paste in existing technologies. It avoids the problem of conductive paste being screen-printed onto unwanted areas and prevents the adhesive layer from being exposed to air for extended periods, thus improving product yield and simplifying the process. Furthermore, it eliminates the need for protective film materials such as PET film, which helps reduce costs.

[0040] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of an interlayer Z-axis interconnection process in a PCB in the prior art;

[0043] Figure 2 This is a schematic diagram of another interlayer Z-axis interconnection process in PCBs in the prior art;

[0044] Figure 3 This is a flowchart of a Z-axis interconnection method for a PCB provided in an embodiment of the present invention;

[0045] Figure 4 This is a process diagram of a Z-axis interconnection method for a PCB provided in an embodiment of the present invention;

[0046] Figure 5 This is a flowchart of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention;

[0047] Figure 6 This is a process diagram of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention;

[0048] Figure 7 This is a schematic diagram of the structure of an adhesive sheet provided in an embodiment of the present invention;

[0049] Figure 8 This is a flowchart of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention;

[0050] Figure 9 This is a process diagram of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention. Detailed Implementation

[0051] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0052] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0053] Figure 3 This is a flowchart of a Z-axis interconnection method for a PCB provided in an embodiment of the present invention, as shown below. Figure 3 As shown, it includes:

[0054] S110, providing a first daughterboard, a second daughterboard requiring Z-axis interconnection, and an adhesive sheet for bonding the first daughterboard and the second daughterboard.

[0055] Specifically, the first and second sub-boards can be single-layer core boards with completed circuit fabrication, or multi-layer core boards formed by laminating multiple core boards after circuit fabrication. The adhesive sheet can be a fluid colloid. When the first and second sub-boards need to be laminated, the adhesive sheet can be placed between the first and second sub-boards, allowing them to bond together and ensuring the PCB's stability.

[0056] S120, a first through-hole is formed in the Z-direction interconnection region of the first daughter board and the second daughter board.

[0057] Specifically, the Z-axis interconnect region can be understood as the region where stacked sub-boards are electrically connected through conductive structures. Figure 4 This is a process diagram of a Z-axis interconnection method for a PCB provided in an embodiment of the present invention, as shown below. Figure 4 As shown, a first through-hole 3 can be formed in the Z-direction interconnection region A of the first sub-board 1 and the second sub-board 2.

[0058] S130. After electroplating each first through hole, fill each first through hole with a fluid conductive paste to form a plug hole.

[0059] For details, please refer to Figure 4 After forming the first through hole 3 on the first daughter board 1 and the second daughter board 2, chemical copper plating and electroplating are usually performed on the hole wall of the first through hole 3 to form a conductive layer 4 on the hole wall of the first through hole 3. After forming the conductive layer 4, a fluid conductive paste 5 can be filled into the first through hole 3, so that the conductive paste fills the through hole and forms a plug hole 6.

[0060] S140. A plurality of uniformly distributed vacuum holes are formed around at least one plug hole.

[0061] For details, please refer to [link / reference]. Figure 4 The vacuum hole 7 can also be a through hole penetrating the sub-plate. Multiple vacuum holes 7 can be evenly distributed around the plug hole 6 of one of the sub-plates. For example, multiple vacuum holes 7 can be evenly distributed around the plug hole 6 of the first sub-plate 1, or around the plug hole 6 of the second sub-plate 2. Alternatively, multiple evenly distributed vacuum holes 7 can be formed around the plug holes 6 of both the first sub-plate 1 and the second sub-plate 2. Preferably, in this embodiment of the invention, four evenly distributed vacuum holes 7 are formed around the plug holes 6 of both the first sub-plate 1 and the second sub-plate 2. When multiple evenly distributed vacuum holes 7 are formed around the plug holes 6 of the two sub-plates, the number of vacuum holes 7 on the two sub-plates can be equal, and the vacuum holes 7 on the two sub-plates can overlap after stacking.

[0062] S150, A second through hole is formed at the position where the adhesive sheet and the vacuum hole overlap.

[0063] For details, please refer to [link / reference]. Figure 4 Since the first sub-plate 1 and the second sub-plate 2 need to be bonded together by the adhesive sheet 8, a second through hole 9 can be formed at the position where the adhesive sheet overlaps with the vacuum hole 7 before the first sub-plate 1 and the second sub-plate 2 are bonded and pressed together. Preferably, the size of the second through hole 9 coincides with the size of the overlapping vacuum hole 7.

[0064] S160. Stack the first sub-board, the adhesive sheet, and the second sub-board in sequence.

[0065] S170. During the pressing process of the first sub-board, the adhesive sheet and the second sub-board, vacuum is applied to each vacuum hole to increase the vacuum level of each vacuum hole, so that the conductive paste in the first through hole can be filled into the second through hole.

[0066] Specifically, PCB sub-board lamination equipment can be used to laminate the first sub-board 1, the bonding sheet 8, and the second sub-board 2. (Continue to refer to...) Figure 4 During the pressing process of the first sub-board 1, the adhesive sheet 8, and the second sub-board 2, pressure can be applied while simultaneously performing the same vacuuming operation on each vacuuming hole 7. Due to the pressure and the uniform distribution of the vacuuming holes 7 around the plugging hole 6, the stress on the adhesive sheet 8 is concentrated in the middle. The adhesive sheet 8, with its certain flow characteristics, will flow from the middle to the surrounding second through holes 9, resulting in a hollowed-out middle position on the adhesive sheet 8. Since the second through holes 9 overlap with the vacuuming holes 7 uniformly distributed around the plugging hole 6, the middle position of the adhesive sheet 8 overlaps with the plugging hole 6. Thus, after the middle position of the adhesive sheet 8 is hollowed out, the pressure generated by the vacuuming will cause the conductive paste 5 in the plugging holes 6 of the first sub-board 1 and the second sub-board 2 to flow towards the hollowed-out position of the adhesive sheet 8, thereby connecting the first sub-board 1 and the second sub-board 2 through the conductive paste 5 flowing to the plugging hole 6. The vacuuming operation is performed on each vacuum hole 7 during the pressing process, rather than after the pressing is completed. This avoids the lack of fluidity of the adhesive sheet after pressing, which makes it difficult to make it flow and form holes by vacuuming.

[0067] S180. After the first and second daughter boards are pressed together, the conductive paste in the plug holes is cured.

[0068] Specifically, after the first and second sub-boards are pressed together, the conductive paste can be cured by baking, and the adhesive sheet can be cured at the same time.

[0069] For example, because the conductive paste in the plug holes of the first and second sub-boards flows into the hollow spaces in the adhesive sheet due to vacuum pressure, the conductive paste in the plug holes of the first and second sub-boards will be recessed. Therefore, after the first and second sub-boards are laminated, conductive paste can be filled into the first through hole again to fill the hole completely, ensuring the conductivity after the two sub-boards are interconnected in the Z direction. The conductive paste in the plug holes can be replenished and leveled before curing, so that the conductive paste in the plug holes can be cured together after replenishment and leveling. Alternatively, the conductive paste in the unfilled plug holes can be cured first, and then the conductive paste in the plug holes can be filled, followed by another curing. This embodiment of the invention does not specifically limit this approach.

[0070] The Z-axis interconnection method for PCBs provided in this invention involves forming a first through-hole in the Z-interconnection region of a first sub-board and a second sub-board requiring Z-axis interconnection. After electroplating the first through-hole, a flowable conductive paste is filled into it to form a plug. Then, a plurality of uniformly distributed vacuum holes are formed around the plug holes of at least one sub-board. Second through-holes are formed on the adhesive sheet between the first and second sub-boards at locations overlapping with the vacuum holes. During the pressing process of stacking the first sub-board, adhesive sheet, and second sub-board, a vacuuming operation is performed on each vacuum hole to allow the flowable conductive paste to penetrate. The adhesive sheet flows from the center to the surrounding second through holes and vacuum holes, creating a hollow center. This allows the conductive paste in the plug holes of the first and second sub-boards to flow towards the hollowed-out area due to pressure, forming a Z-axis connection structure. After pressing, the conductive paste is cured to form a Z-axis interconnect between the first and second sub-boards. This eliminates the need for the POFV process on the sub-board and the screen printing process for the conductive paste in existing technologies. It avoids the problem of conductive paste being screen-printed onto unwanted areas and prevents the adhesive layer from being exposed to air for extended periods, thus improving product yield and simplifying the process. Furthermore, it eliminates the need for protective film materials such as PET film, which helps reduce costs.

[0071] Optional, Figure 5 This is a flowchart of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the Z-axis interconnection method of this PCB includes:

[0072] S211. Provides a first daughterboard, a second daughterboard that require Z-axis interconnection, and an adhesive sheet for bonding the first daughterboard and the second daughterboard.

[0073] S212, A first through-hole is formed in the Z-direction interconnection region of the first daughter board and the second daughter board.

[0074] S213. After electroplating each first through hole, fill each first through hole with a fluid conductive paste to form a plug.

[0075] S214. Apply tape to both ends of each plug hole to seal each plug hole.

[0076] Specifically, Figure 6 This is a process diagram of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention, as shown below. Figure 6 As shown, conductive paste 5 is filled into the through holes 3 of the first sub-board 1 and the second sub-board 2 to form plug holes 6. After that, the two ends of the plug holes 6 can be sealed with tape 10 to prevent the conductive paste 5 from flowing out.

[0077] S215. A plurality of uniformly distributed vacuum holes are formed around at least one plug hole.

[0078] S216. A second through hole is formed at the position where the adhesive sheet overlaps with the vacuum hole.

[0079] S217. Cut the pattern in the Z-axis interconnection area of ​​the adhesive sheet.

[0080] Specifically, Figure 7 This is a schematic diagram of the structure of an adhesive sheet provided in an embodiment of the present invention, in conjunction with reference to the reference. Figure 6 and Figure 7 Pattern 11 can be cut into the Z-axis interconnection area of ​​the adhesive sheet 8 using laser cutting, that is, at the position where the adhesive sheet 8 overlaps with the plug hole 6. In this way, during the pressing process of the first sub-board 1, the adhesive sheet 8, and the second sub-board 2, when the vacuuming operation is performed on each vacuum hole 7, the adhesive sheet 8 at the position where pattern 11 is cut is easy to crack and flow into the surrounding second through holes 9. A small vacuum pressure is required to create a hollow at the position where the adhesive sheet 8 overlaps with the plug hole 6. The cut pattern 11 can penetrate through the adhesive layer 8.

[0081] For example, the cut pattern 11 can be set according to design requirements, as long as it can achieve the effect of forming a hollow in the accurate position in the embodiment of the present invention. The embodiment of the present invention does not make specific limitations in this regard. For example, the pattern 11 can be a "+" shape or a circle.

[0082] S218. Remove the tape from the side of the first sub-board closest to the second sub-board, and remove the tape from the side of the second sub-board closest to the first sub-board.

[0083] Specifically, in order to facilitate the connection of conductive paste in the plug holes of the first sub-board 1 and the second sub-board 2 during the pressing process, the tape 10 on the side of the first sub-board 1 closest to the second sub-board 2 can be removed, and the tape 10 on the side of the second sub-board 2 closest to the first sub-board 1 can also be removed.

[0084] S219. Stack the first sub-board, the adhesive sheet, and the second sub-board in sequence.

[0085] S220. During the pressing process of the first sub-board, the adhesive sheet and the second sub-board, vacuum is applied to each vacuum hole to increase the vacuum level of each vacuum hole, so that the conductive paste in the first through hole can be filled into the second through hole.

[0086] Specifically, the greater the vacuum level of each vacuum hole 7, the greater the vacuum pressure exerted on the adhesive sheet 8 in the Z-direction interconnection region A, resulting in a larger perforation at that location. Experiments can be conducted to determine the relationship between the vacuum level of each vacuum hole 7, the pressure, temperature, and time of pressing the two sub-boards together, and the perforation size. This ensures that the vacuum pressure applied to the adhesive sheet 8 results in a suitable perforation size in the Z-direction interconnection region A. This prevents issues such as excessively large perforations leading to conductive paste overflow and short circuits, and insufficient conductive paste connection between the two sub-boards due to insufficient perforations, resulting in poor conductivity. The goal is to ensure that the perforation size of the adhesive sheet 8 is just right to allow for the connection of the conductive paste between the two sub-boards, thus guaranteeing good conductive connectivity between them.

[0087] S221. After the first and second sub-boards are pressed together, the conductive paste in the plug holes is replenished and filled.

[0088] Specifically, you can first remove the tape on the side of the first sub-board 1 that is away from the second sub-board 2, and then fill the conductive paste 5 in the plug hole 6 of the first sub-board 1 with the paste. Similarly, you can remove the tape on the side of the second sub-board 2 that is away from the first sub-board 1, and then fill the conductive paste 5 in the plug hole 6 of the second sub-board 2 with the paste.

[0089] S222. Curing the conductive paste in the plug hole.

[0090] Optional, Figure 8 This is a flowchart of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention, as shown below. Figure 8 As shown, the Z-axis interconnection method of this PCB includes:

[0091] S311, providing a first daughterboard, a second daughterboard requiring Z-axis interconnection, and an adhesive sheet for bonding the first daughterboard and the second daughterboard.

[0092] S312, A first through-hole is formed in the Z-direction interconnection region of the first daughter board and the second daughter board.

[0093] S313. After electroplating each first through hole, fill each first through hole with a fluid conductive paste to form a plug hole.

[0094] S314. Apply tape to both ends of each plug hole to seal each plug hole.

[0095] S315. A plurality of uniformly distributed vacuum holes are formed around at least one plug hole.

[0096] S316. A second through hole is formed at the position where the adhesive sheet and the vacuum hole overlap.

[0097] S317. Cut the pattern in the Z-axis interconnection area of ​​the adhesive sheet.

[0098] S318. Remove the tape from the side of the first sub-board closest to the second sub-board, and remove the tape from the side of the second sub-board closest to the first sub-board.

[0099] S319. Stack the first sub-board, the adhesive sheet, and the second sub-board in sequence.

[0100] S320, A first laminated steel sheet is provided on the side of the first subplate opposite to the second subplate.

[0101] S321. Make a window at the position where the first layer of steel plate overlaps with the vacuum hole.

[0102] S322, A second laminated steel sheet is provided on the side of the second subplate opposite to the first subplate.

[0103] S323. Make a window at the position where the second layer of steel plate overlaps with the vacuum hole.

[0104] S324. Apply pressure to the first and second lamination plates to press the first subplate, adhesive sheet, and second subplate together.

[0105] Specifically, Figure 9 This is a process diagram of another Z-axis interconnection method for PCBs provided in an embodiment of the present invention, as shown below. Figure 9 As shown, after the first sub-board 1, adhesive sheet 8, and second sub-board 2 are stacked sequentially, a first laminating steel plate 12 and a second laminating steel plate 13 can be respectively placed on the outward side of the stacked first core board 1 and second core board 2. Thus, when pressing the first sub-board 1, adhesive sheet 8, and second sub-board 2, relative pressure can be applied to the outward first laminating steel plate 12 and second laminating steel plate 13, thereby achieving pressing of the first sub-board 1, adhesive sheet 8, and second sub-board 2 and providing protection for the first sub-board 1 and second sub-board 2. Furthermore, a window can be made at the position where the first laminating steel plate 12 and second laminating steel plate 13 overlaps with the vacuum hole 7, forming a through hole. Preferably, the size of the window coincides with the vacuum hole, thus ensuring that the vacuum hole 7 can be evacuated during the lamination process. The first laminating steel plate 12 and second laminating steel plate 13 can be devices in a lamination equipment for laminating PCBs.

[0106] For example, pressing the first sub-plate 1, the adhesive sheet 8, and the second sub-plate 2 together further includes: providing a first buffer layer 14 between the first laminated steel plate 12 and the first sub-plate 1; making a window at the position where the first buffer layer 14 overlaps with the vacuum hole 7; providing a second buffer layer 15 between the second laminated steel plate 13 and the second sub-plate; and making a window at the position where the second buffer layer 15 overlaps with the vacuum hole 7.

[0107] For details, please refer to Figure 9 A first buffer layer 14 can be provided between the first laminated steel plate 12 and the first sub-plate 1, and a second buffer layer 15 can be provided between the second laminated steel plate 13 and the second sub-plate 2. This prevents the harder first laminated steel plate 12 from directly contacting the first sub-plate 1, and the harder second laminated steel plate 13 from directly contacting the second sub-plate 2. When pressure is applied to the first laminated steel plate 12 and the second laminated steel plate 13 to press the first sub-plate 1 and the second sub-plate 2 together, the buffering effect of the first buffer layer 14 and the second buffer layer 15 protects the first sub-plate 1 and the second sub-plate 2. Similarly, windows can be made at the intersection of the first buffer layer 14 and the vacuum hole 7, and windows can also be made at the intersection of the second buffer layer 15 and the vacuum hole 7. Preferably, the size of the windows in the first buffer layer 14 and the second buffer layer 15 coincides with the vacuum hole 7 to ensure subsequent vacuuming operations on the vacuum hole 7.

[0108] S325. During the pressing process of the first sub-board, the adhesive sheet and the second sub-board, vacuum is applied to each vacuum hole to increase the vacuum level of each vacuum hole, so that the conductive paste in the first through hole can be filled into the second through hole.

[0109] S326. After the first and second daughter boards are pressed together, the conductive paste in the plug holes is replenished and leveled.

[0110] Specifically, at this time, the first layer of steel plate 12 and the second layer of steel plate 13 can be removed first. If the first buffer layer 14 and the second buffer layer 15 are included, the first buffer layer 14 and the second buffer layer 15 also need to be removed. Then, the tape on the side of the first sub-board 1 away from the second sub-board 2 is torn off, and the tape on the side of the second sub-board 2 away from the first sub-board 1 is torn off. Then, the conductive paste 5 in the plug hole 6 in the first sub-board 1 is to be filled and leveled, and the conductive paste 5 in the plug hole 6 in the second sub-board 2 is to be filled and leveled.

[0111] S327. Curing the conductive paste in the plug hole.

[0112] Based on the same inventive concept, this embodiment of the invention also provides a PCB, which uses the Z-axis interconnection method of the PCB provided in any embodiment of the invention to complete the Z-axis interconnection between sub-boards. Therefore, the PCB provided in this embodiment of the invention includes the technical features of the Z-axis interconnection method of the PCB provided in any embodiment of the invention, and can achieve the beneficial effects of the Z-axis interconnection method of the PCB provided in any embodiment of the invention. The similarities can be referred to the above description of the Z-axis interconnection method of the PCB provided in this embodiment of the invention, and will not be repeated here.

[0113] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0114] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A Z-axis interconnection method for a PCB, characterized in that, include: Provides a first sub-board, a second sub-board requiring Z-axis interconnection, and an adhesive sheet for bonding the first sub-board and the second sub-board; A first through-hole is formed in the Z-direction interconnection region of the first sub-board and the second sub-board; After electroplating each of the first through holes, a fluid conductive paste is filled into each of the first through holes to form a plug hole; A plurality of uniformly distributed vacuum holes are formed around at least one of the plug holes; A second through hole is formed at the position where the adhesive sheet overlaps with the vacuum hole; Stack the first sub-board, the adhesive sheet, and the second sub-board in sequence; During the pressing process of the first sub-board, the adhesive sheet and the second sub-board, the vacuum holes are evacuated to increase the vacuum level of each vacuum hole, so that the conductive paste in the first through hole can be filled into the second through hole. After the first sub-board and the second sub-board are pressed together, the conductive paste in the plug hole is cured.

2. The Z-axis interconnection method for PCBs according to claim 1, characterized in that, After filling each of the aforementioned through holes with a fluid conductive paste to form a plug, the method further includes: Adhesive tape is applied to both ends of each of the plug holes to seal them.

3. The Z-axis interconnection method for PCBs according to claim 2, characterized in that, Before the first sub-board, the adhesive sheet, and the second sub-board are stacked sequentially, the method further includes: Remove the tape from the side of the first sub-board closest to the second sub-board, and remove the tape from the side of the second sub-board closest to the first sub-board.

4. The Z-axis interconnection method for PCBs according to claim 3, characterized in that, After the first sub-plate and the second sub-plate are laminated, the process also includes: Remove the tape from the side of the first sub-board that is away from the second sub-board, and remove the tape from the side of the second sub-board that is away from the first sub-board.

5. The Z-axis interconnection method for PCBs according to claim 1, characterized in that, Before stacking the first sub-board, the adhesive sheet, and the second sub-board in sequence, the method further includes: The Z-axis interconnection region of the adhesive sheet is cut into a pattern.

6. The Z-axis interconnection method for PCBs according to claim 5, characterized in that, The graphic is in the shape of a cross.

7. The Z-axis interconnection method for PCBs according to claim 1, characterized in that, After the first sub-plate and the second sub-plate are laminated, the process also includes: The conductive paste in the plug hole is then replenished and filled.

8. The Z-axis interconnection method for PCBs according to claim 1, characterized in that, The pressing of the first sub-plate, the adhesive sheet, and the second sub-plate includes: A first laminated steel sheet is provided on the side of the first sub-plate opposite to the second sub-plate; A window is made at the position where the first laminated steel plate overlaps with the vacuum hole; A second laminated steel sheet is provided on the side of the second sub-plate opposite to the first sub-plate; A window is made at the position where the second laminated steel plate overlaps with the vacuum hole; Pressure is applied to the first laminated steel sheet and the second laminated steel sheet to press the first sub-plate, the adhesive sheet and the second sub-plate together.

9. The Z-axis interconnection method for PCBs according to claim 8, characterized in that, The pressing of the first sub-plate, the adhesive sheet, and the second sub-plate further includes: A first buffer layer is provided between the first laminated steel plate and the first sub-plate; A window is made at the location where the first buffer layer overlaps with the vacuum hole; A second buffer layer is provided between the second laminated steel plate and the second subplate; A window is made at the location where the second buffer layer overlaps with the vacuum hole.

10. A PCB, characterized in that, The Z-axis interconnection method of the PCB according to any one of claims 1 to 9 is used to complete the Z-axis interconnection between sub-boards.

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