Novel manufacturing method of embedded copper block

Abstract

The invention relates to the technical field of PCBs (Printed Circuit Board), and discloses a novel manufacturing method of an embedded copper block, which comprises the following steps: S1, preparing materials; s2, lamination and groove milling treatment; s3, pre-burying a copper block; s4, performing vacuum resin hole plugging for the first time; s5, performing vacuum resin hole plugging for the second time; and S6, plate grinding treatment. The method is not influenced by the stacking structure, and the copper-embedded block can also be manufactured by using the stacking structure laminated by the copper foil; according to the technology for manufacturing the embedded copper block through the vacuum plug hole, only one-time shape milling is needed, the cost of the vacuum plug hole is slightly lower than that of the embedded copper block manufactured through lamination, the price of the embedded copper block manufactured through lamination is related to the number of used core plates and the number of PP, and along with increasing of layers, the price advantage of the embedded copper block manufactured through the vacuum plug hole is larger; the convex groove design is added in the milling groove design, so that the requirement of partial embedded copper blocks on the alignment degree can be met; when the embedded copper block is manufactured through vacuum resin hole plugging, the copper block is fixed through the adhesive tape, the copper block deviation problem is avoided, and the finished product qualification rate can be improved to a certain degree.

Description

Technical Field

[0001] The invention relates to the technical field of PCB, and in particular to a new method for manufacturing an embedded copper block. Background Art

[0002] When circuit boards are used in actual applications, it is inevitable that part of the electrical energy will be converted into internal energy. Some components have a higher conversion ratio and generate more heat, so it is necessary to consider corresponding heat dissipation measures to avoid affecting the life of the circuit boards.

[0003] The buried copper block heat dissipation technology occupies a very important position in today's heat dissipation methods. The copper block is buried in the circuit board under the components that generate more heat. The lower specific heat capacity of the copper block can quickly conduct heat and solve the heat dissipation problem.

[0004] Nowadays, the production method of buried copper block boards is usually lamination, that is, grooves are milled at the corresponding positions of the core board and the prepreg before lamination. During lamination, the copper blocks are placed in the milled grooves and fixed in the board by the flow of glue of the prepreg. This is also the main method for making buried copper blocks.

[0005] As more and more demands for buried copper blocks are put forward, the limitations of this method are gradually revealed. It can only support core+core lamination. When encountering Anylayer or HDI stacking structure that partially uses copper foil lamination, buried copper blocks cannot be made due to problems such as the inability to open windows and align the copper foil.

[0006] Therefore, we need to propose a new method for making buried copper blocks, which is not affected by the stacking structure and can also be made using a stacking structure of pressed copper foils, while saving costs. Summary of the invention

[0007] The purpose of the present invention is to provide a new method for making buried copper blocks, which is not affected by the stacking structure, and can also be made using a stacking structure pressed with copper foil; the process of making buried copper blocks by vacuum plugging only requires one milling of the outer shape, and the cost of vacuum plugging will be slightly lower than that of laminating buried copper blocks, and the price of laminating buried copper blocks is related to the number of core boards and PPs used. As the number of layers increases, the price advantage of buried copper blocks made by vacuum plugging will be relatively greater; a convex groove design is added to the milling groove design, so that the copper block is relatively more centered, which can solve the requirements of some buried copper blocks for alignment; when making buried copper blocks by vacuum resin plugging, the copper block is first fixed with tape, which avoids the problem of copper block deviation, and can improve the qualified rate of finished products to a certain extent, so as to solve the problems raised in the above-mentioned background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a new method for making an embedded copper block, comprising the following steps:

[0009] S1. Preparation of materials: Prepare the materials for embedding copper blocks on the circuit board, including copper blocks, PCB boards, high-temperature resistant tapes, vacuum resins, board grinding tools, and curing equipment.

[0010] S2. Laminating and milling groove treatment: Conduct laminating treatment and post-laminating treatment on the PCB board to make the board surfaces flat without bubbles and impurities, and use a milling machine to mill grooves for embedding copper blocks on the PCB board. The size of the milled grooves is larger than that of the copper blocks.

[0011] S3. Embedding copper blocks: Clean the groove surfaces of the milled grooves, and paste a high-temperature resistant tape on one side of the milled groove. The high-temperature resistant tape fits tightly against the edge of the milled groove, and then place the copper block into the milled groove to make the copper block adhere to the high-temperature tape, achieving the positioning of the copper block.

[0012] S4. First vacuum resin plugging of holes: Use a vacuum resin hole plugging device to inject the resin into the milled groove from the side where the high-temperature resistant tape is not pasted, and conduct curing treatment on the resin. Then remove the high-temperature resistant tape on one side of the milled groove.

[0013] S5. Second vacuum resin plugging of holes: Use a vacuum resin hole plugging device to inject the resin into the milled groove from the other side of the milled groove, and conduct curing treatment on the resin to make the resin tightly wrap the copper block.

[0014] S6. Board grinding treatment: Use a board grinding device to grind the PCB board to remove the residual resin that exceeds the surface of the PCB board during the vacuum resin hole plugging process, completing the production of the embedded copper block.

[0015] Preferably, in step S1, the high-temperature resistant tape is selected as a polyester film tape, the surface of the PCB board is flat, without scratch and bubble defects, the board grinding tool is selected as a ceramic brush, and the curing equipment is selected as an oven.

[0016] Preferably, in step S2, during laminating, stack copper foils, prepregs, PCB board substrates, prepregs, and copper foils in sequence from bottom to top, and then use a laminator to conduct laminating treatment and remove the excess edge materials.

[0017] During milling of the grooves, place the laminated PCB board on the workbench of the milling machine, and use a fixture to clamp and position it. Then start the milling machine and process the milled grooves by moving the milling cutter.

[0018] Preferably, in step S2, since the size of the milled grooves is larger than that of the copper blocks, in order to ensure that the copper blocks are centered when placed in the milled grooves and prevent the copper blocks from tilting and contacting the inner walls of the milled grooves, convex grooves are provided on the inner walls around the milled grooves, and two convex grooves are provided on each inner wall surface of the milled grooves. The convex grooves are cylindrical convex grooves with a radius of 5 mil.

[0019] Preferably, in step S3, for cleaning the grooved surface of the milling groove, a grinding machine is used to grind the grooved surface of the milling groove to remove burrs and uneven parts on the grooved surface;

[0020] When pasting the high-temperature resistant tape, the width and length of the high-temperature resistant tape are both larger than the size of the milling groove opening, and the high-temperature resistant tape is in full contact with the grooved surface of the milling groove to ensure that the high-temperature resistant tape is flat, without wrinkles and offsets.

[0021] Preferably, in step S3, the distance between the protruding grooves at opposite positions on the inner wall of the milling groove is 2 mil larger than the size of the copper block. When the copper block is placed in the milling groove, the protruding grooves play a limiting role on the copper block, making the copper block located at a position close to the center inside the milling groove and preventing the situation that the resin cannot be injected into the milling groove due to the contact between the copper block and the inner wall of the milling groove.

[0022] Preferably, in step S4, during the first vacuum resin plugging of the holes, it is made until oil oozes out at the position of the milling groove, and then the PCB board filled with resin is placed in an oven, and the baking board parameters are set as 80°C * 30 min + 110°C * 30 min + 150°C * 50 min for three-stage baking board curing treatment.

[0023] Preferably, in step S5, after tearing off the high-temperature resistant glue, a ceramic grinding plate is made. After the ceramic grinding plate is completed, vacuum resin plugging of the holes is carried out again from the front and back sides of the PCB board respectively, so that the injected resin is in full contact with the cured resin, that is, the resin fills the gap between the milling groove and the copper block;

[0024] Then the PCB board is placed in an oven, and the baking temperature of the board is set at 150°C, and the curing time is set at 0.5 h.

[0025] Preferably, in step S6, the PCB board filled with resin is placed on the workbench of the grinding plate equipment, the surface of the PCB board is made flat and without deformation, and the PCB board is fixed using a fixture. The grinding plate equipment is started, the ceramic grinding plate is driven to move, and the transmission speed of the ceramic grinding plate is controlled to remove the excess resin on the surface of the PCB board.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. The present invention is not affected by the stack structure, and buried copper blocks can also be made using the stack structure of copper foil lamination; the process of making buried copper blocks by vacuum plugging of holes only requires one milling of the outer shape once, and the cost of vacuum plugging of holes is also slightly lower than that of making buried copper blocks by lamination. Moreover, the price of making buried copper blocks by lamination is related to the number of core boards and PP. As the number of layers increases, the relative price advantage of making buried copper blocks by vacuum plugging of holes will be greater;

[0028] 2. In the milling groove design of the present invention, a convex groove design is added, making the copper block relatively more centered, which can meet the alignment requirements of some buried copper blocks; when making the buried copper block by vacuum resin plugging holes, since the copper block is fixed with tape first, the problem of copper block deviation is avoided, and the qualified rate of the finished product can be improved to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flowchart of the present invention;

[0030] Figure 2 is a schematic structural diagram of the milling groove and the convex groove of the present invention;

[0031] Figure 3 is a flowchart of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] Please refer to Figures 1-3 , the present invention provides a technical solution: a method for manufacturing a new embedded copper block, including the following steps:

[0034] S1. Prepare materials: Prepare the materials for embedding copper blocks on the circuit board, including copper blocks, PCB boards, high-temperature resistant tapes, vacuum resins, grinding tools, and curing equipment;

[0035] In step S1, the high-temperature resistant tape is selected as a polyester film tape to ensure that it will not fall off or deform during the resin curing process. The surface of the PCB board is flat, without scratches and bubble defects. The grinding tool is selected as a ceramic brush, and the curing equipment is selected as an oven. The surface of the copper block should be clean and free of oxidation. If necessary, polishing or pickling treatment can be carried out. According to the size, layout, and current requirements of the circuit board, determine the size and shape of the copper block. Preferably, to improve the heat dissipation capacity of the circuit board and the convenience of the copper block embedding method, the copper block is selected as a flat cuboid copper block.

[0036] S2. Laminating and milling groove treatment: Perform laminating treatment and post-laminating treatment on the PCB board to make the surfaces of the boards flat without bubbles and impurities, and use a milling machine to mill a milling groove for embedding the copper block on the PCB board. The size of the milling groove is larger than the size of the copper block to facilitate the copper block to be easily placed into the milling groove;

[0037] During the lamination process, the copper foil and the substrate are cleaned to remove surface dirt, grease, and other impurities. The copper foil is surface-treated, such as brownification, to form a uniform brown organic metal film on the copper surface, enhancing the bonding force between the copper surface and the prepreg. Stack multiple layers of copper foil, substrate material, and prepreg in sequence. During the stacking process, ensure that an appropriate amount of adhesive (such as the resin in the prepreg) is placed between each layer. Put the stacked materials into a laminator. Under the action of high temperature and high pressure, the resin in the prepreg melts and flows, filling the gaps between the layers. The resin forms a solid insulating layer during the curing process, tightly bonding the layers together. After lamination, take the materials out of the laminator and perform a cooling and curing treatment. Cooling and curing can ensure that the resin is completely cured, forming a stable structure.

[0038] Post-lamination treatment: Trim the edges after lamination to remove burrs, uneven parts, or excess adhesive, improving the appearance quality and dimensional accuracy of the product, and clean the laminated parts to remove surface dirt, grease, dust, and other impurities.

[0039] In step S2, during lamination, stack the copper foil, prepreg, PCB board substrate, prepreg, and copper foil from bottom to top in sequence, then use a laminator for lamination treatment, and remove the excess edge materials;

[0040] When conventionally embedding copper blocks, when putting the copper blocks into the board, it is difficult for the copper blocks to remain centered, and it is easy to cause the copper blocks to contact the board due to tilting, resulting in too small a gap between the copper blocks and the board. When the gap between the copper blocks and the board is too small, it is difficult for the resin to enter, and it is easy to form cavities, leading to reliability problems.

[0041] In step S2, since the size of the milled groove is larger than the size of the copper block, in order to ensure that the copper block remains centered when placed in the milled groove and prevent the copper block from tilting and contacting the inner wall of the milled groove, convex grooves are provided around the inner wall of the milled groove, and two convex grooves are provided on each inner wall surface of the milled groove. The convex grooves are cylindrical convex grooves with a radius of 5 mil to prevent damage to the copper block.

[0042] When milling the groove, place the laminated PCB board on the workbench of the milling machine and use a fixture to clamp and position it. Then start the milling machine and perform the processing of the milled groove by moving the milling cutter. During the milling process, closely monitor the movement trajectory of the milling cutter and the processing condition of the PCB board. After milling, use a suitable measuring tool to check the size and position accuracy of the milled groove.

[0043] S3. Embed copper blocks: Clean the groove surface of the milled groove, and paste a high-temperature resistant tape on one side of the milled groove. The high-temperature resistant tape fits tightly against the edge of the milled groove. Then put the copper block into the milled groove, making the copper block adhere to the high-temperature resistant tape to achieve the positioning of the copper block;

[0044] In step S3, for cleaning the groove surface of the milled groove, use a grinding machine to grind the groove surface of the milled groove to remove burrs and uneven parts on the groove surface.

[0045] When pasting the high-temperature resistant tape, make the width and length of the high-temperature resistant tape both larger than the size of the milled groove opening, and ensure that the high-temperature resistant tape is in full contact with the groove surface of the milled groove, ensuring that the high-temperature resistant tape is flat, without wrinkles and offsets.

[0046] In step S3, the distance between the protruding grooves at opposite positions on the inner wall of the milled groove is 2 mil larger than the size of the copper block. When the copper block is placed into the milled groove, the protruding grooves play a role in limiting the copper block, making the copper block located at a position close to the center inside the milled groove, and preventing the situation where the resin cannot be injected into the milled groove due to the contact between the copper block and the inner wall of the milled groove.

[0047] Gently align the copper block with the milled groove opening, ensure that the copper block is in close contact with the bottom of the milled groove, slowly place the copper block into the milled groove, avoiding excessive impact force or scratching the groove surface of the milled groove, and gently press the copper block with tape to fix its position. Ensure that the copper block is stable and does not shake in the groove, and the tape can provide sufficient fixing force.

[0048] S4. First vacuum resin plugging of holes: Use vacuum resin plugging equipment to inject resin into the milled groove from the side where the high-temperature resistant tape is not pasted, and cure the resin, then remove the high-temperature resistant tape on one side of the milled groove;

[0049] In step S4, during the first vacuum resin plugging of holes, make the resin ooze out at the position of the milled groove, then put the PCB board filled with resin into the oven, set the baking board parameters as 80℃ * 30min + 110℃ * 30min + 150℃ * 50min, and perform three-stage baking board curing treatment.

[0050] The resin can be any one of epoxy resin, polyester resin, phenolic resin, and polyurethane resin, where:

[0051] For epoxy resin, at a temperature of about 100℃, the curing time is usually 1 to 2 hours, and at 150℃, the curing time can be shortened to 30 minutes to 1 hour;

[0052] For polyester resin, at a temperature of 80℃ to 120℃, the curing time is generally 1 to 3 hours, and at high temperature (such as 150℃), the curing time may be 30 minutes to 1 hour;

[0053] For phenolic resin, at a temperature of 150℃, the curing time is usually 1 to 2 hours;

[0054] For polyurethane resin, at a temperature of 60℃ to 80℃, the curing time may be 1 to 3 hours, and at a higher temperature (such as 100℃), the time may be shortened.

[0055] During the first resin injection, place the PCB board on the workbench of the vacuum resin plugging equipment, ensure that the slot is aligned with the resin injection port, start from the side without tape, start the equipment, and inject the resin evenly and fully into the slot space. During the injection process, closely monitor the resin flow to ensure no bubbles are generated. If necessary, adjust the injection speed or vacuum degree to improve the filling effect.

[0056] S5. Second vacuum resin plugging: Use the vacuum resin plugging equipment to plug the resin into the milled slot from the other side of the milled slot, and cure the resin to make the resin tightly wrap the copper block.

[0057] In step S5, after removing the high-temperature resistant tape, make a ceramic grinding plate. After the ceramic grinding plate is completed, perform vacuum resin plugging again from the front and back of the PCB board respectively, so that the injected resin is in full contact with the cured resin, that is, make the resin fill the gap between the milled slot and the copper block.

[0058] Then put the PCB board into the oven, set the baking temperature of the board at 150 °C, and set the curing time to 0.5 h.

[0059] The second resin injection method and curing method are the same, so they will not be elaborated here.

[0060] S6. Grinding plate treatment: Use the grinding plate equipment to grind the PCB board to remove the residual resin on the surface of the PCB board that exceeds the surface during the vacuum resin plugging process, and complete the production of the embedded copper block.

[0061] In step S6, place the PCB board filled with resin on the workbench of the grinding plate equipment, make the surface of the PCB board flat and without deformation, and use a fixture to fix the PCB board. Start the grinding plate equipment, drive the ceramic grinding plate to move, and control the transmission speed of the ceramic grinding plate to remove the excess resin on the surface of the PCB board.

[0062] The manufacturing method of this embedded copper block has the following advantages:

[0063] 1. Affected by the stack structure, buried copper blocks can also be made using the stack structure of copper foil lamination.

[0064] 2. Cost savings. Laminating to make buried copper blocks requires making openings for all core boards and PP, and requires additional milling of the outer shape and laser milling of PP. The process of making buried copper blocks by vacuum plugging only requires one milling of the outer shape, and the cost of vacuum plugging is also slightly lower than that of laminating to make buried copper blocks. Moreover, the price of laminating to make buried copper blocks is related to the number of core boards and PP. As the number of layers increases, the relative price advantage of making buried copper blocks by vacuum plugging will be greater.

[0065] 3. The convex groove design is added to the milled slot design, making the copper block relatively more centered, and can meet the alignment requirements of some buried copper blocks.

[0066] 4. When making buried copper blocks with vacuum resin plug holes, since the copper blocks are fixed with tape first, the problem of copper block deviation is avoided, and the qualified rate of finished products can be improved to a certain extent.

[0067] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A new method for making an embedded copper block, characterized in that: The following steps are involved: S1. Material preparation: prepare materials for pre-embedded copper blocks on the circuit board, including copper blocks, PCB boards, high temperature resistant tapes, vacuum resins, grinding tools, and curing equipment; S2, lamination and milling processing: lamination and post-lamination processing of PCB boards to make the board surface flat without bubbles and impurities, and use a milling machine to mill out milling grooves for pre-embedded copper blocks on the PCB boards. The size of the milling grooves is larger than the size of the copper blocks; S3. Pre-embed copper block: clean the surface of the milling groove, and paste high temperature resistant tape on one side of the milling groove. The high temperature resistant tape is tightly attached to the edge of the milling groove. Then put the copper block into the milling groove, so that the copper block and the high temperature tape are adhered to achieve the positioning of the copper block. S4, first vacuum resin plugging: use vacuum resin plugging equipment to plug the resin into the milling groove from the side where the high temperature resistant tape is not pasted, and cure the resin, and then peel off the high temperature resistant tape on one side of the milling groove; S5. Second vacuum resin plugging: Use vacuum resin plugging equipment to plug the resin into the milling groove from the other side of the milling groove, and solidify the resin so that the resin tightly wraps the copper block; S6, grinding treatment: Use grinding equipment to grind the PCB board to remove the residual resin that exceeds the surface of the PCB board during the vacuum resin plugging process, and complete the production of the embedded copper block.

2. A method for making a new embedded copper block according to claim 1, characterized in that: In step S1, the high temperature resistant tape is a polyester film tape, the surface of the PCB board is flat and free of scratches and bubble defects, the grinding tool is a ceramic brush, and the curing equipment is an oven.

3. The method for making a new embedded copper block according to claim 1, characterized in that: In step S2, during lamination, copper foil, prepreg, PCB substrate, prepreg, copper foil are stacked in sequence from bottom to top, and then a laminator is used for lamination, and excess edge materials are removed; When milling the groove, place the laminated PCB board on the workbench of the milling machine and clamp it in place with a fixture, then start the milling machine and move the milling cutter to complete the milling process.

4. The method for making a new embedded copper block according to claim 1, characterized in that: In step S2, since the size of the milling groove is larger than the size of the copper block, in order to ensure that the copper block remains centered when placed in the milling groove and prevent the copper block from tilting and contacting the inner wall of the milling groove, convex grooves are set around the inner wall of the milling groove, and two convex grooves are set on each inner wall of the milling groove. The convex groove is set to be a cylindrical convex groove with a radius of 5 mil.

5. The method for making a new embedded copper block according to claim 1, characterized in that: In step S3, the milled groove surface is cleaned by grinding the milled groove surface with a grinder to remove burrs and uneven parts on the groove surface; When pasting the high temperature resistant tape, make sure that the width and length of the high temperature resistant tape are larger than the size of the milling groove, and the high temperature resistant tape is in full contact with the milling groove surface to ensure that the high temperature resistant tape is flat, without wrinkles and offset.

6. A new method for making an embedded copper block according to claim 4, characterized in that: In step S3, the spacing between the convex grooves located at relative positions on the inner wall of the milling groove is 2 mil larger than the size of the copper block. When the copper block is placed in the milling groove, the convex groove limits the copper block, so that the copper block is located near the center of the milling groove and prevents the resin from being injected into the milling groove due to contact between the copper block and the inner wall of the milling groove.

7. A new method for making an embedded copper block according to claim 1, characterized in that: In step S4, the first vacuum resin plugging is performed until oil comes out of the milling groove, and then the PCB board filled with resin is placed in an oven, and the baking parameters are set to 80℃*30min+110℃*30min+150℃*50min, and a three-stage baking curing process is performed.

8. The method for making a new embedded copper block according to claim 1, characterized in that: In step S5, the ceramic grinding plate is made after the high temperature resistant glue is torn off. After the ceramic grinding plate is completed, vacuum resin plugging is performed again from the front and back sides of the PCB board to make the injected resin fully contact with the cured resin, that is, the resin fills the gap between the milling groove and the copper block; Then put the PCB board into the oven, set the temperature of the baking plate at 150°C, and set the curing time to 0.5h.

9. The method for making a new embedded copper block according to claim 1, characterized in that: In step S6, the resin-filled PCB is placed on the workbench of the grinding equipment, the surface of the PCB is made flat and free of deformation, and the PCB is fixed with a clamp. The grinding equipment is started, the ceramic grinding plate is driven to move, and the transmission speed of the ceramic grinding plate is controlled to remove excess resin on the surface of the PCB.

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