Manufacturing method of copper-block-embedded double-sided printed circuit board

Abstract

The invention discloses a method for manufacturing a copper-block-embedded double-sided printed circuit board, which comprises the following steps of: slotting a core board, and controlling the slot precision within + / -50 microns; the core plate is placed on a marble platform, the copper blocks are placed in the groove holes, and it is ensured that the flatness of the copper blocks is within + / -12.7 micrometers; plugging the hole with vacuum resin, and pasting a high-temperature adhesive tape to fix the copper block after plugging the hole; the baking plate is vertically placed or fixed by a special jig; a UC type coating drilling tool is used for drilling, a segmented drilling mode is adopted to cope with hardness differences of different materials, and the service life of a drill bit is dynamically set and strictly controlled according to the diameter of the drilling tool, the thickness of a copper block and a laminated plate structure; hole metallization is carried out, full-board electroplating is carried out, and it is ensured that the hole copper thickness is 25-30 [mu] m; manufacturing an outer-layer circuit by adopting a high-precision pattern transfer process; and carrying out surface treatment, molding and electrical testing. According to the manufacturing method of the copper-block-embedded double-sided printed circuit board, the displacement risk of the copper block in a double-sided board structure is reduced by 15% through the measures of marble platform flatness control, vertical board baking and the like, and the problems of copper block fixing, precise drilling and interface reliability are systematically solved.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, specifically to a method for manufacturing a double-sided printed circuit board with embedded copper blocks. Background Technology

[0002] In high-power applications such as communication power supplies and automotive electronics, double-sided PCBs are widely used due to their simple structure and low cost. However, the large amount of heat generated by power devices during operation requires an effective heat dissipation path. Embedding copper blocks into the double-sided PCB is an effective way to improve its heat dissipation capacity. However, this technology faces serious challenges: First, adding thick copper blocks to a simple double-sided structure can easily lead to board warping, copper block displacement, or incomplete resin filling during lamination due to uneven stress. Second, when drilling holes in the copper blocks, the sudden change in material hardness can easily cause problems such as hole misalignment, rapid drill wear, and poor hole wall quality, seriously affecting the reliability of the metallized holes. Current technology lacks a complete process solution for double-sided PCB structures that can systematically solve the problem from embedded block fixation to high-reliability interconnection.

[0003] Therefore, the purpose of this invention is to provide a method for manufacturing a double-sided printed circuit board with embedded copper blocks to solve the above-mentioned technical problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for manufacturing a double-sided printed circuit board with embedded copper blocks. By optimizing the process flow and process parameters, the problems of copper block fixing, precision drilling and interface reliability are systematically solved.

[0005] The technical solution of this invention is:

[0006] A method for manufacturing a double-sided printed circuit board with embedded copper blocks includes the following steps:

[0007] Step S1: Grooving of the core board, controlling the groove accuracy within ±50μm;

[0008] Step S2: Place the core board on the marble platform and place the copper block in the slot, ensuring that the flatness of the copper block is within ±12.7μm;

[0009] Step S3: Vacuum resin plugging of the hole, followed by application of high-temperature tape to fix the copper block.

[0010] Step S4, baking plate, is placed vertically or fixed with a special fixture to prevent the copper block from shifting due to gravity or stress before the resin cures;

[0011] Step S5, drilling: When drilling holes in the copper block, a UC-type coated drill bit is used, and a segmented drilling method is adopted to cope with the hardness differences of different materials; and the drill bit life is dynamically set and strictly controlled according to the drill bit diameter, copper block thickness and stacked plate structure through trial drilling and hole wall quality monitoring.

[0012] Step S6: Hole metallization, full-board electroplating, ensuring the copper thickness of the holes is 25-30μm;

[0013] Step S7: Use high-precision pattern transfer technology to fabricate the outer layer circuitry;

[0014] Step S8: Surface treatment, followed by molding and electrical testing.

[0015] Furthermore, in step S3, the vacuum resin plugging hole adopts a double-sided plugging method.

[0016] Furthermore, in step S5, the segmented drilling process adopts a slow-then-fast approach, specifically:

[0017] The first stage involves drilling copper blocks, using a low-speed, slow-feed method.

[0018] The second stage involves drilling the substrate using a high-speed, rapid-feed method.

[0019] Furthermore, in step S7, the tolerance of the RF circuit is controlled at +25.4μm.

[0020] Furthermore, it also includes steps for testing product reliability, specifically including thermal stress testing, reflow soldering testing, and routine reliability testing.

[0021] Furthermore, the thermal stress test method is as follows: immerse the finished board in a tin bath at 288°C for 10 seconds, repeat 3-5 times, and then cut it to check the interface between the copper block and the resin. Delamination or cracks are not allowed.

[0022] Furthermore, the reflow soldering test method is as follows: simulate the actual assembly process, so that the finished board undergoes 3 reflow solderings, and the peak furnace temperature needs to reach 250-265℃. After the test, slice it again to confirm that the position of the copper block and the interface are free from delamination, cracks and displacement.

[0023] Furthermore, routine reliability tests include high and low temperature cycling tests, salt spray tests, ion contamination tests, and solder mask adhesion tests.

[0024] Compared with the prior art, the method for manufacturing double-sided printed circuit boards with embedded copper blocks provided by the present invention has the following advantages:

[0025] The method for manufacturing double-sided printed circuit boards with embedded copper blocks provided by the present invention systematically solves the problem of unstable copper block fixation in double-sided board structures by combining measures such as placing copper blocks on a marble platform to control the flatness of the copper blocks, fixing the copper blocks with high-temperature tape after vacuum resin plugging, and placing the board vertically during baking. This reduces the risk of copper block displacement in double-sided board structures by 15%.

[0026] II. The method for manufacturing double-sided printed circuit boards with embedded copper blocks provided by the present invention effectively improves the quality and consistency of drilling on copper blocks by adopting segmented drilling combined with UC-type coated drill bit technology and strictly controlling the life of drill bit, thus ensuring the high reliability of metallized holes.

[0027] Second, the method for manufacturing double-sided printed circuit boards with embedded copper blocks provided by this invention suggests a set of product verification standards that match the manufacturing process, making product quality controllable and predictable, and able to meet the stringent requirements of high-end fields such as automobiles and communications for multi-layer heat sinks. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below.

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] A method for manufacturing a double-sided printed circuit board with embedded copper blocks includes the following steps:

[0031] Step S1: Grooving of the core board, controlling the groove accuracy within ±50μm, and ensuring that the groove is free of burrs and flash.

[0032] Step S2: Place the core board on the marble platform and place the copper block in the slot, ensuring that the flatness of the copper block is within ±12.7μm;

[0033] In this embodiment, taking a core board with a thickness of 0.762mm as an example, the copper block thickness is 0.8mm, wherein the copper block thickness tolerance is +0.03mm and the length and width tolerance is ±0.1mm.

[0034] Step S3: Vacuum resin plugging of the hole, followed by application of high-temperature tape to fix the copper block.

[0035] If the TP2900S-F2 special vacuum plugging resin from KEDING is used for plugging, high-temperature tape should be applied immediately after plugging to fix the copper block and prevent it from sliding during subsequent baking; preferably, the vacuum resin plugging is done in a double-sided plugging manner to ensure that the resin plugging is full.

[0036] Step S4, baking plate: Place the plate vertically in the oven or use a professional fixture to fix it to prevent the copper block from shifting due to gravity or stress before the resin cures; and bake at 150°C for 60 minutes to allow the resin to fully cure.

[0037] Step S5: Drilling. Use a UC-type coated drill bit and adopt a segmented drilling method to cope with the hardness differences of different materials. Based on the drill bit diameter, copper block thickness, and stacked board structure, dynamically set and strictly control the drill bit life through test drilling and hole wall quality monitoring to ensure hole wall quality. For example, when drilling a Φ0.3mm drill bit on a single copper block, the life is usually no more than 50 holes. Before drilling, the expansion and contraction of the target hole on the board must be measured, and then the drill tape is made.

[0038] The segmented drilling process employs a slow-then-fast approach to address the hardness differences between different materials. Specifically:

[0039] The first stage involves drilling copper blocks using a low-speed, slow-feed method, such as a speed of 120K rpm and a feed rate of 1.2 m / min.

[0040] In the second stage, the substrate is drilled using a high-speed, fast-feed method. Once the copper block is drilled through, the speed is immediately switched to 180Krpm and the feed rate is 2.4m / min to drill the remaining FR4 section.

[0041] Step S6, hole metallization, full board electroplating, ensuring that the copper thickness of the hole is 25-30μm, to provide a reliable channel for current transmission;

[0042] Step S7: Use a high-precision pattern transfer process to fabricate the outer layer circuitry, and control the tolerance of the RF circuitry within +25.4μm; for example, use laser direct imaging (LDI) or high-alignment-precision film exposure to fabricate the outer layer circuitry.

[0043] Step S8: Surface treatment, followed by molding and electrical testing.

[0044] To verify and ensure the product quality of double-sided circuit boards with embedded copper blocks manufactured using the above method, the following reliability testing requirements are adopted:

[0045] The thermal stress test method is as follows: Immerse the finished board in a tin bath at 288℃ for 10 seconds, repeat 3-5 times, and then cut it to check the interface between the copper block and the resin. Delamination or cracks are not allowed.

[0046] The reflow soldering test method is to simulate the actual assembly process and make the finished board undergo three reflow soldering cycles. The peak furnace temperature needs to reach 250-265℃. After the test, the board is sliced ​​again to confirm that the position of the copper block and the interface are free from delamination, cracks, and displacement.

[0047] Routine reliability tests include high and low temperature cycling tests, salt spray tests, ion contamination tests (requirement <1.0 μgNaCl / cm²), and solder mask adhesion tests.

[0048] The manufacturing method and product control method of the double-sided printed circuit board with embedded copper blocks of the present invention show that the copper block interface is intact and all performance meets the standards.

[0049] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations made to these embodiments without departing from the principles and spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a double-sided printed circuit board with embedded copper blocks, characterized in that, Includes the following steps: Step S1: Grooving of the core board, controlling the groove accuracy within ±50μm; Step S2: Place the core board on the marble platform and place the copper block in the slot, ensuring that the flatness of the copper block is within ±12.7μm; Step S3: Vacuum resin plugging of the hole, followed by application of high-temperature tape to fix the copper block. Step S4, baking plate, is placed vertically or fixed with a special fixture to prevent the copper block from shifting due to gravity or stress before the resin cures; Step S5: Drilling. Use a UC-type coated drill bit and adopt a segmented drilling method to cope with the hardness differences of different materials. Based on the drill bit diameter, copper block thickness and stacked plate structure, dynamically set and strictly control the drill bit life through test drilling and hole wall quality monitoring. Step S6: Hole metallization, full-board electroplating, ensuring the copper thickness of the holes is 25-30μm; Step S7: Use high-precision pattern transfer technology to fabricate the outer layer circuitry; Step S8: Surface treatment, followed by molding and electrical testing.

2. The method for manufacturing a double-sided printed circuit board with embedded copper blocks according to claim 1, characterized in that, In step S3, the vacuum resin plugging hole is plugged using a double-sided plugging method.

3. The method for manufacturing a double-sided printed circuit board with embedded copper blocks according to claim 1, characterized in that, In step S5, the segmented drilling process adopts a slow-then-fast approach, specifically: The first stage involves drilling copper blocks, using a low-speed, slow-feed method. The second stage involves drilling the substrate using a high-speed, rapid-feed method.

4. The method for manufacturing a double-sided printed circuit board with embedded copper blocks according to claim 1, characterized in that, In step S7, the tolerance of the RF circuit is controlled at +25.4μm.

5. The method for manufacturing a double-sided printed circuit board with embedded copper blocks according to claim 1, characterized in that, It also includes steps for testing product reliability, specifically thermal stress testing, reflow soldering testing, and routine reliability testing.

6. The method for manufacturing a double-sided printed circuit board with embedded copper blocks according to claim 5, characterized in that, The thermal stress test method is as follows: Immerse the finished board in a tin bath at 288℃ for 10 seconds, repeat 3-5 times, and then cut it to check the interface between the copper block and the resin. Delamination or cracks are not allowed.

7. The method for manufacturing a double-sided printed circuit board with embedded copper blocks according to claim 5, characterized in that, The reflow soldering test method is to simulate the actual assembly process and make the finished board undergo three reflow soldering cycles. The peak furnace temperature needs to reach 250-265℃. After the test, the board is sliced ​​again to confirm that the position of the copper block and the interface are free from delamination, cracks, and displacement.

8. The method for manufacturing a double-sided printed circuit board with embedded copper blocks according to claim 5, characterized in that, Routine reliability testing includes high and low temperature cycling tests, salt spray tests, ion contamination tests, and solder mask adhesion tests.