Method of flattening copper blocks

Abstract

The application provides a work method for making copper block pressure bonding flat, which is applied to the manufacturing process of a buried copper block PCB board, and the manufacturing process at least comprises sequentially performed slotting, fusion, glue sticking, copper block placing, pressure bonding and post-processing procedures. The work method for making copper block pressure bonding flat provided by the application is characterized in that: S1 places a PCB stack, S2 applies a first-stage pressure P1 at low temperature, S3 applies a second-stage pressure P2 greater than the first-stage pressure at low temperature, S4 solidifies and bonds at high temperature, and S5 performs a post-processing procedure. The above procedures are cooperated with each other to perform stepped pressure bonding in a semi-cured sheet solid state without melting, the generated copper block misalignment angle can be corrected in advance, no additional copper block chamfering, aluminum foil covering and other processing procedures and auxiliary material input are needed, the copper block inclination, protrusion and unevenness problems are solved from the mechanical root, the copper block is completely flush with the board surface after pressure bonding, the grinding scrap is reduced, and the additional processing cost and auxiliary material consumption are saved.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing technology, and in particular to a method for pressing copper blocks flat. Background Technology

[0002] As electronic products continue to evolve towards multifunctionality and high performance, electronic components are becoming increasingly highly integrated. These highly integrated electronic components generate a significant amount of heat during operation. To effectively dissipate this heat and ensure the reliability and lifespan of electronic products, copper blocks are typically placed in the PCB board as heat sinks.

[0003] Currently, the typical manufacturing process for embedded copper block PCBs includes slotting, fusion, adhesive application, copper block placement, lamination, and post-processing. Among these, lamination is crucial for determining the final flatness of the copper block. However, in actual production, existing technologies often result in issues such as one side of the copper block being lower than the board surface, overall tilting, or localized bulging after lamination. This prevents subsequent grinding processes from effectively removing excess adhesive from the low-lying areas, leading to product scrap or downgrading. Research revealed that this problem primarily occurs during the transfer step after copper block placement and before lamination. Specifically, although the PCB stacked boards are bonded after the fusion process, they haven't undergone high-temperature curing, resulting in insufficient rigidity. During manual or mechanical transfer, operators typically grasp the boards from the edges. The middle portion of the board naturally sags due to its own weight, forming an arc; however, the copper block itself has sufficient rigidity and does not bend with the board, remaining flat. This mismatch in deformation causes the copper block to be misaligned relative to the groove on the board surface. One side of the copper block may protrude above the board surface, while the other side may sink into the groove. When the board is placed in the laminating equipment, this misalignment is "locked in." Even with subsequent pressure and heating, the pressure is buffered by the flowing resin as the prepreg gradually melts and becomes viscous during heating, failing to effectively "correct" the copper block back to the correct horizontal position. Ultimately, the copper block is cured in the PCB board in a tilted or convex state, resulting in permanent unevenness.

[0004] To address this issue, some improvements have been attempted in existing technologies, such as grooved bottom edges of the copper block or chamfered corners to improve the fit between the copper block and the groove; or adding coated aluminum foil or buffer film to the top and bottom of the plate during pressing to evenly distribute pressure. However, these solutions either increase additional processing steps and costs or require additional auxiliary materials, and fail to solve the problem at its fundamental mechanical mechanism.

[0005] Therefore, it is necessary to provide a method for pressing copper blocks flat to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a method for pressing copper blocks flat, which solves the problems of adding extra processing steps and costs, requiring additional auxiliary materials, and failing to address the fundamental mechanical mechanism.

[0007] To solve the above-mentioned technical problems, the present invention provides a method for flattening copper blocks by pressing them together, which is applied in the manufacturing process of copper-embedded PCB boards. This manufacturing process includes at least the following sequential steps: slotting, fusion, adhesive application, copper block placement, pressing, and post-processing. The pressing step includes the following steps: S1. The PCB stack formed after the grooving process, fusion process, adhesive application process and copper block placement process is placed in the laminating equipment. The PCB stack has a groove for accommodating the copper block, and the copper block has been placed in the groove. S2. In the pressing section of the laminating equipment, and before the temperature of the PCB stacked board rises to the melting temperature of the prepreg, the first pressure P1 is applied so that the copper block protruding from the board surface is initially pressed into the tank under the solid condition of the prepreg not melting. S3. After applying the first stage pressure P1, and before the temperature of the PCB stacked board rises to the melting temperature of the prepreg, apply the second stage pressure P2 to further press the copper block into the groove and make it flush with the board surface under the solid condition of the prepreg not melting. The second stage pressure P2 is greater than the first stage pressure P1. S4. After applying the second stage pressure P2, heat and press the PCB stack according to the preset heating curve to melt and solidify the prepreg and fix the copper block in the PCB stack. S5. After pressing, the following post-processing steps are performed in sequence: peeling off the adhesive, hitting the target, trimming the edges, and grinding.

[0008] Preferably, in step S2, the first stage pressure P1 is 10-20 kg / cm², and the pressure holding time is 10-60 seconds; in step S3, the second stage pressure P2 is 20-30 kg / cm², and the pressure holding time is 10-60 seconds.

[0009] Preferably, one or more intermediate pressures are applied between step S2 and step S3, with the pressure value of each segment increasing in a stepwise manner, the increment being 2 to 5 kg / cm², and the holding time of each segment being 10 to 60 seconds.

[0010] Preferably, the pressing equipment is a vacuum press, and both steps S2 and S3 are performed under the condition that the temperature of the PCB stack is lower than the glass transition temperature of the prepreg.

[0011] Preferably, the grooving process includes creating a groove on the substrate and the prepreg that matches the shape of the copper block; the fusion process fuses the substrate and the prepreg together; the adhesive application process applies heat-resistant adhesive tape to the bottom or side of the groove to support the copper block; and the copper block placement process places the copper block in the groove.

[0012] Preferably, after the copper block placement process and before the pressing process, a transfer step is also included. In the transfer step, a misalignment angle is generated between the copper block and the PCB stack. The first pressure P1 and the second pressure P2 applied in steps S2 and S3 are used to eliminate the misalignment angle in the early stage of pressing.

[0013] Preferably, the transfer step requires the use of a transfer vehicle, which includes a pallet 1, and side guard components 4 are provided around the top of the pallet 1.

[0014] Preferably, the top of the tray 1 is provided with four sliding grooves 2, and each side of the four sliding grooves 2 is provided with multiple positioning holes 3, and the multiple positioning holes 3 are all located on the top of the tray 1.

[0015] Preferably, the side guard assembly 4 includes a baffle 41, a slide plate 42, a pressing plate 43, a fixing plate 44, two positioning rods 45, a moving groove 46, a sliding rod 47, a spring 48, and a moving plate 49. The baffle 41 is disposed on the top of the tray 1. The slide plate 42 is slidably connected to the inside of the baffle 41. The pressing plate 43 is fixedly installed on the top of the slide plate 42. The fixing plate 44 is fixedly installed on the bottom of the slide plate 42. The two positioning rods 45 are respectively fixedly installed at both ends of the top of the fixing plate 44. The moving groove 46 is opened inside the baffle 41. The sliding rod 47 is fixedly installed on the inner side of the moving groove 46. The spring 48 is sleeved on the outer side of the sliding rod 47. The moving plate 49 is slidably connected to the outer side of the sliding rod 47 and is located on top of the spring 48. One end of the moving plate 49 is fixedly installed on the side of the slide plate 42. The top of the positioning rod 45 is inserted into the bottom of the positioning hole 3.

[0016] Preferably, a support frame 5 is fixedly installed around the bottom of the tray 1.

[0017] Compared with related technologies, the method for pressing copper blocks flat provided by the present invention has the following beneficial effects: This invention provides a method for flattening copper blocks by pressing them together. The method involves a series of steps: S1 placing the PCB stack, S2 applying a first-stage pressure P1 at a low temperature, S3 applying a second-stage pressure P2 at a low temperature, S4 heating and curing, and S5 post-processing. By applying pressure in a stepwise manner while the semi-cured sheet is in a solid, unmelted state, the misalignment angle of the copper blocks caused during transport can be corrected in advance. This eliminates the need for additional processing steps and auxiliary materials such as chamfering of the copper blocks and covering with aluminum foil. It solves the problems of tilting, protrusion, and unevenness of the copper blocks from a mechanical perspective. After pressing, the copper blocks are completely flush with the board surface, reducing grinding scrap and saving additional processing costs and auxiliary material consumption. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a preferred embodiment of a method for pressing and flattening copper blocks according to the present invention. Figure 2 for Figure 1 The diagram shows another perspective of the structure; Figure 3 for Figure 1 The diagram shows a cross-sectional view of the side guard assembly. Figure 4 for Figure 3 The enlarged diagram of part A is shown.

[0019] The following are the labels in the diagram: 1. Tray, 2. Slide, 3. Positioning hole, 4. Side guard assembly, 41. Baffle, 42. Slide plate, 43. Pressing plate, 44. Fixing plate, 45. Positioning rod, 46. Moving groove, 47. Slide rod, 48. Spring, 49. Moving plate, 5. Support frame. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Please refer to the following: Figure 1 , Figure 2 , Figure 3 , Figure 4 ,in, Figure 1 This is a schematic diagram of a preferred embodiment of a method for pressing and flattening copper blocks according to the present invention. Figure 2 for Figure 1 The diagram shows another perspective of the structure; Figure 3 for Figure 1 The diagram shows a cross-sectional view of the side guard assembly. Figure 4 for Figure 3 The enlarged diagram of part A is shown.

[0022] A method for flattening copper blocks during the manufacturing process of embedded copper PCBs includes at least the following sequential steps: slotting, fusion, adhesive application, copper block placement, pressing, and post-processing. The pressing step includes the following steps: S1. The PCB stack formed after the grooving process, fusion process, adhesive application process and copper block placement process is placed in the laminating equipment. The PCB stack has a groove for accommodating the copper block, and the copper block has been placed in the groove. S2. In the pressing section of the laminating equipment, and before the temperature of the PCB stacked board rises to the melting temperature of the prepreg, the first pressure P1 is applied so that the copper block protruding from the board surface is initially pressed into the tank under the solid condition of the prepreg not melting. S3. After applying the first stage pressure P1, and before the temperature of the PCB stacked board rises to the melting temperature of the prepreg, apply the second stage pressure P2 to further press the copper block into the groove and make it flush with the board surface under the solid condition of the prepreg not melting. The second stage pressure P2 is greater than the first stage pressure P1. S4. After applying the second stage pressure P2, heat and press the PCB stack according to the preset heating curve to melt and solidify the prepreg and fix the copper block in the PCB stack. S5. After pressing, the following post-processing steps are performed in sequence: peeling off the adhesive, hitting the target, trimming the edges, and grinding.

[0023] In step S2, the first stage pressure P1 is 10-20 kg / cm², and the pressure holding time is 10-60 seconds; in step S3, the second stage pressure P2 is 20-30 kg / cm², and the pressure holding time is 10-60 seconds.

[0024] Between step S2 and step S3, one or more intermediate pressures are applied, with each pressure value increasing in a stepwise manner, the increment being 2 to 5 kg / cm², and the holding time for each pressure segment being 10 to 60 seconds.

[0025] The pressing equipment is a vacuum press, and both steps S2 and S3 are performed under the condition that the temperature of the PCB stack is lower than the glass transition temperature of the prepreg.

[0026] The grooving process includes creating grooves on the substrate and prepreg that match the shape of the copper block; the fusion process fuses the substrate and prepreg together; the adhesive application process applies heat-resistant tape to the bottom or side of the groove to support the copper block; and the copper block placement process places the copper block in the groove.

[0027] After the copper block placement process and before the pressing process, a transfer step is also included. In the transfer step, a misalignment angle is generated between the copper block and the PCB stack. The first stage pressure P1 and the second stage pressure P2 applied in steps S2 and S3 are used to eliminate the misalignment angle in the early stage of pressing.

[0028] The transfer step requires the use of a transfer vehicle, which includes a pallet 1, and side guard components 4 are provided around the top of the pallet 1.

[0029] The top of the tray 1 is provided with four sliding grooves 2, and multiple positioning holes 3 are provided on both sides of the four sliding grooves 2. The multiple positioning holes 3 are all located on the top of the tray 1.

[0030] The side baffle assembly 4 includes a baffle 41, a slide plate 42, a pressing plate 43, a fixing plate 44, two positioning rods 45, a moving groove 46, a sliding rod 47, a spring 48, and a moving plate 49. The baffle 41 is disposed on the top of the tray 1. The slide plate 42 is slidably connected to the inside of the baffle 41. The pressing plate 43 is fixedly installed on the top of the slide plate 42. The fixing plate 44 is fixedly installed on the bottom of the slide plate 42. The two positioning rods 45 are respectively fixedly installed at both ends of the top of the fixing plate 44. The moving groove 46 is opened inside the baffle 41. The sliding rod 47 is fixedly installed on the inner side of the moving groove 46. The spring 48 is sleeved on the outer side of the sliding rod 47. The moving plate 49 is slidably connected to the outer side of the sliding rod 47 and is located on top of the spring 48. One end of the moving plate 49 is fixedly installed on the side of the slide plate 42. The top of the positioning rod 45 is inserted into the bottom of the positioning hole 3.

[0031] Support frames 5 are fixedly installed around the bottom of the tray 1.

[0032] Working principle of the transfer carrier: After the copper block placement process is completed, the PCB stack needs to be transferred from the copper block placement station to the laminating equipment. At this time, the operator places the PCB stack on top of the tray 1. The side baffles 4 set around the tray 1 are used to limit the four sides of the PCB stack to prevent the PCB stack from sliding horizontally on the tray 1 during the transfer process.

[0033] Before use, the side baffle assembly 4 is first adjusted according to the size of the PCB stack. The operator presses down the pressing plate 43, which drives the sliding plate 42 to slide downward along the inside of the baffle 41. The sliding plate 42 drives the fixing plate 44 and the two positioning rods 45 to move downward simultaneously, so that the top of the two positioning rods 45 disengages from the positioning hole 3, releasing the lock between the baffle 41 and the tray 1. At the same time, the sliding plate 42 drives the moving plate 49 to slide downward along the moving groove 46 and compress the spring 48. At this time, the baffle 41 can slide freely along the sliding groove 2 on the top of the tray 1. The operator slides the baffle 41 to a position close to the edge of the PCB stack.

[0034] After adjustment, release the pressing plate 43. The spring 48 releases its elastic potential energy, pushing the moving plate 49 to slide upwards along the slide rod 47 to reset. The moving plate 49 drives the sliding plate 42 to move upwards. The sliding plate 42 drives the fixed plate 44 and the two positioning rods 45 to move upwards synchronously, so that the tops of the two positioning rods 45 are inserted into the corresponding positioning holes 3, locking the baffle 41 in that position. The four side baffle assemblies 4 clamp and position the PCB stack from four sides, effectively preventing the PCB stack from sliding or shifting horizontally on the tray 1 during transportation.

[0035] During the transfer process, the baffle 41 supports the four sides of the PCB stack, keeping the PCB stack in a horizontal position during transfer. This prevents the middle part of the board from drooping due to its own weight when the operator grabs it from the two sides of the board, thus preventing the copper block from being misaligned relative to the board surface groove.

[0036] The working principle of the method for pressing copper blocks flat provided by this invention is as follows: The method of this invention is applied to the manufacturing process of copper-embedded PCB boards, which includes, in sequence, a grooving process, a fusion process, an adhesive application process, a copper block placement process, a pressing process, and a post-processing process. Among these, the pressing process is the core improvement of this invention.

[0037] After the copper block placement process is completed and before the lamination process begins, the PCB stack needs to be transferred from the copper block placement station to the lamination equipment. During the transfer process, because the fused PCB stack has not yet undergone high-temperature curing, its rigidity is insufficient. When the operator grabs the board from both sides of the edge, the middle part of the board sags due to its own weight, forming an arc. However, the copper block itself is rigid and remains straight, causing a misalignment angle between the copper block and the groove on the board surface. One side of the copper block is higher than the board surface, and the other side is lower than the board surface. If the conventional process of heating and laminating is used directly, the prepreg gradually melts and becomes a viscous flow during the heating process. At this time, the pressure applied will be buffered by the flowing resin and cannot effectively correct the misalignment angle of the copper block. In the end, the copper block is cured in an inclined state inside the board.

[0038] The lamination process of this invention eliminates the misalignment angle by applying mechanical pressure in stages before heating, while the prepreg is still in a solid state. Specifically, the PCB stack is placed in the pressing section of the lamination equipment (vacuum laminator). Before the temperature rises to the melting temperature of the prepreg (below its glass transition temperature), a first stage of pressure P1 (10-20 kg / cm², holding pressure for 10-60 seconds) is applied, so that the copper block protruding from the board surface is initially pressed into the groove while the prepreg is in a solid state, thus initially eliminating the misalignment angle. Subsequently, a second stage of pressure P2 (20-30 kg / cm², holding pressure for 10-60 seconds) is applied. The second stage of pressure is greater than the first stage of pressure, so that the copper block is further pressed into the groove while the prepreg is in a solid state and completely flush with the board surface. One or more intermediate pressures can be applied between P1 and P2 as needed, with each pressure increasing in a stepwise manner (step 2-5 kg / cm²), so that the copper block is gradually and smoothly pressed into the tank, avoiding damage to the copper block or the plate surface caused by applying too much pressure at once.

[0039] Because the prepreg remains solid and does not melt or flow when pressure is applied in the first and second stages (and the middle stage), the mechanical pressure can be directly and effectively transmitted to the copper block, pushing it to overcome the misalignment angle and fully embed it into the groove, making the upper surface of the copper block flush with the board surface. After completing the segmented pressure correction under low-temperature solid conditions, the PCB stack is then heated and pressed according to a preset temperature rise curve, causing the prepreg to melt and solidify, fixing the copper block in the PCB stack. At this point, the copper block is in the correct horizontal position and will remain flat after solidification. After pressing, the adhesive is removed, the surface is punctured, the edges are trimmed, and the surface is ground to obtain a PCB board with a flat copper block.

[0040] Compared with related technologies, the method for pressing copper blocks flat provided by the present invention has the following beneficial effects: The process involves a series of steps: S1 for placing the PCB stack, S2 for applying the first stage of pressure (P1) at a low temperature, S3 for applying the second stage of pressure (P2) at a low temperature, S4 for heating and curing, and S5 for post-processing. These steps work together to apply pressure in a stepwise manner while the prepreg is in a solid, unmelted state. This allows for the correction of misalignment of the copper blocks during transport, eliminating the need for additional processing steps and materials such as chamfering or aluminum foil coating. This addresses the issue of tilting, protrusion, and unevenness of the copper blocks from a mechanical perspective. After pressing, the copper blocks are completely flush with the board surface, reducing grinding waste and saving on additional processing costs and material consumption.

[0041] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for flattening copper blocks during the manufacturing process of embedded copper block PCBs, the manufacturing process comprising at least the following sequential steps: slotting, fusion, adhesive application, copper block placement, pressing, and post-processing. The method is characterized by... The pressing process includes the following steps: S1. The PCB stack formed after the grooving process, fusion process, adhesive application process and copper block placement process is placed in the laminating equipment. The PCB stack has a groove for accommodating the copper block, and the copper block has been placed in the groove. S2. In the pressing section of the laminating equipment, and before the temperature of the PCB stacked board rises to the melting temperature of the prepreg, the first pressure P1 is applied so that the copper block protruding from the board surface is initially pressed into the tank under the solid condition of the prepreg not melting. S3. After applying the first stage pressure P1, and before the temperature of the PCB stacked board rises to the melting temperature of the prepreg, apply the second stage pressure P2 to further press the copper block into the groove and make it flush with the board surface under the solid condition of the prepreg not melting. The second stage pressure P2 is greater than the first stage pressure P1. S4. After applying the second stage pressure P2, heat and press the PCB stack according to the preset heating curve to melt and solidify the prepreg and fix the copper block in the PCB stack. S5. After pressing, perform the following post-processing steps in sequence: peeling off the adhesive, hitting the target, trimming the edges, and grinding.

2. The method for pressing and flattening copper blocks according to claim 1, characterized in that, In step S2, the first stage pressure P1 is 10-20 kg / cm², and the pressure holding time is 10-60 seconds; in step S3, the second stage pressure P2 is 20-30 kg / cm², and the pressure holding time is 10-60 seconds.

3. The method for pressing copper blocks flat according to claim 1, characterized in that, Between step S2 and step S3, one or more intermediate pressures are applied, with the pressure value of each segment increasing in a stepwise manner, the increment being 2 to 5 kg / cm², and the holding time of each segment being 10 to 60 seconds.

4. The method for pressing and flattening copper blocks according to claim 1, characterized in that, The pressing equipment is a vacuum press, and both steps S2 and S3 are performed under the condition that the temperature of the PCB stack is lower than the glass transition temperature of the prepreg.

5. The method for pressing a copper block flat according to claim 1, characterized in that, The grooving process includes creating grooves on the substrate and prepreg that match the shape of the copper block; the fusion process fuses the substrate and prepreg together; the adhesive application process applies heat-resistant tape to the bottom or side of the groove to support the copper block; and the copper block placement process places the copper block in the groove.

6. The method for pressing and flattening copper blocks according to claim 1, characterized in that, After the copper block placement process and before the pressing process, a transfer step is also included. In the transfer step, a misalignment angle is generated between the copper block and the PCB stack. The first stage pressure P1 and the second stage pressure P2 applied in steps S2 and S3 are used to eliminate the misalignment angle in the early stage of pressing.

7. The method for pressing and flattening copper blocks according to claim 6, characterized in that, The transfer step requires the use of a transfer vehicle, which includes a pallet 1, and side guard components 4 are provided around the top of the pallet 1.

8. The method for pressing and flattening copper blocks according to claim 7, characterized in that, The top of the tray 1 is provided with four sliding grooves 2, and multiple positioning holes 3 are provided on both sides of the four sliding grooves 2. The multiple positioning holes 3 are all located on the top of the tray 1.

9. A method for pressing copper blocks flat according to claim 8, characterized in that, The side baffle assembly 4 includes a baffle 41, a slide plate 42, a pressing plate 43, a fixing plate 44, two positioning rods 45, a moving groove 46, a sliding rod 47, a spring 48, and a moving plate 49. The baffle 41 is disposed on the top of the tray 1. The slide plate 42 is slidably connected to the inside of the baffle 41. The pressing plate 43 is fixedly installed on the top of the slide plate 42. The fixing plate 44 is fixedly installed on the bottom of the slide plate 42. The two positioning rods 45 are respectively fixedly installed at both ends of the top of the fixing plate 44. The moving groove 46 is opened inside the baffle 41. The sliding rod 47 is fixedly installed on the inner side of the moving groove 46. The spring 48 is sleeved on the outer side of the sliding rod 47. The moving plate 49 is slidably connected to the outer side of the sliding rod 47 and is located on top of the spring 48. One end of the moving plate 49 is fixedly installed on the side of the slide plate 42. The top of the positioning rod 45 is inserted into the bottom of the positioning hole 3.

10. A method for pressing copper blocks flat according to claim 9, characterized in that, Support frames 5 are fixedly installed around the bottom of the tray 1.

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