Manufacturing method of copper block-embedded PCB (Printed Circuit Board)

Abstract

The invention discloses a manufacturing method of a PCB (Printed Circuit Board) embedded with a copper block, which comprises the following steps of: manufacturing the copper block according to the size of a milling groove of the PCB; milling the core plate and the PP sheet corresponding to the copper block embedding position; embedding a copper block; performing press fit; ceramic plate grinding is conducted, and residual glue on the surface of the copper block is removed; performing laser ablation and drilling; and electroplating and post-process. According to the manufacturing method of the PCB embedded with the copper block, the flatness of the copper block and the board surface and the surface quality of the copper block can be improved, so that the quality of the PCB embedded with the copper block is improved.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board manufacturing, and in particular to a method for manufacturing a copper-buried PCB board. Background Art

[0002] As electronic products become smaller and smaller, the size of PCB (printed circuit board) is also constantly shrinking, and the circuit design is becoming more and more intensive. As the power density of components increases, the heat dissipation of PCB is too large, which affects the service life, aging and even failure of components. Based on the development of new generation information technology, energy-saving and new energy vehicles, power equipment and other fields, the solution to the heat dissipation problem is imminent. At present, there are many ways to solve the heat dissipation problem of PCB. One of the effective ways is to directly bury a metal copper block with high thermal conductivity inside the printed board.

[0003] The copper block embedding process is to mill the core board, slot the PP sheet, and embed the copper block in the slotted core board and PP sheet during the lamination process. Since the copper block and the chip are in contact to dissipate heat, the copper block and the board surface need to be highly flat. However, in the actual production process, there is a certain height difference between the copper block and the board surface after lamination, which affects the heat dissipation effect of the PCB board.

[0004] The object of the present invention is to provide a manufacturing process for a PCB board with buried copper blocks, so as to improve the flatness of the copper blocks and the board surface. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for manufacturing a copper block buried PCB board, which can improve the flatness of the copper block and the board surface and the surface quality of the copper block, thereby improving the quality of the copper block buried PCB board.

[0006] The technical solution of the present invention is as follows:

[0007] A method for manufacturing a copper-buried PCB board comprises the following steps:

[0008] Step S1, making a copper block according to the size of the PCB milling groove;

[0009] Step S2, corresponding to the position where the copper block is buried, the core plate and the PP sheet are milled, and the copper block is buried in a through-burying or blind-burying manner, wherein the core plate includes:

[0010] Core board gong belt design: 8mil copper is cut on one side of the inner and outer layers to prevent burrs from rolling up when milling the core board. If the slot wall where the core board slot contacts the copper block is not copper-plated, the size of the core board slot is 4.5mil larger than the original copper block slot size; if the slot wall where the core board slot contacts the copper block is copper-plated, the size of the core board slot is 4.5mil larger than the original copper block slot size (4.5mil + copper plating thickness).

[0011] Milling core board: Punch out positioning holes, the thickness of the stacked boards is ≤3.0mm, lay the same size of light board on the core board as the cover board, adopt the combination of rough milling and fine milling, each slot is independently divided and compensated separately, the cutting speed of the core board close to the outer layer is set to 0.3m / min, and the cutting speed of other core boards is controlled according to the rough milling parameters, so that the core board slot size accuracy is ≤±3mil;

[0012] Milling PP sheet includes:

[0013] PP sheet gong belt design: When the copper block is buried blindly, the PP sheet in contact with the bottom of the copper block is not slotted; when the copper table is buried, the PP sheet in contact with the stepped surface of the copper block is slotted according to the size of the small copper table; the slot size of the PP sheet at the buried copper block position is compensated by 8.5mil larger than the slot size of the original copper block on one side;

[0014] Milling PP sheet: Punch out the positioning holes corresponding to the core plate position, use the two sides of the smooth plate with a thickness of more than 0.5mm to clamp the PP sheet, and use a combination of rough milling and fine milling. The cutting speed is set to 0.3m / min, the number of stacking plates is 15 sheets / stack, and the cover plate and gong cutter are replaced every time the plate is run, so that the PP sheet slot size accuracy is ≤±4mil;

[0015] Step S3, burying the copper block;

[0016] Step S4, pressing:

[0017] The order of layout is: bottom plate / kraft paper / steel plate / buffer pad / aluminum sheet / release film / PCB board / release film / aluminum sheet / buffer pad / steel plate / kraft paper / cover plate, among which the aluminum sheet is brand new and the copper block of the PCB board faces upwards;

[0018] Use the pressing plate program corresponding to the PP sheet for pressing;

[0019] Step S5, using a ceramic grinding plate to remove residual glue on the surface of the copper block;

[0020] Step S6, laser ablation, comprises:

[0021] The laser drilling belt is made by taking the original copper block slot size of 8mil on one side as the baseline and extending 5mm width area inside the copper block to ensure that the laser does not burn the edge of the copper block;

[0022] Laser drilling is used to ablate and remove residual glue on the surface of the copper block. The residual glue is ablated on both sides of the buried copper block, and the residual glue is ablated on the exposed side of the blind buried copper block. If there is still residual glue after ablation, it is polished with sandpaper of 600 mesh or above to make the residual glue width of the copper block edge ≤0.25mm; after ablation, the drop depth between the copper block and the board surface is ≤±3mil;

[0023] Step S7, drilling, includes:

[0024] The holes on the copper block are drilled independently with X-Ray target holes, 1PNL / stack, and the copper substrate is drilled with a special drill, and meets the following requirements:

[0025] The buried copper block is exposed on one side, or the stepped copper block with two sides exposed only drills the large side of the copper block. Then the exposed side is placed downward or the large side of the copper block is placed downward for drilling, that is, drilling is done from the PCB side or the small side of the copper block downward, and aluminum sheet is used for drilling;

[0026] The buried copper block is exposed on both sides. The small surface of the copper block is drilled for straight copper block or stepped copper block. There is no limit on the drilling surface. The cover plate is used for drilling.

[0027] After drilling, there is no burr on the hole, the burr height is ≤0.05mm, and there is no copper wire residue in the hole;

[0028] Use Tg+10℃ rack baking plate;

[0029] Step S8, electroplating and post-process.

[0030] Furthermore, the buried copper block is a straight copper block or a stepped copper block.

[0031] Furthermore, the minimum size of the buried copper block is 3*3 mm, and the maximum size is 30*40 mm.

[0032] Furthermore, the minimum hole diameter of the copper block is 0.5 mm, and the hole diameters of the copper blocks with different thicknesses are as follows:

[0033] The thickness of the copper block is 1.0mm, and the diameter of the drilling tool is ≥0.5mm;

[0034] The thickness of the copper block is 1.5mm, and the diameter of the drilling tool is ≥0.8mm;

[0035] The thickness of the copper block is 2.0mm, and the diameter of the drilling tool is ≥1.0mm;

[0036] The thickness of the copper block is 2.5mm, and the diameter of the drilling tool is ≥1.5mm.

[0037] Furthermore, the minimum hole wall spacing on the copper block is 0.4 mm, and the distance between the hole wall and the edge of the copper block is ≥0.5 mm.

[0038] Furthermore, the distance between adjacent copper blocks is ≥9 mm.

[0039] Compared with the prior art, the method for manufacturing a buried copper block PCB board provided by the present invention has the following beneficial effects:

[0040] The manufacturing method of the buried copper block PCB board provided by the present invention improves the accuracy of the milling slot hole by optimizing the milling core plate and the milling PP sheet process, thereby improving the matching degree between the copper block and the milling slot and reducing the width of the glue filling; when pressing, the multi-layer pads are symmetrically arranged on both sides of the PCB board as a buffer layer, which can improve the force uniformity of the PCB board during pressing, and the copper block and the board surface have high flatness after pressing, and the glue filling around the copper block is uniform; when the PCB board is drilled by laser drilling, the laser first ablates the residual glue on the surface of the copper block to further ensure the flatness of the copper block surface, and optimizes the drilling surface according to the copper buried method and the copper block type, and optimizes the drilling tool diameter according to the copper blocks of different thicknesses, reduces the burrs at the hole mouth, and improves the drilling quality. The manufacturing method of the buried copper block PCB board of the present invention improves the flatness of the copper block and the board surface and the surface quality of the copper block, and there is no stratification at the connection position between the copper block and the PCB. DETAILED DESCRIPTION

[0041] In order 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 objects, features and advantages of the present invention more obvious and understandable, the specific implementation modes of the present invention are further described below.

[0042] It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as there is no conflict between them.

[0043] A method for manufacturing a copper-buried PCB board comprises the following steps:

[0044] Step S1, making a copper block according to the size of the PCB milling groove;

[0045] The copper block is designed as a straight block or a stepped copper block according to the process requirements. The copper block used is red copper or red copper. Its side wall is perpendicular to the surface without chamfers, smooth, undamaged, and without knife marks. The edge has no defects such as notches, pits, and protrusions. Each block is individually packaged and stored with foam separations. The size and thickness meet the requirements of the drawings. The length and width tolerance is ≤±0.05mm (affecting the width of the glue filling), and the thickness tolerance is ≤±0.03mm; then it is browned using a special fixture and baked at 105℃*1h.

[0046] Specifically, the minimum size of the copper block is 3*3 mm, and the maximum size is 30*40 mm.

[0047] Step S2, corresponding to the position where the copper block is buried, the core plate and the PP sheet are milled, and the copper block is buried in a through-burying or blind-burying manner, wherein the core plate includes:

[0048] Core board gong belt design: 8mil copper is cut on one side of the inner and outer layers to prevent burrs from rolling up when milling the core board. If the slot wall where the core board slot contacts the copper block is not copper-plated, the size of the core board slot is 4.5mil larger than the original copper block slot size; if the slot wall where the core board slot contacts the copper block is copper-plated, the size of the core board slot is 4.5mil larger than the original copper block slot size (4.5mil + copper plating thickness).

[0049] Milling core board: PE-Punch punches out 5 rivet positioning holes, the thickness of the stacked board is ≤3.0mm, and a light board of the same size is laid on the core board as a cover board. A combination of rough milling and fine milling is adopted. Each slot is independently divided and compensated separately. The cutting speed of the core board close to the outer layer is set to 0.3m / min, and the cutting speed of other core boards is controlled according to the rough milling parameters. The dimensional accuracy of the core board slot is ≤±3mil, and the gap is reduced to reduce the width of the glue filling;

[0050] Milling PP sheet includes:

[0051] PP sheet gong belt design: When the copper block is buried blindly, the PP sheet in contact with the bottom of the copper block is not slotted; when the copper table is buried, the PP sheet in contact with the stepped surface of the copper block is slotted according to the size of the small copper table; the slot size of the PP sheet at the buried copper block position is compensated by 8.5mil larger than the slot size of the original copper block on one side;

[0052] Milling PP sheet: Punch out the positioning holes corresponding to the core plate position, use the two sides of the smooth plate with a thickness of more than 0.5mm to clamp the PP sheet, and use a combination of rough milling and fine milling. The cutting speed is set to 0.3m / min, the number of stacking plates is 15 sheets / stack, and the cover plate and gong cutter are replaced for each trip, so that the PP sheet slot size accuracy is ≤±4mil; after milling the PP sheet, there is no residual glue in the milling groove;

[0053] In this embodiment, the rough milling and fine milling parameters in the milling of the core plate and the milling of the PP sheet can be set according to the TG value of the substrate, as follows:

[0054]

[0055] Step S3, burying the copper block, ensuring that the copper block is level with the PCB board, flat and without tilting or warping;

[0056] Step S4, pressing:

[0057] The order of layout is: bottom plate / kraft paper / steel plate / buffer pad / aluminum sheet / release film / PCB board / release film / aluminum sheet / buffer pad / steel plate / kraft paper / cover plate; the aluminum sheet is brand new, cleaned with wax cloth, without defects such as dents and wrinkles, the copper block of the PCB board faces upward, and the pressing procedure corresponding to the PP sheet is used for pressing;

[0058] After pressing, visually check whether the glue flow is uniform, and do slice analysis to ensure that the glue filling around the copper block is full, without gaps or pinholes, and the copper block and sub-board are not offset;

[0059] Step S5, grinding the plate with a ceramic plate to remove residual glue on the surface of the copper block; when grinding the plate, the slots are facing downward to prevent it from not drying out;

[0060] Step S6, laser ablation, comprises:

[0061] The laser drilling belt is made by taking the original copper block slot size of 8mil on one side as the baseline and extending 5mm width area inside the copper block to ensure that the laser does not burn the edge of the copper block;

[0062] Laser drilling is used to ablate and remove residual glue on the surface of the copper block. The residual glue is ablated on both sides of the buried copper block, and the residual glue is ablated on the exposed side of the blind buried copper block. If there is still residual glue after ablation, it is polished with sandpaper of 600 mesh or above to make the residual glue width of the copper block edge ≤0.25mm; after ablation, the drop depth between the copper block and the board surface is ≤±3mil;

[0063] Step S7, drilling, includes:

[0064] The holes on the copper block are drilled independently with X-Ray target holes, 1PNL / stack, and the copper substrate is drilled with a special drill, and meets the following requirements:

[0065] The buried copper block is exposed on one side, or the stepped copper block with two sides exposed only drills the large side of the copper block. Then the exposed side is placed downward or the large side of the copper block is placed downward for drilling, that is, drilling is done from the PCB side or the small side of the copper block downward, and aluminum sheet is used for drilling;

[0066] The buried copper block is exposed on both sides. The small surface of the copper block is drilled for straight copper block or stepped copper block. There is no limit on the drilling surface. The cover plate is used for drilling.

[0067] After drilling, there is no burr on the hole, the burr height is ≤0.05mm, and there is no copper wire residue in the hole;

[0068] Use Tg+10℃ rack to bake the plate for 2h;

[0069] Specifically, the minimum hole diameter of the copper block is 0.5mm, and the hole diameters of the copper blocks with different thicknesses are as follows:

[0070] The thickness of the copper block is 1.0mm, and the diameter of the drilling tool is ≥0.5mm;

[0071] The thickness of the copper block is 1.5mm, and the diameter of the drilling tool is ≥0.8mm;

[0072] The thickness of the copper block is 2.0mm, and the diameter of the drilling tool is ≥1.0mm;

[0073] The thickness of the copper block is 2.5mm, and the diameter of the drilling tool is ≥1.5mm;

[0074] The minimum hole wall spacing on the copper block is 0.4mm, the distance between the hole wall and the edge of the copper block is ≥0.5mm; and the distance between adjacent copper blocks is ≥9mm.

[0075] In this embodiment, the drilling parameters corresponding to different tool diameters are as follows:

[0076]

[0077]

[0078] Step S8, electroplating and post-process.

[0079] Using the method for manufacturing a copper-buried PCB board of the present invention, the performance of the PCB board is tested as follows:

[0080]

[0081] The manufacturing method of the buried copper block PCB board provided by the present invention improves the accuracy of the milling slot hole by optimizing the milling core plate and the milling PP sheet process, thereby improving the matching degree between the copper block and the milling slot and reducing the width of the glue filling; when pressing, the multi-layer pads are symmetrically arranged on both sides of the PCB board as a buffer layer, which can improve the force uniformity of the PCB board during pressing, and the copper block and the board surface have high flatness after pressing, and the glue filling around the copper block is uniform; when the PCB board is drilled by laser drilling, the laser first ablates the residual glue on the surface of the copper block to further ensure the flatness of the copper block surface, and optimizes the drilling surface according to the copper buried method and the copper block type, and optimizes the drilling tool diameter according to the copper blocks of different thicknesses, reduces the burrs at the hole mouth, and improves the drilling quality. The manufacturing method of the buried copper block PCB board of the present invention improves the flatness of the copper block and the board surface and the surface quality of the copper block, and there is no stratification at the connection position between the copper block and the PCB.

[0082] The embodiments of the present invention are 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 are still within the protection scope of the present invention.

Claims

1. A method for manufacturing a buried copper block PCB board, characterized in that: The steps include: Step S1, making a copper block according to the size of the PCB milling groove; Step S2, corresponding to the position where the copper block is buried, the core plate and the PP sheet are milled, and the copper block is buried in a through-burying or blind-burying manner, wherein the core plate includes: Core board gong belt design: 8mil copper is cut on one side of the inner and outer layers to prevent burrs from rolling up when milling the core board. If the slot wall where the core board slot contacts the copper block is not copper-plated, the size of the core board slot is 4.5mil larger than the original copper block slot size; if the slot wall where the core board slot contacts the copper block is copper-plated, the size of the core board slot is 4.5mil larger than the original copper block slot size (4.5mil + copper plating thickness). Milling core board: Punch out positioning holes, the thickness of the stacked boards is ≤3.0mm, lay the same size of light board on the core board as the cover board, adopt the combination of rough milling and fine milling, each slot is independently divided and compensated separately, the cutting speed of the core board close to the outer layer is set to 0.3m / min, and the cutting speed of other core boards is controlled according to the rough milling parameters, so that the core board slot size accuracy is ≤±3mil; Milling PP sheet includes: PP sheet gong belt design: When the copper block is buried blindly, the PP sheet in contact with the bottom of the copper block is not slotted; when the copper table is buried, the PP sheet in contact with the stepped surface of the copper block is slotted according to the size of the small copper table; the slot size of the PP sheet at the buried copper block position is compensated by 8.5mil larger than the slot size of the original copper block on one side; Milling PP sheet: Punch out the positioning holes corresponding to the core plate position, use the two sides of the smooth plate with a thickness of more than 0.5mm to clamp the PP sheet, and use a combination of rough milling and fine milling. The cutting speed is set to 0.3m / min, the number of stacking plates is 15 sheets / stack, and the cover plate and gong cutter are replaced every time the plate is run, so that the PP sheet slot size accuracy is ≤±4mil; Step S3, burying the copper block; Step S4, pressing: The order of layout is: bottom plate / kraft paper / steel plate / buffer pad / aluminum sheet / release film / PCB board / release film / aluminum sheet / buffer pad / steel plate / kraft paper / cover plate, among which the aluminum sheet is brand new and the copper block of the PCB board faces upwards; Use the pressing plate program corresponding to the PP sheet for pressing; Step S5, using a ceramic grinding plate to remove residual glue on the surface of the copper block; Step S6, laser ablation, comprises: The laser drilling belt is made by taking the original copper block slot size of 8mil on one side as the baseline and extending 5mm width area inside the copper block to ensure that the laser does not burn the edge of the copper block; Laser drilling is used to ablate and remove residual glue on the surface of the copper block. The residual glue is ablated on both sides of the buried copper block, and the residual glue is ablated on the exposed side of the blind buried copper block. If there is still residual glue after ablation, it is polished with sandpaper of 600 mesh or above to make the residual glue width of the copper block edge ≤0.25mm; after ablation, the drop depth between the copper block and the board surface is ≤±3mil; Step S7, drilling, includes: The holes on the copper block are drilled independently with X-Ray target holes, 1PNL / stack, and the copper substrate is drilled with a special drill, and meets the following requirements: The buried copper block is exposed on one side, or the stepped copper block with two sides exposed only drills the large side of the copper block. Then the exposed side is placed downward or the large side of the copper block is placed downward for drilling, that is, drilling is done from the PCB side or the small side of the copper block downward, and aluminum sheet is used for drilling; The buried copper block is exposed on both sides. The small surface of the copper block is drilled for straight copper block or stepped copper block. There is no limit on the drilling surface. The cover plate is used for drilling. After drilling, there is no burr on the hole, the burr height is ≤0.05mm, and there is no copper wire residue in the hole; Use Tg+10℃ rack baking plate; Step S8, electroplating and post-process.

2. The method for manufacturing a buried copper block PCB according to claim 1, characterized in that: The buried copper block is a straight copper block or a stepped copper block.

3. The method for manufacturing a buried copper block PCB according to claim 2, characterized in that: The minimum size of the buried copper block is 3*3mm and the maximum size is 30*40mm.

4. The method for manufacturing a buried copper block PCB according to claim 1, characterized in that: The minimum hole diameter for drilling on copper blocks is 0.5mm, and the hole diameters for drilling on copper blocks of different thicknesses are as follows: The thickness of the copper block is 1.0mm, and the diameter of the drilling tool is ≥0.5mm; The thickness of the copper block is 1.5mm, and the diameter of the drilling tool is ≥0.8mm; The thickness of the copper block is 2.0mm, and the diameter of the drilling tool is ≥1.0mm; The thickness of the copper block is 2.5mm, and the diameter of the drilling tool is ≥1.5mm.

5. The method for manufacturing a buried copper block PCB according to claim 4, characterized in that: The minimum hole wall spacing on the copper block is 0.4mm, and the distance between the hole wall and the edge of the copper block is ≥0.5mm.

6. The method for manufacturing a buried copper block PCB according to claim 1, characterized in that: The distance between adjacent copper blocks is ≥9mm.

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