A PCB manufacturing method for preventing slot copper layer from delamination and a PCB

Abstract

The present invention belongs to the technical field of PCB board manufacturing, and discloses a PCB board manufacturing method for preventing slot hole copper layer delamination and a PCB board, and the PCB board manufacturing method for preventing slot hole copper layer delamination comprises the following steps: after drilling a slot hole on the PCB board, the first baking plate, copper deposition, full-board electroplating and second baking plate are sequentially performed, wherein the baking plate temperature of the first baking plate and the second baking plate are both 145-155°C, and the baking plate time is both 4-5h; the copper layer thickness of the PTH slot hole wall after full-board electroplating is ≥12μm. The present invention can effectively reduce the stress of the slot hole by controlling the copper layer thickness of the PTH slot hole wall after full-board electroplating to 12μm, and then cooperates with the baking plate temperature and baking plate time control of the first baking plate and the second baking plate, and the three processes are combined to produce a synergistic effect, effectively improve the adhesion between the slot hole and the copper layer, prevent the copper layer from separating during the tin spraying process, and greatly reduce the probability of copper layer separation in the slot hole of the PCB board.

Description

Technical Field

[0001] The invention relates to the technical field of PCB board manufacturing, and in particular to a PCB board manufacturing method for preventing slot hole copper layer delamination and a PCB board. Background Art

[0002] With the rapid development and widespread application of integrated circuits, the size of electronic equipment has become smaller and smaller, and the density and difficulty of circuit wiring have become increasingly greater, which requires printed circuit boards to be constantly updated; currently, the varieties of PCB boards have developed from single-sided boards to double-sided boards, multi-layer boards and flexible boards.

[0003] The use of tin spraying technology for surface treatment of PCB boards is currently a common production process choice. However, in the actual production process of PCB boards, the copper layer separation problem of PTH slots will easily occur during the tin spraying process of PCB boards. Once the copper layer separation occurs, it will bury reliability risks for the downstream of the PCB board. If reliability problems occur in the downstream customers or terminals of the PCB board due to this defect, it will have an adverse impact on the PCB board manufacturer and be accompanied by huge claims. Therefore, the copper layer separation problem of PTH slots has always plagued PCB board manufacturers and related suppliers and has received much attention.

[0004] At present, there is a common phenomenon of copper layer separation during the tin spraying process of PCB boards with PTH slots. There are not many effective improvement measures for double-sided PCB boards, while multi-layer PCB boards mainly design copper rings on the inner layer at the PTH slot position. After copper deposition and full-board electroplating, the copper layer on the hole wall of the PTH slot is connected to the copper ring on the inner layer, thereby enhancing the adhesion of the copper layer on the hole wall and preventing the copper layer on the hole wall from delaminating during tin spraying.

[0005] Although the above method effectively prevents the copper layer from separating from the hole wall of the PCB board during tin spraying, this method changes the customer's design and is likely to have other adverse effects on the production of downstream customers. It requires the customer's consent in advance before use.

[0006] There are other methods such as baking the board before tinning and then hot plate tinning, which will improve the separation of the copper layer on the hole wall of the PTH slot, but it cannot completely solve the problem. Most of them can only reduce the severity of the delamination.

[0007] In addition, due to the excessive stress on the edge of the slot hole of the PCB substrate after the copper layer of the slot hole is separated during the tin spraying process, the PCB board will have edge bursting problems.

[0008] Chinese patent 201720105972.6 discloses a circuit board with a heat dissipation and explosion-proof edge structure, wherein the circuit board is provided with slots, and the circuit board is provided with a plurality of heat dissipation reinforcement holes distributed around the periphery of the slots. Through the plurality of heat dissipation reinforcement holes around the slots, the force on the slots of the circuit board can be enhanced, and the contact stress on the edges of the slots can be reduced; secondly, the heat dissipation capacity of the circuit board can be enhanced, and the explosion-proof edge problem during the lead-free tin spraying process can be effectively prevented, thereby reducing the scrap rate of the slot explosion and improving the yield rate of the lead-free tin spraying.

[0009] The above patented technology reduces the stress of the slot hole by distributing several heat dissipation reinforcement holes around the slot hole, thereby preventing edge bursting. However, it also changes the customer's design and is likely to bring other adverse effects to the production of downstream customers. Therefore, the customer's consent must be obtained in advance before use.

[0010] Therefore, it is necessary to develop a PCB manufacturing method that can prevent the slot copper layer from delamination, so as to effectively prevent the slot copper layer from delamination without changing the customer's PCB board route design, thereby further preventing the PCB board slot from bursting. Summary of the invention

[0011] One of the purposes of the present invention is to provide a PCB manufacturing method for preventing slot copper layer delamination, so as to solve the technical problem that the prior art cannot effectively prevent slot copper layer delamination without changing the customer design, and further causes PCB slot edge bursting.

[0012] Another object of the present invention is to provide a PCB board, which is manufactured by the above-mentioned PCB board manufacturing method for preventing slot hole copper layer delamination, effectively preventing the separation of the PCB board slot hole copper layer and improving product quality and yield rate.

[0013] To achieve the above object, the present invention provides a PCB manufacturing method for preventing slot hole copper layer delamination, comprising the following steps: after drilling the slot hole on the PCB board, first baking the board, copper deposition, full board electroplating and second baking the board are sequentially performed;

[0014] The baking temperatures of the first baking and the second baking are both 145-155°C, and the baking time is 4-5h; the copper layer thickness of the PTH slot wall after full-board electroplating is ≥12μm.

[0015] Preferably, the production method comprises the following steps:

[0016] Step 1: Cutting; Step 2: Inner layer; Step 3: Lamination; Step 4: Drilling; Step 5: Drilling gong slot holes; Step 6: First baking; Step 7: Copper deposition; Step 8: Full board plating; Step 9: Outer layer graphics; Step 10: Graphic plating; Step 11: Outer layer etching; Step 12: Outer layer AOI inspection; Step 13: Solder mask; Step 14: Characters; Step 15: Second baking; Step 16: Spray tin; Step 17: Molding; Step 18: Testing; Step 19: FQC; Step 20: Packaging.

[0017] Furthermore, the production method comprises the following specific steps:

[0018] Step 1: Cut the copper clad laminate into suitable sizes for production;

[0019] Step 2: Inner layer, make the circuit pattern on the inner core board;

[0020] Step 3: Lamination: Lamination the inner core board, PP and copper foil together at high temperature to form a PCB board;

[0021] Step 4: Drilling: Drill the required holes in the PCB board;

[0022] Step 5: Drill or punch out the PTH slot in the PCB board;

[0023] Step 6: Bake the PCB for the first time at 145-155°C for 4-5 hours;

[0024] Step 7: Copper deposition, electroplating a layer of copper in the holes of the PCB board and the PTH slots to metallize the hole walls of the drilled holes and PTH slots;

[0025] Step 8: Full board electroplating, thickening the copper layer thickness of the PCB board holes and PTH slots to ≥12μm;

[0026] Step 9: Outer layer graphics, make circuit graphics on PCB board through graphics transfer;

[0027] Step 10: Graphic electroplating, thickening the copper layer thickness of the PCB board holes and PTH slots to the customer's required value;

[0028] Step 11: Etch the outer layer to remove the unnecessary copper layer and leave the required circuit pattern;

[0029] Step 12: Outer layer AOI inspection to check whether the PCB circuit has defects;

[0030] Step 13: Solder mask, cover the surface of the PCB with a layer of insulating ink to protect the copper layer of the circuit;

[0031] Step 14: Print the characters of components on the surface of the PCB board;

[0032] Step 15: Bake the PCB board for the second time at 145-155℃ for 4-5h;

[0033] Step 16: Spray tin to cover the copper surface with a tin layer with good solderability;

[0034] Step 17: Molding, forming or beating the PCB into the size and shape required by the customer;

[0035] Step 18: Test, open circuit and short circuit test of PCB board;

[0036] Step 19: FQC, check whether the PCB board meets the requirements;

[0037] Step 20: Packaging: vacuum pack the PCB to prevent moisture.

[0038] Preferably, the thickness of the copper layer after pattern electroplating in step 10 is 25 μm.

[0039] Preferably, the tin spraying in step 16 is lead tin spraying or lead-free tin spraying.

[0040] At the same time, the present invention also provides a PCB board, which is manufactured by using the above-mentioned PCB board manufacturing method for preventing slot hole copper layer delamination.

[0041] Beneficial Effects

[0042] Compared with the prior art, the present invention has at least the following advantages:

[0043] (1) The present invention is critical to controlling the thickness of the copper layer on the PTH slot hole wall after full-board electroplating. Compared with the PTH slot hole copper layer thickness of 5 μm and 8 μm commonly used in the prior art, the slot hole stress of the PCB board is reduced, and dark cracks and cracks will not occur during the subsequent process. The internal stress of the slot hole of the PCB board is reduced, and the adhesion between the slot hole and the copper layer is improved in combination with the baking process;

[0044] (2) The present invention effectively dries the moisture of the PCB board during the first baking process, preventing the PCB board from warping, making the thickness control of the PTH slot copper layer more accurate during the subsequent full-board electroplating process, and the reduction of the moisture of the PCB board can effectively improve the adhesion between the slot and the copper layer, effectively reducing the probability of separation between the slot and the copper layer;

[0045] (3) The present invention fully preheats the PCB board by long-term baking during the second baking, so that the inside of the PCB board substrate covered by the copper layer is also fully preheated, effectively avoiding the occurrence of board explosion or slot edge explosion during the tin spraying process;

[0046] (4) The present invention provides a PCB manufacturing method for preventing the delamination of the copper layer of the slot hole. By controlling the copper layer thickness of the PTH slot hole wall to 12 μm after the entire board is electroplated, the stress of the slot hole can be effectively reduced. Combined with the baking plate temperature and baking plate time control of the first baking plate and the second baking plate, the three steps are combined to produce a synergistic effect, which effectively improves the adhesion between the slot hole and the copper layer, prevents the copper layer from separating during the tin spraying process, and greatly reduces the probability of copper layer separation in the slot hole of the PCB board. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention is further described below in conjunction with the accompanying drawings, embodiments and comparative examples;

[0048] Figure 1 This is a 400x microscope magnification of the finished PCB board;

[0049] Figure 2 This is a 400x microscope magnification of the copper layer separation in the slot of the PCB board;

[0050] Figure 3 This is a photo of the copper layer of the PCB board separated by the slot. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0052] In order to explain the technical content of the present invention in detail, further description is given below in conjunction with the implementation modes.

[0053] Example 1

[0054] A PCB board is prepared by the following steps:

[0055] Step 1: Cut the copper clad laminate into suitable sizes for production;

[0056] Step 2: Inner layer, make the circuit pattern on the inner core board;

[0057] Step 3: Lamination: Lamination the inner core board, PP and copper foil together at high temperature to form a PCB board;

[0058] Step 4: Drilling: Drill the required holes in the PCB board;

[0059] Step 5: Drill or punch out the PTH slot in the PCB board;

[0060] Step 6: First baking sheet;

[0061] Step 7: Copper deposition, electroplating a layer of copper in the holes of the PCB board and the PTH slots to metallize the hole walls of the drilled holes and PTH slots;

[0062] Step 8: Full board electroplating, thickening the copper layer thickness of the PCB board holes and PTH slots to 12μm;

[0063] Step 9: Outer layer graphics, make circuit graphics on PCB board through graphics transfer;

[0064] Step 10: Graphic electroplating, thickening the copper layer thickness of the PCB board holes and PTH slots to 25μm;

[0065] Step 11: Etch the outer layer to remove the unnecessary copper layer and leave the required circuit pattern;

[0066] Step 12: Outer layer AOI inspection to check whether the PCB circuit has defects;

[0067] Step 13: Solder mask, cover the surface of the PCB with a layer of insulating ink to protect the copper layer of the circuit;

[0068] Step 14: Print the characters of components on the surface of the PCB board;

[0069] Step 15: Bake the sheet for the second time;

[0070] Step 16: Spray tin to cover the copper surface with a tin layer with good solderability;

[0071] Step 17: Molding, forming or beating the PCB into the size and shape required by the customer;

[0072] Step 18: Test, open circuit and short circuit test of PCB board;

[0073] Step 19: FQC, check whether the PCB board meets the requirements;

[0074] Step 20: Packaging: vacuum pack the PCB to prevent moisture;

[0075] The baking temperatures of the first and second baking plates were both 145° C., and the baking time was 5 h. The copper layer thickness of the PTH slot wall after full-plate electroplating was 12 μm.

[0076] Example 2

[0077] It is generally the same as Example 1, except that the baking plate temperature of the first baking plate and the second baking plate is 155° C., and the baking plate time is 4 hours;

[0078] Example 3

[0079] The method is substantially the same as Example 1, except that the first baking temperature is 150° C. and the baking time is 4.5 h, and the second baking temperature is 145° C. and the baking time is 4.5 h.

[0080] Example 4

[0081] It is generally the same as Example 1, except that the baking plate temperature of the first baking plate is 152° C. and the baking plate time is 4.2 h, and the baking plate temperature of the second baking plate is 148° C. and the baking plate time is 4.2 h.

[0082] Example 5

[0083] The embodiment is substantially the same as the embodiment 1, except that the copper layer thickness of the PTH slot hole wall after full-board electroplating is 14 μm.

[0084] Comparative Example 1

[0085] The same as Example 1, except that the copper layer thickness of the PTH slot wall after full-board electroplating is 5 μm;

[0086] It is generally the same as Example 1, except that the copper layer thickness of the PTH slot wall after full-board electroplating is 8 μm;

[0087] Comparative Example 3

[0088] It is generally the same as Example 1, except that the baking plate temperature of the first baking plate is 140°C.

[0089] Comparative Example 4

[0090] It is generally the same as Example 1, except that the baking plate temperature of the first baking plate is 160°C.

[0091] Comparative Example 5

[0092] It is generally the same as Example 1, except that the baking time of the first baking plate is 3.5 hours.

[0093] Comparative Example 6

[0094] It is generally the same as Example 1, except that the baking plate temperature of the second baking plate is 140°C.

[0095] Comparative Example 7

[0096] It is generally the same as Example 1, except that the baking plate temperature of the second baking plate is 160°C.

[0097] Comparative Example 8

[0098] It is generally the same as Example 1, except that the baking time of the second baking plate is 3.5 hours.

[0099] Comparative Example 9

[0100] It is generally the same as Example 1, except that the first baking plate in step 6 is omitted.

[0101] Comparative Example 10

[0102] The method is substantially the same as Example 1, except that the second baking of the plate in step 15 is omitted.

[0103] Results Test

[0104] 10,000 PCB boards of Examples 1-4 and Comparative Examples 1-11 were prepared, and the number of copper layer separations that occurred during the tin spraying process was counted to obtain the yield rate. The results are shown in Table 1.

[0105] Figure 1 This is a 400x microscope magnification of the finished PCB board; Figure 2 This is a 400x microscope magnification of the copper layer separation in the slot of the PCB board.

[0106] Among them, the yield rate = (10000-number of copper layer separations) / 10000*100%;

[0107] Among them, in Comparative Examples 4 and 7, the PCB boards were burned out and became scrap due to the overly high baking plate temperature and long baking time, and the scrap rate was over 70%. Therefore, the number of copper layer separation boards and the yield rate were no longer counted.

[0108] Table 1 Number of copper layer separation plates and yield rate results per 10,000 pieces of Examples 1-4 and Comparative Examples 1-11

[0109] Number of copper layer separation boards Yield Example 1 6 99.94％ Example 2 5 99.95％ Example 3 6 99.94％ Example 4 3 99.97％ Example 5 5 99.95％ Comparative Example 1 1387 86.13％ Comparative Example 2 1403 85.97％ Comparative Example 3 782 92.18％ Comparative Example 4 / / Comparative Example 5 908 91.92％ Comparative Example 6 599 94.01％ Comparative Example 7 / / Comparative Example 8 923 91.77％ Comparative Example 10 1787 82.13％ Comparative Example 11 1508 84.92％

[0110] According to the results in Table 1, we can see that:

[0111] According to the comparison of the results of Example 1 with Comparative Examples 1 and 2, the present invention can effectively reduce the frequency of separation of the slot copper layer of the PCB board during the tin spraying process by controlling the thickness of the copper layer on the PTH slot hole wall after the whole board is electroplated. The reason is that the PTH slot hole copper layer thickness of 12 μm can greatly reduce the slot hole stress of the PCB board, and the thickness will not reduce the temperature transfer efficiency of the second baking plate, so that the inside of the PCB board substrate covered by the copper layer is also fully preheated, and the slot hole will not be separated from the copper layer due to the temperature difference and excessive slot hole stress during the tin spraying process.

[0112] According to the comparison of the results of Example 1 with Comparative Examples 3 and 5, it can be seen that the first baking after drilling the PTH slots on the PCB board can alleviate the situation of slot copper layer separation during the tin spraying process of the PCB board. The reason is that the first baking process can effectively dry the moisture of the PCB board and improve the adhesion between the slots and the copper layer. However, too low baking temperature and too short baking time cannot well solve the problem of slot copper layer separation during the tin spraying process of the PCB board. The present invention controls the baking temperature and baking time of the first baking, and combines the PTH slot copper layer thickness of 12μm and the second baking, so as to produce a synergistic effect, greatly improve the yield of the PCB board, and reduce the frequency of slot copper layer separation during the tin spraying process of the PCB board.

[0113] It should be noted that if the baking time of the first baking plate is too long and exceeds the scope of the technical solution of the present invention, it will not have much impact on the frequency of copper layer separation of the PCB board, but it will lead to increased production time and energy consumption during mass production, thereby increasing production costs.

[0114] According to the comparison of the results of Example 1 with Comparative Examples 6 and 8, it can be seen that the second baking after drilling the PTH slots on the PCB can alleviate the problem of the copper layer separation of the slots during the tin spraying process of the PCB. The reason is that the second baking process can effectively avoid the situation that the temperature difference between the PCB and the tin spraying process is too large, which leads to the cracking of the PCB slots. The cracking of the PCB slots will also cause the separation of the copper layer of the slots. Therefore, after the second baking, the separation of the copper layer of the PCB slots will be alleviated. However, too low baking temperature and too short baking time cannot solve the problem of the separation of the copper layer of the slots during the tin spraying process of the PCB. The present invention controls the baking temperature and baking time of the second baking to achieve the desired effect. The 12μm thickness of the PTH slot copper layer and the second baking plate produce a synergistic effect, which greatly improves the yield rate of PCB boards and reduces the frequency of slot copper layer separation during the tin spraying process of PCB boards. The reason may be that after the first baking plate, the baking plate temperature and baking plate time are strictly controlled to reduce the moisture of the PCB board and improve the adhesion between the subsequent copper layer and the slot hole. The slot hole stress is effectively reduced by controlling the thickness of the PTH slot hole copper layer. The 12μm slot hole copper layer thickness combined with the baking plate time and baking plate temperature control of the second baking plate can fully preheat the inside of the PCB board substrate covered by the copper layer, effectively avoiding the separation of the copper layer and the slot hole caused by insufficient release of the internal stress of the PCB board and excessive temperature difference of tin spraying.

[0115] According to the comparison of the results of Example 1 with Comparative Examples 9 and 10, it can be seen that in the technical solution of the present invention, the first baking plate and the second baking plate are indispensable. The first baking plate, the control of the thickness of the PTH slot copper layer and the second baking plate are required to effectively prevent the slot copper layer of the PCB board from being delaminated during the tin spraying process.

[0116] According to the comparison of the results of Example 1 and Example 5, when the thickness of the PTH slot copper layer is ≥12μm, the delamination of the slot copper layer of the PCB board during the tin spraying process has been controlled, but when the thickness of the PTH slot copper layer is greater than 12μm, its production cost will be greatly increased, because the plating area of ​​the whole board in step 8 is much larger than that of the pattern plating in step 10, so the copper consumption will also be greatly increased.

[0117] The embodiments presented herein are only embodiments selected according to the combination of all possible embodiments. The appended claims should not be limited by the embodiments describing the present invention. Some numerical ranges used in the claims include sub-ranges therein, and the changes in these ranges should also be covered by the appended claims.

Claims

1. A method for manufacturing a PCB board to prevent slot copper layer delamination, characterized in that: The production method comprises the following steps: Step 1: Cutting; Step 2: Inner layer; Step 3: Lamination; Step 4: Drilling; Step 5: Drilling slot holes; Step 6: First baking; Step 7: Copper deposition; Step 8: Full board plating; Step 9: Outer layer graphics; Step 10: Graphics plating; Step 11: Outer layer etching; Step 12: Outer layer AOI inspection; Step 13: Solder mask; Step 14: Characters; Step 15: Second baking; Step 16: Spray tin; Step 17: Molding; Step 18: Testing; Step 19: FQC; Step 20: Packaging; The baking temperatures of the first baking and the second baking were both 145-155°C, and the baking time was 4-5h. The copper layer thickness of the PTH slot wall after the whole board was electroplated was 12μm.

2. The method for manufacturing a PCB board for preventing slot copper layer delamination according to claim 1, characterized in that: The production method comprises the following specific steps: Step 1: Cut the copper clad laminate into suitable sizes for production; Step 2: Inner layer, make the circuit pattern on the inner core board; Step 3: Lamination: Lamination the inner core board, PP and copper foil together at high temperature to form a PCB board; Step 4: Drilling: Drill the required holes in the PCB board; Step 5: Drill or punch out the PTH slot in the PCB board; Step 6: Bake the PCB for the first time at 145-155°C for 4-5 hours; Step 7: Copper deposition, electroplating a layer of copper in the holes of the PCB board and the PTH slots to metallize the hole walls of the drilled holes and PTH slots; Step 8: Full board electroplating, thickening the copper layer thickness of the PCB board holes and PTH slots to 12μm; Step 9: Outer layer graphics, make circuit graphics on PCB board through graphics transfer; Step 10: Graphic electroplating, thickening the copper layer thickness of the PCB board holes and PTH slots to the customer's required value; Step 11: Etch the outer layer to remove the unnecessary copper layer and leave the required circuit pattern; Step 12: Outer layer AOI inspection to check whether the PCB circuit has defects; Step 13: Solder mask, cover the surface of the PCB with a layer of insulating ink to protect the copper layer of the circuit; Step 14: Print the characters of components on the surface of the PCB board; Step 15: Bake the PCB board for the second time at 145-155℃ for 4-5h; Step 16: Spray tin to cover the copper surface with a tin layer with good solderability; Step 17: Molding, forming or beating the PCB into the size and shape required by the customer; Step 18: Test, open circuit and short circuit test of PCB board; Step 19: FQC, check whether the PCB board meets the requirements; Step 20: Packaging: vacuum pack the PCB board to prevent moisture.

3. The method for manufacturing a PCB board for preventing slot copper layer delamination according to claim 1 or 2, characterized in that: The thickness of the copper layer after the pattern electroplating in step 10 is 25 μm.

4. The method for manufacturing a PCB board for preventing slot copper layer delamination according to claim 2, characterized in that: The tin spraying in step 16 is lead tin spraying or lead-free tin spraying.

5. A PCB board, characterized in that: The PCB is manufactured by the method for manufacturing a PCB board for preventing delamination of a slot copper layer as described in any one of claims 1 to 4.

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