A method for manufacturing a PCB board with a small hole chain resistance change rate

Abstract

The present invention discloses a method for manufacturing a PCB board with a small change rate of resistance of a hole chain, which comprises the following steps in sequence: cutting all substrates; making inner layer graphics, determining that the substrate involved in the buried hole is the Lm-Ln layer, laminating for the first time, placing PP sheets between each layer of boards, laminating after the Lm-Ln layer board and the PP sheet are stacked; drilling for the first time to form a through hole, and then performing board electricity, resin plugging, cover hole electroplating and / or cap electroplating; baking after cutting, drilling, board electricity and resin plugging; adding a substrate above the Lm layer board and below the Ln layer board, as the Lm-1 layer board and the Ln+1 layer board respectively; making the outer layer graphics for the first time: making graphics for the added substrate, and performing the second lamination, the second drilling, the second laser and the second electroplating in sequence; and so on until all boards are pressed; making the outer layer graphics and the post-process. The present invention can avoid the problem of hole copper fracture, ensure the quality of the PCB board, and the resistance change rate of the hole chain is small.

Description

Technical Field

[0001] The present invention relates to the field of PCB boards, and in particular to a method for manufacturing a PCB board with a small hole chain resistance change rate. Background Art

[0002] The circuit network of a multi-layer PCB is composed of metal lines, pads, and various holes connecting each layer. The holes in the PCB include through holes, buried holes, and blind holes. The interconnection of PCBs is achieved by the holes in the PCB, including through holes, buried holes, and blind holes. Due to the different physical properties of the substrate material and the interconnection hole plating after heating, when heated, the thermal expansion of the insulating substrate material in the Z direction forces the interconnection hole plating to deform, thereby generating stress on the interconnection hole. Plating defects such as thin interconnection hole plating thickness, bubbles in the plating, uneven plating thickness, rough hole wall and plating are the main reasons for the reliability of the hole itself; when drilling stains, resist residues and precipitation and other foreign matter remain on the interconnection surface between the interconnection hole and the inner and outer layer circuits, or when the chemical copper layer on the interconnection surface is defective, the hole plating is separated from the inner and outer layer circuits under the stress generated by thermal expansion and contraction, thereby causing problems with interconnection reliability.

[0003] Customers have higher and higher requirements for the adaptability of PCB board environment, and the quality requirements and production process requirements are more difficult. It is difficult to produce using traditional production and control methods. Conventional methods produce PCB boards and perform reflow soldering and hot and cold shock tests to ensure the quality of PCB boards.

[0004] The function of reflow soldering is to put the circuit board with SMT components installed into the SMT reflow soldering chamber, and then melt the solder paste used to solder the SMT components through high-temperature hot air to form a reflow temperature change process, so that the SMT components can be combined with the pads on the circuit board, and then cooled together. The hot and cold shock test, also known as the temperature shock test or the high and low temperature shock test, is used to assess the adaptability of the product to the rapid changes in the ambient temperature. It is an identification test for equipment design finalization and an indispensable test in the routine test of the batch production stage. In some cases, it can also be used for environmental stress screening tests. In fact, the hot and cold shock test chamber is frequently used to verify and improve the environmental adaptability of equipment.

[0005] Conventional production methods for making chain hole test boards can easily cause quality abnormalities such as cracking of the copper layer in the buried holes, delamination of the copper layer in the covered holes and the blind holes. The hole chain resistance value variation rate of the PCB board obtained by conventional production methods is large, and it is difficult to achieve a chain hole resistance value variation rate of less than 5%. Summary of the invention

[0006] In order to solve the problem that the hole chain resistance change rate of the PCB board prepared by the existing method is large, the present invention provides a PCB board manufacturing method with a small hole chain resistance change rate.

[0007] A method for manufacturing a PCB board with a small hole chain resistance change rate comprises the following steps in sequence:

[0008] Cut all substrates;

[0009] Make the inner layer pattern and determine that the substrate involved in the buried hole is the Lm-Ln layer. For the first lamination, place PP sheets between each layer of the board, and laminate the Lm-Ln layer and the PP sheet. If the PCB board is designed with more than one buried hole, select any buried hole to determine the Lm-Ln layer.

[0010] The first drilling forms a through hole, followed by board plating, resin plugging, cover hole plating and / or cap plating;

[0011] After the cutting, drilling, board bonding and resin plugging, baking is performed;

[0012] A substrate is added above the Lm layer and below the Ln layer, respectively serving as the Lm-1 layer and the Ln+1 layer; the first outer layer patterning: the patterning is performed on the added substrate, and then the second lamination, the second drilling, the second laser and the second electroplating are performed in sequence; a substrate is added above the Lm-1 layer and below the Ln+1 layer, respectively serving as the Lm-2 layer and the Ln+2 layer; the second outer layer patterning is performed: the patterning is performed on the added substrate, and then the third lamination, the third drilling, the third laser and the third electroplating are performed in sequence; and so on until all the boards are pressed;

[0013] Then, the outer layer pattern is produced and the post-process is performed to prepare the PCB board. The PCB board produced by the method can avoid the problem of hole copper fracture, has good quality, good adaptability to the environment, and is conducive to improving the life and market competitiveness of the PCB board.

[0014] Preferably, the post-process includes solder masking, molding, testing and packaging of the PCB board to ensure the quality of the PCB board.

[0015] Preferably, the post-process includes testing the PCB board, including reflow soldering and hot and cold shock experiments, and baking the board before reflow soldering, with the baking temperature being 120-140°C and the baking time being 5-7 hours. Baking the board before reflow soldering can avoid the problems of the vias between the layers of the PCB board being pulled apart, the layers being separated, and bubbles or explosions on the PCB board.

[0016] Preferably, after cutting, before making the inner layer pattern, all substrates are first baked, the first baking temperature is 170-190°C, and the first baking time is 3-5 hours. The first baking can avoid the problem of hole copper fracture caused by deformation and warping of the substrate.

[0017] Preferably, after the first drilling and before the board is electrically bonded, the multilayer board after the first lamination is baked for a second time, the second baking temperature is 140-160°C, and the second baking time is 1-3 hours. The second baking can avoid the problem of hole copper fracture caused by the internal stress of the multilayer board after lamination.

[0018] Preferably, the board is baked for the third time after being electrified and before being plugged with resin, the temperature of the third baking is 140-160°C, and the third baking time is 1-3 hours. The third baking avoids the problem of copper fracture in the hole caused by thermal expansion and contraction of the board.

[0019] Preferably, after the resin plugging, the fourth baking is performed before the cover hole electroplating and / or cap electroplating, the temperature of the fourth baking is 110-150°C, and the fourth baking time is 30-60 minutes. The fourth baking avoids the problem of delamination between electroplated layers due to thermal expansion and contraction of the resin ink.

[0020] Preferably, the resin ink used for the resin plugging is PHP-900IR-10FH ink produced by Shanrong Daily Chemicals Co., Ltd. The ink has a small expansion ratio and can avoid the copper hole from breaking.

[0021] Preferably, the minimum thickness of the cover hole electroplating is 25 μm.

[0022] Preferably, the minimum thickness of the cap electroplating is 25 μm, which can better fix the ink of the resin plugging hole.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention provides a PCB board manufacturing method with a small hole chain resistance change rate, baking is performed after cutting, drilling, board electricity and resin plugging, and multiple pressings are performed respectively, which can avoid the problem of hole copper breakage and ensure the quality of the PCB board; the manufactured PCB board, after reflow soldering and hot and cold shock test tests, has a small hole chain resistance change rate and high environmental adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the structure of a PCB board manufactured by the method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to explain the technical solution of the present invention in detail, the technical solution of the embodiment of the present invention will be clearly and completely described below. In order to explain the technical solution of the present invention in detail, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0026] The following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] A method for manufacturing a PCB board with a small hole chain resistance change rate comprises the following steps in sequence:

[0028] S1: Cut all substrates. The substrate can be EM-355(D) substrate produced by Taiguang.

[0029] S2: Make the inner layer pattern, determine that the substrate involved in the buried hole is the Lm-Ln layer, and press for the first time. Place PP sheets between each layer of the board, and press after stacking the Lm-Ln layer and the PP sheet.

[0030] S3: The first drilling forms a through hole, followed by board electroplating, resin plugging, cover hole plating and / or cap plating.

[0031] Baking is performed after cutting, drilling, board bonding and resin plugging.

[0032] S4: Add a substrate above the Lm layer and below the Ln layer, which are used as the Lm-1 layer and Ln+1 layer respectively; first outer layer patterning: patterning is performed on the added substrate, and then the second lamination, the second drilling, the second laser and the second electroplating are performed in sequence; add a substrate above the Lm-1 layer and below the Ln+1 layer, which are used as the Lm-2 layer and Ln+2 layer respectively; second outer layer patterning: patterning is performed on the added substrate, and then the third lamination, the third drilling, the third laser and the third electroplating are performed in sequence.

[0033] This process is repeated in this way until all boards are pressed together. If there are still substrates that need to be pressed together, add another substrate above the Lm-2 layer board and below the Ln+2 layer board, as the Lm-3 layer board and the Ln+3 layer board respectively. The third outer layer patterning: patterning is performed on the added substrates, and then the fourth pressing, fourth drilling, fourth laser and fourth electroplating are performed in sequence.

[0034] S5: Then, outer layer graphics production and post-processing are performed to prepare a PCB board.

[0035] Reference Figure 1 , taking a 12-layer PCB board as an example, the specific steps are as follows:

[0036] S1: Cut all substrates.

[0037] S2: Make the inner layer pattern, determine that the substrate involved in the buried hole is L4-L9 layer, and press for the first time. Place PP sheets between each layer of the board, and press after stacking the L4-L9 layer board and the PP sheet.

[0038] S3: The first drilling forms a through hole, followed by board electroplating, resin plugging, cover hole plating and / or cap plating.

[0039] Baking is performed after cutting, drilling, board bonding and resin plugging.

[0040] S4: Add a substrate above the L4 layer and below the L9 layer, which serve as the L3 layer and L10 layer respectively; the first outer layer pattern production: pattern the added substrate, and then perform the second lamination, the second drilling, the second laser and the second electroplating in sequence. The second lamination stacks the L3 layer, the PP sheet, the L4-L9 layer, the PP sheet and the L10 layer after lamination in the previous step, and then presses them, completing the lamination of the L3-L10 layer. The second drilling and the second laser drill holes through the L3-L4 layer and the L9-L10 layer.

[0041] Add a substrate above the L3 layer and below the L10 layer, which serve as the L2 layer and L11 layer respectively; Second outer layer pattern production: Pattern the added substrate, then perform the third lamination, the third drilling, the third laser and the third electroplating in sequence. The third lamination is to press the L2 layer, the PP sheet, the L3-L10 layer pressed in the previous step, the PP sheet and the L11 layer, thus completing the lamination of the L2-L11 layer. The third drilling and the third laser drilling are performed to drill holes through the L2-L3 and L10-L11 layers.

[0042] Add a substrate above the L2 layer and below the L11 layer, as the L1 layer and L12 layer respectively; the third outer layer pattern production: pattern the added substrate, and then carry out the fourth lamination, the fourth drilling, the fourth laser and the fourth electroplating in sequence. The fourth lamination is to press the L1 layer, the PP sheet, the L2-L11 layer pressed in the previous step, the PP sheet and the L12 layer, that is, to complete the lamination of the L1-L12 layer. The third drilling and the third laser drilling drill holes through the L1-L2 and L11-L12 layers.

[0043] S5: Then, outer layer graphics production and post-processing are performed to prepare a PCB board.

[0044] After all the boards are pressed together, the through holes formed by the first drilling become buried vias, and subsequent drilling and laser forming blind and buried vias.

[0045] The post-process includes solder masking, molding, testing and packaging of the PCB board. In some embodiments, the post-process includes testing of the PCB board, the testing includes reflow soldering and hot and cold shock experiments, and the board is baked before reflow soldering, the baking temperature is 120-140°C, the baking time is 5-7 hours, the baking temperature is preferably 130 degrees Celsius, and the baking time is preferably 6 hours.

[0046] During reflow soldering, the instantaneous temperature in the reflow furnace can reach more than 200 degrees. The water molecules inside the PCB board will be heated and atomized into water vapor. As the temperature rises, the volume of the water vapor will expand rapidly. The higher the temperature, the larger the volume of the atomization. At this time, when the water vapor cannot escape from the PCB immediately, it will expand the PCB board and break the conductive holes between the layers of the PCB. It may also cause separation between the layers of the PCB. In more serious cases, blistering, expansion, and explosion can be seen on the surface of the PCB. Adding a baking process before reflow soldering can avoid the above problems.

[0047] The PCB board was reflowed at 260°C for 6 times, and the resistance change rate obtained by the test was less than 5%. Then, a hot and cold shock test was carried out at a temperature of 35°C to 140°C. After 120 cycles of the test, the resistance change rate obtained by the test was still less than 5%.

[0048] After cutting, before making the inner layer pattern, all substrates are baked for the first time. The first baking temperature is 170-190℃, and the first baking time is 3-5 hours. The first baking temperature is preferably 180 degrees Celsius, and the first baking time is preferably 4 hours. The first baking can prevent the stress between the copper foil on the surface of the substrate and the base material, which will cause deformation and warping of the board during subsequent processing, thereby avoiding the breakage of the hole copper.

[0049] After the first drilling, before the board is electrically connected, the multilayer board after the first pressing is baked for the second time. The second baking temperature is 140-160°C, the second baking time is 1-3 hours, the second baking temperature is preferably 150 degrees Celsius, and the second baking time is preferably 2 hours. The second baking is to eliminate the internal stress of the multilayer board after pressing, stabilize the size of the multilayer board, and prevent the hole copper from breaking due to internal stress.

[0050] After the board is electrified, the third baking is performed before the resin plugging. The temperature of the third baking is 140-160°C, the third baking time is 1-3 hours, the third baking temperature is preferably 150 degrees Celsius, and the third baking time is preferably 2 hours. The third baking can reduce the variable of thermal expansion and contraction of water molecules in the substrate, and avoid the problem of hole copper fracture caused by thermal expansion and contraction of the substrate.

[0051] After the resin plugging, the fourth baking is performed before the cover hole electroplating and / or cap electroplating. The temperature of the fourth baking is 110-150°C and the fourth baking time is 30-60 minutes. The fourth baking is to avoid the delamination of the electroplated layer after the board is electroplated due to the thermal expansion and contraction of the resin ink.

[0052] The resin ink used for resin plugging is PHP-900IR-10FH ink from Shanrong Daily Chemicals Co., Ltd. The resin ink uses ink with a small thermal expansion coefficient, which can reduce the CTE expansion ratio of the resin ink and avoid hole copper fracture.

[0053] In some embodiments, the minimum thickness of the capping electroplating is 25 μm. The minimum thickness of the capping electroplating is 25 μm, which can better fix the ink of the resin plugging hole.

[0054] The present invention provides a method for manufacturing a PCB board with a small hole chain resistance change rate. After cutting, drilling, board electricity and resin plugging, baking is performed and multiple pressings are performed respectively, so that the problem of hole copper breakage can be avoided and the quality of the PCB board is ensured. The manufactured PCB board has a small hole chain resistance change rate and high environmental adaptability after being tested by reflow soldering and hot and cold shock experiments.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0056] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0057] In the description of the present invention, it should be noted that the terms "upper" and "lower" etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of this implementation shall be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a PCB board with a small hole chain resistance change rate, characterized in that: The following steps are included in sequence: Cut all substrates; Make the inner layer pattern, determine that the substrate involved in the buried hole is the Lm-Ln layer, and for the first lamination, place PP sheets between each layer of the board, and laminate the Lm-Ln layer and the PP sheet before lamination; The first drilling forms a through hole, followed by board plating, resin plugging, cover hole plating and / or cap plating; After the cutting, drilling, board bonding and resin plugging, baking is performed; A substrate is added above the Lm layer and below the Ln layer, respectively serving as the Lm-1 layer and the Ln+1 layer; the first outer layer patterning: the patterning is performed on the added substrate, and then the second lamination, the second drilling, the second laser and the second electroplating are performed in sequence; a substrate is added above the Lm-1 layer and below the Ln+1 layer, respectively serving as the Lm-2 layer and the Ln+2 layer; the second outer layer patterning is performed: the patterning is performed on the added substrate, and then the third lamination, the third drilling, the third laser and the third electroplating are performed in sequence; and so on until all the boards are pressed; Then the outer layer pattern production and post-processing are carried out to prepare the PCB board; in, After the cutting, before the inner layer pattern is made, all substrates are first baked, the first baking temperature is 170-190° C., and the first baking time is 3-5 hours; After the first drilling and before the board is electrically bonded, the multilayer board after the first pressing is baked for the second time, the second baking temperature is 140-160° C., and the second baking time is 1-3 hours; After the board is electrified, a third baking is performed before the resin plugging, the third baking temperature is 140-160° C., and the third baking time is 1-3 hours; After the resin plugging, a fourth baking is performed before the cover hole electroplating and / or the cap electroplating, the fourth baking temperature is 110-150° C., and the fourth baking time is 30-60 minutes; The post-process includes testing of the PCB board, including reflow soldering and hot and cold shock experiments. The board is baked before reflow soldering, the baking temperature is 120~140℃, and the baking time is 5~7 hours; The reflow soldering step includes: performing 6 reflow soldering tests on the PCB board at 260° C.; the hot and cold shock test step includes: performing 120 cycle tests on the PCB board at a temperature of 35° C. to 140° C.; and performing a hole chain resistance change rate test in both the reflow soldering step and the hot and cold shock test to ensure that the resistance change rate is less than 5%.

2. The method for manufacturing a PCB board with a small hole chain resistance change rate according to claim 1, characterized in that: The post-process includes solder masking, molding, testing and packaging of PCB boards.

3. The method for manufacturing a PCB board with a small hole chain resistance change rate according to claim 1, characterized in that: The resin ink used for the resin plugging is PHP-900 IR-10FH ink produced by Shanrong Daily Chemicals Co., Ltd.

4. The method for manufacturing a PCB board with a small hole chain resistance change rate according to claim 1, characterized in that: The minimum thickness of the cover hole electroplating is 25 μm.

5. The method for manufacturing a PCB board with a small hole chain resistance change rate according to claim 1, characterized in that: The minimum thickness of the cap electroplating is 25 μm.

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