A method for preparing PCB and PCB

Abstract

The present invention discloses a method for preparing a PCB and a PCB, wherein the method for preparing the PCB comprises the following steps: setting a first hole ring in a preset opening area of ​​a designated core board; setting a water-absorbing resin on a side of the first hole ring away from the designated core board; stacking the designated core board and the first core board and pressing them together to form a multilayer board; drilling holes in the multilayer board corresponding to the preset opening area to form a through hole in the multilayer board; performing chemical copper deposition on the multilayer board to allow the water-absorbing resin to absorb water, and depositing a conductive layer on the hole wall of the through hole; baking the multilayer board to allow the water-absorbing resin to generate water vapor, and the volume of the water-absorbing resin expands and protrudes from the hole wall of the through hole; disconnecting the conductive layer located on the designated core board from the conductive layer located on the first core board. The technical solution of the present invention provides a method for preparing a PCB that completely eliminates the influence of residual piles on signal transmission.

Description

Technical Field

[0001] The present invention relates to the technical field of printed circuit boards, and in particular to a method for preparing a PCB and the PCB. Background Art

[0002] The ineffective hole copper length of the signal via on the PCB (Printed Circuit Board) (usually called via stub) has a great impact on the signal integrity of the signal via. Currently, the length of the stub is reduced by back drilling. If the stub can be completely eliminated (no stub or zero stub), the impact of the stub on signal transmission can be completely eliminated.

[0003] In the related art, in order to achieve a completely stub-free, special lamination and multiple pressing processes are used, or materials with special properties (anti-plating material pressing plates) are used to achieve this. However, the material properties used in the preparation method are generally special, and there are characteristics such as poor compatibility with existing materials and poor compatibility with existing PCB production processes, which affects the preparation of PCBs. Summary of the invention

[0004] The main purpose of the present invention is to provide a PCB preparation method and a PCB, aiming to provide a PCB preparation method that completely eliminates the influence of residual piles on signal transmission.

[0005] To achieve the above object, the method for preparing PCB proposed by the present invention comprises the following steps:

[0006] Setting a first hole ring in a predetermined opening area of ​​the designated core plate;

[0007] Disposing a water-absorbing resin on a side of the first hole ring away from the designated core plate;

[0008] The designated core board and the first core board are stacked and pressed together to form a multilayer board; wherein the water-absorbing resin is located between the designated core board and the first core board;

[0009] Drilling holes in the multilayer board corresponding to the preset opening area to form through holes in the multilayer board; wherein the through holes pass through the first hole ring, and the water-absorbing resin is exposed on the hole wall of the through holes;

[0010] Performing chemical copper deposition on the multilayer board to allow the water-absorbing resin to absorb water, and depositing a conductive layer on the hole wall of the through hole;

[0011] The multilayer board is baked to make the water-absorbing resin generate water vapor, and the water-absorbing resin expands in volume and protrudes from the hole wall surface of the through hole;

[0012] The conductive layer located at the designated core board is disconnected from the conductive layer located at the first core board.

[0013] In one embodiment, after the step of disconnecting the conductive layer located on the designated core board from the conductive layer located on the first core board, the step of removing the conductive layer located on the first core board is further included.

[0014] In one embodiment, the multilayer board also includes a first copper layer arranged on the outside of the first core board and a second copper layer arranged on the outside of the designated core board, and the removal of the conductive layer located on the first core board specifically includes the following steps: forming an isolated copper ring on the first copper layer corresponding to the periphery of the through hole.

[0015] In one embodiment, the forming of the isolated copper ring specifically includes the following steps:

[0016] Preparing a surface dry film pattern on the first copper layer, wherein the dry film pattern includes a copper ring area located at a preset copper ring position and a reserved area at a non-preset copper ring position, wherein there is a gap between the copper ring area and the reserved area;

[0017] The multilayer board is etched to remove the hole copper of the first copper layer corresponding to the gap, so as to form an isolated copper ring on the first copper layer.

[0018] In one embodiment, after the step of forming the isolated copper ring, the following steps are further included:

[0019] Tinning the multilayer board to form a tin layer on the surface of the first copper layer, the surface of the second copper layer, and the surface of the conductive layer located on the designated core board;

[0020] The multilayer board is etched to remove the isolated copper ring and the conductive layer located on the first core board.

[0021] In one embodiment, after the step of etching the multilayer board, the following steps are further included:

[0022] The tin layer is removed.

[0023] In one embodiment, etching the multilayer board to remove the hole copper of the first copper layer corresponding to the gap to form an isolated copper ring in the first copper layer further includes the following steps:

[0024] The dry film pattern is removed.

[0025] In one embodiment, disconnecting the conductive layer located on the designated core board from the conductive layer located on the first core board specifically comprises the following steps:

[0026] Laser ablating the conductive layer located on the water-absorbing resin and / or the water-absorbing resin protruding from the wall of the through hole to disconnect the conductive layer located on the designated core board from the conductive layer located on the first core board; and / or,

[0027] The through hole is cleaned with an alkaline solution to remove the water-absorbing resin, so that the conductive layer located on the designated core board is disconnected from the conductive layer located on the first core board.

[0028] In one embodiment, the water-absorbing resin includes a hydrogel, and the hydrogel includes one or both of sodium polyacrylate and polyacrylamide.

[0029] The present invention further provides a PCB, which is prepared by the above-mentioned PCB preparation method; the PCB preparation method comprises the following steps:

[0030] Setting a first hole ring in a predetermined opening area of ​​the designated core plate;

[0031] Disposing a water-absorbing resin on a side of the first hole ring away from the designated core plate;

[0032] The designated core board and the first core board are stacked and pressed together to form a multilayer board; wherein the water-absorbing resin is located between the designated core board and the first core board;

[0033] Drilling holes in the multilayer board corresponding to the preset opening area to form through holes in the multilayer board; wherein the through holes pass through the first hole ring, and the water-absorbing resin is exposed on the hole wall of the through holes;

[0034] Performing chemical copper deposition on the multilayer board to allow the water-absorbing resin to absorb water, and depositing a conductive layer on the hole wall of the through hole;

[0035] The multilayer board is baked to make the water-absorbing resin generate water vapor, and the water-absorbing resin expands in volume and protrudes from the hole wall surface of the through hole;

[0036] The conductive layer located at the designated core board is disconnected from the conductive layer located at the first core board.

[0037] The technical solution of the present invention first sets a first hole ring on the designated core board, attaches a water-absorbing resin to the first hole ring, and then clamps the water-absorbing resin between the designated core board and the first core board to press them into a multilayer board; drills holes in the multilayer board corresponding to the preset opening area to form a through hole, the through hole passes through the first hole ring, and the water-absorbing resin is exposed on the hole wall of the through hole; chemical copper plating is performed on the multilayer board, so that the water-absorbing resin absorbs water and a conductive layer is deposited on the hole wall of the through hole; then the board is baked to make the water-absorbing resin generate water vapor, the volume of the water-absorbing resin expands and protrudes on the hole wall of the through hole, so that the conductive layer deposited on the hole wall of the through hole cracks; finally, the conductive layer located on the designated core board is disconnected from the conductive layer located on the first core board, so that the conductive layer located on the designated core board is separated from the conductive layer located on the first core board and is not conductive, thereby eliminating the influence of the conductive layer located on the first core board (i.e., the via stump) on the signal transmission of the designated core board.

[0038] The present invention arranges a water-absorbing resin between the designated core board and the first core board, utilizes the water-absorbing resin to absorb water during chemical copper deposition and expand after the board is baked, and then disconnects the conductive layer located on the designated core board from the conductive layer located on the first core board, thereby completely eliminating the influence of the via stump on signal transmission. The PCB preparation method does not use materials with special properties, has good compatibility with existing materials, has good compatibility with the PCB preparation process, and the PCB preparation method is simple, the process is short, and only one pressing is required, and multiple pressing is not required, thereby improving the production efficiency of the PCB. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0040] Figure 1 It is a structural schematic diagram of an embodiment of a method for preparing a PCB of the present invention;

[0041] Figure 2 A schematic diagram of the structure of an embodiment of the core plate, the first hole ring and the water-absorbing resin of the present invention;

[0042] Figure 3 It is a structural schematic diagram of an embodiment of a multilayer board of the present invention;

[0043] Figure 4 It is a structural schematic diagram of an embodiment of the present invention after drilling a multilayer board;

[0044] Figure 5 It is a structural schematic diagram of an embodiment of the multi-layer board after chemical copper deposition of the present invention;

[0045] Figure 6 It is a structural schematic diagram of an embodiment of a multilayer board after baking the board according to the present invention;

[0046] Figure 7 It is a structural schematic diagram of an embodiment of the present invention after removing the water-absorbing resin protruding from the hole wall;

[0047] Figure 8 It is a structural schematic diagram of an embodiment of the present invention after washing away the water-absorbing resin in the multilayer board;

[0048] Fig. 9 A structural schematic diagram of an embodiment of providing a dry film pattern for a multilayer board of the present invention;

[0049] Fig.10It is a structural schematic diagram of an embodiment of forming an isolated copper ring on a multilayer board of the present invention;

[0050] Fig.11 It is a structural schematic diagram of an embodiment of the present invention after the dry film pattern is removed from the multilayer board;

[0051] Fig.12 It is a structural schematic diagram of an embodiment of the multilayer board after tinning of the present invention;

[0052] Fig.13 It is a structural schematic diagram of an embodiment of the present invention after removing invalid hole copper;

[0053] Fig.14 It is a structural schematic diagram of an embodiment of the present invention after the tin layer of the multilayer board is removed.

[0054] Description of Figure Numbers:

[0055]

[0056]

[0057] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0059] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0060] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if the meaning of "and / or" appearing in the full text is to include three parallel schemes, taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0061] The invention provides a method for preparing a PCB.

[0062] Figure 1 is a flow chart of the PCB preparation method of the present invention, Figures 2 to 14 The following are structural schematic diagrams of the PCB preparation process of the present invention.

[0063] In the embodiment of the present invention, please refer to Figure 1 The preparation method of the PCB comprises the following steps:

[0064] S100, setting a first hole ring 310 in a preset opening area of ​​a designated core plate 100;

[0065] S200, disposing a water-absorbing resin 400 on a side of the first hole ring 310 away from the designated core plate 100;

[0066] S300, stacking the designated core board 100 and the first core board 210 and pressing them together to form a multilayer board 10; wherein the water-absorbing resin 400 is located between the designated core board 100 and the first core board 210;

[0067] S400, drilling holes in the preset opening area of ​​the multilayer board 10 to form a through hole 10a in the multilayer board 10; wherein the through hole 10a passes through the first hole ring 310, and the water-absorbing resin 400 is exposed on the hole wall of the through hole 10a;

[0068] S500, performing chemical copper deposition on the multilayer board 10, so that the water-absorbing resin 400 absorbs water, and depositing a conductive layer 500 on the hole wall of the through hole 10a;

[0069] S600, baking the multilayer board 10, so that the water-absorbing resin 400 generates water vapor, and the volume of the water-absorbing resin 400 expands and protrudes from the hole wall surface of the through hole 10a;

[0070] S700 , disconnecting the conductive layer 500 located on the designated core board 100 from the conductive layer 500 located on the first core board 210 .

[0071] For details, please refer to Figure 2 , the manufacturing method of the designated core board 100 may include: inner layer manufacturing, drilling, decontamination, copper plating, electroplating, plugging, micro-etching and other process steps, and the designated core board 100 may also be prepared by the method of preparing PCB in the prior art. In other words, a circuit may also be formed inside the designated core board 100. The designated core board 100 is used to transmit signals. It can be imagined by those skilled in the art that the structure of the first core board 210 may refer to the structural setting of the designated core board 100, or the structures of the first core board 210 and the designated core board 100 may be different from each other.

[0072] Please continue to refer to Figure 2 , the first hole ring 310 can be set on the designated core board 100 in an existing manner. The first hole ring 310 is made of metal, and can be specifically made of copper foil. The number, size and position of the first hole ring 310 can be set according to the specific situation. Before preparing the first hole ring 310, a core board pattern can be prepared on the designated core board 100, and then the first hole ring 310 can be set on the core board pattern, or the first hole ring 310 and the core board pattern can be made at the same time, and there is no specific limitation. In order to obtain a high-quality PCB, the first hole ring 310 can be 0.1mm to 0.2mm larger than the aperture of the through hole 10a on one side.

[0073] Please refer to Figure 2 In step S200, the present invention first attaches the water-absorbing resin 400 to the first hole ring 310, and sets the attachment position and size of the water-absorbing resin 400 according to the position and size of the preset opening. The size of the water-absorbing resin 400 is larger than the opening diameter, so that after the through hole 10a is formed, the water-absorbing resin 400 is exposed on the hole wall of the through hole 10a. There are many ways to attach the water-absorbing resin 400 to the designated core board 100. In one embodiment, the water-absorbing resin 400 is screen-printed on the first hole ring 310.

[0074] Please refer to Figure 3 , put the first core board 210 on the designated core board 100, with the water-absorbing resin 400 facing the first core board 210, stack and press together to form a multilayer board 10. One or both of the first core board 210 and the designated core board 100 can be a multilayer board 10, and the multilayer board 10 formed by pressing together can only include the first core board 210 and the designated core board 100. Please continue to refer to Figure 3, and may also include other core plates, such as a second core plate 220, a third core plate, etc. The second core plate 220 may be located between the first core plate 210 and the designated core plate 100, or located on the side of the first core plate 210 away from the designated core plate 100. It is understandable that the multilayer board 10 may also include a second hole ring 320, and the second hole ring 320 may be disposed on the first core plate 210, or may be clamped between the first core plate 210 and the second core plate 220; wherein the second hole ring 320 is disposed opposite to the first hole ring 310.

[0075] Then, please refer to Figure 4 , a drilling operation is performed on the multilayer board 10, and a hole is drilled in the pre-opening area of ​​the multilayer board 10 according to the position and size of the opening to form a through hole 10a, and the through hole 10a passes through the first hole ring 310. The through hole 10a passes through the water-absorbing resin 400, so that the water-absorbing resin 400 is exposed on the hole wall surface of the through hole 10a, so that the water-absorbing resin 400 can contact with the liquid, so that the water-absorbing resin 400 can absorb the liquid.

[0076] Please refer to Figure 5 After the drilling operation is completed, the multilayer board 10 is subjected to a chemical copper plating operation. The multilayer board 10 is immersed in a copper plating solution. The solution contacts the water-absorbing resin 400 through the through hole 10a, and the water-absorbing resin 400 absorbs water. At the same time, a conductive layer 500 is deposited on the hole wall surface of the through hole 10a. The thickness of the conductive layer 500 is relatively small, which can be 0.3 microns to 0.5 microns.

[0077] In step S600, please refer to Figure 6 By baking the board, the multilayer board 10 is heated to a high temperature, and the water absorbed by the water-absorbing resin 400 evaporates due to the heat, making the water-absorbing resin 400 fluffy and expanding and protruding toward the inner wall of the through hole 10a, so that the conductive layer 500 is cracked, which is convenient for the subsequent disconnection operation of the conductive layer 500. The conductive layer 500 in the cracked part is an incomplete copper layer, which has cracks and exposes part of the water-absorbing resin 400.

[0078] The temperature of the baking plate can be 100° C. to 125° C. as long as it is greater than the evaporation temperature of water, and the baking time is 10 minutes to 20 minutes. In one embodiment, the baking temperature of the multilayer board 10 is 110° C. and the baking time is 15 minutes, thereby achieving the volume expansion of the water-absorbing resin 400, reducing energy consumption and reducing production costs.

[0079] The water-absorbing resin 400 can be made of a variety of materials. In one embodiment, the water-absorbing resin 400 includes a hydrogel, which can quickly absorb water, expand in volume after being heated, and protrude from the hole wall of the through hole 10a. There are also a variety of types of the hydrogel. In one embodiment, the hydrogel can include one or both of sodium polyacrylate and polyacrylamide. It should be noted that the water-absorbing resin 400 can also be other water-absorbing polymer resins, as long as it absorbs water and expands in volume after being heated.

[0080] In order to achieve that the designated core plate 100 and the first core plate 210 are not conductive (the two are not conductive after power is turned on and are independent of each other), please refer to Figure 7 , define the conductive layer 500 located at the designated core board 100 as the effective hole copper 510, and the conductive layer 500 located at the first core board 210 as the invalid hole copper 520, disconnect the effective hole copper 510 from the invalid hole copper 520, so that the conductive layer 500 is discontinuous, so as to prevent the effective hole copper 510 from being connected to the invalid hole copper 520, and achieve zero residual piles of the PCB.

[0081] The technical solution of the present invention first sets a first hole ring 310 on the designated core plate 100, attaches a water-absorbing resin 400 to the first hole ring 310, and then clamps the water-absorbing resin 400 between the designated core plate 100 and the first core plate 210 to form a multilayer plate 10; drills holes corresponding to the preset opening area of ​​the multilayer plate 10 to form a through hole 10a, and the through hole 10a passes through the first hole ring 310 and the water-absorbing resin 400, and the water-absorbing resin 400 is exposed on the hole wall of the through hole 10a After chemical copper deposition on the multilayer board 10, the board is baked to make the water-absorbing resin 400 generate water vapor, and the volume of the water-absorbing resin 400 expands and protrudes from the hole wall of the through hole 10a, so that the conductive layer 500 deposited on the hole wall of the through hole 10a is cracked; finally, the effective hole copper 510 and the invalid hole copper 520 are disconnected to achieve separation and non-conduction of the effective hole copper 510 and the invalid hole copper 520, thereby eliminating the influence of the invalid hole copper 520 (i.e., the via stump) on the signal transmission of the designated core board 100.

[0082] The present invention arranges a water-absorbing resin 400 between the designated core board 100 and the first core board 210, utilizes the water-absorbing resin 400 to absorb water during chemical copper deposition and expand after the board is baked, and then disconnects the effective hole copper 510 and the invalid hole copper 520, thereby completely eliminating the influence of the invalid hole copper 520 on signal transmission. The PCB preparation method does not use materials with special properties, has good compatibility with existing materials, has good compatibility with the PCB preparation process, and has a simple PCB preparation method, a short process, and only one pressing, and does not require multiple pressing, thereby improving the production efficiency of the PCB.

[0083] In order to ensure the reliability of disconnection and avoid invalid copper hole 520 affecting signal transmission, please refer to Figure 7In one embodiment, after the step of disconnecting the conductive layer 500 located on the designated core board 100 from the conductive layer 500 located on the first core board 210 , the step of removing the ineffective hole copper 520 of the multilayer board 10 is also included.

[0084] After the effective copper via 510 is disconnected from the ineffective copper via 520, the ineffective copper via 520 of the multilayer board 10 is removed, so that the multilayer board 10 has no residual piles, further avoiding the influence of the ineffective copper via 520 on signal transmission, improving the reliability of signal transmission and ensuring product performance.

[0085] Please refer to Figures 3 to 5 In one embodiment, the multilayer board 10 further includes a first copper layer 610 and a second copper layer 620, and the steps of forming the multilayer board 10 include: stacking the first copper layer 610, the first core board 210, the designated core board 100 and the second copper layer 620 in sequence, and pressing the boards.

[0086] Please refer to Figure 3 The first copper layer 610 is located on the side of the first core board 210 away from the designated core board 100, and the second copper layer 620 is located on the side of the designated core board 100 away from the first core board 210. After lamination, the first copper layer 610 and the second copper layer 620 are respectively located on the upper and lower surfaces of the multilayer board 10. It can be understood that the first copper layer 610 can be a copper foil, which can be stacked on the first core board 210 during lamination, or can be prepared on the surface of the first core board 210 when the first core board 210 is manufactured; similarly, the second copper layer 620 can be stacked on the designated core board 100 during lamination, or can be prepared on the surface of the designated core board 100 when the designated core board 100 is manufactured.

[0087] Since the multilayer board 10 includes a first copper layer 610 and a second copper layer 620, please refer to Figure 5 In the operation of chemical copper deposition, the deposited conductive layer 500 is connected to the first copper layer 610 and the second copper layer 620 respectively, that is, the first copper layer 610 is connected to the second copper layer 620 through the conductive layer 500 .

[0088] The first copper layer 610 located at the periphery of the through hole 10a and the ineffective hole copper 520 can be removed, please refer to Fig.11 In one embodiment, the removing of the conductive layer 500 located on the first core board 210 specifically includes the following steps: forming an isolated copper ring 630 on the first copper layer 610 corresponding to the periphery of the through hole 10a.

[0089] Please refer to Fig.11The copper ring 630 is separated from the first copper layer 610 far from the through hole 10a. By forming an isolated copper ring 630 on the first copper layer 610, the first copper layer 610 is not connected to the copper ring 630, and further to the invalid hole copper 520. On the one hand, it is convenient to remove the invalid hole copper 520 in the subsequent process; on the other hand, the first copper layer 610 is not affected by the invalid hole copper 520, so the function of the first copper layer 610 is guaranteed.

[0090] There are many ways to form an isolated copper ring 630, please refer to Figures 9 and 10 In one embodiment, the forming of the isolated copper ring 630 specifically includes the following steps:

[0091] A surface dry film pattern 700 is prepared on the multilayer board 10, wherein the dry film pattern 700 includes a copper ring area 710 covering the position of the preset copper ring 630 and a surface pattern area 720 not covering the position of the preset copper ring 630, wherein a gap 700a exists between the copper ring area 710 and the reserved area 720;

[0092] The multilayer board 10 is etched to remove the hole copper of the first copper layer 610 corresponding to the gap 700 a , so as to form an isolated copper ring 630 on the first copper layer 610 .

[0093] Please refer to Fig.10 The dry film pattern 700 is arranged on the surfaces of the first copper layer 610 and the second copper layer 620. Since an isolated copper ring 630 needs to be formed on the first copper layer 610, the dry film pattern 700 includes a copper ring area 710 located at a preset copper ring 630 position and a reserved area 720 at a non-preset copper ring 630 position. The gap 700a between the copper ring area 710 and the reserved area 720 forms a closed ring, so that etching can be performed along the ring gap 700a later to remove the hole copper of the first copper layer 610 corresponding to the gap 700a, so that the first copper layer 610 forms an isolated copper ring 630 at the periphery of the through hole 10a.

[0094] That is, please refer to Figures 9 and 10 The first copper layer 610 that does not need to be etched is protected by the dry film pattern 700, and the first copper layer 610 not covered by the dry film pattern 700 is etched, thereby forming an isolated copper ring 630 on the first copper layer 610. It is understood that the dry film pattern 700 can be made by a conventional dry film method.

[0095] To facilitate subsequent processing operations, please refer to Figure 10 to Figure 11In one embodiment, the etching of the multilayer board 10 to remove the hole copper of the first copper layer 610 corresponding to the gap 700a to form an isolated copper ring 630 on the first copper layer 610 also includes the following steps: removing the dry film pattern 700. Specifically, an alkaline solution or an organic solvent can be used to completely dissolve and remove the dry film pattern 700 on the surface of the multilayer board 10, thereby exposing the first copper layer 610, the second copper layer 620 and the isolated copper ring 630.

[0096] Please refer to Figure 12 to Figure 13 In one embodiment, after the step of forming the isolated copper ring 630, the following steps are further included:

[0097] Tinning the multilayer board 10 to form a tin layer 800 on the surface of the first copper layer 610 , the surface of the second copper layer 620 , and the surface of the conductive layer 500 located on the designated core board 100 ;

[0098] The multilayer board 10 is etched to remove the isolated copper ring 630 and the invalid hole copper 520 .

[0099] Please refer to Figures 11 to 13 , since the isolated copper ring 630 is not conductive with the first copper layer 610, the invalid hole copper 520 is not conductive with the effective hole copper 510, and no current passes, the isolated copper ring 630 and the invalid hole copper 520 cannot be tinned, so that a tin layer 800 is formed on the surface of the first copper layer 610, the surface of the second copper layer 620, and the surface of the effective hole copper 510. The etching protection layer is formed by tinning to protect the first copper layer 610, the second copper layer 620, and the effective hole copper 510 from being removed by etching. In this way, the isolated copper ring 630 and the invalid hole copper 520 are removed by etching, which meets the different needs of the product and also realizes the product without residual piles. It should be noted that in addition to tinning, the multilayer board 10 can also be copper-plated to form a copper layer on the surface of the first copper layer 610, the surface of the second copper layer 620, and the surface of the effective hole copper 510.

[0100] After removing the ineffective hole copper 520 and the copper ring 630, the tin layer 800 may be removed or not. Fig.13 and Fig.14 In one embodiment, after etching the multilayer board 10, the following step is further included: removing the tin layer 800 of the multilayer board 10. By removing the protective tin layer 800, the effective hole copper 510, the first copper layer 610 and the second copper layer 620 on the inner wall of the through hole 10a are exposed, so as to facilitate the subsequent normal process production.

[0101] Please refer to Figures 6 to 8 In one embodiment, disconnecting the invalid copper via 520 from the valid copper via 510 specifically includes the following steps:

[0102] Laser ablation of the conductive layer 500 located on the water-absorbing resin 400 and / or the water-absorbing resin 400 protruding from the hole wall of the through hole 10a to disconnect the ineffective hole copper 520 from the effective hole copper 510; and / or,

[0103] The through hole 10 a is cleaned with an alkaline solution to remove the water absorbing resin 400 , so that the ineffective hole copper 520 is disconnected from the effective hole copper 510 .

[0104] Please refer to Figure 6 to Figure 7 , the conductive layer 500 located on the water-absorbing resin 400 is removed by laser ablation, so that the invalid hole copper 520 is disconnected from the effective hole copper 510. Alternatively, the water-absorbing resin 400 protruding from the inner wall of the through hole 10a is removed, thereby removing the conductive layer 500 located on the water-absorbing resin 400, so as to disconnect the invalid hole copper 520 from the effective hole copper 510.

[0105] Please refer to Figure 8 , since the volume of the water-absorbing resin 400 expands after being heated, it protrudes into the through hole 10a, causing the conductive layer 500 to crack, and the cracked portion of the conductive layer 500 is an incomplete copper layer, exposing part of the water-absorbing resin 400. Therefore, the water-absorbing resin 400 located on the multilayer board 10 is washed away by soaking and cleaning with an alkaline solution, so that the conductive layer 500 located on the water-absorbing resin 400 loses the attached body and falls off, thereby achieving the disconnection of the invalid hole copper 520 and the effective hole copper 510.

[0106] Alternatively, laser ablation may be performed first to remove the conductive layer 500 located on the water-absorbing resin 400 and / or the water-absorbing resin 400 protruding from the inner wall of the through hole 10a, and then the water-absorbing resin 400 may be washed away, thereby completely removing the water-absorbing resin 400, so that the ineffective hole copper 520 is completely disconnected and separated from the effective hole copper 510.

[0107] The present invention also provides a PCB, which is prepared by the above-mentioned PCB preparation method. The specific method of the PCB refers to the above-mentioned embodiment. Since the PCB adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here. Among them, the PCB is a circuit board without residual piles, and the "no residual piles" here can mean that there are no residual piles, or it can also mean that it is not affected by the residual piles.

[0108] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a PCB, characterized in that: The following steps are involved: Disposing a first hole ring (310) in a preset opening area of ​​a designated core plate (100); A water-absorbing resin (400) is disposed on a side of the first hole ring (310) facing away from the designated core plate (100); The designated core board (100) and the first core board (210) are stacked and pressed together to form a multilayer board (10); wherein the water-absorbing resin (400) is located between the designated core board (100) and the first core board (210); Drilling holes in the multilayer board (10) corresponding to the preset opening area to form a through hole (10a) in the multilayer board (10); wherein the through hole (10a) passes through the first hole ring (310), and the water-absorbing resin (400) is exposed on the hole wall of the through hole (10a); Performing chemical copper plating on the multilayer board (10) so that the water-absorbing resin (400) absorbs water, and depositing a conductive layer (500) on the hole wall of the through hole (10a); The multilayer board (10) is baked to cause the water-absorbing resin (400) to generate water vapor, and the water absorbed by the water-absorbing resin (400) evaporates due to heat, so that the water-absorbing resin (400) becomes fluffy, and the volume of the water-absorbing resin (400) expands and protrudes from the hole wall surface of the through hole (10a); The conductive layer (500) located on the designated core board (100) is disconnected from the conductive layer (500) located on the first core board (210).

2. The method for preparing a PCB according to claim 1, characterized in that: After the step of disconnecting the conductive layer (500) located on the designated core board (100) from the conductive layer (500) located on the first core board (210), the following steps are also included: The conductive layer (500) located on the first core board (210) is removed.

3. The method for preparing a PCB according to claim 2, characterized in that: The multilayer board (10) further comprises a first copper layer (610) arranged on the outside of the first core board (210) and a second copper layer (620) arranged on the outside of the designated core board (100), and the removing of the conductive layer (500) located on the first core board (210) specifically comprises the following steps: An isolated copper ring (630) is formed on the first copper layer (610) corresponding to the periphery of the through hole (10a).

4. The method for preparing a PCB according to claim 3, characterized in that: The forming of the isolated copper ring (630) specifically comprises the following steps: Preparing a dry film pattern (700) on the surface layer on the first copper layer (610), the dry film pattern (700) comprising a copper ring area (710) located at a preset copper ring (630) position and a reserved area (720) at a non-preset copper ring (630) position, wherein a gap (700a) exists between the copper ring area (710) and the reserved area (720); The multilayer board (10) is etched to remove the hole copper of the first copper layer (610) corresponding to the gap (700a), so as to form an isolated copper ring (630) in the first copper layer (610).

5. The method for preparing a PCB according to claim 4, characterized in that: After the step of forming the isolated copper ring (630), the following steps are also included: Tinning the multilayer board (10) to form a tin layer (800) on the surface of the first copper layer (610), the surface of the second copper layer (620), and the surface of the conductive layer (500) located on the designated core board (100); The multilayer board (10) is etched to remove the isolated copper ring (630) and the conductive layer (500) located on the first core board (210).

6. The method for preparing a PCB according to claim 5, characterized in that: After the step of etching the multilayer board (10), the following steps are also included: The tin layer (800) is removed.

7. The method for preparing a PCB according to claim 5, characterized in that: The etching of the multilayer board (10) to remove the hole copper of the first copper layer (610) corresponding to the gap (700a) to form an isolated copper ring (630) in the first copper layer (610) also includes the following steps: The dry film pattern (700) is removed.

8. The method for preparing a PCB according to any one of claims 1 to 7, characterized in that: The step of disconnecting the conductive layer (500) located on the designated core board (100) from the conductive layer (500) located on the first core board (210) specifically comprises the following steps: Laser ablating the conductive layer (500) located on the water-absorbing resin (400) and / or the water-absorbing resin (400) protruding from the hole wall of the through hole (10a) to disconnect the conductive layer (500) located on the designated core board (100) from the conductive layer (500) located on the first core board (210); and / or, The through hole (10a) is cleaned with an alkaline solution to remove the water-absorbing resin (400), thereby disconnecting the conductive layer (500) located on the designated core board (100) from the conductive layer (500) located on the first core board (210).

9. The method for preparing a PCB according to any one of claims 1 to 7, characterized in that: The water-absorbing resin (400) includes a hydrogel, and the hydrogel includes one or both of sodium polyacrylate and polyacrylamide.

10. A PCB, characterized in that: The PCB is prepared by the method for preparing the PCB according to any one of claims 1 to 9.

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