Printed circuit board (PCB)

Abstract

The utility model discloses a PCB (Printed Circuit Board), which comprises a top surface copper foil layer, a bottom surface copper foil layer, a top surface brazing layer, a bottom surface brazing layer and tin columns corresponding to via holes, and the top surface brazing bottoming copper layer and the bottom surface brazing bottoming copper layer of a substrate are respectively attached to the top surface and the bottom surface of a core plate; the bottom surface of the top surface copper foil layer is welded on the brazing bottoming copper layer on the top surface of the substrate through the top surface brazing layer, and the top surface of the bottom surface copper foil layer is welded on the brazing bottoming copper layer on the bottom surface of the substrate through the bottom surface brazing layer; the top surface of the tin column is welded with the bottom surface of the top surface copper foil layer, and the bottom surface of the tin column is welded with the top surface of the bottom surface copper foil layer; the top surface circuit layer comprises the top surface copper foil layer, a top surface brazing layer and a brazing bottoming copper layer on the top surface of the substrate, and the bottom surface circuit layer comprises the bottom surface copper foil layer, a bottom surface brazing layer and a brazing bottoming copper layer on the bottom surface of the substrate. According to the utility model, the conduction resistance of the via hole is reduced, the heat conduction efficiency between the conduction layers of the PCB is improved, and the reliability of the PCB is improved.

Description

[Technical field]

[0001] The utility model relates to a circuit board, in particular to a PCB board. [Background Technology]

[0002] The function of PCB vias is to achieve electrical connection and signal transmission between different layers through solder holes or connection holes on the PCB. These holes are enhanced in conductivity through processes such as electroplating to connect different circuit components or different PCB layers.

[0003] Vias are generally plated holes, that is, holes with metal plated on the hole wall. Plated holes can achieve electrical connections between conductive patterns on the inner layer, outer layer, or inner and outer layers of the PCB board. Filling holes in PCB boards is a complicated and laborious task. For example, it usually takes 4 hours to electroplating holes in ceramic boards, which is inefficient and has the risk of not being completely filled. Because the traditional copper plating hole filling process is very inefficient, when designing through holes, the hole diameter can only be reduced, which reduces the cross-sectional area of ​​the conductive copper column, increases the on-resistance, reduces the thermal conductivity, and has a negative impact on product performance. For ceramic circuit boards, when the filled hole copper is subjected to high temperature shock, the tension of thermal expansion will also cause the hole to crack.

[0004] The invention with application number 201510506287.X discloses a method for manufacturing a PCB board and a PCB board, including the following steps: drilling a plug hole on a substrate; plating a first copper layer on the substrate surface and copper plating on the inner wall of the plug hole; filling the plug hole with resin until it protrudes from the plug hole opening; performing a material reduction treatment on the resin protruding from the opening so that the surface of the resin protruding from the opening is flush with the surface of the first copper layer; drilling a non-plug hole on the substrate; plating a second copper layer on the first copper layer and copper plating on the inner wall of the non-plug hole; transferring the substrate pattern; etching the substrate to form a conductive circuit. The PCB board manufactured by the above manufacturing method has a very clean interior of the non-plug hole that is too close to the plug hole. When the PCB board is tested for continuity, after the probe detects the non-plug hole, it can be in close contact with the conductive copper layer on the wall of the non-plug hole to conduct. The disadvantage of using resin to fill the copper-plated hole is that the resin cannot conduct electricity, and the heat dissipation performance of the conductive performance of the resin-filled via is poor. The thermal resistance of the on-resistance is large. In order to meet the requirements of larger current conduction and interlayer heat dissipation, the resin-filled copper-plated holes need to have a larger aperture, and the plating layer on the inner wall of the via must be thick enough, which reduces the efficiency of via electroplating and increases the cost of the PCB board. [Summary of the invention]

[0005] The technical problem to be solved by the utility model is to provide a PCB board with good through-hole electrical and thermal conductivity.

[0006] In order to solve the above technical problems, the technical solution adopted by the utility model is: a PCB board, including a substrate, a top circuit layer and a bottom circuit layer, the substrate including at least one via hole; the PCB board also includes a top copper foil layer, a bottom copper foil layer, a top brazing layer, a bottom brazing layer and tin columns corresponding to the via holes, the substrate includes a core board, a brazing primer copper layer on the top surface of the substrate and a brazing primer copper layer on the bottom surface of the substrate, the top brazing primer copper layer and the bottom brazing primer copper layer are respectively attached to the top surface and the bottom surface of the core board; the bottom surface of the top copper foil layer is welded to the brazing primer copper layer on the top surface of the substrate through the top brazing layer, and the top surface of the bottom copper foil layer is welded to the brazing primer copper layer on the top surface of the substrate through the top brazing layer The bottom soldering layer is welded on the soldering primer copper layer on the bottom surface of the substrate; the inner wall of the via hole includes the via copper plating layer, the tin column is formed by melting the tin paste filled in the via hole, the top surface of the tin column is welded to the bottom surface of the top copper foil layer through the top soldering layer, and the side surface of the tin column is fused to the via copper plating layer of the corresponding via hole; the via hole includes a through hole, and the bottom surface of the tin column in the through hole is welded to the top surface of the bottom copper foil layer through the bottom soldering layer; the top circuit layer includes the top copper foil layer, the top soldering layer and the soldering primer copper layer on the top surface of the substrate, and the bottom circuit layer includes the bottom copper foil layer, the bottom soldering layer and the soldering primer copper layer on the bottom surface of the substrate.

[0007] The PCB board described above, the substrate includes a double-sided board, a top copper-plated layer and a bottom copper-plated layer, the double-sided board includes a core board of organic material, an upper copper foil and a lower copper foil, the core board of the double-sided board of organic material is the core board of the substrate, the top copper-plated layer is plated on the top surface of the upper copper foil of the double-sided board, and the bottom copper-plated layer is plated on the bottom surface of the lower copper foil of the double-sided board; the soldering primer copper layer on the top surface of the substrate includes the top copper-plated layer and the upper copper foil, and the soldering primer copper layer on the bottom surface of the substrate includes the bottom copper-plated layer and the lower copper foil.

[0008] The PCB board described above, the core board of the double-sided board made of organic material includes an intermediate circuit layer, the vias include blind holes whose lower ends reach the intermediate circuit layer and / or the through holes passing through the intermediate circuit layer, the bottom surface of the tin column in the blind hole is fused to the intermediate circuit layer below the blind hole, and the tin column in the through hole passing through the intermediate circuit layer is fused to the intermediate circuit layer.

[0009] The thickness of the top soldering layer and the bottom soldering layer of the PCB board described above is 0.05-10 μm.

[0010] In the PCB board described above, the core board is a ceramic core board, and the brazing base copper layer includes a sputtered copper layer, and the sputtered copper layer includes a sputtered copper layer sputtered on the outer surface of the ceramic core board and a copper plated layer plated on the outer surface of the sputtered copper layer.

[0011] In the above-mentioned PCB board, the sputtered copper layer includes a transition metal layer sputtered on the outer surface of the ceramic core board and a copper layer sputtered on the outer surface of the transition metal layer.

[0012] In the above-mentioned PCB board, the via-hole copper plating layer includes a sputtered copper layer sputtered on the inner wall of the via-hole and a copper plating layer plated on the inner surface of the sputtered copper layer on the inner wall of the via-hole.

[0013] In the above-mentioned PCB board, the top copper foil layer includes a pad, the via hole is a via in the pad, and the top surface of the tin column in the via in the pad is welded to the bottom surface of the pad through the top soldering layer.

[0014] The PCB board of the utility model fills tin pillars in the copper-plated via holes, thereby reducing the conduction resistance of the via holes, improving the heat conduction efficiency between the conduction layers of the PCB board, and improving the reliability of the PCB board. [Drawings]

[0015] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0016] Figure 1 It is a partial cross-sectional view of the PCB board of Example 1 of the utility model.

[0017] Figure 2 It is a partial cross-sectional view of the PCB board of Example 2 of the utility model.

[0018] Figure 3 It is a partial cross-sectional view of the PCB board of Example 3 of the utility model. [Specific implementation method]

[0019] The structure of the PCB board in the utility model embodiment 1 is as follows Figure 1 As shown, the PCB board includes a substrate 10, a top circuit layer 20 and a bottom circuit layer 30, and a via 40 is provided in the substrate 10. The PCB board also includes a top copper foil layer 21, a bottom copper foil layer 31, a top soldering layer 22, a bottom soldering layer 32 and a tin column 41 in the via 40. The thickness of the top soldering layer 22 and the bottom soldering layer 32 is 0.05 to 10 μm.

[0020] The substrate 10 includes a core board, a soldering copper layer 10B on the top surface of the substrate 10 and a soldering copper layer 10C on the bottom surface of the substrate 10. The top soldering copper layer 10B and the bottom soldering copper layer 10C are attached to the top and bottom surfaces of the core board respectively.

[0021] The bottom surface of the top copper foil layer 21 is welded to the soldering primer copper layer 10B on the top surface of the substrate 10 via the top solder layer 22 , and the top surface of the bottom copper foil layer 31 is welded to the soldering primer copper layer 10C on the bottom surface of the substrate 10 via the bottom solder layer 32 .

[0022] The inner wall of the via hole 40 includes a copper plating layer 42 of the via hole 40, the tin pillar 41 is formed by melting the tin paste filled in the via hole 40, the top surface of the tin pillar 41 is welded to the bottom surface of the top copper foil layer 21 through the top soldering layer 22, and the side of the tin pillar 41 is welded to the copper plating layer 42 of the inner wall of the corresponding via hole 40. The via hole 40 in Example 1 is a through hole, and the bottom surface of the tin pillar 41 in the through hole is welded to the top surface of the bottom copper foil layer 31 through the bottom soldering layer 32. The top circuit layer 20 includes the top copper foil layer 21, the top soldering layer 22 and the soldering primer copper layer 10B on the top surface of the substrate 10, and the bottom circuit layer 30 includes the bottom copper foil layer 31, the bottom soldering layer 32 and the soldering primer copper layer 10C on the bottom surface of the substrate 10.

[0023] In Example 1, the substrate 10 includes a double-sided board 10A, a top copper plating layer 14 and a bottom copper plating layer 15. The double-sided board 10A includes an organic core board 11, an upper copper foil 12 and a lower copper foil 13. The organic core board 11 of the double-sided board 10A is the core board of the substrate 10. The top copper plating layer 14 is plated on the top surface of the upper copper foil 12 of the double-sided board 10A, and the bottom copper plating layer 15 is plated on the bottom surface of the lower copper foil 13 of the double-sided board 10A. The soldering primer copper layer 10B on the top surface of the substrate 10 includes the top copper plating layer 14 and the upper copper foil 12, and the soldering primer copper layer 10C on the bottom surface of the substrate 10 includes the bottom copper plating layer 15 and the lower copper foil 13.

[0024] The top copper foil layer 21 includes a pad 23 , and the via hole 40 is a via in the pad. The top surface of the tin column 41 in the via in the pad is welded to the bottom surface of the pad 23 through the top soldering layer 22 .

[0025] The manufacturing process of the PCB board of the utility model embodiment 1 is as follows:

[0026] 1) Drilling through holes (vias 40) in the double-sided board 10A;

[0027] 2) copper plating is performed on the inner wall of the through hole of the double-sided board 10A, the outer surface of the upper copper foil 12 and the lower copper foil 13 to form a copper plating layer 42, a top copper plating layer 14 and a bottom copper plating layer 15;

[0028] 3) Filling the copper-plated via 40 with solder paste, and after the substrate 10 is reflowed, the solder paste filled in the via 40 is melted and solidified to form a solder column;

[0029] 4) coating a solder layer on the top and bottom surfaces of the substrate 10 respectively;

[0030] 5) vacuum brazing the top copper foil layer 21 and the bottom copper foil layer 31 on the solder layers coated on the top and bottom surfaces of the substrate 10, respectively;

[0031] 6) performing circuit exposure and etching on the top surface and the bottom surface of the blank respectively to form a top surface circuit layer and a bottom surface circuit layer;

[0032] 7) Perform solder mask and pad surface treatment on the top and bottom surfaces of the PCB board respectively.

[0033] The structure of the PCB board in the second embodiment of the utility model is as follows Figure 2 As shown, the structure of the PCB board in Example 2 is basically the same as that of the PCB board in Example 1, with the main difference being that the core board 11 of the double-sided board 10A made of organic material includes an intermediate circuit layer 16, the via 40 includes a blind hole 40B whose lower end reaches the intermediate circuit layer 16 and the through hole 40B passing through the intermediate circuit layer 16, the bottom surface of the tin column 41 in the blind hole 40B is fused to the intermediate circuit layer 16 below the blind hole 40B, and the side surface of the tin column 41 in the through hole 40A passing through the intermediate circuit layer 16 is fused to the intermediate circuit layer 16.

[0034] The structure of the PCB board in the utility model embodiment 3 is as follows Figure 3 As shown, the structure of the PCB board of Example 3 is basically the same as that of the PCB board of Example 1, and the main difference is that the core board 11 is a ceramic core board. The substrate 10 also includes the core board 11, the brazing primer copper layer 10B on the top surface of the substrate 10, and the brazing primer copper layer 10C on the bottom surface of the substrate 10, but the brazing primer copper layer 10B on the top surface of the substrate 10 and the brazing primer copper layer 10C on the bottom surface of the substrate 10 are both sputtered copper-plated layers, and the sputtered copper-plated layers include a sputtered copper layer 17 sputtered on the outer surface of the ceramic core board 11 and a copper-plated layer 18 plated on the outer surface of the sputtered copper layer 17. The sputtered copper layer 17 includes a transition metal layer sputtered on the outer surface of the ceramic core board and a copper layer sputtered on the outer surface of the transition metal layer, and the metal of the transition metal layer is titanium, nickel or chromium. In addition, the copper plating layer of the via hole 40 includes a sputtered copper layer 43 sputtered on the inner wall of the via hole 40 and a copper plating layer 42 plated on the inner surface of the sputtered copper layer 43 on the inner wall of the via hole 40 .

[0035] The manufacturing process of the PCB board of the utility model embodiment 3 is as follows:

[0036] 1) drilling a through hole (via 40) on a ceramic core board serving as a core board;

[0037] 2) vacuum sputtering copper is plated on the inner wall of the through hole of the ceramic core board, the top surface and the bottom surface of the ceramic core board to form a sputtered copper layer 43 and a copper plating layer 42 on the inner wall of the through hole 40, a brazing primer copper layer 10B on the top surface of the substrate 10, and a brazing primer copper layer 10C on the bottom surface of the substrate 10;

[0038] 3) Filling the via hole 40 plated with vacuum sputtering copper with solder paste, and after the substrate 10 is reflowed, the solder paste filled in the via hole 40 is melted and solidified to form a solder column;

[0039] 4) coating a solder layer on the top and bottom surfaces of the substrate 10 respectively;

[0040] 5) vacuum brazing the top copper foil layer 21 and the bottom copper foil layer 31 on the solder layers coated on the top and bottom surfaces of the substrate 10, respectively;

[0041] 6) performing circuit exposure and etching on the top surface and the bottom surface of the blank respectively to form a top surface circuit layer and a bottom surface circuit layer;

[0042] 7) Perform solder mask and pad surface treatment on the top and bottom surfaces of the PCB board respectively.

[0043] The PCB board of the above embodiment of the utility model fills tin pillars in the copper-plated via holes, which reduces the on-resistance of the via holes, improves the heat conduction efficiency between the conductive layers of the PCB board, and improves the reliability of the PCB board. For ceramic circuit boards, the tin pillars filled in the via holes can reduce the risk of cracking of the ceramic circuit board because the thermal expansion force of the tin pillars is much smaller than that of the copper pillars.

Claims

1. A PCB board, comprising a substrate, a top circuit layer and a bottom circuit layer, wherein the substrate comprises at least one via hole, characterized in that: The invention comprises a top copper foil layer, a bottom copper foil layer, a top brazing layer, a bottom brazing layer and tin pillars corresponding to the via holes. The substrate comprises a core board, a brazing primer copper layer on the top surface of the substrate and a brazing primer copper layer on the bottom surface of the substrate. The top brazing primer copper layer and the bottom brazing primer copper layer are attached to the top surface and the bottom surface of the core board respectively. The bottom surface of the top copper foil layer is welded to the brazing primer copper layer on the top surface of the substrate through the top brazing layer, and the top surface of the bottom copper foil layer is welded to the brazing primer copper layer on the bottom surface of the substrate through the bottom brazing layer. The inner wall of the via hole comprises a via hole copper plating layer. The via hole comprises a through hole, the bottom surface of the tin column in the through hole is welded with the top surface of the bottom copper foil layer through the bottom soldering layer; the top circuit layer comprises the top copper foil layer, the top soldering layer and the soldering primer copper layer on the top surface of the substrate; the bottom circuit layer comprises the bottom copper foil layer, the bottom soldering layer and the soldering primer copper layer on the bottom surface of the substrate.

2. The PCB board according to claim 1, characterized in that: The substrate comprises a double-sided board, a top copper-plated layer and a bottom copper-plated layer, the double-sided board comprises a core board of organic material, an upper copper foil and a lower copper foil, the core board of the double-sided board of organic material is the core board of the substrate, the top copper-plated layer is plated on the top surface of the upper copper foil of the double-sided board, and the bottom copper-plated layer is plated on the bottom surface of the lower copper foil of the double-sided board; the soldering primer copper layer on the top surface of the substrate comprises the top copper-plated layer and the upper copper foil, and the soldering primer copper layer on the bottom surface of the substrate comprises the bottom copper-plated layer and the lower copper foil.

3. The PCB board according to claim 2, characterized in that: The core board of the double-sided board made of organic material includes an intermediate circuit layer, and the vias include blind holes whose lower ends reach the intermediate circuit layer and / or through holes passing through the intermediate circuit layer, the bottom surface of the tin column in the blind hole is fused to the intermediate circuit layer below the blind hole, and the tin column in the through hole passing through the intermediate circuit layer is fused to the intermediate circuit layer.

4. The PCB board according to claim 1, characterized in that: The thickness of the top solder layer and the bottom solder layer is 0.05 to 10 μm.

5. The PCB board according to claim 1, characterized in that: The core board is a ceramic core board, the brazing base copper layer includes a sputtering copper layer, and the sputtering copper layer includes a sputtering copper layer sputtered on the outer surface of the ceramic core board and a copper plated layer plated on the outer surface of the sputtering copper layer.

6. The PCB board according to claim 5, characterized in that: The sputtered copper layer comprises a transition metal layer sputtered on the outer surface of the ceramic core plate and a copper layer sputtered on the outer surface of the transition metal layer.

7. The PCB board according to claim 5, characterized in that: The via hole copper plating layer comprises a sputtered copper layer sputtered on the inner wall of the via hole and a copper plating layer plated on the inner surface of the sputtered copper layer on the inner wall of the via hole.

8. The PCB board according to claim 1, characterized in that: The top copper foil layer includes a pad, the via hole is a hole in the pad, and the top surface of the tin column in the hole in the pad is welded to the bottom surface of the pad through the top soldering layer.

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