Circuit board processing technology, circuit board and battery module applying circuit board

Abstract

A circuit board processing technology comprises the following steps that a circuit substrate is provided, the circuit substrate comprises a dielectric layer, an aluminum circuit layer arranged on one side of the dielectric layer and a covering film, the covering film covers the aluminum circuit layer and is combined with the dielectric layer, the aluminum circuit layer comprises an electric connection pad, and the electric connection pad is exposed out of the covering film; a copper plating layer is formed on the electric connection pad, exposed out of the covering film, of the circuit substrate; and forming a nickel plating layer on the copper plating layer. According to the circuit board treatment process, the quality of the nickel coating can be improved. The invention also provides a circuit board and a battery module using the circuit board.

Description

Technical Field

[0001] The present application relates to the field of circuit boards, and in particular to a circuit board processing process, a circuit board, and a battery module using the circuit board. Background Art

[0002] With the development of the product era and the changes in application scenarios, flexible aluminum printed circuit boards are widely used in mechanical hard disks, and now there is a trend of being used in new energy vehicle battery modules. When flexible aluminum printed circuit boards are used in batteries, the circuit boards are usually laser welded to the battery bus with the help of nickel sheets or laser welded to the battery bus after nickel plating on the circuit boards. Due to the strong activity of aluminum metal, it is very easy to form a passivation layer (Al2O3) in the air. The presence of this passivation layer greatly reduces the welding strength and even causes welding failure and part peeling. In order to reduce the risks caused by aluminum oxidation, a layer of zinc is usually plated on the aluminum layer before entering the chemical nickel plating tank. The zinc layer quickly and completely dissolves after entering the chemical nickel plating tank, and at the same time, a nickel layer is chemically plated. As the amount of aluminum plates entering the chemical nickel plating tank increases, the zinc ions and aluminum ions in the tank will increase. When the zinc ions reach a certain amount, the nickel layer will become uneven in color, brittle, and even produce pinholes. Aluminum ions also affect the quality of the nickel layer. At the same time, the life of the nickel tank will be greatly shortened, and the zinc layer will also inhibit the reaction in the chemical nickel plating tank. Summary of the invention

[0003] In view of this, it is necessary to provide a circuit board processing process that solves the above problems. In addition, a circuit board and a battery module using the circuit board are also provided.

[0004] The first aspect of the present application provides a circuit board processing process, comprising the following steps: providing a circuit substrate, comprising a dielectric layer, an aluminum circuit layer arranged on one side of the dielectric layer, and a covering film, wherein the covering film covers the aluminum circuit layer and is combined with the dielectric layer, the aluminum circuit layer comprises an electrical connection pad, and the electrical connection pad is exposed from the covering film; forming a copper plating layer on the electrical connection pad of the circuit substrate exposed from the covering film; and forming a nickel plating layer on the copper plating layer.

[0005] In the above-mentioned circuit board processing process of the present application, a copper plating layer is formed on the aluminum electrical connection pad before forming the nickel plating layer to prevent the aluminum electrical connection pad from reacting with the reaction liquid in the reaction tank to produce dissolution during nickel plating, and at the same time avoids using a zinc layer to cover the aluminum electrical connection pad, which is beneficial to avoid uneven color, brittleness, and even pinholes when the nickel plating layer is subsequently formed, which affects the quality of the nickel plating layer, and is also beneficial to prolonging the service life of the mixed solution during nickel plating, that is, the chemical nickel plating tank.

[0006] Based on the first aspect, in a possible implementation, the forming of the copper plating layer includes: placing the circuit substrate in a copper sulfate solution at 25° C. to 40° C. to deposit a 2 μm to 4 μm copper plating layer on the electrical connection pads exposed from the cover film.

[0007] In the possible implementation manners described above, the formation of the copper plating layer facilitates effectively covering the electrical connection pads 130 while controlling costs.

[0008] Based on the first aspect, in a possible implementation, the formation of the nickel plating layer includes: placing the circuit substrate with the copper plating layer in a mixed solution of nickel sulfate and sodium dihydrogen hypophosphite at 80°C to 90°C and soaking it for 6min to 15min to form a nickel plating layer of 3 microns to 6 microns, wherein in the mixed solution, the concentration of the nickel sulfate is 4.5g / L to 5.5g / L, and the concentration of the sodium dihydrogen hypophosphite is 20g / L to 30g / L.

[0009] Based on the first aspect, in a possible implementation, before forming the copper plating layer, the method further includes: cleaning and roughening the electrical connection pads of the circuit substrate exposed from the cover film.

[0010] In the above possible implementation manner, the cleaning and roughening treatment facilitates improving the bonding force between the subsequent copper plating layer and the electrical connection pad.

[0011] Based on the first aspect, in a possible implementation, before forming the nickel plating layer, it also includes: roughening the copper plating layer, wherein the surface roughness of the copper plating layer after the roughening treatment is greater than or equal to 0.2 microns.

[0012] In the above possible implementation manner, the roughening treatment facilitates improving the bonding strength between the subsequent nickel plating layer and the copper plating layer.

[0013] Based on the first aspect, in a possible implementation, before forming the nickel plating layer, it also includes: immersing the circuit substrate with the copper plating layer in a mixture of sulfuric acid and palladium sulfate at 25°C to 30°C for 30 seconds to 90 seconds to form a palladium layer, wherein the concentration of the sulfuric acid is 3% to 8%, and the concentration of the palladium sulfate is 5ppm to 20ppm.

[0014] In the above possible implementation manner, the formation of the palladium layer can serve as a catalyst for the subsequent formation of the nickel plating layer, thereby facilitating the improvement of efficiency.

[0015] Based on the first aspect, in a possible implementation, before forming the nickel plating layer, the method further includes: immersing the copper plating layer in sulfuric acid with a concentration of 5% to 10% at room temperature.

[0016] In the above possible implementation manner, the above operation can remove the oxide layer on the surface of the copper plating layer, thereby facilitating improving the bonding strength between the subsequent nickel plating layer and the copper plating layer.

[0017] Based on the first aspect, a possible implementation manner further includes: performing a gold treatment on the electrical connection pad to form a gold plating layer covering the nickel plating layer.

[0018] The second aspect of the present application provides a circuit board, comprising a circuit substrate, a copper plating layer and a nickel plating layer. The circuit substrate comprises a dielectric layer, an aluminum circuit layer arranged on one side of the dielectric layer and a covering film, wherein the covering film covers the aluminum circuit layer and is combined with the dielectric layer. The aluminum circuit layer comprises an electrical connection pad, and the electrical connection pad is exposed from the covering film, the copper plating layer is arranged on the electrical connection pad exposed from the covering film, and the nickel plating layer covers the copper plating layer. The electrical connection pad of the above-mentioned circuit board is conducive to reducing the risk of welding failure when welding with external electronic components.

[0019] The second aspect of the present application provides a battery module, comprising a cell module and a circuit board as described above, wherein the circuit board is electrically connected to a bus bar of the cell module through the nickel plating layer. In the battery module, the electrical connection pads of the circuit board are helpful in reducing the risk of welding failure when welding with the bus bar or an external electronic component. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A flowchart of a circuit board processing process according to an embodiment of the present application.

[0021] Figure 2 A schematic cross-sectional view of a circuit substrate according to an embodiment of the present application.

[0022] Figure 3 For Figure 2 A schematic cross-sectional view of a copper plating layer formed on a circuit substrate is shown.

[0023] Figure 4 For Figure 3 A schematic cross-sectional view of a nickel plating layer formed on a copper plating layer is shown.

[0024] Figure 5 For Figure 3 The cross-sectional schematic diagram of a palladium layer and a nickel plating layer being formed sequentially on the copper plating layer is shown.

[0025] Figure 6 For Figure 4 Schematic diagram of a cross section of a gold plating layer formed on a nickel plating layer.

[0026] Figure 7 A schematic cross-sectional view of a circuit board according to an embodiment of the present application.

[0027] Main component symbols

[0028] Circuit board 10 Dielectric layer 11 Aluminum circuit layer 13 Covering film 15 Electrical connection pads 130 First electrical connection pad 130a Second electrical connection pad 130b Copper plating 30 Nickel plating 50 Palladium layer 40 Gold plating 60 Circuit Board 100

[0029] The following specific implementation methods will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] 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 this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0032] Some embodiments of the present application are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0033] See also Figure 1 The present application provides a circuit board processing process according to an embodiment of the present invention, which comprises the following steps:

[0034] Step S1, see Figure 2 A circuit substrate 10 is provided, comprising a dielectric layer 11, an aluminum circuit layer 13 disposed on one side of the dielectric layer 11, and a cover film 15. The cover film 15 covers the aluminum circuit layer 13 and is combined with the dielectric layer 11. The aluminum circuit layer 13 comprises an electrical connection pad 130, and the electrical connection pad 130 is exposed from the cover film 15.

[0035] In some embodiments, the electrical connection pad 130 may include a first electrical connection pad 130a and a second electrical connection pad 130b, wherein the first electrical connection pad 130a and the second electrical connection pad 130b are respectively used for subsequent electrical connection of different electronic components. The second electrical connection pad 130b may be an exposed pad.

[0036] Step S2, see Figure 3 A copper plating layer 30 is formed on the electrical connection pads 130 of the circuit substrate 10 exposed from the cover film 15 .

[0037] In this embodiment, the copper plating layer 30 can be prepared by, but not limited to, the following method: placing the circuit substrate 10 in a copper sulfate solution for a replacement reaction, thereby depositing and forming the copper plating layer 30 on the electrical connection pads 130 exposed from the cover film 15 .

[0038] Specifically, in this embodiment, the temperature of the replacement reaction may be 25° C. to 40° C. The thickness of the copper plating layer 30 may be 2 μm to 4 μm, so as to effectively cover the electrical connection pad 130 while controlling the cost.

[0039] In some embodiments, before placing the circuit substrate 10 in a copper sulfate solution for reaction, the method may further include: cleaning the circuit substrate 10 .

[0040] Specifically, the cleaning of the circuit substrate 10 may include but is not limited to at least one of degreasing and water washing. Degreasing is a commonly used method in the industry, for example but not limited to using an organic acid or alkaline solution with a surfactant added to remove grease in the circuit substrate and oxides on the aluminum circuit layer 13. The number of water washings may be multiple times, and the water washing method may include but is not limited to at least one of immersion, showering, ultrasonic waves, etc.

[0041] In some embodiments, before placing the circuit substrate 10 in a copper sulfate solution for reaction, a step may also be included: roughening the electrical connection pads 130 of the circuit substrate 10 exposed from the covering film 15, thereby improving the bonding strength between the electrical connection pads 130 and the subsequent copper plating layer 30.

[0042] The roughening treatment may specifically include but is not limited to: soaking or spraying the electrical connection pad 130 with 1wt% to 5wt% sodium hydroxide solution or 1wt% to 5wt% potassium hydroxide solution at a temperature of 25° C. to 35° C. In this embodiment, the roughness of the electrical connection pad 130 may be 0.2 micrometers to 0.5 micrometers.

[0043] Step S3, see Figure 4 , a nickel plating layer 50 is formed on the copper plating layer 30 .

[0044] In this embodiment, the nickel plating layer 50 may be formed by, but is not limited to, the following method: immersing the circuit substrate 10 with the copper plating layer 30 in a mixed solution of nickel sulfate and sodium dihydrogen hypophosphite to form the nickel plating layer 50 .

[0045] Specifically, in the present embodiment, the nickel plating layer 50 can be formed by soaking in a mixed solution at 80°C to 90°C for 6min to 15min. Wherein, in the mixed solution, the concentration of the nickel sulfate can be 4.5g / L to 5.5g / L, and the concentration of the sodium dihydrogen hypophosphite can be 20g / L to 30g / L. The thickness of the nickel plating layer 50 can be 3 microns to 6 microns, so as to have good welding strength and corrosion resistance. Forming the nickel plating layer 50 at the above temperature can maintain a good deposition rate of the nickel layer (approximately 0.2 microns / min to 1 micron / min), which is conducive to forming a uniform, continuous and good quality nickel plating layer 50.

[0046] In some embodiments, before forming the nickel plating layer 50, the step of roughening the copper plating layer 30 may be further included to enhance the bonding force between the subsequently formed nickel plating layer 50 and the copper plating layer 30. The surface roughness of the copper plating layer 30 after the roughening treatment may be greater than or equal to 0.2 microns.

[0047] For further information, please refer to Figure 5 Before forming the nickel plating layer 50, the method may further include the step of activating the copper plating layer 30 to form a palladium layer 40 as a catalyst for the subsequent formation of the nickel plating layer 50. The step of forming the palladium layer 40 may be performed before or after the roughening treatment.

[0048] The palladium layer 40 may be formed by, but is not limited to, the following method: immersing the circuit substrate 10 with the copper plating layer 30 in a mixed solution of sulfuric acid and palladium sulfate.

[0049] Specifically, the palladium layer 40 can be formed by immersing in a mixed solution at 25° C. to 30° C. for 30 seconds to 90 seconds. In the mixed solution, the volume percentage of sulfuric acid can be 3% to 8%, and the concentration of palladium sulfate can be 5 ppm to 20 ppm.

[0050] In some embodiments, before forming the nickel plating layer 50 , a step may be further included: performing an acid treatment on the copper plating layer 30 to remove an oxide layer on the surface.

[0051] The acidification treatment can be achieved by, but is not limited to, the following method: immersing the copper plating layer 30 in sulfuric acid. Specifically, the temperature of the acidification treatment can be room temperature, the concentration of sulfuric acid in the acidification treatment can be 5% to 10% (volume percentage), and the acidification treatment time can be 15 seconds to 45 seconds.

[0052] It is understandable that each of the above steps may be washed with water before and after to avoid contamination of subsequent reactions or residues causing excessive reactions.

[0053] In this embodiment, the circuit board processing process may further include: step S4, see Figure 6 , the first electrical connection pad 130 a is subjected to a gold plating treatment to form a gold plating layer 60 covering the nickel plating layer 50 .

[0054] The thickness of the gold plating layer 60 may be 0.01 micrometer to 0.05 micrometer.

[0055] In some embodiments, during the gold treatment, a gold plating layer 60 may be formed on the nickel plating layer 50 on the second electrical connection pad 130 b at the same time.

[0056] See also Figure 7 The present application also provides a circuit board 100, comprising a circuit substrate 10, a copper plating layer 30 and a nickel plating layer 50. The circuit substrate 10 comprises a dielectric layer 11, an aluminum circuit layer 13 disposed on one side of the dielectric layer 11, and a covering film 15, wherein the covering film 15 covers the aluminum circuit layer 13 and is combined with the dielectric layer 11. The aluminum circuit layer 13 comprises an electrical connection pad 130, and the electrical connection pad 130 is exposed from the covering film 15. The copper plating layer 30 is disposed on the electrical connection pad 130 exposed from the covering film 15, and the nickel plating layer 50 covers the copper plating layer 30.

[0057] The copper plating layer 30 may have a thickness of 2 micrometers to 4 micrometers, so as to effectively cover the electrical connection pads 130 while controlling the cost.

[0058] The thickness of the nickel plating layer 50 may be 3 micrometers to 6 micrometers.

[0059] In some embodiments, a palladium layer 40 is further disposed between the copper plating layer 30 and the nickel plating layer 50 .

[0060] In some embodiments, the circuit board 100 may further include a gold plating layer 60, and the gold plating layer 60 is disposed on a surface of the nickel plating layer 50 away from the copper plating layer 30. The thickness of the gold plating layer 60 may be 0.01 micrometer to 0.05 micrometer.

[0061] The electrical connection pad 130 may include a first electrical connection pad 130a and a second electrical connection pad 130b, wherein the first electrical connection pad 130a and the second electrical connection pad 130b are respectively used for subsequent electrical connection of different electronic components. The second electrical connection pad 130b may be an exposed pad. The gold plating layer 60 may be formed only on the first electrical connection pad 130a.

[0062] The present application also provides a battery module (not shown), including a battery cell module (not shown) and the above-mentioned circuit board 100, wherein the electrical connection pad 130 of the circuit board 100 is electrically connected to the bus (not shown) of the battery cell module (not shown) through the nickel plating layer 50.

[0063] In the above-mentioned circuit board processing process of the present application, a copper plating layer 30 is formed on the aluminum electrical connection pad 130 before forming the nickel plating layer 50, so as to prevent the aluminum electrical connection pad 130 from reacting with the reaction liquid in the reaction tank to dissolve during nickel plating, and avoid using the zinc layer to cover the aluminum electrical connection pad 130, which is beneficial to avoid the occurrence of uneven color, brittleness, and even pinholes when the nickel plating layer 50 is subsequently formed, which affects the quality of the nickel plating layer 50, and is also beneficial to prolonging the service life of the mixed solution during nickel plating, that is, the chemical nickel plating tank. The circuit board obtained by the above-mentioned circuit board processing process is beneficial to reduce the risk of welding failure when welding with other electronic components.

[0064] The above is only the preferred implementation mode of the present application, and is not any form of limitation on the present application. Although the present application has been disclosed as the preferred implementation mode as above, it is not used to limit the present application. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent implementation modes without departing from the scope of the technical solution of the present application. However, any simple modification, equivalent change and modification made to the above implementation modes based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A circuit board processing process, wherein: The following steps are involved: A circuit substrate is provided, comprising a dielectric layer, an aluminum circuit layer disposed on one side of the dielectric layer, and a covering film, wherein the covering film covers the aluminum circuit layer and is combined with the dielectric layer, the aluminum circuit layer comprises an electrical connection pad, and the electrical connection pad is exposed from the covering film; forming a copper plating layer on the electrical connection pads of the circuit substrate exposed from the cover film; as well as A nickel plated layer is formed on the copper plated layer.

2. The circuit board processing process according to claim 1, characterized in that: The formation of the copper plating layer comprises: The circuit substrate is placed in a copper sulfate solution at 25° C. to 40° C. to deposit a copper plating layer of 2 μm to 4 μm on the electrical connection pads exposed from the cover film.

3. The circuit board processing process according to claim 1, characterized in that: The formation of the nickel plating layer comprises: The circuit substrate with the copper plating layer is immersed in a mixed solution of nickel sulfate and sodium dihydrogen hypophosphite at 80° C. to 90° C. for 6 min to 15 min to form a nickel plating layer of 3 μm to 6 μm, wherein in the mixed solution, the concentration of the nickel sulfate is 4.5 g / L to 5.5 g / L, and the concentration of the sodium dihydrogen hypophosphite is 20 g / L to 30 g / L.

4. The circuit board processing process according to claim 1, characterized in that: Before forming the copper plating layer, the method further comprises: The electrical connection pads of the circuit substrate exposed from the cover film are cleaned and roughened.

5. The circuit board processing process according to claim 1, characterized in that: Before forming the nickel plating layer, the method further comprises: The copper plating layer is subjected to a roughening treatment, wherein the surface roughness of the copper plating layer after the roughening treatment is greater than or equal to 0.2 micrometers.

6. The circuit board processing process according to claim 1, characterized in that: Before forming the nickel plating layer, the method further comprises: The circuit substrate with the copper plating layer is immersed in a mixed solution of sulfuric acid and palladium sulfate at 25° C. to 30° C. for 30 seconds to 90 seconds to form a palladium layer, wherein the concentration of the sulfuric acid is 3% to 8%, and the concentration of the palladium sulfate is 5 ppm to 20 ppm.

7. The circuit board processing process according to claim 1, characterized in that: Before forming the nickel plating layer, the method further comprises: The copper plating layer is immersed in sulfuric acid with a concentration of 5% to 10% at room temperature.

8. The circuit board processing process according to claim 1, characterized in that: Also includes: The electrical connection pad is subjected to a gold plating treatment to form a gold plating layer covering the nickel plating layer.

9. A circuit board, characterized in that: The invention comprises a circuit substrate, a copper plating layer and a nickel plating layer, wherein the circuit substrate comprises a dielectric layer, an aluminum circuit layer arranged on one side of the dielectric layer and a covering film, wherein the covering film covers the aluminum circuit layer and is combined with the dielectric layer, the aluminum circuit layer comprises an electrical connection pad, and the electrical connection pad is exposed from the covering film, the copper plating layer is arranged on the electrical connection pad exposed from the covering film, and the nickel plating layer covers the copper plating layer.

10. A battery module, characterized in that: It comprises a battery cell module and the circuit board as claimed in claim 9, wherein the circuit board is electrically connected to the busbar of the battery cell module through the nickel plating layer.

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