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Method for manufacturing flexible circuit board

A technology for flexible circuit boards and manufacturing methods, which is applied to the reinforcement of conductive patterns and the secondary treatment of printed circuits, etc., can solve the problems of long soldering time, difficult process control, and high difficulty, and achieve the reduction of tin whiskers. Easy to operate and prevent mutual diffusion effect

Inactive Publication Date: 2011-01-12
XIAMEN DIAL ELECTRONICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But this process is difficult to control, the difficulty is large, the operable range is small, and the copper content in the coating is difficult to control
2. A layer of tin is chemically plated on the bare copper of the flexible circuit board (called: chemical immersion tin), which can improve tin whiskers or even prevent tin whiskers, but now the thickness of chemical immersion tin is generally 0.5- 1.5 microns, so the corrosion resistance is poor, and the welding time is long, so it cannot be applied to the protection of the socket

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] A method for manufacturing a flexible circuit board, comprising the steps of:

[0018] 1. Degreasing: Put the flexible circuit board into a container containing an acidic degreaser with a concentration of 15% (V / V), and soak for 5 minutes at a temperature of 30°C;

[0019] 2. Washing: wash off the dirt and liquid medicine on the surface of the flexible circuit board;

[0020] 3. Micro-etching: Soak the flexible circuit board in a tank filled with a micro-etching solution mixed with sodium persulfate, sulfuric acid and water. The sodium persulfate is 80 g / L, and the sulfuric acid is 3% (V / V) , the temperature of the microetching solution is 20°C, and the soaking time is 30 seconds;

[0021] 4. Pickling: soak the flexible circuit board in a container filled with 5% methanesulfonic acid solution for 1 minute;

[0022] 5. Chemical immersion tin: soak the flexible circuit board in a container containing immersion tin potion. The temperature of the immersion tin potion is 5...

Embodiment 2

[0032] A method for manufacturing a flexible circuit board, comprising the steps of:

[0033] 1. Degreasing: put the flexible circuit board into a container containing an acidic degreasing agent with a concentration of 10% (V / V), the temperature of the solution is 40°C, and soak for 5 minutes;

[0034] 2. Washing: wash off the dirt and liquid medicine on the surface of the flexible circuit board;

[0035] 3. Micro-etching: Soak the flexible circuit board in a tank filled with a micro-etching solution mixed with sodium persulfate, sulfuric acid and water. The sodium persulfate is 50 g / L, and the sulfuric acid is 2% (V / V) , the temperature of the microetching solution is 30°C, and the soaking time is 90 seconds;

[0036] 4. Pickling: soak the flexible circuit board in a container filled with 10% methanesulfonic acid solution for 2 minutes;

[0037] 5. Chemical immersion tin: Soak the flexible circuit board in a container with immersion tin potion. The temperature of the immers...

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PUM

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Abstract

The invention discloses a method for manufacturing a flexible circuit board, which comprises processes of oil removal, washing, micro etching, acid dipping, tinning and drying of the flexible circuit board. The method is characterized in that: after the acid dipping of the flexible circuit board and before tinning, chemical tin deposition is performed. Because the chemical tin deposition is performed before tinning, a chemical tin deposition layer serving as a barrier layer is increased between the copper of the flexible circuit board and the tin of the plating layer so as to effectively prevent mutual diffusion of the copper of the flexible circuit board and the tin of the tinning layer and reduce the generation of tin whiskers without changing the properties and purposes of the flexible circuit board; and the method is convenient in process operation, simple, reliable and easy to control.

Description

technical field [0001] The invention relates to a method for manufacturing a flexible circuit board, in particular to a method for manufacturing a flexible circuit board capable of reducing tin whiskers. Background technique [0002] Flexible circuit boards are widely used. Usually, a layer of tin is plated on the exposed copper surface of the flexible circuit board with a thickness of 5-15 microns to protect the copper surface from oxidation and improve solderability. The tin plating process is simple, easy to control, low in price, good in solderability, in line with environmental protection requirements, and widely used in circuit boards. However, after tin plating, tin and copper diffuse each other to form intermetallic compounds, and the internal compressive stress of the tin layer increases rapidly, causing tin atoms to diffuse along the crystal boundaries, forming tin whiskers, and causing short circuits. With the increase of circuit board density, the distance betw...

Claims

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Application Information

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IPC IPC(8): H05K3/22H05K3/24
Inventor 张利
Owner XIAMEN DIAL ELECTRONICS
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