Will PI tin plated film crack or break during bending or folding? How to improve?

Brief introduction

Polyimide film (PI film) is widely used in electronic products such as flexible circuit boards (FPC) and copper-clad laminates due to its unique properties. To improve its conductivity, a layer of metal such as tin is usually deposited on the PI film. However,PI tin plated filmCracks or fractures may occur during the bending or folding process, which directly affects its service life and reliability.

2、 Experimental Design and Methods

experimental materials

This study usedAdvanced Institute (Shenzhen) Technology Co., LtdProvidedPI Tin Plating Film SampleThe film thickness is 25 μ m, and the tin plating layer thickness is 2 μ m.

Experimental device

• Bending test: Perform bending test using a universal material testing machine (Instron 5566).
• Folding test: Use specially designed folding equipment to simulate the folding situation in actual use.

experimental procedure

1. Bending test: Fix the PI tin plated film on the universal material testing machine and perform cyclic bending test with a bending radius of R=1mm and a test frequency of 1000 times.
2. Folding test: Install the PI tin plated film on the folding device and conduct a cyclic folding test with a folding angle of 180 ° and a test frequency of 1000 times.

3、 Experimental results and analysis

data comparison

4、 Cause analysis

The main reasons for cracks or fractures in PI tin plated film during bending or folding may include:

1. Insufficient ductility of the coating: Tin coatings are prone to cracking under repeated stress.
2. Poor adhesion between substrate and coating: During bending or folding, delamination may occur between the substrate and coating.
3. Stress concentration: Stress concentration occurs at the sharp corners of bending or folding, leading to the occurrence of cracks.

5、 Improvement measures

To improve the performance of PI tin plated film during bending or folding, the following measures can be taken:

1. Use nanoscale coatings

Research has shown that inPI tin plated filmCoating the surface with a nanoscale protective coating can significantly improve its ductility and crack resistance. A nano silicon coating developed by Advanced Institute (Shenzhen) Technology Co., Ltd. has been tested and found to maintain a high fracture force (47N) and no cracks in the PI tin plated film after 1000 bending cycles.

2. Optimize the plating process

• Improve the uniformity of the coating: Ensure the uniform distribution of the coating on the PI film and avoid stress concentration caused by local thickness differences.
• Enhance the adhesion between the substrate and the coating: By improving the pre-treatment process before the coating, such as plasma treatment or chemical modification, the bonding strength between the coating and the substrate can be improved.

3. Using composite materials

• Composite coating: Adding a layer of other metal or alloy, such as copper tin alloy, on top of the tin coating to improve the overall ductility and fatigue resistance.
• Multi layer structure design: Adopting a multi-layer structure design, such as PI/copper/tin/PI, can disperse stress and reduce the occurrence of cracks.

6、 Conclusion

By comparingPI tin plated filmIn the study of performance analysis and improvement measures during bending or folding processes, we found that by using nanoscale coatings, optimizing coating processes, and adopting composite materials, the ductility and crack resistance of PI tin plated films can be effectively improved. These improvement measures can not only meet the needs of applications such as flexible circuit boards (FPCs), but also expand the application prospects of PI tin plated films in more fields.
The above data is for reference only, and specific performance may vary due to production processes and product specifications.