Numerical Study on New Pin Pull Test for Pad Cratering
In this study a new pin pull test method with solder ball attached and positioned to the test board at a 30° was used to study the strength of pad cratering.
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Authored By:
Billy Hu
Flextronics, Shenzhen, China
Jesus Tan
Flextronics, Guangdong, China
Summary
Pad cratering is an important failure mode besides crack of solder joint as it'll pass the regular test but have impact on the long term reliability of the product. A new pin pull test method with solder ball attached and positioning the test board at an angle of 30° is employed to study the strength of pad cratering. This new method clearly reveals the failure mechanism. And a proper way to interpret the finite element analysis (FEA) result is discussed. Impact of pad dimension, width and angle of copper trace on the strength is included. Some findings not included in previous research could help to guide the design for better performance.
Conclusions
FEA research on the pin pull test with the test board positioning at an angle of 30° is conducted in this paper. The strength of pad cratering will increase as the pad diameter increases. The copper trace will strengthen the PCB and bigger width is better.
Comparison of different angle of copper trace shows that 45° is best choice. Anyway the numerical study is based on the model and material properties introduced. The findings will be validated with test in future work.
Initially Published in the IPC Proceedings
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