Solder Migration DoE for Pin
Prepared by Lai Chen Yong
Presented at BiTS Workshop on March 6 – 9, 2011
Objective
DoE on different pin tip material and plating to address the solder migration issue.
DoE Set Up
- BGA pin type’s details.
- 6 types of pins are populated in one test contactor.
- Using BGA mechanical package for cycling test.


Lab Data
Variability Chart (0‐15k)Lab Data
Variability Chart (20‐50k)Lab Data
Variability Chart (60‐100k)Lab Data
Variability Chart (300‐500k)
Variability Chart (0‐15k)Lab Data
Variability Chart (20‐50k)Lab Data
Variability Chart (60‐100k)Lab Data
Variability Chart (300‐500k)
- Up to 15k, Type 5 pin lowest CRES mean & stdev.
- Type 4 pin shown the highest CRES mean & stdev after 15k
- Best to worst : T5 ‐> T1/T2/T3/T6 ‐> T4
Type 1: BeCu/PdCo
Type 2: SK4/AuNi
Type 3: BeCu/AuNi/Nano
Type 4: Paliney7
Type 5: BeCu/AuNi
Type 6: SK4/PdCo

- From 20‐50k, Type 1, 2 & 5 pin with lowest CRES mean & stdev.
- Type 4 & 6 pin shown the highest CRES mean & stdev.
- Best to worst : T1/T2/T5 ‐> T3 ‐> T4/T6
Type 1: BeCu/PdCo
Type 2: SK4/AuNi
Type 3: BeCu/AuNi/Nano
Type 4: Paliney7
Type 5: BeCu/AuNi
Type 6: SK4/PdCo

- From 60‐100k, Type 1 & 2 pin with lowest CRES mean.
- Best to worst: T1/T2 ‐> T3/T5/T6 ‐> T4
Type 1: BeCu/PdCo
Type 2: SK4/AuNi
Type 3: BeCu/AuNi/Nano
Type 4: Paliney7
Type 5: BeCu/AuNi
Type 6: SK4/PdCo

- Type 1 & 2 still show the lowest mean & smaller spread among all.
Type 1: BeCu/PdCo
Type 2: SK4/AuNi
Type 3: BeCu/AuNi/Nano
Type 4: Paliney7
Type 5: BeCu/AuNi
Type 6: SK4/PdCo

Conclusion
- Type 5 (BeCu/AuNi) pin tip didn’t show major impact on the solder migration issue as it works normally after the brushing process.
- Type 1 (BeCu/PdCo) & type 2 (SK4/AuNi) pin showed lower mean CRES up to 500k cycles, and was consistent along all the test intervals from the DoE.
- Pin’s CRES is able to reduce to acceptable region after the brushing process in all cycle intervals regardless of the pin type in different material and plating.