Technical Paper

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)
  • 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.