related document
quality & reliability
Solder Joint Interface Study
Interfaces of the Solder Joints after TC 1k cycles
Sample Preparation
The boards used
- Layer: 6 layers
-
Land finish materials
Ni(min. 0.5um)/Au(0.05~0.3um)
PSR open size: Pad size + 300um
- Package type: 54TSOP
- Lead finish: SnBi ( composition: 3 ~ 5%Bi, thickness: avg. 15 um)
- SnPb Solder: 63/37 SnPb eutectic solder
- Pb-free Solder: Sn3.0Ag0.5Cu solder
-
Temperature Range: -25 ~ 125 °C
30 minutes/cycle(JEDEC conditon) - 48 cycles/day
( Severe condition compared to the current specification, 0 ~ 125 °C)
The following data were from the real working memory modules.
SnBi and SnPb Joint
The SnBi finished components with SnPb solder -> No Drastic Phase Transformation!!
EDS Mapping of the Interface after TC1k cycles
Can't detect the Bi which diffuse into the solder!!!
(Bi concentration in the electrodeposit is too low to detect compared with total volume of the joint)
SnBi and SnAgCu Joint
The SnBi finished components with SnPb solder -> No Drastic Phase Transformation!!
EDS Mapping of the Interface after TC1k cycles
Can't detect the Bi which diffuse into the solder!!!
(Bi concentration in the electrodeposit is too low to detect compared with total volume of the joint)
