Pushing the Envelope in DFM
Prepared by Colin Koh, Paul Gunn, Muhammad Syafiq, Takuto Yoshida
Presented at BiTS Workshop, Arizona March 15 -18, 2015 & BiTS Workshop, Shanghai on October 21, 2015
Contents
- Socket 1 Design
- Improved Socket 2 Design
- First FEA Simulation for Socket 2
- FEA Simulation Improvement
- Compare FEA Simulation and Actual Measurement
- Improved Socket 3 Design
- FEA Simulation Improvement
- Compare FEA Simulation and Actual Measurement
- Conclusion
Socket 1
- Total 1656 pins for 6 devices
- 1 Top Plate (TP) Design
- Socket side 6x M3 screws to keep TP coplanar at pin areas
- Without FEA
Coplanarity Measurement
- Target 0.050mm for coplanarity
- Max. 0.116mm coplanarity from measurement
- Warpage trend shows at center area
- TP hardness is not enough
- Tight screws is far from pin areas
- FEA is required for next design
Improved Socket 1 Simulation & Measurement
- Max. 0.129mm coplanarity from improved simulation
- Max. 0.116mm coplanarity from measurement
Compare Socket 1 Simulation and Actual Measurement
- Coplanarity error rate is 20% or less
Socket 2
- Total 2370 pins for 6 devices
- Improvements
- Stainless Steel Holder & Ceramic Peek TP
- 12x TP screws closer to pin area
- Design with FEA simulation
First FEA Simulation for Socket 2
- Coplanarity values are different in nominal and worst case
- We estimated actual coplanarity close to nominal case
Socket 2 Coplanarity Measurement
- Target 0.050mm for coplanarity
- Max. 0.125mm coplanarity from measurement
- Coplanarity measurement close to worst case
- Need to improve the FEA
FEA Simulation Improvement
- Implement elastic membrane technique
- To predict deformation
- To predict stress values
- Elastic membrane technique provides
- More stiffness reliability
- More robust design
- Refer to Prabakaranand Pal, Finite Element Analysis using Elastic Membrane Technique for Test Socket Design Optimization (BiTS, 2008)
Improved Socket 2 Simulation & Measurement
- Max. 0.116mm coplanarity from improved simulation
- Max. 0.125mm coplanarity from measurement
Compare Socket 2 Simulation and Actual Measurement
- Coplanarity error rate is 19% or less
Socket 3
- Total 2430 pins for 6 devices
- Change TP material to Machinable Ceramic
- Target 0.050mm for coplanarity
- Max. 0.019mm coplanarity from improved simulation
Improved Socket 3 Simulation & Measurement
- Max. 0.019mm coplanarity from improved simulation
- Max. 0.023mm coplanarity from measurement
Compare Socket 3 Simulation and Actual Measurement
- Coplanarity error rate is 21% or less
Conclusion
- FEA simulation using Elastic Membrane technique proves good DFM relationship between design to actual socket
- FEA provides more robust design and stiffness to enhance product reliability
Reference
Prabakaranand Pal, 2008, Finite Element Analysis using Elastic Membrane Technique for Test Socket Design Optimization, Burn-In and Test Socket Workshop, Hot Topics Session
