Home ›

Mild Acceleration Factors

Idea/Definition Information
Background: 
  • Current testing (industry and consortium) of Pb-free assemblies in accelerated conditions (0-100C, -40 to +125C, etc.) shows significant reductions in solder joint reliability (SAC reliability <<SnPb) for certain component types (high strain components).  These components are used on the majority of high reliability products.  There are no accepted acceleration factors or models for SAC reliability that relate accelerated conditions to field conditions.
  • The data available also indicates that SAC reliability ≥ SnPb for low strain components.
  • Aging factors affecting microstructure, creep and fatigue on SAC alloys have only recently been identified.
  • Strain ∞ DNP x ΔCTE x ΔT
Problem: 

Determine if highly accelerated test conditions are introducing failure "modes" that don't exist in field (milder) conditions.

Approach: 

Reduce the ΔT and perform a mildly accelerated temperature cycle after appropriate preconditioning to test the hypothesis.  SnPb products otherwise identical are used as the control/baseline.