# Tag Archives: Weibull distribution

## Weibull Part III

Folks, Our discussion of Weibull Analysis continues…. Let’s say you have worked hard and assembled some SMT lead-free PCBs for thermal cycle testing. You used the best lead-free solder paste and some lead-free solder preforms as you assembled several through-hole … Continue reading

## Weibull Analysis II: The Curse of the Early First Failure

Folks, In continuing our discussion on Weibull Analysis, let’s assume we assembled some SMT and through-hole PCBs with lead-free solder paste. On this board are also some bottom-side terminated (BTC) components (often called QFNs), that are also assembled with solder … Continue reading

## Interpreting Weibull Plots: I

Folks, A while ago I discussed the Weibull Distribution and its importance in electronics reliability analysis. This distribution has been used to evaluate the life of solder joints whether formed in SMT, wave, or even using solder preforms. In the … Continue reading

## Can Your Mortality be Modeled with Weibull Distribution?

Folks, In the last posting we saw how Weibull analysis helped us to determine that SACM lead-free solder (SAC 105 with about 0.1% manganese) has comparable (actually better) thermal cycle performance versus SAC 305 solder. Software like Minitab will give … Continue reading

## Weibull Analysis of Solder Joint Failure Data II

Folks, Last time we introduced Weibull analysis. Let’s derive the relationships needed to calculate the slope, beta, and characteristic life, eta. F(t) is the cumulative fraction of fails, from 0 to 1. By choosing Ln(t) as x and LnLn … Continue reading