Whiskers were an early problem, but the biggest issues right now are: - Lead-free solders don't wet/flow as well as leaded, which causes lower manufacturing yi

Whiskers were an early problem, but the biggest issues right now are: - Lead-free solders don't wet/flow as well as leaded, which causes lower manufacturing yields. - Lead-free solders are generally more brittle and subject to earlier fatigue failures than leaded solders, so the lead-free units often fail prematurely (compared to leaded ones).