Fracture through intermetallic voids after one year 'on the shelf' at rom temperature.

What? Most solders bond to Cu by forming a Cu₆Sn₅ intermetallic layer on top of a very thin Cu₃Sn layer. Both layers grow with time after assembly, and often a few voids form within the Cu₃Sn. Occasionally, voiding may be severe enough to weaken the joint (links). If that hasn't happened to you yet, you have simply been lucky. More...

You don't use SnAgCu? Voiding is equally severe with SnAg and eutectic SnPb.

Your service conditions are mild? The worst we have seen led to weak joints within less than 1000 hours at 38°C (98°F) or one year at room temperature (see image above).

How great is your risk? The problem is commonly underestimated: Roughly 10% of all Cu surveyed showed cause for concern, the problem is highly variable (even from 'quality suppliers'), and accelerated tests may be dangerously misleading. More...

• What can you do? Click here for suggestions.

Questions/Comments? Email us at borgesen@uic.com