Lead-free BGA shock

The electronic manufacturing industry as a whole has gotten much more comfortable with lead-free processing over the last six months. We've been offering RoHS processing for a year and a half now. Still, there are some challenges in areas such as longevity and shock performance.

We tend to deal primarily with prototypes so some of the challenges are less of an issue for our customers at our stage in the NPI process then for later stages. One such issue is that of lead-free BGA shock resistance with SAC (Tin, Silver, Copper) solder. One of the solutions being explored by the industry is an adhesive underfill.

I ran across this article by Jim Hisert of Indium Corporation that covers two different methodologies. Again, we don't perform underfill here, but when you get to production, if you have a high-stress application with lead-free BGAs, you might want to consider it as an option with your production assembly house.

Duane Benson

Comments

[Jim Hisert]

I'm partial to using underfill to increase shock reliability - but new Pb-Free alloys are being introduced (beyond SAC105) which will offer better drop test performance than Sn/Pb. These alloys need to have some time in production to fully understand the effects of a new metalurgy, but I think you'll start seeing more about them soon. Right now I see a lot of people using no-flow underfill because it is a relatively simple drop-in for assemblers who do not have experience or are not set up for capillary underfill. The process advantages make it attractive also.

[Jeremy Pearce]

Maybe you already have this, but some data from last year has shown that SAC 105 (Intel) or SAC 101 (Philips) with Ni doping can improve shock performance for BGA's.

See:

http://digbig.com/4rtky

and

http://digbig.com/4hnks

Jeremy Pearce
ELFNET Coordinator