Soldering LGA parts
LGA (Land Grid Array) packaged parts are most commonly found on socketed processors in personal computers. It's not that different a package than a BGA (Ball Grid Array) except of course there are no solder balls on the part.
We've started getting a few requests to solder on LGA parts and I expect that we will be seeing more and more as time goes on. The BGA, of course, is a very well known and well used part. The package does have a few disadvantages though:
- Sometime the balls will fall off with handling or transport
- You have to source either leaded or lead-free versions to match the rest of your board - RoHS board, use lead-free BGAs; non-RoHS board, use BGAs with leaded balls.
LGA parts don't have any solder on them prior to assembly, so you can use the same part (provided it meets the RoHS heat requirements) for RoHS and non-RoHS assemblies. Of course, you also don't have to worry about missing balls. Further, the part will have a lower profile once assembled which may be better for heat sink mounting or small form-factor applications.
The important considerations are, again, very similar to those of BGA parts. The stencil aperture must be carefully considered and NSMD (Non-Solder Mask Defined) pads are recommended. Take a look at this application note from Freescale for LGA notes relative to their parts.
We can assemble LGA parts for you. Count them as a BGA when you quote. For now, we'd like you to note the LGA part in the special instructions when placing your order. We'll probably give you a call to discuss the application before running them through.