12 Aug
2006
12 Aug
'06
10:09 a.m.
On Sat, 12 Aug 2006, Dave McGuire wrote:
Scott Quinn wrote:
Surface mount is good food...except BGA. What a huge pain in the butt. I
understand the need for that sort of density, but PCB routing for BGA is a
big pain, and as you stated, dealing with the chips physically really sucks.
I've done *all* types of surface mount stuff in my home lab...except for
BGA. The big show-stopper is the lack of means to inspect the soldering job.
Eventually I hope to obtain a small X-ray machine (of the type used for
bridge inspection, etc) to be able to check out the soldered balls.
(soldered balls...ow!)
-Dave
If you make sure that the balls are really melted (they flatten out) you can
usually get by by just sighting down under the BGA to make sure all the rows
between the balls are clear ( no merged balls). This means that you need to do
the BGA first so all sides are clear for visual inspection.
I've done lots of BGA protos with nothing more than a hot are gun and a lot of
flux (solder paste is not needed), they are really not so bad. (I've not done
any with smaller pitch than .8 mm as the initial alignment gets a bit picky)
Yup, get
ready to solder .2 mm balls on 800 balls BGA.
Get your toaster-oven ready ;-)
The really annoying thing about BGA is that I haven't figured a way to
desolder and reuse chips. Very vexing.
--
Dave McGuire
Cape Coral, FL
Peter Wallace