Thanks! I appreciate your response :-)
I found this great article in addition ---
http://www.ti.com/lit/an/sprabb3/sprabb3.pdf
On Wed, Jun 14, 2017 at 5:31 PM, Simon FAU <simon.fau89@xxxxxxxxx> wrote:
Hi,
Some hints to help you with BGA.
Regarding PCB Fab:
- Specify maximum bow and twist to limit mechanical constraints on BGA
components
- Choose a surface finish adapted to BGA (avoid HASL which provide
uneven surface)
- If using via-in-pad, be sure your PCB fab master this technology
Regarding EMS:
- Ask for post-soldering X-Ray of BGA components, on all boards or at
least some. Not all EMS (especially small prototyping ones) are equipped
with X-Ray, so asked them, because for few quantities they can use one
from
another company. At least non-functionning board should have X-Ray on
suscepted NOK BGA components.
- Ask your EMS about BGA pitch it could produce, and ask what you should
do to your design to improve yield.
- Fine pitch BGA means small pads and it needs precise solder paste
stencils, so ask your EMS about solder paste stencil and what it could
do.
The more complex your board is, the more you should discuss with your PCB
fab and EMS, especially when prototyping small quantities.
I asked a prototyping EMS for his feedback on a board he manufactures for
us (around 100 pieces) with two BGA, one in 0.8mm pitch and the other one
0.5mm, and 0201 components. 0.5mm and 0201 were fairly new for him. We had
some defect at the beginning but he fixed his paste stencils and last
batches were totally ok. So now we know that for next projects with these
components we will have acceptable yield from the beginning, we're on the
long run.
BGA reliability is more about mechanical and temperature constraints rather
than bad pad design (if you follow component recommandations).
Regards,
Simon
2017-06-14 23:41 GMT+02:00 SI Guy <silistguy@xxxxxxxxx>:
Hello guys, been having some great convos here lately, and you all haveon
been most helpful.
Question now,
I have been traversing through Coomb's Handbook and ran across a chapter
BGA reliability. I'm finding it interesting, talking about SMD and NSMDand
effective CTE, etc.. I did some more research online and WOW, theissue
conflicting views of SMD and NSMD there are...
I'm going to get to the punchline. I saw pictures of solder ball joints
breaking at not only the pcb pad but also at the pkg to ball joint! Scary
stuff I hope to never endure. After reading, it looks like the CTE xy
mismatch of silicon and standard pcb materials is what is the biggest
here, among other things. This is where I like to ask the experts herefor
advice because this seems like a job almost in and of itself ;-)discuss
As a layout guy, I'm pondering, what are good do's AND don'ts to help BGA
reliability (not sure the proper term) from a layout perspective and also
what are somethings I might would want to put in a fab document or
with a fab house to help aid in this 'venture as well? Let's assume we'reof
doing VIP or dog-bone fanout or outerlayer trace to pad or combinations
sorts. I don't expect us to cover all corners, but details are nice!
Thanks, guys.
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