Another under fill used is Floropel. Super thin and a little
pricey.
Ramon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, March 27, 2006 1:40 PM
To: [log in to unmask]
Subject: Re: [TN] Conformal coating and BGA
To answer further, no conformal coating should ever be applied
underneath a BGA. Some can absorb moisture and swell up, cracking the
solder joints. Do not attempt to use conformal coat as an underfill.
Also, I would not coat the tops of BGAs either, as some (most notably
the metal-top types) have internal or external heatspreaders that will
be insulated due to the conformal coating, causing premature component
failures.
If the danger of shorting is present due to moisture condensation or
other moisture or chemical atmosphere hazards are present, use an
appropriate underfill epoxy formulated for that purpose.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Macko, Joe @ IEC
Sent: Monday, March 27, 2006 11:37 AM
To: [log in to unmask]
Subject: Re: [TN] Conformal coating and BGA
Gil,
Hello.
I have not heard of any restriction or problems applying c/c to the tops
of BGAs however, this does not coat the solder joints (SJs) located
under the BGA package, which is required by IPC-A-610. So, c/c BGAs does
not apply c/c to the actual SJs located under the package, which
violates IPC-A-610 acceptability requirements. We have used various
wickable underfills to seal SJs located under BGA packages.
joe
-----Original Message-----
From: Zilber Gil [mailto:[log in to unmask]]
Sent: Monday, March 27, 2006 8:17 AM
To: [log in to unmask]
Subject: [TN] Conformal coating and BGA
Hello All,
Are their any restrictions of applying conformal coating on BGA
components (Mil, Jedec, etc.)-i.e. on top of the BGA, avoiding
underneath it, etc.?
Thanks,
Dr. Gil Zilber
Technologist, Elta system Ltd.
Tel. +972-8-8577240
Mobile +972-54-4983222
http://www.iai.co.il/site/en/iai.asp?pi=17887
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