Thanks Werner. Yes, your column was very helpful. Sounds like my
question may be a bit naive and that I am trying to simplify things too
much. I was searching for an IPC guideline or to at least start a
discussion on the subject, but maybe this is a proprietary area. Fellow
TechNetters: is that the case?
Have a great day,
Ed
Werner Engelmaier /* wrote:
> Hi Ed,
> Underfill makes solder attachments sufficiently reliable in cases where without it solder joint failures would occur prematurely for the application in question. As work by Motorola [see my reliability column Engelmaier, W., “Reliability Improvement with Underfill,” Global SMT & Packaging, Vol. 6, No. 3, March 2006, pp. 66-67] has shown, not all underfills are of equal benefit and that increases of up to 6x are achievable in praxis.
> If the reliability without the underfill is sufficient—because of small component size, high solder joint stand-off, built-in component compliancy [Tessera patents], small CTE-mismatch, small delta-T, then there is no need for underfills.
> Werner
>
>
>
>
>
>
>
> -----Original Message-----
> From: Edward Rios <[log in to unmask]>
> To: [log in to unmask]
> Sent: Wed, 3 Jun 2009 5:45 pm
> Subject: [TN] When not to underfill
>
>
>
>
>
>
>
>
>
> Hi TechNet,
>
>
> OK I'll admit it, I'm fairly new to the field of solder joint
> reliability. ;) Therefore, the recent thread about underfill inspection
> criteria prompted me to do additional reading on the subject. It seems
> like there is consensus on the positive effect of underfilling on BGA
> solder joint reliability. On the other hand, are there cases where
> underfill doesn't have a significant impact? Maybe in smaller BGA
> components?
>
>
> Thanks,
>
>
> Ed Rios
>
>
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