William,
For item #7, concerning if the adhesive will lift the part during reflow
oven cure. It is not clear whether you are doing a cure process only, or
attempting to cure while reflowing solder on other components. The elevated
cure is an issue- because like you said it will lift components. The
adhesive actually cures while still outgassing, and thus little voids are
formed in the joint. Structurally not a huge problem, but if you are using
enough adhesive, you will get the lifting effect.
The Heraues PD8600002 and the Loctite formulas (3609 and 3610 at least) have
this expansion problem when curing at reflow tempreatures (215C max). I did
read that Heraeus has a SMT adhesive formula for use with elevated cure
temperatures (ie- an adhesuve and solder paste combo process).
Hope this helps. If you are not running a combo process, then curing at
normal temps we have had success with the Heraeus PD8600002 and Loctite 3609
for dispense, curing, and reworking.
Steve Abrahamson
> -----Original Message-----
> From: Mengers, William D. [SMTP:[log in to unmask]]
> Sent: Tuesday,June 19,2001 7:03 AM
> To: [log in to unmask]
> Subject: [TN] SMT adhesive
>
> Hi All,
>
> I am looking for an SMT adhesive with the following characteristics:
>
> 1. 1 part
> 2. Dispensible
> 3. Thermal (not sure of a number here)
> 4. Snap cure (re-flow)
> 5. Re-workable
> 6. Extended work life (prefer several days)
> 7. Will not lift parts during cure in re-flow oven)
>
> Please tell me I'm not asking for much. We are presently using LocTite
> 3615
> which dispenses great, but happens not to be a "thermal" adhesive and is
> not
> reworkable. And, unfortunately, we have not matured enough to learn from
> our mistakes and get rid of re-work. Or even keep it to a minimum, but
> that
> is a story in itself.
>
> I would like to "stick" with a large company with plenty of resources,
> e.g.
> LocTite. Any reccommendations?
>
> Thanks for any info you can give,
>
> Bill Mengers
> Process Engineer
> Northrop Grumman Corp.
> Baltimore, Md.
>
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