Mike (and Technet),
1. We published our first paper on the use of Thermabond in spacecraft in
1990 and have been using it ever since.
2. I have no idea what the life expectancy is since we haven't done any
very long term tests. We did lots of thermal cycling to verify that it'd
survive the satellite lifetimes of several years, though.
3. We've cycled the stuff from -55C to 125C but have done no humidity
exposure tests since our end use environment doesn't have that issue.
We've also exposed assemblies with bonded on heatsinks to solder reflow
temperatures and found that, by proper design, the adhesion was only
slightly affected.
As an aside, our typical heat sink is aluminum with the side bonded
by the Thermabond untreated. We have also successfully used nickel plated
copper heat sinks (one was very large, about 8" x 11" x 0.060thk).
Hope that helps.
Howard
At 11:30 AM 10/17/97 -0400, ADAMS, Mike wrote:
>Howard,
> Would you provide me with more information like:
>1. How long you have been using Thermabond?
>2. What is the life expectancy of the application (i.e., will the
>Thermabond still be adhering the heatsink to the pwb near end-of-life?)?
>3. What environmental conditions (temp & humidity extremes) will the
>Thermabond be exposed to?
>
> Any info in this area would be quite helpful.
>
>Thanks,
>
>Mike Adams
>Lucas Aerospace
>[log in to unmask]
>(216)995-1195 x3058
>
>> ----------
>> From: Howard Feldmesser[SMTP:[log in to unmask]]
>> Sent: Thursday, October 16, 1997 4:24 PM
>> To: [log in to unmask]
>> Subject: Re: [TECHNET] Heatsink lamination
>>
>> Marty,
>> We've had very bad luck with bonding heatsinks with prepreg,
>> most
>> often resulting in a board that looks like a potato chip. Several
>> years
>> ago we switched to Arlon's Thermabond with great success. We've
>> launched
>> several satellites with bonded on heatsinks and all are still
>> functional, a
>> true test of surviving rigorous use.
>> Howard Feldmesser
>> The Johns Hopkins University Applied Physics Laboratory
>>
>> At 2:54 PM 10/16/97 -0400, Sheppard, Marty - LYPME wrote:
>> >We are attempting to attach a nickel-plated copper heatsink to a 10
>> >layer PWB per a set of manufacturing drawings that only states that
>> "the
>> >heatsink shall be attached with prepreg". It does not call out a
>> >pressure, temperature, cycle time, or a type of prepreg. We have
>> >assumed that we would need a "low-flow" type of prepreg. We have
>> tried
>> >some sample cards with a low-flow prepreg (PC-GF 108V by Westinghouse
>> >Fortin) that we have on hand; we have had good registration of the
>> >heatsink to card, but the adhesion has not been as good as we would
>> have
>> >liked, and the heatsink seems to have been pressed "into" the board
>> (you
>> >can feel the outline of the heatsink on the backside of the card).
>> We
>> >ran the press at the lowest possible pressure we can for our press
>> (15
>> >lbs).
>> >
>> >We are looking for suggestions from anyone who has experience with
>> >laminating heatsinks to PWBs.
>> >
>> >Thanks,
>> >
>> >Marty W. Sheppard / LYPME
>> >Manufacturing Engineering Support
>> >(912)-926-9632 DSN 468-9632 Fax: (912)926-7974
>> >email: [log in to unmask]
>> >
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