I concur with Roger, hydrogen in plating is a likely answer. Sometimes it can be
baked out, but usually the answer is to strip/replate or replace.
Verify by baking out, or using product from a previous batch without the problem. Or
mimic your process on any piece of unplated metal. [Changing nothing else.]
Mike Fenner
BSP, OX15 4JQ, England
T: +44 1295 722 992
M: +44 789 999 7715
F: +44 1295 720 937
-----Original Message-----
From: Roger Massey-G14195 <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: 12 August 1999 14:14
Subject: [TN] Re Ingemars question
> Ingemar,
>
> Strange question but ,does the adhesive film completely, or very
> nearly cover the heat spreader, if not, are there microbubbles, or
> surface voids occuring on the spreader itself but in areas not covered
> with the adhesive?
> If the adhesive film covers the spreader area, can you process some
> blank heatspreaders, and take a look at them.
>
> The reason I suggest this, and I dont know if you have already
> followed this avenue, is that the platings you have described can
> absorb Hydrogen during the plating operation, this will remain within
> the plated layer until it gets nice and hot and then will bubble up
> and make a nice mess of a flat surface.
>
> A simple screening test by heat (300C for 1hr, or just use your
> process oven) will allow the entrapped gas to escape, the bad thing is
> that if the parts are suffering from this, there is nothing you can do
> except send them back to the supplier, and ask that they strip and
> replate them. This is cheap test, and only needs a furnace and a
> microscope.
>
> Another potentially quicker way of doing this is to measure
> microhardness of a good and bad part. the entrapped gas will harden
> the Au and Ni plating if present. Downer is that you need a
> microhardness tester
>
> Good Luck
>
> Roger
> Motorola AIEG
>
>
>______________________________ Reply Separator _________________________________
>Subject: Re: [TN] Where are the others?
>Author: "TechNet E-Mail Forum." <[log in to unmask]> at #email
>Date: 12/08/99 14:14
>
>
>Sure, Graham,
>maybe some misunderstanding (joking must be correctly formulated), I
>don't mean to use french language, just tried to make a baite so someone
>from a french company came in. I'm still wondering why the french
>companies are so reserved in this forum.
>Now, Graham, forget my question, I leave the issue completely, instead I
>have something for you and possibly someone else: how do you 1)verify
>2)get rid of built-in gas or gas-creating micromaterial in a metal plate
>or a Au/Ni/Cu-Mo plate? We mount large semiconductor chips on
>heat-spreader by means of a thermoplastic film. The supplier of this film
>is one of the most familiar, they have specified Tg, outgassing, and all
>other chemical factors, and it seems as this film transer will not cause
>gas to grow under the chip during curing. But we get bubbles between the
>film and the heat spreader. The american thermoplastic film supplier has
>inspected our line and concept and he can't understand the bubble's
>origin. Can't be the transfer, he said.
>If extremly advanced or unusual equipments are needed for such
>evaluation, can you help us Graham? I can send a photo to you so you get
>more than words. Maybe IMAPS is a more correct adress for such
>questions, but I suspect many of you are in there too.
>
>Best wishes
>
>/Ingemar Hernefjord
>Ericsson Microwave Systems
>
>
>
>---------------------------separator---------------------------------
>> Ingemar,
>>
>> You know one of the major drawbacks of the whole "Internet" thing, is
>that
>> you MUST speak / read / write English.
>>
>> Curious thing is, most of the planet don't!
>>
>> In my experience, France, Italy, Spain are hors de combat! (Good old
>English
>> expression!)
>>
>> Of course there are those cynics who would point out that the UK and
>the USA
>> are 2 nations divided by a common language.
>>
>> And if you think this is bad, take a look at my reply to Vincent
>BADA....
>>
>> Regards,
>> Graham Naisbitt
>>
>> [log in to unmask]
>>
>> WEB: http://www.concoat.co.uk
>>
>> CONCOAT Ltd
>> Alasan House, Albany Park
>> CAMBERLEY GU15 2PL UK
>>
>> Tel: +44 (0) 1276 691100 Fax: +44 (0) 1276 691227
>
>>
>
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