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August 1999

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Subject:
From:
Roger Massey-G14195 <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 12 Aug 1999 14:11:49 +0100
Content-Type:
text/plain
Parts/Attachments:
Re: (131 lines)
     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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