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November 2004

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Subject:
From:
"Creswick, Steven" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Creswick, Steven
Date:
Tue, 9 Nov 2004 08:44:00 -0500
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Ramon,

In the hybrid microelectronics industry one generally heats up the defective [bare] chip with directed hot gas [substrate and surrounding components limit the max temp, but 150-200°C is not uncommon], then mechanically shear the defective device off.  

Using a dental chisel [manually], or equivalent, one cleans up the substrate - removing the bulk of the previous adhesive.  Depending on the product, there may be additional cleaning, but bottom line being that ultimately fresh adhesive and device are then re-placed and cured.

I have only played just a wee bit with adhesively bonded SMT components.  I bet that in many cases you could take your fingernail and pop some of them off!  Although, heating to just above the glass transition temp of the adhesive always makes it easier.

As someone already posted [to paraphrase], "If it was so great, every one would be doing it!"

Something low cost, disposable, very benign environment - those might be applications.

Steve

-----Original Message-----
From: Dehoyos, Ramon [mailto:[log in to unmask]]
Sent: Tuesday, November 09, 2004 8:24 AM
To: [log in to unmask]
Subject: Re: [TN] Conductive Adhesive


        Anybody:
        How do you remove the conductive adhesives to replace a component? Do they work for SMT as well as for THT?
        Regards,
        Ramon

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