If you got tight between conductors AND risk of humidity, then be careful using silver filled glues, because of silver migration.
Other possible disaster can be epoxybleeding, which happens when the wet chemistry leaves the printed dot, and wets far outside the site.
Extremly small dots can show inhomogenous curing. Speaking about 100 microns or less. More of a dispensing problem though.
Soldering occurs at ++200C and fluxes move off oxides and like, adhesives don't apply that way. So, it happens that you get wetting problems. These can be treacherous in that they are not visible, but can be indicated by a higher series resistance. The nanothin interface between glue and component is of crucial interest, not the bulk joint.
Large power chips may sometimes be wetted falsely in a way that all seems good from outside, nice wetting geometry and all that, but in fact you get a true joint only along the chip's periphery. Kind of a frame wetting, while most of the chip's underside does not wet at all.
Repair doesn't make you happy, needless tell why...
That may be enough of pessimistic views, don't want disencourage you. 'Glueing' works just fine.
Ingemar Hernefjord
Ericsson Microwave Systems
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Peter L
Sent: Friday, November 05, 2004 8:20 PM
To: [log in to unmask]
Subject: [TN] Conductive Adhesive
Hello Technet,
Can someone share their experience on Pros/cons (in particularly process
implication) of applying conductive adhesive Vs solder paste? We have a
request by one customer to investigate conductive adhesive (stencil print
compatible) as a potential substitute for Pb-Sn solder and eventually lead-
free.
Rgds,
Peter
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