In a previous incarnation, we attached a flex circuit to thick film. 
     We also did HTCC.
     
     The flex was HASL. We used hot bar to attach.
     
     If you have any other questions, please email me direct.
     
     Paul Stolar
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: [TN] Hot bar soldering flex on ceramic
Author:  [log in to unmask]>                Matthias Mansfeld 
<[log in to unmask] at internet
Date:    10/7/98 7:10 PM


Hello TechNetters/ Designers,

I'm working on my first design with flex on ceramic. A semi-rigid
board with a lot of SMD stuff (two copper layers) has to be TAB-like
hot bar soldered with its one-layer-flex-end to an Aluminiumoxide
ceramic substrate with AgPd traces (good old thick film technology)
and two wirebonded chips (one of them a pressure sensor) on it.
I need a not too expensive but reliable technology, because it will
be a mass product for automotive application under the hood (about
150° C max.). The whole assembly will be "folded" in a sealed
housing.

My question is, where can I find good design rules for both sides of
the solder connection? Solder depot on one or both sides? Solder
paste printing/dispensing? Which surface finish on the flex side?
HASL, chemical tin, NiAu?
Any experiences about the reliability of these constructions?

Thanks in advance, regards
Matthias Mansfeld
-----------------------------------------------
Matthias Mansfeld Elektronik
* Printed Circuit Board Design and Assembly
Am Langhoelzl 11, D-85540 Haar, GERMANY
Phone: +49-89-4620 0937, Fax: +49-89-4620 0938
E-Mail: [log in to unmask]
Internet: http://www.mansfeld-elektronik.de

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