Larry:

Why are you worried about PEMs on your circuit?

Do you not have capacitors, filters, Ceramic chip capacitors?

As the reflow temp. is raised, die-attach solders will likely melt, plastics 
will degrade and items like solder masks may  also cause heartaches.

If this is a long life (or high-rel assembly) could you approach this with  a 
more global perspective than simply PEMs.

More feedback is welcome.

G.S.S. Prasad

______________________________ Reply Separator _________________________________
Subject: FW: PEM reflow
Author:  [log in to unmask]@INTERNET at #EMAIL
Date:    6/6/97 01:16 PM


TechNetters,
     I am trying to help a customer with this problem, but I have limited experi
ence
with reflow temperatures this high, so I am forwarding this to all of you in 
hopes that someone will be able to help him.  The only thing I will add to it is
     
for a military application.
     
Thanks in advance.
     
John Guy
American Competitiveness Institute (EMPF) 
714 N. Senate Ave.
Indianapolis, IN 46202-3112
Tel:     (317) 655-EMPF x130
fax:     (317) 655-3699
e-mail:      [log in to unmask]
     
Hello Guy,
     
The question is if there is a relationship between reflow temperature, time 
at temperature and functional reliability.  There are two soldering systems 
being investigated neither of them using an IR reflow system.  Parameters 
involved are reflow temperature of 250 to 260 C, time at temperature of 5 or 
40 seconds for single reflow and 10 or 80 seconds for double reflow. 
Questions, will the increased reflow times effect the reliability of the 
PEM's,  what would be effected and to what degree would the effect have?
     
Larry
     
PS  Thank you in advance.
     
     
     
     
     
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