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June 2004

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Subject:
From:
Richard Kraszewski <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 22 Jun 2004 14:23:20 -0500
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text/plain (71 lines)
This doesn't answer you questions directly but still may be of some use
in your decision. 

IPC SM-785, sections 3.4.3 & 7.3.3 goes into these issues. They briefly
present the differences in stresses applied by each (TS vs. TC) and
summarize stating that TS for SM is only recommended if the TS
conditions are likely to be encountered in actual field use by the
product. 

IPC 9701 goes into the details of selecting the test parameters and may
be of some use to you.

Rich Kraszewski 
Advanced Manufacturing Engineer - KEDS
Phone:  260.925.8919
 
 
 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Marsico, James
Sent: Tuesday, June 22, 2004 1:27 PM
To: [log in to unmask]
Subject: [TN] Shock vs. Cycling


Good day Technet:
I will be starting an evaluation shortly to determine the reliability of
soldering RF components (no compliant leads, flat leads coming right out
of the bottom of the package) directly to the PWB.  (In the past we
always soldered ribbon jumper leads from the component leads down to the
PWB to ensure strain relief.)  We intend to subject the test hardware to
thermal excursions typical of the actual hardware environment.  My
question is which, if any, is the worst case with regard to longevity of
the solder joints, thermal shock, with virtually no ramp between
temperature extremes, or thermal cycling, with a ramp of, lets say, a
minimum of 5 degrees C per minute?  Opinions are OK, but if you have
technical justification for your answer, it will be appreciated.

Thanks in advance,

Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]> 631-595-5879

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