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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: Rob (getreliability@designanalytx.com )
Date posted: Thu Jul 27 15:10:25 US/Eastern 2000
Subject: IR Soldering
Message:
I'm looking for information on IR (Infrared) Soldering, both process and reliability data (failure rates, or failure modes/mechanisms).


Reply:

Subject: IR Soldering
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Mon Jul 31 15:08:13 US/Eastern 2000
Message:
Looking at the solder world one can differentiate circuit board production soldering techniques to either wave or reflow. Wave solder is well suited for aplicatons involving through-hole components. Reflow has advantages for surface mount components. The failure modes/mechanisims for reflow IR and vapor phase soldering process include "tombstoning", solder starved or open joints, component shift, overstress due to thermal shock and solder balls. The general consensus is that wave soldering has disadvantges when processing dense surface mount components which include; need for adhesive attachment of the components, fluxing of the entire board, solder bridging and incomplete solder joint formation at the trailing edges of chip components. This wave solder technique requires strict board layout rules. For the reflow techniques, the IR solder process has an advantage if temperature sensitive components are used as the high temperature exposure time is less than one third that used in vapor phase soldering. Given an acceptable board layout and quality components, both IR and vapor phase have attained high reliable soldering results. Failure rates can be obtained from reliability handbooks based on the materials being connected and the temperature and vibration levels expected. The "Electronic Packaging and Production" magazine has numerous articles on soldering and component packages that should be reviewed.


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