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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: Barry Ma (bma@anritsu.com )
Organization:Anritsu Company
Date posted: Wed May 9 17:33:29 US/Eastern 2001
Subject: Can HASS replace Burn-in
Message:
Reasons to replace burn-in on PCB or higher assembly level with HASS are said as follows. Burn-in is not effective today because component failure rate have improved by orders of magnitude. Other screens, such as all-axis vibration and high-rate thermal cycling, are vastly more cost effective today than burn-in on PCB or higher assembly level. What do you think of their opinion?


Reply:

Subject: Burn-in Testing of PCBs
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Mon May 21 13:24:32 US/Eastern 2001
Message:
From historical data collected by the Institute of Environmental Sciences, it was found that temperature cycling is the most effective stress screen when compared to swept sine vibration, constant high temperature, humidity, etc, for circuit board assemblies. The data revealed that 80% of the latent defects, particularly weak parts and connections that are sensitive to temperature cycling can be precipitated. The next most effective screen is random vibration. This is the reason why most manufacturer of electronic hardware have ESS tests that use only temperature cycling and random vibration. HASS is an accelerated form of ESS that may or may not be an acceptable alternative. If the HASS test parameters are within the design limits and no destructive life limiting stresses are applied, then this testing could be considered. For most electronic items, a well defined ESS temperature cycle test combimed with vibration is satisfactory to precipitated the defects on the test item.


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