When does maintenance become too much?

Repairing high reliability circuit boards is not an easy task, but it’s often far more cost effective than replacing these costly units. Soldering replacement chips to the board will keep a complex, expensive board running. But for how long?

When technicians put their soldering irons to the board and skillfully replace these chips, the heat puts stress on the board and nearby components. That raises the question of how many times these parts can be stressed before these repairs start creating more failures. The cost benefits of repairs can quickly be overcome by the high expense of an unexpected failure.

“In terms of rework, cost is a consideration. However, long term reliability has to be the top priority for mission critical products,” said Hongtao Ma, Ph.D., electronic packaging reliability engineer at Cisco Systems Inc.

Ma has extensively investigated the effects of multiple rework on the reliability of lead-free solders, which require higher soldering temperatures than the lead-based solders once used on high rel boards. His research showed that multiple reworks significantly degraded the ATC performance of the reworked assemblies by up to 50% in terms of characteristic life.

Several more important findings also arose during this study. Ma will detail them at the IPC Conference on Reliability: Assembly Process for a Reliable Product, a two-day conference that opens Nov. 1 in Irvine, Calif.

One Comment

  1. Posted March 9, 2012 at 7:40 am | Permalink

    Repairing twice or thrice is fine i believe. Beyond that i’d choose for replacement. Good post.


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