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A Test for Flux Entrapment

IP.com Disclosure Number: IPCOM000061942D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09

Publishing Venue

IBM

Related People

Authors:
Goho, J [+details]

Abstract

A non-destructive qualitative test is provided in flex circuit soldering for determining whether flux is trapped between the flex circuit dielectric and a stiffener to which it is attached. Flex circuits are frequently adhesively attached to stiffeners to provide mechanical rigidity for that portion of the circuit which does not need to be flexible. The flex circuit is first wave soldered and cleaned. If solder flux remains on the flex circuit after these operations, it is subsequently trapped in the adhesive operation. If that happens, over time the flux corrode the vias, and may even penetrate to the electronics on the opposite side of the flex circuit. This test detects whether flux has been trapped in this manner.