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Method of Uniform Bend Testing of Circuit Assemblies

IP.com Disclosure Number: IPCOM000059799D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Foster, RA: AUTHOR

Abstract

A method which insures consistent bending of circuit assemblies and, therefore, uniform results is described. Quality and reliability assessments of electronic package assemblies, especially those utilizing surface-mounted components, involve bending the panel assembly. Conventionally, this is done utilizing a fixture, as illustrated in Figs. 1A - 1C. As shown, the circuit panel 1 under test is supported by pairs of cylinders along two opposite edges 2. This allows the panel 1 to curve in a cylindrical arc when displaced by the center cylinder pair 3. In order that the stress be uniform across each panel and on all different panels tested, the displacement of movable member 3 should cause smooth, consistent bending.

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Method of Uniform Bend Testing of Circuit Assemblies

A method which insures consistent bending of circuit assemblies and, therefore, uniform results is described. Quality and reliability assessments of electronic package assemblies, especially those utilizing surface-mounted components, involve bending the panel assembly. Conventionally, this is done utilizing a fixture, as illustrated in Figs. 1A - 1C. As shown, the circuit panel 1 under test is supported by pairs of cylinders along two opposite edges 2. This allows the panel 1 to curve in a cylindrical arc when displaced by the center cylinder pair 3. In order that the stress be uniform across each panel and on all different panels tested, the displacement of movable member 3 should cause smooth, consistent bending. This is not realized in practice since various component populations will distort the bending into non-uniform geometries, causing stress concentrations on some components and low stress on others. To insure uniform bending, the panel 20 is wrapped around an arc of a large cylinder 21, as shown in Figs. 2A and 2B. Circuit panel 20 is mounted in the fixture by placing one edge 22 in grooved block 23. Pressure is applied to the surface of the panel 24 manually or with appropriate apparatus wrapping the panel around mandrel 21, forcing it to conform to its curvature. Bending in both directions may be achieved by turning the panel over or using a double-mandrel fixture, as shown in Fig. 3. The mandrel f...