Machine Design

Flexible circuit helps shed light on optical inspection line

The L2 Illuminator employed in an optical inspection system provides uniform, high-intensity light. The Illuminator is used with equipment that inspects IC carriers and lead frames.

Careful placement of LEDS on lamp side panels provides uniform, highintensity lighting from all internal surfaces. The diode leads feed through die-cut holes and are soldered into place.

The 5 mil-thick flexible circuit, R/flex 2005, easily conforms to curved panels.

A die-cut flexible circuit solved a tricky assembly issue for Intelligent Reasoning Systems Inc. (IRSI), Austin, when it moved its new illuminator from prototype to full-scale production. The L2 Illuminator's domeshaped ceiling and two flat panels help supply uniform, high-intensity light needed for optical inspection of IC package leads. Light comes from an LED array arranged about the lamp side panels and dome.

IRSI engineers Al Lewin and Robert Tait, connected prototype lamp diodes to a power source with a traditional mechanical harness. This worked fine for test quantities, but, says Lewin, the harness configuration was impractical for full-scale production. To make the connection, the assembler would bend diode leads onto the unanchored harness and apply heat. One slip, and the assembler would have to repeat the operation. It was a two-handed job that yielded poor results, Lewin adds.

The engineers then turned to Mound Flextek, Miamisburg, Ohio, a company that specializes in flexible circuits and assemblies. A 5-mil-thick circuit film called R/flex 2005 was selected. Now, the operators simply roll the flexible circuit over the panel surface, feed the diode leads through die-cut holes, then solder the leads to circuit traces.

Thinner films reportedly ripped during this procedure, but the R/flex 2005 from Rogers Corp., Chandler, Ariz., has good tear resistance as well as high-bond strength. The circuit material has a UL 94VTM-0 flame rating and a thermal index of 221°F. According to Rogers, the laminates meet emerging European standards for environmental safety because they contain no biphenyls or biphenyloxide compounds. Furthermore, R/flex 2005 contains no CF and none is used in its manufacture.

Rogers Corp., Circuit Materials Div., 100 N. Dobson Rd., Chandler, AZ 85224 (480)917-5270, www.roger-corp/cmu

TAGS: Technologies
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