Flex circuits versus wired - What’s better?

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Travis Neumann answers a topical question in the field of connectors

Products often start their life as a put together solution to accomplish the goal in the shortest path possible. Although this path does help to create and build the concept, it may not be the most efficient for manufacturing. A product that started with one assembly solution and transitioned to a different method in a smaller form factor is what we’re investigating here.

This connector solution is used on crash test dummies to transfer impact data for analysis. Initially the connector solution was a larger size and used wires to bridge between the micro and nano contacts. Customer asked for a smaller form factor and the transition to flex was brought in as a solution.

Omnetics had the task of delivering a small connector that bridged 36 Micro-D connections to 36 Nano-D at a right angle. Creating that bridge proved to be time consuming in terms of production.  Not only is there 36in of wire packed into a space smaller than a sugar cube, the wiring is not straightforward pin 1 to pin 1, pin 2 to pin 2 etc., so it’s very time consuming.

What are the benefits of flex circuits?

Moving to flex provides a number of advantages. Flex arrives 100% tested, so only known good flex circuits are used ensuring there are no wiring errors. Additionally, it allows use of standard processes found in electronics such as pin and paste and vapour phase soldering. Form factor reduction is also a benefit of moving to flex, as there is minimal spacing between traces and everything is moved in a neat and orderly fashion. Housings are now smaller as well requiring less machining, both from the overall size and the fact the flex circuit requires less volume inside the housing.

This wiring took a fair amount of time to create in manufacturing for reference, to wire the micro to nano contacts for a job of 150 connectors took three days. Moving to flex greatly improved that time. Omnetics was able to use a standard nano housing, with leads for surface mount and through hole. The micro side uses through holes and both the connectors are soldered to the flex at the same time. This allows manufacturing to perform this same “wiring” step in half a day for those same 150 connectors.

Improved time and quality with flex circuits

Innovation is not typically a factor when one or two parts are needed for a solution with volume production tends to present many opportunities for improvement. In this case manufacturing time was able to be improved while maintaining quality.

Travis Neumann is special project manager at Omnetics

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