Issue link: https://iconnect007.uberflip.com/i/1441485
102 DESIGN007 MAGAZINE I JANUARY 2022 ments. TTCI works with fix- ture partners to offer custom in-house solutions to support and access these challenging assemblies. Shaughnessy: What are the most common tests for flex- ible circuit assemblies as well as the biggest challenges? Do high-voltage flexible circuits require a different set of tests than the rest? Horner: For flying probe testing (FPT), in-circuit testing (ICT) and functional test (FT), the biggest challenge is the tooling for testing the assembly. For the FPT, the handling of the unit under test (UUT) is one of the biggest challenges. is can still be a challenge if the assembly is thin and flimsy, so tooling could still be required. If ICT and FT are done on a fixture or bed-of-nails (BoN), we don't want to introduce stress to the UUT, so "zero flex" fixturing with finite element analy- sis (FEA) and strain gauge might be needed, which also adds time and cost. In FT, we see that in high-voltage testing, the biggest chal- lenge is making sure the equipment that will be testing assembly can handle the proper test- ing requirements. is is about the same set-up as a rigid board, but we haven't seen too many applications that have this as a requirement. Shaughnessy: What are some of the biggest dif- ferences between testing a flexible circuit and a traditional rigid PCB? Horner: e physical handling is the biggest challenge in testing flex or rigid-flex circuitry. We oen have to develop a custom carrier or handling fixture to test flex or rigid-flex assem- blies to help with stability and support. Shaughnessy: We've seen flex and rigid-flex explode in the last decade, and now flex can be found in many household and handheld devices. What trends are you seeing in the world of flex? Horner: Test access is more of a challenge with accessing the test assemblies through connectors and SMT device "toes" of the solder joints with the assemblies going into two completely differ- ent directions. e wearable, handheld, and space applica- tions are getting smaller, but the defense backplanes are in some cases getting larger. Shaughnessy: How much of your job involves educating new customers about flex and test- ing? Horner: We are educating the customer by showing them strengths and weaknesses in the test solutions they are choosing or that they have available to test their assemblies. If we are looking at multiple test and inspection tools to get the most coverage on these assemblies, the education becomes about what is best for manufacturing. We both learn preferences of tools that are available. Shaughnessy: Is there anything else you'd like to add? Horner: ere are more similarities of testing flex circuitry and conventional rigid circuitry; the access, and the handling are where we see the challenge. Shaughnessy: anks for your time, Bert. Horner: ank you for the opportunity, Andy. FLEX007 Bert Horner