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June 2014 • The PCB Design Magazine 19 materials including highly unnatural films and adhesives that are produced by film makers and compounders from polymers, which are in turn produced by other chemical companies. This is a much more complex supply chain with multiple layers of manufacturers. Latent defects are the rule. And that's just for the raw materials; making nuts and bolts is primarily an automated machine-shop enterprise, while FPC production takes multiple interacting pro- cesses using thermal, chemical and mechanical forces and process equipment all influenced by both operator skill and latent defects in those complex raw materials. There is no comparison in degree-of-difficulty and the horrors of com- pounding yield losses, but this only adds to the argument: If the situation were reversed and the complex product was a commodity and the easy-to-build product was custom made, these problems would disappear. But FPC is the tough one to make and can't be sold from a catalog be- cause it's a custom product. You sell something that you have; you contract to make something you don't have. Selling something you don't have is pretty close to fraud. Competition, Second Sources and Partner Selection What about competition? PB&S makes a catalog product, but so do all of the other bolt and screw makers of the world. If your project needs 1,000, 1/4-20 round head 1" brass screws per day and Paradise can't supply them, there's always somebody else with an identical and fully interchangeable part that can. In the case of an FPC buy, a hiccup at the factory—your personally selected, custom-con- tracted factory—means that you start produc- tion all over again: there's no backup supplier ready to ship on demand. You selected a pro- WHY PRoCURINg FLExIBLE PRINTED CIRCUITRY IS DIFFERENT continues feature Figure 4: Four connectors: a three-layer FPC with central shield. Terminations are plated through and have soldered connectors.