Issue link: https://iconnect007.uberflip.com/i/924542
18 PCB007 MAGAZINE I JANUARY 2018 approach is not go- ing to fully address more complex prod- ucts like rigid-flex and HDI construc- tions. In these types of products, the ma- terial set is going to play a key role in how the boards are going to process and yield for tight tol- erance items such as Class 3 annular ring or wrap plating requirements. For more complex de - signs you need to un- derstand and select materials correctly, and de- sign appropriately. Designers don't necessarily under stand the myriad of manufacturing chal- lenges the PCB producer must navigate when the y are evaluating materials based primarily on electrical properties." Turpin agrees. "That would be my number one: Engage with a PCB fabricator. And, at a minimum, understand their pain and their pro - cess, and, in general, what they can and can't do. Because the problem nowadays with PCB design is that the barriers to entry for some - body to call themselves a PCB designer are so low. There are so many people out there as con- tractors. More and more, even large companies ar e moving toward a contractor model. There are some bad designers out there that don't know anything about PCB fabrication, they don't know anything about what the EMS com - pany has to do, and they come out with some r eally, really bad layouts that are almost unpro- ducible," he notes. "And the problem is, with a lot of the w ays the contracting worlds work, by the time it comes to Kathy and myself, the de - sign has been bought and paid for, and you've got a customer that really doesn't even know what it is they're dealing with. Then we've got to be the bad guy to tell them that, 'No, this really isn't going to work, and you've got to do this, this, and this.' And it slows things down. Or worse, they just don't have the time and they just try to build it as is. Or they go to some other bare board supplier that isn't go - ing to ask the right questions, and just produce something that isn't manufacturable." One of the issues that challenges manufac- turers like Eltek is how we as an industry ap- proach prototypes, according to Nargi-Toth. "If we look at the North American model today, we see a high number of prototypes that are being built in relatively small domestic facto- ries. The fact is that even if they are not in the best facility in the world, they can make one or two of anything and the design has been manufactured and is vetted as manufacturable. However, when you bring it to the production manufacturer they may say, 'We can't build this in production.' And by this they usually mean, the tolerances are too tight, the yield will be negatively impacted and the material utilization on a standard panel is wasteful. Net result is the cost is going higher than predict- ed, or the board needs design modification and ultimately the customers' end target for time to market, price or both is missed. It's an im- portant factor that can get missed when deal- ing with the prototype. It's best to work with a factory that can help you bring the product from design to market right from the start," she says. Turpin notes that the problem in the PCB fab- rication side is that when you're building pro- totype quantities, the manufacturability some- times gets lost in the equation. "Because when y ou're buying one board or three boards, it's ei- ther going to cost you a lot or it's going to cost y ou a whole lot. If it's going to have a high re- peatable cost, a lot of times it won't get caught until later ," says Turpin. "Right, and then when it goes into produc- tion, nobody wants to carry that poor design forward," says Nargi-Toth. "In the prototype model, you don't care what your yield is. You never track it because you're never going to see the part again. You make it one time and you're on to the next one. When it comes to produc - tion and you're going to be seeing the same part number every month, you can't live with a poor yielding design. That is what we try to avoid by early engagement with our customers." Matt Turpin, Zentech Manufacturing