Issue link: https://iconnect007.uberflip.com/i/921680
18 SMT007 MAGAZINE I JANUARY 2018 more complex prod- ucts like rigid-flex and HDI construc- tions. In these types of products, the material set is going to play a key role in how the boards are going to process and yield for tight toler - ance items such as Class 3 annular ring or wrap plat- ing requirements. For more complex designs you need to understand and select materials correctly, and design appropriately. Design - ers don't necessarily understand the myriad of manufacturing challenges the PCB producer must navigate when they are evaluating mate - rials 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 process, and, in general, what they can and can't do. Because the problem nowadays with PCB design is that the barriers to entry for somebody to call themselves a PCB designer are so low. There are so many people out there as contractors. More and more, even large companies are moving toward a contractor model. There are some bad designers out there that don't know anything about PCB fabrica- tion, they don't know anything about what the EMS company has to do, and they come out with some really, really bad layouts that are almost unproducible," he notes. "And the problem is, with a lot of the ways the contract- ing worlds work, by the time it comes to Kathy and myself, the design 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 off, 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 going to ask the right ques- tions, and just produce something that isn't manufacturable." One of the issues that challenges manu- facturers like Eltek is how we as an industry approach 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 utiliza - tion on a standard panel is wasteful. Net result is the cost is going higher than predicted, or the board needs design modification and ultimately the customers' end target for time to market, price or both is missed. It's an important factor that can get missed when dealing 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 fabrication side is that when you're building prototype quantities, the manufacturability sometimes gets lost in the equation. "Because when you're buying one board or three boards, it's either going to cost you a lot or it's going to cost you a whole lot. If it's going to have a high repeatable 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 production 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