Issue link: https://iconnect007.uberflip.com/i/1073397
30 FLEX007 MAGAZINE I JANUARY 2019 (GME) factory where GME is our largest rigid HDI manufacturing site in Guangzhou, China. Matties: You're doing large-volume flex manufacturing, correct? Zha: Yes, depending on how you define large volume. Within the entire flex and flex assem- bly industry, we are not among the largest ven- dors who are very large size and only focused on flex and flex assembly. But when you talk about rigid-flex and flex assembly, we do man- ufacture a considerable number of devices— up to a million pieces for quantity. Matties: We've talked about collaboration and material. Is there any other advice that you would offer for lowering cost, increasing yields, and reducing cycle time? Zha: First, I would suggest that you consult your PCB manufacturers even before you create your stackups, and work with them on the tradeoffs of different designing features because that is going to save costs in the long run. Secondly, to save the cost on "install flex," it can be treated differently from dynamic flex. With a relatively large bending radius and a relatively lower amount of bending in install flex, there is a possibility to consider semi-flex technology, for which you can use FR-4 mate- rial instead of just polyimide material. With this technology, you would still be able to real- ize 3D installation but of course with some tradeoffs on bendability. We offer all three different types of technolo- gies (dynamic flex, install flex with PI mate- rial, semi-flex with FR-4 material), so compar- ing them from a cost or process manufactur- ability perspective, semi-flex will be lower cost and easier to build compared to the traditional rigid-flex process. Matties: So, really understanding your application can drive the cost down—or up, if you're not careful? Zha: Definitely. Even which layer you make your flex circuit or how large you open a cavity matters. For rigid-flex, there are a lot of engineering considerations in the building process. A very small difference can generate a lot of headaches where they have to mitigate the risk by using a more complex process flow, and it's going to add to the cost. Thus, early involvement is key to rigid-flex design. Matties: Is there anything that we haven't talked about regarding flex and rigid-flex that you feel we should discuss? Zha: Regarding the flex material itself, the dimensional stability is not as good as rigid material. Therefore, for designers should not expect rigid-flex and the flex circuits to have similar design features as rigid. That's one of the most common mistakes we see. People simply change a part of the PCB into flex and don't understand why they suddenly have design rule change issues because the dimen- sional stability of the polyimide material is worse than FR-4 materials. That's one thing I think we need to caution the designers about as well. The main message I'm trying to con- vey is rigid-flex design and manufacturing need early involvement and compromises or optimizations from both sides to realize good quality and low-cost products. Matties: Clay, we certainly appreciate your expertise and all of your years of service in this industry. Thank you so much for spending time with us. Zha: Thank you, Barry. Ng: Thank you. FLEX007 With this technology, you would still be able to realize 3D installation but of course with some tradeoffs on bendability.