Issue link: https://iconnect007.uberflip.com/i/1116895
MAY 2019 I PCB007 MAGAZINE 41 a finer point than before. But below a certain point (maybe 20–25 microns), the subtrac- tive product starts to have is- sues. It has been reported that companies like Apple and their iPhones are using the modified semi-additive pro- cess. There's more of a switch from a subtractive world to an additive or semi-additive world to get that next level of resolution. And the pho- toresists are capable of doing that; it's just a matter of the overall process. As we start getting into those fine lines and spaces, everything becomes an issue. The materials, processes, environment, and pretty much everything must be under tight control. It has been reported that the initial yields have not been very good, but they are getting better. Matties: I'm seeing a lot of roll-to-roll applica- tions being represented at the FLEXCon Show. What materials do people need to be aware of in that arena? Andresakis: Considering that our business is flex materials, that's something that we hope catches on with people because our materi- al can be supplied in roll form. It lends itself very well to this process since polyimide is a robust substrate. For certain electronics that don't have to deal with any temperature ex- tremes or harsh environments, you might use the cheapest film available, such as PET. But if you want a high-performing material, then our polyimides lend themselves very well. The other area where our polyimides are coming into play is that we make a clear polyimide, which can be used for flexible displays. Feinberg: Flex materials could be seeing a huge increase in interest and use, especially with the new foldable, portable devices. Suddenly, we're going to have a 7-inch computer that you can fold in half and use as a phone or for a terminal. It's interesting that you mentioned it because I think foldable and stretchable things are going to be a big factor and pose some huge demands from designers. Andresakis: Royole was the first one to an- nounce a folding phone, and now Samsung has released one. They were at CES, so flex- ible displays and foldable phones are definite- ly here. LG had a roll-up TV that might have been on the Willow Glass from Corning with a plastic overlay, but the big substrate was glass. There's also going to be a boost in cellphone sales once 5G hits, but the foldable ones are the next thing to get people to upgrade their technology. However, I think most people are going to wait and see about their reliability. Even though they can guarantee so many folds, early adopters are going to check out that tech- nology and see how robust it really is. Matties: What's amazing is the number of ma- terials that are on the market. What advice would you give to designers and OEMs so that they can keep up with all the latest materials? Andresakis: Often, they rely on their supply chain. But every OEM should spend time going directly to the material suppliers and working closely with them, especially on new develop- ments, because then they will see what people are working on and can learn about the latest and greatest materials. Also, attending confer- As seen at CES 2019, the Royole FlexPai foldable smartphone and tablet in one.