Issue link: https://iconnect007.uberflip.com/i/1529411
18 PCB007 MAGAZINE I NOVEMBER 2024 agate to the surroundings. He was also using microvias, and if you're using microvias, you're limiting yourself to laser drilling technol- ogy which means there's a maximum distance between layers one and two. Normally, if you want a high impedance, the easy thing to do is to increase the distance to all the other layers. With laser drilling, you can't do this. e only thing you can do is change the material. In that case, there were only about two or three spe- cial materials on the market that would work, for instance, a PTFE material. ey are costly and have to be specially ordered. e imped- ance is driving this need. At that point, you talk with the customer about cost drivers and hard build requirements. If not for the impedance call-out, we could use standard materials. We want to make sure it's necessary. Exotic mate- rials also increase your procurement time and, oen, your lead time. That leads to delaying time-to-market increases in costs as well. The use of more exotic materials must be largely dependent on the end applications: medical, auto- motive, defense, high-speed, and extreme heat or cold. Yes. ere's also the need for special product certifications, another cost adder common in medical and automotive, for example. If a specific product certification is required, one that applies only to that product in a very spe- cific construction or finished state, you cannot change anything. If you change the materials, even if the finished product has all the same properties, nobody's willing to take that risk. You can recertify based on the new build-up but who will pay for that? It takes time to get certification and approval. Richard, can you share an experience or situation that you've learned from particularly? Regarding standards and certifications, we have a fire protection standard in Europe for trains. In one situation, we sent a PCB design to the PCB manufacturer and then the product to the customer, the assembler. e product then was shipped to their customer, who built a casing around it and sold it as their prod- uct to a train manufacturer. One of the train manufacturer's quality guys asked for the fire safety certification and for their vendor to pro- vide it. is request went to the guy who made the encasement, who shipped the final prod- uct to the train company but did not build the whole product. Setting aside whether the cas- ing manufacturer knew it was going into a train product, he was shipping to the end customer and a certification was required. He went back to the EMS provider and asked them for cer- tification. e provider then began contact- ing every supplier on his 500-part-long BOM. Finally, the request for the flame-retardant cer- tification went to the PCB fabricator two years aer delivery. How did that even happen? It's shocking that it wasn't clear up front, but I'm sure it happens. e funny part is I'm pretty sure most of the materials used would have passed a correspond- ing flammability test for certification if it had been undertaken. But the corresponding test at a certified lab costs a lot of money. We could have Richard Koensgen