Issue link: https://iconnect007.uberflip.com/i/1350598
12 PCB007 MAGAZINE I MARCH 2021 Matties: When you're designing the actual cir- cuit board? You're taking that into consider- ation? Klein: Yes, by designing the circuit board and the housing concept. More important than the board itself is the housing. It could be in the fu- ture that we have to use some fans to cool the electronics from the outside. at will change the game. en we will need protection meth- ods, specific components or a protective coat- ing on the PCB. But up to now, we try to avoid this by designing a proper housing of the elec- tronics. Happy Holden: Which is going to be the bigger challenge in the future: Finding the right ma- terials that have the appropriate cost levels, or finding the right fabricators that can consis- tently produce quality products if they can get those materials? Klein: at is a very interesting question be- cause the automotive market is under a great deal of cost pressure. We have to be careful se- electronics: very low loss or ultra-low loss ma- terials with suitable Dk and Df values. ese materials are normally a bit more brittle and not that robust regarding micro-cracks like the traditional materials. Taking into account the known failure modes like CAF or micro- cracks, this could be challenging. In the automotive environment, tempera- ture cycling and temperature storage are im- portant parameters. But it is the humidity for which we have to be really careful. Vehicles have subsystems that are always on with low power consumption. ere could be electro- chemical migration in these systems. If you have to use these new materials due to the high-speed electronic requirements, then we have to be very careful. erefore—at the mo- ment—we have solutions, but for the next gen- eration with bigger bandwidth and higher fre- quency, we have to go to other materials, and these have to be qualified. Matties: Are you looking at the cleaning stan- dards and changing the requirements as you talk about the electrochemical migration? Klein: Cleaning is always discussed because cleaning is quite difficult. e problem is that up to now nobody can offer the perfect clean- ing solution. Aer assembly, some of the sol- der paste residuals could stay in small gaps be- low the QFPs and other components. at is very difficult to clean perfectly. Regarding the bare PCB itself we do not really see a prob- lem. What is still on the board aer the PCB production will evaporate during first reflow. ereaer, it depends on the use case. If a de- signer makes the housing of the PCB quite tight and uses a pressure compensation ele- ment, the warm and humid air does not get di- rectly onto the PCB itself, and dewing can be avoided. erefore, we must be really careful in designing our units that dewing of water will not happen. Cleaning has not been a big topic because we use a specific design of our control units to avoid this dewing. Christian Klein