Issue link: https://iconnect007.uberflip.com/i/1350598
26 PCB007 MAGAZINE I MARCH 2021 Q: From a PCB fabricator's point of view, what are the key capabilities required for each of these categories? A: Here we see a clear separa- tion into the various catego- ries or applications. Let me start with the need for elec- trification; this splits into the controlling functions and the power units. e vehicle con- trol units (VCUs) are more advanced computers that have to deal with much data for giving signals to the pow- er controls. A hybrid car wknows when the next traffic light or sharp corner will come and reduces the power before the driver even rec- ognizes the situation. e powertrain includes chargers, DC/DC converters, inverters, power boards, or DC breakers for the electric engine. Hybrid cars are mainly designed with 48V and have significant current on the board to real- ize driving or charging power. Hence, a signifi- cant heat load and thermal (heat) management method is utilized in the PCB designs. ere are various concepts to get the heat out. ese include utilizing lots of copper in the board in the form of thick copper layers up to 12 ounces (16.2 mils/411 µm), increasing copper thick- ness in selected vias, copper coins, inlays, or busbars. Other concepts include coatings or glues with increased thermal conductivity. ese can be applied on the board or used as a connection to the housing or cooling element. e designer must consider the significant in- creases in line widths and spaces required for heavy copper layers. ey are oen le on in- ternal layers only to maintain connections to fine-pitch surface mount devices soldered to the finished PCB. Looking at the fully electrified cars, we need solutions to deal with the high current and the heat and high voltage. We are now looking at voltage levels of 450V-470V, but we see appli- cations with 800V, 1000V, or even 1500V as future de- mand. At these higher volt- age levels, you will see dif- ferent failure modes in the boards. e board's electri- cal field strength may reach values where local discharg- es may damage or carbon- ize the resin and start an av- alanche of these local dis- charges creating a high-ohm short. Solving this chal- lenge and creating highly re- liable systems means thor- ough reviews of the PCB de- sign, stackup, materials, manufacturing meth- ods, and location. Additionally, cleanliness is an essential factor to avoid introducing foreign materials/particles in the laminate and man- ufacturing processes, which could be the ori- gin of such a discharge. Materials are a key fac- tor, and we see considerable differences in the performance of different laminates. Customers benefit from collaborative efforts with experi- enced Tier-1 PCB fabricators. Connectivity, infotainment, and comput- ers for autonomous driving enablement are pushing HDI and advanced HDI technology forward. e chipsets are using high-density BGAs, which require multiple laminated lay- ers to get the signals routed. Lines and spac- es are pushing sub 100 mm/100 mm (4 mil/4 mil). Pad diameters are shrinking, making it a challenge to manufacture these boards accord- ing to IPC Class 3, and oen requires design trade-off discussions. To run such products, fabricators have to invest in state-of-the-art production equipment. e most prominent element of the ADAS category is the radar and LiDAR sensors. A decade ago, these sen- sors were mainly used in the aerospace and de- fense (A&D) industry and for big equipment pieces. TTM Technologies has a long legacy of being one of the largest suppliers to the A&D sector. We can leverage our expertise to sup- Walter Olbrich