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24 PCB007 MAGAZINE I SEPTEMBER 2025 low CTE makes it an excellent BT (bismaleimide tri- azine) alternative. Whether you are exploring or- ganic substrate builds or need next-level HDI, Ar- lon 86HP is a highly manufacturable solution with great breadth in its potential usage, with many ap- plications yet to be explored. EM-892K/K2, fully commer- cialized for mass produ-ction, is an extreme low-loss system that processes like FR-4, but dips into the 0.0010 Df space. With a Dk's ranging from 2.80 to 3.00, EM-892, with K or K2 glass, makes very high-end, ex- tremely low-loss applications feasible, which include AI serv- ers, high-speed networks, and demanding RF designs. It is well-suited for hybrid (mixed material) builds and has very low CTE for high reliability. EMC and Arlon offer a broad range of PCB materials for the entire range of PCB technology. We are pleased to have these products to support our customers and complement our robust service and supply model. PCB007 Chris Hunrath is vice president of technology at Insulectro. F i g u re 3 : C ro s s - s e ct i o n of ex t re m e l y a d va n c e d P C B st a c k u p u s i n g m ate r i a l f ro m t h e E M -8 9 2 K / K 2 s u i te. ▼ Material Construction Stackups A printed circuit board stackup refers to the material construction of the PCB, including core dielectrics, prepreg di- electrics, and copper sheets. Many fac- tors need to be considered when devel- oping a stackup, including overall thick- ness restrictions, circuit width and spac- ing, and impedance values required. The ASC design guidelines presented earlier, along with frequent engagement with your PCB fabricator, are always encouraged to select the optimum solution for any particular design. Design success guidelines: • Design multilayer boards with an even number of layers • If specifying the dielectric thickness when, for example, it may be required for impedance reasons, the dimen- sions should be selected from available core or pre- preg thicknesses • Dielectric thicknesses made up of prepreg depend on the type or combination of suitable prepreg and achievable dimensions and tolerances • It is beneficial to discuss special dielectric require- ments during the design stage with your PCB vendor, if possible • If the prepreg layer thickness/total dielectric thickness for the given layer is greater than 0.016" (0.406 mm) use filler/dummy cores (cores with no copper) to achieve the total layer thickness Outer layer circuitry: Circuit area and distribution be- tween the front and back of the board should be balanced as closely as possible. The addition of plating thieving to low pattern density areas on the external plane area may be considered. Continue reading... The Printed Circuit Designer's Guide to... DFM Essentials, Chapter 4 By Anaya Vardya, American Standard Circuits / ASC Sunstone Circuits