Issue link: https://iconnect007.uberflip.com/i/992528
JUNE 2018 I PCB007 MAGAZINE 75 downloaded the design file. A schematic of the design is shown in Figure 2. Test panels were fabricated as follows: Stress test (IST) coupon containing plated through-hole technology on a 5.0" (126.9 mm) X 0.7" (17.8 mm) cou- pon with a total thick- ness up to and not ex- ceeding 0.125" (3.2 mm) and limited to a mini- mum of six layers. This coupon is designed on two independent grid sizes, 0.040" (1 mm) and 0.080" (2 mm). The maximum hole/pad size for the .040" (1 mm) grid is 0.015" (.38 mm) drilled and pad size is 0.028" (.7 mm), on both power and sense circuits. The maximum hole/pad size for the .080" (2 mm) grid is .056" (1.42 mm) drilled and pad size is .068" (1.73 mm), on the power circuit. The test vehicles as de- scribed here were built in-house by the fabrica- Figure 2: IST coupon GT40800D. (Source: PWB Interconnect Solutions) Figure 3: Resistance measurements for the two indepen- dent circuits. The "P" is the power circuit—where the direct heat is transferred through the post interconnect and measures change in resistance through the post. The "S" circuit measures the resistance change through the PTH or barrel of the hole. Results for the test vehicle with previous electroless copper. Figure 4: Resistance measurements for the two independent circuits. The "P" is the power circuit—where the direct heat is transferred through the post interconnect and measures change in resistance through the post. The "S" circuit measures the resistance change through the PTH or barrel of the hole. Results for the test vehicle with newer electroless copper.