Issue link: https://iconnect007.uberflip.com/i/1248324
62 PCB007 MAGAZINE I MAY 2020 fully tested, there are also no yield surprises at the end of the manufacturing process, which could cause critical delays to the end customer. Lastly, these methods allow for our customers to have the ability to utilize generic mother- boards with specialized daughter cards, which can reduce cost and time to market. Since we have been using these intercon- nects, we thought that we needed a better understanding of how they might electrically and mechanically affect our customers' end products. In light of this, we decided to pro- cess test vehicles to electrically characterize each of these interconnect types. This would allow us to better suggest which type to utilize based upon our customers' product attributes and expectations. In our testing, we decided to use a high aspect ratio through via as the baseline and compare it to a sintered via, vias connected through a Samtec Z-Ray© connector, Plastronics connector, a reflowed solder ball, and an ISC International elastomer. Test Vehicle and Via Structure Types Test vehicle design was completed by Probe Test Solutions. The control in our study was de- signed at 0.160" thickness PCB with a 0.006" mechanical PTH (27:1 aspect ratio). This via was connected to a 50-ohm impedance con- trolled outer layer trace on the top and bottom surface. Each of these traces was then connect- ed to an RF connector (Figures 1 and 2). This via structure represents traditional through- hole manufacturing processes and should pro- vide the best electrical performance. It should be noted that our testing simulation of the de- sign (including via impedance) was waived as this test was to be just a comparison of the in- terconnect methods. The remaining test vehicles were designed as two independent 0.080" PCBs, each with a 0.006" mechanical PTH. The top PCB would have the 50-ohm impedance controlled trace on the top layer and a pads only layer on the bottom. The bottom PCB would be a mirror image with the pads only layer on the top lay- er and the 50-ohm impedance controlled trace on the bottom layer. Each of these was then connected to its partner through our various methods (sintering, Samtec Z-Ray© connec- tor, Plastronics connector, solder ball reflowed, and an ISC International elastomer). For some further background on each of the intercon- nect types included, there are descriptions and some cross-section views in the following paragraphs. Figure 1: Gerber layout of the top and bottom layer of test vehicle. Figure 2: Actual through-hole test vehicle.