Issue link: https://iconnect007.uberflip.com/i/1129312
36 PCB007 MAGAZINE I JUNE 2019 Figure 3 is another example of a double-sid- ed flexible circuit. You can see from the photo that this design also uses a polyimide stiffen- er. In this case, the stiffener is functioning as a support for that component area, adding a bit of thickness. The other interesting thing to note about this sample is the use of pressure sensitive adhesive (PSA). This is something that doesn't really make its way into design guideline discussions but is commonly used to mount the flex inside of the unit either to be sure it remains in place through the life of the product or to help anchor a section that is go- ing to have a lot of flexing in end use. This is one of those items that calls for imagination. Figures 4 and 5 are images of a double-sided flex that does an excellent job of taking advan- tages of packaging benefits of a flexible circuit. The shape of a flex interconnect truly allows for creativity and imagination. In Figure 4, you can imagine how this will simply drop into the unit, eliminating wire and assembly. In Figure 5, you can also imagine how that tail breaks off from the main flex area. What you can't see is the PSA being used to guide and secure that during installation. Figure 6 shows an example of a simple rigid- flex. In this case, the FR-4 stiffeners have plat- Figure 3. Figure 4. Figure 5.