The creation of double-sided board is more challenging than one-sided board. The key good reasons are as follows: In short, the 4-layer board has an inner layer. Concerning the process, some traces are going to be etched with the inner layer shaped by lamination. The double-sided board is often drilled https://four-layertin-sprayingmod05837.thekatyblog.com/30317547/5-simple-techniques-for-12-layer-module-pcb