Hi, My customer is curious as to what would cost more a 4 layer board or a six layer board. Here are the details: Board has 1 gnd layer an 1 vcc layer and is primarily surface mount and a digital circuit without any critical paths. These will remain constant. The board was autorouted for both a six layer version and a four layer version, so here is the difference of 2 signal layers or 4 signal layers . The 4 layer was routed to 96% and 2500+ vias and the six layer routed to 100% with 1450+ vias. We all can surmise that the six layer version will be more reliable in the long run. I am told that the cost is drilling alone is about a $100 difference per board. Can any body help with the cost analysis? Thanks in advance, Scott Shepard Interactive Design Solutions also at [log in to unmask]