What are PCBs usually made of? I have experience with multilayer circuits and the process of making them, but I mainly worked with flexible polyamides, not boards. The company I worked for used fiberglass (G-10?) as stiffener material, and I could assume PCBs are typically made with a fiberglass material, but I'd rather know. >>> steveg at transition.com 11/08/01 01:39PM >>> The color of a PCB has absolutely nothing to do with quality. Most PCBs are green because the solder mask is green. Solder mask is the coating on the outside of the board that keeps solder from sticking to everything when the assembly goes through a solder wave (thru hole), or keeps solder paste from oozing everywhere when the assembly goes through the IR process (surface mount). We do some gigbit designs with buried traces, controlled impedance some of which were 8 layers, some other designs were 14 layers. They were all green. -----Original Message----- From: phil at rephil.org [mailto:phil at rephil.org] On Thu, Nov 08, 2001 at 10:02:15AM -0600, jima wrote: > I had the same response once when someone told me the motherboard he > bought was blue (as opposed to green). He didn't get my line of > questioning. "WHAT IS THE TECHNICAL SIGNIFICANCE OF THE COLOR > BLUE!?!?" Seems like a pretty simple question to me. :) There may be a little significance, but the color is just a by-product if that is the case. Many cheap (consumer electronics) PCB's are green, because they use a cheaper board, and only one sided thru-holes. Often times, blue boards were a sign of a better board (I forget the material) with a better (epoxy?) finish and dual sided / plated thru holes. [1] Also, I recall seeing blue typically on multilayer PCBs, i.e., 3 or 4 circuit layers sandwiched together, and in a really heavy RF application (like a GHz processor) might even have an internal ground plane. I don't recall seeing green for "real" PCBs. [1] Thru-holes are the holes in which the component leads go (though many things are surface mount these days.) A one-sided thru hole only has a pad on one side of the board, while a plated thru-hole has contact metal plated on the inside of the hole. When the solder joint is made, it's much more robust, and a cracked solder pad on one side of the board won't cause bad connections as easily.