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. -- I used to like HP before computers, and once I even liked Compaq, but I liked DEC better than HP and Compaq put together.