On Thu, Nov 08, 2001 at 01:39:49PM -0600, Steve Grobe wrote: > The color of a PCB has absolutely nothing to do with quality. Didn't mean to infer causality! I can't remember PCB makers now (it's been too long), but was just trying to say that there used to be a correlation -- the good boards tended to be coated in blue, the cheapies tended to be coated in green. I've seen 'em other ways, too. Either way, flex them hard enough and you can break them. ;) Phil > 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] > Sent: Thursday, November 08, 2001 11:32 AM > To: tclug-list at mn-linux.org > Subject: Re: [TCLUG] Aww yeah, new box > > > 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. > _______________________________________________ > Twin Cities Linux Users Group Mailing List - Minneapolis/St. Paul, Minnesota > http://www.mn-linux.org > tclug-list at mn-linux.org > https://mailman.mn-linux.org/mailman/listinfo/tclug-list > _______________________________________________ > Twin Cities Linux Users Group Mailing List - Minneapolis/St. Paul, Minnesota > http://www.mn-linux.org > tclug-list at mn-linux.org > https://mailman.mn-linux.org/mailman/listinfo/tclug-list -- I used to like HP before computers, and once I even liked Compaq, but I liked DEC better than HP and Compaq put together.