I think I'll drop by work and pick up one of the two 1.3 meter wide plotters we got in last week. They are used, and just lying around. Time for me to play a bit. Err, inbetween my project work that is... Kyrre ----- Original Message ----- From: "Olin Lathrop" To: Sent: Wednesday, November 13, 2002 6:20 PM Subject: Re: [EE]: Printer to PCB? > > When I played with this kind of thing on an old HP plotter, the > recommended > > resist pen ink was a staedler red felt marker. I replaced the felt > soaked > > core of the standard plotter pens with a scavanged staedler pen. You > can > > get a bottle of the same ink (although it's special order around here.). > > Might try to see if it will work in an ink jet nozzle. > > Back in 1980 I was right out of school and working for HP. I wanted a way > to make my own circuit boards for personal projects like you guys are > talking about. I even wrote a simple layout program on the desktop > computer I had. You entered coordinates for net points in a text file and > it would compute the tracks and mark whatever it couldn't route. The > problem was how to get the information out of the computer onto a circuit > board. > > There was a pen plotter available that could be hooked to the computer, so > I programmed it to draw filled areas by using a raster pattern. At first > I just had it draw onto a piece of paper, then converted that to a > Kodalith negative in the darkroom, then used that to expose boards. At > the time there was photoresist available that came in two parts. It ended > up being a thick greenish liquid that you painted on the copper then let > it dry. I think it was called "Resolve" or something like that. It was > not lacquer based as everything I've seen since then. After exposing the > board, you rinsed away the unexposed areas with plain water, then baked > the board to cure the remaining stuff onto the copper, then etched > normally. > > This process worked OK, but there were problems. The worst one was that > it would use up one or more of the little felt tip plotter pens per board. > I tried to fix that by cutting the top off one of them and manully filling > it with ink before a run. That helped, but it made large blotces in the > beginning, and needed refill steps along the way. Then I modified a > "liquid ink" pen mount on the plotter. These have no ball point or felt > tip, just a cappillary with a tube to an ink reservoir. The cappillary is > thin enough so that the ink doesn't come pouring out until the bubble > touches the paper. This worked much better, but was quite a mess to use > and clean. > > Then I began experimenting with using dark ink and writing directly onto > the photoresist layer. That sortof worked, but the ink apparently didn't > block the light that well or otherwised messed up the photoresist. Then I > tried "writing" a resist layer directly to the copper using the liquid ink > pen. I changed jobs and lost use of the equipment before I found an ink > that would both adhere to copper and stay there during the etching > process. > > If you guys really want to try direct writing resist onto a copper board, > I suggest looking into a liquid ink pen driven by a plotter. Liquid ink > pens will take just about any ink, and can deliver large quantities of it > unlike any other pen. It will be hard enough to find a suitable ink > without also requiring it to work in an inkjet printhead that is finely > tuned for a specific type of ink. > > Since I was experimenting with this 22 years ago, I've noticed some > substances that might be worth a try as ink. One of these is a liquid > plastic you can get in toy stores. I think it's meant to immerse wire > loops in, then pull them out and let the "soap bubble" film dry into a > plastic membrane. I bet this stuff stands up to etchant, but I don't know > how well it might adhere to copper. I'm sure it is way too gloppy for an > injet head. The next thing I was going to try was polyurethane paint, but > never got to it. > > > ***************************************************************** > Embed Inc, embedded system specialists in Littleton Massachusetts > (978) 742-9014, http://www.embedinc.com > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads