see my pcb ploter at www.geocities.com\pancary ----- Original Message ----- From: Hans Wedemeyer <hans@...> To: <Homebrew_PCBs@yahoogroups.com> Sent: Sunday, May 18, 2003 3:52 PM Subject: Re: [Homebrew_PCBs] How I make my PCBs > Mike, > H'mm as I have pretty good looking boards and can do 5 mil all day long > ! > > Here's an example http://hans-w.com/pcb_harwin_rivets.jpg > > I've only been using Round Bulbs of various types for about 27 > years...... > I like the short exposure time and never have noticed the effect you > menitoned, my largest board size > is about 6"X7" and it exposed uniformly. > > Just what is it about my boards that you think would make them any > better ? Please explain ! > > Hans Wedemeyer > > > Mike Putnam wrote: > > > Hans, > > I looked at the picture of your UV exposure setup. I just wanted to > > comment > > that I would never use the round bulb. Use the florescent tubes and > > your > > results will be better. I have found that the round bulb tends to give > > more > > exposure in the center than at the outer edges. Even more apparent > > with > > larger boards. This is the reason all exposure units sold on the > > market use > > the florescent tube. You can compensate somewhat by having the bulb > > not so > > close, but this just increases your exposure time. The other bad thing > > about > > the round bulb is the heat. This will actually get in the way of your > > process, depending upon what type of photo etch you are using. I am > > trying > > to recall if it was a problem caused to the developer or if it was a > > consistency problem in the exposure. Nevertheless, I found it to be a > > problem several years back. If you modify your design to use the > > florescent > > bulbs, you will notice a marked difference in detail as well as less > > exposure time needed. > > -Mike > > > > ----- Original Message ----- > > From: "Hans Wedemeyer" <hans@...> > > To: <Homebrew_PCBs@yahoogroups.com> > > Sent: Sunday, May 18, 2003 7:41 AM > > Subject: Re: [Homebrew_PCBs] How I make my PCBs > > > > > > > Leon, > > > good advice except for Easy-PC.... > > > I spent full price on that program and found I wasted my money. > > > Here's what I think of Easy-PC > > > http://hans-w.com/ezpcbugs.html > > > > > > I moved on to EAGLE and have been happy with it. It's STABLE does > > not > > > blow up cause me to lose work=time=money. > > > > > > A limited version of EAGLE is available for Free, it is limited to > > two > > > sided board and size check it out at > > > http://www.cadsoftusa.com > > > EAGLE has a VAST library of part and users add parts all the time. > > > Compared EAGLE parts Library to to Easy-PC several 1000 to 1 > > > > > > I put Easy-PC up for sale on eBay but none wanted it. In fact I put > > my > > > entire collection of Numberone product in the same auction > > > Filter program, Easy-PC for DOS and for Windows and the digital > > > simulator Pulsar. INo one reached my minimum Price of $200 ! It's > > still > > > here in a box onthe floor, I think I'll use the disks and CD's for > > > target practice sometime... > > > > > > Here's one thing that is not (was not)( they may have fixed it by > > now) > > > possible to do with Easy-PC for Wndows, in a situation where top and > > > > > bottom layers have parallel tracks sections that overlap, and a > > whole > > > bunch of closely spaced via's or other pads, it is not possible to > > put > > > the cursor on the trace/pad that I want for move/edit. It just snaps > > to > > > the nearest and of course that is not handy at all ! I can turn snap > > off > > > but that is not what it's all about. > > > EAGLE allows ANY pad/trace on any layer to be individually selected > > even > > > if they are overlapping. > > > > > > Pulsonix used to look like Easy-PC, I think they are the same > > bunch... > > > Although Pulsonix used to give the schematic editor away for free, > > the > > > PCB layout part is high $$$$ ! That's much like saying "this car is > > > > > free, but the special wheel cost $20,000 each " > > > > > > I'll get off my soap boix now... > > > > > > I make double side board all the time. I used to do it the way you > > > mentioned, and even wrote a program for my CNC mill to compensate > > for > > > alignment problems. > > > I found a better way by printing on transparencies and then aligning > > > > > them visually, then stapling them together. Then slide the board in > > > between the transparencies and sandwich the whole lot between two > > plates > > > of glass, and place the sandwich between two lamps > > > http://hans-w.com/setupforexposure.jpg > > > and > > > http://hans-w.com/twolampexposure.jpg > > > Credit for this sandwich idea goes to > > > http://www.electricstuff.co.uk/pcbs.html > > > > > > Alignment between top and bottom is good. Perhaps the greatest > > problem > > > I've run into is the HP LaserJet making different print sizes when I > > > > > mirror the one side. > > > I used to worry about getting the printed side of the transparency > > close > > > to the PCB, after testing with 5 mil lines I decided there is NO > > need to > > > mirror. Using the exposure as I how in my photo it allows me to do 5 > > mil > > > lines all day everyday. > > > > > > Thanks for all the tips. > > > Best Regards > > > Hans Wedemeyer > > > > > > > > > Leon Heller wrote: > > > > > > > I've been making my own PCBs at home for about 40 years, starting > > by > > > > painting the pattern onto single-sided PCB material using a fine > > > > paintbrush and cellulose paint, with ferric chloride or ammonium > > > > persulphate etchant. I used 0.1" graph paper for designing the > > layout > > > > then marked the holes with a centre punch through the paper onto > > the > > > > copper surface. I even made a couple of double-sided PCBs using > > this > > > > technique, by masking off one side, etching the other side, > > drilling > > > > it, > > > > and using the drill holes as a guide when painting on the resist > > on > > > > the > > > > second side. I then masked off the first side with tape to etch > > the > > > > second side. > > > > > > > > When low-cost CAD software became available (I used Easy-PC from > > > > Number > > > > One Systems for years) I progressed to printing 2:1 artwork on a > > dot > > > > matrix printer. I then got a local litho platemaking company to > > > > produce > > > > a 1:1 positive transparency that I used with a home-made UV > > exposure > > > > unit and resist-coated PCB material. When I got an ink jet printer > > I > > > > found that I could get reasonable results by printing 1:1 artwork > > onto > > > > > > > > tracing paper. > > > > > > > > I now use an old LaserJet IIIp I picked up very cheaply to print > > 1:1 > > > > onto LaserStar film and expose the PCBs in a home-made UV exposure > > > > > > unit. > > > > I sometimes use tracing paper (nice and cheap), but find that I > > get > > > > better results from the LaserStar film. The CAD software I use is > > > > Pulsonix, a professional package out of the same stable as > > Easy-PC. I > > > > regularly use 12/12 design rules, occasionally going down to 10 > > mils > > > > if > > > > I need to route tracks between IC pads. Rather than conventional > > > > positive-resist FR4 PCB material, I usually use something called > > > > FPC-16 > > > > which consists of a sandwich of compressed paper between thin > > layers > > > > of > > > > fibreglass. It's cheaper than FR4 and much easier to cut and > > drill. > > > > It's > > > > available from Mega Electronics, as is the LaserStar film. > > > > > > > > Etching is in ferric chloride. I place the etchant in a small > > plastic > > > > food container inside a larger container half-filled with hot > > water > > > > and > > > > continuously agitate the etchant manually by rocking the > > container. > > > > Etching typically takes 5-10 minutes. > > > > > > > > I'm quite pleased with the results. I intend to experiment with > > > > double-sided boards by making a UV exposure unit that can expose > > both > > > > sides of the PCB simultaneously. With a better printer and vacuum > > on > > > > the > > > > UV exposure unit I think I could get 8 mil tracks quite reliably. > > I've > > > > > > > > heard of other people managing it at home. > > > > > > > > Here is an example of one of my PCBs: > > > > > > > > http://www.geocities.com/leon_heller/pcb.html > > > > > > > > I often use the Pulsonix copper pour facility for this type of > > board, > > > > as > > > > it makes the routing easier. Cross-hatching is better with a laser > > > > > > printer, as they don't tend to print large black areas very well. > > > > > > > > Links: > > > > > > > > Mega Electronics: http://www.megaelect.demon.co.uk/ > > > > Number One Systems: http://www.numberone.com/ > > > > Pulsonix: http://www.pulsonix.com/ > > > > > > > > Leon > > > > -- > > > > Leon Heller, G1HSM > > > > leon_heller@... > > > > http://www.geocities.com/leon_heller > > > > > > > > Yahoo! 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Message
Re: [Homebrew_PCBs] How I make my PCBs
2003-05-19 by Pancary