I'm seeking new transparencies

Discussion in 'General Electronics Chat' started by mik3ca, May 9, 2008.

  1. mik3ca

    Thread Starter Active Member

    Feb 11, 2007
    I got fedup with the latest board.

    It seems that the tracks and everything were aligned perfectly, and that the board was about to work, until I found out later (after soldering most joints) that 1/2 the tracks are cracked to the point where there is no continuous conductivity. I tried using solder to cover the cracks, and that failed.

    I'm beginning to think it is the fault of the transparency. I bought 10 of them for 30 cents from grand and toy. When I ran it through the laser printer the image seems clear, but then I had a closer look, and at the time when I did the circuit, the image appeared clear.

    Now when I had an extremely close look, I could see random transparent dots throughout my artwork.

    I tried to shake the toner and put it back in, and tried printing again, and it made no difference.

    I'm starting to not trust the transparencies because when I tried printing on standard paper, the image is very sharp and excellent (without random transparent dots).

    and when I bought the transparencies, I specifically said for a laser printer (which is what i was using).

    Next time when I order transparencies, is there anything special I should say when I order them? Maybe there are certain laser transparencies that work better than others.
  2. SgtWookie


    Jul 17, 2007
    I'm afraid you're going to have a heck of a time trying to get precision out of a laser-printed transparency. The heat from the fuser will cause the plastic to distort.

    Read this person's experience similar to yours:

    Do you have an inkjet printer handy? You won't have nearly those kinds of problems with an inkjet.

    In the meantime, if you don't have an inkjet - you could try Tom Goot's method of direct ink transfer rather than photographic. You'll need special photopaper, and don't try to use other than specified.

    However, you will likely wind up with similar results as you're having now.

    You won't have much luck trying to bridge the gaps in your board with just solder, as you've already discovered. However, you can use some buss wire (or trimmed leads from components) to bridge the gap; solder it down close to the defective run. Tin/lead solder has about 5x the resistance of copper. Having the buss wire/trimmed lead will help reduce that impact.
    Last edited: May 9, 2008
  3. Papabravo


    Feb 24, 2006
    I guess you get what you pay for. That's why I think the experts in board fab are stone cold bargain.
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008

    What brand of transparency are you using for the inkjet photo method?

    I have used the positive-resist photo method for more than 10 years with Pictorico (formerly AGA, now Mitsubishi) Premium OHP Transparency Film and have been very satisfied with the results.

    I have now spent more than a week looking for it and cannot find it anywhere in Cleveland. I can buy directly from Mitsubishi, the price is almost $3.50 per sheet, and Mitsubishi hasn't answered e-mails on the details of how to buy or to confirm it is the same stuff. No idea on delivery, but based on the poor communication, the prospects don't seem bright. The newer, cheaper "UltraPremium" is UV opaque, which is not good.

    Last edited: May 9, 2008
  5. SgtWookie


    Jul 17, 2007
    Hi John,
    Actually, I've tried multiple times using various techniques with my high-time HP 4050TN laserprinter. It works wonderfully for "normal" text-type printouts on paper, but even printing photographs leaves a good bit to be desired. I blame this on it having nearly 100,000 sheets of paper through it, rather than the design. I'm dubious about spending $300 for the service kit.

    I have not yet tried the inkjet photo transparency method, even though I do have a low-time hi-res color inkjet - and I even have a couple of photo-ready boards kicking around.

    What I really want to do is build a small CNC mill so that I don't have to deal with all of the heinous chemicals one has to handle with other methods - basically, it's a huge shortcut. With a CNC mill, I wouldn't have to worry about all that - and drilling all of the holes that's problematic when one's vision is less than it used to be.

    Oh, and there's nothing to the "old wive's tale" rumor - vision is most definitely the first thing to go ;)
  6. Wendy


    Mar 24, 2008
    Amen bro, you should trying working with microscopic wire sometime. If you do go the CNC mill, I'd like to hear the details, for similar reasons.
  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    Well, I agree on the CNC. I have had that in my mind for years (I have a full-size Bridgeport and British-equivalent Hardinge lathe). It seems everyone at the hobby level is using steppers, but my gut tells me a servo has got to be better. Someday...
  8. SgtWookie


    Jul 17, 2007
    Well, a servo tends to eliminate certain problems - but I digress, and we're getting quite O.T.

    This is Mik3ca's topic; he has a very specific situation that he hasn't further expounded upon. It would be very unfair to him (and contrary to the Forum policies) to hijack his thread.

    We need to stick to the rules, and the topic here.

    I would very much like to contribute something useful to this thread, but I'm afraid I can't - so I must withdraw.

    I hope that someone CAN help Mik3ca with his current dilemma.

    That's the whole purpose of these forums.
  9. beenthere

    Retired Moderator

    Apr 20, 2004
    Just to put in 2 cents, I have been using 3M transparencies and an HP Laserjet 4 for years with excellent results. Line reso down to 8 mills. Until it died, I also got comparable results from a Lexmark C710.

    It may be worth using better material. It's hard to be sure, as my CAD is out of the '80s and handles printer output very differently.