PCB making

Discussion in 'General Electronics Chat' started by TBayBoy, Aug 17, 2011.

  1. TBayBoy

    Thread Starter Member

    May 25, 2011
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    I've seen videos of PCB's made by photo resist, heat transfer, and CNC. Is there advantages / disadvantages for each based on what the final board is used for? eg: a power supply use photo resist, sound amplifier use cnc, etc.
     
  2. TBayBoy

    Thread Starter Member

    May 25, 2011
    148
    19
    I think I stumped everyone :)
     
  3. #12

    Expert

    Nov 30, 2010
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    Any method that gets the copper in the right place and not in the wrong place is equally good as far as I can tell. I've gone to Philadelphia in a car, on a bus, and on a train. They all got me to Philadelphia.

    I've only used photo resist and resist pens to make circuit boards, but the same board by any other method would work as well.
     
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  4. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    I think that the first reaction of many was, "No, it doesn't matter," but on further reflection realized they had never considered the question and that one method might actually be better for certain applications, so they didn't post an answer for fear of being contradicted. At least that was the case with me.

    The only reasons that I can think of that might make one method better than another is that the complexity and small pad/track size of some small/complex circuits might not lend themselves to less precise and/or slower fabrication methods, e.g., CNC. However, I think that once a PCB is successfully fabricated, it makes no difference to the circuit or components what the fabrication method was.
     
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  5. Johnny Nelson

    New Member

    Aug 19, 2011
    5
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    The difference I guess is mostly how difficult or easy it is to make and how many pcs you need to make. If its just protptyping then it would be silly to set it up for a high quantity process.
     
  6. strantor

    AAC Fanatic!

    Oct 3, 2010
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    I did hours & hours of research into PCB making (mainly CNC vs chemical resist) but only ever made 1 PCB and it sucked. So, I will summarize what I read but don't take it as first hand experience. CNC is the "best" for a few reasons: 1.Repeatability - you can make umpteen million copies of the same board flawlessly. 2. precision - you can make traces narrower than what's achievable by chemical resist methods. 3. ease - just draw it up in a CAD program and it goes straight to the PCB. The downside is you need to have/make a CNC machine and learn how to use it.
    Chemical resist (liquid etchand) whether by hand-drawn resist or toner transfer is the "worst" - messy, must make the traces wider to acommodate a little bit of "bleed-over", could take all day to make a few boards. It's nearly impossible to make PCBs for the tiny SMD stuff with this method (from what I read)
    Photo resist I didn't research much, but the quality looked somewhere between chemical resist and CNC. Takes a bunch of equipment.

    Hobbyists usually go with chemical resist because all you need is a sharpie or a laser printer and some etchant. you can make decent PCBs this way but it is a handful. this is the way I tried but my PCB sucked. I could have gotten better at it, but I got side tracked with other things and the next thing I know it's a year later and my laser printer is in the bottom corner of the closte in the guest bedroom under a pile of unloved sheets. I think Bill Marsden has a pretty good thread on this method, search for "how I make PCBs"
     
  7. #12

    Expert

    Nov 30, 2010
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    Being disagreeable right now.
    I made multiple surface mount (0603) circuit boards with a transparent plastic that had photo's of the circuit traces, and sunlight, and it worked just fine on the first try.
    Point is, chemical etching can work properly for surface mount pads, even if you've never done it before.
     
  8. Kingsparks

    Member

    May 17, 2011
    118
    5
    Just to be different, I have made a few boards using an adhesives backed copper tape made by 3M

    Could cut the lands with a straight edge, holes with a leather punch, (Used the punched out hole then pierced it.)

    It was time consuming and tedious but worked fine. It was also a simple circuit and the only way I could get a PCB done at that time. Mostly I do point to point wiring.

    I have also used the etching method. Okay but messy.

    Point is, it all worked.
     
  9. Barnaby Walters

    Member

    Mar 2, 2011
    103
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    I draw circuits out by hand (usually after planning them in PCB design app), and then etch with ferric chloride. It's not really very messy if you're careful, and it's pretty straightforward if you're willing to do a bit of research and not take it too quickly.

    It's not great for multiple runs (actually, terrible) but I've made several successful boards containing a mixture of TH and SMD components.

    Thanks,
    Barnaby
     
  10. Wendy

    Moderator

    Mar 24, 2008
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    Chemical is the norm, and is extremely repeatable. It took some trial and error on my part, and the least repeatable part of PCB fabrication for me is drilling the holes.

    Actually, I suspect for really tight patterns, such as a 20 pin IDC cable, you would have problems machining the small spaces that chemicals won't.

    How I make PCBs

    The trial and error can be a pain though.
     
  11. HarveyH42

    Active Member

    Jul 22, 2007
    425
    5
    I like the toner transfer method, it's quickest, efficient, boards come out well enough for hobby circuits, and quite repeatable. There were a few problems at first, but once you learn past, it's quick and simple. Refilled toner cartridges are bad, least the one time I tried to save a few bucks. Looks fine on paper, great way to save office money, but leaves hideous holes. Hand iron, big hassle, how long to iron, how much pressure, how hot... Never got the knack for it, bought a hot laminator, and eliminated the problems, not to mention the transfer is done in seconds. Paper... which brand photo paper, plain paper, magazine paper, all of which leave pulp, that needs to be cleaned up, and maybe a little touch up with a marker. Went with Pulsar paper, and haven't had any need to try anything else. Set the printer to card stock, density on the highest level, and I get good solid traces, unless I'm careless with fingerprints on the copper. The Pulsar paper releases quick and clean, in just a few seconds under running water, and ready to etch. The etching and drilling are the hardest part of the process. Little sloppy and careless, by nature, so I've got to use extra care and attention. Have to stay focused on the etching, and not get side-tracked for the 10 minutes or so, which is really hard.
     
  12. MrChips

    Moderator

    Oct 2, 2009
    12,451
    3,370
    I have made many high quality pcbs using photo resist, but then I had the right equipment to do so. Now I send them out to shops that offer special pricing for prototype service.

    Since a lot of the analog work I do these days use SMD components, I make prototype boards by hand. I use double sided circuit board and leave copper on the bottom side as a full ground plane. I cut narrow channels on the component side creating islands of copper for SOIC chips, R and C. The channels are 0.5-1mm wide and I peel off the copper as if you are rolling up sod off the ground. I can get top quality signal performance as good as a properly made pcb.

    Another solution is to use a CNC machine to mill out the copper.
     
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