I am rather new to making printed circuit boards. I have had about 7 unsuccessful tries. I used the method of printing a positive on a transparent film, exposing the cladded board and with the film on it to UV light and then developing and etching. While about three of the boards were somewhat "manageable", they had broken traces on them.
I'd like to ask: what would we recommend as the "best" method for making PCBs for private users (i.e. not on a commercial scale)... Then, any advice for a starter is welcome.
"wale" schreef in bericht news: snipped-for-privacy@b79g2000hse.googlegroups.com...
Look at:
formatting link
I my experience, when using the toner transfer method, you need a laser printer that leaves a real thick sheet of toner on the traces. This method worked great for me as long as I had excess to such a printer.
When using the photo method the positive needs to be real pitch black. Exposure time needs to be found by experiment. Different brands of photo sensitive PCB require different exposure times.
"Best" method 1, of the modern era - not so fast, but good quality, not very expensive, no mess, can even have soldermask and screenprint or more than 2 layers - one of the cheap board houses.
"Best" method 2 - resist ink pen right on the board - not great for fine detail, but easy - less steps to frig up.
"Best" method 3 - get a better transparency, and pay attention to details.
A graphic arts house might be able to print your file on a photoplotter or some other method that will get you a solid black transparency. One probable cause for bad traces is bad toner coverage on your transparency
- examine it with a magnifying glass against strong light. The blacks need to be black, without pinholes. Most laserprinters leave pinholes. You can ink over things with a black or red marker as a stop-gap.
Clamp the board and the transparency tightly together - any loss of contact will also cause broken traces, as the light comes around the edges of the pattern. I used to use window glass, transparency, sensitized board, foam, window glass with binder clips all the way around the edge. The window glass absorbs some UV, but not enough to matter if you do exposure testing.
The more of a point source UV lamp you use, the better, IME - also the more intense the better. I had great results with an unshielded mercury vapor lamp (most have a sheild to block the UV). It's best to actually do some exposure tests (which wastes a chunk of board, or resist film at least) to figure out what time is required at what distance from the light for best results.
I have no direct experience with method 4, direct toner transfer - I've read about it but not quite gotten to trying it. Basically you print a reverse pattern and then iron the toner off the paper and onto the board. There are various refinements of paper choice documented in various web-sites. I expect that pinholes may still be a problem, but you can presumably still touch them up with resist ink (or a red sharpie) before etching.
"Best" method 5 is a flat-bed plotter with a resist ink pen to draw resist ink directly onto the board, but finding one in working condition and drivers to print to it is quite a challenge these days, as they went out of fashion 20-odd years ago.
Method 6 is similar, but the toys are more common than flat-bed pen plotters in this decade, though not overly cheap - a small CNC machine, perhaps home-built, directly machines away the unwanted copper - no etching involved.
Well..I was thinking of just putting a halogen (on a dimmer) into tap water to make a hot bath for an etchant tray. It's have a nice danger level to make etching exciting :) That or get an aquarium heater.
Sounds like ferric chloride and ammonium persulfate don't react to titanium. D from BC
Compare the cost of a professional titanium-sheathed heater to that of an old microwave oven..
Best regards, Spehro Pefhany
--
"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
The method described on the following site works very well:
formatting link
Whatever method you choose, you will probably need to do a few before you get really good at it. Maybe start with real simple stuff, until you get the hang of it.
I think you've just described my "used once in a blue moon" homebrew setup! I get great results too from the (pretty crappy) laser printed positive photo transparencies. Sometimes I have to double them up to get a darker film.
I get very good results with a cheap HP DeskJet 5940 printer used with Mega Electronics Premium JetStar film. I use ferric chloride etchant in a small plastic container heated with very hot water in a larger container. Etching takes about 10 minutes with continuous agitation.
Well, since no one else mentioned it... You should also take care when laying out the traces.
Small, thin traces should not take sharp turns, etc... Or be so close together that etching time to clear them becomes an issue for other traces elsewhere on the board.
Personally, I'd use one of the cheap PCB fab houses. By the time you add up all your time and materials, you're probably paying more to DIY.
D from BC wrote in news: snipped-for-privacy@4ax.com:
I have a small food warming plate (from the surplus store, just bare glass with heating element tape applied) I used to heat a try to make small boards.
I used the toner trasnfer method , or manually masked boards, BTW.
"wale" skrev i en meddelelse news: snipped-for-privacy@b79g2000hse.googlegroups.com...
formatting link
- or whatever is closest to you!
Considering the hassle with corrosive chemicals, the volume occupied by equipment, the time wasted, the endless drilling of holes, the generally mediocre results and the inability to produce multilayer boards, the D.I.Y. methods is just not worth it I.M.O.!! With the prototype fab house you upload, pay and the PCB is in the mail 1-3 weeks later.
go to express pcb, download polygon software express pcb.. make rartowrk, have it fit 59 dolar special size if you can, palce order via internet, receive clean boars in 3 days.. holes vias great service. and great boards. this will let you get to the next stage of building stuff, and obsevin behavior, etc...
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.