DIY PCBs

Toner transfer using "ordinary" papers is possible.

Check out the Homebrew pcb group on yahoo groups.

Searching the archive will give lots of info, & there are useful files in the files & database sections.

-- Regards Malcolm Remove sharp objects to get a valid e-mail address

"Alan" wrote in message news: snipped-for-privacy@y10g2000prc.googlegroups.com...

For all prototyping, making smaall quantities etc. I do the following and get a very good finished board. You will need:

1) a laser printer (I use a cheap HP black & white), 2) a household clothes iron(non steamer) 3) some ordinary sheets overhead projector transparancies. 4) a good thick firm piece of heavy duty cardboard about 3mm thick (or a piece of MDF, chipborad etc.), make sure its good and flat , a little bigger that A4 size. This is used to press on when ironing, see below, refered to here as a Pressing Board. 5) Masking or 'sticky tape' 6) container with cold water big enough to be abl to place your artwork in, or preferably work near a cold ater tap. 7) Scissors8) Brasso, dishwashing liquid, one of those cleanig scourers (sort of a fibre stuff for wasing dishes) and some clean dry rags 8) A piece of A4 typing paper

Method: I never make boards larger tan A4 size so this methods works fine for me. I use Protel 99SE for the artwork. Use whatever S/W youhave. Make your artwork viewed from the component side of the board, and draw tracks on the bottom layer. Ensure that pad hole are turned on in the S/W, so that when you print your artwork (1:1 scale) the pad holes are visible. Print you artwork onto the transparancy using a laser printer. If you can fit more than one artwork onto a page do so, save reprinting and wasting transparancies, also handy when making more thaan one board. Cut a piece of PCB about 3mm bigger all around than required for your artwork. Using Brasso and a clean rag, vigourously clean your piece of PCB (copper side!). Only once it is 'mirror shiny' from the brasso polishing, wash the board both copper and fibre sides with the dishwashing liquid. Dry thoughouly with a clean dry cloth. Do not touh the cleaned copper side with your fingers. Cut a strip of masking or sticky tape abput 40mm long. Double it back on itself to form a loop, the stick side facing the outside of the loop. Place and stick this loop down in the middle of the Pressing board. Carefully set the PCB down on top of this sticky loop (copper side up). Using a clean rag or tissue toilet paper), press the PCB down firmly onto the Pressing board/sticky loop. The reason for the sticky loop is to prevent the PC from moving. Next cut your transparancy artwork out, leaving about a 50mm border from the outer edge tracks. Place the artwork down on top of the PCB (inked side of the printed artwork downwards so tht the laser ink and copper are against each other. Cut a few strips of sticky tape and stick down the transparancy so that it is firmly down onto the PCB, no ripples of bends, nice and flat. The transparancy being stuck down around its edges. Now the PCB and tranparancy should be firmly fixed to the Pressing Board, ready to apply the heated clothes iron. Place the A4 typing paper over the PC/transparancy - it shields the hot iron from direct contact with the transparancy, just in case the iron sticks to the transpancy due to some dirt that might be on the iron. You will now need to do a bit of experimenting with iron temperature, the downward ironing pressure you apply and time duration of ironing. I find that 180 deg. applied for about 3 minutes with 'mild' pressure using a slow progressive sliding motion works for me. You can lift one corner a bit to check if the ink has been transfered, if not continue a bit longer. If you apply too much pressure, you will find hat the tracks will begin to distort, spreading outwads as the ink melts and spreads under too much pressure. Once you are ready, remove the PCB/transparacy watch out its HOT!) from the Pressing Board and wasting no time place it under the tap with cold running water. When cool peel the transparacy off using a firm steady rolling motion (don't rip it off). Check all the tracks, if all isOK then well done. If you find some pieces did not make, you can fill the missing pieces in with a Dalo or other cheaper type of water resistant pen. Worst case, you will have to clean the PCB again, removng all the laser ink with Brasso and starting again. Before you drill the pad holes and solder, clean all the laser ink off with Brasso and wash with dishwashing liquid, then dry.

Hope this description is of help to you - it takes a bit of practice to perfect, but is a cost effective way of producing a decent looking board.

This will, with experience, work well. I have done it many times. Don't use economode on the laser.

"APR" >> gets stuck in the fuser of the laser printer. Besides that, it's

In my experience the laser makes a lot of difference. I got good results when I could use a Laserjet 5000. Using a Laserjet 4Si never gave good results as it does not put enough toner on the transparancy. I tried a lot of different tranparancies and papers but to no succes. What type of Laser do you use?

petrus bitbyter

I've used a number of different transparancies, currently using Apollo. The part number is PP100C-20-A4A Non-Striped in a pack of 20 sheets - bought it at Officeworks. The Laser is a cheap HP LaserJet 1020 also purchased at Officeworks about two years ago, and still running on the original cartridge. Yes, thats right, don't use the economode, the more toner on the transparancy the better!!

See my response to your post in sci.electronics.design. To summarise: Feed your sheet from the manual bypass input, & flip down the exit tray, so that the sheet never has to go around corners. That'll keep it from jamming.

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    W
  . | ,. w ,   "Some people are alive only because
   \\|/  \\|/     it is illegal to kill them."    Perna condita delenda est
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180c is exactly the right temperature to melt laser/photocopier toner.

Once you've etched, acetone/turps should remove the toner from your PCB.

--
    W
  . | ,. w ,   "Some people are alive only because
   \\|/  \\|/     it is illegal to kill them."    Perna condita delenda est
---^----^---------------------------------------------------------------

You can tweak most lasers to up the toner density. First, look for the green dial under the lid of the laser printer. After that, twiddle the driver settings under Windows. If you're still getting poor coverage, change the cartridge for a new one.

--
    W
  . | ,. w ,   "Some people are alive only because
   \\|/  \\|/     it is illegal to kill them."    Perna condita delenda est
---^----^---------------------------------------------------------------