Alan said:
Any suggestions on products for DIY PCBs?
Tried the Press-n-Peel transfer film, but it's crap. The film just
gets stuck in the fuser of the laser printer. Besides that, it's
expensive.
Drawing the layout on to the board with a Dalo pen or a Sharpie isn't
an option - it's way too complex.
Thanks.
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.
