I believe a new thread should be started on how to BREW PCB PROTOTYPE IN A FLASH
Some of the more experience contributors to this fora probably has a wealth of information on this
and the safety use of chemicals especially where beginners are concerned.
I have been using toner transfer method for over twelve & half years for even small scale production runs.
CAUTION: FERRIC CHLORIDE MUST BE HANDLED WITH CARE. THIS IS A MESSY CHEMISTRY.
1. If you will be prototyping most of all your projects then it's a good investment
to get yourself an A4 size Laminator that can handle media thickness of about 400 - 600 microns.
Laminators with Four rollers is OK, eg Swordfish 240HD with the Temperature nob at maximum setting.
Optionally you can modify the circuit with one or two resistors to increase the roller temp. to around
200C - 270C.
2. For just one time PCB prototyping a Pressing Iron with settings to Linens will do the job.
But remember repeatability for PCB track widths of less than 0.4mm can be problematic with
pressing irons. Pressing too firmly in order to transfer toner to PCB might spread SMD pads
& tracks to bridge.
3. Laser printers with toners made from pulverized plastic is the key.
Thanks to HP marketing strategy, these days HP is selling its laser printers almost for the
price of a toner cartridge.
The old HP laser printers are the best, these deliver darker/dense toners onto the printing media.
My preference is for the HP Laserjet 3 till this broke down, but am currently using
HP Laserjet 1022 for PCB toner transfers.
4. This is the key. Paper to print your PCB circuit layout on.
If you live in Africa, get yourself the DStv GUIDE magazine, this is a low cost
colour semi glossy paper of about 40 microns thick.
In the UK get the Toolstation catalog or ARGOS catalog. Maplin catalog might work, not tried it.
One clue is that, when these magazine are sufficiently wet, rubbing it between your thumb & forefinger
the paper easily breaks up under running water.
for building your prototype PCB step by step.
The website above make reference to PulsarProFX. Here is my personal experience with their toner transfer
A pack of 10 sheets cost $14.95
20.3cm x 457.2cm toner sealing film cost $8.95
All above cost exclude shipping. Upsides of PulsarProFX Toner Transfer paper:
1. Paper thickness of about 220 microns makes it dimensionally stable.
More of a light card than paper.
2. The dextrin coating on the card promotes an excellent toner release when socked in water.
It releases the toner like magic.
Besides you don't have to rub off the paper with a brush or your fingers to loosen the paper.
3. The toner transfer paper can be used for the second time.
As soon as the toner is released, place the transfer paper on a flat surface.
Do not heat to dry, as this may curl the paper.
Once the dextrin coating is touch dry, place the paper in between two PCB's to straighting out any creases.
4. Toner sealing film gives a nice shiny green colour over the black toner given an impression of a
solder resist coating. Downsides of PulsarProFX Toner Transfer paper:
1. It's difficult for the toner to adhear in a dense manner as you would expect from other printing media.
Remember under printer properties, Print Density is set to max.
EconoMode is off. Resolution at 600 or 1200dpi.
2. With paper thickness of about 220 microns you will have to select a higher toner fuser temperature setting.
You do this under 'Paper Options'. Bond, Archive or Cardstock gives a higher fuser temperature,
whiles light< 75g/m2 and Transparency gives a lower fuser temperature comparatively.
With Lower temperatures the fuser is unable to cause the toner to bind to the dextrin coating.
3. Paper thickness of 220 microns makes toner transfer to PCB not an exact science, even with a modified
laminator with temperature setting at 270C, and running the PCB a couple of times through the laminator.
4. Applying the GreenTRF toner sealing film on toner areas with micro pores does not cover these micro gaps well.
My impressions of the GreenTRF is for aesthetics I must say.
I have been using toner transfer for PCB prototyping and small scale productions runs with 100% repeatability
over the past twelve years. It works so well.
For prototypes I never bother to remove the toner over the copper tracks, but for the SMD pads I do it with
a blunt 0.8mm drill bit on a flexible drive shaft with motor running.
I must be possibly doing something wrong for the toner transfer paper from PulsarProFX not to work 100%
all of the time.
Developing code for Microchip microcontrollers and not able to field test ones application on a PCB must be
a challenging one.
It's worth while to invest in desktop PCB fabrication tools, it's entirely possible to do this on your own.
I stand to be corrected.
post edited by Hanspeter - 2008/11/05 07:26:31