Objective: proper toner transfer for 2 sided 1.5mm PCBs
- check if 1.5mm PCBs pass through the unmodded laminator: (NO)
- remove paper guides to prevent PCB from getting stuck (OK)
- check if proper refusing takes place after about 2-4 passes: (NO)
- measure temperatures: 170°C heater, 130°C drums (TOO LOW)
- hack the temperature pot: (NOPE)
- hack the NTC temperature sensor: (BINGO)
- check refusing after 4 passes: (NOT OK)
OK I hereby solemnly declare that toner transfer is officially CRAP for my equipment.
Printer: HP 2605DN, toner: original HP, transfer paper: pulsarprofx
So what did I do ?
First I disassembled the whole piece of sh.. again just to figure out I had to remove ALL of the works, just to get to the NTC temperature probe. While doing so I found out that the high voltage parts (T16C6 CN77 / CC 158U MAR 747. 2 thyristors I guess, couldn’t find the parts on google) are properly isolated from the rest of the circuits with 2 optocouplers (cosmo 3063). Then there are some opamps (LM358L) and comparators (LM393L). Last but not least, there’s even a microcontroller. No ATTiny, but it’s a HT46R47.
Anyhow, the NTC sensor stayed hidden under a big blob of black goop but at least I could measure some 85kΩ @ room temperature and about 20kΩ when hot (130°C on the drums). So I just added a 25kΩ pot to fake a lower temperature. Lo and behold, the laminator got hotter… Setting the pot to about 1.9kΩ pushed to fuser unit’s drums to about 170°C, accompanied by a lot of olfactory nastiness. Time to remember the correct spelling of the verb STINK !
Testing toner refusing on freshly scrubbed copper PCB after 4 passes (2 passes preheating, 2 with toner transfer paper) initially seemed to work, as this time the paper actually stuck to the PCB, but after removing the paper nothing was OK. 3/4 of the toner was washed away instantly, the rest stuck quite well but was smudged. The smudging looked like my experiments with a clothes iron and LOTS of heat. So I guess this time the laminator actually got too hot.
Conclusion: There seems to be no way of telling which make of toner and what kind of laminator do work and produce perfect results – except the stuff that is sold directly by the pulsaprofx people. I don’t want to flame too much here, but compared to traditional photographic transfer + NaOH development toner transfer ‘could have’ made making PCBs a lot easier, but looking at all the hassle and the bad results…
I’ve had enough of this !
What I’ll buy for Xmas:
- some plastic bowls for developing & etching
- PE bottles for the nasty chemicals
- NaOH pellets
- H2O2 + HCl for etching
- UV exposure stuff, maybe just a frame + lamp for starters
- Small drill press or small table top mill.
Using more chemicals might be environmentally questionable, but HCl/NaOH can be turned to NaCl + water if mixed properly to get a pH of 7.0 using e.g. indicator paper. But this step is also necessary when only etching toner transfered layouts. Comparing the amount of chemicals/energy that’ve been used to make this laminator (which I won’t be using anymore), I think it would’ve been wiser to stick with photographic transfer, which is known to work 100% once the best exposure time is found. I could’ve made dozens of PCBs and still stayed below the amount of waste that my ‘beloved’ laminator has become.
“What I’ll buy for Xmas”
Platinen will ich keine :-)
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