Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Short version: With a little rewiring, this 150C $20 laminator
∗ looks like it will be good for ~115C lamination of
∗ Riston negative photoresist film onto copper-clad
∗ boards. It has spring-loaded silicone rubber
∗ rollers and with another simple mod, works OK with
∗ 1.6mm FR4 material.


Yesterday I found this illustrated article:

∗ http://ultrakeet.com.au/index.php?id=article&name=superFuserV2

depicting a seriously inexpensive Lowell L00L280 laminator:

∗
http://www.officeworks.com.au/retail/products/Office-Supplies/Presentation/Laminating-Machines/Pouch-Laminating/LOOL280


for AUD$19.47 from Officeworks in Australia. I guess identical
laminators are available in other countries, perhaps by different names.

The article shows how to modify the laminator to make it hotter, for the
purpose of making PCBs with toner transfer.

Here I discuss my plan (implemented as I wrote it) to make it run cooler
for the purpose of laminating Riston or similar negative photoresist
onto FR4 board. I will only be able to test it in a few weeks time when
I get some A5 sheets of Riston MM540 film from:

∗ http://www.ebay.com/sch/gaminn/m.html

The laminator moves the material very slowly - about 4mm a second.

There's a strip of galvanized steel at the exit side which needs to be
removed in order that the 1.6mm material board won't hit it. The two
rollers are spring-loaded and the laminator is perfectly happy with
1.6mm PCB material going through it.

The rollers primarily spring apart, though they may also bend a little.
Both rollers seem to be some kind of high-temperature silicone rubber
with a presumably steel core.

The rollers are not directly heated, but are largely surrounded by two
aluminium extrusions which contain heating elements. I wouldn't rely on
the rollers themselves to fully heat the FR4 material, so I plan to
preheat the FR4 to 80C, 100C or whatever before putting it through the
laminator.

Riston MM540 lamination involves temperatures of 105C to 120C, with 115C
recommended:

∗
http://www2.dupont.com/Imaging_Materials/en_US/assets/downloads/datasheets/mm500series.pdf


I don't have an easy way of testing the temperature of this laminator,
but I think it is too hot.

There are two thermostats. The heating elements are in series and are
driven by diodes so the positive half of the mains cycle goes to the
heater when the right thermostat (red and yellow wires, 150C) is on and
the negative half goes to the heater when the left thermostat (black and
yellow wires, 125C) is on. So the heater runs at full power to warm the
extrusions up to 125C, and then runs intermittently at half power to
maintain a temperature of about 150C. When the right (150C) thermostat
turns off, the orange READY LED goes on.

So I think this is a 150C laminator. The ultrakeet team install a 160C
thermostat in place of the ∗left∗ (160C) thermostat. This is the right
on on their photos. So I think they are cranking the temperature only
marginally to 160C, with the READY LED going on once it reaches 150C.

I could replace both thermostats, or not bother with the fast warm-up
one and concentrate only on the right thermostat. For now, I have
pulled off the black wire (left thermostat, 125C) and the red wire
(right thermostat, 150C) which also drives the READY LED. I put the red
wire where the black one was (on the left thermostat, 125C) and now the
machine should run at about 125C, with a longer warm-up time, and with
the READY LED turning on once this 125C thermostat turns off.

Previously, a drop of water would boil away in a few seconds, with lots
of noise, on the top extrusion. Now, the drop sits there for a moment,
starts bubbling and takes 30 seconds to boil away gently.

I don't have a thermometer, but I reckon this is in the range of
temperatures suitable for Riston.

I imagine that the actual temperature of the lamination process could be
fine-tuned by what temperature the board was preheated to.

I haven't reassembled the laminator, but I think the plastic case will
not present any obstacles to passing 1.6mm FR4 material.

- Robin Melbourne, Australia

http://www.firstpr.com.au/rwi/dfish/