Homebrew PCBs

There seems to be a lively discussion about the use of laminators, so
I think I should chime-in. I bought a cheap 9" pocket laminator from a
Wal-Mart, then ripped out all the temperature control wiring. I then
wired-in a cheap process controller (such as can be found on Ebay for
~$35), using some type-T thermocouple wire. This lets me precisely set
the laminator temperature. The process controller had an internal
relay capable of switching 2 amps, which happily was also the load
which the heating element presented.

The laminator provides superior uniformity, compared to a clothes
iron. With an HP toner cartridge, Staples "Photo Basic Glossy" paper,
and the temperature set to 145 degC, I get utterly repeatable results.
The transferred toner is durable enough to withstand vigorous
scrubbing with a soft toothbrush. 15 mil lines and pads are clearly
defined, making a TQFP package usable for the first time in MY experience.

As I said, the laminator helps mostly with uniformity, but the paper
is the other part of my process which really makes it successful.

Presumably an old laser printer fuser assembly can be modified in a
similar way. Keep in mind that most of the available process
controllers seem to accommodate many different types of thermocouple
junctions, so you don't have to be choosy about what type you need.

Marshall

That is certainly the case with modern programmable ones, but older
surplus controllers will often only work with one type of thermocouple
and some only with certain thermistors, so take care there. Old
surplus stuff can be a lot cheaper, but one needs to watch out for
that.

For fusers/laminators a thermistor control seems to be perfectly fine
anyway, and that can be done with quite a simple homebrew circuit if
one doesn't like spending the money.

ST

On Jan 16, 2008 10:28 PM, josemj1 <kerwoodderby@...> wrote:
> Keep in mind that most of the available process
> controllers seem to accommodate many different types of thermocouple
> junctions, so you don't have to be choosy about what type you need.
>
> Marshall
>