Homebrew PCBs

Yup, that's thermal paper - it's the same technology used for printing
receipts at just about every point-of-sale system you'll ever come across.

The principle of the thing is the paper is pre-treated with carbon to
blacken when heated, so an image can be formed on it easily, and without
separate supplies.  The image fades with time.

Then why do people use this technology?  The printers are simple - cheap,
small, portable, fast, and reliable.  They never jam, they don't need any
kind of ink or toner, they don't need to be cleaned, they don't have a
"warm-up" time, and the people pulling orders at the warehouse don't have to
fiddle with clumsy higher-quality printers.

The only real drawbacks are
1) It doesn't scale up to big sizes well, which doesn't matter when you're
printing labels,
2) It doesn't do color or high resolution (or even grayscale), which doesn't
matter when you're printing shipping labels,
3) The images have bad shelf life, which doesn't matter when you're printing
shipping labels.

I think you'll have this problem with just about every vendor, as this seems
to be standard practice in my experience.  I know Digi-key and TI.com print
labels the same way.

With that, though, I'll confess - I've got quite a few bags of parts
labelled with their original thermal labels that I probably won't be able to
read next year.

-Andrew


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