Electronic – What type of silkscreen ink is used in PCB manufacturing

Well I've made 1 million units for a product and they all had silkscreen and we fought over the cost of a resistor so it's not that cost prohibitive. Yeah I guess there is a cost associated with that but it's not that much. Also when you need to do rework, or when at the end of the line they are repairing boards that didn't pass testing, you want to be able to say "yeah replace U1 and change R17 to 33 Ohms" without having to haul out the schematic and the layout. Sure some factories will have computers with your drawings out there, and some have dirt floors ;)

For 402 components or vias just move your silkscreen, I mean I have 201 components that are labeled properly it's a matter of taking the time to do it.

So in short I agree with you I always prefer silkscreen, the only time I don't do it is when I'm making something for a hobby for myself and I'm being really cheap. Even then I usually try to label the parts in copper. Not saying you should do that for a real board though.

What you can do with an ink printer is to produce a mask by printing onto a transparent (ink compatible) sheet. This is then used to control the exposure of photo sensitized board under a UV light.

Laser toner works as a transfer method because the 'ink' is actually a thermo-plastic (i.e. not 'ink' as in the inkjet) that can be re-heated with an iron and made to stick onto the copper surface as a resist.