Homebrew PCBs

On Thu, 08 Jun 2006 04:20:22 +0200, Herbert E. Plett <cachureos@...>  
wrote:




At least those last three statements are IMO wrong speculation.


> -the 'curing' process applies heat until the 'residue' burns (carbonizes)
> leaving something stuck on the surface that is not water (etchant)  
> soluble.

The curing temperature is maybe 200 or 300C (wild guess). I don't think  
anything carbonizes.
My best guess is it just dried all the water out. Water soluble ink may be  
waterproof when fully dry.
Air drying for two days did not have the same effect though, maybe due to  
water in the air.

> -dark inks need very little residue to be visible, whereas light inks  
> (yellow)
> need a thicker residue to be visible, so after 'curing' more stuff is  
> available
> to protect the surface. This explains why black has proven useless and  
> yellow
> the best.

This is one hypothesis, at best, it explains nothing unless you have  
proven it. I don't believe more yellow ink is used.

> -alternate reason may be that black is already carbon and does not  
> change by
> heating while yellow is some sort of delicate organic pigment that nicely
> 'burns' and sticks during curing. Remember that those who report success  
> say
> the yellow has to turn brown to work.

Slightly brown, not burnt! It is in no way proven that the turning brown  
has anything to do with it, i just use it to tell me "ok that's surely  
enough" lacking any temperature control for now.

Quite frankly, most of your post didn't seem to apply very much. IMO it is  
probably the resin or binder, not the pigments, doing the resisting.

ST