Homebrew PCBs

----- Original Message ----- 
From: "derekhawkins" <derekhawkins@...>
> The prevailing view seems to be that since industry uses photoetching
> then it's far too expensive and too involved for the home. Either that
> or "we must do things differently" prevails. Normally, I don't get
> involved in these TT debates but the insinuation by a poster that one
> needs a $500.00 exposure box for photoetching was too much to resist.

That's a little too far over the top. From a complexity and startup cost 
point of view, the choice is rather simple:

** cost of a UV box, versus cost of a laminator;
** cost of sensitized pre-clad or laminant, versus cost of transfer paper;
** cost and dimensional stability of mylar or acetate, versus short-term 
stability of card stock backed transfer paper.
** cost of developer, versus cost of plain water to remove transfer paper;
** reusability of acetate or mylar, versus one-shot nature of transfer 
paper;
** inkjet or plotter on hand, versus laserjet on hand.

For production runs of many multiples on automated equipment, photo exposure 
has some advantages. For production runs of one or very few, the case for 
100% of "HOMEBREW PCBs", you'll have to explain as though to a young child 
the advantages that offset the cost and complexity of photo exposure.