Quote:
Originally Posted by Terry_VK5TM
Look up 'photo resist film' on ebay etc.
Very cheap (although you have to wait for shipping) and you can make your own photo resist board in much the same manner as using the iron on technique.
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In the UK, negative photoresist dry film is actually quite cheap from UK suppliers.
EG: £4.59 post free for a 1 metre roll 30cms wide.
https://www.ebay.co.uk/itm/UK-1Roll-...UAAOSwY5pen-OU
It comes in a black light-proof wrapper and if kept in that wrapper it doesn't seem to degrade over time. I'm still using a roll that I bought in 2016 when I first started using this technique. I keep the roll in a desk drawer, unwrap it in subdued light (curtains drawn to keep out UV), cut off what I need and pop the roll back in the drawer.
I only buy genuine fibreglass FR4 laminate - not SRBP laminate, which is sometimes wrongly described on eBay as 'FR4'. The copper on SRBP has poor adherence to the substrate.glass-reinforced epoxy laminate material. FR-4 is the NEMA designation for composite material composed of woven fiberglass cloth with an epoxy resin binder that's flame resistant (self-extinguishing), which is why it's terms 'FR'.
https://en.wikipedia.org/wiki/FR-4
I clean the laminate with 0000 grade wire wool and wipe it dray with methylated spirt (known outside the UK as 'de-natured alcohol') and the film adheres really well.
There's no doubting that for occasional one-off PCBs the iron-on technique wins hands down. It obviates the need for a UV light box, creating a UV mask, applying the UV film, getting the correct exposure duration, the correct developer concentration, and all the associated costs. But if a UV light box is to hand, or if anyone wants to make a cheap UV exposure light, the negative resist film technique has much to commend it.
In the four years since I started using negative dry film, I guess I've successfully made more than fifty boards, (though none this year as my interests are developing elsewhere).
Whatever technique is used, at the design stage it will pay dividends to make the tracks as wide as they can be and the pads are large as they can be. Thin tracks will be undercut at the etching stage, and even if a PCB drill in a drill stand is used, small pads can easily be mis-drilled by the drill bit skidding or can tear off the pad. The more copper that can be left on the board, the shorter the etching time and the less the risk of undercutting. Many PCB CAD programs are intended for use in commercial PCB production and don't entirely lend themselves to DIY PCBs unless the tracks and pads are beefed up.
In all that I do, I aim to attain as good a DIY result as I can, but at the end of the day, even if a DIY PCB wouldn't win a beauty competition, if it's functional and we enjoy doing what we do, it's mission accomplished.
And yes, it makes no economic sense to go through all the rigmarole when we could send a Gerber file to a PCB house and get top quality commercially produced PCBs, but if we applied a cost/benefit analysis to any aspect of this or other hobbies, it wouldn't stand close examination. Except of course that we can't put a price of the enjoyment we derive. If it's not enjoyable, we wouldn't do it.
A couple of past forum threads on PCBs here might be of interest:
https://www.vintage-radio.net/forum/...//www.vintage-
https://www.vintage-radio.net/forum/...d.php?t=149574