11-05-2016, 08:21 AM
Thanks for reading the thread guys, and for your comments.
Re the undrilled hole Joe, that was well spotted! I'd have discovered it when I tinned the board, as I always do, but I guess an error rate of less than 1% isn't too bad for an old buffer!
Producing opaque masks does present a bit of a challenge and I don’t think any laser printer, whether for commercial or domestic use, or any type of laser film produces a 100% opaque mask, which is why some hobbyists seem to use 90gsm tracing paper rather than acetate film, and others go for the ‘iron on’ technique. But as you Grant says, you can get away with taping two or sometimes three images together. For many years before home printers became the norm, I used to get acetates done at copy shops and tape them together. Then I had an HP inkjet printer which had an acetate setting and made first class masks. When that gave up the ghost I replaced in with an Epson, assuming that it would print onto acetate, but like others, I discovered that no Epson printers will print onto acetate, which is where ‘Big Clive’ came on the scene and he discovered how to fool the printer. Using his tips in his youtube video, I’ve have rigged the settings on my Epson printer to print properly onto acetate, and the images are totally opaque when printed onto 'micro porous film'. When printed in reverse so that the ink side can be placed next to the board, the etched PCBs when viewed through a microscope have much cleaner edges.
The developer sold by Mega is simply sodium metasilicate pentahydrate. They sell a 500g plastic bottle of crystals for £11.90, which is double the price that sodium metasilicate pentahydrate can be bought for:
http://www.ebay.co.uk/itm/1kg-Sodium-met...20c0693084
1KG £12.99 post free
The instructions on the Mega bottle are far too broad. They say ‘500g makes 10 – 20 Litres’, so that’s 50g to 1 – 2 Litres. I find that if I use only 1 Litre it’s much too concentrated and risks stripping the board completely, so I start with it weak and add crystals till it becomes effective. I find it lasts for about three months. If you're reading this Grant, I'd be interested to know what proportions of water:developer you use.
As to etchant, as I've mentioned before, I find sodium persulphate is a much cleaner alternative to ferric chloride, and I’m surprised that so many on internet videos soldier on with ferric chloride. Sodium persulphate just turns light blue in use, and can be re-used. The only snag is that it’s more effective at 40 – 45 degrees C. That’s fine when first mixed as you can use hot water, but if stored for re-use it needs heating up, for which I use an aquarium heater, though they’re thermostatic and shut off at about 30C. When I get round to it I’ll dismantle the heater and bridge the bimetal strip. The etchant still works if not heated – just takes a bit longer.
http://www.ebay.co.uk/itm/1kg-Sodium-Per...Sw9N1Vm8bZ
£13.99 post free for 1 kG
Primarily, I started the thread to mention the UV film technique, which is new to me and obviates both pre-sensitised or self-sprayed UV lacquer, so seems quite promising, but I'll reserve judgement on that.
The other thing is the UV light-box for about £20 by 're-purposing' a Maplin two tube fly killer. Exactly on the right UV spectrum for PCBs, more powerful than the little Mega box which is an unbelievable £149.
As you say Gary, unless you're going to make lots of PCBs, it's a non-runner, but the laser printer/iron on technique is a zero cost option as you just use glossy paper torn from magazines as a print medium, so for anyone who has a laser printer, that cuts out a lot of faff. I got into making PCBs with UV back in the early 80s as most of what I've done over the years has been home-brew projects such as simple test gear, receivers, and gadgets, which I still do. I don't find making PCBs for my projects a chore, or I wouldn't do it! The only commodity that's scarce is time, which I seem to have less and less of, and as the years pass, I become only too aware that I'm approaching my appointed time with the grim reaper, as we all are, but not for some time yet I hope.
Meanwhile, I'll carry on enjoying life, as indeed I do!
Re the undrilled hole Joe, that was well spotted! I'd have discovered it when I tinned the board, as I always do, but I guess an error rate of less than 1% isn't too bad for an old buffer!
Producing opaque masks does present a bit of a challenge and I don’t think any laser printer, whether for commercial or domestic use, or any type of laser film produces a 100% opaque mask, which is why some hobbyists seem to use 90gsm tracing paper rather than acetate film, and others go for the ‘iron on’ technique. But as you Grant says, you can get away with taping two or sometimes three images together. For many years before home printers became the norm, I used to get acetates done at copy shops and tape them together. Then I had an HP inkjet printer which had an acetate setting and made first class masks. When that gave up the ghost I replaced in with an Epson, assuming that it would print onto acetate, but like others, I discovered that no Epson printers will print onto acetate, which is where ‘Big Clive’ came on the scene and he discovered how to fool the printer. Using his tips in his youtube video, I’ve have rigged the settings on my Epson printer to print properly onto acetate, and the images are totally opaque when printed onto 'micro porous film'. When printed in reverse so that the ink side can be placed next to the board, the etched PCBs when viewed through a microscope have much cleaner edges.
The developer sold by Mega is simply sodium metasilicate pentahydrate. They sell a 500g plastic bottle of crystals for £11.90, which is double the price that sodium metasilicate pentahydrate can be bought for:
http://www.ebay.co.uk/itm/1kg-Sodium-met...20c0693084
1KG £12.99 post free
The instructions on the Mega bottle are far too broad. They say ‘500g makes 10 – 20 Litres’, so that’s 50g to 1 – 2 Litres. I find that if I use only 1 Litre it’s much too concentrated and risks stripping the board completely, so I start with it weak and add crystals till it becomes effective. I find it lasts for about three months. If you're reading this Grant, I'd be interested to know what proportions of water:developer you use.
As to etchant, as I've mentioned before, I find sodium persulphate is a much cleaner alternative to ferric chloride, and I’m surprised that so many on internet videos soldier on with ferric chloride. Sodium persulphate just turns light blue in use, and can be re-used. The only snag is that it’s more effective at 40 – 45 degrees C. That’s fine when first mixed as you can use hot water, but if stored for re-use it needs heating up, for which I use an aquarium heater, though they’re thermostatic and shut off at about 30C. When I get round to it I’ll dismantle the heater and bridge the bimetal strip. The etchant still works if not heated – just takes a bit longer.
http://www.ebay.co.uk/itm/1kg-Sodium-Per...Sw9N1Vm8bZ
£13.99 post free for 1 kG
Primarily, I started the thread to mention the UV film technique, which is new to me and obviates both pre-sensitised or self-sprayed UV lacquer, so seems quite promising, but I'll reserve judgement on that.
The other thing is the UV light-box for about £20 by 're-purposing' a Maplin two tube fly killer. Exactly on the right UV spectrum for PCBs, more powerful than the little Mega box which is an unbelievable £149.
As you say Gary, unless you're going to make lots of PCBs, it's a non-runner, but the laser printer/iron on technique is a zero cost option as you just use glossy paper torn from magazines as a print medium, so for anyone who has a laser printer, that cuts out a lot of faff. I got into making PCBs with UV back in the early 80s as most of what I've done over the years has been home-brew projects such as simple test gear, receivers, and gadgets, which I still do. I don't find making PCBs for my projects a chore, or I wouldn't do it! The only commodity that's scarce is time, which I seem to have less and less of, and as the years pass, I become only too aware that I'm approaching my appointed time with the grim reaper, as we all are, but not for some time yet I hope.
Meanwhile, I'll carry on enjoying life, as indeed I do!
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
