12-06-2015, 04:49 PM
I bimble along as I have for decades now, making my own PCBs in my own way. I guess if I were starting out today, I'd give the 'iron on' laser print process a go as it cuts out a lot of the stages as compared to UV, but I'm in a rut as deep as a grave
I know that those further up the food chain than me (a lot further!), simply send a Gerber file to a PCB pool, and get a highly professional board for not much more than all the DIY faffing about, but I don't have the abiltiy or inclination to get into 'proper' PCB design. I don't use any PCB drafting programs - never got into them and I'm not keen on some aspects of the output I see - leastways, not for DIY etching and drilling. The tracks seem too thin and the pads needlessly small, so if I see a design I want to use, I tend to 'beef up' the tracks and pads in Phtoshop or Paint. I try to have the tracks and pads reasonably wide, to allow for any undercutting which can occur when exposing and etching a board.
Until late 2010 I had an aging HP printer which had a transparency setting and produced splendid solid print on acetates, but the printer died on me. I bought a well recommended Epson at the time, assuming it would produce as good if not better results on acetate, but I later found that no Epson printers support acetate printing. Maybe it's because OHPs have largely been superseded by Powerpoint presentations and digital projectors? Mostly, so long as it's not a complex PCB, I can get by if I tape two or three copies over each other. I don't use pre-sensitised boards - I spray my own, then if the process fails, I can just wipe the board clean with Meths and re-spray with UV lacquer.
Joe Freeman (formerly of this Parish), pointed me to a youtube video by a chap called 'Big Clive' who suggests how to alter the settings on Epson printers to get more solid print for PCB masks by changing the settings for saturation, density, contrast, colour and brightness to maximum, and to use the 'Epson Matte' paper setting. which I was hopeful about. I've tried that and it has produced a marginal improvement, but I've also tried a new type of film from Crafty Computer Papers for printing the artwork onto called 'micro porous film':
http://www.craftycomputerpaper.co.uk/.-M..._S048A.htm
Definitely better than normal OHP film on my Epson. The normal OHP film I've been using is much cheaper - presently £15.00 for 50 sheets:
http://www.amazon.co.uk/INKJET-CLEAR-PRI...B000KJO7BO
Big Clive's video about making photo resist PCBs with an Epson ink-jet is at the link below. He rambles on at length, but explians how to set the printer up at about the fourteen - 20 minute mark:
See: https://www.youtube.com/watch?v=W_oDBp_wgJQ.
I'm presently trying to produce a couple of PCBs for the 'mini mod' using the artwork kindly supplied by Ian Liston Smith, the mini-mod designer. Ian used a ground plane, which I don't think is really needed for something working at MW frequencies, but I've stuck to the design and have retained the ground -lane though I've tweaked the artwork, increasing the clearance from the tracks to the ground-plane, and have increased the size of the pads where it's possible to do so. I've had one attempt at etching the PCB, but it's not really to my liking, so I'll have another go. I've attached a pic of the exposed board, when etched. Not up to scratch and certainly way below professional standards. I try to aim for high skill, low tech and this effort doesn't meet the first criteria!
No sense to it of course, in terms of time and effort, when a commercially produced board - certainly a batch of boards, would probably cost less than the materials, but it's a hobby, isn't it?
As to UV exposure units, I made mine many years ago, but I'm very impressed with the one designed by Joe Farr at this link:
http://www.hobbyelectronics.net/con_uv-e...-unit.html
It uses 100 high brightness UV LEDs, which can be had for £3.00 post free at the link below. Yes, that's not a typo - 3 pence each!
http://www.ebay.co.uk/itm/100-pcs-3mm-2-...0011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D29271%26meid%3Dffa5459f77764cc487f81a75dc1086fb%26pid%3D100011%26rk%3D6%26rkt%3D10%26sd%3D270984675905&autorefresh=true
100 resistors for £1.00 and a piece of stripboard - total cost not much more than a tenner!
I’ve long since abandoned using ghastly ferric chloride as an etchant, both on cost grounds, and as it’s so messy. It’s only merit is that it lasts quite a long time in solution.
Instead, I use Sodium Persulphate clear PCB etchant. This is a much cleaner effective alternative to ferric chloride and has a 6 – 8 minute etch time at 45C – 50C. (above 50C it loses its strength). The bath life is a maximum of 4 – 6 weeks depending on use and operating temperature. Unlike ferric chloride, it leaves no residue – the solution turns pale blue in use. I warm it up with an aquarium heater and check with an infra-red thermometer, but you can stand the plastic etchant container in a washing up bowl of boiling water to warm up the etchant. You can use it cold – it just takes longer to work.
As the PCB etches, the liquid turns light blue and you can see through it to check etching progress, unlike Ferric Chloride. You can use it several times over. I use an aquarium heater to warm it up, and an aquarium air stone about 4” long, with a small aquarium air pump, placed in the bottom of a plastic cereal container to ‘bubble’ the solution to speed up the etching process, but you don’t have to.
I get Sodium Persulphate 1KG plastic bottles from a reputable hobby chemicals source, currently £13.99 a kG, which will make up to 5 Litres of etchant:
http://www.ebay.co.uk/itm/221237579788?_...2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
First pic below is of the mini mod PCB after exposure and developing. I've tweaked the original artwork of the ground-plane to give a bit more clearance around the tracks, and slightly increased the pad sizes. Second pic is the PCB etched, before it went in the bin - just not up to par. It evokes memories of schooldays - "tries hard, could do better". Quite so.
More another time.
I know that those further up the food chain than me (a lot further!), simply send a Gerber file to a PCB pool, and get a highly professional board for not much more than all the DIY faffing about, but I don't have the abiltiy or inclination to get into 'proper' PCB design. I don't use any PCB drafting programs - never got into them and I'm not keen on some aspects of the output I see - leastways, not for DIY etching and drilling. The tracks seem too thin and the pads needlessly small, so if I see a design I want to use, I tend to 'beef up' the tracks and pads in Phtoshop or Paint. I try to have the tracks and pads reasonably wide, to allow for any undercutting which can occur when exposing and etching a board.
Until late 2010 I had an aging HP printer which had a transparency setting and produced splendid solid print on acetates, but the printer died on me. I bought a well recommended Epson at the time, assuming it would produce as good if not better results on acetate, but I later found that no Epson printers support acetate printing. Maybe it's because OHPs have largely been superseded by Powerpoint presentations and digital projectors? Mostly, so long as it's not a complex PCB, I can get by if I tape two or three copies over each other. I don't use pre-sensitised boards - I spray my own, then if the process fails, I can just wipe the board clean with Meths and re-spray with UV lacquer.
Joe Freeman (formerly of this Parish), pointed me to a youtube video by a chap called 'Big Clive' who suggests how to alter the settings on Epson printers to get more solid print for PCB masks by changing the settings for saturation, density, contrast, colour and brightness to maximum, and to use the 'Epson Matte' paper setting. which I was hopeful about. I've tried that and it has produced a marginal improvement, but I've also tried a new type of film from Crafty Computer Papers for printing the artwork onto called 'micro porous film':
http://www.craftycomputerpaper.co.uk/.-M..._S048A.htm
Definitely better than normal OHP film on my Epson. The normal OHP film I've been using is much cheaper - presently £15.00 for 50 sheets:
http://www.amazon.co.uk/INKJET-CLEAR-PRI...B000KJO7BO
Big Clive's video about making photo resist PCBs with an Epson ink-jet is at the link below. He rambles on at length, but explians how to set the printer up at about the fourteen - 20 minute mark:
See: https://www.youtube.com/watch?v=W_oDBp_wgJQ.
I'm presently trying to produce a couple of PCBs for the 'mini mod' using the artwork kindly supplied by Ian Liston Smith, the mini-mod designer. Ian used a ground plane, which I don't think is really needed for something working at MW frequencies, but I've stuck to the design and have retained the ground -lane though I've tweaked the artwork, increasing the clearance from the tracks to the ground-plane, and have increased the size of the pads where it's possible to do so. I've had one attempt at etching the PCB, but it's not really to my liking, so I'll have another go. I've attached a pic of the exposed board, when etched. Not up to scratch and certainly way below professional standards. I try to aim for high skill, low tech and this effort doesn't meet the first criteria!
No sense to it of course, in terms of time and effort, when a commercially produced board - certainly a batch of boards, would probably cost less than the materials, but it's a hobby, isn't it?
As to UV exposure units, I made mine many years ago, but I'm very impressed with the one designed by Joe Farr at this link:
http://www.hobbyelectronics.net/con_uv-e...-unit.html
It uses 100 high brightness UV LEDs, which can be had for £3.00 post free at the link below. Yes, that's not a typo - 3 pence each!
http://www.ebay.co.uk/itm/100-pcs-3mm-2-...0011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D29271%26meid%3Dffa5459f77764cc487f81a75dc1086fb%26pid%3D100011%26rk%3D6%26rkt%3D10%26sd%3D270984675905&autorefresh=true
100 resistors for £1.00 and a piece of stripboard - total cost not much more than a tenner!
I’ve long since abandoned using ghastly ferric chloride as an etchant, both on cost grounds, and as it’s so messy. It’s only merit is that it lasts quite a long time in solution.
Instead, I use Sodium Persulphate clear PCB etchant. This is a much cleaner effective alternative to ferric chloride and has a 6 – 8 minute etch time at 45C – 50C. (above 50C it loses its strength). The bath life is a maximum of 4 – 6 weeks depending on use and operating temperature. Unlike ferric chloride, it leaves no residue – the solution turns pale blue in use. I warm it up with an aquarium heater and check with an infra-red thermometer, but you can stand the plastic etchant container in a washing up bowl of boiling water to warm up the etchant. You can use it cold – it just takes longer to work.
As the PCB etches, the liquid turns light blue and you can see through it to check etching progress, unlike Ferric Chloride. You can use it several times over. I use an aquarium heater to warm it up, and an aquarium air stone about 4” long, with a small aquarium air pump, placed in the bottom of a plastic cereal container to ‘bubble’ the solution to speed up the etching process, but you don’t have to.
I get Sodium Persulphate 1KG plastic bottles from a reputable hobby chemicals source, currently £13.99 a kG, which will make up to 5 Litres of etchant:
http://www.ebay.co.uk/itm/221237579788?_...2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
First pic below is of the mini mod PCB after exposure and developing. I've tweaked the original artwork of the ground-plane to give a bit more clearance around the tracks, and slightly increased the pad sizes. Second pic is the PCB etched, before it went in the bin - just not up to par. It evokes memories of schooldays - "tries hard, could do better". Quite so.
More another time.
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'
