Making circuit boards
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George Sephton
Senior Member
Depends on what you have, do you have a UV light and the deveoper, if not then iron on. They both work equally well but there's more "skill" in ironing on, ie it may not work and after a bit of practice you see what needs to be done and how long the iron has to stay on the paper for. For iron on remember it's toner onto photo paper, ink rubs right off.
Both methods can yield excellent results if done right. But both need some amount of practice for that. One disadvantage of toner transfer is that it's difficult to make just a small board - meaning you'll end up wasting the rest of the letter-sized transfer paper, which makes it a bit expensive. On the other hand, photo-resist board material is more expensive by itself and needs more care with handling (no exposure to light). No matter which method you chose, I'd suggest doing a few trial boards as an exercise before you launch into anything complex.
Don'f forget there will be some significant startup expenses - exposure box (for photo-resist) or transfer paper (for toner transfer), raw copper-clad board material, etching tank, etching solution, brushes etc. (to clean the boards before and after etching), drill stand and drills. To get decent results you'll need decent quality equipment, and that does not come for free. In addition, those etching chemicals need to be replaced after a few uses and are highly toxic (and also stain your clothes), so don't do it ANYWHERE near food, assure good ventilation, use rubber gloves and protective goggles etc., thoroughly wash your hands after etching. And by all means keep the equipment away from children. And don't spill it into the sink, instead bring it to a recycling station.
If you only need to do a few boards overall, you may want to look into having them made professionally. No nasty chemicals, no time spent on drilling dozens or hundreds of holes, no wasted boards etc. I did a few boards myself (toner transfer) but in the end decided it wasn't worth the time and effort compared to just ordering them from a low-cost vendor. ExpressPCB offers 3 boards for around US$60 including shipping (but you need to use their design software). PCBCart accepts standard Gerber files and is cheaper for larger quantities and more advanced options (silkscreening, multi-layer boards, Gold plating instead of solder reflow). The cheapest for hobby boards I've found so far is www.platinenbelichter.de (they also ship internationally for very reasonable cost, just ask), their capabilities are similar to a hobbyist (meaning, no special plating, no silkscreens, no through-plated vias) - etched and drilled boards, for a very low price, and you can just send them a picture (e.g. PDF) of your board layout instead of Gerbers.
Don'f forget there will be some significant startup expenses - exposure box (for photo-resist) or transfer paper (for toner transfer), raw copper-clad board material, etching tank, etching solution, brushes etc. (to clean the boards before and after etching), drill stand and drills. To get decent results you'll need decent quality equipment, and that does not come for free. In addition, those etching chemicals need to be replaced after a few uses and are highly toxic (and also stain your clothes), so don't do it ANYWHERE near food, assure good ventilation, use rubber gloves and protective goggles etc., thoroughly wash your hands after etching. And by all means keep the equipment away from children. And don't spill it into the sink, instead bring it to a recycling station.
If you only need to do a few boards overall, you may want to look into having them made professionally. No nasty chemicals, no time spent on drilling dozens or hundreds of holes, no wasted boards etc. I did a few boards myself (toner transfer) but in the end decided it wasn't worth the time and effort compared to just ordering them from a low-cost vendor. ExpressPCB offers 3 boards for around US$60 including shipping (but you need to use their design software). PCBCart accepts standard Gerber files and is cheaper for larger quantities and more advanced options (silkscreening, multi-layer boards, Gold plating instead of solder reflow). The cheapest for hobby boards I've found so far is www.platinenbelichter.de (they also ship internationally for very reasonable cost, just ask), their capabilities are similar to a hobbyist (meaning, no special plating, no silkscreens, no through-plated vias) - etched and drilled boards, for a very low price, and you can just send them a picture (e.g. PDF) of your board layout instead of Gerbers.
George Sephton
Senior Member
if you want an investment by a bubble tank too, it speeds it up easier, and its better than stirring it yourself.
SilentScreamer
Senior Member
I've made several photo resist boards in daylight. So long as it isn't exposed to sunlight for too long its fine.
I work with pre-sensitised boards in subdued daylight in a room, I just turn off the fluorescent lights because they apparently contain some UV radiation. Photo resist is sensitive to UV light at a certain frequency, not the intensity of that UV light so much. So "normal" lighting should be OK. I use a UV bulb from GE, looks like the normal Mercury Vapour bulbs, in a outside flood light holder. The extra glass seems to rob some of the UV and I therefore expose my boards for 12 - 14 minutes (through a second glass). Works well for me.
George Sephton
Senior Member
You can tell when it's been exposed, especially after your first time, as it goes from greeny brown to brown. its a pretty distinct colour change.
I go the lazy route and order from a prototyping place, but I've been looking at the 'Fab-in-a-box' for a while, now. Might not fit your needs, but I thought I'd pass it on.
Ive never tried the toner method, but had consistent good results with UV. I never worry about the ambient light as the board is only exposed for a few seconds between exposure, developing and etching.
If you make your own light box and etching tank, then costs can be reduced, but as Womai pointed out, the photo-resist board is more expensive.
If you make your own light box and etching tank, then costs can be reduced, but as Womai pointed out, the photo-resist board is more expensive.
Mycroft2152
Senior Member
The "Fab-in-a-box" is a nothing special, just a good summary of the Toner Transfer process using their expensive products. Convenient--yes, revolutionary--no.I go the lazy route and order from a prototyping place, but I've been looking at the 'Fab-in-a-box' for a while, now. Might not fit your needs, but I thought I'd pass it on.
Overall, you can get much finer pcbs using the photo method over the TT method.
For those real die-hards, there is the also the "direct to pcb printing" using and inkjet printer and pigment ink, or the "Toner dusotng" method using an inkjet printer and toner.
All of these techniques have a learning curve, don't be surprised if you have to trash the first few boards.
Myc
Making PCB Boards
Hi.
I tried the Toner transfer system without much luck - I could never get the tonor to transfer :>
So I tried using the Kinsten Phositve Resist boards. I was very happy with the result. I made a small exposure box using a Black Light Compact Fluroesent globe.
This was basically a foil lined box about 7" x 5" x 5" One side had a normal bulb socket and the lid was glass. I could lift the glass up and swap the bulb for a white one if I wanted a light box to match double sides films together.
I printed the PCB layout onto clear film (Overhead Transparencies) , and then exposed it to the bulb for 5 mins. Dropped it into the developer and washing gently and I had a perfect board.
After etching with Ferrous Chloride I could see very small details like the 'pin 1' on the IC sockets.
All up the cost of the light box came to about $30
This company had all the boards and developers I needed - Boards from $3.00 and Developer from $2.75
http://www.kalex.net.au/products/printed-circuit-board
And I got the FeCl from Disk Smith for $12.95
If you have some Acetone - I found it is perfect for cleaning toner off clear film so you can reuse it later.
Hope this helps someone
Dave
Hi.
I tried the Toner transfer system without much luck - I could never get the tonor to transfer :>
So I tried using the Kinsten Phositve Resist boards. I was very happy with the result. I made a small exposure box using a Black Light Compact Fluroesent globe.
This was basically a foil lined box about 7" x 5" x 5" One side had a normal bulb socket and the lid was glass. I could lift the glass up and swap the bulb for a white one if I wanted a light box to match double sides films together.
I printed the PCB layout onto clear film (Overhead Transparencies) , and then exposed it to the bulb for 5 mins. Dropped it into the developer and washing gently and I had a perfect board.
After etching with Ferrous Chloride I could see very small details like the 'pin 1' on the IC sockets.
All up the cost of the light box came to about $30
This company had all the boards and developers I needed - Boards from $3.00 and Developer from $2.75
http://www.kalex.net.au/products/printed-circuit-board
And I got the FeCl from Disk Smith for $12.95
If you have some Acetone - I found it is perfect for cleaning toner off clear film so you can reuse it later.
Hope this helps someone
Dave
demonicpicaxeguy
Senior Member
i've also tried the toner transfer method a few times but at the end of the day it's really limited to traces down to 1 mm and that pushing it at the best of times,
the photo resist method so far i've found to be very good, and you don't actaully need a darkroom either, i just use my storage room with the light off and the door slightly ajar so i can see what i'm doing
my prcoess is this:
1, print artwork onto normal inkjet paper no you don't have to goto the expense of tracing paper or transparency paper, also a note here if for trace sizes down to 0.30mm inkjet paper will work ok, however if you want to venture into the tqfp sizes .20mm and below you will need a laser printer
*make sure artwork is flipped before printing
2, secure printout on somthing like perspex or a glass sheet with the ink facing up
3, secure pre coated pcb with resist facing down onto inside of paper
4, using an energy saver or tubular flourescent from between 1 to 1/2foot away from pcb expose to light for at least 10 to 15 mins not if your light source is too close you will get slight blurring when pcb is developed
5, personally i use 1 tabe spoon or draino to 500mm of COLD tap water but if you really want to you can use the developer,and agitate the board in the water and i don't mean sit it in to draino and move the liquid around it, hold the board with long nose pliers and move it around with a little haste
*ok yes if you want boards really quickly and you are really impatient by all means heat the water however it will yes remove the large areas of resist quickly however i did notice that those smaller lines between thin traces can also eat into the traces and somtimes break them as well even before the larger areas have finished
6,etching the copper, i use ferric chloride, if your doing a pcb with traces 0.4mm and bigger by all means heat it to speed things up then wash it off with water,,,,,
however if you're doing pcb's with traces 0.40mm and smaller i've found actaully not heating it and using it straight out of the bottle at room temp is actaully better.... it still seems to chew away at those large areas as quickly is if heated but it won't destroy those finer traces and etch away under the photo resist layer that make those up as quickly
also bear in mind that increasing the size of some of your traces is somtimes also nessessary depending on how well the ink from you inkjet blocks the light
the photo resist method so far i've found to be very good, and you don't actaully need a darkroom either, i just use my storage room with the light off and the door slightly ajar so i can see what i'm doing
my prcoess is this:
1, print artwork onto normal inkjet paper no you don't have to goto the expense of tracing paper or transparency paper, also a note here if for trace sizes down to 0.30mm inkjet paper will work ok, however if you want to venture into the tqfp sizes .20mm and below you will need a laser printer
*make sure artwork is flipped before printing
2, secure printout on somthing like perspex or a glass sheet with the ink facing up
3, secure pre coated pcb with resist facing down onto inside of paper
4, using an energy saver or tubular flourescent from between 1 to 1/2foot away from pcb expose to light for at least 10 to 15 mins not if your light source is too close you will get slight blurring when pcb is developed
5, personally i use 1 tabe spoon or draino to 500mm of COLD tap water but if you really want to you can use the developer,and agitate the board in the water and i don't mean sit it in to draino and move the liquid around it, hold the board with long nose pliers and move it around with a little haste
*ok yes if you want boards really quickly and you are really impatient by all means heat the water however it will yes remove the large areas of resist quickly however i did notice that those smaller lines between thin traces can also eat into the traces and somtimes break them as well even before the larger areas have finished
6,etching the copper, i use ferric chloride, if your doing a pcb with traces 0.4mm and bigger by all means heat it to speed things up then wash it off with water,,,,,
however if you're doing pcb's with traces 0.40mm and smaller i've found actaully not heating it and using it straight out of the bottle at room temp is actaully better.... it still seems to chew away at those large areas as quickly is if heated but it won't destroy those finer traces and etch away under the photo resist layer that make those up as quickly
also bear in mind that increasing the size of some of your traces is somtimes also nessessary depending on how well the ink from you inkjet blocks the light
SilentScreamer
Senior Member
Personally I find spraying the paper with something like WD40 (or any other aerosol lubricant) make the paper more transparent and the UV time shorter.
demonicpicaxeguy
Senior Member
yep plain white paper,dpa
So in step 1 you're printing onto completely normal paper? Sounds nice'n'easy....
i have tried making it translucent with wd40 and it does cut down the exposuretime but i'm too cheap to keep going with it that way, i just wait the full 10ish minutes,
i looked at the cost of the transparency paper and almost cried it's redicilusly expensive and you can't just use normal inkjet ink on it either.......
demonicpicaxeguy
Senior Member
i've never used an exposure box, but the only problem i can see that some people may be having with them is that there might be so much uv light for the ink to block,
Mycroft2152
Senior Member
Sometimes the black inkjet ink is actually transparent to UV. Yellow seems to work better according to some posts on Homebrew_PCBs on Yahoo groups.i've never used an exposure box, but the only problem i can see that some people may be having with them is that there might be so much uv light for the ink to block,
Whatever homebrew pcb technique that you choose, it takes a bit of practice to get it right. Each process has its "gotchas".
demonicpicaxeguy
Senior Member
i think the only gotcha with mine is it can take upto 30mins to 40 mins to make 1 board , even the method i'm using now i went through a few dozen boards before i started to get boards that were usableSometimes the black inkjet ink is actually transparent to UV. Yellow seems to work better according to some posts on Homebrew_PCBs on Yahoo groups.
Whatever homebrew pcb technique that you choose, it takes a bit of practice to get it right. Each process has its "gotchas".
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Andrew Cowan
Senior Member
Add 'markers' to the top and bottom light masks. Place one mask onto the PCB (before etching), and drill where the marker is. Then flip the PCB over and align so the drilled hole matches up with the marker. put a bit of wire in the hole, and then UV expose.
A
A
Here is a website you might want to check out when it comes to making your own PCBs.
http://www.pcbfx.com. I came across this site about 6 months ago. I tried there product and I was hooked the first time I used it. There site also gives alot of information on making your own homemade PCBs. No, I'm not a dealer with them just a very satisfied customer in case anyone was wondering.
http://www.pcbfx.com. I came across this site about 6 months ago. I tried there product and I was hooked the first time I used it. There site also gives alot of information on making your own homemade PCBs. No, I'm not a dealer with them just a very satisfied customer in case anyone was wondering.
Mycroft2152
Senior Member
Already mentioned in Post #11Here is a website you might want to check out when it comes to making your own PCBs.
http://www.pcbfx.com. I came across this site about 6 months ago. I tried there product and I was hooked the first time I used it. There site also gives alot of information on making your own homemade PCBs. No, I'm not a dealer with them just a very satisfied customer in case anyone was wondering.
Cut the transfer film slightly larger than the pcb, and stick it down on the leading edge with sticky paper designed for laser printing labels. Print the layout to plain paper first, mark the paper so you know which way it went in the paper tray, stick the transfer film over the printed image with the sticky paper on the leading edge, back in the paper tray the way it was before, and print again.One disadvantage of toner transfer is that it's difficult to make just a small board - meaning you'll end up wasting the rest of the letter-sized transfer paper, which makes it a bit expensive.
A laminator with adjustable speed and heat, and spring loaded rollers beats a hand iron. Use the same sticky paper to fasten the leading edge of the transfer film to the pcb.
Amanda
demonicpicaxeguy
Senior Member
i've been down that special transfer film/paper road before, personally i think they are almost akin to snake oil and really still limited to dip and largish smd traces, i'm yet to actaully see anyone produce anything even close to somthing for a TQFP package, eg traces down to 0.2 mm or even 0.1mm with a toner transfer methodHere is a website you might want to check out when it comes to making your own PCBs.
http://www.pcbfx.com. I came across this site about 6 months ago. I tried there product and I was hooked the first time I used it. There site also gives alot of information on making your own homemade PCBs. No, I'm not a dealer with them just a very satisfied customer in case anyone was wondering.
Mycroft2152
Senior Member
DPG,i've been down that special transfer film/paper road before, personally i think they are almost akin to snake oil and really still limited to dip and largish smd traces, i'm yet to actaully see anyone produce anything even close to somthing for a TQFP package, eg traces down to 0.2 mm or even 0.1mm with a toner transfer method
It all depends on how fine a pcb that you want to make. For TQFP packages, I would go with a commercial board with solder mask.
But if you look at most of the pcbs posted here on the forum, 0.1" grids and DIP's are the rule. Toner transfer is more than adequate and is the easiest and cheapest way to get started.
You have to determine which pcb process is best for you.
Myc
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