Hello,
Since in this forum we are almost all hobbyist i thought to write here
I get bored of paper transfer method and time lost so i wanted to switch to the photoresist.
About the spray a lot of people use the positiv-20, it s 15 euros in europe, someone knows any alternative?
And for the transparent paper which one do you use? I don t want to buy the cheapest and then trough it
Any link or suggestion would be very appreciared 
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I follow this:
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Salt, vinegar, hyrdogen peroxide seems viable also
I send out for all my boards, I won't give up plated thru holes, stenciling, solder mask. And not having to not drill holes.
Once you have used a board house, you never go back to making your own.
Leo..
Really i asked a suggestion about which photoresist spray and transparent paper I should use... I never mentioned the etchant solution or how to do it
Wawa i agree, but what do you do when you need only 1 board?
aster94:
Wawa i agree, but what do you do when you need only 1 board?
I use my $3,000 CNC machine for that.
Leo..
I use tracing paper in a laser printer. I think it takes the toner a bit better than the acetate sheets some people use. I've had some really crisp results.
I buy pre-sensitised boards though, so I'm afraid I can't offer any advice with the spray stuff.
I like doing it myself. I enjoy the process.
Wawa:
I use my $3,000 CNC machine for that.
Leo..
You like to play the easy games ahahah one day i will have a cnc but this is not the day
GypsumFantastic:
I use tracing paper in a laser printer. I think it takes the toner a bit better than the acetate sheets some people use. I've had some really crisp results.I buy pre-sensitised boards though, so I'm afraid I can't offer any advice with the spray stuff.
I like doing it myself. I enjoy the process.
Could you give me a link or only the brand of this tracing paper?
To make the mask I use JetStar for Inkjets.
They also do one for laser printers. It is easier and better results to by the pre sensitized boards and I expose in a UV box from ebay.
aster94:
Wawa i agree, but what do you do when you need only 1 board?
Throw away the other 9 boards? Seeed just reduced their price to 5$ for 10 10x10cm^2 boards.
The only reason not to do that is the three weeks shipping time.
Some board houses have 5 boards for the same price as 10.
But this could reduce freight cost (which is the biggest killer).
Shop around.
Leo..
ElCaron:
Throw away the other 9 boards? Seeed just reduced their price to 5$ for 10 10x10cm^2 boards.
The only reason not to do that is the three weeks shipping time.
yep plus the 13€ for shipping, maybe in your country it is cheaper
aster94:
Could you give me a link or only the brand of this tracing paper?
It's Gateway brand but I don't think there's anything special about it. It was the first one I found in the stationery catalogue we use at work.
It's 90gsm which is just a bit thicker than standard copy/laser paper - I think that makes it a bit easier to handle.
I made my own exposure box using a UV CFL tube from a pond steriliser. It takes a long time to expose (about 15 minutes) but as I said, the results have been good.
I use my $3,000 CNC machine for that.
Leo..
Well, it's ok for some, but I bet you can' t do 4 thou track and spacing and 10 thou vias....
And how do you register top and bottom layers?
And as for mutilayers - that's tricky.
I've etched my own in the past, but professionally made boards are so good and cheap I woudn't bother these days.
And maybe the slow boat is partially a good thing - it makes you check thoroughly before ordering..
Allan
I would second the use of pre sensitised boards.
The spray on stuff i found to be finnicy, and have not used it for 30 years or so.
aster94:
yep plus the 13€ for shipping, maybe in your country it is cheaper
At seeed, I just paid 11US$ and 13US$ for shipping to Germany, for 20 boards each. So one board for 10US$=9€, if you throw away 9 from each design. Still worth it for me.
I actually found the solution for plated through holes at a house remodel I did. The previous owners left behind some old electronics parts, I'm guessing from the 60's/70's. In there I found a vial of what looked like rivets. On closer inspection, there were 2 sizes, in which one fit perfectly into the other.. The hole through the center just happens to be the right size for through hole parts. I would really like to locate more of these, as I only have about 30 left.
As for the boards, I just use the pre-sensitized boards, standard transparency sheets, and an Ott-light to expose them. 8 minutes does the trick, and I'm using downwards of .012 traces. I find temperature is key for the whole thing.
allanhurst:
Well, it's ok for some, but I bet you can' t do 4 thou track and spacing and 10 thou vias....
And how do you register top and bottom layers?
And as for mutilayers - that's tricky.
The CNC is only used for crude single layer things. The power stuff you do on strip board.
I started with rolls of 0.5-1mm wide etch resistant tape and an etch resistant drawing pen.
Then etch resistant rub-on transfers (pads and tracks).
Then moved to spray-on photoresist. Messy, smelly (has to be baked on), oneven, dust in it, etc.
Then the pre-fab photo sensitive boards. Then the iron-on transfer sheets (bad).
I think I produced the best boards with etch resistant transfers. I think it was "Letraset".
Not sure if you still can get that (I'm talking 30+ years ago).
allanhurst:
...professionally made boards are so good and cheap I woudn't bother these days.
And maybe the slow boat is partially a good thing - it makes you check thoroughly before ordering..
When your design skill improve, it's indeed the only way.
Leo..
In mobile phone design , using 6 or 8 layer boards 1.2mm thick, full of layout critical RF stuff and BGAs with microvias etc, where every 'spin' costs an awful lot, I always insisted ( however loudly the management yelled about delays ) on a full day of team review before finally releasing the design.
Found a lot of silly errors.
Allan.
tinman13kup:
. In there I found a vial of what looked like rivets. On closer inspection, there were 2 sizes, in which one fit perfectly into the other.. The hole through the center just happens to thing.
Sounds like through hole rivets , Farnell used to do them.
Csn be found on ebay.
