Chemical for PCB fabrication
IamSmooth, Mon Sept 15 2014, 12:19AMI use positive photoresist and use sodium metasilicate pentahydrate to remove the non-fixed material. Would plain store-bought sodium hydroxide work just as well? I believe I just need a basic solution to remove the unfixed photoresist, right?
Also, to remove the copper I am using ammonium persulfate. Can I use sodium bisulphate, which I can get much cheaper.
Re: Chemical for PCB fabrication
Patrick, Mon Sept 15 2014, 03:03AM
im trying to remember organic chemistry, but I think the ammonium ion plays a part...
Patrick, Mon Sept 15 2014, 03:03AM
im trying to remember organic chemistry, but I think the ammonium ion plays a part...
Re: Chemical for PCB fabrication
IamSmooth, Mon Sept 15 2014, 03:07AM
I've got a bucket of sodium bisulfate. I'm going to try it tomorrow and see what happens.
I have enough for my pool. I can spare some for a small etch tank.
IamSmooth, Mon Sept 15 2014, 03:07AM
I've got a bucket of sodium bisulfate. I'm going to try it tomorrow and see what happens.
I have enough for my pool. I can spare some for a small etch tank.
Re: Chemical for PCB fabrication
Steve Conner, Mon Sept 15 2014, 08:26AM
I always used sodium hydroxide to develop the photoresist and ferric chloride for the etching.
Steve Conner, Mon Sept 15 2014, 08:26AM
I always used sodium hydroxide to develop the photoresist and ferric chloride for the etching.
Re: Chemical for PCB fabrication
mikeselectricstuff, Mon Sept 15 2014, 09:36PM
Silicate based developers are much better then hydroxide - the margin between "develop" and "strip" is very high, If nothing else this means it isn't significantly temperature sensitive.
And made-up solution has indefinite shelf-life.
mikeselectricstuff, Mon Sept 15 2014, 09:36PM
Silicate based developers are much better then hydroxide - the margin between "develop" and "strip" is very high, If nothing else this means it isn't significantly temperature sensitive.
And made-up solution has indefinite shelf-life.
Re: Chemical for PCB fabrication
IamSmooth, Mon Sept 15 2014, 10:21PM
I tried 3% hydroxide and it was talking too long. Are there any other alternatives than sodium metasilicate that are just as good?
IamSmooth, Mon Sept 15 2014, 10:21PM
mikeselectricstuff wrote ...
Silicate based developers are much better then hydroxide - the margin between "develop" and "strip" is very high, If nothing else this means it isn't significantly temperature sensitive.
And made-up solution has indefinite shelf-life.
Silicate based developers are much better then hydroxide - the margin between "develop" and "strip" is very high, If nothing else this means it isn't significantly temperature sensitive.
And made-up solution has indefinite shelf-life.
I tried 3% hydroxide and it was talking too long. Are there any other alternatives than sodium metasilicate that are just as good?
Re: Chemical for PCB fabrication
2Spoons, Tue Sept 16 2014, 01:39AM
persulphate and bisulphate are two very different animals. I've found ferric chloride gives a cleaner, faster etch. Only downside is its messy.
2Spoons, Tue Sept 16 2014, 01:39AM
persulphate and bisulphate are two very different animals. I've found ferric chloride gives a cleaner, faster etch. Only downside is its messy.
Re: Chemical for PCB fabrication
IamSmooth, Tue Sept 16 2014, 02:21AM
Yes, ammonium persulfate is clean.
IamSmooth, Tue Sept 16 2014, 02:21AM
Yes, ammonium persulfate is clean.
Re: Chemical for PCB fabrication
mikeselectricstuff, Tue Sept 16 2014, 08:59AM
silicate/hydroxide is for developing, not etching!
The nice thing about silicate is you can mix it strong enough to develop as fast as 10 seconds, but not strip after a minute.
Different brands of photoresist can vary greatly in sensitivity & develop time so some experimentation is needed.
mikeselectricstuff, Tue Sept 16 2014, 08:59AM
silicate/hydroxide is for developing, not etching!
The nice thing about silicate is you can mix it strong enough to develop as fast as 10 seconds, but not strip after a minute.
Different brands of photoresist can vary greatly in sensitivity & develop time so some experimentation is needed.
Re: Chemical for PCB fabrication
Conundrum, Tue Sept 16 2014, 05:21PM
I've used persulphate, but it does need gentle heating, agitating and air bubbling to do anything.
Some folks have used 6% peroxide and weak hydrochloric, apparently Parazone drain cleaner works but I ended up using diluted HCl.
Always remember "acid to water, do as you oughta". NOT the other way around unless you want a trip to A&E.
Kind regards, -A.
disclaimer: May contain nuts.
Conundrum, Tue Sept 16 2014, 05:21PM
I've used persulphate, but it does need gentle heating, agitating and air bubbling to do anything.
Some folks have used 6% peroxide and weak hydrochloric, apparently Parazone drain cleaner works but I ended up using diluted HCl.
Always remember "acid to water, do as you oughta". NOT the other way around unless you want a trip to A&E.
Kind regards, -A.
disclaimer: May contain nuts.
Re: Chemical for PCB fabrication
dexter, Tue Sept 16 2014, 05:48PM
i use the same and it works perfect
for the concentration of the sodium hydroxide i use 4-5 flakes (~1cm^2) and 250 ml water (empiric testing). It takes ~20 sec to develop
dexter, Tue Sept 16 2014, 05:48PM
Steve Conner wrote ...
I always used sodium hydroxide to develop the photoresist and ferric chloride for the etching.
I always used sodium hydroxide to develop the photoresist and ferric chloride for the etching.
i use the same and it works perfect
for the concentration of the sodium hydroxide i use 4-5 flakes (~1cm^2) and 250 ml water (empiric testing). It takes ~20 sec to develop
Re: Chemical for PCB fabrication
Daedronus, Wed Sept 17 2014, 09:00AM
Sodium hydroxide is the worst choice for developing etch masks.
Normally sodium carbonate is used, unless the product specifically calls for sodium hydroxide.
Easily made from baking powder by thermal decomposition.
For most film masks this should be true.
Only product that I know of that uses sodium hydroxide is the Positive 20 aerosol.
Daedronus, Wed Sept 17 2014, 09:00AM
Sodium hydroxide is the worst choice for developing etch masks.
Normally sodium carbonate is used, unless the product specifically calls for sodium hydroxide.
Easily made from baking powder by thermal decomposition.
For most film masks this should be true.
Only product that I know of that uses sodium hydroxide is the Positive 20 aerosol.
Re: Chemical for PCB fabrication
Hazmatt_(The Underdog), Thu Sept 18 2014, 04:14AM
MG Chemicals Positive Etch:
Sodium Hydroxide, approx. 0.9M (last time I titrated it years ago)
and Ferric Chloride Etch.
All of it takes some practice, but it works.
The Hydroxide, sold as a Concentrate, tells you to dilute it on the bottle. If you pour it straight onto the board, it will remove your mask.
All you have to do is Follow the directions.
Hazmatt_(The Underdog), Thu Sept 18 2014, 04:14AM
MG Chemicals Positive Etch:
Sodium Hydroxide, approx. 0.9M (last time I titrated it years ago)
and Ferric Chloride Etch.
All of it takes some practice, but it works.
The Hydroxide, sold as a Concentrate, tells you to dilute it on the bottle. If you pour it straight onto the board, it will remove your mask.
All you have to do is Follow the directions.
Re: Chemical for PCB fabrication
Daedronus, Thu Sept 18 2014, 08:31AM
Most negative etch masks films I have seen on eBay and such specificity use sodium carbonate for developing and sodium hydroxide for stripping.
In the end check the manufacturer's data, both chemicals are easily accessible.
Daedronus, Thu Sept 18 2014, 08:31AM
Most negative etch masks films I have seen on eBay and such specificity use sodium carbonate for developing and sodium hydroxide for stripping.
In the end check the manufacturer's data, both chemicals are easily accessible.
Re: Chemical for PCB fabrication
IamSmooth, Thu Sept 18 2014, 09:32PM
I'm etching now with ammonium persulfate.
I use the sodium silicate to remove positive resist and it works quite well. I'm going to try NaOH and compare them.
IamSmooth, Thu Sept 18 2014, 09:32PM
I'm etching now with ammonium persulfate.
I use the sodium silicate to remove positive resist and it works quite well. I'm going to try NaOH and compare them.
Re: Chemical for PCB fabrication
Hazmatt_(The Underdog), Fri Sept 19 2014, 12:27AM
When developing, make sure you agitate the board.
Don't just drop it in and stare at it, and hope it develops, it doesn't work that way.
Agitate the solution and it will develop fairly fast, and rinse with water.
I ususally use a large pan and rock it back and forth.
Hazmatt_(The Underdog), Fri Sept 19 2014, 12:27AM
When developing, make sure you agitate the board.
Don't just drop it in and stare at it, and hope it develops, it doesn't work that way.
Agitate the solution and it will develop fairly fast, and rinse with water.
I ususally use a large pan and rock it back and forth.
Re: Chemical for PCB fabrication
IamSmooth, Fri Sept 19 2014, 01:50AM
I have a bubbler. I submerge the system in near-boiling water to passively heat the solution. I get it developed in minutes.
IamSmooth, Fri Sept 19 2014, 01:50AM
I have a bubbler. I submerge the system in near-boiling water to passively heat the solution. I get it developed in minutes.
Re: Chemical for PCB fabrication
Daedronus, Fri Sept 19 2014, 08:32AM
what etch mask do you you IamSmooth?
Daedronus, Fri Sept 19 2014, 08:32AM
what etch mask do you you IamSmooth?
Re: Chemical for PCB fabrication
IamSmooth, Fri Sept 19 2014, 09:59PM
I wonder if I should make a video on all of this. Here is my process:
I design the tracings using PCB Wizard, which I believe is from the UK. I print the tracings out on transparency film and expose my PCB with it in an exposure unit. I currently develop the positive resist in sodium silicate to leave the tracings on the copper. I develop in ammonium persulfate.
I then use a drill press (but now I am using a micro mill, which allows me to control the movement by 0.001") to make the holes.
Would anyone want me to make a video for this? There are videos out there already; I don't know if I'd contribute much more.
IamSmooth, Fri Sept 19 2014, 09:59PM
I wonder if I should make a video on all of this. Here is my process:
I design the tracings using PCB Wizard, which I believe is from the UK. I print the tracings out on transparency film and expose my PCB with it in an exposure unit. I currently develop the positive resist in sodium silicate to leave the tracings on the copper. I develop in ammonium persulfate.
I then use a drill press (but now I am using a micro mill, which allows me to control the movement by 0.001") to make the holes.
Would anyone want me to make a video for this? There are videos out there already; I don't know if I'd contribute much more.
Re: Chemical for PCB fabrication
IamSmooth, Sun Sept 21 2014, 12:13AM
What are the rest of you doing for vias when you have a double-sided board? I've seen conductive gel/epoxy and videos for copper electroplating.
Right now I'm just soldering small leads through the hole on both sides to make the connection, but I'm looking for a cleaner method.
IamSmooth, Sun Sept 21 2014, 12:13AM
What are the rest of you doing for vias when you have a double-sided board? I've seen conductive gel/epoxy and videos for copper electroplating.
Right now I'm just soldering small leads through the hole on both sides to make the connection, but I'm looking for a cleaner method.
Re: Chemical for PCB fabrication
Patrick, Sun Sept 21 2014, 01:24AM
I use the same via method as you, so i cant help there. but ive done toner transfer and photo-resist, and i much prefer the toner method. Just dont buy a Brother copier or laser printer, it wont work. But to each his own.
EDIT: if im remembering there was a tiny mushroom-hollow-tube-like component, used for our purposes.
Patrick, Sun Sept 21 2014, 01:24AM
I use the same via method as you, so i cant help there. but ive done toner transfer and photo-resist, and i much prefer the toner method. Just dont buy a Brother copier or laser printer, it wont work. But to each his own.
Conundrum wrote ...
Always remember "acid to water, do as you oughta". NOT the other way around unless you want a trip to A&E.
You sure take the fun out of life...Always remember "acid to water, do as you oughta". NOT the other way around unless you want a trip to A&E.
EDIT: if im remembering there was a tiny mushroom-hollow-tube-like component, used for our purposes.
Re: Chemical for PCB fabrication
Hazmatt_(The Underdog), Sun Sept 21 2014, 04:45AM
Yes, those are called Eyelets, usually by Keystone.
Hazmatt_(The Underdog), Sun Sept 21 2014, 04:45AM
Yes, those are called Eyelets, usually by Keystone.
Re: Chemical for PCB fabrication
IamSmooth, Sun Sept 21 2014, 06:18PM
are eyelets worth using?
I see some machine on amazon, but I don't see the proper dyes for handling such small pieces of metal. Does anyone use one?
I guess I could make one on my lathe.
IamSmooth, Sun Sept 21 2014, 06:18PM
are eyelets worth using?
I see some machine on amazon, but I don't see the proper dyes for handling such small pieces of metal. Does anyone use one?
I guess I could make one on my lathe.
Re: Chemical for PCB fabrication
Patrick, Sun Sept 21 2014, 07:25PM
i think striaght through wires are better.
Patrick, Sun Sept 21 2014, 07:25PM
i think striaght through wires are better.
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