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URL Links for PCB Learning..

URL Links for PCB Learning..

2010-08-01 by Athar Kaludi

Hi All

I found these links useful for PCB fabrication learning. Very descriptive and explanatory

http://www.siongboon.com/projects/2005-09-07_home_pcb_fabrication/
http://www.cibs.co.uk/etch/x9.html

In addition the below link is for knowledge on chemicals used in Photo resist - developers - etching 

http://nautarch.tamu.edu/crl/conservationmanual/File2.htm

http://books.google.co.uk/books?id=pqkR3Po010sC&pg=PA434&lpg=PA434&dq=potassium+carbonate+developer&source=bl&ots=dgODbYZ9Ff&sig=SCOiojORf9gPCUcvFGGO6vFwGVY&hl=en&ei=FtxVTOudNca9rAeJn-HyAw&sa=X&oi=book_result&ct=result&resnum=8&ved=0CDoQ6AEwBw#v=onepage&q=potassium%20carbonate%20developer&f=false

I found the link while searching on Potassium Carbonate to be used as developer. ? Comments welcome.
I am researching Photo-resist chemistry - Any link and info welcome.

Regards
Athar Kaludi
Pakistan

"1100 people lost their live in recent floods - Help them generously "
http://news.yahoo.com/s/ap/20100801/ap_on_re_as/as_pakistan_floods



      

[Non-text portions of this message have been removed]

Re: URL Links for PCB Learning..

2010-08-02 by bebx2000

--- In Homebrew_PCBs@yahoogroups.com, Athar Kaludi <ceo_premium@...> wrote:
>
> Hi All
> 
> I found these links useful for PCB fabrication learning. Very descriptive and explanatory
> 
> http://www.siongboon.com/projects/2005-09-07_home_pcb_fabrication/
> http://www.cibs.co.uk/etch/x9.html
> 
> In addition the below link is for knowledge on chemicals used in Photo resist - developers - etching 


Athar,

I am having a bit of difficulty understanding your objective. If you are researching modern photoresists, you need a PhD in organic chemistry to understand the literature and all of the formulations are highly proprietary, requiring exotic organic chemicals not readily available to the individual. For hobbyist PCB making, dry film for photo imaging is really the only way to proceed. It is comparatively cheap and readily available (MG chemicals, Puretch from Cape Fear Press ...). It just doesn't make too much sense to spend a lot of time on homebrewed photoresist. If you can devise a formulation for a resist that can be used in an inkjet, then that is another story.

If you are simply interested in the historical photo imaging processes, this is great. I find the subject fascinating. You might look at the APUG Forum, for alternative photographic processes.

In my post to you relative to dichromated gelatin, my main intent was to point to a patent which gives a recipe and process for a photo imageable solder mask that is accessable to the hobbyist. Solder mask is not cheap and is not available in small quantities. There seems to be great lament among DIY PCB makers about the lack of solder mask to nicely finish their boards. I suggest that this might be a fruitful area for your research.

N.B. For those frightened by ammonium dichromate, the cited patent uses diazo for the sensitizer.

Baxter

Re: URL Links for PCB Learning..

2010-08-03 by fredbutz

I'm having issues understanding as well.

But I find using laminated dry film photoresist to be a very easy process for home use.  The only hard part is finding a place to get the dry film material in small quantities.

I've been buying it from a guy on EBay.  I use a simple laminator and simple chemicals available at the grocery store (washing soda) for processing.  You can make your own UV exposure unit if you want, or pick one up for under $100 on EBay.

It is much easier and has much better results then any other process I've used (except mechanical etching.)

Re: URL Links for PCB Learning..

2010-08-03 by Howard Chester

Hello Fred, As a newbie to the group the laminated dry film photo resist has piqued my interest. Listening to various posts on laser vs inkjet, paper transfer methods ect, this sounds ideal for me. Any advice and/or links on this process would be greatly appreciated. I recently tried the "press n peel" method with the blue plastic type, but with limited success (could not produce a viable board-this maybe just me !), chester


 



  






      

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Re: URL Links for PCB Learning..

2010-08-03 by coronasensei

Hi Howard,
just though i'd chip in here also. Basically any technique has it's quirks and issues to get used to. There will be lots of testing and practice initially but once you get the difficulties sorted out making boards can be quick and cheap, to the point I never use prototyping board these days, I find it quicker to just make a custom pcb.

The main question to answer first is what sort of accuracy you need. My boards these days usually use down to 0.2mm (8mil) tracks which can be difficult, but achievable, with both photographic and toner transfer. If you're doing much more simple stuff I find toner transfer to be quicker and cheaper, and less prone to failure, but photographic is easier to get much finer/thinner tracks. (I usually use photographic lately).

I used to do a lot of transfer, initially with the blue stuff then moving on to photo paper. Seeing as you've already got some transfer stuff left you should give it another go. The main things you need to do to make transfer work is get the copper very very clean. Scrub with one of the green kitchen scourers (don't use it in kitchen afterwards!) to remove all the oxide and give the surface some slight texture for the toner to grab to, then clean it with turps. Turps works great because it removes any impurities and the slight fumes left afterwards helps melt the toner into the surface. wipe it down (paper towel) to the point that the surface looks dry, leaving it wet will make the toner run. whatever you do, at this point, do not touch the surface with fingers, keep to the edges. After that the main trick is getting the temperature and pressure right during the actual transfer, this takes practice. I ended up using a laminator and blowing it with a heat gun (this was with paper, which takes a little more effort to get the heat right though). I passed through laminator multiple times (trial and error). Then the for paper it's soak in water to release. With the blue film you have to be careful not to get it too hot or it'll wrinkle up. Don't try to pull the film/paper off until it's cold either.

Photo method, I just buy the pcb pre-coated, kinston brand. only problem with pre-coated is if you get a bad exposure/develop you've got useless pcb. with toner transfer or dry film a bad resist transfer means you just have to scrub the board clean and try again. 
My main difficulties with photographic is getting a good dark print onto a transparency, which comes down the the quality of the printer. Then I expose with diy light box (4 x 30mm uv ccfl tubes sitting in a cardboard box, timing for me is about 90 seconds) before developing in supermarket brand caustic soda (no-name drain cleaner). This takes practice to get the strength right, too weak and it wont develop, too strong and it'll take everything off, again trial and error, but only about 20 grains to just enough water to just cover the board. Once you're used to it it's as cheap as it gets and doesn't go off like most commercial developers. Just don't get it on skin, let alone eyes.

I've you've got somewhere to keep a tank of etchant (ie shed/garage), I suggest buying one of the proper vertical tanks(with heater and bubbler) and making up a batch of cupric chloride. It basically lasts forever, actually making more etchant as you use it. http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html
I've never does specific gravity tests or measured the chemistry of mine, basically just started it off with a little bit (ie about a cm in bottom of tank) of used other etchant (ammonium chloride) to get some copper ions in the fluid, then top up with acid and a hunk of copper (some wire) and set it bubbling. I don't remember how long it took but eventually it was green and worked to etch boards. when it gets brown after etching it just needs bubbling to turn it green again, if you start getting sludge settling in bottom of tank it needs to be topped up with acid. filter the sludge out first then add acid and keep using. My tank's been going for about 3 years now.

Anyway this got a lot longer than I expected, hope it helps!

Andrew

Re: URL Links for PCB Learning..

2010-08-03 by twb8899

--- In Homebrew_PCBs@yahoogroups.com, "fredbutz" <fredbutz@...> wrote:
>
> I'm having issues understanding as well.
> 
> But I find using laminated dry film photoresist to be a very easy process for home use.  The only hard part is finding a place to get the dry film material in small quantities.
> 
> I've been buying it from a guy on EBay.  I use a simple laminator and simple chemicals available at the grocery store (washing soda) for processing.  You can make your own UV exposure unit if you want, or pick one up for under $100 on EBay.
> 
> It is much easier and has much better results then any other process I've used (except mechanical etching.)
>

I use a DuPont hot roll laminator to apply dry film photo resist and can supply FR-4 copper clad material with the dry laminated. All you would have to do is UV expose, develop, etch and drill. Send me an email if you have any interest.  Tom

Re: [Homebrew_PCBs] Re: URL Links for PCB Learning..

2010-08-03 by Alessio Sangalli

On 08/03/2010 04:07 AM, coronasensei wrote:

> stuff left you should give it another go. The main things you need to
> do to make transfer work is get the copper very very clean. Scrub
> with one of the green kitchen scourers (don't use it in kitchen
> afterwards!) to remove all the oxide and give the surface some slight
> texture for the toner to grab to, then clean it with turps. Turps

I disagree with this. I was doing like you said, but I think it was at 
least just unnecessary, and in some cases I suspect it made 
solderability somewhat worse. Just use a shop cloth and acetone or heavy 
duty flux remover to clean the copper clad; at least, it works for me :)

With my printer (Richo 2000) and my laminator (an unmodified one I 
bought off the internet) I have virtually perfect results; smallest I 
used so far is 10mil traces.


> blowing it with a heat gun (this was with paper, which takes a little
> more effort to get the heat right though). I passed through laminator
> multiple times (trial and error). Then the for paper it's soak in

I normally pass it 8-10 times, with a "the more, the marrier" approach. 
I suspect only 3 or 4 times would be enough...

Maybe I ended up having a very good printer/laminator combo?

bye
as

Re: URL Links for PCB Learning..

2010-08-03 by coronasensei

--- In Homebrew_PCBs@yahoogroups.com, Alessio Sangalli <alesan@...> wrote:

> 
> Maybe I ended up having a very good printer/laminator combo?
> 

Annoyingly this is often a case with toner transfer, the differences in otherwise compatible equipment does make a difference. I noticed a massive difference once when we got new toner for my printer, it just didn't stick well anymore - it just so happened that this was cheap refill toner which didn't print as heavily/evenly either. If you go the photo paper for transfer it can be very cheap but again the differences between brand/type of papers is enormous.
I was also using a bottom dollar laminator, which I'm sure wont have the heat output of a decent brand one, hence the extra heat gun application. The problem with too much heat however is that paper blackens and blue stuf warps as mentioned, and even the toner can squash and spread if it's too hot, so it's a balancing act of getting the process right for your equipment.

I do agree to an extent with the excessiveness of my cleaning process, but I find it best to overdo it for a start then try simplifying it from there. I found turps to work better than acetone because of the residue, and I prefer to limit my exposure to acetone! But yeah you certainly need to clean the board well afterwards to solder to it.

I used to keep a solder bath (camping oven, frypan, lots of plumbing solder bars) for tinning the board after etching; flux, dip, wipe with windscreen squeegie, but that was when I had a fumer cupboard to keep it in. Now I use cool-amp silver plating powder, it's amazing. Only catch is silver can tarnish just as bad as copper. Still worth it though I feel, and looks real nice.

speaking of soldering, I find supermarket ascorbic (citric) acid, the stuff for baking that comes in granules, works wonders as a water clean flux when mixed in water and used from a spray bottle, it's cheap and safer than most commercial ones. spray it onto dirty copper and it'll brighten before your eyes!

Andrew

Re: [Homebrew_PCBs] Re: URL Links for PCB Learning..

2010-08-03 by Dave Garfield

Hi, Alessio and the group!
 
Just wanted to add to Alessio's last paragraph... Citric Acid, which I believe 
would be wonderful for cleaning copper, is also found in grocery stores under 
the name of "Sour Salt", and is usually with the baking supplies.  I know that 
it preserves dried fruit ever so well, and I'm sure that it would make an 
excellent copper cleaner.
 
Thanks!
 
Dave Garfield - contemplating "sour salt" in the "wilds" of Colorado...


________________________________
Show quoted textHide quoted text
From: coronasensei <coronasensei@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Tue, August 3, 2010 3:21:59 PM
Subject: [Homebrew_PCBs] Re: URL Links for PCB Learning..



--- In Homebrew_PCBs@yahoogroups.com, Alessio Sangalli <alesan@...> wrote:


...I do agree to an extent with the excessiveness of my cleaning process, but I 
find it best to overdo it for a start then try simplifying it from there. I 
found turps to work better than acetone because of the residue, and I prefer to 
limit my exposure to acetone! But yeah you certainly need to clean the board 
well afterwards to solder to it.

I used to keep a solder bath (camping oven, frypan, lots of plumbing solder 
bars) for tinning the board after etching; flux, dip, wipe with windscreen 
squeegie, but that was when I had a fumer cupboard to keep it in. Now I use 
cool-amp silver plating powder, it's amazing. Only catch is silver can tarnish 
just as bad as copper. Still worth it though I feel, and looks real nice.

speaking of soldering, I find supermarket ascorbic (citric) acid, the stuff for 
baking that comes in granules, works wonders as a water clean flux when mixed in 
water and used from a spray bottle, it's cheap and safer than most commercial 
ones. spray it onto dirty copper and it'll brighten before your eyes!

Andrew


      

[Non-text portions of this message have been removed]

Re: [Homebrew_PCBs] Re: URL Links for PCB Learning..

2010-08-04 by Matthew Andrews

For board cleaning, I have had very good results using "barkeepers
friend", a white powdered cleaning agent with oxalic acid as it's prime
active ingredient. just put some on a wet sponge and rub thoroughly on
the board, then rinse well before laminating. of course as always never
touch the board with bare hands after cleaing.

-Matt

coronasensei wrote:
Show quoted textHide quoted text
>  
>
>
>
> --- In Homebrew_PCBs@yahoogroups.com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, Alessio Sangalli
> <alesan@...> wrote:
>
> >
> > Maybe I ended up having a very good printer/laminator combo?
> >
>
> Annoyingly this is often a case with toner transfer, the differences
> in otherwise compatible equipment does make a difference. I noticed a
> massive difference once when we got new toner for my printer, it just
> didn't stick well anymore - it just so happened that this was cheap
> refill toner which didn't print as heavily/evenly either. If you go
> the photo paper for transfer it can be very cheap but again the
> differences between brand/type of papers is enormous.
> I was also using a bottom dollar laminator, which I'm sure wont have
> the heat output of a decent brand one, hence the extra heat gun
> application. The problem with too much heat however is that paper
> blackens and blue stuf warps as mentioned, and even the toner can
> squash and spread if it's too hot, so it's a balancing act of getting
> the process right for your equipment.
>
> I do agree to an extent with the excessiveness of my cleaning process,
> but I find it best to overdo it for a start then try simplifying it
> from there. I found turps to work better than acetone because of the
> residue, and I prefer to limit my exposure to acetone! But yeah you
> certainly need to clean the board well afterwards to solder to it.
>
> I used to keep a solder bath (camping oven, frypan, lots of plumbing
> solder bars) for tinning the board after etching; flux, dip, wipe with
> windscreen squeegie, but that was when I had a fumer cupboard to keep
> it in. Now I use cool-amp silver plating powder, it's amazing. Only
> catch is silver can tarnish just as bad as copper. Still worth it
> though I feel, and looks real nice.
>
> speaking of soldering, I find supermarket ascorbic (citric) acid, the
> stuff for baking that comes in granules, works wonders as a water
> clean flux when mixed in water and used from a spray bottle, it's
> cheap and safer than most commercial ones. spray it onto dirty copper
> and it'll brighten before your eyes!
>
> Andrew
>
>

Re: URL Links for PCB Learning..

2010-08-10 by fredbutz

Cleaning the board with Barkeepers Friend.

http://voodooengineering.com/index.php/pcbprocess/plating/70-plating-step-1-cleaning-the-pc-board

I was happy to find this product in our local grocery store.
It is great.

--- In Homebrew_PCBs@yahoogroups.com, Matthew Andrews <matt@...> wrote:
Show quoted textHide quoted text
>
> For board cleaning, I have had very good results using "barkeepers
> friend", a white powdered cleaning agent with oxalic acid as it's prime
> active ingredient. just put some on a wet sponge and rub thoroughly on
> the board, then rinse well before laminating. of course as always never
> touch the board with bare hands after cleaing.
> 
> -Matt
> 
> coronasensei wrote:
> >  
> >
> >
> >
> > --- In Homebrew_PCBs@yahoogroups.com
> > <mailto:Homebrew_PCBs%40yahoogroups.com>, Alessio Sangalli
> > <alesan@> wrote:
> >
> > >
> > > Maybe I ended up having a very good printer/laminator combo?
> > >
> >
> > Annoyingly this is often a case with toner transfer, the differences
> > in otherwise compatible equipment does make a difference. I noticed a
> > massive difference once when we got new toner for my printer, it just
> > didn't stick well anymore - it just so happened that this was cheap
> > refill toner which didn't print as heavily/evenly either. If you go
> > the photo paper for transfer it can be very cheap but again the
> > differences between brand/type of papers is enormous.
> > I was also using a bottom dollar laminator, which I'm sure wont have
> > the heat output of a decent brand one, hence the extra heat gun
> > application. The problem with too much heat however is that paper
> > blackens and blue stuf warps as mentioned, and even the toner can
> > squash and spread if it's too hot, so it's a balancing act of getting
> > the process right for your equipment.
> >
> > I do agree to an extent with the excessiveness of my cleaning process,
> > but I find it best to overdo it for a start then try simplifying it
> > from there. I found turps to work better than acetone because of the
> > residue, and I prefer to limit my exposure to acetone! But yeah you
> > certainly need to clean the board well afterwards to solder to it.
> >
> > I used to keep a solder bath (camping oven, frypan, lots of plumbing
> > solder bars) for tinning the board after etching; flux, dip, wipe with
> > windscreen squeegie, but that was when I had a fumer cupboard to keep
> > it in. Now I use cool-amp silver plating powder, it's amazing. Only
> > catch is silver can tarnish just as bad as copper. Still worth it
> > though I feel, and looks real nice.
> >
> > speaking of soldering, I find supermarket ascorbic (citric) acid, the
> > stuff for baking that comes in granules, works wonders as a water
> > clean flux when mixed in water and used from a spray bottle, it's
> > cheap and safer than most commercial ones. spray it onto dirty copper
> > and it'll brighten before your eyes!
> >
> > Andrew
> >
> >
>

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