Homebrew PCBs

Hi All,
After looking at Craig's fasinating PCB spinning methods, an idea came to mind, seeing as the regular chemicals seem to be rare and expensive, has anyone tried silk screen printing emulsions? this in not the inks but the chemical used to make the pattern in a very fine mesh, the emulsion is spread over the mesh with a squeegy and after exposure to UV through the pattern[design] blocking transparency, the unexposed area is washed out with running water, the exposed area remains and is really pretty tough, is this resistant to etching chemicals? would this method work? has anyone tried?
There would be no need to "develop" the PCB, just wash off with water!!
I may be way off track with this but any comments and/or suggestions?

David

On 14/04/2012 21:24, David wrote:
> Hi All,
> After looking at Craig's fasinating PCB spinning methods, an idea came
> to mind, seeing as the regular chemicals seem to be rare and expensive,
> has anyone tried silk screen printing emulsions? this in not the inks
> but the chemical used to make the pattern in a very fine mesh, the
> emulsion is spread over the mesh with a squeegy and after exposure to UV
> through the pattern[design] blocking transparency, the unexposed area is
> washed out with running water, the exposed area remains and is really
> pretty tough, is this resistant to etching chemicals? would this method
> work? has anyone tried?
> There would be no need to "develop" the PCB, just wash off with water!!
> I may be way off track with this but any comments and/or suggestions?


PCBs were made that way at English Electric Ltd, Kidsgrove, when I was a 
student there in 1962. The pattern was created on a silk screen, it was 
placed in contact with the copper, and the resist was applied with a a 
squeegee.

Leon
-- 
Leon Heller
G1HSM

Leon -
 
But would the material use in the silkscreen stick to the copper clad and
serve as a resist after exposure?

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Leon Heller
Sent: Saturday, April 14, 2012 3:29 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Alternative photoresist chemicals - Idea?


  

On 14/04/2012 21:24, David wrote:
> Hi All,
> After looking at Craig's fasinating PCB spinning methods, an idea came
> to mind, seeing as the regular chemicals seem to be rare and expensive,
> has anyone tried silk screen printing emulsions? this in not the inks
> but the chemical used to make the pattern in a very fine mesh, the
> emulsion is spread over the mesh with a squeegy and after exposure to UV
> through the pattern[design] blocking transparency, the unexposed area is
> washed out with running water, the exposed area remains and is really
> pretty tough, is this resistant to etching chemicals? would this method
> work? has anyone tried?
> There would be no need to "develop" the PCB, just wash off with water!!
> I may be way off track with this but any comments and/or suggestions?

PCBs were made that way at English Electric Ltd, Kidsgrove, when I was a 
student there in 1962. The pattern was created on a silk screen, it was 
placed in contact with the copper, and the resist was applied with a a 
squeegee.

Leon
-- 
Leon Heller
G1HSM





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

Leon / Andrew,

Sorry, I dont think i made myself clear, I was suggesting the emulsion used in silk screen printing to be put directly onto the PCB using Craig's spinning method, not through a mesh, oven dry it, then expose using UV and circuit pattern on a transparency or tracing paper as normal, the exposed area would remain and the circuit washed off with water ready for etching, if that makes sense! I was also wondering if the resist would stand up to the etching chemicals? the main reason is, this type of emulsion is a lot cheaper and easier to get than the dedicated PCB stuff! 

David

--- In Homebrew_PCBs@yahoogroups.com, "Andrew Volk" <amvweb@...> wrote:

>
> Leon -
>  
> But would the material use in the silkscreen stick to the copper clad and
> serve as a resist after exposure?
> 
>   _____  
> 
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Leon Heller
> Sent: Saturday, April 14, 2012 3:29 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Alternative photoresist chemicals - Idea?
> 
> 
>   
> 
> On 14/04/2012 21:24, David wrote:
> > Hi All,
> > After looking at Craig's fasinating PCB spinning methods, an idea came
> > to mind, seeing as the regular chemicals seem to be rare and expensive,
> > has anyone tried silk screen printing emulsions? this in not the inks
> > but the chemical used to make the pattern in a very fine mesh, the
> > emulsion is spread over the mesh with a squeegy and after exposure to UV
> > through the pattern[design] blocking transparency, the unexposed area is
> > washed out with running water, the exposed area remains and is really
> > pretty tough, is this resistant to etching chemicals? would this method
> > work? has anyone tried?
> > There would be no need to "develop" the PCB, just wash off with water!!
> > I may be way off track with this but any comments and/or suggestions?
> 
> PCBs were made that way at English Electric Ltd, Kidsgrove, when I was a 
> student there in 1962. The pattern was created on a silk screen, it was 
> placed in contact with the copper, and the resist was applied with a a 
> squeegee.
> 
> Leon
> -- 
> Leon Heller
> G1HSM
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>

That would all depend on whether the silk screen emulsion stuff was UV sensitive and reacted the same way as normal UV resist, to actually stay on or wash off according to the pattern.

--- In Homebrew_PCBs@yahoogroups.com, "David" <dgh2259@...> wrote:

>
> Leon / Andrew,
> 
> Sorry, I dont think i made myself clear, I was suggesting the emulsion used in silk screen printing to be put directly onto the PCB using Craig's spinning method, not through a mesh, oven dry it, then expose using UV and circuit pattern on a transparency or tracing paper as normal, the exposed area would remain and the circuit washed off with water ready for etching, if that makes sense! I was also wondering if the resist would stand up to the etching chemicals? the main reason is, this type of emulsion is a lot cheaper and easier to get than the dedicated PCB stuff! 
> 
> David

If I recall correctly, the silk screen emulsion is UV sensitive. The 
question is if it can hold up under any of the commonly used PCB 
etchants like ferric chloride or
ammonium chloride, or even muriatic acid and hydrogen peroxide.

If so, you may have had a stroke of genius, if you can find a source for 
the silk screen emulsion.

Roland F. Harriston, P.D.
********************


tda7000 wrote:
>  
>
> That would all depend on whether the silk screen emulsion stuff was UV 
> sensitive and reacted the same way as normal UV resist, to actually 
> stay on or wash off according to the pattern.
>
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "David" <dgh2259@...> wrote:
> >
> > Leon / Andrew,
> >
> > Sorry, I dont think i made myself clear, I was suggesting the 
> emulsion used in silk screen printing to be put directly onto the PCB 
> using Craig's spinning method, not through a mesh, oven dry it, then 
> expose using UV and circuit pattern on a transparency or tracing paper 
> as normal, the exposed area would remain and the circuit washed off 
> with water ready for etching, if that makes sense! I was also 
> wondering if the resist would stand up to the etching chemicals? the 
> main reason is, this type of emulsion is a lot cheaper and easier to 
> get than the dedicated PCB stuff!
> >
> > David
>
> 



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

On 15-Apr-12 03:51, David wrote:
> Leon / Andrew,
> 
> Sorry, I dont think i made myself clear, I was suggesting the emulsion used in silk screen printing to be put directly onto the PCB using Craig's spinning method, not through a mesh, oven dry it, then expose using UV and circuit pattern on a transparency or tracing paper as normal, the exposed area would remain and the circuit washed off with water ready for etching, if that makes sense! I was also wondering if the resist would stand up to the etching chemicals? the main reason is, this type of emulsion is a lot cheaper and easier to get than the dedicated PCB stuff! 
> 
> David
> 

Something like:
<http://www.macdermidautotype.com/products/screen-films/capillex-films>

It was looong time that I used it to make screens for producing some
front panel foils. I may try someday :-) and feedback the findings.

-- 
Best Regards,
Zoran A. \u0160\u0107epanovi\u0107
zastos@...
http://zastos.com
+381 63 609-993

-..-
I may be a scwewy wabbit,
  but I'm not going to Alcatwaz!

On 15/04/2012 01:00, Andrew Volk wrote:
> Leon -
>
> But would the material use in the silkscreen stick to the copper clad and
> serve as a resist after exposure?

I think it was the same stuff that was used for ordinary silkscreen 
printing.

They couldn't produce very fine tracks with that process, but it didn't 
matter, as they weren't using ICs at that time.

Leon
-- 
Leon Heller
G1HSM

I do not know if the silk screen emulsion will stick and protect copper.  

I think resolution would be OK.  Many years ago I was silk screening text
and graphics with 7 mil lines.  The limitation was the silk screen mesh.

Bertho

From: David  Sent: Saturday, April 14, 2012 21:52



Leon / Andrew,

Sorry, I dont think i made myself clear, I was suggesting the emulsion used
in silk screen printing to be put directly onto the PCB using Craig's
spinning method, not through a mesh, oven dry it, then expose using UV and
circuit pattern on a transparency or tracing paper as normal, the exposed
area would remain and the circuit washed off with water ready for etching,
if that makes sense! I was also wondering if the resist would stand up to
the etching chemicals? the main reason is, this type of emulsion is a lot
cheaper and easier to get than the dedicated PCB stuff! 

David





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

Hi David,
 
Forty years ago I used homebrew photo resist based on chemicals used for silk screen printing. It was very cheep and worked just fine. You don’t need UV light and the “developer” is  regular water. This technology is worth if you have to manufacture many relatively large boards (15x20cm) at home.
 
The only problem was that the emulsions and the ferric chloride  must be kept in narrow tolerances like temperature and concentration. 
 
Unfortunately, I don’t have my archive records on hand to give you those recipes. 
 
Regards,
 
Vesko, AB8PG / LZ2WJ

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

Hi David,
 
Forty years ago I used homebrew photo resist based on chemicals used for silk screen printing. It was very cheep and worked just fine. You don’t need UV light and the “developer” is  regular water. This technology is worth if you have to manufacture many relatively large boards (15x20cm) at home.
 
The only problem was that the emulsions and the ferric chloride  must be kept in narrow tolerances like temperature and concentration. 
 
Unfortunately, I don’t have my archive records on hand to give you those recipes. 
 
Regards,
 
Vesko, AB8PG / LZ2WJ

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

Silk screen emulsion is UV sensitive, when exposed it becomes very hard,(i.e. To  block the printing inks) the unexposed area is simply washed off, ready for etching. I think I will give it a go, and give feedback when i've run a few tests! Many thanks to all who have so far offered suggestions
David

--- In Homebrew_PCBs@yahoogroups.com, "tda7000" <Tda7000@...> wrote:

>
> That would all depend on whether the silk screen emulsion stuff was UV sensitive and reacted the same way as normal UV resist, to actually stay on or wash off according to the pattern.
> 
> --- In Homebrew_PCBs@yahoogroups.com, "David" <dgh2259@> wrote:
> >
> > Leon / Andrew,
> > 
> > Sorry, I dont think i made myself clear, I was suggesting the emulsion used in silk screen printing to be put directly onto the PCB using Craig's spinning method, not through a mesh, oven dry it, then expose using UV and circuit pattern on a transparency or tracing paper as normal, the exposed area would remain and the circuit washed off with water ready for etching, if that makes sense! I was also wondering if the resist would stand up to the etching chemicals? the main reason is, this type of emulsion is a lot cheaper and easier to get than the dedicated PCB stuff! 
> > 
> > David
>

What I am thinking about:

 Forget about the "silk screen". which in most modern "silk screening" 
operations is actually a screen made of stainless steel, and can have a 
rather fine "mesh".

 Obtain the emulsion only, and apply it directly to the copper clad 
printed circuit material, NOT to a screen.

 Do imaging.

 Develop the emulsion.

 Etch the board.

This is not really "silk screening" per se. It is using the silk screen 
emulsion instead of Kodak KPR or any of the other now-unavailable photo 
resist materials.

The challenges are: Obtaining the emulsion.  Assuring that the emulsion 
will withstand the etch process.  Also, how well the emulsion will 
adhere to the
copper.

It seems to me that a long time ago, I was able to obtain a 
photosensitive material that was designed for "silk" screen work that 
was a polymer, sold in a roll.
This material was applied to the wire or "silk" mesh, imaged and 
developed. I got the material at a graphics art supply store. I never 
really used it because
at that time Kodak KPR and competing emulsions were readily available 
and the KPR process was more familiar to me.

The new trick would be to apply this "silk" screen emulsion directly to 
a copper surface.

Not "silk" screening.

But then, we already have readily available dry film resist materials 
(sheets), and  PC  board stock that is already  coated with dry  film  
resist.
 
Roland F. Harriston, P.D.
*******************




David wrote:
>  
>
> Silk screen emulsion is UV sensitive, when exposed it becomes very 
> hard,(i.e. To block the printing inks) the unexposed area is simply 
> washed off, ready for etching. I think I will give it a go, and give 
> feedback when i've run a few tests! Many thanks to all who have so far 
> offered suggestions
> David
>
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "tda7000" <Tda7000@...> wrote:
> >
> > That would all depend on whether the silk screen emulsion stuff was 
> UV sensitive and reacted the same way as normal UV resist, to actually 
> stay on or wash off according to the pattern.
> >
> > --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "David" <dgh2259@> wrote:
> > >
> > > Leon / Andrew,
> > >
> > > Sorry, I dont think i made myself clear, I was suggesting the 
> emulsion used in silk screen printing to be put directly onto the PCB 
> using Craig's spinning method, not through a mesh, oven dry it, then 
> expose using UV and circuit pattern on a transparency or tracing paper 
> as normal, the exposed area would remain and the circuit washed off 
> with water ready for etching, if that makes sense! I was also 
> wondering if the resist would stand up to the etching chemicals? the 
> main reason is, this type of emulsion is a lot cheaper and easier to 
> get than the dedicated PCB stuff!
> > >
> > > David
> >
>
> 



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

Silk Screen Emulsion Source:
http://www.silkscreeningsupplies.com/diazo-photo-emulsion?gclid=CNDprfSXt68CFYYHRQodu2zWjQ


I have no idea if it works but would be interesting to find out.



On Sun, Apr 15, 2012 at 8:27 AM, Roland F. Harriston <rolohar@...>wrote:

> **
>
>
> What I am thinking about:
>
> Forget about the "silk screen". which in most modern "silk screening"
> operations is actually a screen made of stainless steel, and can have a
> rather fine "mesh".
>
> Obtain the emulsion only, and apply it directly to the copper clad
> printed circuit material, NOT to a screen.
>
> Do imaging.
>
> Develop the emulsion.
>
> Etch the board.
>
> This is not really "silk screening" per se. It is using the silk screen
> emulsion instead of Kodak KPR or any of the other now-unavailable photo
> resist materials.
>
> The challenges are: Obtaining the emulsion. Assuring that the emulsion
> will withstand the etch process. Also, how well the emulsion will
> adhere to the
> copper.
>
> It seems to me that a long time ago, I was able to obtain a
> photosensitive material that was designed for "silk" screen work that
> was a polymer, sold in a roll.
> This material was applied to the wire or "silk" mesh, imaged and
> developed. I got the material at a graphics art supply store. I never
> really used it because
> at that time Kodak KPR and competing emulsions were readily available
> and the KPR process was more familiar to me.
>
> The new trick would be to apply this "silk" screen emulsion directly to
> a copper surface.
>
> Not "silk" screening.
>
> But then, we already have readily available dry film resist materials
> (sheets), and PC board stock that is already coated with dry film
> resist.
>
> Roland F. Harriston, P.D.
> *******************
>
>
> David wrote:
> >
> >
> > Silk screen emulsion is UV sensitive, when exposed it becomes very
> > hard,(i.e. To block the printing inks) the unexposed area is simply
> > washed off, ready for etching. I think I will give it a go, and give
> > feedback when i've run a few tests! Many thanks to all who have so far
> > offered suggestions
> > David
> >
> > --- In Homebrew_PCBs@yahoogroups.com
> > <mailto:Homebrew_PCBs%40yahoogroups.com>, "tda7000" <Tda7000@...> wrote:
> > >
> > > That would all depend on whether the silk screen emulsion stuff was
> > UV sensitive and reacted the same way as normal UV resist, to actually
> > stay on or wash off according to the pattern.
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com
> > <mailto:Homebrew_PCBs%40yahoogroups.com>, "David" <dgh2259@> wrote:
> > > >
> > > > Leon / Andrew,
> > > >
> > > > Sorry, I dont think i made myself clear, I was suggesting the
> > emulsion used in silk screen printing to be put directly onto the PCB
> > using Craig's spinning method, not through a mesh, oven dry it, then
> > expose using UV and circuit pattern on a transparency or tracing paper
> > as normal, the exposed area would remain and the circuit washed off
> > with water ready for etching, if that makes sense! I was also
> > wondering if the resist would stand up to the etching chemicals? the
> > main reason is, this type of emulsion is a lot cheaper and easier to
> > get than the dedicated PCB stuff!
> > > >
> > > > David
> > >
> >
> >
>
> [Non-text portions of this message have been removed]
>
>  
>



-- 
If you ask me if it can be done. The answer is YES, it can always be done.
The correct questions however are... What will it cost, and how long will
it take?


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

Ulano was the company that made the stuff I purchased many years ago.
I think they also made a material called "Rubylith".
Old-time microstripline designers will remember this material.

As I recall, most silk screen inks were spirit-based, and the screen image
was not affected by the paint.

So, I'm thinking that the emulsion would most likely be immune to
most pc board etchants.

Someone should really get into this idea and see how it works.

Roland F. Harriston, P.D.
******************



Randall Morgan wrote:

> Silk Screen Emulsion Source:
> http://www.silkscreeningsupplies.com/diazo-photo-emulsion?gclid=CNDprfSXt68CFYYHRQodu2zWjQ
>
>
> I have no idea if it works but would be interesting to find out.
>
>
>
> On Sun, Apr 15, 2012 at 8:27 AM, Roland F. Harriston <rolohar@...>wrote:
>
>   
>> **
>>
>>
>>

What is the shelf life of silkscreen emulsion?  Do you have to mix the
emulsion with a sensitizer?

 

Jeff

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Roland F. Harriston
Sent: Sunday, April 15, 2012 11:59 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Re: Alternative photoresist chemicals - Idea?

 

  

Ulano was the company that made the stuff I purchased many years ago.
I think they also made a material called "Rubylith".
Old-time microstripline designers will remember this material.

As I recall, most silk screen inks were spirit-based, and the screen image
was not affected by the paint.

So, I'm thinking that the emulsion would most likely be immune to
most pc board etchants.

Someone should really get into this idea and see how it works.

Roland F. Harriston, P.D.
******************

Randall Morgan wrote:
> Silk Screen Emulsion Source:
>
http://www.silkscreeningsupplies.com/diazo-photo-emulsion?gclid=CNDprfSXt68C
FYYHRQodu2zWjQ
>
>
> I have no idea if it works but would be interesting to find out.
>
>
>
> On Sun, Apr 15, 2012 at 8:27 AM, Roland F. Harriston <rolohar@...
<mailto:rolohar%40comcast.net> >wrote:
>
> 
>> **
>>
>>
>> 





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

There are both types available, one ready mixed, [would imagine a shelf life of a couple of years] and a two part product, with a sensitizer, [that probably has a much longer shelf life] if i recall correctly, there are spirit based emulsions and water based emulsions, once exposed both are pretty tough. I also note Diazo make a product for very fine detail prints. As mentioned previously i will give it a go and report my findings.
David

--- In Homebrew_PCBs@yahoogroups.com, "Jeff Heiss" <jeff.heiss@...> wrote:

>
> What is the shelf life of silkscreen emulsion?  Do you have to mix the
> emulsion with a sensitizer?
> 
>  
> 
> Jeff
> 
>  
> 
>   _____  
> 
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Roland F. Harriston
> Sent: Sunday, April 15, 2012 11:59 AM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Re: Alternative photoresist chemicals - Idea?
> 
>  
> 
>   
> 
> Ulano was the company that made the stuff I purchased many years ago.
> I think they also made a material called "Rubylith".
> Old-time microstripline designers will remember this material.
> 
> As I recall, most silk screen inks were spirit-based, and the screen image
> was not affected by the paint.
> 
> So, I'm thinking that the emulsion would most likely be immune to
> most pc board etchants.
> 
> Someone should really get into this idea and see how it works.
> 
> Roland F. Harriston, P.D.
> ******************
> 
> Randall Morgan wrote:
> > Silk Screen Emulsion Source:
> >
> http://www.silkscreeningsupplies.com/diazo-photo-emulsion?gclid=CNDprfSXt68C
> FYYHRQodu2zWjQ
> >
> >
> > I have no idea if it works but would be interesting to find out.
> >
> >
> >
> > On Sun, Apr 15, 2012 at 8:27 AM, Roland F. Harriston <rolohar@...
> <mailto:rolohar%40comcast.net> >wrote:
> >
> > 
> >> **
> >>
> >>
> >> 
> 
> 
> 
> 
> 
> [Non-text portions of this message have been removed]
>

That's a good question as I was thinking about the same thing when I got a screen printing setup a few months ago, but haven't had time to even do more then open the box to make sure everything was in the kit...

--- In Homebrew_PCBs@yahoogroups.com, "David" <dgh2259@...> wrote:

>
> Hi All,
> After looking at Craig's fasinating PCB spinning methods, an idea came to mind, seeing as the regular chemicals seem to be rare and expensive, has anyone tried silk screen printing emulsions? this in not the inks but the chemical used to make the pattern in a very fine mesh, the emulsion is spread over the mesh with a squeegy and after exposure to UV through the pattern[design] blocking transparency, the unexposed area is washed out with running water, the exposed area remains and is really pretty tough, is this resistant to etching chemicals? would this method work? has anyone tried?
> There would be no need to "develop" the PCB, just wash off with water!!
> I may be way off track with this but any comments and/or suggestions?
> 
> David
>

I think the general concensus is it will probably work, using the spinning method to achieve a thin uniform layer and baking it for a short while, then expose as normal, one less chemical to use as unexposed resist just washes off, not sure how well the exposed area will stick to the copper clad though, a few experiments should wrap it up though!

Another interesting alternative to the various PCB and Silk Screen chemicals available is to make it yourself!

A mixture of Potassium Dichromate [or bichromate] and Egg yoke, or  dairy cream, will make a UV sensitive emulsion.[how this stands up to etching though........] not sure of the mixing ratios, but, it is toxic!! a carcinogenic, and chromium dermatitis are two of the more unpleasant results of getting in contact with the stuff!! it is sold on ebay amongst other places;

http://www.ebay.co.uk/itm/Potassio-bicromato-Kaliumdichromat-potassium-dichromate-/180861035286?pt=Laboratorio_e_Scienze_Mediche&hash=item2a1c286316

if anyone would like to experiment?..........

David



--- In Homebrew_PCBs@yahoogroups.com, "mark" <STRIPES97_USA@...> wrote:

>
> That's a good question as I was thinking about the same thing when I got a screen printing setup a few months ago, but haven't had time to even do more then open the box to make sure everything was in the kit...
> 
> --- In Homebrew_PCBs@yahoogroups.com, "David" <dgh2259@> wrote:
> >
> > Hi All,
> > After looking at Craig's fasinating PCB spinning methods, an idea came to mind, seeing as the regular chemicals seem to be rare and expensive, has anyone tried silk screen printing emulsions? this in not the inks but the chemical used to make the pattern in a very fine mesh, the emulsion is spread over the mesh with a squeegy and after exposure to UV through the pattern[design] blocking transparency, the unexposed area is washed out with running water, the exposed area remains and is really pretty tough, is this resistant to etching chemicals? would this method work? has anyone tried?
> > There would be no need to "develop" the PCB, just wash off with water!!
> > I may be way off track with this but any comments and/or suggestions?
> > 
> > David
> >
>

Another emulsion base for homebrew resist is Gum Arabic......

http://www.ebay.co.uk/itm/250g-Arabic-gum-powder-food-grade-Acacia-top-grade-/140426888757?pt=Uk_Crafts_Cake_Decorating_MJ&hash=item20b2184635

David

--- In Homebrew_PCBs@yahoogroups.com, "mark" <STRIPES97_USA@...> wrote:

>
> That's a good question as I was thinking about the same thing when I got a screen printing setup a few months ago, but haven't had time to even do more then open the box to make sure everything was in the kit...
> 
> --- In Homebrew_PCBs@yahoogroups.com, "David" <dgh2259@> wrote:
> >
> > Hi All,
> > After looking at Craig's fasinating PCB spinning methods, an idea came to mind, seeing as the regular chemicals seem to be rare and expensive, has anyone tried silk screen printing emulsions? this in not the inks but the chemical used to make the pattern in a very fine mesh, the emulsion is spread over the mesh with a squeegy and after exposure to UV through the pattern[design] blocking transparency, the unexposed area is washed out with running water, the exposed area remains and is really pretty tough, is this resistant to etching chemicals? would this method work? has anyone tried?
> > There would be no need to "develop" the PCB, just wash off with water!!
> > I may be way off track with this but any comments and/or suggestions?
> > 
> > David
> >
>

I don't know if the "bake" operation would really be helpful. The bake 
step was important with the spirit-based polymers like Kodak KPR, etc in 
order to
drive off any volatiles that might be remaining that could damage the 
artwork, which was usually a piece of lithographic photo film.

If the Ulano emulsions can be thinned down to allow spin coating and 
still do good  imaging, then the scheme might work quite well.

If the Ulano emulsion has a spirit base, then perhaps a short term 
mild-temp "bake" might be beneficial.

Someone needs to bite the bullet and purchase some of the Ulano stuff 
and start experimenting.

I find that I'm usually "rolling the dice" when I use the toner transfer 
method in that I'm never quite sure
how good result will be, even though I've tried to standardize my 
technique as much as I can.

Roland F. Harriston, P.D.
********************

David wrote:
>  
>
> I think the general concensus is it will probably work, using the 
> spinning method to achieve a thin uniform layer and baking it for a 
> short while, then expose as normal, one less chemical to use as 
> unexposed resist just washes off, not sure how well the exposed area 
> will stick to the copper clad though, a few experiments should wrap it 
> up though!
>
> Another interesting alternative to the various PCB and Silk Screen 
> chemicals available is to make it yourself!
>
> A mixture of Potassium Dichromate [or bichromate] and Egg yoke, or 
> dairy cream, will make a UV sensitive emulsion.[how this stands up to 
> etching though........] not sure of the mixing ratios, but, it is 
> toxic!! a carcinogenic, and chromium dermatitis are two of the more 
> unpleasant results of getting in contact with the stuff!! it is sold 
> on ebay amongst other places;
>
> http://www.ebay.co.uk/itm/Potassio-bicromato-Kaliumdichromat-potassium-dichromate-/180861035286?pt=Laboratorio_e_Scienze_Mediche&hash=item2a1c286316 
> <http://www.ebay.co.uk/itm/Potassio-bicromato-Kaliumdichromat-potassium-dichromate-/180861035286?pt=Laboratorio_e_Scienze_Mediche&hash=item2a1c286316>
>
> if anyone would like to experiment?..........
>
> David
>
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "mark" <STRIPES97_USA@...> 
> wrote:
> >
> > That's a good question as I was thinking about the same thing when I 
> got a screen printing setup a few months ago, but haven't had time to 
> even do more then open the box to make sure everything was in the kit...
> >
> > --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "David" <dgh2259@> wrote:
> > >
> > > Hi All,
> > > After looking at Craig's fasinating PCB spinning methods, an idea 
> came to mind, seeing as the regular chemicals seem to be rare and 
> expensive, has anyone tried silk screen printing emulsions? this in 
> not the inks but the chemical used to make the pattern in a very fine 
> mesh, the emulsion is spread over the mesh with a squeegy and after 
> exposure to UV through the pattern[design] blocking transparency, the 
> unexposed area is washed out with running water, the exposed area 
> remains and is really pretty tough, is this resistant to etching 
> chemicals? would this method work? has anyone tried?
> > > There would be no need to "develop" the PCB, just wash off with 
> water!!
> > > I may be way off track with this but any comments and/or suggestions?
> > >
> > > David
> > >
> >
>
> 



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

I Gum Arabic photosensitive? And does it polymerize (harden) after being 
exposed to light?

Roland F. Harriston, P.D.
******************

David wrote:
>  
>
> Another emulsion base for homebrew resist is Gum Arabic......
>
>
> >
>
> 



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

Hello,

A couple of years ago, as Vesko, I used homebrew photo resist based on
chemicals used for silk screen printing.
I have had a good results with this process however to achieve this results
you must have some practice and patience.
I have some pictures of boards that I did in the past with this process:
http://tinyurl.com/cj7d5bn

L. Lessa

Em 15 de abril de 2012 16:54, Roland F. Harriston <rolohar@...>escreveu:

> I Gum Arabic photosensitive? And does it polymerize (harden) after being
> exposed to light?
>
> Roland F. Harriston, P.D.
> ******************
>
> David wrote:
> >
> >
> > Another emulsion base for homebrew resist is Gum Arabic......
> >
> >
> > >
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>


-- 

Leonardo Lessa
Linux User #65287


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

Roland,
Sorry, it was an addendum to my previous message, Gum Arabic could be used as the emulsion base, as can egg yoke, cream etc. when mixed with the potassium dichromate, once mixed they will all polymerize after exposure to UV or sunlight, after washing the unexposed areas away it would be a good idea to expose the board to UV again, this will give an extra hardening phase,as one does to polymer plates used in hot foil presses, not sure how these emulsions will stand up to etching chemicals though........

The baking phase i mentioned was to dry the freshly applied emulsion, just to speed up the drying before dust settles on it whilst wet.
 
David

--- In Homebrew_PCBs@yahoogroups.com, "Roland F. Harriston" <rolohar@...> wrote:

>
> I Gum Arabic photosensitive? And does it polymerize (harden) after being 
> exposed to light?
> 
> Roland F. Harriston, P.D.
> ******************
> 
> David wrote:
> >  
> >
> > Another emulsion base for homebrew resist is Gum Arabic......
> >
> >
> > >
> >
> > 
> 
> 
> 
> [Non-text portions of this message have been removed]
>

Thanks for information David. I know nothing about Gum Arabic.

Roland F. Harriston, P.D.
******************

David wrote:

>  
>
> Roland,
> Sorry, it was an addendum to my previous message, Gum Arabic could be 
> used as the emulsion base, as can egg yoke, cream etc. when mixed with 
> the potassium dichromate, once mixed they will all polymerize after 
> exposure to UV or sunlight,
>

Re direct application of silk screen emulsions to a PCB . I don't 
generally expect this to work very well. I previously commented on this. 
Please see:
http://tech.groups.yahoo.com/group/Homebrew_PCBs/message/29416
But, to iterate. Each step used the polar/non-polar property for 
immunity from the films dissolving when stability was desired. For 
instance, if the PCB was to be etched in water based ferric chloride, 
then just about any non-polar solvent based resist worked on the PCB. 
This ranged from silk-screened asphalt ink to sensitized shellac-like 
films, UV cured to provide differential resistance to dissolving in the 
the developing organic (non-polar) solvent. Thus the non-polar resist 
was impervious to the water based etchant. The silk screen used this 
polar/non-polar process in reverse. The emulsion on the screen was polar 
in nature -- polyvinyl alcohol, egg albumin, or some such. Either UV 
cured sensitized emulsions or knife cut films that were then moistened 
and attached to the the screen -- typically wooden frames using 
polyester fabric, as silk had long gone out of use. If extreme precision 
was necessary such as thick film hybrids, then stainless steel fabric on 
aluminum frames was used. But then the organic paint was squeegeed onto 
the PCB and being organic, essentially impervious to the water based 
etchant and as the paint was organic, so also the screen emulsion was 
essentially impervious. In the case of thick film hybrids, the solvent 
based inks were screened onto the ceramic substrates, then fired in a 
kiln or belt furnace. The silk screen emulsions I worked with were as 
described below and sensitized with potassium dichromate. Even the UV 
cured ones, were still soft when wet, just a bit more resistant to 
dissolving as they were "developed." thus they would remain behind while 
the rest of the un-exposed image dissolved away. And as mentioned below, 
the potassium dichromate is also a nasty chemical and presents severe 
disposal problems. Don't put it down the drain either (Chrome is a 
severe carcinogenic--remember the movie "Erin Brockovich.")

The two exceptions I'm aware of were discussed in my previous message.
1)Originally the UV sensitized egg based emulsion used on zinc printing 
plates was developed then dipped in chromic acid (which among other 
things is a also a nasty poison and well avoided) that would harden the 
emulsion. But the real hardener was flame. Just as when you burn food 
onto a skillet, the heat process would bake on the emulsion and I'll 
tell you, it was very, very robust. It took sandpaper to remove it. 
However the amount of heat necessary to bake it would also de-laminate a 
standard PCB, so not exactly a PCB compatible process.
2) The newer dry film resists that develop with water based carbonates 
apparently are totally resistant to dissolving when in acidic solutions 
such as the ferric chloride solutions. (Somebody with actual experience 
with these would have to confirm this for me. I.e., what does the 
developed film feel like in the carbonate solution vs in an acidic 
solution?)
Regards,
Charles Patton

On 4/15/2012 12:26 PM, David wrote:
>
> I think the general concensus is it will probably work, using the 
> spinning method to achieve a thin uniform layer and baking it for a 
> short while, then expose as normal, one less chemical to use as 
> unexposed resist just washes off, not sure how well the exposed area 
> will stick to the copper clad though, a few experiments should wrap it 
> up though!
>
> Another interesting alternative to the various PCB and Silk Screen 
> chemicals available is to make it yourself!
>
> A mixture of Potassium Dichromate [or bichromate] and Egg yoke, or 
> dairy cream, will make a UV sensitive emulsion.[how this stands up to 
> etching though........] not sure of the mixing ratios, but, it is 
> toxic!! a carcinogenic, and chromium dermatitis are two of the more 
> unpleasant results of getting in contact with the stuff!! it is sold 
> on ebay amongst other places;
>
> http://www.ebay.co.uk/itm/Potassio-bicromato-Kaliumdichromat-potassium-dichromate-/180861035286?pt=Laboratorio_e_Scienze_Mediche&hash=item2a1c286316 
> <http://www.ebay.co.uk/itm/Potassio-bicromato-Kaliumdichromat-potassium-dichromate-/180861035286?pt=Laboratorio_e_Scienze_Mediche&hash=item2a1c286316>
>
> if anyone would like to experiment?..........
>
> David
>
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "mark" <STRIPES97_USA@...> 
> wrote:
> >
> > That's a good question as I was thinking about the same thing when I 
> got a screen printing setup a few months ago, but haven't had time to 
> even do more then open the box to make sure everything was in the kit...
> >
> > --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "David" <dgh2259@> wrote:
> > >
> > > Hi All,
> > > After looking at Craig's fasinating PCB spinning methods, an idea 
> came to mind, seeing as the regular chemicals seem to be rare and 
> expensive, has anyone tried silk screen printing emulsions? this in 
> not the inks but the chemical used to make the pattern in a very fine 
> mesh, the emulsion is spread over the mesh with a squeegy and after 
> exposure to UV through the pattern[design] blocking transparency, the 
> unexposed area is washed out with running water, the exposed area 
> remains and is really pretty tough, is this resistant to etching 
> chemicals? would this method work? has anyone tried?
> > > There would be no need to "develop" the PCB, just wash off with 
> water!!
> > > I may be way off track with this but any comments and/or suggestions?
> > >
> > > David
> > >
> >
>
>

Leonardo, can you elaborate on the chemicals you used and the process you
used for applying, developing, and etching?  Did you use a recipe for the
chemicals?

 

Jeff  

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Lessa, Leonardo
Sent: Sunday, April 15, 2012 5:10 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Re: Alternative photoresist chemicals - Idea?

 

  

Hello,

A couple of years ago, as Vesko, I used homebrew photo resist based on
chemicals used for silk screen printing.
I have had a good results with this process however to achieve this results
you must have some practice and patience.
I have some pictures of boards that I did in the past with this process:
http://tinyurl.com/cj7d5bn

L. Lessa

Em 15 de abril de 2012 16:54, Roland F. Harriston <rolohar@...
<mailto:rolohar%40comcast.net> >escreveu:

> I Gum Arabic photosensitive? And does it polymerize (harden) after being
> exposed to light?
>
> Roland F. Harriston, P.D.
> ******************
>
> David wrote:
> >
> >
> > Another emulsion base for homebrew resist is Gum Arabic......
> >
> >
> > >
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and
Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>

-- 

Leonardo Lessa
Linux User #65287

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





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

I did a little research on the silkscreen emulsions by looking at the chemical consultants web site and the MSDS for some of their products.  http://www.ccidom.com/  

Turns out SS emulsions are Diazo activated and come both pre-activated and user activated with the Diazo. ( P-Diaozeoiphenylanin Bisulfate and Paraformaldehyde).  This is sort similar to the stuff used in photo resists if you look at some of the patents.  The difference is in the base material that gets polymerized.  The SS emulsion uses a Vinyl Acetate monomer but the PCB photo resist use a Novolack resin, which is a phenol formaldehyde (Bakelite).

According to Wikipedia the Diazo  inhibits the dissolution of the novolac resin  but after exposure to UV the dissolution rate increases even beyond that of the pure novolack.  It's even more soluble in a mild basic solution (1-2% sodium carbonate solution) after exposure.

The SS emulsions are removed by olain water wash on the exposed areas.  An oxidizer ( Sodium Periodate) solution cam be used to remove the hardened emulsion to reclaim the screen.

The real question is the how does the vinyl acetate hold up to hot etchants and what sort of  resolution can one get.

Would be nice to  DIY  formulate AZ111 , though I suspect that a replacement product is available that would work as well.  The issue is where to get it in small volumes.   Would be nice if one could mix as needed  to eliminate the shelf life issues.

Not done any searching on Novolack. 

Craig.

The best DIY formula for both photoresists and solder mask is contained in this patent,

http://www.google.com/patents/US5556735

See Example 2 for an explicit recipe and an outline of the process together with the necessary exposure in mJ/cm2. I bought all of the ingredients, but couldn't carry it through to a satisfactory emulsion because I lacked a high speed mixing mill to incorporate the polyvinyl acetate.

The thing is, however, that Elmer's School Glue is basically the same polyvinyl acetate/polyvinyl alcohol mixture as in Example 2. It also incorporates some flow aid and surfactants. I experimented with it using both diazo and ammonium dichromate sensitizers with a metal halide exposure unit and it does indeed crosslink very nicely. You need to give a coated board a gentle pre-bake to dry it, then apply the patterned transparency and expose it. I used 800 mJ/cm2. The results were satisfactory. The unexposed areas were removable with a little rubbing under water. I had to move on to other things so this is about as far as I went. With some further experimentation, I do believe that this is a viable homebrew process. I was mostly interested in the solder mask aspects.

Baxter

--- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@...> wrote:
>
> I did a little research on the silkscreen emulsions by looking at the chemical consultants web site and the MSDS for some of their products.  http://www.ccidom.com/

Baxter,
From your description it sounds like this is a negative acting resist in that the exposed parts cross linked and became insoluable.  It makes sense but I am a little confused at the moment because the Shipley AZ111 was a positive resist and used similar chemicals.

I did some more reading today and found this entire area is not unique to PCB making.  There is an entire group of DIY folks trying to do the same thing for producint 4 color gelatin/dye photo prints. They have been looking into photo chemicals that are safer than the chromates.  Also I found that the old Shipley AZ111 is still available but the company is now AZ Electronic Materials and the AZ111 has been reformulated with safer solvents to AS111XFS.  Haven't found a small quantity distributor yet or any pricing.

I would like to know what is in the Genesis AQ3000 neative acting water based stuff I have, it may be PVA based.  Nope I just found the MSDS it is based on Acrylic Polymers and Multifunctional Acrylates and water.
 At one time they had quarts on ebay.  www.genesismt.com 

Wish they had this stuff in 8oz bottles.

Craig

Larry, do you still have dry film resist available?  I would like to contact
you concerning a purchase.  

 

Jeff



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

Hi Jeff,

I did this a long time ago, I need to check my notes.
On the top of my mind, I used a regular water soluble emulsion and sensitizing,
I follow the instructions for mix the emulsion and sensitizing (9:1), for
apply the emulsion on the board and create a thin layer, I used a home
made centrifuge
(Old CD-ROM Motor and a CD). I exposed the board on a 500W halogen lamp and
for developing the board I used water for etching ferric chloride.

Leonardo

Em 15 de abril de 2012 21:47, Jeff Heiss <jeff.heiss@...> escreveu:

> Leonardo, can you elaborate on the chemicals you used and the process you
> used for applying, developing, and etching?  Did you use a recipe for the
> chemicals?
>
>
>
> Jeff
>
>
>
>  _____
>
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> On Behalf Of Lessa, Leonardo
> Sent: Sunday, April 15, 2012 5:10 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Re: Alternative photoresist chemicals - Idea?
>
>
>
>
>
> Hello,
>
> A couple of years ago, as Vesko, I used homebrew photo resist based on
> chemicals used for silk screen printing.
> I have had a good results with this process however to achieve this results
> you must have some practice and patience.
> I have some pictures of boards that I did in the past with this process:
> http://tinyurl.com/cj7d5bn
>
> L. Lessa
>
> Em 15 de abril de 2012 16:54, Roland F. Harriston <rolohar@...
> <mailto:rolohar%40comcast.net> >escreveu:
>
> > I Gum Arabic photosensitive? And does it polymerize (harden) after being
> > exposed to light?
> >
> > Roland F. Harriston, P.D.
> > ******************
> >
> > David wrote:
> > >
> > >
> > > Another emulsion base for homebrew resist is Gum Arabic......
> > >
> > >
> > > >
> > >
> > >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Be sure to visit the group home and check for new Links, Files, and
> Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> >
> >
> >
> >
>
> --
>
> Leonardo Lessa
> Linux User #65287
>
> [Non-text portions of this message have been removed]
>
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>


-- 

Leonardo Lessa
Linux User #65287


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

Homemade resist of potassium dichromate and PVA/gelatin/egg-yoke does not
stand up to HCl and hydrogen peroxide (I tried it).  It seems to work with
moderate results with ferric chloride though.  

 

Can someone try emulsion with ferric chloride and HCL/hydrogen peroxide?
Could 5 mil lines with 5 mil spacing be included?

 

Jeff

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of David
Sent: Sunday, April 15, 2012 3:27 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Alternative photoresist chemicals - Idea?

 

  

I think the general concensus is it will probably work, using the spinning
method to achieve a thin uniform layer and baking it for a short while, then
expose as normal, one less chemical to use as unexposed resist just washes
off, not sure how well the exposed area will stick to the copper clad
though, a few experiments should wrap it up though!

Another interesting alternative to the various PCB and Silk Screen chemicals
available is to make it yourself!

A mixture of Potassium Dichromate [or bichromate] and Egg yoke, or dairy
cream, will make a UV sensitive emulsion.[how this stands up to etching
though........] not sure of the mixing ratios, but, it is toxic!! a
carcinogenic, and chromium dermatitis are two of the more unpleasant results
of getting in contact with the stuff!! it is sold on ebay amongst other
places;

http://www.ebay.co.uk/itm/Potassio-bicromato-Kaliumdichromat-potassium-dichr
omate-/180861035286?pt=Laboratorio_e_Scienze_Mediche
<http://www.ebay.co.uk/itm/Potassio-bicromato-Kaliumdichromat-potassium-dich
romate-/180861035286?pt=Laboratorio_e_Scienze_Mediche&hash=item2a1c286316>
&hash=item2a1c286316

if anyone would like to experiment?..........

David

--- In Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com> , "mark" <STRIPES97_USA@...> wrote:
>
> That's a good question as I was thinking about the same thing when I got a
screen printing setup a few months ago, but haven't had time to even do more
then open the box to make sure everything was in the kit...
> 
> --- In Homebrew_PCBs@yahoogroups.com
<mailto:Homebrew_PCBs%40yahoogroups.com> , "David" <dgh2259@> wrote:
> >
> > Hi All,
> > After looking at Craig's fasinating PCB spinning methods, an idea came
to mind, seeing as the regular chemicals seem to be rare and expensive, has
anyone tried silk screen printing emulsions? this in not the inks but the
chemical used to make the pattern in a very fine mesh, the emulsion is
spread over the mesh with a squeegy and after exposure to UV through the
pattern[design] blocking transparency, the unexposed area is washed out with
running water, the exposed area remains and is really pretty tough, is this
resistant to etching chemicals? would this method work? has anyone tried?
> > There would be no need to "develop" the PCB, just wash off with water!!
> > I may be way off track with this but any comments and/or suggestions?
> > 
> > David
> >
>





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