Homebrew PCBs

Hello,

For SolderMask with Inkjet printer, you can see form Printar 
http://www.all4-pcb.us/printar.htm

The ink for solder mask is appromatevely the same for nomenclature just the color green or white.

But the viscosity is so so so hight, you can turn the pot and the ink not go out, very big marmelade, i think no possibility to put in inkjet cartridje

Special ink for solderMask, is necessacery go to 250� centigrade, for resist solder and automatik solder machine, reflow.

Also, special ink for solder mask by "LACKWERK PETERS"
http://www.peters.de/index_e.htm

ELPEMER photoimageable is a nice system 2467 pack, but in component.
Developement in sodic soap.

For dry film solder mask: CONFORMASK by  SHIPLEY
http://www.pcb-pool.com/download/spezifikation/eng_ConforMask_2500_(englisch).pdf
Developement in sodic soap.

Very nice process, vacum system not necesary for amateur application, just laminate, UV insolation and develop.

For copy film, also from SHIPLEY, "DIAZO-FILM", just copy transparent film from for lazer printed and copy with UV contact  chassi.
Developpement in amonia vapor soap the same from architechture copy plant.

You have a orange transparency film, you can place and see your pad to adjust position film and make UV exposur; very strong film.

Patrick

 

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

Hello everyone.
 It's been a while since I've posted anything, I haven't been making my own boards because of all the chemicals but I keep reading the posts from the group.
 
I saw a post on solder mask and always wondered how it was done, I saw the video linked by a post and today I ran into another one.
 
On this page http://www.lpkfusa.com/boardfinish/promask-view.htm there is a link
http://www.lpkfusa.com/video/promask.wvx to a solder mask windows media video.
 
I wanted to buy one of their machines once but they are too high for my budget.
 


      

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

--- In Homebrew_PCBs@yahoogroups.com, Viper62pr <viper62pr@...> wrote:
>
> Hello everyone.
>  It's been a while since I've posted anything, I haven't been making my own boards because of all the chemicals but I keep reading the posts from the group.
>  
> I saw a post on solder mask and always wondered how it was done, I saw the video linked by a post and today I ran into another one.
>  
> On this page http://www.lpkfusa.com/boardfinish/promask-view.htm there is a link
> http://www.lpkfusa.com/video/promask.wvx to a solder mask windows media video.
>  
> I wanted to buy one of their machines once but they are too high for my budget.
>  


The lpkf machines and supplies are intended for prototyping use. That is why they are overpriced. For "prototyping" I am not meaning "hobby" or small volume stuff. "Prototyping" in the PCB industry means that maybe you want to make thousands of PCBs, but you need a single finished PCB, maybe right now, today or tomorrow, to assembly and test your design before spending money on the thousands of PCBs. However, that 24-hour finished PCB could cost dozens of times much that their normal price, but can save you too much money if you detect or want to change any issue before batch PCB making.

What you should get is real industrial soldermask for large batch making. It is around USD$70/kilogram. 

And by the way, as someone stated, UV Leds are not used for UV curing or imaging of PCB processes. If you want to build a real-use UV photoimaging box, do not waste money on UV leds. Use blacklight fluorescent tubes. They are cheaper, and provide real results. In fact, they are used widely in PCB making (However, for fast batch use, there is no substitute for high power mercury arc lamps).

I'm using a uv film solder mask with great results.
If there is interest I'll post a video.

When you mean a black light fluorescent lamps are the ones that are used into some clubes that makes your theet shine ?... or to see if a bill is original ?... if so what is the power of it ?.

I have 8 tubes of UV lamps of 20W each... does it work right ?.

Who sells that UV solder mask ?... US ?  UK ?

What about the art for the components (white drawings) ?  Is the same procedure ?

Thanks for your help

AFHN




________________________________

From: jcarlosmor <jcarlosmor@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Thursday, September 3, 2009 1:10:14 PM
Subject: [Homebrew_PCBs] Re: Solder Mask

  
--- In Homebrew_PCBs@ yahoogroups. com, Viper62pr <viper62pr@. ..> wrote:
>
> Hello everyone.
>  It's been a while since I've posted anything, I haven't been making my own boards because of all the chemicals but I keep reading the posts from the group.
>  
> I saw a post on solder mask and always wondered how it was done, I saw the video linked by a post and today I ran into another one.
>  
> On this page http://www.lpkfusa. com/boardfinish/ promask-view. htm there is a link
> http://www.lpkfusa. com/video/ promask.wvx to a solder mask windows media video.
>  
> I wanted to buy one of their machines once but they are too high for my budget.
>  

The lpkf machines and supplies are intended for prototyping use. That is why they are overpriced. For "prototyping" I am not meaning "hobby" or small volume stuff. "Prototyping" in the PCB industry means that maybe you want to make thousands of PCBs, but you need a single finished PCB, maybe right now, today or tomorrow, to assembly and test your design before spending money on the thousands of PCBs. However, that 24-hour finished PCB could cost dozens of times much that their normal price, but can save you too much money if you detect or want to change any issue before batch PCB making.

What you should get is real industrial soldermask for large batch making. It is around USD$70/kilogram. 

And by the way, as someone stated, UV Leds are not used for UV curing or imaging of PCB processes. If you want to build a real-use UV photoimaging box, do not waste money on UV leds. Use blacklight fluorescent tubes. They are cheaper, and provide real results. In fact, they are used widely in PCB making (However, for fast batch use, there is no substitute for high power mercury arc lamps).





      

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

--- In Homebrew_PCBs@yahoogroups.com, Andres Hernandez <afhernandez79@...> wrote:
>
> When you mean a black light fluorescent lamps are the ones that are used into some clubes that makes your theet shine ?... or to see if a bill is original ?... if so what is the power of it ?.
> 
> I have 8 tubes of UV lamps of 20W each... does it work right ?.
> 
> Who sells that UV solder mask ?... US ?  UK ?
> 
> What about the art for the components (white drawings) ?  Is the same procedure ?
> 
> Thanks for your help
> 
> AFHN
> 

Yes, some people use UV lighting for entertainment (which is dangerous for the eyes and skin). Although if you ask them, it seems that they do not know about the hazards and they do not do it with a bad intention. They only think that "black light" is for decoration or so.

Never use UV germicidal lamps. Those lamps are transparent glass and are not intended for UV PCB making. Also they are very very dangerous.

The lamps suitable for PCB are the most common and cheap "black light fluorescent tubes" in the market. You can found them in several versions. Avoid the "disco lamp, black light techno" stuff advertised as specialized lamps. They may include some coatings to be very attractive for the eyes in disco fiesta-party, but may affect the wavelenght that is optimal for PCB.

You are reduced then to the BL and BLB types of black lighting. Some models of BLB include a painted "filter", which could be dark blue or even brown ("wood filter"). They may work but then again your PCB may not respond well.

So stick with the BL models. When they are not powered up, they look exactly like a normal white fluorescent light. No coating, no painting, etc. When they are powered up, they emit a dim light-purple-blue tone. However, the radiation of UV is consistent and powerful, so always use a box or container to expose your PCBs.

A common part number is F15T8BL lamps. Some substitutes may be encountered for different manufacturers. Remember, there is nothing special or magic with the lamps in commercial UV imaging systems. They only use the right kind of lamp, which, fortunately, is a very basic, common, and cheap type.

With eight 20-Watt lamps you could build a very decent double sided UV imaging system (four lamps by side).

Well I already have UV germicidal Lamps and I have been careful with those ones and I have seen they work for exposing silk screen applications (the method I have been using for solder mask and white drawings). Are those fine for the meantime ? or I wasted my money ?

I can replace them but not for now.

Thanks




________________________________

From: jcarlosmor <jcarlosmor@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Thursday, September 3, 2009 3:27:56 PM
Subject: [Homebrew_PCBs] Re: Solder Mask

  
--- In Homebrew_PCBs@ yahoogroups. com, Andres Hernandez <afhernandez79@ ...> wrote:
>
> When you mean a black light fluorescent lamps are the ones that are used into some clubes that makes your theet shine ?... or to see if a bill is original ?... if so what is the power of it ?.
> 
> I have 8 tubes of UV lamps of 20W each... does it work right ?.
> 
> Who sells that UV solder mask ?... US ?  UK ?
> 
> What about the art for the components (white drawings) ?  Is the same procedure ?
> 
> Thanks for your help
> 
> AFHN
> 

Yes, some people use UV lighting for entertainment (which is dangerous for the eyes and skin). Although if you ask them, it seems that they do not know about the hazards and they do not do it with a bad intention. They only think that "black light" is for decoration or so.

Never use UV germicidal lamps. Those lamps are transparent glass and are not intended for UV PCB making. Also they are very very dangerous.

The lamps suitable for PCB are the most common and cheap "black light fluorescent tubes" in the market. You can found them in several versions. Avoid the "disco lamp, black light techno" stuff advertised as specialized lamps. They may include some coatings to be very attractive for the eyes in disco fiesta-party, but may affect the wavelenght that is optimal for PCB.

You are reduced then to the BL and BLB types of black lighting. Some models of BLB include a painted "filter", which could be dark blue or even brown ("wood filter"). They may work but then again your PCB may not respond well.

So stick with the BL models. When they are not powered up, they look exactly like a normal white fluorescent light. No coating, no painting, etc. When they are powered up, they emit a dim light-purple- blue tone. However, the radiation of UV is consistent and powerful, so always use a box or container to expose your PCBs.

A common part number is F15T8BL lamps. Some substitutes may be encountered for different manufacturers. Remember, there is nothing special or magic with the lamps in commercial UV imaging systems. They only use the right kind of lamp, which, fortunately, is a very basic, common, and cheap type.

With eight 20-Watt lamps you could build a very decent double sided UV imaging system (four lamps by side).





      

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

Hello again

Please can you tell me what would be the best distance for exposure the Borads ?

Thanks

Atte

AFHN




________________________________

From: jcarlosmor <jcarlosmor@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Thursday, September 3, 2009 3:27:56 PM
Subject: [Homebrew_PCBs] Re: Solder Mask

  
--- In Homebrew_PCBs@ yahoogroups. com, Andres Hernandez <afhernandez79@ ...> wrote:
>
> When you mean a black light fluorescent lamps are the ones that are used into some clubes that makes your theet shine ?... or to see if a bill is original ?... if so what is the power of it ?.
> 
> I have 8 tubes of UV lamps of 20W each... does it work right ?.
> 
> Who sells that UV solder mask ?... US ?  UK ?
> 
> What about the art for the components (white drawings) ?  Is the same procedure ?
> 
> Thanks for your help
> 
> AFHN
> 

Yes, some people use UV lighting for entertainment (which is dangerous for the eyes and skin). Although if you ask them, it seems that they do not know about the hazards and they do not do it with a bad intention. They only think that "black light" is for decoration or so.

Never use UV germicidal lamps. Those lamps are transparent glass and are not intended for UV PCB making. Also they are very very dangerous.

The lamps suitable for PCB are the most common and cheap "black light fluorescent tubes" in the market. You can found them in several versions. Avoid the "disco lamp, black light techno" stuff advertised as specialized lamps. They may include some coatings to be very attractive for the eyes in disco fiesta-party, but may affect the wavelenght that is optimal for PCB.

You are reduced then to the BL and BLB types of black lighting. Some models of BLB include a painted "filter", which could be dark blue or even brown ("wood filter"). They may work but then again your PCB may not respond well.

So stick with the BL models. When they are not powered up, they look exactly like a normal white fluorescent light. No coating, no painting, etc. When they are powered up, they emit a dim light-purple- blue tone. However, the radiation of UV is consistent and powerful, so always use a box or container to expose your PCBs.

A common part number is F15T8BL lamps. Some substitutes may be encountered for different manufacturers. Remember, there is nothing special or magic with the lamps in commercial UV imaging systems. They only use the right kind of lamp, which, fortunately, is a very basic, common, and cheap type.

With eight 20-Watt lamps you could build a very decent double sided UV imaging system (four lamps by side).





      

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

Fred, I'd certianly be interested in seeing your video - I'd LOVE to use some type of solder mask on my boards - sure makes them look nice.

Ken

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

>
> I'm using a uv film solder mask with great results.
> If there is interest I'll post a video.
>

I have this question:

Does this black lights are switable for drifilm laminated too ? what would be the correct distance ?

Thanks for your help




________________________________

From: jcarlosmor <jcarlosmor@...>
To: Homebrew_PCBs@yahoogroups.com
Sent: Thursday, September 3, 2009 3:27:56 PM
Subject: [Homebrew_PCBs] Re: Solder Mask

  
--- In Homebrew_PCBs@ yahoogroups. com, Andres Hernandez <afhernandez79@ ...> wrote:
>
> When you mean a black light fluorescent lamps are the ones that are used into some clubes that makes your theet shine ?... or to see if a bill is original ?... if so what is the power of it ?.
> 
> I have 8 tubes of UV lamps of 20W each... does it work right ?.
> 
> Who sells that UV solder mask ?... US ?  UK ?
> 
> What about the art for the components (white drawings) ?  Is the same procedure ?
> 
> Thanks for your help
> 
> AFHN
> 

Yes, some people use UV lighting for entertainment (which is dangerous for the eyes and skin). Although if you ask them, it seems that they do not know about the hazards and they do not do it with a bad intention. They only think that "black light" is for decoration or so.

Never use UV germicidal lamps. Those lamps are transparent glass and are not intended for UV PCB making. Also they are very very dangerous.

The lamps suitable for PCB are the most common and cheap "black light fluorescent tubes" in the market. You can found them in several versions. Avoid the "disco lamp, black light techno" stuff advertised as specialized lamps. They may include some coatings to be very attractive for the eyes in disco fiesta-party, but may affect the wavelenght that is optimal for PCB.

You are reduced then to the BL and BLB types of black lighting. Some models of BLB include a painted "filter", which could be dark blue or even brown ("wood filter"). They may work but then again your PCB may not respond well.

So stick with the BL models. When they are not powered up, they look exactly like a normal white fluorescent light. No coating, no painting, etc. When they are powered up, they emit a dim light-purple- blue tone. However, the radiation of UV is consistent and powerful, so always use a box or container to expose your PCBs.

A common part number is F15T8BL lamps. Some substitutes may be encountered for different manufacturers. Remember, there is nothing special or magic with the lamps in commercial UV imaging systems. They only use the right kind of lamp, which, fortunately, is a very basic, common, and cheap type.

With eight 20-Watt lamps you could build a very decent double sided UV imaging system (four lamps by side).





      

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

-----Original Message-----
Date: Thursday, September 03, 2009 9:20 am
To: Homebrew_PCBs@yahoogroups.com

Subject: [Homebrew_PCBs] Solder Mask
From: "Viper62pr" <viper62pr@...>

Hello everyone.
\ufffdIt's been a while since I've posted anything, I haven't been making my own boards because of all the chemicals but I keep reading the posts from the group.
\ufffd
I saw a post on solder mask and always wondered how it was done, I saw the video linked by a post and today I ran into another one.
\ufffd
On this page http://www.lpkfusa.com/boardfinish/promask-view.htm\ufffdthere is a link
http://www.lpkfusa.com/video/promask.wvx\ufffdto a solder mask windows media video.
\ufffd
I wanted to buy one of their machines once but they are too high for my budget.
\ufffd


      

[Non-text portions of this message have been removed]
i too lurk here - i do slaughtermask at a big pcb shop - lpi is the ticket

jcarlosmor wrote:
>  

> And by the way, as someone stated, UV Leds are not used for UV curing or 
> imaging of PCB processes. If you want to build a real-use UV 
> photoimaging box, do not waste money on UV leds. Use blacklight 
> fluorescent tubes. They are cheaper, and provide real results. In fact, 
> they are used widely in PCB making (However, for fast batch use, there 
> is no substitute for high power mercury arc lamps).
> 

After experience with both 395nm UV LED and BL tube (spectral peak 
365nm) light sources, I would totally agree. The major problem with LEDs 
is light non-uniformity and inadequate intensity for solder mask and 
positive resists. Only the negative dry film photoresists seem to be 
sensitive enough. For some reason, extending the exposure time with LEDs 
does not work on these materials.

One would expect excessive light undercut from the relatively wide angle 
radiation pattern emitted by an array of BL tubes. In my experience, 
0.2mm (0.008") line/spaces are easily achievable. It is critical the ink 
side of transparency makes contact with the photoresist. I found the 
ratio of maximum/minimum exposure time can be high as 1.5 while still 
maintaining an acceptable deviation in line & space widths.

The limit to minimum line & space is not the exposure source, but that 
of inkjet printer resolution.

Adam

--- In Homebrew_PCBs@yahoogroups.com, Andres Hernandez <afhernandez79@...> wrote:
>
> I have this question:
> 
> Does this black lights are switable for drifilm laminated too ? what would be the correct distance ?
> 

What model specifically do you mean?

You could get very good results with the lamps about 5 centimeters from the PCB. There are considerations about parallelism of the light emitted when it is too close, but commercial units are built that way and work okay for most work. You could study and build a collimer for the light using different methods but I suggest that you try first with the proper lamps and see for yourself the results. You won't be dissapointed.

My results are different. I have built two exposure systems and use boards that are laminated with photo resist by a PC shop in Jamestown,NC. With the 24 inch bulbs from Japan made with optimized dopants for UV, my exposure time at about 4 inches is about 50 seconds. This system required 4 lamps and 4 ballasts which were expensive but work very well. Total cost was around $90. The UV lamps off e-bay cost around $18 for 150 pieces. I made up a board  6X6 and made an array of 10X10 and current regulated each 10 piece row for an additional $2 with SMT devices. I get similar exposures at 6 inches and use much less power, get instant and RELIABLE turn-ons and prefer it for sure. I will provide boards and schematic for $12 if interested.Will include regulator components also.
 
Ed Smith  W4EDS
Spencer, VA
w4eds@yahoo.com
 
===============================================================

--- On Sat, 9/5/09, Adam Seychell <a_seychell@...> wrote:

From: Adam Seychell <a_seychell@...>
Subject: [Homebrew_PCBs] exposure sources (was: Solder Mask)
To: Homebrew_PCBs@yahoogroups.com
Date: Saturday, September 5, 2009, 3:35 AM


  



jcarlosmor wrote:
> 

> And by the way, as someone stated, UV Leds are not used for UV curing or 
> imaging of PCB processes. If you want to build a real-use UV 
> photoimaging box, do not waste money on UV leds. Use blacklight 
> fluorescent tubes. They are cheaper, and provide real results. In fact, 
> they are used widely in PCB making (However, for fast batch use, there 
> is no substitute for high power mercury arc lamps).
> 

After experience with both 395nm UV LED and BL tube (spectral peak 
365nm) light sources, I would totally agree. The major problem with LEDs 
is light non-uniformity and inadequate intensity for solder mask and 
positive resists. Only the negative dry film photoresists seem to be 
sensitive enough. For some reason, extending the exposure time with LEDs 
does not work on these materials.

One would expect excessive light undercut from the relatively wide angle 
radiation pattern emitted by an array of BL tubes. In my experience, 
0.2mm (0.008") line/spaces are easily achievable. It is critical the ink 
side of transparency makes contact with the photoresist. I found the 
ratio of maximum/minimum exposure time can be high as 1.5 while still 
maintaining an acceptable deviation in line & space widths.

The limit to minimum line & space is not the exposure source, but that 
of inkjet printer resolution.

Adam
















      

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

--- In Homebrew_PCBs@yahoogroups.com, "sailingto" <sailingto@...> wrote:
>
> Fred, I'd certianly be interested in seeing your video - I'd LOVE to use some type of solder mask on my boards - sure makes them look nice.
> 
> Ken
> 
> --- In Homebrew_PCBs@yahoogroups.com, "fredbutz" <fredbutz@> wrote:
> >
> > I'm using a uv film solder mask with great results.
> > If there is interest I'll post a video.
> >
>

Sorry, I got tied up with a weekend programming a database to track all these electronic components.  I'll get to it soon.
Chuck

I bought a used UV Exposure unit off EBay for $75.
Its pretty big, but works excellent.
I think it was for exposing printer plates.


--- In Homebrew_PCBs@yahoogroups.com, Adam Seychell <a_seychell@...> wrote:

>
> jcarlosmor wrote:
> >  
> 
> > And by the way, as someone stated, UV Leds are not used for UV curing or 
> > imaging of PCB processes. If you want to build a real-use UV 
> > photoimaging box, do not waste money on UV leds. Use blacklight 
> > fluorescent tubes. They are cheaper, and provide real results. In fact, 
> > they are used widely in PCB making (However, for fast batch use, there 
> > is no substitute for high power mercury arc lamps).
> > 
> 
> After experience with both 395nm UV LED and BL tube (spectral peak 
> 365nm) light sources, I would totally agree. The major problem with LEDs 
> is light non-uniformity and inadequate intensity for solder mask and 
> positive resists. Only the negative dry film photoresists seem to be 
> sensitive enough. For some reason, extending the exposure time with LEDs 
> does not work on these materials.
> 
> One would expect excessive light undercut from the relatively wide angle 
> radiation pattern emitted by an array of BL tubes. In my experience, 
> 0.2mm (0.008") line/spaces are easily achievable. It is critical the ink 
> side of transparency makes contact with the photoresist. I found the 
> ratio of maximum/minimum exposure time can be high as 1.5 while still 
> maintaining an acceptable deviation in line & space widths.
> 
> The limit to minimum line & space is not the exposure source, but that 
> of inkjet printer resolution.
> 
> Adam
>

I've been playing with some UV curable green solder mask (Mechanic Brand from China eBay - comes in a 10ml syringe for £1-2).

I get a really even coating by applying it through a silk screen mesh.

You're supposed to lay the artwork over the top and expose it. Then wash away the non-cured parts with solvent. This doesn't work because it is impossible to lay the artwork over the mask without getting bubbles / large voids; if you try lifting the artwork to try again it instantly wrecks the nice even layer. To add insult to injury, if you do get it right then the mask sticks to the artwork like cement after curing.

I tried an intermediate layer of florists cellophane over the mask; this again is virtually impossible to apply without bubbles but it separates easily after curing.

I'd give up because it takes such a lot of faffing except for the fact that when I get a large bubble free area the mask looks really good and it's possible to incorporate legend with the track mask which can be scrubbed over with a chinagraph pencil to look like a real silk screen.

Any thoughts/techniques please?

Bob

storan4wd wrote:
> I've been playing with some UV curable green solder mask (Mechanic Brand from China eBay - comes in a 10ml syringe for \ufffd1-2).
>
> I get a really even coating by applying it through a silk screen mesh.
>
> You're supposed to lay the artwork over the top and expose it. Then wash away the non-cured parts with solvent. This doesn't work because it is impossible to lay the artwork over the mask without getting bubbles / large voids; if you try lifting the artwork to try again it instantly wrecks the nice even layer. To add insult to injury, if you do get it right then the mask sticks to the artwork like cement after curing.
>
> I tried an intermediate layer of florists cellophane over the mask; this again is virtually impossible to apply without bubbles but it separates easily after curing.
>
> I'd give up because it takes such a lot of faffing except for the fact that when I get a large bubble free area the mask looks really good and it's possible to incorporate legend with the track mask which can be scrubbed over with a chinagraph pencil to look like a real silk screen.
>
> Any thoughts/techniques please?
>
> Bob
>   
As long as you are applying it with a silkscreen, why not block out the 
parts where you don't want masking?

Kerry

--- In Homebrew_PCBs@yahoogroups.com, Kerry Wentworth <kwentworth@...> wrote:
>
> storan4wd wrote:
> > I've been playing with some UV curable green solder mask (Mechanic Brand from China eBay - comes in a 10ml syringe for £1-2).
> >
> > I get a really even coating by applying it through a silk screen mesh.
> >
> > You're supposed to lay the artwork over the top and expose it. Then wash away the non-cured parts with solvent. This doesn't work because it is impossible to lay the artwork over the mask without getting bubbles / large voids; if you try lifting the artwork to try again it instantly wrecks the nice even layer. To add insult to injury, if you do get it right then the mask sticks to the artwork like cement after curing.
> >
> > I tried an intermediate layer of florists cellophane over the mask; this again is virtually impossible to apply without bubbles but it separates easily after curing.
> >
> > I'd give up because it takes such a lot of faffing except for the fact that when I get a large bubble free area the mask looks really good and it's possible to incorporate legend with the track mask which can be scrubbed over with a chinagraph pencil to look like a real silk screen.
> >
> > Any thoughts/techniques please?
> >
> > Bob
> >   
> As long as you are applying it with a silkscreen, why not block out the 
> parts where you don't want masking?
> 
> Kerry
>
Hi Kerry,
I use a silk screen mesh but there's no image on it - it's only to ensure and even coating.
Bob

storan4wd wrote:
> --- In Homebrew_PCBs@yahoogroups.com, Kerry Wentworth <kwentworth@...> wrote:
>   
>> storan4wd wrote:
>>     
>>> I've been playing with some UV curable green solder mask (Mechanic Brand from China eBay - comes in a 10ml syringe for \ufffd1-2).
>>>
>>> I get a really even coating by applying it through a silk screen mesh.
>>>
>>> You're supposed to lay the artwork over the top and expose it. Then wash away the non-cured parts with solvent. This doesn't work because it is impossible to lay the artwork over the mask without getting bubbles / large voids; if you try lifting the artwork to try again it instantly wrecks the nice even layer. To add insult to injury, if you do get it right then the mask sticks to the artwork like cement after curing.
>>>
>>> I tried an intermediate layer of florists cellophane over the mask; this again is virtually impossible to apply without bubbles but it separates easily after curing.
>>>
>>> I'd give up because it takes such a lot of faffing except for the fact that when I get a large bubble free area the mask looks really good and it's possible to incorporate legend with the track mask which can be scrubbed over with a chinagraph pencil to look like a real silk screen.
>>>
>>> Any thoughts/techniques please?
>>>
>>> Bob
>>>   
>>>       
>> As long as you are applying it with a silkscreen, why not block out the 
>> parts where you don't want masking?
>>
>> Kerry
>>
>>     
> Hi Kerry,
> I use a silk screen mesh but there's no image on it - it's only to ensure and even coating.
> Bob
>   
But you COULD put an image on it, and have the soldermask only placed 
where you want it.  Then just expose the whole board.  Wouldn't that be 
easier?

Kerry

> But you COULD put an image on it, and have the soldermask only placed 
> where you want it.  Then just expose the whole board.  Wouldn't that be 
> easier?
> 
> Kerry
>
You're right, that would certainly be possible but it's another time consuming procedure to make the screen and it uses limited shelf life chemistry. I have tried it for component legends but with only limited success (I found it very difficult coating the mesh evenly and at the right thickness).

Bob

Bob,

Do I understand correctly that this process does not include a drying step? With other processes I believe you apply the liquid, dry it in an oven, and then expose it with the artwork. It sounds like the problem you are having is dealing with the wet liquid. Wonder what would happen if you let it dry first? Would it still develop under the UV?

--- In Homebrew_PCBs@yahoogroups.com, "storan4wd" <bob.balderson@...> wrote:

>
> 
> > But you COULD put an image on it, and have the soldermask only placed 
> > where you want it.  Then just expose the whole board.  Wouldn't that be 
> > easier?
> > 
> > Kerry
> >
> You're right, that would certainly be possible but it's another time consuming procedure to make the screen and it uses limited shelf life chemistry. I have tried it for component legends but with only limited success (I found it very difficult coating the mesh evenly and at the right thickness).
> 
> Bob
>

I agree with Andrew...all the stuff I have seen, and used, have had an oven drying step before UV curing.

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

>
> Bob,
> 
> Do I understand correctly that this process does not include a drying step? With other processes I believe you apply the liquid, dry it in an oven, and then expose it with the artwork. It sounds like the problem you are having is dealing with the wet liquid. Wonder what would happen if you let it dry first? Would it still develop under the UV?
> 
> --- In Homebrew_PCBs@yahoogroups.com, "storan4wd" <bob.balderson@> wrote:
> >
> > 
> > > But you COULD put an image on it, and have the soldermask only placed 
> > > where you want it.  Then just expose the whole board.  Wouldn't that be 
> > > easier?
> > > 
> > > Kerry
> > >
> > You're right, that would certainly be possible but it's another time consuming procedure to make the screen and it uses limited shelf life chemistry. I have tried it for component legends but with only limited success (I found it very difficult coating the mesh evenly and at the right thickness).
> > 
> > Bob
> >
>

+1, try 70-75 celcius for 20 minutes, then expose, develop, wash and final cure at 120-150 celcius for 40-60 minutes. most uv mask works this way

--- In Homebrew_PCBs@yahoogroups.com, "Terry" <twgray2007@...> wrote:

>
> I agree with Andrew...all the stuff I have seen, and used, have had an oven drying step before UV curing.
> 
> --- In Homebrew_PCBs@yahoogroups.com, "Andrew" <a_wake@> wrote:
> >
> > Bob,
> > 
> > Do I understand correctly that this process does not include a drying step? With other processes I believe you apply the liquid, dry it in an oven, and then expose it with the artwork. It sounds like the problem you are having is dealing with the wet liquid. Wonder what would happen if you let it dry first? Would it still develop under the UV?
> > 
> > --- In Homebrew_PCBs@yahoogroups.com, "storan4wd" <bob.balderson@> wrote:
> > >
> > > 
> > > > But you COULD put an image on it, and have the soldermask only placed 
> > > > where you want it.  Then just expose the whole board.  Wouldn't that be 
> > > > easier?
> > > > 
> > > > Kerry
> > > >
> > > You're right, that would certainly be possible but it's another time consuming procedure to make the screen and it uses limited shelf life chemistry. I have tried it for component legends but with only limited success (I found it very difficult coating the mesh evenly and at the right thickness).
> > > 
> > > Bob
> > >
> >
>

> Do I understand correctly that this process does not include a drying step? With other processes I believe you apply the liquid, dry it in an oven, and then expose it with the artwork. It sounds like the problem you are having is dealing with the wet liquid. Wonder what would happen if you let it dry first? Would it still develop under the UV?

Hi Andrew,

That's exactly right, there is no drying step. I've tried leaving it to air dry and cooking it up a bit in the toaster oven but it just stays runny until it gets some UV.

So why not leave it in the sun for a few minutes to thicken up I hear you ask. Well I may just try that, however it doesn't seem to cure evenly - some areas will go rock solid before others and if you get it wrong you've trashed the pcb as it's impossible to remove once cured.

Regards,

Bob

Thank you psykhon (and Terry and Andrew)!

With all of you saying the same thing I had another shot at drying before curing.

I tried 100C (my oven won't go lower) for 10/20/30mins but the mask was still not touch dry so I left it to cool overnight.

After 10 hours it was just about usable but still not totally dry. It exposed well but I couldn't put much contact pressure on for fear of the artwork sticking so some 5mil test lines were blurred. At any rate, progress has been made.

I think the real lesson I've learned is that the mask is designed for stencil printing only; quick drying isn't a priority as it's not intended to have anything in contact with it when curing. If only I was adept at making silk screen stencils!

Regards,

Bob

--- In Homebrew_PCBs@yahoogroups.com, psykhon@... wrote:

>
> +1, try 70-75 celcius for 20 minutes, then expose, develop, wash and final cure at 120-150 celcius for 40-60 minutes. most uv mask works this way
> 
> --- In Homebrew_PCBs@yahoogroups.com, "Terry" <twgray2007@> wrote:
> >
> > I agree with Andrew...all the stuff I have seen, and used, have had an oven drying step before UV curing.
> > 
> > --- In Homebrew_PCBs@yahoogroups.com, "Andrew" <a_wake@> wrote:
> > >
> > > Bob,
> > > 
> > > Do I understand correctly that this process does not include a drying step? With other processes I believe you apply the liquid, dry it in an oven, and then expose it with the artwork. It sounds like the problem you are having is dealing with the wet liquid. Wonder what would happen if you let it dry first? Would it still develop under the UV?
> > > 
> > > --- In Homebrew_PCBs@yahoogroups.com, "storan4wd" <bob.balderson@> wrote:
> > > >
> > > > 
> > > > > But you COULD put an image on it, and have the soldermask only placed 
> > > > > where you want it.  Then just expose the whole board.  Wouldn't that be 
> > > > > easier?
> > > > > 
> > > > > Kerry
> > > > >
> > > > You're right, that would certainly be possible but it's another time consuming procedure to make the screen and it uses limited shelf life chemistry. I have tried it for component legends but with only limited success (I found it very difficult coating the mesh evenly and at the right thickness).
> > > > 
> > > > Bob
> > > >
> > >
> >
>

storan4wd wrote:
> 
> I think the real lesson I've learned is that the mask is designed for
> stencil printing only; quick drying isn't a priority as it's not
> intended to have anything in contact with it when curing. 

As a side note, did you ever consider that such cheap eBay stuff, sold
from china, is not even similar to real soldermask?

It must be repackaged stuff, the eBay seller can say what he wants with
his package. I don't know to read chinese, but to see what it really is
you could try google goggles from a camera phone and translate, if you
have the real manufacture package. EBay sellers say it's uv curing ink,
but it can just be UV curing EPOXY GLUE.

But if you look to one more expensive seller (the one who started to
sell the stuff as soldermask) he has a working method, see item
260937497342. He lays a bit of it at pcb center and spread it with the
mask directly. Expose for some time and them it should require extra
curing after solvent washing. A couple of years ago i asked him a msds
or that he just say what could be used as thinner for it. His answer:
'this is just chinese crap, no msds/documentation was ever written'.

You should know that real LPI soldermask is half the money by quantity
compared to that stuff. 

BTW (and off topic) Does anyone *really* know what PM or PMA solvent
is???? I must know (and be sure) to use with real soldermask... :/

True that it is a bit expensive on a per ounce basis, but with the volumes necessary for purchase for the 'real stuff' it is not bad...and this is one of the best means of applying soldermask to a homebrew board that I have found.  I've tried every method that I could think of, or find on Google, and never came up with anything that gave results even close to this.  I even went so far at to buy the 'real stuff', which was epoxy based, had to be mixed prior to use, had a very short (1 week) shelf life after mixing, and required a minumum purchase of a 5 gallon bucket of developer.  Total cost about $250.  The stuff from China was about $6.00 - $7.00 per tube, had a long shelf life, and I could make several boards with a single tube.  

Does anyone have a better solution?

--- In Homebrew_PCBs@yahoogroups.com, Simao Cardoso <simaocardoso@...> wrote:

>
> storan4wd wrote:
> > 
> > I think the real lesson I've learned is that the mask is designed for
> > stencil printing only; quick drying isn't a priority as it's not
> > intended to have anything in contact with it when curing. 
> 
> As a side note, did you ever consider that such cheap eBay stuff, sold
> from china, is not even similar to real soldermask?
> 
> It must be repackaged stuff, the eBay seller can say what he wants with
> his package. I don't know to read chinese, but to see what it really is
> you could try google goggles from a camera phone and translate, if you
> have the real manufacture package. EBay sellers say it's uv curing ink,
> but it can just be UV curing EPOXY GLUE.
> 
> But if you look to one more expensive seller (the one who started to
> sell the stuff as soldermask) he has a working method, see item
> 260937497342. He lays a bit of it at pcb center and spread it with the
> mask directly. Expose for some time and them it should require extra
> curing after solvent washing. A couple of years ago i asked him a msds
> or that he just say what could be used as thinner for it. His answer:
> 'this is just chinese crap, no msds/documentation was ever written'.
> 
> You should know that real LPI soldermask is half the money by quantity
> compared to that stuff. 
> 
> BTW (and off topic) Does anyone *really* know what PM or PMA solvent
> is???? I must know (and be sure) to use with real soldermask... :/
>

Terry wrote:

> and required a minumum purchase of a 5 gallon bucket of developer.
> Total cost about $250. 

I know LPI soldermask said to be the world most used, and sold for nine
times less than that, minimum order quantity 1Kg, alkaline carbonate
developer like dry film. 
But i still need to know for sure what is known in English as PMA
solvent...

Hi Simon,

Thanks for that eBay reference - I hadn't seen that particular seller; it's a lot more expensive but it looks very similar to the Mechanic brand that I've got. I realise that you generally get what you pay for but I  have some other cheap Mechanic brand items - solder paste for one which is really excellent.

Regards,

Bob

--- In Homebrew_PCBs@yahoogroups.com, Simao Cardoso <simaocardoso@...> wrote:

>
> storan4wd wrote:
> > 
> > I think the real lesson I've learned is that the mask is designed for
> > stencil printing only; quick drying isn't a priority as it's not
> > intended to have anything in contact with it when curing. 
> 
> As a side note, did you ever consider that such cheap eBay stuff, sold
> from china, is not even similar to real soldermask?
> 
> It must be repackaged stuff, the eBay seller can say what he wants with
> his package. I don't know to read chinese, but to see what it really is
> you could try google goggles from a camera phone and translate, if you
> have the real manufacture package. EBay sellers say it's uv curing ink,
> but it can just be UV curing EPOXY GLUE.
> 
> But if you look to one more expensive seller (the one who started to
> sell the stuff as soldermask) he has a working method, see item
> 260937497342. He lays a bit of it at pcb center and spread it with the
> mask directly. Expose for some time and them it should require extra
> curing after solvent washing. A couple of years ago i asked him a msds
> or that he just say what could be used as thinner for it. His answer:
> 'this is just chinese crap, no msds/documentation was ever written'.
> 
> You should know that real LPI soldermask is half the money by quantity
> compared to that stuff. 
> 
> BTW (and off topic) Does anyone *really* know what PM or PMA solvent
> is???? I must know (and be sure) to use with real soldermask... :/
>

Hi Terry,

I have just ordered a metre of Dynamask
<http://www.octamex.de/shop/?page=shop/flypage&product_id=31&category_id\
=5848924494118370762daa6f026e22f7&/Dynamask__Loetstopplaminat_1m_kaufen.\
html>   to play with. It's certainly not as cheap as green goop but if
it means less faffing time and more repeatable results it will be a
better solution for me. Stay tuned!

Regards,

Bob

--- In Homebrew_PCBs@yahoogroups.com, "Terry" <twgray2007@...> wrote:
>
> True that it is a bit expensive on a per ounce basis, but with the
volumes necessary for purchase for the 'real stuff' it is not bad...and
this is one of the best means of applying soldermask to a homebrew board
that I have found.  I've tried every method that I could think of, or
find on Google, and never came up with anything that gave results even
close to this.  I even went so far at to buy the 'real stuff', which was
epoxy based, had to be mixed prior to use, had a very short (1 week)
shelf life after mixing, and required a minumum purchase of a 5 gallon
bucket of developer.  Total cost about $250.  The stuff from China was
about $6.00 - $7.00 per tube, had a long shelf life, and I could make
several boards with a single tube.
>
> Does anyone have a better solution?
>
> --- In Homebrew_PCBs@yahoogroups.com, Simao Cardoso <simaocardoso@>
wrote:
> >
> > storan4wd wrote:
> > >
> > > I think the real lesson I've learned is that the mask is designed
for
> > > stencil printing only; quick drying isn't a priority as it's not
> > > intended to have anything in contact with it when curing.
> >
> > As a side note, did you ever consider that such cheap eBay stuff,
sold
> > from china, is not even similar to real soldermask?
> >
> > It must be repackaged stuff, the eBay seller can say what he wants
with
> > his package. I don't know to read chinese, but to see what it really
is
> > you could try google goggles from a camera phone and translate, if
you
> > have the real manufacture package. EBay sellers say it's uv curing
ink,
> > but it can just be UV curing EPOXY GLUE.
> >
> > But if you look to one more expensive seller (the one who started to
> > sell the stuff as soldermask) he has a working method, see item
> > 260937497342. He lays a bit of it at pcb center and spread it with
the
> > mask directly. Expose for some time and them it should require extra
> > curing after solvent washing. A couple of years ago i asked him a
msds
> > or that he just say what could be used as thinner for it. His
answer:
> > 'this is just chinese crap, no msds/documentation was ever written'.
> >
> > You should know that real LPI soldermask is half the money by
quantity
> > compared to that stuff.
> >
> > BTW (and off topic) Does anyone *really* know what PM or PMA solvent
> > is???? I must know (and be sure) to use with real soldermask... :/
> >
>

--- In Homebrew_PCBs@yahoogroups.com, "Terry" <twgray2007@...> wrote:
>
> True that it is a bit expensive on a per ounce basis, but with the
volumes necessary for purchase for the 'real stuff' it is not bad...and
this is one of the best means of applying soldermask to a homebrew board
that I have found.  I've tried every method that I could think of, or
find on Google, and never came up with anything that gave results even
close to this.  I even went so far at to buy the 'real stuff', which was
epoxy based, had to be mixed prior to use, had a very short (1 week)
shelf life after mixing, and required a minumum purchase of a 5 gallon
bucket of developer.  Total cost about $250.  The stuff from China was
about $6.00 - $7.00 per tube, had a long shelf life, and I could make
several boards with a single tube.
>
> Does anyone have a better solution?
>
> --- In Homebrew_PCBs@yahoogroups.com, Simao Cardoso simaocardoso@
wrote:
> >
> > storan4wd wrote:
> > >
> > > I think the real lesson I've learned is that the mask is designed
for
> > > stencil printing only; quick drying isn't a priority as it's not
> > > intended to have anything in contact with it when curing.
> >
> > As a side note, did you ever consider that such cheap eBay stuff,
sold
> > from china, is not even similar to real soldermask?
> >
> > It must be repackaged stuff, the eBay seller can say what he wants
with
> > his package. I don't know to read chinese, but to see what it really
is
> > you could try google goggles from a camera phone and translate, if
you
> > have the real manufacture package. EBay sellers say it's uv curing
ink,
> > but it can just be UV curing EPOXY GLUE.
> >
> > But if you look to one more expensive seller (the one who started to
> > sell the stuff as soldermask) he has a working method, see item
> > 260937497342. He lays a bit of it at pcb center and spread it with
the
> > mask directly. Expose for some time and them it should require extra
> > curing after solvent washing. A couple of years ago i asked him a
msds
> > or that he just say what could be used as thinner for it. His
answer:
> > 'this is just chinese crap, no msds/documentation was ever written'.
> >
> > You should know that real LPI soldermask is half the money by
quantity
> > compared to that stuff.
> >
> > BTW (and off topic) Does anyone *really* know what PM or PMA solvent
> > is???? I must know (and be sure) to use with real soldermask... :/
> >
>



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

On a side note, if you have a KitchenAid or similar oven with electronic
control, look under the options menu for a "Dehydrate" mode - that should
allow you to set temperatures lower than 100C

Andrew Hakman

On Mon, Feb 20, 2012 at 6:45 AM, storan4wd <bob.balderson@...>wrote:

> **
>
>
> Thank you psykhon (and Terry and Andrew)!
>
> With all of you saying the same thing I had another shot at drying before
> curing.
>
> I tried 100C (my oven won't go lower) for 10/20/30mins but the mask was
> still not touch dry so I left it to cool overnight.
>
> After 10 hours it was just about usable but still not totally dry. It
> exposed well but I couldn't put much contact pressure on for fear of the
> artwork sticking so some 5mil test lines were blurred. At any rate,
> progress has been made.
>
> I think the real lesson I've learned is that the mask is designed for
> stencil printing only; quick drying isn't a priority as it's not intended
> to have anything in contact with it when curing. If only I was adept at
> making silk screen stencils!
>
> Regards,
>
> Bob
>
> --- In Homebrew_PCBs@yahoogroups.com, psykhon@... wrote:
> >
> > +1, try 70-75 celcius for 20 minutes, then expose, develop, wash and
> final cure at 120-150 celcius for 40-60 minutes. most uv mask works this way
> >
> > --- In Homebrew_PCBs@yahoogroups.com, "Terry" <twgray2007@> wrote:
> > >
> > > I agree with Andrew...all the stuff I have seen, and used, have had an
> oven drying step before UV curing.
> > >
> > > --- In Homebrew_PCBs@yahoogroups.com, "Andrew" <a_wake@> wrote:
> > > >
> > > > Bob,
> > > >
> > > > Do I understand correctly that this process does not include a
> drying step? With other processes I believe you apply the liquid, dry it in
> an oven, and then expose it with the artwork. It sounds like the problem
> you are having is dealing with the wet liquid. Wonder what would happen if
> you let it dry first? Would it still develop under the UV?
> > > >
> > > > --- In Homebrew_PCBs@yahoogroups.com, "storan4wd" <bob.balderson@>
> wrote:
> > > > >
> > > > >
> > > > > > But you COULD put an image on it, and have the soldermask only
> placed
> > > > > > where you want it. Then just expose the whole board. Wouldn't
> that be
> > > > > > easier?
> > > > > >
> > > > > > Kerry
> > > > > >
> > > > > You're right, that would certainly be possible but it's another
> time consuming procedure to make the screen and it uses limited shelf life
> chemistry. I have tried it for component legends but with only limited
> success (I found it very difficult coating the mesh evenly and at the right
> thickness).
> > > > >
> > > > > Bob
> > > > >
> > > >
> > >
> >
>
>  
>


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