The main problem I see is exposing the centre area of the spiral. You
would need to align the disk axis so aligns within 50um of linear axis
of the laser. I'm sure exposure intensity can easily be compensated in
software for constant disk RPM.

Adam

Leslie Newell wrote:
>
>
> The tricky bit is keeping the exposure times reasonably equal. The disk
> would have to speed up as the laser approaches the center line. Nice
> idea though...
>
> Les
>
> javaguy11111 wrote:
>  >
>  > --- In Homebrew_PCBs@ yahoogroups. com
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "designer_craig" <cs6061@...>
> wrote:
>  >> I looked into a couple of these but I believe they are for island
> milling. Converting the xy moves from the gerber to the G-code is the
> easy part the files are almost exactly the same syntax.
>  >>
>  >
>  > I wonder if instead of trying to do cartesian scans, put the board on
> some sort of a spinning disk and run the laser in a radial direction or
> a polar scan. Basically what is done on a DVD writer. You could keep the
> .001 spot size and just spiral in.
>  > That way you are not wasting time with a bunch of stop and start
> motion. May be easier to construct as well.
>
>

Good idea. How to make reliable electrical power  and video connection to the
laser?

--- On Fri, 11/13/09, Adam Seychell <a_seychell@...> wrote:

From: Adam Seychell <a_seychell@...>
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: Homebrew_PCBs@yahoogroups.com
Date: Friday, November 13, 2009, 12:47 PM







 









       Volkan Sahin wrote:

>



> I added laser to the side of inkjet head and I'm using raster scanning

> method to expose photoresist.

> I've the same idea to use polygon mirrors of a old laser printer. I've

> one Brother printer which has an aluminum mirror (most of them have a

> copper or gold plated mirror on  aluminum because of IR laser) and

> plastic lenses it seems it is possible to use with blue laser. I did

> some rough measurements and I saw that on optical path I'm loosing ~30%

> of the power most of it is because of diagonal mirrors because of that I

> left it for a future project.

>



The polygon mirror concept sounds more difficult to implement.

How about a large diameter disc with a laser diode mounted on the

perimeter. The PCB moves linear to the disc. Software would compensate

for uniform exposure energy.



Assume that:



Resolution = 0.005cm (50um)

Disc diameter  = 15cm

Energy 	 = 60mj/cm^2

Laser power  = 85mW



Then



maximum disc RPM

	 = 60 * 1cm/0.005cm / (60/85 * 15*1)

	 = 1133



1000 RPM sounds reasonable.

























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

That's a great idea.  For small boards possilby a CD drive hack would do. Would
take some code to convert the cartesian data to polar data.

One could possible mount several diodes on the radial lead screw to write
multiple sections at once to speed up the process.

Another one I though of a while back was to use something like a DLP projector
with a UV source. But that gets complex.

Craig

--- In Homebrew_PCBs@yahoogroups.com, "javaguy11111" <javaguy11111@...> wrote:
>
>
>
> --- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@> wrote:
> >
> > I looked into a couple of these but I believe they are for island milling. 
Converting the xy moves from the gerber to the G-code is the easy part the files
are almost exactly the same syntax.
> >
>
> I wonder if instead of trying to do cartesian scans, put the board on some
sort of a spinning disk and run the laser in a radial direction or a polar scan.
Basically what is done on a DVD writer. You could keep the .001 spot size and
just spiral in.
> That way you are not wasting time with a bunch of stop and start motion. May
be easier to construct as well.
>

Volkan Sahin wrote:
>

> I added laser to the side of inkjet head and I'm using raster scanning
> method to expose photoresist.
> I've the same idea to use polygon mirrors of a old laser printer. I've
> one Brother printer which has an aluminum mirror (most of them have a
> copper or gold plated mirror on  aluminum because of IR laser) and
> plastic lenses it seems it is possible to use with blue laser. I did
> some rough measurements and I saw that on optical path I'm loosing ~30%
> of the power most of it is because of diagonal mirrors because of that I
> left it for a future project.
>

The polygon mirror concept sounds more difficult to implement.
How about a large diameter disc with a laser diode mounted on the
perimeter. The PCB moves linear to the disc. Software would compensate
for uniform exposure energy.

Assume that:

Resolution = 0.005cm (50um)
Disc diameter  = 15cm
Energy 	 = 60mj/cm^2
Laser power  = 85mW

Then

maximum disc RPM
	 = 60 * 1cm/0.005cm / (60/85 * 15*1)
	 = 1133

1000 RPM sounds reasonable.

Hello Dave,
There are  some  poor man's method for the power measurement check Sam's
Laser, so many information exist. I'm always using goggles during tests. Here is
the trick for the focus adjustment, print on  thermal fax paper and check it
under microscope.
 
Volkan
 

--- On Fri, 11/13/09, pork_u_pine2000 <wittend@...> wrote:

From: pork_u_pine2000 <wittend@...>
Subject: [Homebrew_PCBs] Re: Making PCB using these new 405nm LASER Diodes
To: Homebrew_PCBs@yahoogroups.com
Date: Friday, November 13, 2009, 12:31 PM







 













--- In Homebrew_PCBs@ yahoogroups. com, Volkan Sahin <v_sahin@... > wrote:

>

> There is nothing wrong with dryfilm. Only side effect can be its thickness.

> It is thicker than liquid photoresist. I've used dichromated PVA in order to
avoid shelf life limitation. Whenever you need photoresist you can mix PVA with
dichromate and it is ready, the problem is dichromate is not an environmentally
safe chemical. Now I'll try AQ 3000.

> I used dryfilm before and faced a lot of problems to protect PTH holes but it
was ~8 years before may be new ones are better.

> I added laser to the side of inkjet head and I'm using raster scanning method
to expose photoresist.

> I've the same idea to use polygon mirrors of a old laser printer. I've one
Brother printer which has an aluminum mirror (most of them have a copper or gold
plated mirror on  aluminum because of IR laser) and plastic lenses it seems
it is possible to use with blue laser. I did some rough measurements and I saw
that on optical path I'm loosing ~30% of the power most of it is because of
diagonal mirrors because of that I left it for a future project.



...



One difficulty that I have worried about using diode lasers is focusing and
power measurement.  I don't have any tools that are specifically useful for
this.  Besides not wanting to stare at a focused UV laser spot while doing
adjustments, at 405 nm a lot of materials (including the laser potting) begin to
fluoresce and emit visible wavelengths in random directions.



What do you use?



-- Dave

























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

The tricky bit is keeping the exposure times reasonably equal. The disk
would have to speed up as the laser approaches the center line. Nice
idea though...

Les

javaguy11111 wrote:
>
> --- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@...> wrote:
>> I looked into a couple of these but I believe they are for island milling. 
Converting the xy moves from the gerber to the G-code is the easy part the files
are almost exactly the same syntax.
>>
>
> I wonder if instead of trying to do cartesian scans, put the board on some
sort of a spinning disk and run the laser in a radial direction or a polar scan.
Basically what is done on a DVD writer. You could keep the .001 spot size and
just spiral in.
> That way you are not wasting time with a bunch of stop and start motion. May
be easier to construct as well.

Henry,
I will have to look at the bmp to raster path.  I haven't played with Mach all
that much so I don't know how it imports a raster.  Do you run the raster
throuhg LazyCam to generate the G-Code for Mach or does Mach import a raster
file directly?

What I can't do is have the mill write a raster that would be way too slow and
hard on the mill.

Craig

--- In Homebrew_PCBs@yahoogroups.com, Henry Liu <henryjliu@...> wrote:
>
> I think it'd be way less work to just export gerber as BMP and raster scan.
>
> Mach3 has raster scan capability from a bmp.
>
> Easy solution.
> On Fri, Nov 13, 2009 at 12:21 PM, designer_craig <cs6061@...> wrote:
>
> >
> >

--- In Homebrew_PCBs@yahoogroups.com, "designer_craig" <cs6061@...> wrote:
>
> I looked into a couple of these but I believe they are for island milling. 
Converting the xy moves from the gerber to the G-code is the easy part the files
are almost exactly the same syntax.
>

I wonder if instead of trying to do cartesian scans, put the board on some sort
of a spinning disk and run the laser in a radial direction or a polar scan.
Basically what is done on a DVD writer. You could keep the .001 spot size and
just spiral in.
That way you are not wasting time with a bunch of stop and start motion. May be
easier to construct as well.

--- In Homebrew_PCBs@yahoogroups.com, Volkan Sahin <v_sahin@...> wrote:
>
> There is nothing wrong with dryfilm. Only side effect can be its thickness.
> It is thicker than liquid photoresist. I've used dichromated PVA in order to
avoid shelf life limitation. Whenever you need photoresist you can mix PVA with
dichromate and it is ready, the problem is dichromate is not an environmentally
safe chemical. Now I'll try AQ 3000.
> I used dryfilm before and faced a lot of problems to protect PTH holes but it
was ~8 years before may be new ones are better.
> I added laser to the side of inkjet head and I'm using raster scanning method
to expose photoresist.
> I've the same idea to use polygon mirrors of a old laser printer. I've one
Brother printer which has an aluminum mirror (most of them have a copper or gold
plated mirror on  aluminum because of IR laser) and plastic lenses it seems it
is possible to use with blue laser. I did some rough measurements and I saw that
on optical path I'm loosing ~30% of the power most of it is because of diagonal
mirrors because of that I left it for a future project.

...

One difficulty that I have worried about using diode lasers is focusing and
power measurement.  I don't have any tools that are specifically useful for
this.  Besides not wanting to stare at a focused UV laser spot while doing
adjustments, at 405 nm a lot of materials (including the laser potting) begin to
fluoresce and emit visible wavelengths in random directions.

What do you use?

-- Dave

I think it'd be way less work to just export gerber as BMP and raster scan.

Mach3 has raster scan capability from a bmp.

Easy solution.
On Fri, Nov 13, 2009 at 12:21 PM, designer_craig <cs6061@...> wrote:

>
>
> I looked into a couple of these but I believe they are for island milling.
> Converting the xy moves from the gerber to the G-code is the easy part the
> files are almost exactly the same syntax.
>
> Its the aperture definitions that cause the problem. The origional photo
> plotters used an aperture wheel to project the correct spot size for the
> trace width and donut pads. But with the laser I will need to write macros
> to draw these from a single .001" dia spot. I took a look at Diptrace's
> Gerber output and currently they don't do anything exotic just x-y moves and
> apeture settings. For me to write and 8mill wide trace I will have to do the
> xy move 8 times with .001 offsets between writes. If this works out to be
> too slow I may have to increase the spot size somewhat. Would be nice to
> figure out how to have several different spot sizes. I guess one could use
> multiple laser diodes and just select the best one for the task at hand. It
> would be no problem selecting the correct diode in the G-code.
>
> Craig
>
> --- In Homebrew_PCBs@yahoogroups.com <Homebrew_PCBs%40yahoogroups.com>,
> Henry Liu <henryjliu@...> wrote:
> >
> > For your problem to convert to Gcode from gerber, there are three ways:
> > -pcb-gcode (works ok but in Eagle)
> > -export to DXF then into Cam package like LazyCAM with Mach3
> > -some commerical package made to CNC mill out pcbs from gerbers (forget
> the
> > name, was on pcb-gcode group)
> >
>  > On Fri, Nov 13, 2009 at 11:21 AM, designer_craig <cs6061@...> wrote:
> >
> > >
> > >
> > > I had the same idea last spring and purchased a 405nm laser diode with
> > > holder/lense and some Riston film off ebay. I added a heat sink to the
> > > holder and have driven it up to 110ma. At that power level it will burn
> > > through paper, so I have no doubts that it should harden the photo
> resist. I
> > > did some initial crude calculations based on the Riston data and
> estimated
> > > diode power that led me to believe it would be possible to write a
> .001" dia
> > > spot at 80"/sec.
> > >
> > > My initial plan is not to raster scan the board but to vector draw the
> > > pattern using my Bridgeport mill that is currently being converted to
> CNC. I
> > > will need to write some code to convert the Gerber photo plot file to a
> > > G-Code file to drive the mill. These files are very similar, the Gerber
> > > format being an offshoot of the G-code format. Since I plann on using a
> > > fixed spot size, wide traces will need multiple passes as will donuts
> etc.
> > > This all has to be coded in the conversion program.
> > >
> > > Currently I am working on the mill's CNC conversion and have not done
> any
> > > testing on the direct exposure part of the project. It will be a couple
> of
> > > months before the mill is ready for PCB testing.
> > >
> > > Issues to be resolved:
> > > 1.Is the exposure of photo resist linear ie. is high power UV for a
> short
> > > time the same as low power UV for a longer time.
> > >
> > > 2.Code to make multiple passes for trace and shape widths from the
> point
> > > gerber data.
> > >
> > > 3.How to get a .001" dia round spot. The laser diode output is not
> round.
> > > How to measure the spot dia.
> > >
> > > 4.How long will it take to expose a 3'x5" board?
> > >
> > > Craig
> > >
> > >
> > >
> > >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>


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

designer_craig wrote:
>
> Issues to be resolved:
> 1.Is the exposure of photo resist linear ie. is high power UV for a
> short time the same as low power UV for a longer time.

No, but I think if the intensity causes polymerisation under 30 seconds
or so then it is linear. (i.e exposure time = 1/intensity).
I discovered this when experimenting with UV LEDs, and noticed that if
the intensity was below a certain level then no amount of exposure time
(exampled > 1 day) would polymerise. It seemed photo polymerisation
needed to be under 3~5 minutes or it just didn't happen. My guess is a
slow side reaction happening during exposure that mitigates photo
sensitivity. Maybe oxygen diffusion through the mylar film.


> 2.Code to make multiple passes for trace and shape widths from the point
> gerber data.
>
> 3.How to get a .001" dia round spot. The laser diode output is not
> round. How to measure the spot dia.

microscope slide and a microscope. Or better is expose point on
photoresist and develop, then view photoresist under microscope.

>
> 4.How long will it take to expose a 3'x5" board?
>

Assuming a 60mj/cm^2 exposure requirement, and 85 mW source then your
7.5*12.5cm = 93cm^2 PCB will take  60/85*93 = 65 seconds.

--- In Homebrew_PCBs@yahoogroups.com, "lmri2071" <lmri2071@...> wrote:
>
>
> I had this idea about seven years ago. But at that time the Laser Diodes
> of 405nm were impossible to obtain (USD$4000).

...

I have been experimenting with ammonium di-(or bi- same thing) chromate and
gelatin emulsions off and on for about a year and a half.  Though I don't know
the chemistry very well, it seems that potassium, sodium or ammonium dichromate
all have the ability to crosslink (harden) any number of organic materials when
exposed to light.

I use fish-gelatin (aka fish-glue) which was once used to make the masks in TV
picture tubes and other chemical milling processes.  It is a kind of gelatin
made from fish from Northern oceans. Due to its amino acid composition remains
liquid at room temperature.  I have no special reason to think that it is
necessary.  It wasn't terribly expensive, but then neither is Knorr's at the
grocer's.

The Dichromates are indeed hazardous, as is any form of hexavalent chromium. 
Much of the negative experience with it comes from the plating industry, I
believe.

That said, I worked with it a lot during my squandered youth, experimenting with
gum-bichromate printing of photos.  I gave that up one day when I inhaled enough
of the powder to give me a headache and make me nauseous.  I'm much more careful
now.

The induction period for most chemical carcinogens is hopefully less than twenty
years.  Now forty years on I believe that something else will probably get me
first.

-- Dave

I looked into a couple of these but I believe they are for island milling. 
Converting the xy moves from the gerber to the G-code is the easy part the files
are almost exactly the same syntax.

Its the aperture definitions that cause the problem. The origional photo
plotters used an aperture wheel to project the correct spot size for the trace
width and donut pads. But with the laser I will need to write macros to draw
these from a single .001" dia spot. I took a look at Diptrace's Gerber output
and currently they don't do anything exotic just x-y moves and apeture settings.
For me to write and 8mill wide trace I will have to do the xy move 8 times with
.001 offsets between writes. If this works out to be too slow I may have to
increase the spot size somewhat. Would be nice to figure out how to have several
different spot sizes.  I guess one could use multiple laser diodes and just
select the best one for the task at hand. It would be no problem selecting the
correct diode in the G-code.


Craig

--- In Homebrew_PCBs@yahoogroups.com, Henry Liu <henryjliu@...> wrote:
>
> For your problem to convert to Gcode from gerber, there are three ways:
> -pcb-gcode (works ok but in Eagle)
> -export to DXF then into Cam package like LazyCAM with Mach3
> -some commerical package made to CNC mill out pcbs from gerbers (forget the
> name, was on pcb-gcode group)
>
> On Fri, Nov 13, 2009 at 11:21 AM, designer_craig <cs6061@...> wrote:
>
> >
> >
> > I had the same idea last spring and purchased a 405nm laser diode with
> > holder/lense and some Riston film off ebay. I added a heat sink to the
> > holder and have driven it up to 110ma. At that power level it will burn
> > through paper, so I have no doubts that it should harden the photo resist. I
> > did some initial crude calculations based on the Riston data and estimated
> > diode power that led me to believe it would be possible to write a .001" dia
> > spot at 80"/sec.
> >
> > My initial plan is not to raster scan the board but to vector draw the
> > pattern using my Bridgeport mill that is currently being converted to CNC. I
> > will need to write some code to convert the Gerber photo plot file to a
> > G-Code file to drive the mill. These files are very similar, the Gerber
> > format being an offshoot of the G-code format. Since I plann on using a
> > fixed spot size, wide traces will need multiple passes as will donuts etc.
> > This all has to be coded in the conversion program.
> >
> > Currently I am working on the mill's CNC conversion and have not done any
> > testing on the direct exposure part of the project. It will be a couple of
> > months before the mill is ready for PCB testing.
> >
> > Issues to be resolved:
> > 1.Is the exposure of photo resist linear ie. is high power UV for a short
> > time the same as low power UV for a longer time.
> >
> > 2.Code to make multiple passes for trace and shape widths from the point
> > gerber data.
> >
> > 3.How to get a .001" dia round spot. The laser diode output is not round.
> > How to measure the spot dia.
> >
> > 4.How long will it take to expose a 3'x5" board?
> >
> > Craig
> >
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>

For your problem to convert to Gcode from gerber, there are three ways:
-pcb-gcode (works ok but in Eagle)
-export to DXF then into Cam package like LazyCAM with Mach3
-some commerical package made to CNC mill out pcbs from gerbers (forget the
name, was on pcb-gcode group)

On Fri, Nov 13, 2009 at 11:21 AM, designer_craig <cs6061@...> wrote:

>
>
> I had the same idea last spring and purchased a 405nm laser diode with
> holder/lense and some Riston film off ebay. I added a heat sink to the
> holder and have driven it up to 110ma. At that power level it will burn
> through paper, so I have no doubts that it should harden the photo resist. I
> did some initial crude calculations based on the Riston data and estimated
> diode power that led me to believe it would be possible to write a .001" dia
> spot at 80"/sec.
>
> My initial plan is not to raster scan the board but to vector draw the
> pattern using my Bridgeport mill that is currently being converted to CNC. I
> will need to write some code to convert the Gerber photo plot file to a
> G-Code file to drive the mill. These files are very similar, the Gerber
> format being an offshoot of the G-code format. Since I plann on using a
> fixed spot size, wide traces will need multiple passes as will donuts etc.
> This all has to be coded in the conversion program.
>
> Currently I am working on the mill's CNC conversion and have not done any
> testing on the direct exposure part of the project. It will be a couple of
> months before the mill is ready for PCB testing.
>
> Issues to be resolved:
> 1.Is the exposure of photo resist linear ie. is high power UV for a short
> time the same as low power UV for a longer time.
>
> 2.Code to make multiple passes for trace and shape widths from the point
> gerber data.
>
> 3.How to get a .001" dia round spot. The laser diode output is not round.
> How to measure the spot dia.
>
> 4.How long will it take to expose a 3'x5" board?
>
> Craig
>
>
>
>


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

I had the same idea last spring and purchased a 405nm laser diode with
holder/lense and some Riston film off ebay.  I added a heat sink to the holder
and have driven it up to 110ma.  At that power level it will burn through paper,
so I have no doubts that it should harden the photo resist. I did some initial
crude calculations based on the Riston data and estimated diode power that led
me to believe it would be possible to write a .001" dia spot at 80"/sec.

My initial plan is not to raster scan the board but to vector draw the pattern
using my Bridgeport mill that is currently being converted to CNC. I will need
to write some code to convert the Gerber photo plot file to a G-Code file to
drive the mill.  These files are very similar, the Gerber format being an
offshoot of the G-code format. Since I plann on using a fixed spot size, wide
traces will need multiple passes as will donuts etc. This all has to be coded in
the conversion program.

Currently I am working on the mill's CNC conversion and have not done any
testing on the direct exposure part of the project. It will be a couple of
months before the mill is ready for PCB testing.

Issues to be resolved:
1.Is the exposure of photo resist linear ie. is high power UV for a short time
the same as low power UV for a longer time.

2.Code to make multiple passes for trace and shape widths from the point gerber
data.

3.How to get a .001" dia round spot.  The laser diode output is not round. How
to measure the spot dia.

4.How long will it take to expose a 3'x5" board?

Craig

There is nothing wrong with dryfilm. Only side effect can be its thickness.
It is thicker than liquid photoresist. I've used dichromated PVA in order to
avoid shelf life limitation. Whenever you need photoresist you can mix PVA with
dichromate and it is ready, the problem is dichromate is not an environmentally
safe chemical. Now I'll try AQ 3000.
I used dryfilm before and faced a lot of problems to protect PTH holes but it
was ~8 years before may be new ones are better.
I added laser to the side of inkjet head and I'm using raster scanning method to
expose photoresist.
I've the same idea to use polygon mirrors of a old laser printer. I've one
Brother printer which has an aluminum mirror (most of them have a copper or gold
plated mirror on  aluminum because of IR laser) and plastic lenses it seems it
is possible to use with blue laser. I did some rough measurements and I saw that
on optical path I'm loosing ~30% of the power most of it is because of diagonal
mirrors because of that I left it for a future project.   

Volkan

--- On Fri, 11/13/09, Adam Seychell <a_seychell@...> wrote:

From: Adam Seychell <a_seychell@...>
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: Homebrew_PCBs@yahoogroups.com
Date: Friday, November 13, 2009, 2:26 AM







 









       Volkan Sahin wrote:

>

>

> I've a working prototype. I'm using 150mw 405nm blue ray laser diode.

> Without complicated optics I can get ~3 mil trace width/space.

> Currently, I'm using  Dichromated PVA  based homemade photoresist.  The

> problem is without  polygon mirror scanner, it is very slow but result

> is impressive. The exposure time required for  1.5 mil spot is ~20

> microseconds.

> Volkan

>



What's wrong with using dry film photoresist ?

Its relatively cheap (under 10% cost of FR4 PCB material per unit area)

easy to apply, fairly sensitive to 405nm, highly uniform and the ability

to tent holes for the PTH panel plating method.



How are you positioning the laser ?

Would it be difficult to use parts off an laser printer to make a

polygon mirror scanner. In that case only 1 axis movement is needed for

the PCB.  My inkjet printer is currently the limiting factor for

line/space widths, although 0.2mm (8mil) are quite reliable and adequate.

























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

Thank you for the link, Volkan.

In my occasional searches over the last few years (mostly for terms like
"homemade photoresist") I hadn't found that.  Excellent information.  I'll also
check on the AQ 3000; I've heard it mentioned (probably on this group) recently.

Donald.

----- Original Message -----
From: "Volkan Sahin" <v_sahin@...>
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, November 13, 2009 1:10:19 AM GMT -05:00 US/Canada Eastern
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes

Hello Donald,

There is no magic for the formula check
http://www.holowiki.com/index.php/Dichromated_Gelatin_Chemistry they have
detailed information on it. I'm using PVA instead of gelatin. The problem is you
need to be careful using dichromate, it is not environmentally safe disposing
requires care. I'm always keeping water used for development in separate
container for  recycling/disposal center.
I've decided to switch another photoresist which is environmentally safe,
they're also selling it on e-bay  AQ 3000 Waterborne Photoresist,  it is
easier and much more sensitive than DCG.

Volkan


--- On Thu, 11/12/09, Donald H Locker <dhlocker@...> wrote:

From: Donald H Locker <dhlocker@...>
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Date: Thursday, November 12, 2009, 6:09 PM

Hello, Volkan.

Looks like you have your fingers in several pots (homebrew pcbs, direct print
resist, homemade photo resist).  I love it.

Are you willing to tell us more about your formula and processing for the
homemade dichromated PVA resist?  A friend (30 years ago) did some silkscreen
work using (IIRC) Elmer's glue, which is a PVA product.  What else is involved? 
Or a pointer to where you have already told everyone and I wasn't watching. :)

Thanks much,
Donald.

----- Original Message -----

From: "Volkan Sahin" <v_sahin@yahoo. com>

To: "Homebrew PCBs" <Homebrew_PCBs@ yahoogroups. com>

Sent: Thursday, November 12, 2009 5:46:45 PM GMT -05:00 US/Canada Eastern

Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes

I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without
complicated optics I can get ~3 mil trace width/space. Currently, I'm using 
Dichromated PVA  based homemade photoresist.  The problem is without  polygon
mirror scanner, it is very slow but result is impressive. The exposure time
required for  1.5 mil spot is ~20 microseconds.

Volkan


[snip]

Volkan Sahin wrote:
>
>
> I've a working prototype. I'm using 150mw 405nm blue ray laser diode.
> Without complicated optics I can get ~3 mil trace width/space.
> Currently, I'm using  Dichromated PVA  based homemade photoresist.  The
> problem is without  polygon mirror scanner, it is very slow but result
> is impressive. The exposure time required for  1.5 mil spot is ~20
> microseconds.
> Volkan
>

What's wrong with using dry film photoresist ?
Its relatively cheap (under 10% cost of FR4 PCB material per unit area)
easy to apply, fairly sensitive to 405nm, highly uniform and the ability
to tent holes for the PTH panel plating method.

How are you positioning the laser ?
Would it be difficult to use parts off an laser printer to make a
polygon mirror scanner. In that case only 1 axis movement is needed for
the PCB.  My inkjet printer is currently the limiting factor for
line/space widths, although 0.2mm (8mil) are quite reliable and adequate.

Hello Donald,

There is no magic for the formula check
http://www.holowiki.com/index.php/Dichromated_Gelatin_Chemistry they have
detailed information on it. I'm using PVA instead of gelatin. The problem is you
need to be careful using dichromate, it is not environmentally safe disposing
requires care. I'm always keeping water used for development in separate
container for  recycling/disposal center.
I've decided to switch another photoresist which is environmentally safe,
they're also selling it on e-bay  AQ 3000 Waterborne Photoresist,  it is
easier and much more sensitive than DCG.

Volkan


--- On Thu, 11/12/09, Donald H Locker <dhlocker@...> wrote:

From: Donald H Locker <dhlocker@...>
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Date: Thursday, November 12, 2009, 6:09 PM







 









       Hello, Volkan.



Looks like you have your fingers in several pots (homebrew pcbs, direct print
resist, homemade photo resist).  I love it.



Are you willing to tell us more about your formula and processing for the
homemade dichromated PVA resist?  A friend (30 years ago) did some silkscreen
work using (IIRC) Elmer's glue, which is a PVA product.  What else is involved? 
Or a pointer to where you have already told everyone and I wasn't watching. :)



Thanks much,

Donald.



----- Original Message -----

From: "Volkan Sahin" <v_sahin@yahoo. com>

To: "Homebrew PCBs" <Homebrew_PCBs@ yahoogroups. com>

Sent: Thursday, November 12, 2009 5:46:45 PM GMT -05:00 US/Canada Eastern

Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes



I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without
complicated optics I can get ~3 mil trace width/space. Currently, I'm using 
Dichromated PVA  based homemade photoresist.  The problem is without  polygon
mirror scanner, it is very slow but result is impressive. The exposure time
required for  1.5 mil spot is ~20 microseconds.

Volkan



--- On Thu, 11/12/09, lmri2071 <lmri2071@yahoo. com> wrote:



From: lmri2071 <lmri2071@yahoo. com>

Subject: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes

To: Homebrew_PCBs@ yahoogroups. com

Date: Thursday, November 12, 2009, 8:38 AM



 



I had this idea about seven years ago. But at that time the Laser Diodes



of 405nm were impossible to obtain (USD$4000).  Since last year, I have



taken this idea again, because now one can buy those laser diodes around



USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys



experimenting with this, but I have not see the results. Also I read



about a french engineer who made some experiments with UV LEDs coupled



with a fibre optic. I have a Polish paper which expose the use of this



idea to get 50um (2 mils) clear cut beatiful traces, but they use very



expensive optics ( telecentric lenses, glavos and others things which



are too costly for the DIYer ).



Now I struggling with optics.  When I get some control of the LASER beam



waist, I gonna put my laser module in a CNC engraver.



There are anyone working on that in this group?



[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

























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

The intention is to polimerize/depolimerize the etchresist and solder mask.  In
the industrie is know as LDI (Laser Direct Imaging). Before the blue-violet
LASER diodes the industrie use Argon and Kripton LASERS.  But being gas LASERs,
the method of modulation was very complex and costly.  Working with a 405nm
LASER diode is far simpler.

Lucho

--- In Homebrew_PCBs@yahoogroups.com, Henry Liu <henryjliu@...> wrote:
>
> I think you need a 3W UV laser to ablate copper.
>
> I saw a UV laser at Fabtech with galvos in an enclosed case.  No moving
> parts.  It was sweet.  They guy put a pen in and typed up my name and it
> engraved it in about 3 seconds.  Super clean not like CO2 cuts.  I can't
> remember if the machine was $30,000 or if that was just the diode without
> the galvos.
>
> http://www.lpkfusa.com/microline/pl_u.htm
> uses 3W UV laser does 1mil traces/1mil spacing
> Costs $220,000
>
>
> http://www.lpkfusa.com/microline/pl_s.htm
> uses 10W YAG laser
> costs $120,000
>
> If you can get the UV to fire safely, I sell you a XY overhead complete
> gantry for ~$1200 with motors and control card.  This gantry is currently
> used on my 50W CO2 laser (which copper doesn't absorb).
>
>
>
>
>
>
> On Thu, Nov 12, 2009 at 8:38 AM, lmri2071 <lmri2071@...> wrote:
>
> >
> >
> >
> > I had this idea about seven years ago. But at that time the Laser Diodes
> > of 405nm were impossible to obtain (USD$4000). Since last year, I have
> > taken this idea again, because now one can buy those laser diodes around
> > USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys
> > experimenting with this, but I have not see the results. Also I read
> > about a french engineer who made some experiments with UV LEDs coupled
> > with a fibre optic. I have a Polish paper which expose the use of this
> > idea to get 50um (2 mils) clear cut beatiful traces, but they use very
> > expensive optics ( telecentric lenses, glavos and others things which
> > are too costly for the DIYer ).
> >
> > Now I struggling with optics. When I get some control of the LASER beam
> > waist, I gonna put my laser module in a CNC engraver.
> >
> > There are anyone working on that in this group?
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>

Excellent news, I thought that Bichromate photoresist needs a high energy
density. I gonna try with dry films for etch resist and solder mask with a LASER
diode of 65 mW to 85 mW. They are  sensitive between 350nm to 420nm wavelength
and have an energy density between 25 to 60 mJ/cm2 (Think & Tinker Ltd.). At the
begining I though to modify an old LASER printer (replace the IR diode) and try.
Is good to know that you get 3 mils with your own implementation.

Lucho

--- In Homebrew_PCBs@yahoogroups.com, Volkan Sahin <v_sahin@...> wrote:
>
> I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without
complicated optics I can get ~3 mil trace width/space. Currently, I'm using 
Dichromated PVA  based homemade photoresist.  The problem is without  polygon
mirror scanner, it is very slow but result is impressive. The exposure time
required for  1.5 mil spot is ~20 microseconds.
> Volkan
>
> --- On Thu, 11/12/09, lmri2071 <lmri2071@...> wrote:
>
> From: lmri2071 <lmri2071@...>
> Subject: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
> To: Homebrew_PCBs@yahoogroups.com
> Date: Thursday, November 12, 2009, 8:38 AM
>
>
>
>
>
>
>
>  
>
>
>
>
>
>
>
>
>
>
>
> I had this idea about seven years ago. But at that time the Laser Diodes
>
> of 405nm were impossible to obtain (USD$4000).  Since last year, I have
>
> taken this idea again, because now one can buy those laser diodes around
>
> USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys
>
> experimenting with this, but I have not see the results. Also I read
>
> about a french engineer who made some experiments with UV LEDs coupled
>
> with a fibre optic. I have a Polish paper which expose the use of this
>
> idea to get 50um (2 mils) clear cut beatiful traces, but they use very
>
> expensive optics ( telecentric lenses, glavos and others things which
>
> are too costly for the DIYer ).
>
>
>
> Now I struggling with optics.  When I get some control of the LASER beam
>
> waist, I gonna put my laser module in a CNC engraver.
>
>
>
> There are anyone working on that in this group?
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

Hello, Volkan.

Looks like you have your fingers in several pots (homebrew pcbs, direct print
resist, homemade photo resist).  I love it.

Are you willing to tell us more about your formula and processing for the
homemade dichromated PVA resist?  A friend (30 years ago) did some silkscreen
work using (IIRC) Elmer's glue, which is a PVA product.  What else is involved? 
Or a pointer to where you have already told everyone and I wasn't watching. :)

Thanks much,
Donald.


----- Original Message -----
From: "Volkan Sahin" <v_sahin@...>
To: "Homebrew PCBs" <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, November 12, 2009 5:46:45 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes

I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without
complicated optics I can get ~3 mil trace width/space. Currently, I'm using 
Dichromated PVA  based homemade photoresist.  The problem is without  polygon
mirror scanner, it is very slow but result is impressive. The exposure time
required for  1.5 mil spot is ~20 microseconds.
Volkan

--- On Thu, 11/12/09, lmri2071 <lmri2071@...> wrote:

From: lmri2071 <lmri2071@...>
Subject: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: Homebrew_PCBs@yahoogroups.com
Date: Thursday, November 12, 2009, 8:38 AM







 











I had this idea about seven years ago. But at that time the Laser Diodes

of 405nm were impossible to obtain (USD$4000).  Since last year, I have

taken this idea again, because now one can buy those laser diodes around

USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys

experimenting with this, but I have not see the results. Also I read

about a french engineer who made some experiments with UV LEDs coupled

with a fibre optic. I have a Polish paper which expose the use of this

idea to get 50um (2 mils) clear cut beatiful traces, but they use very

expensive optics ( telecentric lenses, glavos and others things which

are too costly for the DIYer ).



Now I struggling with optics.  When I get some control of the LASER beam

waist, I gonna put my laser module in a CNC engraver.



There are anyone working on that in this group?

























[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

Henry Liu wrote:
> I sell you a XY overhead complete gantry for ~$1200

Isn't there some rule which limits selling/marketing messages to one per
month?



Volkan Sahin wrote:
> I'm using  Dichromated PVA  based homemade photoresist.

http://www.htp.ch/lib/pdf/Liquid%20resist%20for%20PCM.pdf
Once i found this, useful for who like me don't know really much about
photoresists (most interesting after page 4).

It's used for UV exposure.

--- On Thu, 11/12/09, javaguy11111 <javaguy11111@...> wrote:

From: javaguy11111 <javaguy11111@...>
Subject: [Homebrew_PCBs] Re: Making PCB using these new 405nm LASER Diodes
To: Homebrew_PCBs@yahoogroups.com
Date: Thursday, November 12, 2009, 3:17 PM







 









       --- In Homebrew_PCBs@ yahoogroups. com, Volkan Sahin <v_sahin@... > wrote:

>

> I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without
complicated optics I can get ~3 mil trace width/space. Currently, I'm using 
Dichromated PVA  based homemade photoresist.  The problem is without 
polygon mirror scanner, it is very slow but result is impressive. The exposure
time required for  1.5 mil spot is ~20 microseconds.

> Volkan

>



I assume that you are doing UV exposure as opposed to ablation as mentioned in
the earlier post.

























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

--- In Homebrew_PCBs@yahoogroups.com, Volkan Sahin <v_sahin@...> wrote:
>
> I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without
complicated optics I can get ~3 mil trace width/space. Currently, I'm using 
Dichromated PVA  based homemade photoresist.  The problem is without  polygon
mirror scanner, it is very slow but result is impressive. The exposure time
required for  1.5 mil spot is ~20 microseconds.
> Volkan
>

I assume that you are doing UV exposure as opposed to ablation as mentioned in
the earlier post.

Can your laser ablate the copper or just hardens the resist?

If the former, I need to buy some blue lasers to try.
On Thu, Nov 12, 2009 at 2:46 PM, Volkan Sahin <v_sahin@...> wrote:

>
>
> I've a working prototype. I'm using 150mw 405nm blue ray laser diode.
> Without complicated optics I can get ~3 mil trace width/space. Currently,
> I'm using  Dichromated PVA  based homemade photoresist.  The problem is
> without  polygon mirror scanner, it is very slow but result is impressive.
> The exposure time required for  1.5 mil spot is ~20 microseconds.
> Volkan
>
> --- On Thu, 11/12/09, lmri2071 <lmri2071@... <lmri2071%40yahoo.com>>
> wrote:
>
> From: lmri2071 <lmri2071@... <lmri2071%40yahoo.com>>
> Subject: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
> To: Homebrew_PCBs@yahoogroups.com <Homebrew_PCBs%40yahoogroups.com>
> Date: Thursday, November 12, 2009, 8:38 AM
>
>
>
>
> I had this idea about seven years ago. But at that time the Laser Diodes
>
> of 405nm were impossible to obtain (USD$4000). Since last year, I have
>
> taken this idea again, because now one can buy those laser diodes around
>
> USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys
>
> experimenting with this, but I have not see the results. Also I read
>
> about a french engineer who made some experiments with UV LEDs coupled
>
> with a fibre optic. I have a Polish paper which expose the use of this
>
> idea to get 50um (2 mils) clear cut beatiful traces, but they use very
>
> expensive optics ( telecentric lenses, glavos and others things which
>
> are too costly for the DIYer ).
>
> Now I struggling with optics. When I get some control of the LASER beam
>
> waist, I gonna put my laser module in a CNC engraver.
>
> There are anyone working on that in this group?
>
> [Non-text portions of this message have been removed]
>
>
>


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

I've a working prototype. I'm using 150mw 405nm blue ray laser diode. Without
complicated optics I can get ~3 mil trace width/space. Currently, I'm using 
Dichromated PVA  based homemade photoresist.  The problem is without  polygon
mirror scanner, it is very slow but result is impressive. The exposure time
required for  1.5 mil spot is ~20 microseconds.
Volkan

--- On Thu, 11/12/09, lmri2071 <lmri2071@...> wrote:

From: lmri2071 <lmri2071@...>
Subject: [Homebrew_PCBs] Making PCB using these new 405nm LASER Diodes
To: Homebrew_PCBs@yahoogroups.com
Date: Thursday, November 12, 2009, 8:38 AM







 











I had this idea about seven years ago. But at that time the Laser Diodes

of 405nm were impossible to obtain (USD$4000).  Since last year, I have

taken this idea again, because now one can buy those laser diodes around

USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys

experimenting with this, but I have not see the results. Also I read

about a french engineer who made some experiments with UV LEDs coupled

with a fibre optic. I have a Polish paper which expose the use of this

idea to get 50um (2 mils) clear cut beatiful traces, but they use very

expensive optics ( telecentric lenses, glavos and others things which

are too costly for the DIYer ).



Now I struggling with optics.  When I get some control of the LASER beam

waist, I gonna put my laser module in a CNC engraver.



There are anyone working on that in this group?

























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

I think you need a 3W UV laser to ablate copper.

I saw a UV laser at Fabtech with galvos in an enclosed case.  No moving
parts.  It was sweet.  They guy put a pen in and typed up my name and it
engraved it in about 3 seconds.  Super clean not like CO2 cuts.  I can't
remember if the machine was $30,000 or if that was just the diode without
the galvos.

http://www.lpkfusa.com/microline/pl_u.htm
uses 3W UV laser does 1mil traces/1mil spacing
Costs $220,000


http://www.lpkfusa.com/microline/pl_s.htm
uses 10W YAG laser
costs $120,000

If you can get the UV to fire safely, I sell you a XY overhead complete
gantry for ~$1200 with motors and control card.  This gantry is currently
used on my 50W CO2 laser (which copper doesn't absorb).






On Thu, Nov 12, 2009 at 8:38 AM, lmri2071 <lmri2071@...> wrote:

>
>
>
> I had this idea about seven years ago. But at that time the Laser Diodes
> of 405nm were impossible to obtain (USD$4000). Since last year, I have
> taken this idea again, because now one can buy those laser diodes around
> USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys
> experimenting with this, but I have not see the results. Also I read
> about a french engineer who made some experiments with UV LEDs coupled
> with a fibre optic. I have a Polish paper which expose the use of this
> idea to get 50um (2 mils) clear cut beatiful traces, but they use very
> expensive optics ( telecentric lenses, glavos and others things which
> are too costly for the DIYer ).
>
> Now I struggling with optics. When I get some control of the LASER beam
> waist, I gonna put my laser module in a CNC engraver.
>
> There are anyone working on that in this group?
>
>
>


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

I had this idea about seven years ago. But at that time the Laser Diodes
of 405nm were impossible to obtain (USD$4000).  Since last year, I have
taken this idea again, because now one can buy those laser diodes around
USD$40 (85mW) in eBay. I saw in web (youtube) some germans guys
experimenting with this, but I have not see the results. Also I read
about a french engineer who made some experiments with UV LEDs coupled
with a fibre optic. I have a Polish paper which expose the use of this
idea to get 50um (2 mils) clear cut beatiful traces, but they use very
expensive optics ( telecentric lenses, glavos and others things which
are too costly for the DIYer ).

Now I struggling with optics.  When I get some control of the LASER beam
waist, I gonna put my laser module in a CNC engraver.

There are anyone working on that in this group?

Hi Andy, I've been a lurker here a long time!  Just now having some questions
and getting around to actually doing something with my circuit.
 
Yeah the board I was asking about is for the "switching and Capacitor Bank" for
my Pulsed EDM.  The control circuits will be on a strip board for now, in case
I have to make any changes. (but of course it will be perfect the first time 
;-)  )
 
Cary

--- On Tue, 11/10/09, awakephd <a_wake@...> wrote:


From: awakephd <a_wake@...>
Subject: [Homebrew_PCBs] Re: tape for resist?
To: Homebrew_PCBs@yahoogroups.com
Date: Tuesday, November 10, 2009, 5:02 PM


 



Hi, Cary,

Welcome to Homebrew_PCBs! Are you planning to make a board for an EDM
controller? I keep wanting to update my design and put it on a pcb, but just
haven't had time yet.

Speaking of time -- honestly, I think toner transfer would still be easier and
quicker than messing with tape, etc. If you were wanting to block a large area,
then the tape/contact paper/etc. would be great. But if you are wanting to make
traces -- even straight, fat traces -- I think trying to get the tape cut and
laid out would be a pain. Meanwhile, toner transfer is really very easy.

The only thing that would be easier than toner transfer would be the Sharpie
pen, or similar resist pen -- just draw your traces with a ruler, or freehand if
you don't need them to be straight.

Whichever way you decide to go, good luck. Ask back as you have questions!

Andy

--- In Homebrew_PCBs@ yahoogroups. com, cary heestand <c.hhestand@ ...> wrote:
>
> Thank you all for the great replies!
>  
> Leakage on the edges won't be a problem.
>  
> I originally was going to use a "ball shaped burr" in a dremel tool and still
might go that way.  But then thought about using tape and etching.
>  
> I didn't know you could use a Sharpie on it's own.  I thought that was just
for repair of toner transfer.
>  
> Spray paint will work?  For what I have to do that might be the way to
go.  Then I could just remove the paint where the pads are and leave the rest
of paint as a solder mask!
>  
> Again thank you ALL for helping a newbie with my first board.  Even if it
isn't a complicated one!
>  
> Cary
> >
> >Be sure to visit the group home and check for new Links, Files, and Photos:
> >http://groups. yahoo.com/ group/Homebrew_ PCBsYahoo! Groups Links
> >
> >
> >
>
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>








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