Homebrew_PCBs

>I've been making my own PCBs at home for about 40 years, starting by
>painting the pattern onto single-sided PCB material using a fine
>paintbrush and cellulose paint, with ferric chloride or ammonium
>persulphate etchant. I used 0.1" graph paper for designing the layout
>then marked the holes with a centre punch through the paper onto the
>copper surface. I even made a couple of double-sided PCBs using this
>technique, by masking off one side, etching the other side, drilling it,
>and using the drill holes as a guide when painting on the resist on the
>second side. I then masked off the first side with tape to etch the
>second side.
>
>When low-cost CAD software became available (I used Easy-PC from Number
>One Systems for years) I progressed to printing 2:1 artwork on a dot
>matrix printer. I then got a local litho platemaking company to produce
>a 1:1 positive transparency that I used with a home-made UV exposure
>unit and resist-coated PCB material. When I got an ink jet printer I
>found that I could get reasonable results by printing 1:1 artwork onto
>tracing paper.
>
>I now use an old LaserJet IIIp I picked up very cheaply to print 1:1
>onto LaserStar film and expose the PCBs in a home-made UV exposure unit.
>I sometimes use tracing paper (nice and cheap), but find that I get
>better results from the LaserStar film. The CAD software I use is
>Pulsonix, a professional package out of the same stable as Easy-PC. I
>regularly use 12/12 design rules, occasionally going down to 10 mils if
>I need to route tracks between IC pads. Rather than conventional
>positive-resist FR4 PCB material, I usually use something called FPC-16
>which consists of a sandwich of compressed paper between thin layers of
>fibreglass. It's cheaper than FR4 and much easier to cut and drill. It's
>available from Mega Electronics, as is the LaserStar film.
>
>Etching is in ferric chloride. I place the etchant in a small plastic
>food container inside a larger container half-filled with hot water and
>continuously agitate the etchant manually by rocking the container.
>Etching typically takes 5-10 minutes.
>
>I'm quite pleased with the results. I intend to experiment with
>double-sided boards by making a UV exposure unit that can expose both
>sides of the PCB simultaneously. With a better printer and vacuum on the
>UV exposure unit I think I could get 8 mil tracks quite reliably. I've
>heard of other people managing it at home.
>
>Here is an example of one of my PCBs:
>
> http://www.geocities.com/leon_heller/pcb.html
>
>I often use the Pulsonix copper pour facility for this type of board, as
>it makes the routing easier. Cross-hatching is better with a laser
>printer, as they don't tend to print large black areas very well.
>
>Links:
>
>Mega Electronics: http://www.megaelect.demon.co.uk/
>Number One Systems: http://www.numberone.com/
>Pulsonix: http://www.pulsonix.com/
>
>Leon
>--
>Leon Heller, G1HSM
>leon_heller@...
>http://www.geocities.com/leon_heller
>
>
>Be sure to visit the group home and check for new Bookmarks and files:
>http://groups.yahoo.com/group/Homebrew_PCBs
>
>To unsubscribe from this group, send an email to:
>Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
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>
>
>

>
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> Hans Wedemeyer wrote:
>
> > I make double side board all the time. I used to do it the way you
> > mentioned, and even wrote a program for my CNC mill to compensate
> for
> > alignment problems.
> > I found a better way by printing on transparencies and then aligning
>
> > them visually, then stapling them together. Then slide the board in
> > between the transparencies and sandwich the whole lot between two
> plates
> > of glass, and place the sandwich between two lamps
>
> I make boards almost exactly the same way, also using Eagle. I print
> with a
> Brother 5040 laser printer at 1200 dpi on overhead transparency
> slides.
> I've made double sided boards down to 10 mil traces.
>
> I decided to go with Eagle (even though I don't really like its user
> interface because of) its stability, the extensive parts libraries,
> and the
> very active support and user forums. Even if I don't find the exact
> part I
> want in an Eagle library I can usually find something close that I can
> start
> with - much easier than starting from scratch on a new part. And if I
> have a
> question or problem I've always been able to get a quick answer on one
> of
> the forums.
>
> Regarding printing transparencies, one minor irritation I'd like to
> overcome
> is that dark areas on the slides aren't as opaque as I'd like, and
> I've
> needed to double up the top and bottom transparencies, for a stack of
> four,
> which is a little tricky to align and keep aligned.
>
> What media do other people print slides on?
>
> Also, I read somewhere of someone who printed "transparencies" on
> normal
> paper and then made them more transparent by spraying them with some
> solution (maybe spray silicone?). These resulted in very opaque dark
> areas.
> They needed somewhat longer than normal exposures, but produced
> excellent
> boards. I now can't find where I read this, and would love to know
> the
> details of the process. Are any of you familiar with this?
>
> - Chris Graham
>
>
>
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> have all of you professional pcb drill presses or how do you drill your
> boards? (maybe homebuilt ones and a picture of them???)

>
>
>>From: Chris Graham <Chrisgr@...>
>>Reply-To: Homebrew_PCBs@yahoogroups.com
>>To: Homebrew_PCBs@yahoogroups.com
>>Subject: Re: [Homebrew_PCBs] How I make my PCBs
>>Date: Sun, 18 May 2003 08:15:40 -0700
>>
>>Hans Wedemeyer wrote:
>>
>> > I make double side board all the time. I used to do it the way you
>> > mentioned, and even wrote a program for my CNC mill to compensate for
>> > alignment problems.
>> > I found a better way by printing on transparencies and then aligning
>> > them visually, then stapling them together. Then slide the board in
>> > between the transparencies and sandwich the whole lot between two plates
>> > of glass, and place the sandwich between two lamps
>>
>>I make boards almost exactly the same way, also using Eagle. I print with
>>a
>>Brother 5040 laser printer at 1200 dpi on overhead transparency slides.
>>I've made double sided boards down to 10 mil traces.
>>
>>I decided to go with Eagle (even though I don't really like its user
>>interface because of) its stability, the extensive parts libraries, and
>>the
>>very active support and user forums. Even if I don't find the exact part I
>>want in an Eagle library I can usually find something close that I can
>>start
>>with - much easier than starting from scratch on a new part. And if I have
>>a
>>question or problem I've always been able to get a quick answer on one of
>>the forums.
>>
>>Regarding printing transparencies, one minor irritation I'd like to
>>overcome
>>is that dark areas on the slides aren't as opaque as I'd like, and I've
>>needed to double up the top and bottom transparencies, for a stack of four,
>>which is a little tricky to align and keep aligned.
>>
>>What media do other people print slides on?
>>
>>Also, I read somewhere of someone who printed "transparencies" on normal
>>paper and then made them more transparent by spraying them with some
>>solution (maybe spray silicone?). These resulted in very opaque dark
>>areas.
>>They needed somewhat longer than normal exposures, but produced excellent
>>boards. I now can't find where I read this, and would love to know the
>>details of the process. Are any of you familiar with this?
>
>
>ESR (http://www.esr.co.uk) sells a spray to make paper transparent. I
>haven't tried it. I've heard of people using cooking oil, and tried it once;
>it works, but is a bit messy.
>
>
>Leon
>--
>Leon Heller, G1HSM Tel: +44 1424 423947
>Email:leon_heller@...
>My web page: http://www.geocities.com/leon_heller
>
>_________________________________________________________________
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>http://www.msn.co.uk/messenger
>
>
>
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>
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>
>
>

> Hans,
> I looked at the picture of your UV exposure setup. I just wanted to
> comment
> that I would never use the round bulb. Use the florescent tubes and
> your
> results will be better. I have found that the round bulb tends to give
> more
> exposure in the center than at the outer edges. Even more apparent
> with
> larger boards. This is the reason all exposure units sold on the
> market use
> the florescent tube. You can compensate somewhat by having the bulb
> not so
> close, but this just increases your exposure time. The other bad thing
> about
> the round bulb is the heat. This will actually get in the way of your
> process, depending upon what type of photo etch you are using. I am
> trying
> to recall if it was a problem caused to the developer or if it was a
> consistency problem in the exposure. Nevertheless, I found it to be a
> problem several years back. If you modify your design to use the
> florescent
> bulbs, you will notice a marked difference in detail as well as less
> exposure time needed.
> -Mike
>
> ----- Original Message -----
> From: "Hans Wedemeyer" <hans@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Sunday, May 18, 2003 7:41 AM
> Subject: Re: [Homebrew_PCBs] How I make my PCBs
>
>
> > Leon,
> > good advice except for Easy-PC....
> > I spent full price on that program and found I wasted my money.
> > Here's what I think of Easy-PC
> > http://hans-w.com/ezpcbugs.html
> >
> > I moved on to EAGLE and have been happy with it. It's STABLE does
> not
> > blow up cause me to lose work=time=money.
> >
> > A limited version of EAGLE is available for Free, it is limited to
> two
> > sided board and size check it out at
> > http://www.cadsoftusa.com
> > EAGLE has a VAST library of part and users add parts all the time.
> > Compared EAGLE parts Library to to Easy-PC several 1000 to 1
> >
> > I put Easy-PC up for sale on eBay but none wanted it. In fact I put
> my
> > entire collection of Numberone product in the same auction
> > Filter program, Easy-PC for DOS and for Windows and the digital
> > simulator Pulsar. INo one reached my minimum Price of $200 ! It's
> still
> > here in a box onthe floor, I think I'll use the disks and CD's for
> > target practice sometime...
> >
> > Here's one thing that is not (was not)( they may have fixed it by
> now)
> > possible to do with Easy-PC for Wndows, in a situation where top and
>
> > bottom layers have parallel tracks sections that overlap, and a
> whole
> > bunch of closely spaced via's or other pads, it is not possible to
> put
> > the cursor on the trace/pad that I want for move/edit. It just snaps
> to
> > the nearest and of course that is not handy at all ! I can turn snap
> off
> > but that is not what it's all about.
> > EAGLE allows ANY pad/trace on any layer to be individually selected
> even
> > if they are overlapping.
> >
> > Pulsonix used to look like Easy-PC, I think they are the same
> bunch...
> > Although Pulsonix used to give the schematic editor away for free,
> the
> > PCB layout part is high $$$$ ! That's much like saying "this car is
>
> > free, but the special wheel cost $20,000 each "
> >
> > I'll get off my soap boix now...
> >
> > I make double side board all the time. I used to do it the way you
> > mentioned, and even wrote a program for my CNC mill to compensate
> for
> > alignment problems.
> > I found a better way by printing on transparencies and then aligning
>
> > them visually, then stapling them together. Then slide the board in
> > between the transparencies and sandwich the whole lot between two
> plates
> > of glass, and place the sandwich between two lamps
> > http://hans-w.com/setupforexposure.jpg
> > and
> > http://hans-w.com/twolampexposure.jpg
> > Credit for this sandwich idea goes to
> > http://www.electricstuff.co.uk/pcbs.html
> >
> > Alignment between top and bottom is good. Perhaps the greatest
> problem
> > I've run into is the HP LaserJet making different print sizes when I
>
> > mirror the one side.
> > I used to worry about getting the printed side of the transparency
> close
> > to the PCB, after testing with 5 mil lines I decided there is NO
> need to
> > mirror. Using the exposure as I how in my photo it allows me to do 5
> mil
> > lines all day everyday.
> >
> > Thanks for all the tips.
> > Best Regards
> > Hans Wedemeyer
> >
> >
> > Leon Heller wrote:
> >
> > > I've been making my own PCBs at home for about 40 years, starting
> by
> > > painting the pattern onto single-sided PCB material using a fine
> > > paintbrush and cellulose paint, with ferric chloride or ammonium
> > > persulphate etchant. I used 0.1" graph paper for designing the
> layout
> > > then marked the holes with a centre punch through the paper onto
> the
> > > copper surface. I even made a couple of double-sided PCBs using
> this
> > > technique, by masking off one side, etching the other side,
> drilling
> > > it,
> > > and using the drill holes as a guide when painting on the resist
> on
> > > the
> > > second side. I then masked off the first side with tape to etch
> the
> > > second side.
> > >
> > > When low-cost CAD software became available (I used Easy-PC from
> > > Number
> > > One Systems for years) I progressed to printing 2:1 artwork on a
> dot
> > > matrix printer. I then got a local litho platemaking company to
> > > produce
> > > a 1:1 positive transparency that I used with a home-made UV
> exposure
> > > unit and resist-coated PCB material. When I got an ink jet printer
> I
> > > found that I could get reasonable results by printing 1:1 artwork
> onto
> > >
> > > tracing paper.
> > >
> > > I now use an old LaserJet IIIp I picked up very cheaply to print
> 1:1
> > > onto LaserStar film and expose the PCBs in a home-made UV exposure
>
> > > unit.
> > > I sometimes use tracing paper (nice and cheap), but find that I
> get
> > > better results from the LaserStar film. The CAD software I use is
> > > Pulsonix, a professional package out of the same stable as
> Easy-PC. I
> > > regularly use 12/12 design rules, occasionally going down to 10
> mils
> > > if
> > > I need to route tracks between IC pads. Rather than conventional
> > > positive-resist FR4 PCB material, I usually use something called
> > > FPC-16
> > > which consists of a sandwich of compressed paper between thin
> layers
> > > of
> > > fibreglass. It's cheaper than FR4 and much easier to cut and
> drill.
> > > It's
> > > available from Mega Electronics, as is the LaserStar film.
> > >
> > > Etching is in ferric chloride. I place the etchant in a small
> plastic
> > > food container inside a larger container half-filled with hot
> water
> > > and
> > > continuously agitate the etchant manually by rocking the
> container.
> > > Etching typically takes 5-10 minutes.
> > >
> > > I'm quite pleased with the results. I intend to experiment with
> > > double-sided boards by making a UV exposure unit that can expose
> both
> > > sides of the PCB simultaneously. With a better printer and vacuum
> on
> > > the
> > > UV exposure unit I think I could get 8 mil tracks quite reliably.
> I've
> > >
> > > heard of other people managing it at home.
> > >
> > > Here is an example of one of my PCBs:
> > >
> > > http://www.geocities.com/leon_heller/pcb.html
> > >
> > > I often use the Pulsonix copper pour facility for this type of
> board,
> > > as
> > > it makes the routing easier. Cross-hatching is better with a laser
>
> > > printer, as they don't tend to print large black areas very well.
> > >
> > > Links:
> > >
> > > Mega Electronics: http://www.megaelect.demon.co.uk/
> > > Number One Systems: http://www.numberone.com/
> > > Pulsonix: http://www.pulsonix.com/
> > >
> > > Leon
> > > --
> > > Leon Heller, G1HSM
> > > leon_heller@...
> > > http://www.geocities.com/leon_heller
> > >
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> > >
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> > >
> > >
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> > [Non-text portions of this message have been removed]
> >
> >
> >
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> files:
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> >
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> >
> >
> >
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>
>
>
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>Mike,
>H'mm as I have pretty good looking boards and can do 5 mil all day long
>!
>
>Here's an example http://hans-w.com/pcb_harwin_rivets.jpg
>
>I've only been using Round Bulbs of various types for about 27
>years......
>I like the short exposure time and never have noticed the effect you
>menitoned, my largest board size
>is about 6"X7" and it exposed uniformly.
>
>Just what is it about my boards that you think would make them any
>better ? Please explain !
>
>Hans Wedemeyer
>
>
>Mike Putnam wrote:
>
>> Hans,
>> I looked at the picture of your UV exposure setup. I just wanted to
>> comment
>> that I would never use the round bulb. Use the florescent tubes and
>> your
>> results will be better. I have found that the round bulb tends to give
>> more
>> exposure in the center than at the outer edges. Even more apparent
>> with
>> larger boards. This is the reason all exposure units sold on the
>> market use
>> the florescent tube. You can compensate somewhat by having the bulb
>> not so
>> close, but this just increases your exposure time. The other bad thing
>> about
>> the round bulb is the heat. This will actually get in the way of your
>> process, depending upon what type of photo etch you are using. I am
>> trying
>> to recall if it was a problem caused to the developer or if it was a
>> consistency problem in the exposure. Nevertheless, I found it to be a
>> problem several years back. If you modify your design to use the
>> florescent
>> bulbs, you will notice a marked difference in detail as well as less
>> exposure time needed.
>> -Mike
>>
>> ----- Original Message -----
>> From: "Hans Wedemeyer" <hans@...>
>> To: <Homebrew_PCBs@yahoogroups.com>
>> Sent: Sunday, May 18, 2003 7:41 AM
>> Subject: Re: [Homebrew_PCBs] How I make my PCBs
>>
>>
>> > Leon,
>> > good advice except for Easy-PC....
>> > I spent full price on that program and found I wasted my money.
>> > Here's what I think of Easy-PC
>> > http://hans-w.com/ezpcbugs.html
>> >
>> > I moved on to EAGLE and have been happy with it. It's STABLE does
>> not
>> > blow up cause me to lose work=time=money.
>> >
>> > A limited version of EAGLE is available for Free, it is limited to
>> two
>> > sided board and size check it out at
>> > http://www.cadsoftusa.com
>> > EAGLE has a VAST library of part and users add parts all the time.
>> > Compared EAGLE parts Library to to Easy-PC several 1000 to 1
>> >
>> > I put Easy-PC up for sale on eBay but none wanted it. In fact I put
>> my
>> > entire collection of Numberone product in the same auction
>> > Filter program, Easy-PC for DOS and for Windows and the digital
>> > simulator Pulsar. INo one reached my minimum Price of $200 ! It's
>> still
>> > here in a box onthe floor, I think I'll use the disks and CD's for
>> > target practice sometime...
>> >
>> > Here's one thing that is not (was not)( they may have fixed it by
>> now)
>> > possible to do with Easy-PC for Wndows, in a situation where top and
>>
>> > bottom layers have parallel tracks sections that overlap, and a
>> whole
>> > bunch of closely spaced via's or other pads, it is not possible to
>> put
>> > the cursor on the trace/pad that I want for move/edit. It just snaps
>> to
>> > the nearest and of course that is not handy at all ! I can turn snap
>> off
>> > but that is not what it's all about.
>> > EAGLE allows ANY pad/trace on any layer to be individually selected
>> even
>> > if they are overlapping.
>> >
>> > Pulsonix used to look like Easy-PC, I think they are the same
>> bunch...
>> > Although Pulsonix used to give the schematic editor away for free,
>> the
>> > PCB layout part is high $$$$ ! That's much like saying "this car is
>>
>> > free, but the special wheel cost $20,000 each "
>> >
>> > I'll get off my soap boix now...
>> >
>> > I make double side board all the time. I used to do it the way you
>> > mentioned, and even wrote a program for my CNC mill to compensate
>> for
>> > alignment problems.
>> > I found a better way by printing on transparencies and then aligning
>>
>> > them visually, then stapling them together. Then slide the board in
>> > between the transparencies and sandwich the whole lot between two
>> plates
>> > of glass, and place the sandwich between two lamps
>> > http://hans-w.com/setupforexposure.jpg
>> > and
>> > http://hans-w.com/twolampexposure.jpg
>> > Credit for this sandwich idea goes to
>> > http://www.electricstuff.co.uk/pcbs.html
>> >
>> > Alignment between top and bottom is good. Perhaps the greatest
>> problem
>> > I've run into is the HP LaserJet making different print sizes when I
>>
>> > mirror the one side.
>> > I used to worry about getting the printed side of the transparency
>> close
>> > to the PCB, after testing with 5 mil lines I decided there is NO
>> need to
>> > mirror. Using the exposure as I how in my photo it allows me to do 5
>> mil
>> > lines all day everyday.
>> >
>> > Thanks for all the tips.
>> > Best Regards
>> > Hans Wedemeyer
>> >
>> >
>> > Leon Heller wrote:
>> >
>> > > I've been making my own PCBs at home for about 40 years, starting
>> by
>> > > painting the pattern onto single-sided PCB material using a fine
>> > > paintbrush and cellulose paint, with ferric chloride or ammonium
>> > > persulphate etchant. I used 0.1" graph paper for designing the
>> layout
>> > > then marked the holes with a centre punch through the paper onto
>> the
>> > > copper surface. I even made a couple of double-sided PCBs using
>> this
>> > > technique, by masking off one side, etching the other side,
>> drilling
>> > > it,
>> > > and using the drill holes as a guide when painting on the resist
>> on
>> > > the
>> > > second side. I then masked off the first side with tape to etch
>> the
>> > > second side.
>> > >
>> > > When low-cost CAD software became available (I used Easy-PC from
>> > > Number
>> > > One Systems for years) I progressed to printing 2:1 artwork on a
>> dot
>> > > matrix printer. I then got a local litho platemaking company to
>> > > produce
>> > > a 1:1 positive transparency that I used with a home-made UV
>> exposure
>> > > unit and resist-coated PCB material. When I got an ink jet printer
>> I
>> > > found that I could get reasonable results by printing 1:1 artwork
>> onto
>> > >
>> > > tracing paper.
>> > >
>> > > I now use an old LaserJet IIIp I picked up very cheaply to print
>> 1:1
>> > > onto LaserStar film and expose the PCBs in a home-made UV exposure
>>
>> > > unit.
>> > > I sometimes use tracing paper (nice and cheap), but find that I
>> get
>> > > better results from the LaserStar film. The CAD software I use is
>> > > Pulsonix, a professional package out of the same stable as
>> Easy-PC. I
>> > > regularly use 12/12 design rules, occasionally going down to 10
>> mils
>> > > if
>> > > I need to route tracks between IC pads. Rather than conventional
>> > > positive-resist FR4 PCB material, I usually use something called
>> > > FPC-16
>> > > which consists of a sandwich of compressed paper between thin
>> layers
>> > > of
>> > > fibreglass. It's cheaper than FR4 and much easier to cut and
>> drill.
>> > > It's
>> > > available from Mega Electronics, as is the LaserStar film.
>> > >
>> > > Etching is in ferric chloride. I place the etchant in a small
>> plastic
>> > > food container inside a larger container half-filled with hot
>> water
>> > > and
>> > > continuously agitate the etchant manually by rocking the
>> container.
>> > > Etching typically takes 5-10 minutes.
>> > >
>> > > I'm quite pleased with the results. I intend to experiment with
>> > > double-sided boards by making a UV exposure unit that can expose
>> both
>> > > sides of the PCB simultaneously. With a better printer and vacuum
>> on
>> > > the
>> > > UV exposure unit I think I could get 8 mil tracks quite reliably.
>> I've
>> > >
>> > > heard of other people managing it at home.
>> > >
>> > > Here is an example of one of my PCBs:
>> > >
>> > > http://www.geocities.com/leon_heller/pcb.html
>> > >
>> > > I often use the Pulsonix copper pour facility for this type of
>> board,
>> > > as
>> > > it makes the routing easier. Cross-hatching is better with a laser
>>
>> > > printer, as they don't tend to print large black areas very well.
>> > >
>> > > Links:
>> > >
>> > > Mega Electronics: http://www.megaelect.demon.co.uk/
>> > > Number One Systems: http://www.numberone.com/
>> > > Pulsonix: http://www.pulsonix.com/
>> > >
>> > > Leon
>> > > --
>> > > Leon Heller, G1HSM
>> > > leon_heller@...
>> > > http://www.geocities.com/leon_heller
>> > >
>> > > Yahoo! Groups Sponsor
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>> > [Non-text portions of this message have been removed]
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> ================

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> --- In Homebrew_PCBs@yahoogroups.com, "John Myszkowski"
> <myszka_us2000@y...> wrote:
> > I can shed some light on the bulb wavelength...
> >
> > All regular incadescent bulbs have very little UV generating
> ability.
> > [edited for brevity]
> >
> > Incadescent, Halogen bulbs do produce a high level of UV light.
> > [again edited for brevity]
> >
> > Fuorescent bulbs. These bulbs, when totally uncoated generate only
> > (Mostly) UV. Extremely little visible light is generated by the
> > fluorescent tube (when uncoated). The visible portion of light
> coming
> > from the fluorescent tube is generated by the fluorescence of the
> > various powders that coat the inner surface of the tube.
> > The wavelength generated by the tube (other than UV) is determined
> by
> > the composition of that powder.
> > ALL fluorescent bulbs generate UV, but the everyday bulbs sold for
> > home use have a powder coating that both blocks the UV as well as
> > generates only visible "white" light.
> > The power of these tubes is determined by the length and diameter of
>
> > the tube (plasma guide). Therefore, if the tube is the same length
> > and diameter as a normal 40Watt tube, then it is a 40Watt tube.
> >
> >
> > John M...
>
> John,
>
> Thanks for enlightening me! I find it almost amazing with such a clear
>
> disparity
> between the possible sources that I really haven't seen such a clear
> explanation until now.
>
> So my original question has a definitive answer: Get a fluorescent
> black light bulb. Period. End of discussion. It's easy to extrapolate
> from your discussion
> above that a BL or BLB fluorescent bulb is coated to filter the
> visible light and allow the UV-A through.
>
> I've found an interesting site in my continuing search for info. Of
> all places it's a Halloween haunted house type site. It talks about
> Black Light sources and has a pointer to what I would now consider the
>
> Holy Grail: compact fluorescent black lights. You can find it here:
>
>
> ttp://wolfstone.halloweenhost.com/TechBase/bltgen_BlacklightGeneration.html
>
> So unless someone has compelling evidence to the contrary, I plan to
> build my light box using a pair of 12 in BLB fluorescents which are
> easily found at the Home Depot or WalMart.
>
> Thanks for the help,
>
> BAJ
> > ================
>
>
> Yahoo! Groups Sponsor



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> Hans,
> I looked at the picture of your UV exposure setup. I just wanted to comment
> that I would never use the round bulb. Use the florescent tubes and your
> results will be better. I have found that the round bulb tends to give more
> exposure in the center than at the outer edges. Even more apparent with
> larger boards. This is the reason all exposure units sold on the market use
> the florescent tube. You can compensate somewhat by having the bulb not so
> close, but this just increases your exposure time. The other bad thing about
> the round bulb is the heat. This will actually get in the way of your
> process, depending upon what type of photo etch you are using. I am trying
> to recall if it was a problem caused to the developer or if it was a
> consistency problem in the exposure. Nevertheless, I found it to be a
> problem several years back. If you modify your design to use the florescent
> bulbs, you will notice a marked difference in detail as well as less
> exposure time needed.
> -Mike
>

> excellent still.

>
>
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>

>--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
><stefan_trethan@g...> wrote:
>
>> have all of you professional pcb drill presses or how do you drill
>your boards?
>> (maybe homebuilt ones and a picture of them???)
>>
>> regrinding drill bits (for pcb) should be possible with a small
>diamond wheel?
>> is this true / is this possible & good for one who can regrind a
>normal drill bit so that it works
>> again? i have no idea where to get a diamond grinding wheel, has
>anyone ideas?
>>
>> regards
>> stefan
>
>I use a dremel tool on a dremel drill press stand with used carbide
>drill bits (available at most hamfests, as well as All Electronics:
>
>http://www.allelectronics.com/cgi-bin/category.cgi?
>category=search&item=DRB-9&type=store
>
>This works extremely well for me.
>
>Jonathan
>
>

>Hello Stefan,
>
>18. May 2003, 21:20:47, you wrote:
>
>
> For EUR 75.00 you can make more than one exposure unit that I described
> in reply on one other post in this thread.
>
> 2 (two) UV-A fluorescent lamps made by Philips: EUR 5.00
> 2 (two) pairs of lamp holders with integrated starter holder: EUR 1.50
> 2 (two) 20W fluo ballasts: EUR 5.00
> Some wires for interconnecting, some MDF for box, mains cable,
> homebrew countown timer with PIC microcontroller: EUR 30.00
> =========
> TOTAL: EUR 41.50
>
> Don't hold me for all the prices that I've mentioned because I can not
> dig through all my sent messages where (on this forum) I gave all the
> prices for the stuff that I've bought.
>
>--
> Best Regards,
> Zoran
> mailto:zasto@...
> www.zas-elmed.co.yu
>
>
>

>
>
>I use a Minicraft drill and stand, similar to the Dremel units. It isn't
>very good - it's quite easy to break carbide drills. A friend of mine has a
>PCB dept. where he works and they have a rather old manual Excellon PCB
>drill. It looks as if it was originally *very* expensive and is *very*
>heavy. The drill comes up from underneath the PCB and a magnified image of
>the pad is shown on a screen. Someone at Southampton University was giving
>one of these away a few months ago, perhaps I should have taken it off his
>hands. 8-)
>
>Leon
>--
>Leon Heller, G1HSM Tel: +44 1424 423947
>Email:leon_heller@...
>My web page: http://www.geocities.com/leon_heller
>
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>

>
>----- Original Message -----
>From: "Stefan Trethan" <stefan_trethan@...>
>To: <Homebrew_PCBs@yahoogroups.com>
>Sent: Monday, May 19, 2003 8:39 AM
>Subject: Re: [Homebrew_PCBs] How I make my PCBs
>
>
>> i have also seen a setup where the drill came from underneath.
>> i have no idea how you cold see it with this unit.
>> but it looked not very expensive.
>>
>> wait.. now i remember also a very heavy press as you described standing in
>the pcb shop.
>> but it was VERY old.
>> it has had a round screen, it looked like some military target finding
>equipment.
>>
>> (i remember it looked like one of the alien/robot monsters in the old
>films with this "viewing screen"
>> as head and the legs of the very solid stand.)
>>
>> i have never seen anybody using this monster. they all prefered small
>white drill presses which more
>> looked like microscopes, without eyepieces.
>
>That sounds like it was the same thing. It's foot-operated, so both hands
>are free to position the PCB. A clamping lever comes down before the drill
>comes up, so the PCB is held securely. The magnification of the pad on the
>screen is quite high (it looks about 10 cm across), so it is quite easy to
>use, even if one doesn't have good eyesight.
>
>Leon
>--
>Leon Heller, G1HSM
>leon_heller@...
>http://www.geocities.com/leon_heller
>
>
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>
>