Homebrew_PCBs

Greetings! Thanks to all you guys posting the valuable info!
I just wandered in here a few days ago, and was looking for some
helpful hints on starting out with homebrew PCBs. I have enjoyed the
posts here very much!

I'm the type of DIY person that believes in KISS (Keep it simple,
stupid), so I am using all locally available supplies. (except drill
bits and PCB stock that I ordered).
The methods I used are surely not optimal, but extremely simple and
readily available.
I just made my first successful PCB at home using the most basic
items and thought I'd share my limited experiences, and maybe get
some pointers (Especially on Etchant).

Drill:
My new but cheap drill press from Harbor Freight had so much wobble
in the chuck it snapped the .8 mm carbide drill immediately. Upon
inspection, I found the step pulleys were not bored properly,
causing the wobble.

I therefore needed a way to drill some boards with my Dremel. (I
don't have the drill-press stand attachment yet.)
I already knew that Carbide drills were very long-lasting, but
extremely brittle.
The slightest lateral movement or wobble will break these tiny
drills.
So I needed a way to improve my somewhat unsteady hand.
Here's what I found worked to steady the Dremel 395 enough to drill
with Carbide Drills.
I figured that taking the weight and alignment away from hand
control might help.
I'm a not-so-good guitarist, but I had a microphone stand with a
boom arm attached. (Any over-hanging support can be used. Light
fixture maybe?)

I suspended my Dremel from my boom by using 3 ordinary rubber-bands
such that it hung straight over my board and about an inch away.
The Dremel has a wire loop at the tail, so I just used it with a
half wrap around the cord to make it hang straight.
This allowed me to concentrate on a slight downward movement of the
tool using only 2 fingers with a very light touch.
This transfers the alignment and load of the tool to the Boom and
gravity.
I drilled about 60 holes using a .8 mm carbide resharpened bits from
Drill-Bit City http://shop.store.yahoo.com/drillcity/. (These bits
have a .125" shank and are reasonable price.)
I know that I will need a more reliable solution if I continue to
make boards, but I thought I'd pass on this temporary solution for
those that are just doing a few boards and don't want to invest in
more equipment.

Board: GC #21-243 1 oz. grade FR4 Positive Resist. Advertised as GC-
603 at Abra Electronics http://www.abra-electronics.com (I believe
that is a MG part number? Maybe they changed suppliers?)

Circuit Layout: Eagle w/12 mil traces.
I used Paint Shop Pro to Panelize these small 1" x 1" circuits, but
had to put the holes in manually, because my Eagle 4.03 didn't do
that when exporting the image. (It does it when printing direct,
though).

Transfer Method: Canon F80 Ink-Jet printer on Office Depot Ink-Jet
Transparencies.
Printed at 1200 dpi. 2 Passes on the same sheet to darken image.
Very clean looking results!
May try single pass later.

Exposure: Mid-day Texas direct sunlight.
Test exposure used 1" strip with foil "slider". Test was 30 sec. to
3 minutes in 30 sec intervals.
Results showed all (even 30 sec.) worked about the same, so I tried
one at about 35 sec. and one at 1 minute.
The 1 Minute board over-exposed I think, because I got some pitting
in the traces. The 35 sec. board came out pretty nice on the 12 mil
traces and would likely have done 5 mil if exposure was adjusted a
little better.
As soon as it arrives, I will be trying a surplus Derma-Spec lamp
($6.95) that has a small 6" Blacklight BLB tube and 1-Min. timer in
it. I ordered 2, and plan on modifying the 1 min. timer circuit to
suit the exposure time needed. Maybe this will offer a little more
control of the exposure.

Developer: Lewis Red Devil Lye purchased from Albertson's July,
2003. Mixed at approx 6g per Liter?
I calculated it to be 1 Tsp per Quart. Used Lowe's 1" foam brush
lightly. Worked great.

Etchant: I'm using 34% HCL from Lowe's Garden Center and 3% Hydrogen
Peroxide from Albertson's mixed 1:1.
I used no water, because most recipes call for stronger Peroxide.
This solution seems to work if you use it right away.
If you let it stand for a while it seems to be "die" or slow down.
Why is this?
I Really could use some input on this Etchant mix. Does the HCL/H2O2
mix always die soon after mixing?
Does it only work while the solution is still bubbling?

Other Supplies: 3 Cheap plastic freezer containers for
Developer/Etchant/Water. Homemade tongs fashioned from 2 plastic
forks.

Any input/comments would be much appreciated!
Regards to all,
Byron

See my "laptop drill press" in the photos section, and message 2057 in this group which describes it.

>As soon as it arrives, I will be trying a surplus Derma-Spec
> lamp ($6.95) that has a small 6" Blacklight BLB tube and
> 1-Min. timer in it. I ordered 2, and plan on modifying the 1
> min. timer circuit to suit the exposure time needed. Maybe
> this will offer a little more control of the exposure.

I did exactly that, and it works, sort of, but there were a few problems:

1. There is a transistor in there that gets very hot. Painting the heatsink black with a magic marker seemed to help some.

2. The lamp is pretty small, so it may not work very well, or be slow if you want to expose something bigger than 2 inches wide. It takes about 10 minutes to expose photosensitized boards from GC using this lamp from a distance of about 1 1/2 inches.

3. I believe that the amount of light that is put out changes as the lamp warms up. This may have been the cause of a different amount of exposure I seemed to have on a double sided board I made. There is an exposure meter circuit in the (highly recommended!) book The Art of Electronics by Horowitz and Hill, that might help.

A better solution might be to get a black light from a toy shop or party supplies store, for maybe $20-$30. I plan to try that next time I want to make a board. Warming the lamp for 10 minutes before making exposures might help make the exposures more consistent.

Cheers,
- Jan, fellow poor man :-)



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

>From: "starsnstripes_2003" <bwatson@...>
>Reply-To: Homebrew_PCBs@yahoogroups.com
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Poor Man's Drill Press
>Date: Sun, 20 Jul 2003 03:49:00 -0000

[deleted]

Congratulations!

>>
>Developer: Lewis Red Devil Lye purchased from Albertson's July,
>2003. Mixed at approx 6g per Liter?

I use about 10 g/litre. No brushing needed. It depends on the resist
material.

>I calculated it to be 1 Tsp per Quart. Used Lowe's 1" foam brush
>lightly. Worked great.
>
>Etchant: I'm using 34% HCL from Lowe's Garden Center and 3% Hydrogen
>Peroxide from Albertson's mixed 1:1.
>I used no water, because most recipes call for stronger Peroxide.
>This solution seems to work if you use it right away.
>If you let it stand for a while it seems to be "die" or slow down.
>Why is this?
>I Really could use some input on this Etchant mix. Does the HCL/H2O2
>mix always die soon after mixing?
>Does it only work while the solution is still bubbling?

Yes, the H2O2 gets converted to H2O and O2 very quickly. The reaction needs
the free oxygen to work properly. Keep adding H2O2 each time you do some
etching and you will eventually end up with a reasonable concentration of
cupric chloride. That will work without the H2O2, although you will have to
add a little from time to time, to convert the cuprous to cupric chloride.
You'll also need to add some HCl, occasionally. You'll need to heat the
cupric chloride for it to work - I use two containers, the outer one is
filled with hot water.


Leon
--
Leon Heller, G1HSM Tel: +44 1424 423947
Email:leon_heller@...
My web page: http://www.geocities.com/leon_heller

_________________________________________________________________
On the move? Get Hotmail on your mobile phone http://www.msn.co.uk/msnmobile

i also use hcl and h2o2.
the h2o2 is too cheap to bother with heating etc.

but be aware that strong bubbling is a sign of too much h2o2, then it is
too fast and may
attack weak resists.

i judge it by color.
if it is light green you are right with the concentration. it will work.
you can only see some very small bubbles and the board will take some
minutes.

if it turns from light green to dark green/brown (when shaking the
container gently normally)
you need some more h2o2, with 35% stuff and a small board only a few drops
are needed.


the problem:

after using the etchant the amount of h2o2 still in the solution causes it
to get light green.
when you fill it in a bottle and use it next time it is still light green.
but the speedup from the h2o2 is not there (it has disintegrated in the
meantime).
so you can either wait a longer time (until it gets dark green from normal
cucl etching) and add h2o2 then
or you can add a SMALL amount of h2o2 at the beginning.


i beg you not to make it "cooking". as the bubbles break up they spill a
lot of etchant around.
place some white paper over you will see.
also a lot of (clorine?) gas is produced, endangering your health.

further more h2o2 is simply used up (it is lost because it disappeares).


get yourself some 35% h2o2 at a chemicals shop. (maybe good drugstores have
it - here they have).
it is very cheap and you need MUCH less...

regards
stefan

Hi Byron,

It sounds like you are having a lot of fun!

I have used the sun to expose the photo resist on my boards for years ( since 1969 actually ) and I consistently get perfect boards with .010 traces between pins using a 30 second exposure time.

Lately I have been using tracing paper with a HP 5L with very good results. I have to tape it to a sheet of regular paper to get it to feed right but it is fast simple and much cheaper than transparencies.

Jack

----- Original Message -----
From: starsnstripes_2003
To: Homebrew_PCBs@yahoogroups.com
Sent: Saturday, July 19, 2003 8:49 PM
Subject: [Homebrew_PCBs] Poor Man's Drill Press


Greetings! Thanks to all you guys posting the valuable info!
I just wandered in here a few days ago, and was looking for some
helpful hints on starting out with homebrew PCBs. I have enjoyed the
posts here very much!

I'm the type of DIY person that believes in KISS (Keep it simple,
stupid), so I am using all locally available supplies. (except drill
bits and PCB stock that I ordered).
The methods I used are surely not optimal, but extremely simple and
readily available.
I just made my first successful PCB at home using the most basic
items and thought I'd share my limited experiences, and maybe get
some pointers (Especially on Etchant).

Drill:
My new but cheap drill press from Harbor Freight had so much wobble
in the chuck it snapped the .8 mm carbide drill immediately. Upon
inspection, I found the step pulleys were not bored properly,
causing the wobble.

I therefore needed a way to drill some boards with my Dremel. (I
don't have the drill-press stand attachment yet.)
I already knew that Carbide drills were very long-lasting, but
extremely brittle.
The slightest lateral movement or wobble will break these tiny
drills.
So I needed a way to improve my somewhat unsteady hand.
Here's what I found worked to steady the Dremel 395 enough to drill
with Carbide Drills.
I figured that taking the weight and alignment away from hand
control might help.
I'm a not-so-good guitarist, but I had a microphone stand with a
boom arm attached. (Any over-hanging support can be used. Light
fixture maybe?)

I suspended my Dremel from my boom by using 3 ordinary rubber-bands
such that it hung straight over my board and about an inch away.
The Dremel has a wire loop at the tail, so I just used it with a
half wrap around the cord to make it hang straight.
This allowed me to concentrate on a slight downward movement of the
tool using only 2 fingers with a very light touch.
This transfers the alignment and load of the tool to the Boom and
gravity.
I drilled about 60 holes using a .8 mm carbide resharpened bits from
Drill-Bit City http://shop.store.yahoo.com/drillcity/. (These bits
have a .125" shank and are reasonable price.)
I know that I will need a more reliable solution if I continue to
make boards, but I thought I'd pass on this temporary solution for
those that are just doing a few boards and don't want to invest in
more equipment.

Board: GC #21-243 1 oz. grade FR4 Positive Resist. Advertised as GC-
603 at Abra Electronics http://www.abra-electronics.com (I believe
that is a MG part number? Maybe they changed suppliers?)

Circuit Layout: Eagle w/12 mil traces.
I used Paint Shop Pro to Panelize these small 1" x 1" circuits, but
had to put the holes in manually, because my Eagle 4.03 didn't do
that when exporting the image. (It does it when printing direct,
though).

Transfer Method: Canon F80 Ink-Jet printer on Office Depot Ink-Jet
Transparencies.
Printed at 1200 dpi. 2 Passes on the same sheet to darken image.
Very clean looking results!
May try single pass later.

Exposure: Mid-day Texas direct sunlight.
Test exposure used 1" strip with foil "slider". Test was 30 sec. to
3 minutes in 30 sec intervals.
Results showed all (even 30 sec.) worked about the same, so I tried
one at about 35 sec. and one at 1 minute.
The 1 Minute board over-exposed I think, because I got some pitting
in the traces. The 35 sec. board came out pretty nice on the 12 mil
traces and would likely have done 5 mil if exposure was adjusted a
little better.
As soon as it arrives, I will be trying a surplus Derma-Spec lamp
($6.95) that has a small 6" Blacklight BLB tube and 1-Min. timer in
it. I ordered 2, and plan on modifying the 1 min. timer circuit to
suit the exposure time needed. Maybe this will offer a little more
control of the exposure.

Developer: Lewis Red Devil Lye purchased from Albertson's July,
2003. Mixed at approx 6g per Liter?
I calculated it to be 1 Tsp per Quart. Used Lowe's 1" foam brush
lightly. Worked great.

Etchant: I'm using 34% HCL from Lowe's Garden Center and 3% Hydrogen
Peroxide from Albertson's mixed 1:1.
I used no water, because most recipes call for stronger Peroxide.
This solution seems to work if you use it right away.
If you let it stand for a while it seems to be "die" or slow down.
Why is this?
I Really could use some input on this Etchant mix. Does the HCL/H2O2
mix always die soon after mixing?
Does it only work while the solution is still bubbling?

Other Supplies: 3 Cheap plastic freezer containers for
Developer/Etchant/Water. Homemade tongs fashioned from 2 plastic
forks.

Any input/comments would be much appreciated!
Regards to all,
Byron


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

Greetings,

As a make shift arrangement, how about placing a shank in the chuck of the
Harbor Freight drill press and mounting the Dremel to the shank thus
utilizing the down feed of the drill press for the Dremel.

Ned.

Stefan, Thanks for the ideas on H2O2.
My solution is still light green after 1 time use. I only saw some
light bubbling after mixing, and soon there were no bubbles.
I will try and locate the 35% Peroxide and add a few drops to re-
activate.

The other drilling and exposure ideas I have seen are very helpful!
The exposure with sunlight for 25-35 seconds may be the simplest,
but I'm not sure if clouds or season will affect results?
If exposure time varies, then I'll try the Derma-Spec to gain more
control (at the expense of speed).
I can add a heat sink? or even replace the whole ballast control
section easily (I hope).

I think the Dremel attached to HF drill press idea would be ok, but
the chuck/quill would need to be locked to prevent spinning? Or
still I must hold by hand.

I REALLY liked the elegant/simple Laptop Drill press that Jankok
posted in the photos section!
Thank You very much for sharing!

I will use that idea with the Dremel tool. It's just too easy to
make!
I want to try gravity feed w/adjustable stopper block and handle so
that I can actually rest the drill point on the hole for more
accurate positioning.
Maybe I need to add some counter-balance or spring to lighten the
weight of the tool?
If I do the woodwork carefully (to minimize play in the arm), Will
it work to rest the drill on the board before starting the motor
with a footswitch?.
This setup could be ideal for DIY board makers!

Thanks to everyone for their ideas! This is a fun hobby, and I have
learned quite a lot from your helpful posts!

Best Regards,
Byron

> if it turns from light green to dark green/brown (when shaking the
> container gently normally)
> you need some more h2o2, with 35% stuff and a small board only a

few drops

> are needed.
>
>
> the problem:
>
> after using the etchant the amount of h2o2 still in the solution

causes it

> to get light green.
> when you fill it in a bottle and use it next time it is still

light green.

> but the speedup from the h2o2 is not there (it has disintegrated

in the

> meantime).

<snip>

> get yourself some 35% h2o2 at a chemicals shop. (maybe good

drugstores have

> it - here they have).
> it is very cheap and you need MUCH less...
>
> regards
> stefan

> My new but cheap drill press from Harbor Freight had so much wobble
> in the chuck it snapped the .8 mm carbide drill immediately. Upon
> inspection, I found the step pulleys were not bored properly,
> causing the wobble.

If you check, the spindle is loose in the frame. HF is terrible as
far as fit goes.

Also the bearings are sloppy so even if you fix the loose spindle,
some of the runout will still be noticed.

The pulleys are so far removed from the spindle, I doubt you could
see any movement on the spindle regardless how much you moved them.

A quick test is to chuch up a drill and extend the spindle an inch or
so. put an indicator on it and just very lightly push and pull on
the drill. you will see a few thou movement with the slightest
pressure.

also, since the spindle is so loose, the rack and pinion pushes the
spindle towards the front of the machine as you increase pressure.

Having been the proud owner of more than 6 HF presses, I have some
little experiance with this 'problem'

Another simple 'fix' at least for IC's is to buy a machined carrier
and drill out all the posts, then drill one IC hole in the corner of
the chip and insert a pin or drill to locate that part and drill a
second hole thru one of the holes. insert another pin and you are
then aligned for the rest of the holes.

the biggest problem is that the soft brass will work for only a few
IC's before you need another.

Dave