Printed circuit board fabrication

fredbloggstwo wrote:
Hi Tony

there is quite a good article here about making the parts for short
production runs of PCBs

http://www.electricstuff.co.uk/pcbs.html

You can also get the required parts and chemicals from he

http://www.megauk.com/

With regards to the software, there are several low-cost packages you
can buy. If you are local to Maplins (I assume that you are in the
UK and not in the colonies as one of this newsgroup's contributors
is) there is a neat little software package called PCB Wizard which
costs around £30 or so and does most functions and has some
libraries, auto routing etc.
So it might cost you about £100 of so to set it up, assuming that you
have a good quality printer, but its also good fun and you will never
use Veroboard again :-)

Cheers

Mike

Thanks Mike,

Closest Maplins is in Shrewsbury, about an hour away, but Maplins online
delivery service is pretty good.

I've been looking at the open source package http://www.freepcb.com/ but it
seems too advanced for my needs. It would take me longer to enter a netlist
and learn how to use this app than simply drawing a layout in a paint
program. Maybe PCB Wizard is more user friendly. Just drag/drop from a
component pallet then drag tracks around to connect stuff. That would be
plenty for me.

Thanks for the links, great article !

On Fri, 6 Feb 2009 18:24:37 -0000, "TonyL"
wrote:

Arny Krueger wrote:
"TonyL" wrote in message
...

One way is to make a transparency and use that to mask a board
coated with an emulsion then exposed to UV and develop. Then etch
in the normal way.


That looks the most likely option for me.

UV boxes start at around 70 UKP, though. Surely they are just boxes
with UV bulbs and maybe a timer. Any reason I can't make my own box
and buy a replacement UV bulb or two ?

Isn't the old light-sensitive resist still around?


I've never seen that. I would imagine handling while keeping it out of the
light would be inconvenient.

Radiospares used to do UV sensitive double sided board. It was covered
with black plastic, which you could use as a resist if you fancied
just cutting the pattern with a scalpel. No idea if they still stock
it.

d
--
Pearce Consulting
http://www.pearce.uk.com

On Fri, 06 Feb 2009 18:51:36 GMT, (Don Pearce)
wrote:

On Fri, 6 Feb 2009 18:24:37 -0000, "TonyL"
wrote:

Arny Krueger wrote:
"TonyL" wrote in message
...

One way is to make a transparency and use that to mask a board
coated with an emulsion then exposed to UV and develop. Then etch
in the normal way.


That looks the most likely option for me.

UV boxes start at around 70 UKP, though. Surely they are just boxes
with UV bulbs and maybe a timer. Any reason I can't make my own box
and buy a replacement UV bulb or two ?

Isn't the old light-sensitive resist still around?


I've never seen that. I would imagine handling while keeping it out of the
light would be inconvenient.

Radiospares used to do UV sensitive double sided board. It was covered
with black plastic, which you could use as a resist if you fancied
just cutting the pattern with a scalpel. No idea if they still stock
it.


Just checked - they do.

d

"Don Pearce" wrote in message
...
On Fri, 6 Feb 2009 18:24:37 -0000, "TonyL"
wrote:

Arny Krueger wrote:
"TonyL" wrote in message
...

One way is to make a transparency and use that to mask a board
coated with an emulsion then exposed to UV and develop. Then etch
in the normal way.


That looks the most likely option for me.

UV boxes start at around 70 UKP, though. Surely they are just boxes
with UV bulbs and maybe a timer. Any reason I can't make my own box
and buy a replacement UV bulb or two ?

Isn't the old light-sensitive resist still around?


I've never seen that. I would imagine handling while keeping it out of the
light would be inconvenient.

It wasn't all that sensitive.

Radiospares used to do UV sensitive double sided board. It was covered
with black plastic, which you could use as a resist if you fancied
just cutting the pattern with a scalpel. No idea if they still stock
it.

Seems like UV is the more modern approach. Plenty of that around as long as
the Sun is shining.

In article ,
Arny Krueger wrote:

"TonyL" wrote in message
...

One way is to make a transparency and use that to mask a board coated
with an emulsion then exposed to UV and develop. Then etch in the
normal way.


That looks the most likely option for me.

UV boxes start at around 70 UKP, though. Surely they are just boxes with
UV bulbs and maybe a timer. Any reason I can't make my own box and buy a
replacement UV bulb or two ?

Isn't the old light-sensitive resist still around?

Also, direct sunlight is loaded with UV.

You do need to use a reasonably accurate combination of level and time
though - like any exposure. And the coated board is rather expensive to
experiment with.

--
*Why is it considered necessary to screw down the lid of a coffin?

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

You do need to use a reasonably accurate combination of level and time
though - like any exposure. And the coated board is rather expensive
to experiment with.


I would guess for calibration....a timer and a 1 cm by 10 cm strip of coated
board with sections exposed for various time periods.

"TonyL" wrote in message
...
Dave Plowman (News) wrote:

You do need to use a reasonably accurate combination of level and time
though - like any exposure. And the coated board is rather expensive
to experiment with.


I would guess for calibration....a timer and a 1 cm by 10 cm strip of
coated board with sections exposed for various time periods.


Not a lot of use with sunshine, as the UV content varies from
minute-to-minute depending on cloud cover.

David.

In article ,
TonyL wrote:
I've been looking at the open source package http://www.freepcb.com/ but
it seems too advanced for my needs. It would take me longer to enter a
netlist and learn how to use this app than simply drawing a layout in a
paint program. Maybe PCB Wizard is more user friendly. Just drag/drop
from a component pallet then drag tracks around to connect stuff. That
would be plenty for me.

It's one reason I still use RISC OS. The Draw prog on that with a small
library of basic pad layouts is all that's needed for simple stuff. Same
for drawing circuit diagrams. But then I quite enjoy figuring out layouts
and best track routes. IMHO it takes too long to learn a CAD one to be
worth it unless you're using it frequently.

--
*Modulation in all things *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
TonyL wrote:
You do need to use a reasonably accurate combination of level and time
though - like any exposure. And the coated board is rather expensive
to experiment with.


I would guess for calibration....a timer and a 1 cm by 10 cm strip of
coated board with sections exposed for various time periods.

Yes - with a light box which I have. But with the sun it would vary
according to time of day and year - even on a cloudless day?

IIRC, some ovens with exposed elements can be used too.

--
*It's o.k. to laugh during sexŒ.Œ.just don't point!

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Arny Krueger wrote:

"TonyL" wrote in message
...

One way is to make a transparency and use that to mask a board coated
with an emulsion then exposed to UV and develop. Then etch in the
normal way.

That looks the most likely option for me.

UV boxes start at around 70 UKP, though. Surely they are just boxes
with
UV bulbs and maybe a timer. Any reason I can't make my own box and buy
a
replacement UV bulb or two ?

Isn't the old light-sensitive resist still around?

Also, direct sunlight is loaded with UV.


You do need to use a reasonably accurate combination of level and time
though - like any exposure.

Not like *any* exposure. The "negative" generally is line art, thick black
over transparent film. Very, very high contrast. The "film" is designed to
be very tolerant of small exposures to light. It wants to produce a high
contrast "picture".

And the coated board is rather expensive to experiment with.

With the old stuff, I never ever missed the first time. After you do this a
bit, you end up with scraps to play with.