Steve
Have you thought about starting a dbase list. It would be good to
have Toms offer where it was easily found.
Garry
--- In Homebrew_PCBs@yahoogroups.com, "twb8899" <twb8899@y...> wrote:
> Brian and the group,
>
> I spent over twenty years in the circuit board business and
probably
> tried every method that came along. The most difficult part for the
> hobby board producer seems to be good artwork generation and
etching.
> With this in mind you might want to spend some of your money on a
> used process camera for making negatives.
>
> Most circuit board films are now made with photoplotters and this
has
> put many of these cameras on the used equipment market not to
mention
> the ones that were thrown in the dump. If you print your designs
with
> a laser or inkjet printer at 2:1 scale and photograph it at 50% on
> the camera a very accurate film negative can be produced. A film
made
> this way will not have the print density problems that arise when
> trying to expose through paper artwork from printers and plotters.
>
> Dry film photoresist is one of the best ways to sensitize the
copper
> panel. This film is put on the panel with a roll laminator but I
have
> had excellent results by gently laying it on the clean copper
surface
> and using a clothes iron to heat the resist for proper adhesion to
> the copper. A small glass contact printing frame can be purchased
at
> most camera or photographic supply stores. This contact frame will
> give the proper contact between the negative film and the photo
> resist. A sunlamp works good as a UV exposure source.
>
> Developing of the exposed resist can be performed in a small tray
of
> 1% sodium carbonate (soda ash). I have also used Tide laundry soap
as
> a developer but it seems to take a bit longer.
>
> Ferric chloride is a good etchant for hobby boards. It will last
for
> a long time and can be used in a tray, bubble, or spray etcher.
> Other etchants are available but many of them have a limited tank
> life. Ferric chloride does not have this problem and is stable for
a
> long time, just heat it up and start etching.
>
> A small high speed drill press with carbide bits will do a good job
> for making the holes. KBC Toools sells a small drill press like
this
> for less than $150. I have one of these and I like it much better
> than any of the Dremel drills. The Dremel Tool drills have way too
> much spindle runout and their drill press stand is very flimsy.
>
> I only make circuit boards for the instruments that I produce and
no
> longer make boards as a merchant shop. When I got out of the
> commercial business I kept just enough equipment to perform the
> processes discussed in this message.
>
> The following equipment is what I'm using for my board production:
>
> CAD system
> Photoplotter
> Vertical camera
> Template (stylus) drills
> Pin router
> Small spray etcher
> Various silk screening equipment
>
> Some of this equipment can be built in the home shop or picked up
at
> auctions or on eBay.
>
> Concerning photoplotters, I saw a table top photoplotter just like
> the one I use on eBay. This was about a year ago and it never got
one
> bid! This unit could have been picked up for less than $500 and it
> would have been a bargain. This type of plotter makes the whole
> process very easy so it would be a wise move to latch onto one of
> these units.
>
> If anyone is interested, I would be willing to make photo plots for
a
> nominal price. The plot data would have to be supplied as a Gerber
> plot file with aperture list or file. The films would be made on
> Kodak 7 Mil film with a negative or positive image. Email me off
list
> if there is any interest in this.
>
> Tom