Adam and the group,
If you want to make plated through boards you should consider asking
a board fabricator to sell you some of their existing chemistry. The
cost of this stuff is higher than you would think because of the
minimum quantities that must be purchased when starting new. These
chemical baths require almost daily testing and replenishment with
the main culprit being the catalyst and electroless copper baths.
Some systems don't require an electroless copper bath and use a super
activated palladium catalyst which is a little easier to maintain.
After taking on something like this you should just go into the
business and get as much work as you can to make it worth doing. One
thing to consider is that 15 years ago there were about 3000 shops in
the USA and earlier today while I was talking with a drilling machine
supplier he said there were less than 200 shops left in the USA. Many
of the big guys from earlier years all went broke.
On one hand there is a glut of used equipment available really cheap
right now which means you can setup a shop without much cash. For
example, when I closed my PWB plant I sold my best Excellon drilling
and routing machine for $6500. This machine was in excellent shape
and cost $146,000 new. One of your biggest expenses will be just
MOVING all of this equipment and setting it in place.
On the other hand the business climate in the PWB industry is soft
with mucho foreign competition so its a tough call on what to do. It
is a fascinating technical business but there isn't much money in it
anymore. Printed circuits are a commodity now days with low selling
prices.
One thing to consider is trying to find some small plating tanks for
your electrolytic plating and do the through hole sensitizing using
pyrex trays on hot plates. This will work on a small scale. A small
spray etcher with sodium persulfate will handle the etching part. If
you wanted reflowed solder you could modify a donut fryer to get it
up to 475 degrees F and you would be all set to reflow the tin/lead
plating.
The rectifier for acid copper plating should be capable of at least
30 amps per square foot per side. The solder plating requires
somewhat less current at around 20 amps per square foot. If you use a
CAM program to setup your films they will tell you the total square
inches of copper traces and pads for plating.
When I closed my plant I kept one photoplotter for making precision
films,a smaller drilling machine, pin router and silk screening
equipment. Now I just make boards for the instruments and control
systems that I make. Everything is single sided except for one RF
board with only four through holes which I bond with eyelets. There
are times when I miss the plated through capabilities but I manage
without it and doing fine.
If anyone wants more information on how the plated through process
works I would be glad to write up something on it. I did it for
twenty four years and learned it from the ground up.
Tom
--- In
Homebrew_PCBs@yahoogroups.com, adam Seychell
<adam_seychell@y...> wrote:
> Hi all,
> I was just wondering how many people here would like to make
their own
> plated through hole double sided boards. How far are hobbyists
willing
> to go ? The main question is if this extra step is worth the amount
of
> chemicals and equipment needed to make plated through. I had the
desire
> to make plated boards for a long time but only because I find both
the
> chemistry and electronics side interesting. From what I have found
with
> experiments, is that the process can be done at home if you are
prepared
> to put in the effort. There is a lot setting up with the equipment
such
> as plating tanks, etching tanks, making holes conductive, applying
dry
> film photoresists and then there is the equipment for analyzing the
> chemistry, not to mention the learning curve. About the only good
news
> is that the chemistry is relatively low cost and the toxicity is
about
> the same as conventional copper etching solutions (copper is a
toxic
> heavy metal). The ultimate aim would be 4 layer boards, but that
raises
> a whole new set of hurdles.
>
> reagrds,
>
> Adam