Re: Printed Circuit Board Supplies

At 10:38 PM 2/9/00 -0600, you wrote:

>From: hansw <hansw@...>
>
>Ted,
>A question comes to mind. As you have a laminator to look at, how

difficult do you think it would be to make one ?

Take a metal plate, flood it with IR flood lights, Set the board on it and
let it come up to temp, I dont remember the temp, but 90 to 120 F sounds
about right. Lay the precut film on it and crank it through an old washing
machine wringer. The commercial usits have heated rollers coated with a
high durometer coat. You could use a length of pvc tubing. HEating the
rollers is hard, and yoiu would still be better off heating the platen (the
metal plate leading to the rollers.)

>Then there is the question of cost of dry film. What are the minimum these

(whoever you use ) will sell for in $... how much

>film would that be ?

Too much.

>What's the shelf life of the film ? this would be important for me...

A year as I remember it, but if you keep it cool and dark, three years is
reasonable.

Consider silk screening, It is cheap, easy and you can get the stuff,
advice, and even training in any medium sized town with a graphic arts
store or a junior college. Again, it is much cheaper than photoimaging
becuase any graphic arts store will sell you a cheap wooden framed silk
screen and image it with your circuit for cheap. Tape both sides side by
side so one screen screns both sides of the board. You flip it and screen
the other side. As suggested, You drill two i/8 inch holes kittycorner
and tape down a couple of registration pins (cheap) so the board registers
easily on the other side when you flip it.

Screening ink will dry by itself in a few days, or you can dry it on the
lowest level of heat in your kitchen oven with a small fan blowing air
through it. A fan from an old pc power supply will move plenty of air.
Prop the oven door open an inch or two.

>One thing I like about positive pre sensitized boards, I simply use Red

Devil Lye as a developer and it's fast. Exposure for 1

>minute under my UV light source and develop in Lye for about 30-45

seconds... I make transparencies on my LaserJet, I'm also

>able to consistently get very fine lines <10 mill is not problem, anything

seems pointless for my kind of work.

>
>Hans Wedemeyer
>
>