Hi! Is there any chemical substance capable of completely dissolving epoxy glass, 1.6 mm thick, but not dissolving at all the 35 uM copper that coats it? (it's a photoetched printed circuit board)
I'm trying to find a cheap way for making stencils.
Thanks! Antony
fire?
Remove "HeadFromButt", before replying by email.
Fire is good.
This is not easy. There is one solvent that dissolves epoxy, I forget its name, not common though.
Then you get the glass fibres everywhere.
This may not be the best approach.
You could try photoetching copper tape stuck on a simple plastic substrate.
3M make copper tape 4" wide by as long as you want. his would give you the capability to select a plastic which you can dissolve.Bill
IF all you want to do is make stencils, this is *not* the way to go. If the copper was etched into traces, what you will get are a lot of thin wiggles of copper that will not be related to each other; sheer stupidity. If not, then you get a thin, partly curled copper sheet; not brilliant as one can buy copper sheets of varying thickness - without the trouble. About 20 years ago or so, newsletters could be made by a typewriter on stencil material, which was wax covered paper mesh. Typing would push the wax away, thereby (in a Rex Rotary, Gestetner or other diplicating machine) allowing ink to seep thru and soak into the paper sheet (as the sheet passed thru the machine). One could also have electronic stencils (of drawings or photos) made. A similar technology still used today is the silk screen, which acts like a stencil. A silk fabric that is sheer enough to allow ink (or thick paint) be pressed thru is used; many coatings that are sensitive to light can be used to create the pattern. Developing the exposed pattern depends on the material used (even egg white and Potassium Dichromate as sensitizer can be used; warm water is the developer).
If you want to *copy* an existing PCB (ie: first make a negative for use in making others), then one can use a print frame to press the desired surface to a high contrast film (or other high contrast light sensitive material) and expose it to light. The light diffuses thru the PCB, and only very wide areas of copper on the non-contact side will cast shadows; all else will be rendered OK. This works quite well for one and 2-sided boards. Mulit-layer boards aer bitchy in that there may be shadowing from internal layers, but moer to the point, the inner layers cannot be recovered on an "as-is" basis.
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