Gene Heskett wrote: > On Wednesday 26 December 2007, Dave Engvall wrote: > >>Hi Jon, >> >>Riston sounds like better stuff and easier to use. I think one gets >>sharper etching if the etchant is pumped over the foil. > > > Many years ago, we had a DEA spray etcher at the tv station where I got > started back in the early 60's. You could write notes in the 10x10 boxes of > the gfx background we used to do our layouts on, and which got reduced 4x > before the board was exposed. With that etcher, it was a 3 to 5 minute job > as it sprayed both sides of the board at the same time, and you could still > read the notes very clearly in the copper when done. I have never rocked a > pyrex cake pan and got anywhere near that sort of precision results since. > Right, I built my own spray etcher years ago, with a pump machined all out of Plexiglas. I used a DC motor on top, which had a vertical shaft down through the etchant to drive the pump, so there were no rotating seals. I discovered that FeCl2 would turn nylon screws brittle with a 2 minute exposure and the heads would start popping off! it had a lot of problems, mostly getting the etchant hot. I eventually pulled a complete and working Kepro spray etcher out of the dumpster at work. Just one little dab of JB Weld on a leaky spot and it works beautifully. it has a heater in a Titanium tube in the bottom. I put a couple bricks in it to reduce the volume of etchant required to fill the sump.
Jon ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
