While in college I got a container of HF from our chemistry lab. It came in a plastic container as it would eat glass. I did etch numerous crystals with it. While I was not aware of the hazards, I did use some caution in using the stuff. 73 – Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ 07731
848-245-9115
Hi Dennis:
My reading of patent 2479286 is that after grinding, quartz crystals have micro cracks that propagate with aging and temperature cycling. By using an HF etch the cracks are removed thus stabilizing the crystal for both aging and temperature (See Fig 6, 7 & 8 in patent). The patent also includes a slide rule design (Fig 10) which, for a given frequency change and cut, tells you the etch time.
PS I worked in microwave semiconductors and they used HF. Extremely dangerous stuff since it attacks humans in such a way that they are not aware of it.
--
Have Fun,
Brooke Clarke
axioms:
1. The extent to which you can fix or improve something will be limited by how well you understand how it works.
2. Everybody, with no exceptions, holds false beliefs.
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