HI > On Feb 18, 2021, at 8:06 PM, Lux, Jim <[email protected]> wrote: > > On 2/18/21 4:38 PM, Bob kb8tq wrote: >> Hi >> >> Ok >> >>> On Feb 18, 2021, at 6:40 PM, Magnus Danielson <[email protected]> wrote: >>> >>> Hi, >>> >>> A lot of fascinating steps. It would be real fun if one would do a >>> coarse in which one would actually build a handful of crystals oneself, >>> to learn the basics, and measure them up. It would be a fun >>> summer-coarse to do. >> A crystal plant isn’t going to let you in to do this. The risk of breaking >> gear / >> stopping production isn’t going to work for them. >> >> So what do you need to come up with for the group?: >> >> You need some quartz bars. Forget about trying to grow them yourself unless >> you have the ability to deal with battleship guns …. >> >> Next you will need an x-ray setup for the angles you wish to deal with. For >> AT >> cuts that may not be to bad. For SC’s … good luck at < $500K. >> >> For a summer camp sort of setup, go with a diamond saw, dice up the blank >> slowly, >> but with cheap gear. >> >> Now you need lapping equipment. Normally this is a device made from >> cast iron and with “couple of meters in each direction” sort of dimensions. >> Not much of an alternative out there so a fairly unique thing to find. >> >> Rounding the blanks can be done a couple of ways, a fairly normal lathe >> might be adapted to do this. >> >> For the contour process, I’d just go with drum processing. I’ll take you a >> couple of months, but there isn’t a lot of fancy gear involved. >> >> Chemical etch is easy, but you need to do it. >> (note that “polish” got left out …. ) >> >> Now you need to put the base plate on the blank after cleaning it. It’s >> a thin film deposition process. If you are set up to make semiconductor >> wafers, you likely have the gear to do it. Same sort of deal, masks, >> mounting fixtures, thickness monitoring, gold evaporation at very >> high vacuum. >> >> Next up drop it in a solder seal base and solder it into an enclosure. >> (note that finish plate got left out). >> >> You now have a working device. >> >> Bob >> > If you want RF resonators to build in a "simple lab", it's probably easier to > do SAW devices on a blank you buy. Then it's a single layer of aluminum that > you photo etch. Not hugely different than PC boards or a thick film hybrid. > > Getting small feature sizes might be a challenge - when we did it where i > used to work, they did photo reduction onto a photoresist covered substrate. > I wonder if someone has a laser rig that could programmed to "draw" the > pattern on the resist at the right scale. As I recall, 50 MHz has a > wavelength of about 60 microns, and your transducer fingers are half > wavelength apart. You're probably not going to scribe those with an X-acto > knife by hand. But it's not particularly exotic. > > We bought the substrates already plated, but that is something you can > conceivably do in a small lab - vacuum system and evaporation rig. > > Then you have to bond wires onto the aluminum. But that's a "available from > surplus" thing - and if you are equipped for doing hybrids you're all set.
You can (and companies often do) buy blanks “in the round”. They already are properly oriented (x-rayed). They have the basic shaping already done. You still need to do the final shaping / polishing / cleaning / plating etc. Getting the metal to properly attach to quartz is a bit exciting. More so with some metals (gold) than with others (chrome). One often sees a very thing under layer of chrome on gold plated crystals. Bob > > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
