[time-nuts] Bye-Bye Crystals

Alan Melia alan.melia at btinternet.com
Mon Mar 13 17:59:30 EDT 2017

.....and some micro-soldering kit to attach the plated unit to the lead 
frame. Our factory used homemade hot air jets, I have no idea what the 
solder was prob LMP.

Lapping a single blank is difficult, one tends to get rounded edges(even 
with the best machine) which affect the activity. See the video, they are 
lapping several at the same time. The unplated blanks are put into a skelton 
holder and measured and the most promising one proceded with. First an 
evaporated contact to fix the blank to the lead frame. Then electrode 
evaporation which brings the frequency down, so the final stage evaporates 
electrode while measuring the mounted crystal frequency. Allowances need to 
be made for the can.

I doubt most small modern firms would have a X-ray goniometer (?) The one I 
saw in the 60s would never pass H&S criteria now. They probably buy cut 
blanks in bulk, I think they are relatively cheap this way. My supplier in 
the 90s did this.
The whole job is quite labour intensive, making a single crystal might 
easily eat $1000 worth of manhours for an amateur, not even allowing for the 
occasional "oops".
----- Original Message ----- 
From: "Attila Kinali" <attila at kinali.ch>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Monday, March 13, 2017 7:56 PM
Subject: Re: [time-nuts] Bye-Bye Crystals

> On Mon, 13 Mar 2017 15:01:39 +0000
> Adrian Godwin <artgodwin at gmail.com> wrote:
>> What minimal equipment would you need to make your own crystals ?
> The equipment is quite minimal:
> * A diamond precision saw to cut the crystals
> * Some tool to check the accuracy of the cut (orientation and thicknes)
> * a lapping/grinding machine
> * an electroplating machine (usually sputtering) for the electrodes.
> * either some machine to produce the crystal holder yourself or buy them
> * vacuum system to evacuate the crystal holder and to bake everything
> * something to (cold) weld the case close
> All of this can be put in a (relatively) small workshop.
> The difficulty is also not producing quartz crystals
> in holders. The difficulty controlling the whole process
> to such an degree that you get high quality crystals
> at the frequency you want.
> If you managed to do that, you can further improve
> your system by using a BVA[1,2] like geometry, where
> the electrodes are not on the resonator itself but
> on the surrounding crystal, which acts at the same
> time as holder.
> But be warned, many attempted to re-create the BVAs
> but few succeeded... and none but Oscilloquartz ever
> managed to produce a economically viable product.
> Attila Kinali
> [1] http://www.nature.com/articles/srep02132/figures/1
> [2] http://www.nature.com/articles/srep02132/figures/2
> -- 
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> the prosperity and technological sophistication in the world is of no
> use without that foundation.
>                 -- Miss Matheson, The Diamond Age, Neil Stephenson
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