Hi

Unfortunately ( at the rates you must use) the “blast it with a fire hose” approach
is not very fast…..

Bob

There is abrasive entrained in the fluid stream. Operation is in the ductile grinding regime so fluid pressures are around 6 bar or so, way below that used in abrasive water jet cutting.

It has been used to machine/polish crystal quartz waveplates and to machine/polish the surface of silicon wafers before uses for MEMS fabrication. Its even been used to carve channels in silicon wafers in such applications.

Bruce

In message 480971424.644410.1517715556849@webmail.xtra.co.nz, Bruce Griffiths
writes:

The images on this page gives a good impression about the current
skill-level in that area:

https://www.azonano.com/article.aspx?ArticleID=2740

I'm pretty sure that it is not the machine control but rather the
metrology that would be the challenge.

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

In message EE82321B-3176-4D0D-B0BC-64625DCE8627@n1k.org, Bob kb8tq writes:

So that brings me to another question:

We use quartz crystals in very simple geometries, usually cylinder
slabs, with very perfect surfaces - for all kinds of good and
sane reasons.

But mostly we use simple geometries because that is what we could
make work, with the pretty crude production mechanisms in second
world war.

On the other side of the business we have SAW resonators which uses
very complex conductor patterns on the surface to do their thing.

If we can/could etch quartz in precise complex patterns at will,
regardless of crystal orientation, sort of like the stuff we do in
silicon wafers already:

https://www.micralyne.com/fabrication-capabilities/etching/

Would that open up any interesting possibilities, or is the simple
cylinder slab by definition the best ?

--
Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG        | TCP/IP since RFC 956
FreeBSD committer      | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.

Hi

The gotcha is shown in the pictures. First point is that they are etching very
small features. A 5 MHz 3rd overtone blank is way thicker than what they are
playing with. The second issue is that even at small scale the walls are going
non-parallel. I seem to remember that you need straight walls on the cuts to
keep everything happy in terms of reflecting sound.

There is a lot of work done on odd shaped crystals. Your wrist watch has a
good example of that in it. It all comes down to what sort of process is required
to achieve the result. With the BVA the real answer is that you can do a mount
that achieves the same thing for a lot less money.

Either way, you are simply taking care of one plane (just like the SC). Forces
in the real world rarely are nice enough to only show up in one plane ….

Bob

Hi

Obviously you need two more 8607’s ….. :)

I suspect you are correct and the OCXO is doing better than the close in data suggests.

Bob

Here's a link to data on an 8607-008.  You may recognize the bottom plot
from a recent posting. :-)  But the ADEV and PN data at the top of the
page is from the factory test data.  The ADEV doesn't explicitly say so,
but I strongly believe it's based on comparison with a "gold standard" 8607.

http://febo.com/pages/oscillators/bva/

John

On 02/04/2018 02:38 PM, Bob kb8tq wrote:

On Sun, 4 Feb 2018 09:21:54 -0500
Bob kb8tq kb8tq@n1k.org wrote:

That's exactly the issue here. While SAW resonators benefit quite a lot
from the processing skills learned from semiconductor fabrication, these
skills do not translate into BAW manufacturing. SAW resonators are built
etching or depositing small features ontop of a SiO2 wafer that is supposed
to be as flat as possible. On the other hand BAW oscillators are 3D structures
by themselves. They are lens shaped (thus not flat) to keep the oscillation
energy trapped in the center of the slap, thus allowing the edges to be used
for mounting/contacting, with minimal damping of the oscillation.

Yes, the shapes are simple. But not only because that's the only shapes
we know how to build, but also because these shapes allow us to calculate
how the crystal will oscialate and because the simpler the structure the
easier it is to build it with high precision and accuracy.

It would be possible to use edging of surface structures into the
crystal to form a Bragg reflector (instead of the lense shape).
But I have no idea how well it works. Considering that it is easier
to build a slap that is flat and then etching structures on it, than
to form a 3D structure, I wonder why I have not read about anyone
doing exactly that (beside for SAW structures).

			Attila Kinali

--
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson

Hi

The typical quartz resonator is operating in a mode that involves
more than a surface wave. Much of the effort involves not just that
mode but getting rid of the vast number of similar modes that can
pop up. As you add structure complexity, you don’t just want to “improve”
the main mode. You also want to be sure you don’t encourage any
others …..

That all said, there are indeed people out there who do understand how
this all works. There aren’t a lot of them, but they are out there. From what
I’ve seen, the supply of “those who know” actually exceeds the industrial
demand for what they know. Like it or not, precision quartz resonators is
not a growth field.

Bob