I enjoyed the work, so it wasn't really work. It was play, getting paid a small stipend to diddle with somebody else's (very expensive) toys. I'm fascinated with how things work and manufacturing processes, so the lab I taught was big cool. If we had stayed in Florida I'd probably still be teaching it. I was working on my masters and working full-time for Fedex also, so I was pretty busy.
We started our students with blank, lightly-doped wafers and we manually went through all the processes to create both MOSFETS and BJT's. The goal was that every student fabricated working transistors; no I-V transistor curves, no pass. If you kept a close watch on them so they didn't screw up too badly, it was never really a problem. Despite the hazards (temperature and chemical), I never had any accidents on my watch (came close once or twice), and I had several students come to me and say it was the coolest class they ever took, so I must have been doing something right. I do miss that lab.
The student ASME chapter had a basic little machine shop in an outbuilding on campus maybe a mile from the engineering building. I knew the guy who ran it and I had keys, so I used to go there between classes as an undergrad when I was stuck on campus for a few hours and it wasn't worth going home, and I was free to work on my own projects there. Machining for me was/is great stress relief. I helped them out with some of the fabrication of one of the cars for inter-collgiate competition (mini-baja):
http://www.knightsracing.cecs.ucf.edu/baja.html
They had just completed a formula car and won the novice category when we left the area. They had tried to farm me to design an engine-management system, but I was really busy with school and my wife was paying all the bills, so I didn't feel right about taking focus off school to do that. IIRC, the ASME members were almost exclusively mechanicals; I don't remember ever seeing another electrical in the gang.
Jim
-----Original Message-----
From: Druid Noibn
Sent: Jul 21, 2011 2:23 PM
To: gingery_machines@yahoogroups.com
Subject: Re: [gingery_machines] ZA-12 scraping
Hi Jim,
Good information - thanks.
I'm a little familiar with the activities (a few decades in electronics and a couple of other engineering fields) and in a previous life the company I worked at produced wafer handlers.
A few ideas come to mind noting the setup and DOD (they really got in the way with some optical research colleagues were doing).
Sounds like a lot of fun albeit work.
Take care,DBN
--- On Thu, 7/21/11, Jim Ash <ashcan@earthlink.net> wrote:
From: Jim Ash <ashcan@earthlink.net>
Subject: Re: [gingery_machines] ZA-12 scraping
To: gingery_machines@yahoogroups.com
Date: Thursday, July 21, 2011, 1:32 PM
This professor was big into the electrical properties of materials. He sponsored a number of grad students in this stuff, and he was also in charge of the white room where I taught the semiconductor fabrication lab. A lot of his work centered around SAW filters.
They were testing specific crystalline wafers. IIRC, he contracted a guy who grew crystals to grow some with some new exotic material. Then he sent the raw crystals to somebody who cuts them (kinda like the people who facet diamonds) to be y-cut, which was an unusual cut that had the attention of the DOD. The wafers were circular and very thin, very delicate. The base of the fixture was cylindrical with a shallow-bored cavity in one end to closely fit a wafer, and a circular pattern of screw holes around it on that same surface. The top part was a mating cylinder with a special transducer screwed into it (like a spark plug) that would lightly contact the wafer when the fixture was closed up. When closed up, the crystal was electrically isolated inside this copper cave (except for a small area around the transducer); the ultimate Faraday's cage.
My understanding was that they clamped the base to a serious ground and hooked the transducer to a network analyzer to get the frequency response of each crystal. I never actually saw the setup in action, only the results.
Jim
-----Original Message-----
From: Druid Noibn
Sent: Jul 21, 2011 12:26 PM
To: gingery_machines@yahoogroups.com
Subject: Re: [gingery_machines] ZA-12 scraping
Hi Jim,
Working is copper is a bear - it is easy to understand why you would like to avoid it.
Out of curiosity - what was the item for?
Kind regards,DBN
--- On Thu, 7/21/11, Jim Ash <ashcan@earthlink.net> wrote:
From: Jim Ash <ashcan@earthlink.net>
Subject: Re: [gingery_machines] ZA-12 scraping
To: gingery_machines@yahoogroups.com
Date: Thursday, July 21, 2011, 9:26 AM
I machined some research lab fixtures for a professor in copper. He supplied the material, and I think it was pure. It was small precise work, including tapping a half-dozen 4-40 holes an inch deep. I got the job done, but it was a mess to machine. I always wonder now when I pick up a new material. If the ZA-12 works like that, I don't want any part of it and I'll stuck to AL.
Jim
-----Original Message-----
From: Rick Sparber
Sent: Jul 21, 2011 9:16 AM
To: "gingery_machines@yahoogroups.com"
Subject: Re: [gingery_machines] ZA-12 scraping
Jim,
I recently machined some ZA but don't know if it was -12. It was rather tough stuff. Nothing like extruded aluminum which can be gummy. The machining did not remind me of cast iron and the surface finish was a bit rough. The chips were small. I did not get any curls.
Rick
Rick.Sparber.org
On Jul 21, 2011, at 6:07 AM, Jim Ash <ashcan@earthlink.net> wrote:
> Since the subject of ZA-12 came up, you guys have peaked my curiousity and I'd like to try brewing some and playing with it. I've only ever poured aluminum (unless lead, solder, and Wood's metal count), but I'm interested in the improvement of mechanical properties of the ZA-12 over the Al. The one question that I haven't seen answered is if scraping the ZA-12 is any easier or harder than Al. I presume the ZA-12 is easy to machine, but then again, I've never tried it.
>
> Jim Ash
>
>
> ------------------------------------
>
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