John Curl's Blowtorch preamplifier part II - Page 4375 - diyAudio
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Old 1st October 2013, 04:23 PM   #43741
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Are there still any ASIC companies around? They're used to doing small runs.
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Old 1st October 2013, 04:45 PM   #43742
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Well, good luck Charles. If you are successful, you MIGHT be able to bypass ADI, which they kind of deserve, not giving you 'right of return' privileges anymore.
I had a similar problem with the Toshiba 2SK147, in 1990. They were drop shipping me 100 units/mo when this happened. They ALSO changed the recipe, and made a bad batch that was very noisy. The usual performance was shown by graphs on the data sheet, and they maintained it for more than a decade. In fact, it became almost a 'waste of time' to measure them on the QuanTech, before assembly, but then the 'process' changed and every device was different at 10 Hz. I still have a whole set of graded devices, picking the best ones for the input, next best for the second stage, and third best for an upgrade, still further down the line. Still, the worst case spec. was almost 10 times worse than was typical for the previous decade and HUNDREDS of devices didn't make even that spec, so I was allowed to return them for exchange stock. I am pretty sure that Toshiba was embarrassed about this, as later devices got better again. And so it goes! That is what we have to do, to make 'world class' audio products, right Charles?
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Old 1st October 2013, 06:46 PM   #43743
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Hi John,

It's like they say, "If it were easy, everybody would be doing it."

Charlie
Ayre
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Old 1st October 2013, 11:53 PM   #43744
Bonsai is offline Bonsai  Taiwan
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Quote:
Originally Posted by Mike Gergen View Post
Are there still any ASIC companies around? They're used to doing small runs.
Assembly usually handled by an independent sub con. That's totally different to a tech with a second hand machine.
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Old 2nd October 2013, 12:00 AM   #43745
Bonsai is offline Bonsai  Taiwan
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"I believe failures after burn in are no longer called "infant" mortality by definition. At the single digit production scale, burn in is pretty easy."

Perhaps in a strict definition, but the nightmare is failures on the customers production line and early failures in operational service life in the first few months.
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Old 2nd October 2013, 12:46 AM   #43746
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Quote:
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In this neck of the woods (NY), there were a few very small hybrid houses (10 employees or so) that I would think could do the work. You'd best discuss packaging with them prior to purchase, as well as die type. Bonding of the die can be epoxy, solder, gold/tin or gold/germanium.. Reflow either nitrogen furnace, scrubbing eutectic gold/silicon or ge, and sealing via epoxy, solder again, gold tin, or one shot welding. (one shot is just sooooo easy and quick) The hybrid house would need to have the equipment in house.
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We do chip on board, here in the lab about as DIY as you could ever want. Epoxy die attach and hand bonding that anyone could get the hang of. Gooped over with UV set goop, Masterbond has a new hermetic one that is quite good. I have no reason to believe there would be any reliability issues in a commercial grade (0-70C) environment.

We have also prototyped bare-die optical fiber connections with laser drilled alignment holes, at $35 a hole (2 required) it was not economical, but reliability was not bothered by this. The demo left a couple of customers with dropped jaws.
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Last edited by scott wurcer; 2nd October 2013 at 01:01 AM.
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Old 2nd October 2013, 12:48 AM   #43747
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Everybody, note: Nothing has been discussed of fixing the problem in the first place. '-)
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Old 2nd October 2013, 12:49 AM   #43748
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Given what I know about assembly, quality and reliability, I would not be recommending any of the proposals floating around here. Assembling semis is not something to be taken lightly.

For the record, my current employer assembles 70 billion devices a year and we have a problem when ppb hits 3 digits.
Come on this is the "highend" marginal reliability comes with the territory, it proves how close to the edge we are operating.
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Old 2nd October 2013, 12:55 AM   #43749
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Quote:
Originally Posted by scott wurcer View Post
Gooped over with UV set goop
There's your noise problem, it's UV rays knocking electrons out of bonds and the free radicals from the photoinitiator causing erratic charge carrier flow. You need virgin Teflon!

Keep at it, Scott, one day you'll get the hang of this IC stuff.
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Old 2nd October 2013, 01:28 AM   #43750
Bonsai is offline Bonsai  Taiwan
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"Come on this is the "highend" marginal reliability comes with the territory, it proves how close to the edge we are operating."

After paying 10 or 20 grand for high end gear I would want to know it would last.

Doing this stuff to demo is ok "engineering samples".

I have a few stories about bare die as well . . . But I'll not pursue that here.
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