Hello Jan,
Thank you for the marvelous idea! I have zero experience with this. If TI (who purchased National) will sell the bare die, then I have two questions:
1) Do you think that they could attach a bond wire even though there may not be any feature on the die to do so? I always thought that the die had to have a gold pad or similar to attach the bond wire to...
2) Who are some of the smaller companies that would encapsulate a run of a few thousand dice? (US-based ideally.)
Kind regards,
Charles Hansen
Ayre Acoustics, Inc.
Hello Jan,
Thank you for the marvelous idea! I have zero experience with this. If TI (who purchased National) will sell the bare die, then I have two questions:
1) Do you think that they could attach a bond wire even though there may not be any feature on the die to do so? I always thought that the die had to have a gold pad or similar to attach the bond wire to...
2) Who are some of the smaller companies that would encapsulate a run of a few thousand dice? (US-based ideally.)
Kind regards,
Charles Hansen
Ayre Acoustics, Inc.
Hi Charles,
Normally any manufacturer will sell you bare dies, pretty cheap even as most of the cost seems to be in the packaging these days.
Yes you need something to attache that bond wire to, that may be a problem (not for the '844 of course). Perhaps Scott can enlighten us.
I'll see if I can find that outfit, it was indeed US based.
Edit: Norsk Engineering at Santa Barbara. The attached was one of the things we considered, a dual AD844. A dual CCII allows some attractive circuits that you used to be able to do with the Maxim MAX435, 436 iirc, sort of balanced CCII, very linear because you can cancel some of the current non-linearities.
Jan
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Hello Jan,
Thank you for the marvelous idea! I have zero experience with this. If TI (who purchased National) will sell the bare die, then I have two questions:
1) Do you think that they could attach a bond wire even though there may not be any feature on the die to do so? I always thought that the die had to have a gold pad or similar to attach the bond wire to...
2) Who are some of the smaller companies that would encapsulate a run of a few thousand dice? (US-based ideally.)
Kind regards,
Charles Hansen
Ayre Acoustics, Inc.
The equipment is available second hand for a lot less than you might think, and you could find someone easily to train a tech. You could buy wafers probed, inked, and scribed onto a stretched piece of thermo-plastic film or die in carriers. Those nice gold plated prototype headers are readily available with as many leads as you could need. I'm still looking for the QuanTech schematics I forgot my packup for remodeling.
Another point, the QuanTech has limited use as an engineering diagnostic tool. It does not find the corner frequency of 1/f or actually separate G-R noise from the 1/f.
The idea that someone sits in front of a QuanTech sorting amplifiers one by one is quaint, but it did happen the usual 40 years ago just like these stories. Op-amps cost up to $75 each then.
EDIT - Yes it is unlikely that a pad would be available except on the AD844.
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To continue,
Jan and Charles I would recommend something more like these Side-Brazed Dual In-Line Ceramic Package - SBDIP - SemiPKG(????) - Semiconductor Ceramic Packages, Metal Packages, Plastic Packages, Packaging Materials, Lids and Covers, Connectors, BURN-IN and Test Sockets, Distributor in China/Asia. they come with a lid and solder preform and need only a "pizza" oven to seal them. PDIP's need far more complicated injection molder.
First hit a fully automated ball bonder $3500 used and you probably already have a solder reflow setup that could have a profile programmed to seal PDIP's. Used and Reconditioned Bonders for sale!
If you want bragging rights to full audiophile quality all gold assembly this would be the way to go.
Jan and Charles I would recommend something more like these Side-Brazed Dual In-Line Ceramic Package - SBDIP - SemiPKG(????) - Semiconductor Ceramic Packages, Metal Packages, Plastic Packages, Packaging Materials, Lids and Covers, Connectors, BURN-IN and Test Sockets, Distributor in China/Asia. they come with a lid and solder preform and need only a "pizza" oven to seal them. PDIP's need far more complicated injection molder.
First hit a fully automated ball bonder $3500 used and you probably already have a solder reflow setup that could have a profile programmed to seal PDIP's. Used and Reconditioned Bonders for sale!
If you want bragging rights to full audiophile quality all gold assembly this would be the way to go.
Wow! What an expensive solution. Still, it has merit.
Now let me explain what I presume Charles has to do to test the ADI IC's for noise, today.
First, the supply voltages are pre-adjusted, so they don't have to be reset.
Once the IC is put in its test socket, the test board is reinserted and the test door is closed, turning on the power supplies. Initially, there is a test position with a test tone, so that you can get exactly the closed loop IC voltage gain that corresponds with the test meters. There are 5 test meters, all damped, and with spot noise frequencies of:
10Hz, 100Hz, 1KHz, 10KHz, 100KHz. They all measure at the same time, giving and array of 5 measurements. The experienced eye can see the 'ideal' noise, and with the rise in the 10Hz and 100Hz meters, the amount and generally the break-point frequency in the 1/f noise. It isn't like we can personally control the 1/f in any case, so knowing the precise 3dB point isn't very useful.
So after a few seconds for the meters to settle down, you get an indication if THIS particular IC meets your requirements or not. For comparison tests, you don't have to write anything down, just reject the extra noisy ones.
Then you open the test gate and replace the IC with another one.
While this may seem to be a crude and old fashioned test to some, it works pretty good for initial development AND quality control, even today.
Now let me explain what I presume Charles has to do to test the ADI IC's for noise, today.
First, the supply voltages are pre-adjusted, so they don't have to be reset.
Once the IC is put in its test socket, the test board is reinserted and the test door is closed, turning on the power supplies. Initially, there is a test position with a test tone, so that you can get exactly the closed loop IC voltage gain that corresponds with the test meters. There are 5 test meters, all damped, and with spot noise frequencies of:
10Hz, 100Hz, 1KHz, 10KHz, 100KHz. They all measure at the same time, giving and array of 5 measurements. The experienced eye can see the 'ideal' noise, and with the rise in the 10Hz and 100Hz meters, the amount and generally the break-point frequency in the 1/f noise. It isn't like we can personally control the 1/f in any case, so knowing the precise 3dB point isn't very useful.
So after a few seconds for the meters to settle down, you get an indication if THIS particular IC meets your requirements or not. For comparison tests, you don't have to write anything down, just reject the extra noisy ones.
Then you open the test gate and replace the IC with another one.
While this may seem to be a crude and old fashioned test to some, it works pretty good for initial development AND quality control, even today.
Yes the shiny gold definitely has something going for it!
But I am no longer interested in this - I realised that I would be able to make a technically good product but marketing is my weakest side so I let it slide.
I was just pointing out to Charles the possibility to go diy all the way, as it were.
Jan
Hello Scott,
Thanks for the outstanding information. I have one dumb question. All of the PDIP packages I have seen use a tinned pure copper leads (except for through-hole LEDs). All of the metal (or glass) packages I have seen use copperweld leads. Presumably there is a reason for this. Would it be possible to use pure copper leads with the SBDIP?
Thanks,
Charles Hansen
Ayre Acoustics, Inc.
Sorry, you are beyond my expertese. I'm sure you understand that there are probably reliability and other manufacturing issues behind these choices.
Hello Scott,
Thanks for the reply. It's a bit of a puzzle to me. All of the "hermetically sealed" packages use the copperweld. A good example is the plain old TO-3. When I look at where the pin comes out, it appears that the seal between the pin and the body is a small bead of glass.
But it can't be that the glass won't bond to copper, as there is copper on the outside of the copperweld (plus tin these days and solder in the old days). Also, I never saw any, but for a while I am told that Krell had a custom version of a Motorola TO-3 output device that used a nickel (?) plated copper body rather than the normal nickel (?) plated steel body. I don't know if they had copperweld leads or pure copper leads, but it just adds to the evidence that it is possible to mix and match the materials but just isn't done for reasons that are beyond me.
Perhaps they have decided that people who want the extra-reliability of a hermetically sealed package also want the extra reliability (physical strength) of the copperweld leads....
Anybody else have any ideas on this one? Or for that matter, why copperweld is used on epoxy packaged through-hole LEDs?
Thanks,
Charles Hansen
Ayre Acoustics, Inc.
Thanks for the reply. It's a bit of a puzzle to me. All of the "hermetically sealed" packages use the copperweld. A good example is the plain old TO-3. When I look at where the pin comes out, it appears that the seal between the pin and the body is a small bead of glass.
But it can't be that the glass won't bond to copper, as there is copper on the outside of the copperweld (plus tin these days and solder in the old days). Also, I never saw any, but for a while I am told that Krell had a custom version of a Motorola TO-3 output device that used a nickel (?) plated copper body rather than the normal nickel (?) plated steel body. I don't know if they had copperweld leads or pure copper leads, but it just adds to the evidence that it is possible to mix and match the materials but just isn't done for reasons that are beyond me.
Perhaps they have decided that people who want the extra-reliability of a hermetically sealed package also want the extra reliability (physical strength) of the copperweld leads....
Anybody else have any ideas on this one? Or for that matter, why copperweld is used on epoxy packaged through-hole LEDs?
Thanks,
Charles Hansen
Ayre Acoustics, Inc.
I suspect the move to RoHS is a key driver in leadframe materials. The ceramic packages are specialized low volume stuff for hi-rel applications (read military) where RoHS is not an issue. Copperweld is stronger but I thought most of those packages used Kovar (which is also magnetic).
A quick web search found this link KYOCERA | Semiconductor Parts | Contract Assembly | Flip Chip to a vendor for the ceramic packages who offers assembly services in San Diego. They also offer lids with RF absorbers to control microwave resonances in the package.
Mark Brasfield got NS to package some of their parts in cans and swore that it was an audible improvement. Even the irascible Mr. Pease admitted hearing a difference. Mark, and the entire team at National that was doing the audio stuff have been booted since TI took over. You may be able to contract him to assist in getting the ideal IC solution packaged for you.
A quick web search found this link KYOCERA | Semiconductor Parts | Contract Assembly | Flip Chip to a vendor for the ceramic packages who offers assembly services in San Diego. They also offer lids with RF absorbers to control microwave resonances in the package.
Mark Brasfield got NS to package some of their parts in cans and swore that it was an audible improvement. Even the irascible Mr. Pease admitted hearing a difference. Mark, and the entire team at National that was doing the audio stuff have been booted since TI took over. You may be able to contract him to assist in getting the ideal IC solution packaged for you.
The lead material and the package material and the temperatures used to make all need to be thermally compatible (amoungst other things). The thermal coefficient of expansion of the various materials must be maintained closely or the part will 'crack' under temp changes/variations. Thus, the lead material and the seal and body material you see used.
Thx-RNmarsh
Thx-RNmarsh
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Sorry All!
I just check with a magnet and was not aware of Kovar. Some materials puzzle me as they are only slightly magnetic. One needs to use a strong NeFeB magnet to get even a slight pull. These were SMT "specialty polymer" caps from Kemet. Maybe the nickel barrier layer was thick enough to attract???
If anybody has contact info for Mark Brasfield, please PM me or you can e-mail me at first initial last name at ayre dot com.
If he had just connected pin 5 like the AD844 (designed by Barrie Gilbert in the early '90s!), it would be much more versatile. TI is selling them for less than half the price of the ADI part, the specs are a bit better, and they may not have the noise problem that the ADI parts have had for the last decade since they switched the wafer size...
Best regards,
Charles Hansen
Ayre Acoustics, Inc.
I just check with a magnet and was not aware of Kovar. Some materials puzzle me as they are only slightly magnetic. One needs to use a strong NeFeB magnet to get even a slight pull. These were SMT "specialty polymer" caps from Kemet. Maybe the nickel barrier layer was thick enough to attract???
If anybody has contact info for Mark Brasfield, please PM me or you can e-mail me at first initial last name at ayre dot com.
If he had just connected pin 5 like the AD844 (designed by Barrie Gilbert in the early '90s!), it would be much more versatile. TI is selling them for less than half the price of the ADI part, the specs are a bit better, and they may not have the noise problem that the ADI parts have had for the last decade since they switched the wafer size...
Best regards,
Charles Hansen
Ayre Acoustics, Inc.
a.wayne, nanotubes are too much for this thread to bear. '-) Of course, that is where the 'advanced' physics is, but they keep to old textbooks around here.
The very hint that nanotubes could be used for anything in the audio realm, has been disdained for years, by the usual critics.
Actually, I find nanotubes quite an interesting subject, but most of their properties will be either ignored or denied by many here.
The very hint that nanotubes could be used for anything in the audio realm, has been disdained for years, by the usual critics.
Actually, I find nanotubes quite an interesting subject, but most of their properties will be either ignored or denied by many here.
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Nice one, John. It appears to be referenced frequently by other researchers, which I would take as a good sign ...
This is in the realm of non-linear behaviour, which is where all the action is in terms of achieving high quality, vs. technically competent, sound. A little movement beyond always seeing everything in terms of extremely well behaved, highly predictable RLC characteristics is always a worthwhile detour ...
This is in the realm of non-linear behaviour, which is where all the action is in terms of achieving high quality, vs. technically competent, sound. A little movement beyond always seeing everything in terms of extremely well behaved, highly predictable RLC characteristics is always a worthwhile detour ...
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