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T. O. metal can electrical test rejects

metaL ken

Oct 5, 2011
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Good day to all:

I'm new here.
I just want to ask what could be the cause of our electrical test rejects for T. O. metal cans.
The test in particular is dark current. Id=10 nA max.. I tried using a newer spool of gold wire (expires on a later date) against the ones that will expire on an earlier date but i still got the same result. Our operator said we're getting higher values and sometimes the pico ammeter reads out "overflow". Can someone help me on this?

Thanks in advance!
 

shrtrnd

Jan 15, 2010
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What is the device.
And are you talking about hermetically sealed metal can packages as opposed to DIP's?
(Did you check your data sheets carefully?)
 

metaL ken

Oct 5, 2011
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yes sir. it's for hermetically sealed metal can packages. basing from our customer's web site (eGTRAN), the assembled metal cans go to their products for optoelectronic applications.
 

Digital_Angel_316

Oct 1, 2011
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Good day to all:

I'm new here.
I just want to ask what could be the cause of our electrical test rejects for T. O. metal cans.
The test in particular is dark current. Id=10 nA max.. I tried using a newer spool of gold wire (expires on a later date) against the ones that will expire on an earlier date but i still got the same result. Our operator said we're getting higher values and sometimes the pico ammeter reads out "overflow". Can someone help me on this?

Thanks in advance!

Is this a recurring problem or one you are having with just one run/ batch?
What are the process variables? Check all calibrations and procedures to start.
Did something change on the line, particularly relative to your last good run?
Bonding, stray parametrics, materials, and processes?

I would expect there must be standard review procedures for out of tolerance items check them, if not, institute them.
Tell us more about the Process Steps, consider the key parameters.
 

shrtrnd

Jan 15, 2010
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I still don't see enough information to give a coherent opinion.
My experience with 'dark current' involved photomultipliers.
We used a deuterium lamp souce, through a chemical reaction in gas, to read the
luminance via a photomultiplier. In the application we had, often the life of the photo-
multiplier was reduced if it came from the manufacturer with a very low 'dark current'
spec to begin with. We often rejected photomulipliers that did not meet our needs,
even though they met the manufacturer's specification.
If you're working expensive photo devices, EACH device should have it's own spec.
You'd be able to narrow your parameter needs, by running tests on both ends of the
specs for the devices.
If your device is some generic mass-produced run with only general specifications,
you'll have to deal with the entire range of the parameter for 'dark current'.
Since I don't have enough info, this may not be helpful, but I'll speculate:
If this is a new test, maybe somebody didn't check the specs compared to the device you have.
If you've been running this device for a long time, and all of the sudden you're having a
problem, you may have changed suppliers for some device in your circuit that is not
meeting your previous requirements.
If you've been running this device for a long time, and all of the sudden you're having a
problem, maybe you just received a batch of devices that just aren't up to spec.
Again, I recommend at least supplying us with information on the part number of the
device (unless this is some one-of-a-kind, special built device).
I think we can help with suggestions (at least), if you can share detailed information.
 

metaL ken

Oct 5, 2011
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Good day to all:

The device is PD300-001-105. And it is a recurring problem. I only found PD300-003-105 from the anadigics website. (eGTRAN is formerly anadigics.) I'm new to the company. According to them they have assembled PD300-003-105, but only as a qual lot. For whatever reason, they discontinued it. What we're assembling up to the present is PD300-001-105. Again, according to them, the problem existed before (up to now), despite of changes in materials used. There was a change in capillary to address non-sticking bond issues.

Thank you very much!

I'll try to post the process flow later as well as other parameters.
 

shrtrnd

Jan 15, 2010
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What is the composition of the new capillary?
Are you experiencing a chemical reaction with your process media and the new capillary?
 

metaL ken

Oct 5, 2011
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Good day to all:

Some additional info.. The PD300-001-105 photodiode is InGaAs. Caps are from Schott.
The caps supplied by our customer is shiny throughout. No special coating of some sort to blacken the inner part of the caps.
Question: Are there caps that have a different coating on the inside. Different from the outside?
 

metaL ken

Oct 5, 2011
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Also, our operators bond 5 to 10 units and test it for dark current before proceeding with the whole lot. So far, the readings passed. The next process would be third optical inspection, third optical inspection gate, pre-seal bake, capping / welding, helium bombing, fine leak test, gross leak test, and then the dark current test.
 

metaL ken

Oct 5, 2011
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Here is our process flow for our PD300-001-105.
1. 2nd Optical Inspection
2. 2nd Optical Gate
3. Die Attach
4. Die Alignment
- + / - 3 mils (x-y axis)
5. Die Attach Epoxy Cure
- Temp.: 100 deg. Celsius
- Time: 1 hr.
6. Wire Bond
7. 3rd Optical Inspection
8. 3rd Optical Gate
9. Helium Bombing
- 4 hrs. + 15 min. @ 40 - 45 psi
10. Fine Leak Test
- 5 x 10-7 atm-cc/sec min.
11. Gross Leak Test
- Galden DO2
- 125 + / - 10 deg. Celsius
12. Dark Current Test
- Supply: 5 V
- Id: 10 nA max.
...
 

metaL ken

Oct 5, 2011
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And our capillary is from peco. I can't find more info. though, except that it's made from ceramic (compact ceramic).
 

shrtrnd

Jan 15, 2010
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Some manufacturer's use the black coating on the caps, some don't. It doesn't interfere with the chemical reaction.
Any possibility the curing of the epoxy is discoloring the epoxy, causing you problems?
Any possibility of wiring bonding (typically high voltage, similar to arc welding), affecting
the cured epoxy, causing a problem?
I hope you're making damned sure the photodiode is not attached to the assembly
when you're wire bonding. The high voltage arc of the wire bonding can damage
your photodiode.
If your people ARE using stitch-wire type high voltage wire-bonding, consider a different
method of wire-bonding.
Protect your photodiode.
 

metaL ken

Oct 5, 2011
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Good day sir:

I'll try to evaluate some units using our KNS wedge bonder. I've checked our UTC 100's manual for its spark voltage. It's - 2150 V.
 

shrtrnd

Jan 15, 2010
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I'm mention one other problem I saw once using epoxy to set a photo device:
One type of epoxy we used cured leaving a gaseous 'cloud', which left a film on the
photo device's lens. May not be an issue, but something else I thought of to be
aware of.
A secondary consideration for installing your photo diode, depending on your application
(not a good idea if vibration is an issue,) would be to wire-bond a device SOCKET into
your circuit, and install the photo diode into the socket, eliminating electrical or heating
stresses on the photo device itself.
Just a couple other ideas to consider.
 
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