DIP Socket leakage.

This is a follow-up on my leakage question from a week or so ago. I bought every DIP 8 pin socket on digikey and tested them with the Keithley 610B. Here's a pic, A connector string that ends in a Weidmuller terminal block.

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The terminal block shows leakage at about the 20 T ohm level when I breath on it. (1 T = 10^12) First a few notes: If let the 610 sit it shows a maximum resistance of about 50 T Ohm. (Perhaps things are a bit dirty inside?) Also at this very highest scale the time constant seems to be somewhere close to forever. I also worry a bit about my ability to drive this instrument correctly, changing scales (big knob and multiplier) gives kinda weird results as the resistance is changing. (The time constant seems tied to the multiplier knob and not the main one... I could read the manual I guess.) Finally the tests are a bit subjective, the leakage depends on how much I breath on it, and where I breathe. Anyway here are the results of minimum resistance I found when I breathed on the sockets.. Sockets listed by DK part number. Only one part from each batch was tested, with no attempt at cleaning.... whatever came out of the DK bag is what I used.

DK # manufactur CoO Resistance AE1001 Assman China 3 T ohm A400 Aries US 20 G ohm

1175-1467 CNC tech China 10 T ohm ED3013 On Shore tech China 3 T ohm 1212-1071 Preci-dip Swiss 3 G ohm A121607 TE conectiv. Swiss 10 G ohm 952-2209 Harwin UK 100 M ohm

The old Mill-Max sockets I had leak at the ~3T ohm level, so any of the Chinese made sockets will work for me. (The new Mill max leak at ~1 G ohm.)

George H.

Reply to
George Herold
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Yikes. 100 meg? That's really horrible. (Not that I believe they're really made in the UK, but anyway....)

Nylon really is awful stuff.

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
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Reply to
Phil Hobbs

How come it wants me to sign in to see your picture ?

Anyway, anything that is porous is probably bad if leakage in this range is an issue, and in fact you might want a dehumidifier. Why do you think stat ic electricity is not as much of a problem when the humidity is higher ? I think you are getting into that realm here, where on a warm humid muggy nas ty day you might just never get any reading above 50T.

And at those ranges, even little picofarads have really long time constants .

Reply to
jurb6006

I can't view the image. I just get a sign on screen. Do I have to sign up to view drop box images?

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Rick
Reply to
rickman

Hah, you're right I should have listed the material and not where they came from. I'll update it.

(Re: 100 Meg? yeah... hey I bought four I can send you some. :^)

Hmm seriously if there is anyone with a 610C that wanted to test seven IC sockets, (plastics) I'd ship the whole kit off to you, as long as you post the results here. (free shipping in the US only.) (Well OK Canada too... what's the shipping to Mexico?)

Keithley electrometer question, During breath testing I grab the ground on the electrometer, (front panel ground.. in case there is some difference?) So if I release my hand, then at the lower resistance settings I can wave my arms around and watch the needle respond, it's not too hard to peg it. But at highest settings this stops. Is that normal? (or what is the input resistance at 10^12 ohms?)

I was thinking I should order or beg one of JL's 1T resistors for calibration.

George H.

Reply to
George Herold

Really drop box wants you to sign in, Well they can't do it for nothing, I guess. There's not much to the pic, just my setup.

610B with adapter to bnc and then a double male BNC to a panel mount bnc female, that I soldered a weidmuller terminal block to.

I like the machined contacts in the weidmuller TB's BTW (Phoenix are nice too.)

George H.

Reply to
George Herold

I logged in with my account and your picture isn't visible.

Please setup a public folder and make the contents viewable by the GUM (great unwashed masses).

There should be a "Public" folder on your Home page. Inside the Public folder, you'll find the instructions as: "How to use the public folder.rtf" or use these instructions: or if you want to share an entire folder:

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Jeff Liebermann     jeffl@cruzio.com 
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Reply to
Jeff Liebermann

Ahh sorry,

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Does that work? George H.

Reply to
George Herold

Yep. Photo of a Kiethley 610B electrometer on the teraohms (10^12 ohms) scale.

If you're getting unstable readings, my guess(tm) would be humidity, RF interference, or bad breath.

I notice that you have a test socket for plugging in the sockets under test. Are you subtracting its resistance from the measured resistance? Also, are you protecting the test socket from your breath and greasy fingers?

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

No, I made every attempt to put my greasy fingers and bad breath everywhere... It could be the gorgonzola in the cobb salad I had for lunch.

All the sockets go to a high resistance if I don't breath on them.. (or if they are not in Singapore.)

George H. (oh and yes, the weidimuller TB leaked at ~20T ohm during the breath test, no subtraction was done... but the numbers are only good to a factor of 3 or 10... something like that... very fuzzy.)

Reply to
George Herold

If you like minimal material, you can make your own using discrete (single pin) sockets, either the flush mount kind (low profile!) or with pin tails (smaller pad = higher density or better routing). Mill-Max is the top brand with those.

Tim

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Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
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Reply to
Tim Williams

Link was updated in thread above

Reply to
K

What's with this breathing, I am missing something? Surely even the best insulator will appear leaky with a film of moisture. Aren't you testing your breathe not the insulator by doing this?

piglet

Reply to
piglet

Hydrophobic plastics such as PTFE and Kel-F don't readily form a continuous water film, but hydrophilic ones like nylon-66 suck water in like crazy, and their leakage is equally insane. That's one major reason that many packaged reed relays are so disappointing for high-Z work.

Cheers

Phil Hobbs

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Reply to
Phil Hobbs

nope here...

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updating table with body material.

DK # manufactur Resistance Body material AE1001 Assman 3 T ohm Polyester Thermoplastic A400 Aries 20 G ohm 4/6 Nylon Glass filled, Polyamide PA46

1175-1467 CNC tech 10 T ohm Polybutylene Terep.. (PBT) (or PPS) ED3013 On Shore tech 3 T ohm Glass Filled Polyester Thermoplastic, 1212-1071 Preci-dip 3 G ohm (PCT), Polyester, Glass Filled A121607 TE conectiv. 10 G ohm (PCT), Polyester 952-2209 Harwin 100 M ohm Plastic

Well the leakiest one is not nylon, but "plastic" whatever that is. The term polyester seems to be about as useful as plastic PBT looks nice,

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If it's good enough for George Jetson it's good enough for me. :^)

George H.

Reply to
George Herold

Yeah there is a socket that the material washes away in hot water.

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(it leaks at the 100 Meg ohm level with no breathe test.) I soldered it in and discovered that my pcb's can't pass the breathe test without some sort of cleaning. (Old Pcb's sitting in my drawer from previous projects, Kester 44 solder.)

George H.

Reply to
George Herold

"Available alternative" meaning whatever the water buffalos next door are putting out. ;)

Cheers

Phil Hobbs

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Dr Philip C D Hobbs 
Principal Consultant 
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Reply to
Phil Hobbs

The EU (and a few US states) have been restricting the use of certain plastic additives- specifically the class of brominated fire retardants. Electronic components need to meet flammability standards such as UL94 V-0 so they can't use raw resin.

I wonder if this is an unintended consequence of using an "available alternative" additive.

--sp

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Spehro Pefhany 
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Reply to
Spehro Pefhany

Hi piglet, well this all started with a leaky AD620 that is in an instrument in Singapore. After bashing my head against the wall for a few weeks, I asked here..

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(Does that link work.)

Which led me to the leaky socket.. I'm not 100% sure that it's the problem. But I'd give you 10:1 odds that it is. (There is not much else it can be.)

Anyway this led me to test moisture sensitivity by breathing on it. Not the best test.. but what else can I do? (for less than a few hundred dollars)

George H.

Reply to
George Herold

P.S. Along the line of griping about changes for environmental protection, we have the final report on crash last year of the Airbus operated by plucky little carrier Air Asia (I *really* like Air Asia):

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While the flight crew response was ultimately to blame, the sequence of events was started off by..

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The FAC FAULT was due to electrical interruption which was likely due 
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Reply to
Spehro Pefhany

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