Resistor distribution

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George Herold 13 years ago

I was killing some time last night before going to my first maker space meeting, watching some Dave videos.

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In the first video Dave finds that some Philips resistors have a ~

+/-0.5% distribution right around the ?correct? value.

In the second he finds that some cheaper (Xicon?) also have a 0.5% ?spread?, but the average is a bit (~0.35%) lower than nominal.

This raises a bunch of interesting questions. Do any resistor makers publish this sort of data? Does buying resistors from a ?better? manufacturer lead to resistors with a better mean. I use mostly cheap Xicon 1%ers. A few times I?ve gone hunting through the parts bin with an ohmmeter trying to find some particular value. Though I don?t have any data I did strike me that the average seemed a bit low. (When looking for a 10.0k ohm I found many more 9.9X k ohms than 10.0X k ohms.)

So does anyone know how 1% resistors are made? I find it hard to believe that they trim each one. (Do they trim the 0.1% ers?)

George H.

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John Larkin 13 years ago

Most 1% or better surface-mount resistors are laser trimmed. You can check them under magnification and see the trim cuts. If it's done very quickly, the mean could well be a bit off for any given reel.

Commodity thickfilms can cost under a penny each. I think - not sure - that 5% thickfilms are generally manufactured without trimming, so a batch of them could be a percent or two off.

We use the Susumu thinfilms for important stuff. They are very good, in tolerance, TC, and aging.

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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George Herold 13 years ago

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OK Thanks, I guess I can believe the trimming, but do they measure each one?

George H.

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.highlandtechnology.com jlarkin at highlandtechnology dot com

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Michael A. Terrell 13 years ago

them

could

I bought some Susumu thinfilms for under a buck a reel of 5000.

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Michael A. Terrell 13 years ago

How can they trim them if they don't?

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John Larkin 13 years ago

them

mean

Sure; they laser cut until the value is right. It's often an L cut; the cross axis is coarse trim, and the longitudinal cut is final fine trim.

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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John Larkin 13 years ago

them

mean

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Good deal. They are usually about 30 cents each.

John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

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George Herold 13 years ago

I could imagine that they measure a few to set the laser cut and then only do spot checks. But I clearly have no clue how it's done! It sorta blows my mind to think someone can make it, measure it, trim it, and then sell it to me for under a penny.

George H.

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George Herold 13 years ago

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ross

Well I scrapped the silk screen off the surface of a few and an L cut was exactly what I saw.

I think there is a Vishay resistor plant somewhere near me... I wonder if I could get a tour?

George H.

.highlandtechnology.com jlarkin at highlandtechnology dot com

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John Larkin 13 years ago

them

mean

A laser trimmer must be cool to see. The parts are flying through some handler/measuring gadget and being laser blasted at some number per second. Time matters, so there is probably some empirical second-guessing of subsequent thermal and other creep-back.

John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation

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Michael A. Terrell 13 years ago

All done by machines.

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Fred Bartoli 13 years ago

Selling too?

Thanks, Fred.

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Jeroen 13 years ago

Sort of: Droids.

Jeroen Belleman

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Michael A. Terrell 13 years ago

By computer? Yes. I haven't bought electronics parts in person or over the phone in over 20 years. :)

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Michael A. Terrell 13 years ago

Ann & all her fellow machines?

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krw 13 years ago

More like six to a penny.

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krw 13 years ago

Have you ever seen an operation like DigiKey? ...or Amazon? ...or NewEgg? Do you really think they have people chasing parts?

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Cydrome Leader 13 years ago

amazon sure has people doing the picking.

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Robert Baer 13 years ago

Back in the "good old daze" '70s to '90s) 5% carbon comps ran typically 2% high with a rather tight spread - maybe +/- 1% (to +/- 2% at most).

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krw 13 years ago

The video I saw was all automated.

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Resistor distribution

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