Author Topic: Most stable VPG parts, HZ or VHP?  (Read 9389 times)

0 Members and 1 Guest are viewing this topic.

Offline kj7e

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: us
  • Damon Stewart
Most stable VPG parts, HZ or VHP?
« on: June 10, 2018, 03:31:18 pm »
I'm aware you have to read between the lines with VPG datasheets and the real world performance may differ from the implied specs.  When comparing the VPG HZ vs VHP which tend to have the lowest real world TCR and Self Life stability?  Curious if anyone has any real experience between them.  I know the HZ series is used on some secondary resistance standards, but it almost seems as if the VHP101,VHP103,VHP203 may perform even better (at least looking at the datasheets).  The advantage of the HZ parts seems to be higher power with larger packages using multiple elements and the option for 4 wire leads.  Maybe the multiple elements in the VHAxZ series (eg VHA518-10Z) could be an advantage and offer some additional averaging to stabilize the overall part?  Thoughts or experience?

 
The following users thanked this post: 3roomlab

Offline TiN

  • Super Contributor
  • ***
  • Posts: 4370
  • Country: us
  • PPM Alert!
    • xDevs.com
Re: Most stable VPG parts, HZ or VHP?
« Reply #1 on: June 10, 2018, 05:39:45 pm »
I like my two VHA518's. Price of those is also VERY different to VHP1xx/2xx :) Both of VHA518's I tested and published in my TCR database article before.
YouTube | Metrology IRC Chat room | Let's share T&M documentation? Upload! No upload limits for firmwares, photos, files.
 
The following users thanked this post: kj7e

Offline kj7e

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: us
  • Damon Stewart
Re: Most stable VPG parts, HZ or VHP?
« Reply #2 on: June 10, 2018, 08:30:40 pm »
Thanks Illya, I just read over your TC article.  It seems the VHP101's you tested all showed a slightly better TC than the VHA518's. Just for fun, I'm going to call Texas Components tomorrow and get a quote for a few options.
 

Online splin

  • Frequent Contributor
  • **
  • Posts: 999
  • Country: gb
Re: Most stable VPG parts, HZ or VHP?
« Reply #3 on: June 10, 2018, 10:45:17 pm »
It's also interesting to note that the VHZ,VPG, VHP203 etc. specs state typical shelf life stability of 2ppm for at least 6 years, whereas the VH series specify maximum drifts of 5ppm for 1 year and 10ppm for 3 years.

So which is the better spec? Do they have similar drifts in practice? :-//


[EDIT: Changed 3ppm to 5ppm]
« Last Edit: June 11, 2018, 02:34:48 pm by splin »
 

Offline CalMachine

  • Frequent Contributor
  • **
  • Posts: 469
  • Country: us
  • Metrology Nut
Re: Most stable VPG parts, HZ or VHP?
« Reply #4 on: June 11, 2018, 02:51:17 am »
HZ series wins in the stability department for reference purposes.

VH series has shelf life of 5ppm after 1yr and 10ppm after 3yr, while the VHP and HZ series both have shelf life of 2ppm after 6 years.

Now, if your looking at stability at rated power this is where HZ partly shines over VHP.  HZ is rated at 20 ppm / 2000 hrs at rated power (0.3W+ at 25C) while the VHP is rated at 50 ppm / 2000 hrs at rated power (0.3W at 70C). 

I often wonder if they are the same resistors but catered to different applications, hence the different operating temperature specifications
All your volts are belong to me
 

Offline quarks

  • Frequent Contributor
  • **
  • Posts: 850
  • Country: de
Re: Most stable VPG parts, HZ or VHP?
« Reply #5 on: June 11, 2018, 02:53:43 am »
Before I bought my first VPG resistors, I had several conversations with a VPG representative, who gave me very good information and highly suggesteted to go for VHP 101 resistors if TC matters.
 
The following users thanked this post: kj7e

Offline TiN

  • Super Contributor
  • ***
  • Posts: 4370
  • Country: us
  • PPM Alert!
    • xDevs.com
Re: Most stable VPG parts, HZ or VHP?
« Reply #6 on: June 11, 2018, 04:18:01 am »
Comparing "20 ppm / 2000 hrs at rated power (0.3W+ at 25C)" vs "50 ppm / 2000 hrs at rated power (0.3W at 70C)"
That is not correct though, due to aging is not same at elevated temp.

VPG representative, who gave me very good information and highly suggesteted to go for VHP 101 resistors if TC matters.
Same info I got before as well.  :)
YouTube | Metrology IRC Chat room | Let's share T&M documentation? Upload! No upload limits for firmwares, photos, files.
 

Offline CalMachine

  • Frequent Contributor
  • **
  • Posts: 469
  • Country: us
  • Metrology Nut
Re: Most stable VPG parts, HZ or VHP?
« Reply #7 on: June 11, 2018, 12:16:40 pm »
Comparing "20 ppm / 2000 hrs at rated power (0.3W+ at 25C)" vs "50 ppm / 2000 hrs at rated power (0.3W at 70C)"
That is not correct though, due to aging is not same at elevated temp.
What is not correct?  The 70C spec?  It's right on their datasheet.
« Last Edit: June 11, 2018, 12:19:41 pm by CalMachine »
All your volts are belong to me
 

Offline TiN

  • Super Contributor
  • ***
  • Posts: 4370
  • Country: us
  • PPM Alert!
    • xDevs.com
Re: Most stable VPG parts, HZ or VHP?
« Reply #8 on: June 11, 2018, 12:33:59 pm »
It is not apples to apples comparison. One thing I learned about high stability parts - one cannot predict aging just by accelerated method via high temperature alone.
YouTube | Metrology IRC Chat room | Let's share T&M documentation? Upload! No upload limits for firmwares, photos, files.
 

Offline CalMachine

  • Frequent Contributor
  • **
  • Posts: 469
  • Country: us
  • Metrology Nut
Re: Most stable VPG parts, HZ or VHP?
« Reply #9 on: June 11, 2018, 01:55:21 pm »
It is not apples to apples comparison. One thing I learned about high stability parts - one cannot predict aging just by accelerated method via high temperature alone.

I realized it's not a direct apples to apples comparison...  hence the last sentence of my post.


I often wonder if they are the same resistors but catered to different applications, hence the different operating temperature specifications
« Last Edit: June 11, 2018, 01:57:01 pm by CalMachine »
All your volts are belong to me
 

Online splin

  • Frequent Contributor
  • **
  • Posts: 999
  • Country: gb
Re: Most stable VPG parts, HZ or VHP?
« Reply #10 on: June 11, 2018, 04:51:05 pm »
HZ series wins in the stability department for reference purposes.

How did you deduce that? VHP101 has a lower guaranteed TC from 15 to 45C than HZ and the same shelf stability specification. Or are you saying that in your experience that HZ outperform the VHP series drift wise?

Quote
VH series has shelf life of 5ppm after 1yr and 10ppm after 3yr, while the VHP and HZ series both have shelf life of 2ppm after 6 years.

I guess you didn't read my post immediately prior to yours? The VH 10ppm/3 years spec is a maximium whereas the 2ppm/6 years spec for the VHZ and VHP series are typical figures. The latter may be better/worse or identical to the VH series but there is no way to tell from the datasheet.
 

Offline martinr33

  • Frequent Contributor
  • **
  • Posts: 267
  • Country: us
Re: Most stable VPG parts, HZ or VHP?
« Reply #11 on: June 11, 2018, 05:16:37 pm »
I'd expect these parts to come from the same production run.

I doubt that they are sorting, other than for initial resistance and maybe thermal drift. Given the time needed to measure stability, I'd expect them to be doing some conditioning (as per the datasheet, time, temperature and controlled overload) and then testing after that. They also suggest that more conditioning can make the parts better.

 

Offline CalMachine

  • Frequent Contributor
  • **
  • Posts: 469
  • Country: us
  • Metrology Nut
Re: Most stable VPG parts, HZ or VHP?
« Reply #12 on: June 11, 2018, 09:45:42 pm »
HZ series wins in the stability department for reference purposes.

How did you deduce that? VHP101 has a lower guaranteed TC from 15 to 45C than HZ and the same shelf stability specification. Or are you saying that in your experience that HZ outperform the VHP series drift wise?

I didn't deduce it.  Vishay states it in their HZ datasheet. 

Quote
"When combined with the hermetic sealing and oil filling, the
HZ Series resistors become the most precise and stable
resistors available. They are used as the most precise
secondary standards for ultra precision metrology. "

Also, I was strictly referring to stability/load life of the resistor, in reference conditions, not TCR.  Since most reference resistors will most likely only be used ~25C, one has to look to those specs.

If you want to compare Vishay's voodoo specs, HZ still wins.  Look at the graph Figure 4 on each datasheet and across your 15C-45C zone.  HZ  Typical TCR curve is 0.05 ppm/C while VHP typical TCR curve is 0.3 ppm/C.   Sure, you might find differing specs elsewhere.. but that's one of the spots you can get an apples to apples comparison of specs.


Quote
VH series has shelf life of 5ppm after 1yr and 10ppm after 3yr, while the VHP and HZ series both have shelf life of 2ppm after 6 years.
I guess you didn't read my post immediately prior to yours? The VH 10ppm/3 years spec is a maximium whereas the 2ppm/6 years spec for the VHZ and VHP series are typical figures. The latter may be better/worse or identical to the VH series but there is no way to tell from the datasheet.

While it doesn't state 'maximum' in the VHP or HZ series datasheets, it also doesn't state that they are typical values either.  Normally to take something as a 'typical' value, it has to state that.  Has anyone confirmed that the 2ppm over 6 year shelf life is a typical spec?  Even so, I'd much rather have a typical 2ppm/6 years than a MAX of 5 ppm/1 year  All. Day. Long.
All your volts are belong to me
 
The following users thanked this post: kj7e

Offline kj7e

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: us
  • Damon Stewart
Re: Most stable VPG parts, HZ or VHP?
« Reply #13 on: June 11, 2018, 10:16:09 pm »
Zlymex cut open a VHA518-7, 100 Ohm part in this post; https://www.eevblog.com/forum/metrology/teardown-standard-resistors/msg891676/#msg891676

It does appear the -7 stands for the number of elements.  At least in this case they are all in parallel, so I'm still thinking the multiple parallel elements could be responsible for a better long term shelf life.  Also, since these parts have a much higher power rating that will likely never used in a reference application, there will be less load life effect on the parts.  I'm just speculating on why the HZ parts may be used by those who make and sell resistance standards.  I can easily see for a lab reference even if the TC is not quite as good as the VHP101 long term drift is more important.  Found some prices for some 4 wire 10K VHA518 -7 and -11 with 0.001% tolerance, not exactly cheap... but doable.  I sent an email with some questions to a Vishay App Engineer, my email was forwarded App Engineering Manager in Israel to answer.
 

Offline plesa

  • Frequent Contributor
  • **
  • Posts: 965
  • Country: se
Re: Most stable VPG parts, HZ or VHP?
« Reply #14 on: June 11, 2018, 10:39:45 pm »
Zlymex cut open a VHA518-7, 100 Ohm part in this post; https://www.eevblog.com/forum/metrology/teardown-standard-resistors/msg891676/#msg891676

It does appear the -7 stands for the number of elements.  At least in this case they are all in parallel, so I'm still thinking the multiple parallel elements could be responsible for a better long term shelf life.  Also, since these parts have a much higher power rating that will likely never used in a reference application, there will be less load life effect on the parts.  I'm just speculating on why the HZ parts may be used by those who make and sell resistance standards.  I can easily see for a lab reference even if the TC is not quite as good as the VHP101 long term drift is more important.  Found some prices for some 4 wire 10K VHA518 -7 and -11 with 0.001% tolerance, not exactly cheap... but doable.  I sent an email with some questions to a Vishay App Engineer, my email was forwarded App Engineering Manager in Israel to answer.

Yes -7 or -11 stand for amount of elements. What is rationale behind 0.001% tolerance? It will make it little bit expensive. Price tag of VHA518-11 4wire was 200-400 EUR. 
 

Offline kj7e

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: us
  • Damon Stewart
Re: Most stable VPG parts, HZ or VHP?
« Reply #15 on: June 11, 2018, 10:51:16 pm »
Plesa,

Because it's there - GM

No particular reason or need, If I'm going to order one and wait 15 weeks to get it I'd like it as close to exact as possible.
« Last Edit: June 11, 2018, 11:33:35 pm by kj7e »
 

Offline plesa

  • Frequent Contributor
  • **
  • Posts: 965
  • Country: se
Re: Most stable VPG parts, HZ or VHP?
« Reply #16 on: June 12, 2018, 08:58:50 pm »
No particular reason or need, If I'm going to order one and wait 15 weeks to get it I'd like it as close to exact as possible.

Mine units has much longer lead time, even with much tighter spec. If there will be interest I can sacrifice one VHA518-11Z 10k 4W unit as travelling standard.
 
The following users thanked this post: kj7e

Offline e61_phil

  • Frequent Contributor
  • **
  • Posts: 925
  • Country: de
Re: Most stable VPG parts, HZ or VHP?
« Reply #17 on: June 12, 2018, 09:03:29 pm »
No particular reason or need, If I'm going to order one and wait 15 weeks to get it I'd like it as close to exact as possible.

Mine units has much longer lead time, even with much tighter spec. If there will be interest I can sacrifice one VHA518-11Z 10k 4W unit as travelling standard.

Tighter than 10ppm at Vishay?
 

Offline plesa

  • Frequent Contributor
  • **
  • Posts: 965
  • Country: se
Re: Most stable VPG parts, HZ or VHP?
« Reply #18 on: June 12, 2018, 09:29:19 pm »
No particular reason or need, If I'm going to order one and wait 15 weeks to get it I'd like it as close to exact as possible.

Mine units has much longer lead time, even with much tighter spec. If there will be interest I can sacrifice one VHA518-11Z 10k 4W unit as travelling standard.

Tighter than 10ppm at Vishay?
No, I mean that I will expect much longer lead time for 10 ppm resistor compare to 50 ppm.
 

Offline TiN

  • Super Contributor
  • ***
  • Posts: 4370
  • Country: us
  • PPM Alert!
    • xDevs.com
Re: Most stable VPG parts, HZ or VHP?
« Reply #19 on: June 13, 2018, 04:24:57 am »
I'm getting close to 20 weeks for my standard VHP20x parts with 0.1% tolerance already.
YouTube | Metrology IRC Chat room | Let's share T&M documentation? Upload! No upload limits for firmwares, photos, files.
 

Offline kj7e

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: us
  • Damon Stewart
Re: Most stable VPG parts, HZ or VHP?
« Reply #20 on: June 15, 2018, 03:45:57 pm »
Just got off the phone with one of the Vishay App Engineers, learned a few things.  The VHP100/101's use positive and negative TC compounds to achieve very low TC, the VHA's do not, so the VHA's will often times have more TC drift.  The advantage to the VHA's is load life stability.
 
The following users thanked this post: TiN, hwj-d, CalMachine

Offline plesa

  • Frequent Contributor
  • **
  • Posts: 965
  • Country: se
Re: Most stable VPG parts, HZ or VHP?
« Reply #21 on: June 17, 2018, 11:33:35 am »
Just got off the phone with one of the Vishay App Engineers, learned a few things.  The VHP100/101's use positive and negative TC compounds to achieve very low TC, the VHA's do not, so the VHA's will often times have more TC drift.  The advantage to the VHA's is load life stability.

Did he confirmed leadtime? I'm little bit curious what it will be for 10ppm tolerance.
I assume they will needs to manufacture larger quantity of chips and laser trim them more carefully.
I just printed small box for 10k VHA518-11Z with PMO as travelling standard.
 
The following users thanked this post: kj7e, hwj-d

Offline quarks

  • Frequent Contributor
  • **
  • Posts: 850
  • Country: de
Re: Most stable VPG parts, HZ or VHP?
« Reply #22 on: June 17, 2018, 12:33:59 pm »
if I remember correctly VPG has 3 alloy foils (C, K and Z) and the Z-foil is the one to go for.
 

Offline kj7e

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: us
  • Damon Stewart
Re: Most stable VPG parts, HZ or VHP?
« Reply #23 on: June 17, 2018, 01:06:59 pm »
Plesa,  I was told about 20 weeks lead time.

Flinstone,  Its always possible the I was given incomplete or bad info, but what I wrote was what I was told.  It was also mentioned shelf life between the VHP100/101 and the VHAxZ's would be nearly the same, it was the load life that separated them.  They where pretty clear the VHP100/101's (and those two where specifically mentioned) would generally yield better TC than the VHAxZ's due to the opposing TC compound constriction and this was not the case with the latter.
 
The following users thanked this post: chris_11

Offline kj7e

  • Frequent Contributor
  • **
  • Posts: 864
  • Country: us
  • Damon Stewart
Re: Most stable VPG parts, HZ or VHP?
« Reply #24 on: June 17, 2018, 01:23:14 pm »
Had a call with both;

Kip Reiner
Sr. Field Design Engineer
VPG Foil Resistors
Western Americas Region

And

Steve Phillips
Sr. Application Engineer /
Quality Assurance
VPG Foil Resistors
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf