Most stable VPG parts, HZ or VHP?

[kj7e]

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?

[TiN]

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.

[kj7e]

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.

[splin]

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]

[CalMachine]

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

[quarks]

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.

[TiN]

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. 

[CalMachine]

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.

[TiN]

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.

[CalMachine]

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

[splin]

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?

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.

[martinr33]

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.

[CalMachine]

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. 

"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.

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.

[kj7e]

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.

[plesa]

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. 

[kj7e]

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.

[plesa]

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.

[e61_phil]

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?

[plesa]

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.

[TiN]

I'm getting close to 20 weeks for my standard VHP20x parts with 0.1% tolerance already.

[kj7e]

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.

[plesa]

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.

[quarks]

if I remember correctly VPG has 3 alloy foils (C, K and Z) and the Z-foil is the one to go for.

[kj7e]

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.

[kj7e]

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

[quarks]

Dear Quarks - I have following extra info (from John):

These are two chip devices.....an S foil, they use in S102 resistors, and a K foil which they use in S102K. These have opposite polarity second order terms, ie the parabolas are inverted. I think that is standard for the VHP101 and VHP102. However,  Vishay can also apply a 48 hour 125C unpowered burn-in process - called PMO

Z foil can be very good and is probably better if power is dissipated (which is the case for the 10R) because, to balance the parabolas, different values need to be used in a ratio of about 3:1 (the ratio of of second order term magnitude) and therefore the two chips will dissipate power differently and run at slightly different temperatures under power.

Best regards
Flinstone

ps.: It is correct that VPG also used C foil (K & S) as terminology ...

Hello Flinstone,

I am not sure if we have a simple misunderstanding, because I am with you.

In my reply about the 3 alloy foils (C, K and Z) I think/hope this is still correct (but it is only from memory several years back).
Therefore my suggestion was/is to go for option with Z-Foil (e.g. VHA51x-xZ) if it is available.

About "S-Foil" my understanding was/is, S-Foil is not an alloy foil, but a combination of C-Foil alloy resistors and K-Foil alloy resistors.
If that is wrong it would be great if you can share some more details.

bye
quarks

[plesa]

Box finished. I will measure tempco in +/-10°C if measurable with my test gear.
Anyone interested as travelling standard?

[quarks]

looks good to me, thanks for sharing
If you are willing to send it to Germany I am interested.

Out of curiosity, are you planning to add a temp sensor?
Did you get a calibration certificate from VPG?

[Magnificent Bastard]

Box finished. I will measure tempco in +/-10°C if measurable with my test gear.
Anyone interested as travelling standard?

I LIKE this!

[Gyro]

You'll be lucky in Antarctica! 

[borghese]

I'm interested if you send to Slovenia
Thank you

[cellularmitosis]

A little ways down the road (when I am set up for ohm-nutting), I'd be happy to pay to have it shipped to the US!

[plesa]

looks good to me, thanks for sharing
If you are willing to send it to Germany I am interested.

Out of curiosity, are you planning to add a temp sensor?
Did you get a calibration certificate from VPG?

No, I did not asked for it.
Yes, adding Pt100 will be piece of cake Is there any connector to outside world preferred?

[quarks]

to bad, you did not ask as I think they should have the data anyway
about Pt100, I would go for a 4wire connection with normal binding posts
That should be the easiest way to connect a DMM

[plesa]

to bad, you did not ask as I think they should have the data anyway
about Pt100, I would go for a 4wire connection with normal binding posts
That should be the easiest way to connect a DMM

My idea was to use some mini DIN or some screw socket. I needs to search little bit.
Also found few 10k PWW from Edwin (708 type).
Another box with Edwin PWW  is made and can be shipped with VHA518 box.

[Pipelie]

if I remember correctly VPG has 3 alloy foils (C, K and Z) and the Z-foil is the one to go for.

[quarks]

My idea was to use some mini DIN or some screw socket. I needs to search little bit.
Also found few 10k PWW from Edwin (708 type).
Another box with Edwin PWW  is made and can be shipped with VHA518 box.

You can choose any connector you prefer, but then you have to have a mating connecting cable for your DMM.
That is why I would use easy to connect binding posts in my own design.

About WW resistors, if you use a single resistor I do not think you can get as good as your VHA.
Most likely you would need to match two with opposite canceling TCR.

[Pipelie]

the chart I posted yesterday is from this book. Mechatronics: Ideas for Industrial Applications. page 289.
I don't have it, you guys can buy it or read it on google books if you want.

and attached two documents which also have the similar chart.

http://www.vishaypg.com/docs/49788/10reasns.pdf
http://www.uhpresistors.com/doc/10reasons.pdf

[meandeev]

Hello,

I´m also interested in germany (like the user quarks, maybe after him), if you are willing to send to our country.

Box finished. I will measure tempco in +/-10°C if measurable with my test gear.
Anyone interested as travelling standard?

[Echo88]

Virtually no TCR at all in all virtually bought resistors.

[leighcorrigall]

Box finished. I will measure tempco in +/-10°C if measurable with my test gear.
Anyone interested as travelling standard?

Am I a bit late for shipping to Canada? I would like to try measuring it with my Advantest R6581T. 

[leighcorrigall]

 

...
Did you get a calibration certificate from VPG?

I have decided to purchase a 4-wire lead 10 kΩ resistor Y473310K0000S0L (VHA518-11Z) with post-manufacturing operations (PMO) from Vishay Precision Group to act as a transfer standard for my Advantest R6581T 8.5-digit multimeter. My plan is to mount the resistor in a shielded box and crimp LowThermal ring terminals onto the leads so that I can fasten them to 2758 Series LowThermal binding posts. This should avoid any potential soldering damage and allow simple disassembly if required in the future. If anyone is interested, I have attached Technical Note 103 on soldering foil resistors. The applications engineer provided me with some additional options (there are likely more, but some might be exclusive to manufacturers and other more valuable customers):

- perform a resistance check and record with each resistor and send the data to me OR Vishay can supply a NIST certification 
- Vishay can also supply a non-standard lead at 80 mm [3.15 in] length instead of 25.4 mm with optional sheathing (I am merely informing members and do not intend to go with these options)

My assumption is that the VHA518 resistor will experience the most amount of change during the first year. This is why PMO is desirable for my resistance standard application. According to the Field Design Engineer, the procedure for PMO is custom and based on the clients' design intention. They did not elaborate on their techniques, but they said that they would focus on stability in order to ensure performance via a minor PMO for this single resistor purchase. Would it be practical to choose the NIST certificate option that likely costs significantly more, or should I go with the simple 'resistance check with record' option and have the resistor checked again in a year's time by a calibration lab? In practice, the minor PMO should remove much of the initial drifting, but I do not have enough information to quantify the effectiveness of this optional step. My guess is that I am overthinking things and I should simply be grateful for their 'check with record' offer. What do you think?

Regards.

[ramon]

Do they allow anyone to order 1 single piece, or it's just you? Did they told you how much would cost PMO, and measurement? It seems an easy way to get your own standard.

[leighcorrigall]

Do they allow anyone to order 1 single piece, or it's just you? Did they told you how much would cost PMO, and measurement? It seems an easy way to get your own standard.

They seem to be prepared to quote single-unit orders. I am still in the process of the request, but they should email me soon about the price. The HZ Series is intended for metrology, so yes.

I will be ordering a resistor from AVNET.com with a custom part number provided by Vishay. The base cost is 315.33 USD and there is a 16 week factory lead time. I assume it will be more expensive with the PMO option and take longer to prepare as a result. If you aren't in an immediate hurry for a secondary standard, this is a good option.

[leighcorrigall]

...

The applications engineer provided me with some additional options (there are likely more, but some might be exclusive to manufacturers and other more valuable customers):

- perform a resistance check and record with each resistor and send the data to me OR Vishay can supply a NIST certification 
- Vishay can also supply a non-standard lead at 80 mm [3.15 in] length instead of 25.4 mm with optional sheathing (I am merely informing members and do not intend to go with these options)
...

"The RC check would add about a 1 USD per unit and the NIST would be a 40 USD minimum and would increase after 15 units" -- Vishay Applications Engineer

For 40 USD per unit, a NIST calibration is an absolute deal! 

My local calibration laboratory would charge considerably higher to perform the same service. 

It's kind of a joke to me that it is cheaper just to buy a calibrated secondary transfer standard set (10 DCV Zener buffer reference and 10 kΩ).

[leighcorrigall]

Do they allow anyone to order 1 single piece, or it's just you?

The minimum order quantity (MOQ) is 1. I do not think I am in any way being given special preference. 

[leighcorrigall]

...

The base cost is 315.33 USD and there is a 16 week factory lead time. I assume it will be more expensive with the PMO option and take longer to prepare as a result. If you aren't in an immediate hurry for a secondary standard, this is a good option.

With the stability/resistivity PMO option and a NIST calibration (40 USD), the resistor was quoted at 503.62 USD to date. The shipping estimate is given as November 19th, 2021 (23 week factory lead time). Luckily, I have a few other Vishay VHP100 Series resistors which will keep me occupied for the time being. I am going to go ahead with the purchase. The distributor I was assigned by Vishay was ELcoPC who is situated in Pennsylvania state.

Now there is plenty of time to design the enclosure! 

[RandallMcRee]

Leigh,
Just curious do you know that Texas Components sells metrologycalibration standard resistors? Seems like a good deal given what you are going through? Or not.

http://webdirect.texascomponents.com/SearchResults.asp?Cat=1839

[leighcorrigall]

Leigh,
Just curious do you know that Texas Components sells metrologycalibration standard resistors? Seems like a good deal given what you are going through? Or not.

http://webdirect.texascomponents.com/SearchResults.asp?Cat=1839

I am new to this realm of engineering and am not aware of this company. Thank you for bringing this company to my attention. The specifications are certainly tempting. Are banana plugs an option for 8.5-digit DMM calibrations?

[RandallMcRee]

Leigh,
Just curious do you know that Texas Components sells metrologycalibration standard resistors? Seems like a good deal given what you are going through? Or not.

http://webdirect.texascomponents.com/SearchResults.asp?Cat=1839

I am new to this realm of engineering and am not aware of this company. Thank you for bringing this company to my attention. The specifications are certainly tempting. Are banana plugs an option for 8.5-digit DMM calibrations?

I have not used that TXSFR standard myself, but it looks like it directly plugs into your (and my!) 6581T for cal purposes. I believe the same spacing is also useful for a 3458a. It is a nice feature of the 6581 and 3458a that they allow this type of calibration.

If the meter calibration requires leads I guess the company sells an adapter of some sort (or you can make one).

[leighcorrigall]

...

I have not used that TXSFR standard myself, but it looks like it directly plugs into your (and my!) 6581T for cal purposes. I believe the same spacing is also useful for a 3458a. It is a nice feature of the 6581 and 3458a that they allow this type of calibration.

If the meter calibration requires leads I guess the company sells an adapter of some sort (or you can make one).

Although this is completely off-topic, I think a better solution would be:
https://www.ab-precision.de/products/electrical-standards/

The product is from a forum member named Adrian Bernhard. He also makes shielded cables. 

[leighcorrigall]

Leigh,
Just curious do you know that Texas Components sells metrologycalibration standard resistors? Seems like a good deal given what you are going through? Or not.

http://webdirect.texascomponents.com/SearchResults.asp?Cat=1839

In retrospect, I believe this turnkey product is just a Vishay resistor inside a pre-assembled box, judging by the language and diagrams from the datasheet. If this is true, then it's likely cheaper just to buy the top-quality VHP100 and an enclosure.

PS, I replaced the Advantest R6581T front banana jack sockets with LowThermal 2758 Series binding posts so that I could avoid calibrating the system with banana plug connections. I might be overthinking things...

[kj7e]

Leigh,
Just curious do you know that Texas Components sells metrologycalibration standard resistors? Seems like a good deal given what you are going through? Or not.

http://webdirect.texascomponents.com/SearchResults.asp?Cat=1839

In retrospect, I believe this turnkey product is just a Vishay resistor inside a pre-assembled box, judging by the language and diagrams from the datasheet. If this is true, then it's likely cheaper just to buy the top-quality VHP100 and an enclosure.

Sometimes that is exactly the case,  see this post for an example;
https://www.eevblog.com/forum/metrology/teardown-standard-resistors/msg891676/#msg891676

[leighcorrigall]

I have decided to purchase a 4-wire lead 10 kΩ resistor Y473310K0000S0L (VHA518-11Z) with post-manufacturing operations (PMO) from Vishay Precision Group to act as a transfer standard for my Advantest R6581T 8.5-digit multimeter.

...

This may seem trivial, but I noticed last week that on the bottom of page 4 of the HZ Series (Z-Foil) resistor datasheet the actual part number for a 4-terminal resistor is 302075-11Z (Y4733). Vishay should really standardize their part numbers. I really don't understand why there are multiple order numbers for the same part.