Resistors With Steel Leads

[Nigel Goodwin]

We throw stacks of CRT TV's away because of water damage....pot plants on top of them...all caused by the customer watering the pot plant with too much water and that runs into the tv etc,etc.

Doesn't happen any more, because you can't put plants on top of LCD sets

 

[atferrari]

When starting in this hobby, 40++ years ago, I got free components for my first AM xmtr (a modified CW in the 40 & 80 m band) by disassembling old RF gear. I can presume that some had been built not less than 60 years ago (GE, Ericson and maybe Siemens, but not sure about this last).

Resistors (some 100s of them) besides of big size, had leads which I believe were pure copper with no visible magnetic behavior. Yesterday, digging deep in my resistor box (10K) I run across one (the very last?) and snipped the terminals. They look as pure copper.

When I finally started buying components for smaller circuits I soon realized they were different, being weakly attracted by a magnetized tweezer. The same with caps, xtals and, IIRC, electret microphones.

By passing a magnet close to the tray where I collect all the snipped terminals I can lift the whole bunch somehow.

 

[tvtech]

Doesn't happen any more, because you can't put plants on top of LCD sets

Yeah...it's true. Things change though....you will be amazed at the amount of inquiries we get now from locals who have started using/buying small flat screen TV's....all have cracked/destroyed screens....I ask why and how did it happen?.......always the same answer.....fell off the wall.

Go figure.

Crazy stuff

 

[tvtech]

Talking about Copper and stuff...we had sets manufactured under License locally by "Panasonic" in Parow South Africa.

Came with proper Copper heat sinks for the 5V rail and some other cooling too. Early sets. FX51 and FX54 come to mind. Later in production...they went to Aluminum..and then just any kind of metal will do. Like anything.

Looking back now I realize how brands stuff up. All about profit...

Anyway, I already took this thread way off Topic.

Nice for me to share though

tv

 

[MrAl]

But the result of that is you will NEVER get anything done, steel wires in components have been commonplace for decades, and it's crazy imagining magnetic and skin effects etc. As for your 1.01A suggestion, that's just as crazy - it's within 1%, which is likely to be considerably better than the tolerances of any components involved.

Look at an old CRT TV PCB that's been out in the rain or water damaged in some way, it's VERY common for the component leads to be rusted, because they are steel and not copper - it makes no difference.

Hi there Nigel,

I am not sure what you mean, "get anything done". What is it that should get done here? I dont really have to rush on this either so we can take our time and hear all the inputs.

Your input is that it doesnt matter, and that's fine and that's appreciated, and i wont try to judge your reasoning. However, when you say that 1 percent is good enough for the current measurement, you must realize that sometimes we shoot for better than 1 percent, like 1/2 percent or even 0.1 percent. I still use 5 percent resistors (mostly because i already had them) and i also use 1 percent resistors, but i also have some 0.1 percent resistors. If we have 0.1 percent resistors and 1 percent is always good enough, then we have to question why anyone would bother making these guys. Dont get me wrong here though, most of the time i use 1 percent resistors unless i want to use one of my slightly older ones that are 5 percent but they are smaller so they fit in smaller places. Most of the time it doesnt matter, as you noted, but sometimes it is important. So the key word here i think is "always". Is 1 percent really *always* good enough, or do we sometimes need better?

To help answer that question i look to the web and at home. What i find is the following.
I find 0.1 percent resistors.
I find one of my meters is around 0.05 percent.
I find my voltage calibration reference is, ready for this, 0.02 percent!

Should i throw out the 0.02 percent voltage reference? (Just kidding of course)

I value your opinion highly but sometimes i get the feeling you dont value mine. I could easily see it if i was a new member, but i think i've been here for a good enough while now to establish that most of the time i know what i am talking about
Maybe you read mostly my worst posts

 

[MrAl]

MrAl, you raise some interesting points.

I have previously noticed magnetic connecting leads, usually on semiconductor devices such as transistors and three terminal regulators.

I had a look at a random sample of my stock of resistors and I did not find any magnetic leads.
However all the resistors which I tested had something magnetic within the body of the resistor. I assume that this is the end caps which connect onto the ceramic former of the resistor where the carbon or ceramic film is deposited.

I have no idea of the effect of the magnetic leads in the impedance of the resistor, if this is something you wish to study further, don't forget that the resistor is "adjusted" during manufacture by laser etching a spiral in the carbon/copper film. This in itself will have a small amount of inductance.

A quick examination of other components showed that some electrolytic capacitors had magnetic leads, as had some quartz crystals.

JimB

Hi there Jim,


Nigel is pretty sure that there is no problem, and i agree for the most part. It's just that it would be nice to have some technical data. There might be some somewhere, that is part of the reason i started this thread.

John mentioned that the resistor body itself could be semi inductive, and because of that it might swamp any lead reactance. Makes a lot of sense.

I think i remember some of my crystals having steel leads too, the 2MHz ones. Maybe they found that the plating conducts most of the current anyway, but again, some data would be nice

 

[Nigel Goodwin]

John mentioned that the resistor body itself could be semi inductive, and because of that it might swamp any lead reactance. Makes a lot of sense.

Why would a steel wire have any different reactance to a copper one?, and no disrespect, but I'm even more baffled by your concern over steel vs copper when you apparently didn't know about the often inductive nature of resistors? - presumably you're not a radio ham?.

Any conductor has inductance, that's what a 'lecher line' is - simply a straight conductor, used as an inductor - they make them out of any kind of conductor, including copper PCB traces.

My 'concern' over this issue is you're decades too late to be discussing it - it's nothing 'new' it happened well before the end of the last century

 

[dr pepper]

Not heard from you in a while tellytech.

 

[tvtech]

tellytech new one

Till later dr pepper

tv

 

[Tony Stewart]

• Standard lead wire for CF/CFM is copper plated steel, with 100% tin over plate
• type CFQ/CFQM as 100% tin plate on copper wire is available ( extra cost)
ref Stackpole

Plated steel resistors have been the norm. in my experience.

I could tell the quality of the steel by the distance traveled by the snipped lead using sharp side cutters. (Japan Steel was the best)
Being very strong, very plastic ( not elastic) easily re-shaped, not brittle, low risk of rusting, yet with sharp breaking point with edge cutters the end-piece could easily fly across the lab with great velocity.

Copper is more plastic when cut and doesn't fly as far with precise side cutters. ( not the shear type )

- not very scientific but resistors have very stringent quality controls and test criteria.

They don't all* specify the iron content in the leads for a reason, low cost. If you need copper, you have to ask for it.

Erata...
- plated screws on the other hand, are poor for resisting rust.
-< 10u" gold wire bonds have been standard for over 6 decades for reliability on metallurgic reactions,
- Recently many LEDs now have gone towards Aluminum wirebonds. Not sure about SMT IC's possibly.

 

[schmitt trigger]

With the advent of high speed automatic insertion equipment, component leads were slowly upgraded to steel alloys. The keyword is ALLOYS. Steel properties change dramatically with alloying materials.
For instance, stainless steel is non magnetic.

Steel does not adhere to solder, therefore they are are plated with a barrier metal (typically nickel) to which 100% matte tin is applied.

This improves many aspects of automatic insertion, while also lowering costs.

Copper is still used whenever the lowest resistivity or highest heat conduction is required.

 

[MrAl]

Why would a steel wire have any different reactance to a copper one?, and no disrespect, but I'm even more baffled by your concern over steel vs copper when you apparently didn't know about the often inductive nature of resistors? - presumably you're not a radio ham?.

Any conductor has inductance, that's what a 'lecher line' is - simply a straight conductor, used as an inductor - they make them out of any kind of conductor, including copper PCB traces.

My 'concern' over this issue is you're decades too late to be discussing it - it's nothing 'new' it happened well before the end of the last century

Hi again Nigel,

Thanks for discussing this intelligently, i greatly appreciate that.

Steel has a higher relative permeability than copper, much higher, although i have found that most of the time it is not nearly as high as a good inductor core might be such as 1000. It comes out closer to about 100, but that's still 100 times what copper is. So it seems to make sense that the skin effect would be different for steel than copper, and this also seems to be proved by any of the approximate formulas for calculating the skin effect, where the permeability enters into the formula. With the permeability in the formula, that means the skin effect changes for every metal, not just iron. How much it changes is based on the permeability of that metal, although it may not be strictly proportional it may be proportional to the square root, which would make it less sensitive to a change in metal. However, since steel can be 100 that could still mean a 10 to 1 change over either air or copper or other mostly non magnetically active materials.
This difference in permeability is probably the most important factor for why i was looking into this in the first place.

Also i might add that not all resistors are made the same way whether they have steel leads or not.

From the other replies it is starting to sound like the difference might only be noticeable for low value resistors where we want the resistance to be very low, but i still dont have any hard data on any of this.

You are right that i have not worked in radio very much. I do wonder if anyone seriously involved in ham radio has ever looked into this.

In the past i have looked into things and found problems that many others have overlooked, and that was simply because i took the time to look. In grammar school i found errors in a math textbook that were taken as true and correct for several years before that, and i only found this because i took the time to look.
Since then i have found errors in many types of technical literature.

 

[MrAl]

With the advent of high speed automatic insertion equipment, component leads were slowly upgraded to steel alloys. The keyword is ALLOYS. Steel properties change dramatically with alloying materials.
For instance, stainless steel is non magnetic.

Steel does not adhere to solder, therefore they are are plated with a barrier metal (typically nickel) to which 100% matte tin is applied.

This improves many aspects of automatic insertion, while also lowering costs.

Copper is still used whenever the lowest resistivity or highest heat conduction is required.

Hi there,

That's a good point. I had forgotten about the heat conduction aspect. Even brass is about 4 times less conductive than copper, and cooling through the leads is an important aspect of some package designs. Most simply and notable is some higher power diodes, like the 3 watt types. They rely on heat conduction through the leads for cooling. If they had brass leads they could burn up where with copper leads they would survive as normal. I suppose steel is bad for conducting heat too much like brass. We could look it up i guess.

As others have mentioned, the upside is the strength of the lead, where it can survive much more physical abuse.

I really appreciate these replies as we can start to build up a profile of the comparisons and i see we did find some differences already even if not associated that much with the inductance or AC conductance.

 

[KeepItSimpleStupid]

For instance, stainless steel is non magnetic.

That's not always true. See the 400 Stainless series. https://www.pennstainless.com/stainless-grades/400-series-stainless/

 

[MrAl]

That's not always true. See the 400 Stainless series. https://www.pennstainless.com/stainless-grades/400-series-stainless/

Hi,

Yes that's a good point too. The so called non magnetic grades have relative permeability up to maybe 1.010 at most (barely above air) while the so called magnetic grades go up to maybe 10 at most. 10 is a lot higher than 1 though, but from a functional stand point it is probably not 10 times worse just about 3 times worse. Regular steel would be worse i think, as high as 100 which would mean about 10 times as worse i think.
Would be interesting to find out what kind of SS they use for component leads when they do use that.

 

[jpanhalt]

Has anyone in this thread established that SS is actually used in leads?

1) I can't see any reason for doing that.
2) It work hardens quite easily and some grades can become so hard that HSS and even carbide tools don't cut it.

John

 

[MrAl]

Has anyone in this thread established that SS is actually used in leads?

1) I can't see any reason for doing that.
2) It work hardens quite easily and some grades can become so hard that HSS and even carbide tools don't cut it.

John

Hi there John,

Well here's one reason...durability in harsh environments...not just the leads though, but the whole resistor
For one example, Vishay sells a "Metal Strip" resistor made of a proprietary mix that includes at least iron and chromium which i think qualifies it as a stainless steel, but they dont seem to want to release the entire list of metals included.
The resistance can be very very low, down to 200 micro ohms. I've never needed one that low myself though.

There are so many types and shapes of resistors out there it is almost mind boggling. No wait i take that back, it is mind boggling

 

[jpanhalt]

... Vishay sells a "Metal Strip" resistor made of a proprietary mix that includes at least iron and chromium which i think qualifies it as a stainless steel, but they dont seem to want to release the entire list of metals included.

This thread was about ordinary resistors, not some special purpose device for which you don't have any details.

Before we go further down the new tangent, please define what you mean by "qualifies as a stainless steel." That is, is any alloy that contains chromium and iron a "stainless steel" regardless of the relative proportions each metal or the inclusion of other metals and non-metals in the alloy?

John

 

[schmitt trigger]

That's not always true. See the 400 Stainless series. https://www.pennstainless.com/stainless-grades/400-series-stainless/

That is the reason I mentioned that steel properties do change significantly with alloying materials.
You are correct that certain SS varieties are mildly magnetic.

 

[schmitt trigger]

Has anyone in this thread established that SS is actually used in leads?

John

I only mentioned the SS as an example of how common steel properties change significantly with alloying. I didn't mean that it would be used as a resistor lead material.

Sorry for the confusion and throwing the thread into a tangent.