How long do components last? - Page 1
Forum section: electronics / general

author: MarkS
author_rank: Unknown
timestamp: February 14, 2012, 05:00:08 pm
content: I have a small collection of junk PCBs. There are tons of non-user serviceable parts that I want to take off. Of course I'll test the passives, but I am curious if there is an expected life span of passives, ICs and the like?

author: olsenn
author_rank: Frequent Contributor
timestamp: February 14, 2012, 05:18:04 pm
content: This is a good question. I know it will depend on the component (type, manufacturer, batch...) how long it will last, and it probably won't just die all of a sudden but rather will slowly slip out of spec and get worse exponentially over time. Electrolytic capacitors are particularly bad for crapping out over time, but generally, if you take care of the devices and don't oush them to the limits (or beyond) they will probably give you a reasonable lifespan. Typically IC's will become obsolete and undesireably long before they become non-operational.

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 14, 2012, 05:23:14 pm
content: Certain components are worked hard and therefore if the product was in service for a long time, I wouldn't bother. The biggest here is electrolytic capacitors. Even just sitting on the shelf, they can age to the point that you need to reform them.I have build circuits from TTL logic chips I pulled from an old Apple II (1977 or so date codes) and they work fine. Fine here describes as working with tolerance of parts back then. They consume orders of magnitude more than current chips with similar functions. From my experience, ICs will work.LEDs will still work. However, you may have to put 2 to 100 times more current for the same brightness of modern LEDs. I recently pulled out a 20 year old red LED and was pushing 50 mA to get it to full brightness. A new plain jane LED beat the light output in under 10 mA.Resistors if never over powered should be fine. Although the cost of these vs. just buying your own doesn't make sense unless you are getting some high power ceramics or something.

author: siliconmix
author_rank: Frequent Contributor
timestamp: February 14, 2012, 05:43:05 pm
content: Quote from: MarkS on February 14, 2012, 05:00:08 pmhave you tried getting a hot air gun and heating up the solder side and giving it a good slam on the bench works a treat.

author: timorousme
author_rank: Contributor
timestamp: February 14, 2012, 06:03:06 pm
content: The only thing you should really worry about would be electrolytic caps. Those usually have a lifespan of about 15 years, give or take.Even though I have had some in gear that's older than me and work OK, but I usually like to change them out.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 14, 2012, 06:03:39 pm
content: Quote from: sacherjj on February 14, 2012, 05:23:14 pmNot necessarily. For example, carbon composition resistors (e.g.Ohmite Little Demons) are highly susceptible to drifting out of spec over time if stored in an environment prone to humidity.

author: FenderBender
author_rank: Super Contributor
timestamp: February 14, 2012, 10:11:11 pm
content: Yeah but you rarely will find carbon composition in new equipment or in about anything within the last 25-30 years, from my experience. Some audio people like them because they are inherently noisy....not sure why you'd want that really but I don't do too much audio.Carbon comp is really old tech at this point. Carbon films are a little bit more reliable, though not perfect. Metal films I think are fine. Wirewounds should be fine also.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 15, 2012, 01:57:51 am
content: Oldfilm resistors of any type are probably OK,if you don't mind a bit of inductance.They were adjusted for resistance by making a spiral cut along the body to trim the value.I don't think they do that now,although that is the description on some websites.I remember many years ago doing a test at Tech College,where,we used a Q meter to calculate the inductance of various resistors.The old Philips carbon film was very much worse than carbon composition resistors.

author: timorousme
author_rank: Contributor
timestamp: February 15, 2012, 05:53:24 am
content: Quote from: FenderBender on February 14, 2012, 10:11:11 pmHere's a good article about the pleasing distortion in carbon comp resistors.http://www.geofex.com/article_folders/carbon_comp/carboncomp.htm

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 15, 2012, 07:24:47 am
content: Quote from: timorousme on February 15, 2012, 05:53:24 amI quit after "It's reputed to be imbued with almost mystical powers..."

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 15, 2012, 07:40:21 am
content: Quote from: vk6zgo on February 15, 2012, 01:57:51 amHave you been able to confirm this empirically or via datasheet reference?

author: wkb
author_rank: Super Contributor
timestamp: February 15, 2012, 07:47:42 am
content: Quote from: timorousme on February 14, 2012, 06:03:06 pmIt is not a given that elcos die after say 15 years. Good quality components, used within their design specs, last for decades. Silly designs with elcos next to overly-hot heatsinks cooking them are bad news of course. As are the infamous leaky tantalum caps.

author: timorousme
author_rank: Contributor
timestamp: February 15, 2012, 03:08:40 pm
content: Quote from: slateraptor on February 15, 2012, 07:24:47 amIf you know any amp builders/gearheads, you will see how true that statement is. It's crazy how much people are obsessed with the absurdly subtle "carbon comp tone."

author: tekfan
author_rank: Frequent Contributor
timestamp: February 15, 2012, 03:55:33 pm
content: Well here's a good RF site (none of that audiophool garbage) that talks about carbon comp resistors:http://www.w8ji.com/vhf_stability.htmLook closely at the cutaway of various resistors.

author: saturation
author_rank: Super Contributor
timestamp: February 15, 2012, 03:56:02 pm
content: Quite a long time, but it depends on how its used. Generally, derating parts, that is using it far below its maximum capacity, will make it last longer.The field of study is reliability, and the standard is a military handbook that estimates the lifespan of various components under operating conditions.You can find calculators online that use that handbook to calculate how long your parts will last.http://www.aldservice.com/en/reliability-software/free-mtbf-calculator.htmlI may have archived posts, search 'reliability' you'll find other links.Electrolytics can last longer if used routinely to allow them to reform. That means don't leave your device stored for months, turning it on for an hour or so monthly will do.For example, the Voyager deep space mission, launched in 1977, is still transmitting; its no better testament to good design and parts longevity.Sadly, chip makers know enough now to reduce manufacturing quality, to save on production costs. They target lifespans in the ~ 7 year range, creating a much bigger rift between consumer oriented chips and those for military aerospace.http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/40791/1/08-05.pdfThis is another reason to look more favorably on older gear, all 'solid state' from late 1960s through to ~ 2000 and to see gear built this century more skeptically.

author: sacherjj
author_rank: Frequent Contributor
timestamp: February 15, 2012, 04:46:41 pm
content: So in summary, saturation: They don't build 'em like they used to.

author: MarkS
author_rank: Unknown
timestamp: February 15, 2012, 04:56:04 pm
content: OK, what about ICs? If an IC was driven at its rated capacity and never overvolted or overclocked, how long would it last? I would assume that even under the best of circumstances silicon will break down over time.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 15, 2012, 05:43:43 pm
content: Quote from: MarkS on February 15, 2012, 04:56:04 pmMTTF analysis is the best anyone can do...that is, if you can get your hands on the data, which will necessarily vary between manufacturer, device, lot, etc.

author: ejeffrey
author_rank: Super Contributor
timestamp: February 15, 2012, 05:51:29 pm
content: Quote from: MarkS on February 15, 2012, 04:56:04 pmThat depends. Temperature is the big killer here. An IC that runs at near the maximum junction temperature will have a reduced life. A device that rapidly heats and cools frequently will also have problems with mechanical stress. A device that never runs hot should last essentially forever.

author: Unknown
author_rank: Unknown
timestamp: February 15, 2012, 06:17:16 pm
content: Quote from: saturation on February 15, 2012, 03:56:02 pmYou'll find some knowledgeable people, like Bob Pease and someone from Boeing he cites, argue that some parts of MIL-HDBK-217 are nonsense. For example, the idiotic idea that reliability doubles every time the operating temperature is decreased another X degrees. Bob argues that lowering the operating temperature of most semiconductors below 100°C or so hardly makes any difference. I haven't personally done any research, but Bob Pease had enough experience in this field to be a credible source.

author: saturation
author_rank: Super Contributor
timestamp: February 15, 2012, 09:20:33 pm
content: Yes, there is truth to that, but many of the constants in the book could just be theoretical or subject to sample error, so calculatedquantitativevalues are not accurate. What if the improvement was only 50% instead of double? Reliability folks do talk about the flaws in the standard. There are so many parts, and many interactions, even flaws in the model versus reality. Luckily the calculations are easy today, compared to when it was done by handand after all that effort, the results are just ball park rather than law.http://ieeexplore.ieee.org/search/freesrchabstract.jsp?tp=&arnumber=1677401&openedRefinements%3D*%26filter%3DAND%28NOT%284283010803%29%29%26searchField%3DSearch+All%26queryText%3Dderating+componentsNevertheless, while it could have been a purely theoretical or even faulty apriori at the outset, studies looking forward after establishing reliability practices do show the reliability is increased.http://www.nasa.gov/offices/oce/llis/0676.htmlSo, does the reliability of a component increase by Y for X degree of operating temp dropped, in any 'perfect' way? Not sure; it might be log or geometric or nothing until a threshold. But it can't hurt to play it coolI think folks still dedicate their lives studying this so the field still has much to discover.Quote from: alm on February 15, 2012, 06:17:16 pm

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 15, 2012, 09:54:14 pm
content: Quote from: alm on February 15, 2012, 06:17:16 pmI think the example you give is less idiotic and more oversimplification gone afoul; it sounds like erroneous interpolation based on a suggestion that reliability halves every time operating temperature is increased another X degrees, never mind applicability at the device vs system level. I feel like a large amount of emphasis is placed on operating temperature simply because it's one of the few factors that engineers can have reasonable control over.

author: saturation
author_rank: Super Contributor
timestamp: February 15, 2012, 09:57:27 pm
content: Yes, and its hard to rate parts equally because it depends on the construction of the part. BJT and such are good salvage, while 1980s memory chips and electrolytics are not [although those caps you could try to reform them, and see what happens!] Electronics used in low power sections are less likely to be worn out than those used in kV portions, like in analog oscilloscopes. Components used in designs were derating was used, are more likely to be salvageable, even in the kV range.Electronics aside, meal housings, knobs, and support hardware often cost more than the electronics parts these days, and are still clearly usable and are great salvage.Quote from: sacherjj on February 15, 2012, 04:46:41 pm

author: Unknown
author_rank: Unknown
timestamp: February 16, 2012, 09:57:04 am
content: Quote from: slateraptor on February 15, 2012, 09:54:14 pmYeah, it's probably true for example for electrolytics between something like 50°C and 105°C. The notion that it's a linear relation is strange to me, however, how are those electrolytics going to fare at sub-zero temperatures? Is the change from 50°C to 70°C the same as from 85°C to 105°C? Proper component-level failure analysis would require understanding the failure modes of each individual component. This will be different for large power transistors than for the small FETs in a modern CPU, for example. Mindlessly applying simplistic rules derived a long time ago (maybe the rule even originates from tubes?) to individual components will give misleading results.Quote from: slateraptor on February 15, 2012, 09:54:14 pmThat's probably true. It's easy to measure and often easy to decrease. Just put larger components or a more powerful fan in there.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: February 16, 2012, 10:08:22 am
content: How long do components last?Up until the point where you let all the smoke out.

author: saturation
author_rank: Super Contributor
timestamp: February 16, 2012, 02:15:34 pm
content: Here is the online calculator I had linked in another post.Choose your part, your operating parameters and it will model MTTF.http://www.sqconline.com/military-handbook-mil-hdbk-217-beta

author: Unknown
author_rank: Unknown
timestamp: February 16, 2012, 04:00:02 pm
content: They would do well to give the range in which the models are applicable. For example, a commercial electrolytic at 105°C has a predicted MTBF of 107hours (this sounds very high to me, since manufacturers often specify 1000-10000 hours), at 1000°C it's still 6000 hours, and in liquid nitrogen (-200°C) the MTBF is 4 * 1026hours, or longer than the age of the universe. I'm very skeptical if they can't even get the extremes right. They should be the easiest to model. At 1000°C the MTBF is approximately 0, and at -200°C it's similar, since the electrolyte will probably freeze and crack the capacitors.

author: PStevenson
author_rank: Regular Contributor
timestamp: February 16, 2012, 09:46:05 pm
content: electrolytics are just a "don't bother" for me I often salvage from boards, things like modems are good because people generally have bought their own and they give me the one the provider gives them for free, I have actually gained quite a collection of LD1117 regulators which are cool adjustable regulators.anyway just yesterday I was making an extractor fan for soldering, I built it into an old ATX powersupply case, I didn't want to bother with yet another thing that uses DC wall plugs so I built a little 7805 based power supply+transformer into it with a filter capacitor on the bridge. the filter capacitor was a large electrolytic, never used, philips but really old - probably 80s vintage. anyway I turned it on, all worked fine for about 10 minutes then I noticed the fan slowing down and then there was an almighty bang followed by a room full of smoke - it was the old electrolytic of course. I know there was no point in that story really, maybe you could take the fact it's not worth bothering with old electrolytics from it.it does always make me laugh when I see things like this on eBay (this was the exact type of capacitor too-mine was higher WV but basically the same otherwise)http://www.ebay.co.uk/itm/1x-NOS-MULLARD-PHILIPS-220uF-16V-ELECTROLYTIC-CAPACITOR-/320834734678?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4ab33d8a56

author: DrGeoff
author_rank: Frequent Contributor
timestamp: February 16, 2012, 09:56:34 pm
content: There have been problems with some Philips electro's before.Lookup Neve channel strips!

author: PStevenson
author_rank: Regular Contributor
timestamp: February 16, 2012, 10:03:50 pm
content: Quote from: DrGeoff on February 16, 2012, 09:56:34 pmbloody Neve channel strips are the bane of my existence! haha

author: saturation
author_rank: Super Contributor
timestamp: February 16, 2012, 10:34:53 pm
content: Yes, its is bizarre, but you might think of that website only as a calculator, so it's GIGO if the model values are unrealistic. They give you the formula and just save you the time of DIY; also the limit cutoffs as you said, are not included.But, life parameters reported by manufacturers are difficult to compare as they all use their own methods, thus the military example at least puts a common ground to make some relative comparisons.For example, here's a website with visible web data, this maker applies a different lifespan model to their capacitor data, and get large numbers similar to the military model. These are takeoff on their 'load life' or "endurance" data as their lifespan estimate.http://www.low-esr.com/endurance.asp#Solidhttp://www.niccomp.com/Catalog/nrsa.pdfIf we look at what few raw graphs are available on one of their types of caps, not its interpretation, the cutoff point is based on a slope deviation on certain cap parameters:http://www.niccomp.com/Catalog/nrsa.pdfNow compare it to a popular brand, Rubicon, and they use different methods to define 'endurance'. Choose any cap datasheet here.http://nichicon-us.com/english/products/alm_mini/pict_f.htmQuote from: alm on February 16, 2012, 04:00:02 pm

author: Blofeld
author_rank: Regular Contributor
timestamp: February 16, 2012, 10:44:02 pm
content: Quote from: MarkS on February 15, 2012, 04:56:04 pmThey don't really break down, but there's an effect called electromigration that might cause IC's to fail over time:http://en.wikipedia.org/wiki/ElectromigrationBut this happens only rarely.

author: saturation
author_rank: Super Contributor
timestamp: February 16, 2012, 10:52:52 pm
content: If you find an old electrolytic, or any of questionable age, it may pay to reform it before using it. If it fails, it at least won't bang at full load as you can reject it if it fails, but if it doesn't it will be ~ new.http://www.everyspec.com/MIL-HDBK/MIL-HDBK+%281000+-+1299%29/MIL-HDBK-1131B_28461/Instead of the lamp limiting resistor, all you need to do this is a variable PSU with constant current capability.Quote from: PStevenson on February 16, 2012, 09:46:05 pm

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 17, 2012, 02:12:41 am
content: Quote from: alm on February 16, 2012, 04:00:02 pmCorrect me if I'm wrong, but it almost sounds like you're confusing MTBF with serviceable lifetime.It's to my understanding that to use MTBF or any other reliability measure as an absolute gauge is improper practice; are they not intended as a tool to aid engineers in narrowing their focus down to a particularly susceptible sub-section of a complicated system for the sake of design improvement, viz. what significance does MTBF of a single component have if not considered with respect to other components within the same system?

author: amyk
author_rank: Super Contributor
timestamp: February 17, 2012, 10:11:49 am
content: Quote from: Blofeld on February 16, 2012, 10:44:02 pmWith CPU feature sizes becoming smaller and smaller (and corresponding increases in current density), electromigration may become more significant. This is just speculation, but the latest processors might not last as long because of this -- only long enough to meet their "designed lifetime".

author: vk6zgo
author_rank: Super Contributor
timestamp: February 18, 2012, 03:24:54 am
content: Quote from: slateraptor on February 15, 2012, 07:40:21 amSorry!I wrote an answer a couple of days back,but was distracted by the phone,& didn't post it!No,I don't know for sure whether they still use the spiral cutting process.The inductance problem which we measured was well known in the early days of carbon film resistors,which is why most high frequency equipment used carbon composition resistors.I have never heard any reference to the problem with modern film resistors,so I assumed that there is a different process.After all,there would have to be one for SMD film resistors.

author: Unknown
author_rank: Unknown
timestamp: February 18, 2012, 12:05:34 pm
content: Those 'One Hung Low' brand 1/4 W metal film resistors still had the spiral cut, last time I checked (a few years ago). It's only a few turns so it's only an issue for low value resistors in the hundreds of MHz range. You typically wouldn't use through hole components for 1 GHz frequencies these days anyway. I believe carbon comps have their own issues at higher freqs. Due to their construction they have a fair amount of parasitic capacitance.

author: saturation
author_rank: Super Contributor
timestamp: February 18, 2012, 01:50:01 pm
content: Yes, if a process of high density fabrication is used on all ICs, including older designs that are reissued, then much larger ICs, such as DIP, are simply just packaging: its a denser and smaller wafer inside a large package, and could suffer the same reduction in reliability. Its a reason the NASA paper I linked has interesting ideas on testing and estimating updated life tables for newer devices.Quote from: amyk on February 17, 2012, 10:11:49 am

author: vk6zgo
author_rank: Super Contributor
timestamp: February 18, 2012, 02:33:42 pm
content: Quote from: alm on February 18, 2012, 12:05:34 pmThey were frequently used in TV tuners up to quite recently at hundreds of MHz.Tuned circuits in these devices are "only a few turns"!But you're right,most of the time,you would be using SMD components,although these aren't perfect either,when you combine UHF & high power ratings.High power SMD resistors are quite big,so the parasitic capacitance thing rears its head again,though thankfully,most high power SMD "Rs" are low value anyway ,so the effect of the parasitic C is minimised.

author: Unknown
author_rank: Unknown
timestamp: February 18, 2012, 02:52:17 pm
content: I once estimated the inductance of metal film resistors due to the serpent pattern to be something like 7 nH for a 50 ohm resistor that I had on hand and 26 nH for a 1 Mohm resistor (based on the number of turns and dimensions). The 7 nH might be an issue if your frequencies are above ~500 MHz. 26 nH in series with 1 Mohm is unlikely to be an issue.SMD resistors tend to be much better, if only for the much lower lead inductance. Of course outside a SPICE simulation no component is ideal.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 18, 2012, 03:04:32 pm
content: The old Philips beasties started to show significant inductive reactance at around 50MHz,but they were physically bigger resistors,& probably had more turns.This WAS back in the dark ages!

author: jahonen
author_rank: Super Contributor
timestamp: February 18, 2012, 03:55:04 pm
content: Somewhat related interest, I got recently some carbon composite resistors to try them out on 1k probe just because I suspect that mentioned spiral is a drawback on modern resistors. Other than potentially interesting high-frequency properties, they are absolutely horrible for anything else.First impression was that they might be somewhat better for 1k probe, but not with huge difference. I think that construction is more important than the resistor used. I have to experiment more with them.Regards,Janne

author: Unknown
author_rank: Unknown
timestamp: February 18, 2012, 04:28:24 pm
content: I believe Doug Smith uses a 1206 resistor in his 1 GHz passive probe design, maybe for this reason? Howard Johnson suggestion was not to use carbon film, but use metal film, a suggestion that I didn't quite understand, are carbon film much worse in the HF department? Of course they suck in every other regard, kind of like carbon composition.The idea that carbon composition is better for high frequency may be from the time that common resistors were wirewound, which are of course horrible for high frequency unless you get the special ones with Ayrton-Perry winding.From RF Circuit Design (2nd. ed), by Christopher Bowick et al:QuoteHe cites Handbook of Components for Electronics, McGraw-Hill as source for Fig. 1-4. No mention of inductance due to the helical cut, which I would expect to dominate over lead inductance.Leslie Green in his excellent book ANALOG SEEKrets (see other thread for download links) states that bulk composition resistors of any type are not very good above 10 MHz because of skin effect losses. This is of course much less an issue for film resistors. He states that thin film chip resistors are quite good, that MELF resistors (he ignores leaded resistors for VHF) have a variable parasitic inductance due to the spiral cut pattern, and that some micro-MELF resistors have a special pattern (a laser cut helix with large caps) that makes them good up to 10 GHz. Some of the small chip resistors are even better.I didn't find a recent source claiming that carbon comps are good for high frequency.

author: Zero999
author_rank: Super Contributor
timestamp: February 18, 2012, 06:36:03 pm
content: Quote from: saturation on February 15, 2012, 03:56:02 pmIt probably won't use electrolytic capacitors which are not normally permitted in high reliability designs.

author: Unknown
author_rank: Unknown
timestamp: February 18, 2012, 07:21:48 pm
content: Were they allowed to use tantalum electrolytics? I seem to remember the military not being too keen on the rather violent failure mode of tantalum capacitors, but they tend to be much more reliable and much better at extreme temps than aluminum electrolytics as long as you derate their voltage and limit their dI/dt.

author: saturation
author_rank: Super Contributor
timestamp: February 18, 2012, 09:22:46 pm
content: I recall alms view both for military and space applications in substituting suitable tantalum for electrolytics. As the OP original query involved "all" types of components, my reply was equally mixed, sorry to be confusing. There are some interesting reports of electrolytics used in support electronics in nuclear power station, and they have a good track record of reliability if suitably derated and monitored.http://digital.library.unt.edu/ark:/67531/metadc3104/Not sure if non-tantalum electrolytics are banned or space not, but the cubesat project uses COTS components to allow university projects to launch into space.http://en.wikipedia.org/wiki/CubeSatQuote from: Hero999 on February 18, 2012, 06:36:03 pm

author: DaveW
author_rank: Frequent Contributor
timestamp: February 18, 2012, 09:50:27 pm
content: Quote from: alm on February 18, 2012, 07:21:48 pmWe're allowed to use them in mil aerospace if we derate the voltage rather severly, stay away from the extremes of the temperature rating and quantify the worst case ripple. Although for the bulk decoupling, sprinkling lots of ceramic caps around seems to be replacing them somewhat

author: vk6zgo
author_rank: Super Contributor
timestamp: February 19, 2012, 02:53:53 am
content: "The idea that carbon composition is better for high frequency may be from the time that common resistors were wirewound, which are of course horrible for high frequency unless you get the special ones with Ayrton-Perry winding."That would have been around 1913?It doesn't matter how wirewound resistors are wound,they all have excessive inductance for High Frequency use,unless external correction components are used to cancel this effect.This is maybe viable for a MF Test load,but for normal use in everyday circuits it would be ridiculous,so common resistors from the earliest days of valve Radiowerecarbon composition.Carbon composition resistors were "the only game in town" up until the late 1950s,when the first carbon film resistors became available for general use.As I pointed out earlier,these DID have excessive inductance.There is a lot of pontification on the 'Net & in Technical publications by people who are very smart,but have very little idea of history.

author: gregariz
author_rank: Frequent Contributor
timestamp: February 19, 2012, 03:44:16 am
content: Now you made me pick up my (1st edition) copy of Bowick and find the curves comparing composition and film resistors.Bowick is an excellent book (perhaps one for the best) but I think he maybe should have reworded that section. After reading it he kind of left me with the impression that Carbon composition resistors were worse than wirewound resistors, although he didnt actually say that. Which of course is not true. No one would use wirewound resistors in place of a composition resistor at HF.With regards to the special inductance cancelling winding (Ayrton Perry winding) for a wirewound resistor. Maybe I am not old enough but I cannot recall having ever seen them available. I suspect they date from the period before composition resistors were commonly available. Terman talked about them in his handbook c~1939.If you have a copy of Bill Orr's radio handbook he also gives curves for both composition and wirewounds, and of course wirewounds are poorer.With regard to the newer film resistors I have used them for things like attenuator pads up to VHF with no problems. At microwave I use smt thick film resistors for the same purpose up to a couple of GHz without problems.

author: slateraptor
author_rank: Frequent Contributor
timestamp: February 19, 2012, 03:45:30 am
content: Bob Pease wrote of special "type HS" (HS presumably meaning high speed) wirewound resistors that were well suited for high frequency applications of the time; this was as late as 1991. Although not explicitly mentioned, that Ayrton-Perry winding scheme may have been what he was alluding to.

author: Zero999
author_rank: Super Contributor
timestamp: February 19, 2012, 12:38:32 pm
content: Quote from: vk6zgo on February 19, 2012, 02:53:53 amIt's possible to specially wind resistors to have a very low inductance. Two windings, each wound in opposite directions are used for high frequency wire wound resistors.

author: Unknown
author_rank: Unknown
timestamp: February 19, 2012, 01:45:39 pm
content: Quote from: vk6zgo on February 19, 2012, 02:53:53 amBifilar winding can reduce inductance, and I believe Ayrton-Perry winding was designed to minimize both capacitance and inductance.Ohmite claims< 1nH at 1 MHz, no idea about capacitance.Quote from: vk6zgo on February 19, 2012, 02:53:53 amMaybe early carbon film resistors did have higher inductance? More 'windings'?Quote from: gregariz on February 19, 2012, 03:44:16 amHe probably considered it obvious that no one would use a normal (non-bifilar) wirewound resistors for HF. It wasn't really about wirewound versus composition for me however, but whether composition was better than film. Carbon composition is often assumed to be better than metal film for HF, since a metal film resistor looks essentially like a small inductor. This doesn't appear to be the case, however.Quote from: gregariz on February 19, 2012, 03:44:16 amThey are currently available from Digikey, for exampleWNA51RFECT-ND. They are quite expensive, though. I would agree that they're now much less important than in 1939, since we have several other options that are good for high frequency.