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The prices of components of supposedly the same type and with the same parameters vary strongly between manufacturers.

Assuming my use does not come close to the absolute maximum ratings, is it worth paying extra for more expensive brands, or do the cheaper brands perform just as well? Or can I get bitten by subtle differences between manufacturers?

Does this also depend on component type? For example: resistors (with the same specs) might all perform equally, but 78xx regulator quality varies strongly, etc.

One thing I did notice (and do value) is that with the more expensive brands, the quality of the datasheets is usually much better. But mainly, I'd gladly pay the higher price if it means I can avoid hunting for subtle bugs I'm most probably not experienced enough to find anyway.

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I know of no hard rules that apply to the range of products you're asking about. Additionally, the subtleties you're asking about probably only come in to play if you're trying to use a part near its limits or in some other extreme use case. Otherwise it's true that (274Ω 1% 0603 Mfg A) == (274Ω 1% 0603 Mfg B) –  Samuel Jun 22 at 20:00
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Electrolytic caps are well known for quality varying with price (and brand). –  jippie Jun 22 at 20:22
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Are more expensive parts worth what? Once you've answered that, you've answered your own question. –  EJP Jun 23 at 12:49
    
EJP's comment deserves all the votes! –  John U Jun 23 at 17:58

4 Answers 4

You can never judge a book by its cover - especially in electronics.

"Cheaper" parts sometimes work perfectly in an application. Sometimes they don't. Expensive parts may have just as many irregularities and variations as cheap ones - sometimes even nastier ones.

You can never trust any part in your design until you (1) fully quantify what parameters your design are sensitive to (2) fully qualify whichever parts you intend to use, and (3) come up with some contingencies when assumptions made in (1) and (2) fall apart.

Also, you can never really trust a datasheet 100% - it's never a substitute for proper validation. Many parameters in the datasheet are artificial, in that they're generally measured at 25°C at some test condition (voltage, current) that makes the part look favourable. I've seen 30-page datasheets and 3-page datasheets in my day. Can I say up front which is 'better'? Not always.

Whichever parts you use, make sure that the manufacturer has some field application engineering (FAE) people or a help contact so that if you do come across some weirdness, you may be able to get some assistance with mitigation.

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+1 - never substitute claims for proof –  slebetman Jun 23 at 4:04
    
"FAE" as in "Failure Analysis Engineer"? –  romkyns Jun 25 at 0:53
    
Field application engineer. Updated the answer. –  Adam Lawrence Jul 6 at 22:04

Any reputable manufacturer should provide parts that meet or exceed the guaranteed specifications they state. If you design within the guaranteed specifications for that manufacturer (which may be the same for several makers), it should not matter which brand you buy.

If the parts are counterfeit or are not from a reputable source, you could have problems.

If you design to "typical" specifications or characteristics that are not stated (for example noise level or temperature coefficient of input offset voltage in a low cost op-amp) you could see differences between manufacturers or between lots from the same manufacturer. I've seen noise levels vary by a factor of 5:1 between the same parts from the same manufacturer. Unless you're willing to characterize the parts yourself (expensive and time consuming) this can be a problem.

I would say it is more important to make sure that the characteristics that are important to you are guaranteed, which may mean switching to a more expensive part at the same or a different manufacturer.

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Results are very variable.
Be sure to distinguish between high cost suppliers and high cost brands.

"Provenance" is a major factor.
If you can trust the manufacturer AND the distribution channel then you probably know what you are getting an can decide if it suits you.
If you cannot trust BOTH of these you have no certainty that what you get is good BUT a reasonable expectation that it is not.

Components supplied by reputable manufacturers own outlets are trustable
(at least often enough that only paranoia will save you if they get it wrong)

Components sourced by reputable suppliers are almost always trustable.
eg if you see a brand offered by eg Digikey you can expect that versions sold by them probably are from the manufacturer claimed and probably have a data sheet and probably meet datasheet specs. You can also expect to be able to buy many of the same genuine products elsewhere for somewhat less than they charged, and apparently genuine but actually fake products elsewhere at unknown prices.

Buying Panasonic parts is always a good idea and they are often not much dearer.
I have no business relationship with Panasonic except as a satisfied customer.
They make a wide range of products and seem to know what it takes to make quality product - and then choose to do so.

(Wet aluminum) Electrolytic capacitors are useful products with well defined designable lifetimes IF you can rely on their specifications. From "unknown name" manufacturers I have seen "105C rated" caps that were poor examples at any temperature and others which you know are not up to spec just by looking at them. Others are not so obvious.

A significant percentage of Asian electrolytic capacitors are low spec and data sheets are rubbish (based on my having used many hundreds of thousands of ecaps in designs made in China and so having looked carefully at what is offered.) You can get some entirely acceptable ecaps from Asia - but if you are buying directly from Asian suppliers you must be aware of possibilities. This only applies to volume production. For small quantities rely mainly on a reputable supply channel having been vigilant for you.

A failed 0.1 cent resistor can destroy a product.
1% resistors from reputable suppliers in modest volumes cost so little that insertion costs predominate. Buying from sources where you are not aware of provenance makes no sense at all.

If you find a product frm an unknown manufacturer and you are uncertain about the supply chain and there IS a datasheet but it leaves you in doubt - then quite often it can be useful (end enlightening) to take a "likely unique" phrase from the data sheet and do a web search for it. If ALL examples are from the manufacturer concerned it tells you little. BUT often enough I have found that chosen phrases turn up in a range of data sheets fro related or even quite different products from quite unrelated manufacturers.
If you get a technically highly competent sounding comment in an apparently less than top-class data sheet you will often find that it has been "mined" from the data sheets of a top class manufacturer. At one stage I did quite a lot of this sort of searching and found that such copying was common enough from suspect specification manufacturers to make the searching worth doing. [I often did this because a manufacturer named a given brand part that they intended to use and I wished to demonstrate the desirability of using the parts and brands that I had specified. Saying "just do it" may work, but being bale to say "because ..." as well may some times help. Sometimes.]

Unlikely but apparently true from what I've seen :-) : LiIon batteries with "Fire" in the brand name may perhaps be OK from genuine makers but seem to attract cloners who wish to claim ver higher (often impossible) mAh ratings. [Ultrafire, EverFire, SureFire, ... :-)]

Small user replaceable batteries (eg AA C D) can usually be checked by their weight. A light for spec battery is always fake. An OK weight battery may be fake - but probably will be OK. Any AA Alkaline or NimH under 25 grams should be looked at with care. Any AA claiming over about 2700 mAh similarly. 18650 LiIon cells claiming over about 2300 mAh - look carefully. 2500 mAh may be possible. You can get 18650's labelled as 3000 3500 and 4000 mAh capacity - walk away ... .
The majority of smaller Alkaline and NimH cells come from 3 major Chinese manufacturers. Two usually do not sell retail versions under their own names. GP or GoldPeak do - and they are good enough that there are many fake/counterfeit imitations on the market with their labelling. I have seen Sony branded batteries whose labelling and packing pass very close inspection - but whose weight instantly marks them as fake.

FWIW - semiconductor components made by Chinese manufacturer LRC (Leshan Radio Company) that have a specification the same as OnSemi parts are (in my experience) trustable and essentially identical. LRC and OnSemi at one stage had a joint venture operation. Whether this is still in force I know not but their product seems solid - mainly older tech parts.

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Would the phantom downvoter care to explain the reason for the vote. I can stand the 0.0145% reduction in my "rep" and am happy (genuinely) if someone can usefully correct anything I've written. It would be more useful, I think, if people were to make relevant comments than anonymous votes. My concern is that such behaviour reduces the visibility of the answer to others, and it contains relevant and useful material. The decision re paying more or less is very much affected by the factors that I mentioned - so I'm at a loss as to the assessment. Assuming the downvote was assessment based. –  Russell McMahon Jun 23 at 11:16
    
I was wondering about that as well... I found your reply very informative. –  Duoran Jun 23 at 22:50

is it worth paying extra for more expensive brands, or do the cheaper brands perform just as well?

Well, what's the cost of failure? Human lives? In that case, I'd spend a fair amount more to be sure I've got top quality. It's a $9.95 disposable toy? Go with the cheapest stuff that isn't of such obviously poor quality that it will have a high failure rate. In-between? That's engineering judgment. How much are you going to save on components, versus how much will you have to pay out in warranty claims or even in lawsuits? Be careful not to "Pinto" yourself!

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