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This is something that has bothered me for ages. I wasn't sure it could be made up as a question here, until Olin Lathrop suggested it to me in a comment to another thread.

We all know what we are talking about when someone mentions, for example, an 1N4007 or 1N4148 diode. The first is a general purpose rectifier with 1A max forward current and 1000V max reverse voltage, just to be explicit. And this information is completely independent from the manufacturer of the specimen we have at hand (I'll bet anyone with a bit of experience in EE would go crazy if he saw, say, a DIAC labeled as 1N4007 produced by a reputable manufacturer).

So we know there are "standard" part numbers which corresponds to devices with well-known characteristics. As Olin pointed out in that answer to the question in the thread I mentioned above, although we all know what a standard part is, sometimes different manufacturers give slightly different specs for the same part. Still, an 1N4007 is an 1N4007, this little differences notwithstanding!

So my question is, what defines what a standard part actually is? Historical reasons (the first manufacturer got the part number; second sourcing the part to others made that part a de-facto standard)? Industrial agreements (some manufacturers decided it would be good not to do cutthroat competition on low-tech parts, so they decided to standardize)? Official standardization organizations (Olin mentioned JEDEC in that comment; may it be some other institution as well)?

To really gild the lily the answer should also provide references to possible official documentation about common parts or procedures (if they exist) to standardize a part.

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  • \$\begingroup\$ Hah. I was going to post this question a few days ago, exactly because of the same comment. Too bad I didn't, it has potential to become popular! \$\endgroup\$
    – pipe
    Jul 20, 2016 at 20:59
  • \$\begingroup\$ A DIAC would at least be 3N... or 4N... though, having more PN-junctions. \$\endgroup\$
    – pipe
    Jul 20, 2016 at 21:02
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    \$\begingroup\$ A standard (i.e. a document) defines what a standard part actually is. Strictly speaking, 1N4007 and 1N4148 are popular parts, rather than standard parts. (Unless there is a standard which defines what a 1N4007 and 1N4148 should be. I'm not aware of such a document, though.) There is a [marketing?] term "industry standard". Somebody came out with a good product or a concept. It got reverse-engineered and knocked-off a lot by other entities. So, in effect, there exists a kind of an unwritten standard. Don't confuse industry standard with proper standard. \$\endgroup\$ Jul 20, 2016 at 21:02
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    \$\begingroup\$ I think the term "jellybean" captures the ill-defined notion a bit better. \$\endgroup\$ Jul 20, 2016 at 21:31
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    \$\begingroup\$ @Nick: I think the 1N and 2N parts are more than just a designation picked by one manufacturer, then copied by others due to popularity. I vaguely remember something about Jedec being envolved, but I'm hazy about it, so not writing a answer. Other parts, like the LM324 opamp are as you describe. That was first created by National, then copied by various manufacturers. \$\endgroup\$ Jul 20, 2016 at 21:33

3 Answers 3

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The "1N4007" and "1N4148" part numbers are JEDEC standards, and presumably there is a standard document available from http://www.jedec.org.
After some hunting, this organization claims to be able to supply a print or PDF copy: https://global.ihs.com/doc_detail.cfm?&input_search_filter=JEDEC&item_s_key=00207654&item_key_date=290303&input_doc_number=1N4001&input_doc_title=&org_code=JEDEC

Most manufacturers parts are defined better by the manufacturer (finish, lead length, marking, packaging) so it is rare that a designer will refer to the original standard rather than the manufacturer's current data sheet. A requirement for lead-free finish on the wires was NOT part of the old 1N4007 spec, but can be very important nowadays. So, too, can feed belt packaging versus box-of-loose-parts.

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  • \$\begingroup\$ Searching for 1N4007 on that site gave me no results. Care to add a direct link to those standards? \$\endgroup\$ Jul 20, 2016 at 21:40
  • \$\begingroup\$ I think your answer is on-track, but missing much detail. The 'lead-free' issue ties in with RoHS standards, etc. A purchasing agent is often given a list from the chief engineer of preferred #1, preferred #2, acceptable, and not acceptable parts. There are popular parts for hobbyist and some manufacturing plants may use them. Then there are 'trusted' parts, and 'mil-spec' parts. This rabbits hole goes very deep. \$\endgroup\$
    – user105652
    Jul 20, 2016 at 21:48
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    \$\begingroup\$ @Lorenzo Donati: The "1N4007" part is subsumed in a spec for "1N4001 -1N4007" all in one document. I've added a pointer to a pay-for source. \$\endgroup\$
    – Whit3rd
    Jul 20, 2016 at 23:13
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    \$\begingroup\$ JEDEC type registrations are not available on the web; you have to contact someone to get a (paper?) copy. \$\endgroup\$
    – CL.
    Jul 21, 2016 at 6:54
  • \$\begingroup\$ Yes, I can confirm the 1N400X standard offered by IHS is legitimate, as I was able to download it after payment. Fresh document from 1963. Interestingly, even it says "reproduction prohibited", it's likely that its copyright, (also other documents from the same era) has long expired and can be freely reposted online! But more information is needed to determine the copyright status. Does anyone know in which form that the original "Electron Device Type Registration Release" was published? If there is a new registration, how did JEDEC publish it? In a journal? newsletter? on demand? or what? \$\endgroup\$ Jan 21, 2020 at 18:11
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Historically, standards were used by the US military to set the requirements of various parts but vendors are free to implement a part in any way they choose provide the required performance is achieved. Note that the overall performance can vary widely; the key is "does it do what this test requires"?

There is a specification finder for 'standard' microcircuits, but beware: these specifications have holes large enough to drive a very large truck through. I have been bitten by this when trying to source an ADC to replace a very obsolete part and it did not operate the same way in my application as the original part (an X-ray showed the die had different dimensions).

Most microcircuits are defined within MIL-STD-1562 (warning - paid for at this link).

All the specifications are here.

To put these numbers on a part, vendors need to apply the specific tests required.

Capacitors can be to many specifications such as CECC30801-x and MIL-PRF-55365 (it is a long list).

Likewise, resistors can be to a number of standards such as CECC40401-x or perhaps to MIL-PRF-55342-x

Industry standard parts are more correctly known as popular parts that happen to be in very wide use; a few decades ago, the 'standard' general purpose op-amp was the venerable 741, but it would an unlikely candidate for a new design.

Fortunately, many op-amp footprints are now compatible across many parts (particularly in SOIC for single, duals and quads for ordinary parts - no special features such as shutdown and so on).

Likewise, we have standard footprints as answered at this question and although there is little enforcement, it is in the interest of vendors to follow this guidance.

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There are at least two types of standard, with one or two slightly grey levels in between as a part slowly gets promoted from the less to the more official.

There are many official industry standards, documents produced by organisations like JEDEC, IEEE, 3GPP etc, that define the parts.

Then there are de facto standards. These are neither officially documented, nor created for the purpose, but just happen, because I don't need to use an extra parts bin for half-amp diodes if 1N4007s are cheap enough, and enough other people think the same way.

What is a 'standard' changes as time marches on. 30 years ago, leaded E12 resistors, and the BC109 were 'standard', whereas today surface mount E24 resistors and perhaps the ULN2803 are. It also varies strongly by engineering sector.

What's the most 'standard' component? I'd vote the 10k 1% resistor ;-)

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    \$\begingroup\$ Component names with the "1N" and "2N" prefixes are JEDEC standards. "BC*" (along with "BD*", "BF*" and so on) and "UL*" are names standardised by the European Electronic Component Manufacturers Association (FWIW: "B" at the beginning of the code signifies a silicon device, whereas "U" is an integrated circuit; "C" is a small signal transistor, "D" is a power transistor, "F" a radio frequency signal transistor, and "L" a radio frequency power transistor; the rest of each code is simply a sequence number) \$\endgroup\$
    – Jules
    Jul 12, 2018 at 14:26

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