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I put in an order for 50 Nexperia 74HC173D,652 with JLCPCB for some kits I'm having built and assembled by them. These are going into electronics kits that are sold to high schoolers as part of a digital electronics curriculum, so there are no automotive or military requirements.

The supplier sent me an email this morning stating

C546651 you requested to purchase belongs to a batch that was produced in 2016.

May I know if it is acceptable for you? If yes, we will help to proceed further.

Do folks think this is an issue assuming it is coming from a reputable distributor such as Mouser, Digikey, Verical, etc., or should I run from this?

JRE
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Kevin McQuown
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    Can you edit your question (don't post new info in comments) and add how many you're building, what they're for, safety/reliability requirements and much more. Without knowing that, answers must be guesswork or opinions and the question could get closed. Lots of info about the application, please. – TonyM Nov 22 '23 at 14:09
  • Depends on your application! For general stuff: No, not really.... 7years is not a lot for ICs. Automotie, aerospace, etc.... You really want to buy your parts from a company which gets the "cheapest available at Schenzen market today!"? Different storys for prototypes, but for sale.... run from it. – ElectronicsStudent Nov 22 '23 at 14:26
  • Old leads can have solderability problems if they've not been stored properly. The silicon inside ought to be OK, regardless of date. – Neil_UK Nov 22 '23 at 14:27
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    I'm still using chips I bought from Maplin and Watford Electronics (both UK) in the late 1970s! These are only for one-off home projects but I don't remember finding a dud. – Transistor Nov 22 '23 at 14:36
  • I updated my question to include data on it's application. – Kevin McQuown Nov 22 '23 at 15:24
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    @ElectronicsStudent, each of your repeated exclamation marks reads as shouting and angry. Your comments would express themselves much better without them. – TonyM Nov 22 '23 at 15:46
  • Long shot: They may refer to an open spool from 2016, at which point hand soldering would not be an issue but hot air or wave soldering would require baking. 74HC has been in production for a long time so it's unlikely there would be a die shrink since 2016 which would affect your circuit even if you mix it with 2023 parts. – winny Nov 22 '23 at 16:03
  • @Transistor, "I'm still using chips I bought...in the late 1970s" Yes but they were very probably new or near-enough when you bought them. The question's not 'can very old ICs be used', it's 'why am I being sold old ICs instead of new ICs'. (Which I'd guess are part of an old batch that they want to get rid of.) – TonyM Nov 22 '23 at 16:19
  • Is there any reason why you want the tube packaging (652)? You may get newer stock if you accept other packaging types. – Paul Nov 23 '23 at 10:18
  • @Transistor: Many kinds of parts manufactured in the 1970s would almost always have their legs coated in a small quantity of an alloy with a significant concentration of lead. Many alloys containing tin have a tendency to crystalize, but lead is very effective at curtailing this tendency. – supercat Nov 23 '23 at 16:04

2 Answers2

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Short answer: This is fine, just let them assemble the PCBs with those parts. There won't be any noticeably elevated defect rate. (You'll still have to expect that there can be one or two defective boards in the batch, for all kinds of reasons.)

Long answer: It depends on the part and its package.

In general, solid-state devices have practically infinite shelf life. They're solid-state after all, which means that there are no moving parts and no liquids that could dry out. They're essentially just "fancy rocks" - the atoms within them are bound in solid crystal lattices and aren't going anywhere as long as they're not in an environment that degrades them chemically (i.e. acidic or basic conditions).

Another aspect to a part's shelf life is its package. Very fine pitch SMD packages, especially BGA, can accumulate moisture in the bonds between their metal leadframe / substrate and polymer encapsulant. When you then heat them up in a soldering oven, the moisture suddenly turns into steam and essentially explodes the package from the inside. This is called "popcorning".

Your SOIC packages, on the other hand, are so large and simple in comparison to modern BGAs that popcorning in them is practically unheard of. You could ask JLCPCB to bake the old parts as a precaution if you're still worried about this. Baking (i.e. 24 hours at 110°C for your SOIC parts) is the industry standard procedure for drying parts before soldering if they might have absorbed moisture during storage.

You have to keep in mind that there are distributors that specialize in stocking old and discontinued parts, like Rochester - if silicon chips rotted in storage, they wouldn't be in business.

Non-solid-state parts are different, of course - I wouldn't want to use electrolytic capacitors that are a decade old for a production run, for example. (Ceramic caps, on the other hand, are fine even when they're quite old.)

Jonathan S.
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    This is a great answer. I would add also that you should be wary of new old stock for electromechanical parts, such as relays. Ask me how I know... – Vladimir Cravero Nov 23 '23 at 10:23
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NXP's standard is 5 years, and they can sit around their customer for another year after that. There is no real shelf life concern with semiconductors like that, just solderability. If properly stored most parts will remain reasonably solderable for 20+ years in my experience.

On the other hand, according to an EEVBLOG posting, Digikey have refused return of electrolytic capacitors that are already 7.5 or 8 years old. Aluminum electrolytic capacitors, even if stored in a good (cool dry) environment do eventually dry out, so that's a chunk taken out of their useful life.

It sounds like JLC (presumably through their sister distribution company LCSC) are being proactive. In mass production a part that's a bit less solderable could result in lower yields and rework. In one-off kit assembly, it's just a bit more time with the soldering iron and maybe the joint doesn't look quite as wonderful.

I would have zero concerns myself on the basis of age (of this general magnitude), and find them proactively broaching the issue refreshing. LCSC seem to be a good company, even if their prices are sometimes higher than others in the China market. Of course the manufacturers they carry sometimes offer parts that may not be what you expect, so always read the actual datasheets for the specific manufacturer. In this case, it's Nexperia so no worries.

Spehro Pefhany
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    There are many things that can go wrong in the manufacture of a board. If using six-year-old parts increases the likelihood of failures by a ten-parts-per-million, someone who worked hard to reduce failures from all other sources below one part per million would likely view that as unacceptable, but someone whose processes were cruder and expected a 1% failure rate wouldn't even notice something that increased the failure rate by 10ppm. – supercat Nov 23 '23 at 17:37