mosfet shipped only in static-dissipative bag...ok ? - Page 1
Forum section: electronics / general

author: subliti
author_rank: Contributor
timestamp: November 13, 2019, 07:31:44 pm
content: HeySo i ordered a bunch of passiv stuff and also some mosfets. Most of the stuff came in normal ldpe ziplock bags. The mosfets came in what it seems a pink/blue static-dissipative bag only, no foam around the legs. This doesnt feel right to me. I have no doubt they work, but still no one knows if they are damaged. So i wanted to ask about opinions. Should i ask for refund/return them ?Shouldnt they be shipped in a shielded bag ? What about the static fields generated from the normal ziplock bags or from outside, a static-dissipative bag cant protect from that, right ?

author: Yansi
author_rank: Super Contributor
timestamp: November 13, 2019, 08:28:45 pm
content: Have you ever seen a 48 piece plastic tube, that carries TO220 packages? That one is probably not even dissipative and noone complains.

author: wraper
author_rank: Unknown
timestamp: November 13, 2019, 08:56:57 pm
content: If all of it was in outer static shielding bag or box, it's OK. If you ordered at place like ebay or aliexpress, you should be thankful for even getting static dissipative bag.

author: subliti
author_rank: Contributor
timestamp: November 14, 2019, 08:18:26 pm
content: Quote from: Yansi on November 13, 2019, 08:28:45 pmAfaik if you buy them from a reputable distributor then they should be 100% dissipative.Quote from: wraper on November 13, 2019, 08:56:57 pmNo there was no static shielding bag. Just the mosfets in the dissipative bag and tossed together with the other stuff in normal ldpe bags.So i wanted to ask if this is ok, i think its not, because without a metalized shielding bag the outer static fields can penetrate the dissipative bag and damage the components. Or am i wrong ?

author: wraper
author_rank: Unknown
timestamp: November 14, 2019, 08:23:01 pm
content: Quote from: subliti on November 14, 2019, 08:18:26 pmIf it's from a big respectable distributor like Mouser or Digikey, it's not OK. If it's from some shadier place, be happy it's not in plastic wrap.

author: james_s
author_rank: Super Contributor
timestamp: November 14, 2019, 08:41:50 pm
content: It's not ideal but I would not really worry about it either unless they're going into some kind of safety critical application. I've had random power mosfets laying around many times and have not had one show signs of damage yet. Sure it's possible they have sustained damage that could reduce reliability but nothing has been apparent. Sensitive low power stuff is another matter, I've had RF signal FETs damaged by ESD.

author: magic
author_rank: Super Contributor
timestamp: November 14, 2019, 08:48:36 pm
content: My local electronics store has the employees walking on carpets, picking up FETs from boxes on the shelves with their bare hands and stuffing them into ziplock bags for the customer.I figure it must be working for them. They are in business for over 20 years and used to supply all the electronics repairmen in the city back in the glory days of analog TV.

author: subliti
author_rank: Contributor
timestamp: November 14, 2019, 08:59:24 pm
content: Quote from: magic on November 14, 2019, 08:48:36 pmTrue, i also saw this at Conrad. And that was the time i decided i will never buy active/and/or esd sensitive components from them anymore. I guess this practice works because in local shops like that mostly ordinary people buy their stuff to tinker around or change a switch and things like that. And if it also works for the electronics repairmen in the city, then because the device did not fail immediately, but no one can proof month later why something failed.Quote from: james_s on November 14, 2019, 08:41:50 pmNo, nothing like that, but i paid some bucks believing to get good original properly packaged mosfets where i can be sure everything is ok.I guess i will point this issue out and see..

author: Yansi
author_rank: Super Contributor
timestamp: November 21, 2019, 10:58:29 am
content: Sorry for digging this thread up, but lookie what I've just got!I think they will be fine anyway. MOSFETs are usually shipped in the clear plastic tubes, that are no deal better than this.

author: rsjsouza
author_rank: Super Contributor
timestamp: November 21, 2019, 11:35:52 am
content: In the old days the rule used to be that anything bipolar (74 TTL series, Linear, BJTs, UJTs, JFETs, diodes) did not require antistatic shielding at all and the only ones that were carefully shielded were the CD4000 CMOS parts (and later the 74HC). We all went our merry way without really knowing if a failure could have been caused by static or not.Nowadays, after seeing some failures caused by static and other failures happen completely without explanation, I am much more conservative and tend to treat parts with a higher level of care. After all, static discharges can either damage or weaken the parts depending on their intensity.I haven't received pink dissipative bags with MOS parts from reputable distributors, but from "the street" I would say it is quite common. Heck, I have even seen foam disguised as dissipative with their pink colour but my EM voltmeter strongly disagrees.

author: Yansi
author_rank: Super Contributor
timestamp: November 21, 2019, 12:13:11 pm
content: Yes, it says it. Would be interesting to verify it. But how? Any ideas?I would not have problem with mosfets in the pink dissipative bags either - they also come in them from time to time.

author: Ampera
author_rank: Super Contributor
timestamp: November 21, 2019, 12:41:22 pm
content: As a person who has ordered many an old computer part off ebay, be thankful they didn't send it to you in tape and bubble wrap.I once got a Mach 64GX 2MB 2D card off ebay that was shipped in newspaper, which actually is at least fairly statically dead, but looked like it had been used as a hockey puckdidn't work, but the listing claimed it did, and I got my money back (and got to keep the card, which was fixed with a single bodge wire).

author: wraper
author_rank: Unknown
timestamp: November 21, 2019, 01:22:56 pm
content: Quote from: Yansi on November 21, 2019, 10:58:29 amDunno how actually antistatic that is but computer HDD, SSD, RAM, CPU usually come in similar packaging with no other ESD protection. IMHO if it's good enough for CPU which costs hundred to thousands of dollars, should be good enough for MOSFETS.

author: magic
author_rank: Super Contributor
timestamp: November 21, 2019, 03:23:42 pm
content: Quote from: CJay on November 21, 2019, 11:44:12 amIndeed, they went completely nuts with ESD and humidity paranoia a few years ago.I order a few stupid SMD LEDs and they pack them in a hermetically sealed antistatic bag with a desiccant and humidity detector inside

author: wraper
author_rank: Unknown
timestamp: November 21, 2019, 03:49:14 pm
content: Quote from: magic on November 21, 2019, 03:23:42 pmHigh efficiency LEDs are ESD sensitive. Also most of SMD LEDs are moisture sensitive. If you reflow them after storing them at free air, there is high chance of failures.

author: rsjsouza
author_rank: Super Contributor
timestamp: November 21, 2019, 04:40:41 pm
content: Exactly. Humidity can not only cause corrosion on the pads (which will hinder soldering) but it can fog LED lenses, stick to the epoxy enclosure and cause failures, especially during soldering. I recall hygroscopic packaging on late 1990s/early 2000s that caused failures in processors due to microfissures on the enclosure.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 21, 2019, 04:48:11 pm
content: Quote from: magic on November 21, 2019, 03:23:42 pmThe dessicant, as said above, is definitely not stupid. Reflowing such components that have not been stored this way would require baking before using them, which takes additional time and steps. Failing to do so can lead to catatrophic failures.Of course for someone mainly using the parts for hand-soldering (with a soldering iron), it's less likely to cause problems (but not 100% unlikely), but using hot air or reflow ovens, it definitely is.

author: magic
author_rank: Super Contributor
timestamp: November 21, 2019, 05:39:14 pm
content: I know the reasons, but I order quantities of 10 or so for one project as a consumer, then it becomes kinda silly.I would be buying from hobbyist oriented stores which don't bother with it, but their catalog just isn't the same.

author: wraper
author_rank: Unknown
timestamp: November 21, 2019, 06:59:24 pm
content: Quote from: magic on November 21, 2019, 05:39:14 pmApparently you wanna be a special snowflake who receives impropery packaged parts. Other customers on the other hand would be outraged if they receive parts in package you suggested. And it does not matter if there are 10 or 1000. Even if you assemble single prototype, parts may fail.

author: thm_w
author_rank: Super Contributor
timestamp: November 21, 2019, 09:51:16 pm
content: LCSC used to package passive parts loose or in plastic bags (resistors, capacitors, heatshrink, etc.) which I was fine with. Now they've switched to packingeverythingin conductive static bags. Wasted money but maybe its simpler.

author: rsjsouza
author_rank: Super Contributor
timestamp: November 22, 2019, 11:38:59 am
content: Quote from: thm_w on November 21, 2019, 09:51:16 pmThis is likely the probable explanation. The difference in cost is easily offset by a single customer return and the taint to the distributor's reputation/image. A mistake in packaging can easily be done, especially in small quantity distributors which require manual handling of the parts.

author: coppice
author_rank: Super Contributor
timestamp: November 22, 2019, 11:48:01 am
content: Quote from: Yansi on November 13, 2019, 08:28:45 pm99% of uses of TO220 require static dissipative packaging. There are a small number of passives in TO220 packages, so its not 100%. I've never seen TO220 packaging which is not static dissipative.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 23, 2019, 01:04:34 pm
content: Quote from: magic on November 21, 2019, 03:23:42 pmMany SMD LEDs (MSL 4) absolutely do need this sealed bag with desiccant. Else, expect around 100% failure rate. I have seen 50% failure rate after a bag was opened for just two weeks on my desk for second batch, while the first batch was perfect. Baking them is a stupidly long process.Some SMD LEDs are less sensitive, but it's less expensive to pack them all in a similar way.I don't understand why being a hobbyist or just ordering 10 has anything to do with this. If I order parts as a hobbyist, it's still important they work.

author: Siwastaja
author_rank: Super Contributor
timestamp: November 23, 2019, 01:10:43 pm
content: Quote from: coppice on November 22, 2019, 11:48:01 amMost plastic tubes I've seen indeed have "static dissipative", "antistatic" or similar printed to them. I think it's fair to assume most tubes are this way. Some low-quality distributors may have a source of non-static-dissipative component tubes, but Yansi's default assumption that the tubes are "not even dissipative" is definitely wrong. Naturally, no one is complaining because the packagingismost often done properly: static dissipative plastic tubes in an ESD shielding bag.