Some of my new SMD electrolytics have ESD warning stickers? - Page 1
Forum section: electronics / beginners

author: NT0Z
author_rank: Regular Contributor
timestamp: January 29, 2023, 02:32:55 am
content: Hi, gang,Some new SMD electrolytics I just bought are packaged in anti-static bags and come with ESD warning labels. Some even indicate how long they can remain outside the sealed anti-static bag before they need to be discarded!Did I just do a Rip Van Winkle?In the first 50 years of building electronic stuff I have never seen anything like that on an electrolytic cap?Of course, I'm pretty new to SMD, so maybe that's a thing?Thanks,--Kirk, NT0Z

author: langwadt
author_rank: Super Contributor
timestamp: January 29, 2023, 02:37:28 am
content: probably just use the same bags with the same stickers for everything, better to do it and not need it than need it and not do it

author: SeanB
author_rank: Super Contributor
timestamp: January 29, 2023, 09:16:16 am
content: Yes just common packaging, and the open time parameter is there so they can ensure that the parts will still reflow properly, as the factory tinning will slowly degrade with moisture and oxygen if it is not protected by being soldered into the circuit. Keep the package sealed till needed, and put dessicant sachets into the bag when opened, nice freshly baked ones that are dry, and seal the bag hermetically with a bar sealer as well.External PVC bags work well, simply put the entire original one in it, 2 sachets of dessicant, and heat seal, easiest using one of those cheap kitchen vacuum sealer units.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 29, 2023, 09:58:37 am
content: Quote from: NT0Z on January 29, 2023, 02:32:55 amThis has nothing to do with ESD. It's moisture sensitivity level, and means after that much time, parts may have absorbed too much moisture from air and cannot be reflow soldered safely, because at sudden high temperature, tiny water droplets boil inside cracking the package. You can carefully handsolder, or you can bake the parts slowly at lower temperature, then reflow as usual. Nothing needs to be discarded.Though, I think they probably have wrong moisture sensitivity level printed by accident, or manufacturer is playing extra safe for some weird reason. Usually such MSL ratings are seen with semiconductors in certain types of packages. I would not stress about it, even if you plan to reflow solder them.

author: NT0Z
author_rank: Regular Contributor
timestamp: January 30, 2023, 09:59:31 am
content: Thanks for the update.I haven't ever "toaster oven reflowed" anything with big electrolytic caps, but almost all of my work is hand soldered.--Kirk, NT0Z

author: Siwastaja
author_rank: Super Contributor
timestamp: January 30, 2023, 10:31:24 am
content: You can handsolder as usual, no problem at all. Of course, handsoldering SMD electrolytics is sometimes a tad difficult because only a small part of the lead is exposed to touch with the iron tip. Getting heat in from such small area is challenging. Pre-heating the whole board, even to something like just 100degC, helps.

author: Berni
author_rank: Super Contributor
timestamp: January 30, 2023, 10:41:43 am
content: Yep packaging methods sometimes get mixed up at distributors.I seen even just resistors delivered in silver metalized antistatic bag, but then got an opamp in just a blue/pink bag.It becomes even more of a random toss when you order ESD diodes. Some will pack it up anti static because it is a semiconductor, but then some don't because well... it is a diode that is designed to protect from static, so one would expect it to survive static.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 30, 2023, 10:49:02 am
content: Yeah. And remember, that silvery bag called colloquially "ESD bag" has two distinct features:* it's static shielding bag; ESD won't zap through it* it's moisture shielding bag; when perfectly sealed, things inside are protected from moist outside airThe pink bags have neither of these features. They are static dissipative, they don't develop static charge if rubbed against each other, but a particularly nasty ESD event can still zap through the bag. And there is no protection against moisture, except for very short times.

author: Berni
author_rank: Super Contributor
timestamp: January 30, 2023, 12:12:59 pm
content: Yeah the moisture bags are different.Those tend to be even more heavily metalized because moisture can slowly diffuse trough most plastics, so the metalization serves as a moisture barrier. But since they are metalized they also serve as antistatic bags. Main difference being they are heatsealed with a bag of descant inside.For just prototype use i don't bother with moisture sensitivity. The air humidity here is pretty low, so i just leave those bags open and use the parts without any bake drying. The more active fluxes take care of oxidation on the pins just fine while actual failure for moisture are "popcorning" where you can visually see the chip blown apart.(Never seen it happen with my own eyes so far)For production we have a machine that can vacuum and seal these bags back up, since there it is worth the effort for entire reels.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 30, 2023, 03:31:32 pm
content: SMD LEDs are especially sensitive to moisture in my experience, many even have MSL4 rating (instead of the more usual MSL3). LEDs are the only components I have had issues with in careless prototyping when the package has been left open on the table outside of winter season.For production, always follow the manufacturer instructions to the letter because yield problems can become frustratingly expensive.