Managing MSL parts for hobbyists - Page 1
Forum section: electronics / projects

author: marcus
author_rank: Contributor
timestamp: September 18, 2018, 10:04:45 am
content: Hello,i had recently a talk with a colleague, i described how i manage MSL (moisture sensitive) parts at home.He was really amazed and this was something new to him, so i decided to post it here, maybe this is of interest for somebody.At work we have a nice machine for sealing ESD-Bags with a nitrogen purge function, but this is pretty pricey:https://www.plexpack.com/blog/products/mps-7103-vacuum-sealer-with-nitrogen-gas-flush/Since hobbyists use SMD components more and more they often have to deal with MSL classified parts.I use this bags i purchased from ebay (attention german ebay link) (no affiliation, only for example):https://www.ebay.de/itm/Rexoo-12tlg-Set-Vakuum-Beutel-60x40-cm-Aufbewahrungsbeutel-Tasche-T%C3%BCte-Vacuum/192313847702?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649You put your rolls or trays into this bag, throw a silica pack with it and vacuum it out with your home vacuum cleaner, and bahm! ready.Although it would be better to substitute the left air with nitrogen gas, the silica will absorb the left humidity and the vacuum bag protects for new contamination.Attached are some pics of my vacuumed parts:Have funMarcus

author: Mr. Scram
author_rank: Super Contributor
timestamp: September 18, 2018, 10:28:27 am
content: That's quite nice, but I'd be a bit concerned about ESD without any protection in that area.

author: marcus
author_rank: Contributor
timestamp: September 18, 2018, 10:40:51 am
content: Quote from: Mr. Scram on September 18, 2018, 10:28:27 amYes your quite right, i should pack the parts into ESD bags an then into the vacuum bag.For the trays i already did, but then laziness caught me

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 18, 2018, 06:05:24 pm
content: Well, it all depends on how long you intend to store them.For amateur work, I've found that storing those parts in their original bags with the dessicant and sealing them with tape is perfectly adequate. The bags usually come with paper humidity indicators that you can check every once in a while to make sure the bag's interior is still dry enough. Never had any problem with that.The biggest issue you can have with increased humidity is when using the components in reflow ovens anyway - a lot less when hand soldering them. Not many hobbyists use reflow ovens. (Yes I know some do! But do you?)

author: marcus
author_rank: Contributor
timestamp: September 18, 2018, 06:55:58 pm
content: Quote from: SiliconWizard on September 18, 2018, 06:05:24 pmI do a few boards per year in reflow oven, but i actually hadn't any issues neither.The problem i encountered a few times (over the last years) is some parts not taking solder very well. (I think the most of them were QFN which are known to be problematic)Especially parts i stored longer-ish.Overall i think this is about being a little paranoid, an i wanted to support people in their paranoia.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 18, 2018, 07:25:19 pm
content: With some sensitive parts you can have cracking in packages during reflow due to excess moisture vaporizing.You can always "bake" them before soldering them if you're unsure about their current moisture level (especially if they have been stored for a long time).

author: MT
author_rank: Super Contributor
timestamp: September 18, 2018, 08:26:28 pm
content: Dont trust the vacuum bags with screw lock they have a untight ziplock at the other end and can leak there, i have pillows etc in such and some opens after 5-6 months, others i had opens less then a week, it all depends on manufacturer and the spread is large. I would also recommend baking even if kept indoor dry.

author: Bassman59
author_rank: Super Contributor
timestamp: September 18, 2018, 10:19:20 pm
content: Quote from: SiliconWizard on September 18, 2018, 07:25:19 pmI wonder if that is an issue when using hot air to solder parts to a board.

author: coppercone2
author_rank: Super Contributor
timestamp: September 18, 2018, 10:53:28 pm
content: how quickly do parts absorb moisture? Like do they have a moisture-impedance thats source sensitive?Like if you get water on a part that was freshly unsealed sealed and wipe it off quickly, is the effect similar to diffusion of humidity over a long time period.. ? Do you need to immediately rebake it?I personally don't sweat it that much because I tend to solder these parts with an iron. I store them on little BLACKESDFOAM squares in organizer boxes, so my lab is not occupied by tons of freaking bags.I do think that a tiny parts oven would be a fun project though.

author: SiliconWizard
author_rank: Super Contributor
timestamp: September 18, 2018, 11:41:24 pm
content: Quote from: Bassman59 on September 18, 2018, 10:19:20 pmI guess so. That would probably depend on the type of component (whether it's a BGA, QFN/QFP with an exposed pad, etc) and how long you take to solder it. If it's a QFP and you're using hot air to save time, you're not going to heat it up completely so the risk is obviously much lower.