Component Storage - Page 1
Forum section: electronics / beginners

author: Xenos
author_rank: Contributor
timestamp: February 18, 2022, 06:04:23 am
content: Hi,I recently jumped into the electronics hobby. I used to dabble 30ish years ago, but now I'm getting serious; as serious as you can get in hobby mode anyway. I am only doing breadboard and "through-hole" type projects at this time. I ordered a bunch of jellybeans and ICs from Digitek/Jameco/Mouser, with my selections based on reading posts here, and watching several videos posted by EEVBlog.My question revolves around the LM317Ts and LM337Ts I received from Mouser. These are the only parts I have received that are packed in sealed bags with a shelf life. Did I make a faux pas ordering these? Are there issues I should know about? I have not opened the bags.Thanks,Xenos

author: Berni
author_rank: Super Contributor
timestamp: February 18, 2022, 06:14:25 am
content: That is just a moisture protecting bag that is sealed with some silica gel desiccant inside.The molded case of chips can absorb moisture in high humidity environments. Once the chips go trough a reflow oven the moisture can turn to steam and crack the chip. This is mostly a concern for high volume manufacturing. For home use there is no need to worry about it as its very rare to happen.And if you do live in the middle of the amazon rainforest and your humidity is constantly hovering around 90% then you can still bake the chips at 120°C for an hour or so to drive out the moisture before putting them trough a reflow oven.So just cut open the bag and throw away the silica gel packet inside (Or keep it if you want, they can be revived by baking too) then just keep the bag open as with any other component. I tend to keep parts in original bags because they already have a sticker on them saying what is inside of it. However sometimes it is worth pulling off the label and replace the bag since sometimes parts come with ridiculously large bags.

author: Xenos
author_rank: Contributor
timestamp: February 18, 2022, 06:23:02 am
content: Thanks for the quick reply. I live in Northern (way north) California, and unfortunately for us, it has been oh so dry here. E.g., 16% humidity dry today. I'm debagging/rebagging and labeling all of my components for ease of access. As storage space is tight, I'd like to store these a little differently than the bags they shipped in.I appreciate the feedback,Xenos

author: Berni
author_rank: Super Contributor
timestamp: February 18, 2022, 06:40:23 am
content: 16% humidity is really dry, the chips are never going to absorb any kind of humidity at that rate. The humidity indicator paper inside is probably not even going to trip if you leave it in the open.(That paper chemically changes color when humid to indicate parts need baking before reflow soldering)This probably holds true for most areas of the world where you need to actually water your lawn for it to be green.

author: Xenos
author_rank: Contributor
timestamp: February 18, 2022, 06:45:52 am
content: After opening the pack I see why they sent them in SMD packaging. These do not appear to be TO-220-3 packages.

author: Berni
author_rank: Super Contributor
timestamp: February 18, 2022, 07:11:21 am
content: That is a bit of a weird package. It is TO-220 just with shorter pins bent for SMD soldering. Usually these are in D2PAK and similar packages. But looks like you can still bend the pins straight and use it like a TO-220. Best way to do that is grab some large pliers with a flat jaw and just squeeze down on the pin to flatten it in one shot, the pins quickly break if bent too many times.In general this moisture sensitive packaging is only used for SMD components since you don't tend to solder trough hole parts using a reflow oven. So when you see this kind of packing it most likely has SMD parts. Tho the component vendors sometimes get the packaging wrong too. I have received connectors in ESD safe bags before (How could ESD possibly damage a connector) while other times i have received ESD sensitive chips just throw into a regular clear plastic bag.Oh and on that topic dry environments do make static buildup a lot worse. So that would sooner be in danger of the chips rather than moisture. But not to worry no need to wear a static wrist band or something, i just make it a habit that when i sit down at a workbench i grab something grounded (Scope BNC, PSU earth, ESD mat etc...)

author: Xenos
author_rank: Contributor
timestamp: February 18, 2022, 07:31:56 am
content: The TI datasheet for the LM317 says this packaging is called TO-263 (see pg. 5 in the pdf linked below)http://www.ti.com/general/docs/suppproductinfo.tsp?distId=26&gotoUrl=http%3A%2F%2Fwww.ti.com%2Flit%2Fgpn%2Flm317-nI dont trust myself to bend the pins, so I'm going to call Mouser in the am to see about an exchange. Mouser has been great on my orders so far, so one booboo isn't a bother. It's not like I need the parts immediately. I'm still building my kit and workstation.RE grounding. My father was an INC back in the day. He taught Nuclear Engineering in the Navy up in Idaho during the 60s and then went on to instruments, training at Foxboro later on. One thing he drilled into me was to strap up whenever handling this stuff. Nothing worse than being in the middle of a project and blowing a part up because you didn't ground out, and then having to wait for replacements to arrive. It stuck with me through my computer building years of the 90s-2000s, and was one of my first purchases when I decided to start tinkering again.Thanks for your answers Berni. I really appreciate the help and guidance.Xenos

author: Berni
author_rank: Super Contributor
timestamp: February 18, 2022, 07:52:16 am
content: Chips used to be a lot more sensitive to static back in the 70s and 80s so it indeed is easy to blow one of those.These days all chips have built in ESD diodes on the pins so it is a lot more difficult to blow one, typically needing as least a strong enough static discharge for you to clearly feel the jolt. Same for modern computer parts.Never hurts to wear a strap tho. Some special high speed or RF chips are still really sensitive to static (they can't have built in ESD protection due to performance)

author: strawberry
author_rank: Super Contributor
timestamp: February 18, 2022, 12:44:00 pm
content: Quote from: Berni on February 18, 2022, 07:11:21 amNo. lead is too wide to be converted back to TH normally and by bending damage plating as wellonly ~1mm pin length is left