super-strong Chinese leads! - Page 1
Forum section: electronics / general

author: djacobow
author_rank: Super Contributor
timestamp: April 28, 2019, 11:14:05 pm
content: So, I've got this little consumer toy that I've been selling and I wanted to get 2xAAA battery holders a bit cheaper. The holders I am using are either Keystone 2468 (https://www.digikey.com/product-detail/en/keystone-electronics/2468/36-2468-ND/303817) or one of a few equivalents.I decided to try my luck on AliExpress. Nobody seemed to be advertising this holder, but I contacted a few sellers of similar holders and one guy told me he could get them. He sent me some photos and a price and I crossed my fingers and ordered 600 units.So, anyway, they arrive in two boxes wrapped a kilometer of that distinctive China shipping tape, and the parts look fine. Clearly no-name knockoffs, but, hey, it's a battery holder. I start soldering these onto some boards and I notice about 1/4 have normal leads and about 3/4 have leads that are made from what seems to be the strongest metal on earth. I have a habit of putting my finger on a lead when I clip it, so that the scrap doesn't go flying, but with these leads, the lead is ejected with such force that it drew blood, every time -- ouch! I quickly switched to another approach, where I don goggles and clip away while pieces ricochet around the room. (hopefully not landing inside equipment) Furthermore, they're just completely destroying one pair of (cheap) dikes after another.I've never seen anything quite like it. I think the shortcut they took was to make the leads out of the same material that the springs are made from. No idea what it is.Oddly, the other bag of holders has the reverse ratio. Mostly normal leads, a few with super-power leads.Anyway, no real purpose in posting here. I'm able to use these, and it's not like I specified the lead material or anything, so I think I got decent value, but I'll probably go back to regular suppliers for the next batch. Ow!

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: April 29, 2019, 12:35:53 am
content: Quote from: djacobow on April 28, 2019, 11:14:05 pmIn my first industry job I was working as a tech building prototypes. I caused much consternation as I fired off leads in all directions in an open lab, with other techs around me.No one had eye protection on and there were open projects and expensive systems running open box under power all around. That's when my buddy who was physically huge and ready to punch me out pulled me aside and said watch what I do. He took his waste paper basket, the old all metal office style, put it between his knees and held the board he was clipping at a 45 degree angle in the open face of the basket. D'oh, Easy peasy.

author: wraper
author_rank: Unknown
timestamp: April 29, 2019, 12:55:51 am
content: Quote from: djacobow on April 28, 2019, 11:14:05 pmCheap side cutters are rated for cutting thin copper only. Good ones can cut spring steel without too much issue.

author: Housedad
author_rank: Frequent Contributor
timestamp: April 29, 2019, 01:01:04 am
content: A cheap towel over your hands captures everything

author: reboots
author_rank: Regular Contributor
timestamp: April 29, 2019, 01:24:40 am
content: Take a good, hard look at your solder joints for those battery holders. Perhaps flow some solder over the bare leads and observe how well it wets, whether it tends to ball, and so on. The Keystone leads are made from nickel-plated brass, which provides good solderability. It sounds as though the Chinese manufacturers took a shortcut and made their leads from steel, which may not have good solder compatibility. If you're relying on the leads to mechanically support the holder plus batteries, even superficially good-looking joints may crack and develop high resistance over time.

author: wraper
author_rank: Unknown
timestamp: April 29, 2019, 01:50:43 am
content: Quote from: reboots on April 29, 2019, 01:24:40 amSolders just fine if done properly. There are tons of components with steel terminals, say electrolytic capacitors.

author: djacobow
author_rank: Super Contributor
timestamp: April 29, 2019, 04:03:20 am
content: Thanks for these good ideas on how to handle the flying lead problem, guys. I'll definitely use one or more of these suggestions.I haven't noticed any solderability problems, other than not having enough thermal relief on the negative terminal in my first board revs. But I will go over them carefully to see how they hold up. The holder is held in place with VHB foam tape, but I was hoping the terminals would also help a bit.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 29, 2019, 04:04:44 am
content: Ironically, clean steel has better solderability than nickel. Tin plated (or gold, or..) is of course better not just for solderability but for corrosion resistance (shelf life) as well.As for the leads, who knows, entirely possible they grabbed whatever wire happened to be handy at the hardware store that day, and it happened to be music wire* rather than the usual sneaky copper-plated steel you find in cheap leads.And yeah, component leads are commonly steel, presumably/hopefully mild steel (probably half-hard condition?), copper then tin plated usually.*Which despite being plain carbon steel, thanks to repeated drawing, is actually incredibly strong, up there with superalloys (~250ksi tensile yield). Heh... at least, give or take how much rebar, chopped automobiles and floor sweepings they tossed in the melt that day...Tim

author: reboots
author_rank: Regular Contributor
timestamp: April 29, 2019, 09:36:39 pm
content: Quote from: T3sl4co1l on April 29, 2019, 04:04:44 amDon't lead us on like this, it's non-fair-ous.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 30, 2019, 12:19:35 am
content: Come on, don't be anarsole. Sit quietly and enjoy your ride:Tim