HMP solder tin whiskers? - Page 1
Forum section: electronics / projects

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 27, 2015, 08:26:46 pm
content: HMP solder has high tin content, will it grow whiskers? What if I solder a Sn/Pb "skin" over the HMP joint? Will that help prevent whiskers?

author: rdl
author_rank: Super Contributor
timestamp: June 27, 2015, 08:36:56 pm
content: Quote from: Alex Eisenhut on June 27, 2015, 08:26:46 pmAre you sure about the high Sn content? I thought it was mostly Pb. Of course, I'm wrong a lot.

author: Alphatronique
author_rank: Regular Contributor
timestamp: June 27, 2015, 08:46:42 pm
content: according to wiki HMP was Pb93.5 Sn5 Ag1.5 ,so no tin wisker for sure whit that lead containnot forgot to wash hand after handle it ,lead poisoning really suck ,still have health issue more that 15 year later that stop using lead solder

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 27, 2015, 11:21:51 pm
content: Quote from: Alphatronique on June 27, 2015, 08:46:42 pm??Most HMP solders for electronics have a high tin content. The high lead stuff seems to be used for plumbing?One would assume with RoHS lead would be a no-no? But then again, I also, am wrong a lot...OK, so generally speaking, can you stop tin whiskers from growing with a clever coating of Sn/Pb solder?

author: wraper
author_rank: Unknown
timestamp: June 27, 2015, 11:30:25 pm
content: Mixing different solders is very stupid idea. You will get some mixed crap alloy.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 27, 2015, 11:31:43 pm
content: Here, this is my reference point:http://www.newark.com/multicore-solder/1399075-m-2metre/solder-wire-99-7-0-3-sn-cu-227/dp/93K2260Sn 99.7%. Maybe it's not for electronics, maybe it's wrong. I dunno.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 27, 2015, 11:32:27 pm
content: Quote from: wraper on June 27, 2015, 11:30:25 pmSez who, and who cares? Solder is already an alloy with four different phases...

author: rdl
author_rank: Super Contributor
timestamp: June 27, 2015, 11:44:52 pm
content: I don't think that solder you linked to is "high melting point solder". Lead free solder does melt at higher temperatures than regular leaded, but lower than high melt point (which contains mostly Pb and melts at over 260 C).

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 27, 2015, 11:48:15 pm
content: Quote from: rdl on June 27, 2015, 11:44:52 pmI see. I don't know why that showed up in a search then.What do you think this stuff is:http://www.ebay.ca/itm/260856270976?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AITThis listing changed the description often enough I have zero confidence in what he's selling.So true electronics HMP solder is mostly lead with RA flux?

author: rdl
author_rank: Super Contributor
timestamp: June 28, 2015, 12:02:30 am
content: There is no telling what that guy is selling since there is no information provided other than a brand name and a temperature. Try googling "multicore ersin"

author: wraper
author_rank: Unknown
timestamp: June 28, 2015, 01:26:20 am
content: Quote from: Alex Eisenhut on June 27, 2015, 11:32:27 pmSo you do care about hypothetical tin whiskers but don't care about brittle joints...

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: June 28, 2015, 01:49:12 pm
content: Quote from: wraper on June 28, 2015, 01:26:20 amCorrect. Tin whiskers are "hypothetical"? Do tell. Please explain how a skin over the joint will cause embrittlement faster than tin whisker growth.Anyways, I might just add air gun pellets to my iron before soldering and see how that works...

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 28, 2015, 04:42:41 pm
content: I don't know about skinning over, but if you can get roughly 5% Pb into the joint it won't generate whiskers. If you really care about whiskers this means fully reflowing the joint and adding enough lead containing solder to get the 5% level. You will need to remove excess solder to avoid other problems, and avoid overheating the board and nearby parts. Embrittlement is a concern, but will not be a problem in many situations.The real question is, if you are doing something that needs to be highly reliable (hence the need to worry about tin whiskers), why are you trying to salvage something that was done wrong in the first place? Is it really worth the effort, and will the rework damage the reliability as much or more than the chance of tin whiskers? Is the purchasing system that got this solder into your shop up to the task of making sure the other pieces are reliable? Reliability requires consistent effort in many places.

author: marshallh
author_rank: Unknown
timestamp: June 28, 2015, 07:01:16 pm
content: Most high reliability applications use conformal coatings and underfills to prevent whiskers from posing a problem.

author: DanielS
author_rank: Frequent Contributor
timestamp: June 28, 2015, 09:52:39 pm
content: Quote from: Alex Eisenhut on June 27, 2015, 11:21:51 pmMost countries where health and environment actually matter have banned the use of lead in plumbing well over a decade ago.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 28, 2015, 11:29:32 pm
content: Quote from: marshallh on June 28, 2015, 07:01:16 pmTin whiskers have been demonstrated to grow through conformal coatings. Even the best ones. Conformal coatings do prevent direct contact from a whisker that has grown through a coating to another base conductor, but there is some chance that two whiskers will meet after penetrating the coating on their sources.