Mike S wrote: There are real concerns that lead-free solders are less reliable. Lead free solder joints are more fragile - http://www.pcbrc.com/dev/PDFs/WhitePaper-SACfragility1.pdf Little is known about how to avoid the "tin whisker" problem, and the corresponding reliability issues - http://ap.pennnet.com/Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID= 233627&VERSION_NUM=2&p=95
It's interesting to note that many life critical systems (medical, aerospace, military) are exempted from RoHS. ------------------------------------------------------------------- I hadn't seen that report on the fragility of lead-free solder joints. Thank you. It reinforces the point that ordinary solder containing lead has worked very well for nearly a century with an insignificant failure rate when joints are soldered properly. When we move into new technology we are breaking new ground no less than the day the Titanic sailed to New York. I was aware that the tin whisker problem is a real issue that has no immediate solution. However, from what I've read, the whisker problem is not an issue with the solder. It's an issue with using pure tin to coat the leads on some RoHS parts. The parts themselves are subject to growing deadly whiskers no matter what solder is used. A number of photos I've seen point out that the soldered part of the connection is free of whiskers while the pure tinned portions of the lead that were not subjected to solder grew the whiskers. The whiskers can grow weeks, months or even years after a part is installed and the whiskers can reach several mm in length, producing shorts between adjacent solder pads. Here's some pictures of the whiskers: http://nepp.nasa.gov/whisker/anecdote/20year/index.html The whiskers aren't getting the play in the press one might imagine because the consumer electronics industry isn't too concerned about them. They plan on your Ipod, computer, personal digital assistant, TV, cell phone or other personal electronics being discarded every year or two anyway, before the whiskers will render them useless. It's the military, space and other high-reliability applications who are concerned, and they aren't the ones to make the "front page" of the morning paper. I'm inclined to put my Elecraft rigs up there in reliability objectives with a satellite or missile. I don't plan to trash the rig in a year or two (my K2 is already going on 7 years old already!). Ron AC7AC _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
