NASA report on tin whiskers in Toyota parts

NASA Report

CALCE Finds Toyota Tin Whiskers a 'Significant' Threat

Circuits Assembly: The teardown found tin whisker formations in in both vehicles. (It was not known if the tin whiskers was associated with any malfunctions during the life of either car.) "We were looking at the overall manufacturing of assembly circuit and looking for what level of construction had the potential for defects throughout the entire engine control system,” says Osterman, senior research scientist and the director of the CALCE Electronic Products and System Consortium.

CALCE’s analysis supported earlier findings by NASA of the presence of tin whiskers in the APPSs of multiple Camrys. But while the National Highway Traffic Safety Administration issued a report exonerating Toyota, CALCE found as many as six tin whiskers growing on one APPS, and concluded “the potential for a tin whisker shorting failure was 140/1 million. Considering the number of vehicles on the road, it is expected that this would present a significant safety hazard.”

Lack of Care in Reporting can Mislead Greatly Re Tin Whiskers

Dr. Lasky's Blog : "To be fair and thorough myself, I want to point out two things:

Several media, not just Circuitnet, picked up the original story regarding tin whiskers as a possible cause of Toyota’s problems. The original article appears here: http://www.techeye.net/chips/electronic-tin-whiskers-may-be-behind-toyota-recalls

2.Temporarily ignoring the poor science at the root of the “claim”, I maintain that editing out the key phrase “may be” from the original story contributes to an increased misunderstanding of the actual facts."

I know and respect the team at Circuitnet, but it seems like they made a pretty serious goof today. Their top story today had headlines stating: "Tin Whiskers Behind Toyota Recall." The link to this story takes us an article with the title "Electronic Tin Whiskers may be behind Toyota recalls."

So we start with a headline telling us that tin whiskers are behind the recall and when we go to the main article we see that tin whiskers may be behind the recalls. The person that the article is quoting is Keith Armstrong an EMI (electromagnetic interference) expert. In this article Armstrong states that EMI may be the culprit in Toyota brake malfunction.

From what I see in the article, Armstrong has no data, and has not looked at a failed Toyota brake system. He is just arguing that EMI may be the culprit. Who knows?

Armstrong is then quoted as saying that tin whiskers, in the lead-free solder, may be to blame for the recalls and he then references work by John Barnes. Barnes' exhaustive summary has nothing to say about tin whiskers in Toyota braking systems, just a bit about tin whiskers in general, in the over 1,000 pages about lead-free issues. Armstrong is then quoted as saying that the tin whisker problem, "has caused serious problems in the computer industry previously." The article at this link is dated 12 November 2002 and is simply a call for papers on tin whiskers at a conference. Strong suggestions for having no data!

I don't want to minimize the concern for tin whiskers, but the headline in Circuitnet and the article it links to have nothing factual to do with tin whiskers in the Toyota recall situation. Given the seriousness of this situation, this misleading reporting is troubling indeed.

Cheers,

Dr. Ron

PS: One commenter to the main article points out that Toyota uses leaded solder in the brake electronics. I don't know if this is true, but given the RoHS exemption that auto electronics has for lead, it would not surprise me.

Read more: http://blogs.indium.com/blog/an-interview-with-the-professor/0/0/lack-of-care-in-reporting-can-mislead-greatly-re-tin-whiskers#ixzz0j65EllRe

Are Solder-Related Tin Whiskers Implicated in Toyota Sudden Acceleration Issues?

INDIUM CORPORATION: "After my recent post on the fact that there was no data linking tin whiskers to the Toyota sudden acceleration issues, there continue to be more posts saying things like “Tin Whiskers Implicated in Unintended Acceleration Problems."

Many of these posts link back to the earlier TechEye post. The basis for all of the posts, is a paper written by EurIng Keith Armstrong"

Armstrong’s paper is titled: “Toyota ‘sticking pedals’ recall is a smokescreen, Their sudden unintended acceleration problem is caused by electronics either due to EMI, lead-free soldering or software ‘bugs.’” It does not appear that Armstrong’s paper was sponsored or refereed.

Since it appears that this entire wave of reporting implicating tin whiskers, in this important issue, emanates from Armstrong's paper, it is helpful to quote his entire comments on Tin Whiskers:

Read more: http://blogs.indium.com/blog/indium-corporation/0/0/are-solder-related-tin-whiskers-implicated-in-toyota-sudden-acceleration-issues#ixzz0j5ywpk3d

Note that, in this paper, there is no data or any evidence re: tin whiskers discussed from investigating any of the vehicles in question. All of this paper is an opinion. In addition, the title of Armstrong’s paper leaves no room for any other cause, it has to be electronics or software. This position is very strong indeed for having no supporting data.

More recently Bob Landman added these comments to the tin whisker discussion:

“the increased use of electronics in automobiles when mixed with RoHS can make for a deadly cocktail. We don’t know what the causative agent [in regard to the Toyota recalls] was, but I have heard recently of new autos showing up at dealers that will not start. That cause has been linked to tin whiskers.”

Bob heard this. There is no report and no data. Until Bob gives us a reference for some analysis and data, his comments are little more than hearsay. I searched the web in vain to find information related to Bob’s quote. In addition this comment is a little surprising, tin whiskers are usually associated with a certain amount of aging, hence not usually found in new products.

That tin whiskers exist and cause failures is irrefutable. NASA has an excellent website related to tin whiskers and failures caused by them. However, the total number of tin whisker fails reported is less than 100. Many other types of electronic failure modes would appear to be much more common.

My purpose of writing this post is not to suggest that tin whiskers are not a concern in lead-free electronics. However, it is a fundamental principle in engineering and science to only make pronouncements on how something failed, when they can be supported with data. No data supports implicating tin whiskers in the Toyota incidents. It is also troubling how readily many people referenced the work of Armstrong without apparently reading what he said and checking his sources and lack of data.

Read more: http://blogs.indium.com/blog/indium-corporation/0/0/are-solder-related-tin-whiskers-implicated-in-toyota-sudden-acceleration-issues#ixzz0j61dIWfd

Ron Lasky, Indium Corporation