A little background, RoHS is a European Union law. It stands for restriction of hazardous substances. This law restricts a handful of chemicals in electronics. Most notably, for those of us in electronic assembly – lead. The law essentially requires the elimination of lead from electronics solders. This law took effect on July 1, 2006. Surprisingly, this birthday has met with little fanfare considering the concerns it evoked when enacted. For almost 100 years, tin-lead solder was the standard for electronic assembly. The industry had decades-worth of reliability data on tin-lead solder and very little data on the lead-free solder replacements. So, there were concerns over how reliable the resulting lead-free solder electronics would be. In addition, there were concerns over how the European Union would inspect electronics to assure that the RoHS laws were met.
The enactment, on July 1, 2006, went surprisingly well. There were a few hiccups at the European Union borders with imported electronics from the U.S. and other countries, but I think, overall, it surprised people how smoothly it went. There have been a few issues and reliability concerns, but fewer than expected. There are still some concerns like tin whiskers, pad cratering, and some others, but overall there have been no "the sky is falling" type of reliability issues that some people expected. Some have pointed out that the much shorter lifespan of electronics in the RoHS era helps this situation. We just don't keep our smartphones that long.
One of the challenges in field reliability data is that electronic assemblers are reluctant to publish the data, as they consider the information proprietary. However, I have talked to a few managers responsible for such data, and they all confirm that the field reliability of lead-free assembled electronics is equal or better than that assembled with tin lead solder.
I did a nonscientific survey at the Dartmouth Engineering School in about 2011. I asked the information technology technicians that purchased electronics for Dartmouth's Engineering School if they have noticed a change in reliability since the industry went lead free. I should point out: They purchase millions of dollars of electronics a year. Their main response was, "What's lead free?" Their lack of knowledge of RoHS and the lead-free change in electronic is telling. They purchased thousands of pieces of electronics over five years and saw no difference in reliability as they never noticed a change.
Many preparations went into getting the world ready for RoHS. Some estimated worldwide $20 billion was spent, but I think that amount is low. As early as 2002, I was working with Indium Corporation by presenting workshops to customers to help them get ready for the July 1, 2006, RoHS day. We were supported in this effort by some partner companies in the electronics component, assembly equipment, and printed wiring board surface finish industries. Motorola graciously agreed to share their experience as an early adopter. I and others from Indium Corporation traveled the world giving these types of workshops. Though, even today there are still technical and reliability concerns, a critical issue is that the military is exempted from lead free, yet can't buy tin-lead compatible components. Lead-free reliability has not yet been established for the harsh conditions and 40-year lifespan of military electronics. However, companies like Indium Corporation continue to work alone, and with our customers, to address these and other electronic assembly challenges.