Skip to content

Happy Birthday RoHS!

Folks,

It was five years ago today that RoHS was launched, amid concerns that the world of electronics would collapse due to the many challenges of lead-free (Pb-free) soldering.Well, we have five years of field data with no “the sky is falling” lead-free reliability events. But, has it been just five years?

No. As I mentioned in a recent post, Motorola implemented lead-free soldering around 2001 to take advantage of lead-free solder’s poorer spreading. Hmmmm, so it has been ten years! Not too bad!

Well it is actually better than that.SnAg3.5 solder has been used for decades in both:

1. Step soldering: with a eutectic temperature of 221C, SnAg3.5 can be used as the step previous to soldering with Sn63 or similar Pb-Free solder.The principle is to solder first with the SnAg3.5 and then with a lower melting temperature solder.The second soldering step is performed at a lower temperature, therefore not disturbing the SnAg3.5 solder joint or bond.

2. Mid-Temp Pb-Free alloy: when a solder that melts somewhat above the melting point of a “standard” solder alloy is needed, and it must be Pb-free, SnAg3.5 is often the choice. The automotive industry has used SnAg3.5 in these applications for decades.

While I still agree that lead-free solders need some time and experience, especially in harsh environments, to establish acceptable reliability for mission critical applications, the experience with SnAg3.5 is adding to lead-free solder’s reliability portfolio.

This information came to light with the recent announcement by a major solder materials supplier that they would no longer supply SnAg3.5.But take heart, Indium Corporation still supplies SnAg3.5.

Cheers,

Dr. Ron