Don't bother designing green anymore?

Hello, all.

I realize I am several days behind the main flow of this thread, but I had to pipe up about RoHS compliance. Enrico, you mention that you suppose every industry has gone over to RoHS, but there is one notable exception: aerospace and defense. I work for a defense contractor and we regularly exempt our products from the lead-free requirements of RoHS policies. This is because of the tin whiskers (which cause shorts) and poor shock and vibe performance of lead-free solders.

In fact, there are several new mil specs (military specifications) that explicitly prohibit tin-only solders or solder finishes. Also, there's the "Airworthiness Advisory AA-05-01, Lead-Free Solder" document (by the US Air Force) that concludes: “Though there are many alternative solder alloys available to replace traditional tin-lead, none of them has passed the reliability testing required of aerospace-quality hardware.”

So, although the commercial Airbus plane you're riding may be lead-free and green, rest assured that American missles and airforce planes will last longer and have higher reliability.

Seriously, though, I fear that the leap to lead-free solder is going to be paid back in catastrophic failures before we learn that a little lead is a small price to pay for critical systems such as transportation, medicine, and others.

Hello, all.

I realize I am several days behind the main flow of this thread, but I had to pipe up about RoHS compliance. Enrico, you mention that you suppose every industry has gone over to RoHS, but there is one notable exception: aerospace and defense. I work for a defense contractor and we regularly exempt our products from the lead-free requirements of RoHS policies. This is because of the tin whiskers (which cause shorts) and poor shock and vibe performance of lead-free solders.

In fact, there are several new mil specs (military specifications) that explicitly prohibit tin-only solders or solder finishes. Also, there's the "Airworthiness Advisory AA-05-01, Lead-Free Solder" document (by the US Air Force) that concludes: “Though there are many alternative solder alloys available to replace traditional tin-lead, none of them has passed the reliability testing required of aerospace-quality hardware.”

So, although the commercial Airbus plane you're riding may be lead-free and green, rest assured that American missles and airforce planes will last longer and have higher reliability.

Seriously, though, I fear that the leap to lead-free solder is going to be paid back in catastrophic failures before we learn that a little lead is a small price to pay for critical systems such as transportation, medicine, and others.

Hi juleigh,

I was aware of the 'special treatment' for the sectors you describe. Lead-free soldering is also not easy in a development stage. The transition from liquid to solid is too short. It results in bad solderjoints. I still use PbSn, but customers insist than even sample deliveries are lead-free. Sometimes this is checked.

I know about the tin-wiskers. Have you even head about zinc-wiskers? They cause also shorts and are found when cabinets are zinc plated (electro-plating). This is really nasty. The biggest problems occurs in computerrooms where the floors contain zinc plated frames. After opening the floor (for rerouting of cables) the computers are more likely to go defect because of air-born zinc parts sucked in by the blowers. The zinc needled are so small that the air filters can not prevent them from enthering the machine.

Best regards,

Enrico Migchels