New Perspective of Lead-Free
I read with interest the September Editor's Note on lead-free avionics (page 6) and the Safety column in the same issue (page 55) on tin whiskers. In the face of the oncoming lead-free solder requirements slated to take effect in 2006, I thought I would give you the perspective of a small avionics manufacturer. The requirement for avionics manufacturers is intended to help clean up our Earth. Although authorities have demonstrated no clear connection between dumped, lead-based-solder parts and dangerous lead levels, political logic tells us to join the bandwagon and help clean up the world.
We, as a small manufacturer, have reflected on the effects of this new requirement. Depending on the rule's interpretation, the effects on our industry may range from spending significant money and resources on duplicate inventories and redesigns of products to having to recertify our products. One extreme is benign; the other is radical. If the radical interpretation becomes true, many small companies will face harsh consequences, perhaps even closure, due mainly to recertification.
Follow me for a moment here. The new lead-free solder of choice reflows at 40 degrees C higher than the existing solder. This means that new printed circuit boards (PCBs), tolerant of higher heat and prepared for the new solder, will have to be used. In addition, new parts will need to be used, due to the same factors affecting the PCBs. If we are lucky, the new parts will be the same form factor as before. But if they are larger or of a different shape, the board will need to be re-laid out. This, potentially, could bring certification back into the picture due to potential changes in cross-talk, electro-magnetic interference, heat dissipation, power usage and other performance factors.
Authorities have, as yet, made no clear statement. However, having to recertify hundreds or thousands of parts will have a serious negative impact on the delivery of line replaceable units (LRUs) to our customers. Many smaller firms with a larger number of designs may perish.
Beyond the changes in parts, we must all recertify our processes under the new solder paradigm. Our company feels that although this may be a time-consuming exercise, it's not as threatening as the parts recertification problem. Running parallel production lines in the transition period also will be a problem, though probably a survivable one.
Another factor has to do with the unknown. For example, there are "whiskers"--little strands of solder material that grow out of the solder joint--that are highly conductive. So, in a high-density PCB, imagine the potential for shorts if the whisker problem is uncontrolled. The result may be Murphy's Law, where we might theoretically save the world from lead poisoning but imperil airplanes filled with passengers.
We will have to learn about lead-free solder, what good solder joints look like, and how to test and control the quality. There is not much time between now and the deadline in 2006, and I have observed few executives who yet grasp the possible implications of this mandate. And what's worse is that manufacturers should be making a coordinated effort to find a more logical and less costly implementation plan. I'm not yet aware of such an effort. It is not our intention to whine about the matter. But we hope that those setting the requirements are ready for the potential consequences, should the harshest of interpretations be promulgated. And we hope for a plan that will minimize delivery disruptions. To this end, we need a clear statement from authorities regarding recertification, and hopefully a streamlined certification process in the event that recertifications are required.
Taking a cue from the automotive industry regarding gas efficiency requirements, I suggest a compliance curve, where we could require 20 percent of a manufacturer's current output to be lead-free by 2006, 30 percent by 2007, 40 percent by 2008 and so on. This will allow us to implement lead-free designs while limiting disruptions. As older products die out, the compliance levels will only improve. This also will give us all time to study the unknown performance and stability issues such as whiskers in order to build safer products. We have been using lead for quite some time now, so a few more years under a rational transition plan makes the best sense.
Executive Vice President
In your Safety column titled "Terrorists on Camera" (August 2004, page 45), David Evans promotes an in-flight video security system. This system could be quickly and completely disabled with a 50-cent sheet of adhesive-backed labels and therefore gives a false sense of security.
Senior Mechanical Designer
L-3 Communications Avionics Systems
Grand Rapids, Mich.