This fall, the environmental initiatives affecting the electronics industry are on many minds. Are they on yours? The Restrictions on Hazardous Waste (RoHS) initiative and others in Europe, Japan, and California start in 2006. The initiatives ban lead (Pb), cadmium (Cd), and mercury (Hg), for starters, affecting solder, solder paste, coatings, plating, metal housings, and in some cases, cable. Recently, Connector Specifier and the National Electronics Manufacturing Initiative (NEMI) conducted a survey about connector technology for the 2005 NEMI Roadmap Study. Preliminary results show that more than 85% of those surveyed rank lead-free solderability as an important challenge for connectors in the next decade.
A Quick Vote on the Connector Specifier website showed that 44% of respondents plan to eliminate all lead from their products. Although 22% are "still evaluating the implications," the remaining respondents either specialize in lead-free processes or products, offer lead-free products, or plan to offer them in the future.
More than 1,200 people registered for an Oct. 5 Webcast, "Lead-Free Materials and Components," cohosted by sister publications Connector Specifier, Surface Mount Technology, and Advanced Packaging magazines. The question-and-answer session in the interactive forum was a veritable fountain of information. Michael Crisafulli, director of the Optoelectronics Strategic Business Unit at California Eastern Laboratories (CEL), shared his answers to the many questions he received after his presentation.
In response to a question about whether there are drawbacks to continuing to use a lead-based solder process with lead-free components, Crisafulli replied, "The primary drawback is that most Pb-free lead finishes/platings melt at much higher temperatures than current lead-based platings. This will cause wettability and bonding problems. Tin-bismuth (SnBi) plating is an exception to this general rule as long as the bismuth concentration is between 4% and 1% on the plating." "The issue is that not all parts are available as lead-free," said Crisafulli. "In many cases, components with lead cannot be soldered at the higher temperatures required by a lead-free process."
Crisafulli continued, "Some component manufacturers are simply switching to lead-free terminations and contract manufacturers have no choice but to use their lead-free parts along with other components that have lead-based terminations. Moreover, sometimes the solder reflows under the termination on discrete resisitors and capacitors, and does not wet to the termination itself. This phenomenon is attributable to parts over a year old, and termination oxidation on smaller components.
"A two-pass system is an alternative in some cases. This involves soldering the high-temp devices (Pb-free) first and then reflowing the low-temperature devices (Pb). This will only work for SMT devices and is highly dependent on the solder used."
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The next "Lead-Free" Webcast, "Equipment and Reflow," is scheduled for Jan. 18, 2005.
Valerie Coffey, Editor-in-Chief
valeriec@pennwell.com
