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Industry Experts voice differing opinions on Lead vs. Lead-free Electronics
December 31, 1969 |Estimated reading time: 3 minutes
Lead-free?Yes!
For several years now, the lead-free emphasis has changed and implementation is closer than we think. In the early '90s, the legislative consideration regarding a ban on lead use had the electronics industry avoiding a switch toward an alternative because of possible process problems and fear of higher production costs. Recent discussions have touted commercial advantages associated with environmentally friendly products and improved high-temperature behavior of lead-free alloys. Suppliers also have contributed by providing solutions to reliability and processing challenges. These discussions have caused the industry to actively implement and begin manufacturing lead-free products.
In the United States, Motorola Inc. has built the first mobile telephone with lead-free solder paste. This application has demonstrated lead-free compatibility in a high-volume manufacturing environment.
Many suppliers have proactively devised solutions to the potential reliability failures and process challenges that can arise in lead-free assemblies. Additionally, solder suppliers have identified the need for different flux chemistries, which provide similar properties as their leaded counterparts such as long stencil life, fine-pitch printability, etc.
Aside from solder manufacturers, the rest of the printed circuit board (PCB) assembly supply chain is investigating and researching known assembly failures. One of these failures is tin whiskers. The use of electrodeposited tin finish and tin-based lead-free solders poses a major reliability threat of producing tin whiskers. Research and investigation by Technic Advanced Technology Div. has identified the mechanism of tin whisker growth. The company demonstrated the important inter-relationship between grain size, grain structure, morphology, and preferred crystal orientation and the resultant effects on deposit stress and tin whisker formation. Additionally, they provided information on a new tin plating chemistry that has been formulated specifically to incorporate the elements of this discovery.
Although the lead-free process window has decreased tremendously and lead-free process optimization is in its infancy, many manufacturers have proven a lead-free process is possible. Suppliers also have provided materials that will work in a lead-free process, and data has proven that lead-free products are reliable.
Tippy Wicker,Director of Product Management, may be contacted at Qualitek International Inc., 315 Fairbank St., Addison, IL 60101; E-mail: twicker@qualitek.com.
Jumping Off the Lead-free Cliff
Do you remember when peer pressure influenced many of your decisions and your parents tried to be the voice of wisdom and logic in the face of the prevailing fads and trends? Those days are back! Only this time the pressure is that if you want to compete in a global marketplace, you have to get lead-free, and the voice of wisdom and logic is scientific facts. Here are just a few facts against going lead-free:
Fact #1: Electronics manufacturing accounts for only 0.6 percent of the annual lead consumption. The amount of lead used in electronics manufacturing and assembly in the United States has been shown to produce no significant environmental or health hazards.
Fact #2: Silver can contaminate and copper can diffuse to cause failure. The Environmental Protection Agency (EPA) classifies silver as a "heavy metal" pollutant. Silver contamination of just 0.05 mg/l may cause permanent blue-gray discoloration of the eyes and skin. Copper diffusion can deteriorate insulators, thereby causing shorts and leaky paths between conductors. Copper contamination has been linked to stomach and intestinal distress, liver and kidney damage, and anemia.
Fact #3: Lead-free processes require more expensive raw materials and process adjustments. Lead-free solder is significantly more costly, as are the lead-free components (at least the relatively few that are available). The hidden costs are in the process adjustments.
Most lead-free solders have higher melting temperatures, which can contribute to higher oxidation (dross) levels. Also, some no-clean and pure rosin fluxes may become inactive at those higher temperatures. To compensate for these process changes, you may need a nitrogen atmosphere, a solder recovery system, an efficient infrared (IR) preheater, a new flux and maybe even anaqueous cleaner.
As a wavesoldering equipment manufacturer, we essentially are neutral. Since we started making wavesoldering machines 30 years ago, our machines have been fully capable of handling any lead-free processes. Our customers are our main concern. The fact is that costly lead-free processes are not necessary to produce safe, reliable products. Unfortunately, it does appear that if you want to hang out with the "in crowd" in the global marketplace, you will need to cave into peer pressure and go lead-free.
Julie Fields, Media Coordinator, may be contacted at Technical Devices Co., 1707 Edgemoor Ln., Everett, WA 98203; (425) 348-0535; E-mail: julie@technicaldev.com.