Dissertation/Thesis Abstract

The effects of the transition from tin-lead to lead -free solder on metal flow in the United States
by Dong, Jaimee Ilene, Ph.D., Yale University, 2008, 149; 3317262
Abstract (Summary)

Recent legislation and consumer pressure have caused a transition from tin-lead to lead-free solder in consumer electronics. This work compiles past sales and estimates future sales in the US for the following categories of electronics from the 1980's through 2025: cellular phones, computers, keyboards, hard copy peripherals, monitors, and televisions. US import/export and domestic production data for electronics were collected for 2002 to 2005. Based on country of origin, the proportion of leaded and lead-free products was estimated. Using estimated lifetimes and solder content of products, the amount of tin-lead and lead-free solder scrap in the US was calculated for the 1980's through 2025. The results show that lead will be almost completely phased out of electronic solder use in the US by 2012, and that tin use in electronic solder will increase because of the high tin content of lead-free solders.

Electronic scrap is sent to one of four destinations: export, landfill, secondary copper smelters, or incineration. Solder constituent metals (lead, tin, silver, and copper) are recovered for re-use in the US from copper smelters. Current recovery rates at copper smelters for copper and silver are above 95%, but there is no tin or lead recovery.

Three different scenarios were used to determine the destination of electronic scrap in 2025 in the US. The first is a "business as usual" scenario; the proportions of electronic scrap sent to the four destinations in 2025 were assumed equal to 2005. For the second, a federal recycling law requires the majority of electronic scrap be recycled at copper smelters. This scenario significantly increases silver and copper recovery, resulting in more silver and copper recovered than used for electronic solder production in the US. The third scenario is the same as the second, except that the recovery of tin and lead is assumed equal to current higher European recovery rates. Under this scenario, more tin, lead, silver, and copper are recovered than are used in electronic solder production in the US. The augmented tin recovery in the third scenario would mitigate the increased use of tin due to the transition to lead-free solder.

Indexing (document details)
Advisor: Graedel, Thomas E.
School: Yale University
School Location: United States -- Connecticut
Source: DAI-B 69/06, Dissertation Abstracts International
Subjects: Environmental engineering
Keywords: Electronic scrap, Lead-free solder, Metal flow, Tin-lead solder
Publication Number: 3317262
ISBN: 9780549653035
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