Lead Free Assembly Guideline v3.0

This guideline contains a compilation of best-known design and manufacturing methods as well as material selection recommendations based on industry experience with Pb-free assembly to date. Those manufacturers of products with current legislation exemptions can use this information to assist them in developing their plans to convert product ranges so that they are fully Pb-free compliant. The guideline highlights best practice and outstanding technology concerns that will help producers to define product and process qualification strategies.

It took more than 50 years to develop the tin-lead (Sn/Pb) assembly system used in the electronics industry. During this period of time we continuously improved the process and built reliability into the process. In comparison, lead (Pb)-Free (Pb-free for the remainder of the document) assembly is still a relatively new technology for the electronics industry. Early Pb-free work started in the 1990’s. Development of mainstream Pb-free materials and processes began around 2000 in advance of environmental legislation introduced in 2006 which forced the elimination of Pb in many electronics products, including high volume consumer goods. Current legislative and market circumstances have driven the industry to make the transition to Pb-free in a relatively short time-frame. For producers of electronic systems that have very high reliability and long life expectations, the opportunities to fully characterize the risk of his transition have been limited as very little real time field performance data exists. While exemptions allowing continued use of Pb are currently in place for many of the products falling into this category, significant challenges still exist. In increasing numbers, component suppliers are announcing the termination of supply of their Pb containing products driven by market pressures from the consumer industry for environmentally compliant components. For producers of currently RoHS exempt products, this presents a major dilemma. Continuing to use leaded solder with its long history of reliability has compatibility issues with newly compliant components, particularly array packages with Pb-free solder balls. Alternatively transitioning their products to be full Pb-free assembly can be extremely costly due to extensive qualification requirements and may also be potentially risky in the long term. This document addresses many of the issues associated with transitioning high reliability and currently legislation exempt products.