by Lee Whiteman
Today lead is used in the electronic manufacturing process as a tin lead alloy solder to attach and electrically interconnect components such as IC (Integrated Circuit) chips and resistors to PWBs (Printed Wiring Boards). But that will change!

Electronics manufacturers are being required to convert their production lines from tin lead solders to lead free solders. In Europe, the Waste Electrical and Electronic Equipment (WEEE) Directive and the Restriction of Hazardous Substances (RoHS) legislation stipulates that lead will be prohibited from electronic hardware by July 1, 2006. In Asia, specifically Japan, the Ministry of International Trade and Industry (MITI) has stipulated that commercial hardware must be 75% Lead Free by January 1, 2006. In the United States, while there is no formal legislation banning the use of lead in electronics, the Environmental Protection Agency's (EPA) Toxic Release Inventory Status requires that electronic manufacturers report lead usage greater than 100 lbs annually. Therefore, it can be concluded that Lead Free Solders will be implemented into electronic hardware in the near term.

When lead is banned, the electronic manufacturing industry will have to switch to solder that contains only tin, and perhaps some small amount of silver, copper, bismuth, or antimony to improve mechanical properties of the solder. These lead free soldering alloys, such as tin-copper-silver, have much higher melting temperatures than the tin lead solder currently used. This higher melting temperature is the source of many manufacturing issues. Electronics manufacturers must take into account how these materials will interact when incorporated into the manufacturing process.

There are specific challenges to introducing lead free solders in a production environment. Lead free solders do not wet as well as tin lead. Aggressive solder fluxes and nitrogen are recommended to improve solder ability. Components and board materials are more sensitive to moisture due to lead free solder's higher processing temperatures. From an inspection perspective, because lead free solder joints have a grainy dull appearance, the IPC is revising their visual inspection requirements to compensate for lead free solder joint differences.

The process variables for performing rework and repair operations with lead free solders also needs identification and quantification. There are concerns about the quality and reliability of lead free solders, which undergo rework and repair, as well as the impact that the solders higher temperature has on the board, the components, and the assemblies.

ACI recognized that Lead Fee Soldering impacts electronics manufacturing from system development through transition to production and sustainment. Since 1999, ACI has been actively investigating Lead Free Soldering. In 2000, ACI hosted an industrial forum with the IPC on Lead Free Soldering. In 2002, as member of the Lead Free Components Focus Group, ACI was awarded Soldertec's 2002 Lead Free Soldering Award for "pioneering work on the investigation and development of lead free and lead free components in the United States". This team proved that it was feasible to meet high reliability requirements with Lead Free solders. These activities are consistent with MANTECH’s objectives; to identify manufacturing challenges early and to provide timely solutions.

In order to understand the requirements of Lead Free Manufacturing, ACI has developed a Lead Free Manufacturing course. The course's objective is to introduce the technical variables associated with implementing lead free solders in a production environment. The two-day course is hands-on and utilizes ACI's Demonstration Factory. For more information on the course call the EMPF registrar at 610-362-1320.