Evaluation of the Solderability of an Alternate Alloy

Abstract

This project is a part of General Purpose Lead Free assembly system, which has been planned to define a guideline compatible with tin-lead based soldering. Although tin-silver-copper solder pastes are in mainstream of lead-free, the composition of the pastes differs in areas. Europeans and North Americans would like to use Sn- (3.8-4.0) Ag- (0.6-0.7) Cu, whereas Japanese would like to use Sn-3.0Ag-0.5Cu. As HDP User Group had not had any experimental data about the Sn-3.0Ag-0.5Cu paste, the Japanese team decided to evaluate the solderability of this composition as an Alternate Solder Alloy. We hope that HDP User Group will be able to gather tremendous data and findings by sharing this activity with European / American activities on the Sn- (3.84.0) Ag- (0.6-0.7) Cu.

These will be sure to support updating the GPLF guideline. This Japanese team has done this activity with some non-members and advisors from component, material and manufacturing equipment suppliers, and other cooperative system integrators.

Objectives

Although there are lots of papers and reports on lead-free soldering joints, we rarely find the data showing minimum temperature, which assures good solder joints for practical printed wiring boards. As it is more difficult to find the data corroborating the consistency between the standards such as IPC/JEDEC and IEC and experimental results of printed wiring boards with big high pin-count packages and small BGAs/CSPs, we decided to evaluate for the following objectives.

Clarification of minimum temperature and time that assures good solder joints with Sn-3.0Ag-0.5Cu solder paste on both double-sided and single-sided boards

Clarification of recommending lower temperature profile within both JEDEC J-STD-020B and IEC 600682-58 CD, and lists of unsatisfied components beyond the standard profile.