SMTA International Conference Proceedings


DOES COPPER DISSOLUTION IMPACT THROUGH-HOLE SOLDER JOINT RELIABILITY?

Authors: Craig Hamilton, et al.
Company: Celestica and IBM Corporation
Date Published: 10/4/2009   Conference: SMTA International


Abstract: The process issues relating to high copper dissolution rates have been well documented within the industry. The copper dissolution rates of SAC305/405 plus many of the leading alternative lead-free wave alloys have been characterized and pin-through-hole rework process windows assessed. One remaining gap within the industry is the understanding of how copper dissolution or thinning of the through-hole barrel wall/knee locations impacts the thermal and mechanical reliability of a pin-through-hole joint. This paper provides a summary of previous work performed to study and characterize the copper dissolution rates of various Pb-free wave alloys, as well as attempts to assess the impact of high levels of copper dissolution on the thermal reliability of a 14 I/O PDIP connector. A total of five PDIP connectors were designed onto a test vehicle, each individually daisy chained using bottomside traces, for in-situ monitoring. A design of experiment was defined as an attempt to vary the level of plated copper remaining after simulating the rework of the five PDIP connectors. Each board was subjected to 0-100°C ATC for 6,000 cycles with in-situ monitoring to detect failures throughout testing using data loggers. The results from this work indicate reliability concerns when a severe degree of copper dissolution occurs and shows signs of reduced reliability due to thinning of the copper plating thickness at the knee location. In addition, mechanical and thermo-mechanical loading are key elements necessary to confirm the reliability of a pin-through-hole joint, this paper however, focuses on thermal fatigue reliability assessment. Lastly, this paper will highlight limitations of the copper plating measurement methodology used and suggests alternative non-destructive options to inspect for copper dissolution within manufacturing environments.

Key words: copper dissolution, reliability



Members download articles for free:

Not a member yet?

What else do you get when you join SMTA? Read about all of the benefits that go along with membership.

Notice: Sharing of articles is restricted to just your immediate work group. Downloaded papers should not be stored on an external network or shared on the internet.


Back


SMTA Headquarters
6600 City West Parkway, Suite 300
Eden Prairie, MN 55344 USA

Phone +1 952.920.7682
Fax +1 952.926.1819