On July 1st, Toshiba Corporation's Semiconductor Company and Storage Products Company consolidated to form Semiconductor & Storage Products Company.This page describes reliability information of semiconductor products.

Analysis of a Surface-Mount Device Soldering Failure by Board Used

[As of April, 2011]

Purpose
A reflow soldering failure has occurred to a TSOP type I (the package with 42 alloy leads on the shorter side) on the CEM-3 board. The cause is determined.
Analysis and Result
Cross-sectionally cut and grinded contact of a lead and a board were observed with an optical microscope. A peel-off was found between the lead and the solder on the CEM-3 (Figure 1).
On the FR-4 board (Figure 2), on the contrary, no separation was found between the lead and the solder. The soldering failure is caused by the large thermal expansion and reduction of the CEM-3 board upon mounting. The CEM-3 has a larger coefficient of thermal expansion compared to FR-4 and has a much larger coefficient of thermal expansion compared to the leads. When heated and cooled through soldering, the difference between the expansion and reduction ratio of the board and the leads gaps the board and the leads.

This is [Figure 1 Cross-Section Observation Using CEM-3 Board].

Figure 1 Cross-Section Observation Using CEM-3 Board

This is [Figure 2 Cross-Section Observation Using FR-4 Board].

Figure 2 Cross-Section Observation Using FR-4 Board