| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the reliability of temperature cycle of an optical transmission module, where a coaxial ceramic BGA solder ball IC is mounted. <P>SOLUTION: The fillet of an underfill is optimized so as to have catenarian profile as a whole by arranging a flow prevention frame 5 for an underfill 6 and optimizing the size, the Young's modulus of the underfill is set to 5 Gpa or lower, and thermal expansion coefficient is set to 20-35 ppm/°C. The entire circumference of the solder ball mounting surface is chamfered by 0.5 mm or larger, or round-chamfered by 0.2 mm or larger. <P>COPYRIGHT: (C)2007,JPO&INPIT |
