BMI resins as low-stress alternatives to epoxies for semiconductor package assembly

Recent industry analyses indicate that higher-reliability, non-hermetic packages continue to be the trend in semiconductor packaging. Higher reliability means higher levels of JEDEC level performances (JEDEC L1) at higher reflow temperatures (260°C). Similar studies also indicate that companies are not willing to pay higher costs for the materials required to meet these harsher conditions, so improved-performance organic materials are still critical for these applications. Though it is becoming more obvious to manufacturers that adhesives exist to provide low-cost solutions to these issues, most package-level manufacturers only consider epoxy chemistries to be reliable enough to be used for their applications. High purity, low-stress X-bismaleimide (X-BMI) resins however, can offer significant advantages over rigid epoxies and have been used in production applications for over a decade. Though not widely understood, they are suitable for a range of die-attach, lid-sealing, underfilling and bonding applications for semiconductor package or heat-generating devices to provide stable thermal performance. These low-cost solutions are achieved while providing rapid, in-line processing. This paper will focus on the role of BMI resins as low-stress alternatives to rigid epoxies semiconductor package assembly.