The latest generation of wafer-level package technologies developed by National Semiconductor Corp., Santa Clara CA, uses a structure that enables high-reliability products with counts of 42 to 100 bumps at a 0.5mm pitch without any underfill.

According to National, higher bump-count packages enable designers to create more complex products with advanced features and pack them into a smaller space.

The micro SMDxt (micro Surface Mount Device extended technology) chip package provides superior electrical noise performance compared to standard wire-bonded devices, making it well-suited for high-performance mobile applications.

Thermal performance is comparable to other thermally enhanced packages such as QFN or leadless lead frame (LLP) with similar pin count. Reliability standards such as thermal cycling, thermal shock, and drop test, and flex test can be met without the use of an underfill, National says.

"The new micro SMDxt package offers the industry’s smallest footprint and improved performance while using standard surface mount assembly and rework processes," Sadanand Patil, National vice president, Package Technology Group, says.

First product that uses the new package is the LM4934 Boomer stereo audio subsystem in 42-bump micro SMDxt. Also new is the LM4935 complete Boomer audio subsystem with a mono Class D speaker driver packaged in a 49-bump micro SMDxt. It requires 70 percent less board space than existing devices.