3D Electronic packaging and interconnection

Lead Division
Ceramics, Division 8

Other Divisions Participating
Polymer processing, Division 4
Assembly & Packaging, Division 6
Micro-sensors & actuators, Division 11

Summary
This project will demonstrate a new innovative 3D-packaging technology for assembly of an IMU (inertial measurement unit), including gyroscopes and accelerometers. The optimal inclination angle is 35° for an IMU based on four gyros. This symmetrical geometry is obtained when the four gyros are mounted on the sides of a four-sided pyramid. The challenge is to find a packaging solution that gives a firm joining without introducing any stress to the structure. Considering that movements in the sub-Angstrom region are measured in the detection mode of the gyro, even the smallest distortion of the sensor structure can give serious effects. One of the problems is matching of coefficients of thermal expansion (CTE) for the different materials used. Liquid Crystal Polymers (LCP) filled with aramid fillers and ceramics have a CTE close to silicon. The pyramid should not only be integrated with external electrical connections and internal interconnects at the pyramid surface, but also in fully 3D inside the pyramid.

This demonstrator represents an important packaging concept for microsystems as it demonstrates both mechanical and electrical integration. The ceramic pyramid will be manufactured by solid freeform fabrication with ink jet printing (Modelmaker) and layer manufacturing (FCubic). These methods enable one step manufacturing of complex three-dimensional shapes with internal via holes in any type of ceramic material. Internal metallisation is possible by filling with metal paste and thermal decomposition of metal salt solutions. Other manufacturing methods are injection moulding of both ceramics and polymers. Electrical interconnects on the surface are best accomplished by direct laser scribing methods.

Status of this cross-divisional project
The output of this cross-divisional project was a demonstrator, completed in October 2006, a photograph of which is shown, bottom right. A report is now available here.