Low-cost epoxy packaging of CMOS hall-effect compasses

For the first time, a compass using CMOS Hall-sensors in a low-cost epoxy package is presented. Due to the high mechanical stress sensitivity of CMOS Hall-sensors, such low-cost plastic or epoxy mold packages have not been a viable option for low-offset applications like the compass application. Instead, expensive ceramic packages have been used. A recently developed, stress insensitive, CMOS Hall-sensor, shows only a 1.65 mu T offset shift after epoxy molding, while maintaining its low 3 mu T (3 sigma) offset spread. After repeated thermal shock, the Hall sensor's offset returns almost completely to its original value. For the compass application, the two horizontal plane components of the earth's magnetic field have to be measured. So a package with two orthogonally aligned Hall-sensors was developed.