A single-chip integrated barometric pressure sensor using bulk silicon micromachining will be presented in this paper. The sensor chip incorporates the complete signal evaluation and trimming of the temperature coefficients and manufacturing tolerances. Sensor chips are mounted onto 6″ × 4″ thick film substrates for batch processing during assembly and trimming. The separated, individual devices can be used for surface mounting (SMD) on a printed circuit board (PCB). Specifications for the sensor functions, as well as the assembly and packaging concept, will be discussed.
Assembly, trimming and packaging are the most expensive production steps in the manufacture of sensors. In order to reduce the costs for sensors, we are introducing a standardization of sensor assembly and trimming with batch processing capability: after dicing, the integrated sensor chip is attached to a 6″ × 4″ thick film ceramic substrate with standard die-attaching glue.
Approximately 100 sensors can be bandied at one time in batch, for example for the barometric pressure sensor with standard thickfilm substrate handling equipment. The sensors on the 6″ × 4″ substrate are characterized at high temperature as well as at room temperature. The sensors are then trimmed using thyristor zapping. The individual chips are then protected by plastic caps and then separated by breaking. The package is suitable for direct mounting (SMD) onto PCB s.
This concept offers the following advantages:
standard die attach and wirebonding
wirebonding, characterization and trimming in batch form
surface mounting (SMD)
hermetic sealing possible