MANUFACTURE OF PYROELECTRIC INFRARED SENSOR

PURPOSE:To obtain a small-sized and low-cost sensor by a construction wherein the upper and lateral sides of a pyroelectric body provided with electrodes on both surfaces and disposed on a printed circuit board and the printed circuit board itself are covered with a subliming agent, an infrared long-pass filter slightly larger than the pyroelectric body is positioned with insulating resin, and the entire device is covered and heated. CONSTITUTION:A printed circuit board 2 to which EFT4 is connected and fixed is connected and fixed on the tops of terminals 3 buried in a base 5, and a pyroelectric body 1 having electrodes on both surfaces is disposed on the board 2. Then, a subliming agent 8, such as paraffin or wax, which is a (semi-)solid at normal temperature and is dissolved by heating is applied to cover the upper and lateral sides of the pyroelectric body 1 and the board 2 therewith. Next, an infrared long-pass filter 10 slightly larger (an angle or a diameter of 3-4mm.) than the pyroelectric body 1 (a 2mm. square) is positioned with insulating resin 9, and the entire device is covered with resin and cured. When or after it is cured, the entire device is heated to the sublimation temperature of the subliming agent 8, whereby the subliming agent 8 is made to sublime outside to be removed through innumerable pores in the resin 9. According to this construction, a visual field angle is maintained sufficiently even with the small filter 10, and thus a low-cost and small-sized sensor is obtained.