| 摘要 |
<p>A compact pressure sensor of capacitive type includes a pressure sensor house assembly (1), which contains a reference cavity in which a high vacuum exists and which has a minimum volume. The pressure sensor house comprises an upper base plate (3), a thinner shielding plate (6) and a movable diaphragm (5). A low, small cavity (13) is formed between the latter ones. A narrow channel (35) extends from the cavity (35) to the outside and forms together with it the reference cavity. At the mouth of the channel a recess (37) is provided, in which an elastically arranged getter body (41) which is capable of being thermally activated is placed, so that a portion of the surface of the getter body is a wall surface in the reference cavity. A closing lid (43) having a low projecting profile is arranged in a gastight way in the recess and is engaged with the getter body. When simultaneously closing the reference cavity and activating the getter body, the lid (43) is attached to a heating probe (65) at a distance from the sensor house (1) and the getter body is placed in the recess. The whole assembly is placed in a vacuum chamber (57) and the temperature is then increased to the temperature, at which the getter starts to be activated, and thereupon the probe is moved to a position in which the closing lid is in contact with the getter body but not tightly to the sensor house. The temperature of the probe is increased further for a final activation and in order to melt the joint material on the lid, heat then being conducted through the lid to the getter body, and thereupon the lid is attached to the house in a tight way and is fixed in this position. In this procedure simultaneously also various portions of the sensor house (1) can be heated to be attached to each other.</p> |
