Patent ID: 6651508
Filing Date: 2003-11-25
Classification: G01L

Abstract:
A pressure sensor comprising:a case; a semiconductor sensor chip having a front and a rear surface, the semiconductor sensor chip being mounted on the case by connecting the rear surface to the case and measuring a difference between a first pressure applied to the front surface and a second pressure applied to the rear surface; a first pressure introducing passage formed in the case, through which the first pressure is applied to the front surface; and a second pressure introducing passage formed in the case, through which the second pressure is applied to the rear surface, wherein: the front surface is covered with a first protecting member; a passage formed in the second pressure introducing passage and connected to the rear surface is filled with a second protecting member to prevent foreign particles from entering into the passage; the semiconductor sensor chip includes a cavity having an opening open to the rear surface and a diaphragm formed on the front surface at a bottom side of the cavity opposite to the opening; the rear surface of the sensor chip is attached to a substrate, which in turn is connected to the case, the substrate having a through-hole for introducing the second pressure, a cross-sectional area of the through-hole being smaller than that of the opening of the cavity; the through-hole is filled with the second protecting member; the passage formed in the second pressure introducing passage includes a pressure passage connected to the through-hole and a depressed portion connected to the pressure passage, the depressed portion having an opening larger than the pressure passage; both of the pressure passage and the depressed portion are filled with the second protecting member; and the opening of the depressed portion is more than two times larger than the pressure passage.