Importance

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Abstract

A fluid pressure transducer assembly (10) includes an exemplary silicon or ceramic capacitive transducer (22) having a relatively flexible diaphragm portion (22e) mounted on a ceramic substrate or circuit board (18) over a bore (18a) so that the diaphragm is exposed to fluid pressure from a port (12m) received through the bore. The circuit board is received in a plastic housing (12) laterally positioned by guides (12e, 12f) on three height control pins (12d) to vertically position the circuit board a defined, precise distance above a platform (12b) on which a bead of adhesive sealing material has previously been placed, the sealing material having a height greater than the distance between a plane in which the free end of the height control pins lie and a plane in which the top surface of the platform lies. As a result, the circuit board is sealed to the plastic housing through a bead having a uniform, precise height all around its circumference to isolate temperature expansion stresses. According to another feature of the invention an electrically conductive layer (30a) is formed on the top surface of the circuit board beneath the transducer (22) and another electrically conductive layer (30b) is formed on the top surface of the transducer (22) electrically joined together to form an EMI shield.

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First Claim