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Pressure transducer and mounting

  • US 4,542,435 A
  • Filed: 03/29/1984
  • Issued: 09/17/1985
  • Est. Priority Date: 03/29/1984
  • Status: Expired due to Term
First Claim
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1. A capacitive pressure measuring transducer comprising:

  • a diaphragm member formed of a single crystal of silicon by etching into both sides of said diaphragm recesses defining the deflecting region of said diaphragm;

    a pair of support plates of silicon anodically bonded to opposite sides of said diaphragm along the periphery of said defecting region and having pressure communicating passages extending therethrough;

    a thin layer of borosilicate glass interposed between said diaphragm and each of said support plates and extending over the entire surface of said support plates facing said diaphragm member to form pressure receiving cavities with said diaphragm recesses and to provide for electrical isolation and bonding between said diaphragm and said support plates, said layers being as thin as possible consistent with adequate bonding, acceptable stray capacitance and electrical isolation between said diaphragm and said plates; and

    a metallized region deposited on the surface of each of said glass layers opposite the deflecting region of said diaphragm to form on opposing sides of said diaphragm variable capacitors whose capacitances change in opposite sense with changes in the pressure being measured.

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