Pressure sensor and method of fabrication thereof

A process for fabricating a pressure sensor comprising the steps of:

• disposing a pressure sensing element within a first chamber within a portion of a package of said sensor;
• disposing a signal processing element within a second chamber within said package portion;
• electrically interconnecting said two elements;
• leaving said second chamber and the signal processing element therein exposed to ambient pressure and exposed for adjustment while hermetically enclosing said first chamber and exposing said sensing element to a known test pressure;
• measuring electrical parameters of the signal processing element while applying the known test pressure to the pressure sensing element;
• laser trimming selected portions of the circuitry on the signal processing element consistent with the known test pressure to provide desired adjustments;
• removing the test pressure from the sensing element;
• and
• sealing an enclosing member to said package portion for hermetically sealing at least said first chamber from the ambient while providing a port which provides access to said first chamber.

A pressure sensor comprising:

• a package comprising a housing member having integral therewith an outside wall and an interior wall which define two chambers separated from each other by the interior wall;
• a pressure sensing element disposed in a first of said chambers, and a signal processing element disposed in a second of said chambers;
• a plurality of conductive leads extending through said interior wall and being exposed within each of said chambers;
• at least one of said leads having an enlarged portion that is in thermal contact with a substantial portion of the signal processing element;
• bonding wires electrically interconnecting said two elements to said conductive leads;
• a second wall in said housing member, spaced from said interior wall and extending up into said second chamber, and other walls in said second chamber defining a recess within said second chamber for receiving said signal processing element;
• inwardly sloped side walls on said recess that provide guide means for proper positioning of said signal processing element in said second chamber;
• a cover member on said housing member hermetically sealing said first chamber;
• a port in the cover member coupled to said first chamber for connection of said first chamber to a pressure to be sensed.

A process for fabricating a pressure sensor comprising the steps of:

• disposing a pressure sensing element within a first chamber within a portion of a package of said sensor;
• disposing a signal processing element within a second chamber within said package portion;
• electrically interconnecting said two elements;
• leaving said second chamber and the signal processing element therein unenclosed while hermetically enclosing said first chamber and exposing said sensing element to apparatus which generates a preselected test pressure;
• contacting the signal processing element for adjusting the electrical parameters thereof in accordance with the test pressure;
• removing the test pressure;
• and
• sealing an enclosing member to said package portion for hermetically sealing said two chambers from one another while providing a port which provides access to said first chamber.

A process for forming a pressure sensor assembly having first and second chambers with electrical leads communicating between chambers comprising the steps of:

• sealing bottom and side portions of the electrical leads so as to hermetically isolate the chambers from each other where the leads pass from one chamber to the other;
• attaching a back cover to a body portion of the pressure sensor assembly and forming a hermetic seal at the intersection of the back cover and the body portion;
• disposing a pressure sensor element within the first chamber and disposing a signal processing element in the second chamber;
• electrically coupling each of the elements to the electrical leads;
• coating a portion of the pressure sensor element and coating top and side portions of the portions of the electrical leads in the first chamber with a passivating material;
• hermetically enclosing the first chamber and exposing the sensing element to a preselected test pressure while leaving the second chamber and the processing element therein unenclosed;
• sensing signals from the processing element and adjusting portions of the processing element such that signals received therefrom correspond to the applied test pressure;
• removing the test pressure from the first chamber;
• coating a portion of the processing element and top and side portions of the portions of the electrical leads in the second chamber;
• and
• attaching a top cover to the body of the sensor for hermetically sealing the first chamber and thus hermetically isolating the first chamber from the second chamber, said top cover defining a port which provides access to the first chamber.

A pressure sensor comprising:

• a package comprising a housing member having integral therewith an outside wall and an interior wall which define two chambers separated from each other by the interior wall;
• a pressure sensing element disposed in a first of said chambers, and a signal processing element disposed in a second of said chambers;
• a plurality of conductive leads extending through said interior wall and being exposed within each of said chambers;
• at least one of said conductive leads having an enlarged portion that is in thermal contact with a substantial portion of the signal processing element;
• means for electrically interconnecting said two elements to said leads;
• a second wall in said housing, spaced from said interior wall and extending up from the bottom of said second chamber, for defining a recess within said second chamber for receipt of said signal processing element;
• inwardly sloped side walls on said recess that provide guide means for proper positioning of said signal processing element therein;
• a cover member on the housing hermetically sealing said first chamber;
• and
• a port on the cover member for coupling the first chamber to a pressure to be sensed.

A pressure sensor comprising:

• a package comprising a housing member having integral therewith an outside wall and an interior wall which define two chambers separated from each other by the interior wall;
• a pressure sensing element disposed in a first of said chambers,
• an integral bottom wall partially across a second of said chambers;
• a signal processing element supported by said bottom wall of said second chamber;
• a plurality of electrically conductive leads extending through said interior wall and being exposed within each of said chambers;
• bonding wires electrically interconnecting said two elements with said conductive leads;
• at least one of said leads having an enlarged portion that provides thermally conductive bottom wall portion for said second chamber;
• said signal processing element supported on said thermally conductive bottom wall portion in intimate thermal contact therewith;
• a closure member of a material having a higher thermal conductivity than that of material forming said housing, said closure member forming a bottom wall of said first chamber and extending beneath said interior wall to a position underlying said second chamber, effective to form a high thermal conductivity path for heat transfer from said first chamber to said processing element;
• a cover member on the housing hermetically sealing said first chamber;
• a port in said cover coupled to said first chamber for connection of said first chamber to a pressure to be sensed.

A pressure sensor comprising:

• a package comprising a housing member having integral therewith an outside wall and an interior wall which define two chambers separated from each other by the interior wall;
• a pressure sensing element disposed in a first of said chambers and a signal processing element disposed in a second of said chambers;
• a plurality of electrical conductive leads extending through said interior wall and being exposed within each of said chambers;
• at least one of said leads having an enlarged portion that provides a thermally conductive bottom wall portion for said second chamber;
• said signal processing element supported on said thermally conductive bottom wall portion in thermal contact therewith;
• means for electrically interconnecting said two elements to said conductive leads;
• a lip completely around said first chamber upper end that forms a cylinder which projects beyond the upper surface of adjacent portions of the housing member, effective to form an annular surface around said first chamber that can be selectively hermetically sealed;
• a cover member on the housing hermetically sealing said first chamber;
• a port in said cover coupled to said first chamber for connection of said first chamber to a pressure to be sensed.