MEMS mass flow sensor assembly and method of making the same
First Claim
1. A MEMS silicon thermal mass flow sensor assembly comprising:
- A MEMS silicon thermal mass flow sensor chip having four thermistors as sensing elements which include a micro-heater thermistor, an ambient temperature sensing thermistor, a upstream thermistor and a downstream thermistor;
wherein said MEMS silicon mass flow sensor chip having through-holes on silicon substrate that are filled with conductive materials and electrically connected to the thermistors on the front surface; and
A MEMS silicon mass flow sensor carrier having the printed circuitry board that provides direct soldering to the said silicon mass flow sensor; and
wherein the printed circuitry board can be equipped with or without control electronics;
wherein said MEMS silicon mass flow sensor chip having a thermal isolating cavity beneath the micro-heater thermistor, the upstream thermistor and the downstream thermistor;
wherein said MEMS silicon mass flow sensor chip having surface passivation with the highly thermal conductive materials;
wherein said MEMS silicon mass flow sensor chip having the backside contacts connecting to the conductive through substrate materials and is ready to connect through direct soldering to the sensor carrier; and
wherein in a case if the silicon substrate is conductive, the through substrate holes shall be in the form of through substrate rings that are filled with isolation materials.
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Abstract
A silicon mass flow sensor manufacture process that enables the backside contacts and eliminates the conventional front side wire binding process, and the assembly of such a mass flow sensor is disclosed in the present invention. The achieved assembly enhances the reliability by eliminating the binding wire exposure to the flow medium that may lead to detrimental failure due to the wire shortage or breakage while the miniature footprint could be maintained. The assembly further reduces flow instability from the flow sensor package including the bump of wire sealing. The invented mass flow sensor assembly can be a flow sensor module if the supporting sensor carrier is pre-designed with the control electronics. Without the control electronics, the said mass flow sensor assembly is easy to install into desired flow channels and connect to the external control electronics.
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Citations
14 Claims
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1. A MEMS silicon thermal mass flow sensor assembly comprising:
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A MEMS silicon thermal mass flow sensor chip having four thermistors as sensing elements which include a micro-heater thermistor, an ambient temperature sensing thermistor, a upstream thermistor and a downstream thermistor;
wherein said MEMS silicon mass flow sensor chip having through-holes on silicon substrate that are filled with conductive materials and electrically connected to the thermistors on the front surface; andA MEMS silicon mass flow sensor carrier having the printed circuitry board that provides direct soldering to the said silicon mass flow sensor; and
wherein the printed circuitry board can be equipped with or without control electronics;wherein said MEMS silicon mass flow sensor chip having a thermal isolating cavity beneath the micro-heater thermistor, the upstream thermistor and the downstream thermistor; wherein said MEMS silicon mass flow sensor chip having surface passivation with the highly thermal conductive materials; wherein said MEMS silicon mass flow sensor chip having the backside contacts connecting to the conductive through substrate materials and is ready to connect through direct soldering to the sensor carrier; and wherein in a case if the silicon substrate is conductive, the through substrate holes shall be in the form of through substrate rings that are filled with isolation materials. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification