Fingerprint sensing device with heterogeneous coating structure comprising a mold
First Claim
1. A fingerprint sensing device comprising:
- a sensing chip comprising an array of sensing elements, said sensing elements being configured to be connected to readout circuitry for detecting a capacitive coupling between each of said sensing elements and a finger placed on a sensing surface of said sensing device;
a coating material arranged in a layer on top of said array of sensing elements, said coating material comprising a plurality of cavities filled with a mold material, wherein said mold material is deposited by compression molding;
wherein locations of said cavities correspond to locations of said sensing elements, such that a cross-section area of a cavity covers at least a portion of an area of a corresponding sensing element, said cavities comprising openings between adjacent cavities so that a liquid mold can flow between adjacent cavities during compression molding; and
wherein a dielectric constant of said mold material is higher than a dielectric constant of said coating material.
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Abstract
The invention relates to a fingerprint sensing device comprising a sensing chip comprising an array of capacitive sensing elements. The sensing device comprises a coating material arranged in a layer on top of the array of sensing elements, the coating material comprising a plurality of cavities filled with a mold material; wherein locations of the cavities correspond to locations of the sensing elements, such that a cross-section area of a cavity covers at least a portion of an area of a corresponding sensing element; and wherein a dielectric constant of the mold material is higher than a dielectric constant of the coating material. The invention also relates to a method for manufacturing such a device.
23 Citations
18 Claims
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1. A fingerprint sensing device comprising:
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a sensing chip comprising an array of sensing elements, said sensing elements being configured to be connected to readout circuitry for detecting a capacitive coupling between each of said sensing elements and a finger placed on a sensing surface of said sensing device; a coating material arranged in a layer on top of said array of sensing elements, said coating material comprising a plurality of cavities filled with a mold material, wherein said mold material is deposited by compression molding;
wherein locations of said cavities correspond to locations of said sensing elements, such that a cross-section area of a cavity covers at least a portion of an area of a corresponding sensing element, said cavities comprising openings between adjacent cavities so that a liquid mold can flow between adjacent cavities during compression molding; and
wherein a dielectric constant of said mold material is higher than a dielectric constant of said coating material. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for manufacturing a fingerprint sensing device, said method comprising:
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providing a sensing chip comprising an array of sensing elements, said sensing elements being configured to be connected to readout circuitry for detecting a capacitive coupling between each of said sensing elements and a finger placed on a sensing surface of said sensing device; depositing a layer of a coating material covering said array of conductive sensing elements; forming a plurality of cavities in said coating material, wherein locations of said cavities correspond to locations of said sensing elements such that a cross-section area of a cavity covers at least a portion of an area of a corresponding sensing element and wherein forming said cavities comprises forming openings between adjacent cavities so that a liquid mold can flow between adjacent cavities during compression molding; and filling said cavities with a mold material, wherein said step of filling said cavities with the mold material comprises compression molding and wherein a dielectric constant of said mold material is higher than a dielectric constant of said coating material. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification