Packaging for MEMS transducers
The Application describes a substrate design for a MEMS transducer package. The substrate is defined by a conductive layer which forms the upper and lower surfaces of the substrate. The substrate is also provided with a conductive portion which is electrically isolated from the rest of the conductive layer. The conductive portion is supported between a first plane defined by the upper surface of the substrate and a second plane defined by the lower surface of the substrate by an electrically insulating moulding substance.
1. A MEMS transducer package comprising:
a substrate forming a package substrate of the MEMS transducer package, the substrate comprising:
a conductive layer which defines upper and lower surfaces of the substrate;
a conductive portion which is electrically isolated from the conductive layer, wherein the conductive portion is supported between a first plane defined by the upper surface of the substrate and a second plane defined by the lower surface of the substrate by an electrically insulating moulding substance;
an intermediate substrate provided on the first planar surface of the package substrate, the intermediate substrate comprising an aperture and being arranged relative to the package substrate so as to overly a hole which extends through the package substrate from the upper planar surface to the lower planar surface thereof;
a MEMS transducer provided on the upper surface of the intermediate substrate;
electronic circuitry provided on the upper surface of the intermediate substrate; and
a conductive lid structure, wherein the lid structure is mounted to the upper surface of the substrate to define an interior chamber.
2. A MEMS transducer package as claimed in claim 1 wherein the conductive layer defines a conductive frame of the substrate.
3. A MEMS transducer package as claimed in claim 2 , wherein the conductive frame extends around the entire perimeter of the substrate.
4. A MEMS transducer package as claimed in claim 1 , wherein the moulding substance extends between the outer perimeter of the conductive portion and an inner wall of an aperture formed through the conductive layer of the substrate.
5. A MEMS transducer package as claimed in claim 4 , wherein the moulding substance defines a connecting frame.
6. A MEMS transducer package as claimed in claim 1 , comprising a plurality of conductive portions, each being electrically isolated from the conductive layer of the substrate and from each other, and wherein each conductive portion is supported between the first plane and the second plane by an electrically insulating moulding substance.
7. A MEMS transducer package as claimed in claim 1 , further comprising a hole which extends through the substrate from the upper planar surface to the lower planar surface thereof.
8. A MEMS transducer package as claimed in claim 1 , wherein the lid structure comprises a cover portion which extends over the substrate and at least one side wall.
9. A MEMS transducer package as claimed in claim 8 , wherein the conductive layer defines a conductive frame of the substrate, and wherein a terminating portion of the side wall(s) is mounted to the conductive frame of substrate.
10. A MEMS transducer package as claimed in claim 1 , wherein the MEMS transducer comprises a MEMS microphone transducer and comprises a flexible membrane which deflects in response to a pressure differential across the membrane, and wherein the MEMS microphone transducer is provided such that the flexible membrane overlies the aperture of the intermediate substrate.
11. A MEMS transducer package as claimed in claim 1 , wherein in use the package substrate and the lid structure are at ground potential.
12. An electronic device comprising a MEMS transducer package as claimed in claim 1 .
13. An electronic device as claimed in claim 12 , wherein the device is at least one of: a portable device; a battery powered device; an audio device; a computing device; a communications device; a personal media player; a headphone; a mobile telephone; a games device; and a voice controlled device.