Transducer packaging
The application describes a package for a MEMS transducer. The package has a package substrate having an acoustic port formed in the package substrate. The acoustic port comprises a first acoustic port volume portion and a second acoustic port volume portion, the first acoustic port volume portion being separated from the second acoustic port volume potion by a discontinuity in a sidewall of the substrate. The cross sectional area of the first acoustic port volume portion is greater than the cross sectional area of the second acoustic port volume portion. A barrier may be attached to the upper surface of the package substrate so as to seal or cover the acoustic port.
1. A MEMS transducer package having a package substrate, wherein:
an acoustic port extends from a first opening in a first surface of the package substrate to a second opening in a second surface of the package substrate;
a flexible membrane overlies the acoustic port; and
a barrier is provided on or at the first surface at the first opening of the package substrate between the flexible membrane and the acoustic port; wherein the barrier moves in response to a pressure differential across the barrier, and the movement of the barrier causes a corresponding movement of the flexible membrane.
2. A package as claimed in claim 1 , wherein the barrier is supported in relation to the first surface of the package substrate so as to form a seal or cover over the acoustic port.
3. A package as claimed in claim 1 , wherein the first opening is defined by a recess formed in the first surface of the package, the recess forming a first acoustic volume portion.
4. A package as claimed in claim 1 , wherein the cross-sectional area of the opening in the first surface of the package substrate is greater than the cross sectional area of the opening in the second surface of the package substrate.
5. A package for a MEMS transducer as claimed in claim 1 , wherein the shape of one or both of the first and second opening may be one or more of circular, square and rectangular.
6. A package as claimed in claim 1 , wherein the substrate comprises a printed circuit board.
7. A package as claimed in claim 6 , wherein the printed circuit board comprises a multi-layer structure and wherein the first opening in the first surface of the package substrate is formed by a region of one or more upper layers of the printed circuit board where material has been removed.
8. A package as claimed in claim 1 , further comprising a MEMS transducer, wherein the MEMS transducer comprises a flexible membrane.
9. A package as claimed in claim 8 , wherein the MEMS transducer is provided within the package such that the flexible membrane overlies the acoustic port.
10. A package as claimed in claim 1 , wherein the barrier is provided between the flexible membrane and the first surface of the package substrate.
11. A package as claimed in claim 1 , wherein the barrier is formed from a substantially non-porous material.
12. A package as claimed in claim 1 , wherein the barrier comprises one or more of silicone or rubber.
13. A package as claimed in claim 1 , wherein the barrier is supported relative to the upper surface of the package substrate such that the barrier is able to flex in response to pressure variations.
14. A package as claimed in claim 1 , wherein the barrier is adhered to the first surface of the package substrate.
15. A package as claimed in claim 1 , wherein the barrier comprises at least one bleed hole for pressure equalisation.
16. A package as claimed in claim 1 , wherein the barrier substantially inhibits the flow of particles through the barrier.
17. A package as claimed in claim 1 , wherein the barrier is hydrophobic.
18. A package as claimed in claim 1 , wherein the barrier substantially closes the first opening.
19. A package as claimed in claim 1 , wherein the package further comprises a lid.