Package structure of micro speaker and method for forming the same

Patent metadata

Field	Value
Publication number	US-12170877-B2
Application number	US-202218064426-A
Country	US
Kind code	B2
Filing date	Dec 12, 2022
Priority date	Dec 12, 2022
Publication date	Dec 17, 2024
Grant date	Dec 17, 2024

Abstract

A package structure of a micro speaker includes a substrate having a hollow chamber. A diaphragm is disposed on the top surface of the substrate. The diaphragm includes a first portion suspended over the hollow chamber and a second portion surrounding the first portion. In a plan view, the second portion of the diaphragm and the hollow chamber do not overlap. A coil is embedded in the first portion of the diaphragm. At least one dummy structure is embedded in the second portion of the diaphragm, and it is electrically isolated from the coil structure by the diaphragm. A carrier board is disposed on the bottom surface of the substrate. A permanent magnetic element is disposed on the carrier board and in the hollow chamber. A package lid is wrapped around the substrate and the diaphragm, and has a lid opening that exposes a portion of the diaphragm.

First claim

What is claimed is:

1. A package structure of a micro speaker, comprising:
a substrate having a hollow chamber;
a diaphragm disposed on a top surface of the substrate, wherein the diaphragm includes a first portion suspended over the hollow chamber and a second portion surrounding the first portion, wherein in a plan view, the second portion of the diaphragm and the hollow chamber do not overlap;
a coil structure embedded in the first portion of the diaphragm;
at least one dummy structure embedded in the second portion of the diaphragm, wherein the at least one dummy structure is electrically isolated from the coil structure by the diaphragm, wherein in a vertical direction that is perpendicular to the top surface of the substrate, a thickness of the at least one dummy structure is equal to a thickness of the coil structure; and
a carrier board disposed on a bottom surface of the substrate opposite the top surface.

2. The package structure of the micro speaker as claimed in claim 1 , wherein the diaphragm comprises polydimethylsiloxane (PDMS), phenolic epoxy resin, polyimide, or a combination thereof.

3. The package structure of the micro speaker as claimed in claim 1 , wherein the at least one dummy structure comprises a semiconductor material, a dielectric material, a metal material, or a combination thereof.

4. The package structure of the micro speaker as claimed in claim 1 , wherein the coil structure has a multi-layered structure, including a first metal layer, a second metal layer, and a dielectric layer interposed between the first metal layer and the second metal layer.

5. The package structure of the micro speaker as claimed in claim 4 , wherein the at least one dummy structure has the same multi-layered structure as the coil structure.

6. The package structure of the micro speaker as claimed in claim 5 , wherein in the vertical direction along which the first metal layer, the dielectric layer, and the second metal layer of the coil structure are stacked, the thickness of the at least one dummy structure is equal to the thickness of the coil structure.

7. The package structure of the micro speaker as claimed in claim 1 , wherein the at least one dummy structure comprises a plurality of dummy structures evenly distributed in the second portion of the diaphragm.

8. The package structure of the micro speaker as claimed in claim 7 , wherein each of the plurality of dummy structures has a square, rectangular, circular, hexagonal or curved shape.

9. The package structure of the micro speaker as claimed in claim 1 , wherein the at least one dummy structure comprises a single and continuous dummy structure having a shape corresponding to a shape of the second portion of the diaphragm.

10. The package structure of the micro speaker as claimed in claim 1 , wherein the coil structure comprises a first metal layer and a second metal layer, and
wherein the first metal layer has a spiral structure surrounding a central axis of the diaphragm, and the second metal layer crosses over the spiral structure of the first metal layer and is electrically connected to the first metal layer.

11. The package structure of the micro speaker as claimed in claim 1 , wherein the carrier board has at least one vent hole, and the at least one vent hole is configured to allow the hollow chamber to communicate with an external environment.

12. The package structure of the micro speaker as claimed in claim 1 , further comprising:
a package lid wrapped around the substrate and the diaphragm, wherein the package lid has a lid opening that exposes a portion of a top surface of the diaphragm.

13. The package structure of the micro speaker as claimed in claim 1 , further comprising:
a first permanent magnetic element disposed on the carrier board and in the hollow chamber; and
a second permanent magnetic element disposed on the package lid, wherein the second permanent magnetic element is located below or above the lid opening.

14. The package structure of the micro speaker as claimed in claim 1 , further comprising an etch stop layer disposed between the coil structure and the hollow chamber, wherein the etch stop layer overlaps the coil in the vertical direction that is perpendicular to the top surface of the substrate, and the etch stop layer is made of a metal material.

15. A method for forming a package structure of a micro speaker, comprising:
forming a coil structure on a top surface of a substrate, wherein forming the coil structure comprises:
forming a first metal layer on the top surface of the substrate;
forming a dielectric layer on the first metal layer; and
forming a second metal layer on the dielectric layer;

forming at least one dummy structure on the top surface of the substrate;
forming a diaphragm covering the coil structure and the at least one dummy structure, wherein the coil structure is embedded in a first portion of the diaphragm, and the at least one dummy structure is embedded in a second portion of the diaphragm surrounding the first portion, wherein the at least one dummy structure is electrically isolated from the coil structure by the diaphragm, wherein forming the at least one dummy structure comprises forming the at least one dummy structure having the same multi-layered structure as the coil structure;
forming a hollow chamber in the substrate, wherein in a plan view, the coil structure is aligned with the hollow chamber, and the at least one dummy structure and the hollow chamber do not overlap;
attaching a carrier board to a bottom surface of the substrate opposite the top surface.

16. The method as claimed in claim 15 , wherein the coil structure and the at least one dummy structure are formed by the same processes and the same materials.

17. The method as claimed in claim 15 , wherein the coil structure and the at least one dummy structure have the same thickness in a vertical direction perpendicular to the top surface of the substrate.

18. The method as claimed in claim 15 , wherein forming the at least one dummy structure comprises uniformly forming a plurality of discrete dummy structures in the second portion of the diaphragm.

19. The method as claimed in claim 15 , further comprising:
mounting a package lid on the carrier board, wherein the package lid is wrapped around the substrate and the diaphragm, and has a lid opening that exposes a portion of the diaphragm.

20. The method as claimed in claim 15 , wherein a first permanent magnetic element is mounted on the carrier board and positioned in the hollow chamber.

Assignees

• Fortemedia Inc

Inventors

• Xu Yu-Xuan
• Gong Shih-Chin

Classifications

• H04R1/025

  Arrangements for fixing loudspeaker transducers, e.g. in a box, furniture · CPC title

• H04R2307/025

  Diaphragms comprising polymeric materials · CPC title

• H04R7/18

  at the periphery · CPC title

• H04R31/006

  Interconnection of transducer parts (of diaphragm and outer suspension by moulding H04R31/003) · CPC title

• H04R31/003

  for diaphragms or their outer suspension · CPC title