PACKAGED DEVICE INCLUDING CAVITY PACKAGE WITH ELASTIC LAYER WITHIN MOLDING COMPOUND

• US 20160126443A1
• Filed: 10/31/2014
• Published: 05/05/2016
• Est. Priority Date: 10/31/2014
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Oppermann, Klaus-Guenter, Barfknecht, Andrew Thomas
• Granted Patent: US 9,680,445 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03H 9/0523 for flip-chip mounting
• CPC Class Codes: H03H 9/059 consisting of mounting pads or bumps
• CPC Class Codes: H03H 9/1014 the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the BAW device
• CPC Class Codes: H03H 9/1071 the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the SAW device
• CPC Class Codes: H05K 2201/10083 Electromechanical or electro-acoustic component, e.g. microphone
• CPC Class Codes: H05K 3/284 for encapsulating mounted components H05K1/185 takes precedence

Abstract

A device includes a substrate; a cavity package having a first surface attached to the substrate, the cavity package enclosing an electronic circuit; an elastic layer formed on a second surface of the cavity package, opposite the first surface; and a molding compound formed on the substrate, encasing the cavity package and the elastic layer. The elastic layer decouples stress between the cavity package and the molding compound encasing the cavity package, for maintaining structural integrity of the cavity package and for preventing separation of the cavity package from the substrate.

Claims

1. A device, comprising:

a substrate;

a hermetically sealed cavity package having a first surface attached to the substrate, the cavity package enclosing an electronic circuit;

an elastic layer formed on a second surface of the cavity package, opposite the first surface; and

a molding compound formed on the substrate, encasing the cavity package and the elastic layer,

wherein the elastic layer decouples stress between the cavity package and the molding compound encasing the cavity package, at least for maintaining structural integrity of the cavity package.

2. The device of claim 1, wherein the elastic layer comprises one of a polyimide material or a silicone elastomer material.

3. The device of claim 1, wherein the substrate comprises a laminate printed circuit board (PCB), and the first surface of the cavity package is attached to the laminate PCB via a plurality of solder joints.

4. The device of claim 1, wherein the cavity package comprises a base substrate, a lid and a seal-ring between the base substrate and the lid for bonding the base substrate and the lid.

5. The device of claim 4, wherein the electronic circuit is positioned in a cavity formed, at least in part, by an internal separation between the base substrate and the lid resulting from the seal-ring, and the seal-ring hermetically seals the electronic circuit positioned in the cavity.

6. The device of claim 5, wherein the cavity package further comprises a via formed through one of the lid and the base substrate, and a via seal surrounding a base of the via inside the cavity, the via seal further hermetically sealing the electronic circuit positioned in the cavity, and

wherein the via enables at least electrical connections between the electronic circuit and traces on the substrate.

7. The device of claim 6, wherein the electronic circuit comprises a plurality of resonators.

8. The device of claim 7, wherein the plurality of resonators comprise thin film bulk acoustic resonators (FBARs), solidly mounted resonators (SMRs), or surface acoustic wave (SAW) resonators.

9. The device of claim 6, wherein the via seal comprises a pedestal, which provides separation between the lid and the base wafer, and two metal layers on the pedestal, the two metal layers being joined to each other to provide the at least electrical connections.

10. A microcap die, comprising:

a base substrate;

a plurality of acoustic resonators attached to an inner surface of the base substrate;

a lid disposed over the base substrate;

a seal-ring disposed between the inner surface of the base substrate and an inner surface of the lid, and surrounding the plurality of acoustic resonators, the seal-ring forming a cavity between the inner surface of the lid and the inner surface of the base substrate containing the plurality of acoustic resonators, wherein the seal-ring provides a hermetic seal for the cavity;

an elastic layer formed on one of an outer surface of the lid or an outer surface of the base substrate; and

a molding compound formed over the base substrate, the seal-ring, the lid and the elastic layer,

wherein the elastic layer reduces stress between the molding compound and at least the seal-ring and the via seals for maintaining the hermetic seals.

11. The microcap die of claim 10, further comprising:

a conductive via formed through one of the base substrate and the lid to enable an electrical connection between the plurality of acoustic resonators outside the cavity; and

a via seal surrounding a base of the conductive via inside the cavity, the via seal providing a further hermetic seal for the cavity.

12. The microcap die of claim 10, wherein the one of the outer surface of the lid or the outer surface of the base substrate is electrically and mechanically attached to a printed circuit board (PCB) via a plurality of solder joints.

13. The microcap die of claim 10, wherein vertical surface traction force applied by the molding compound to the microcap die decreases as a thickness of the elastic layer increases.

14. The microcap die of claim 10, wherein the elastic layer is formed of a compliant material applied as a dry film.

15. The microcap die of claim 10, wherein the elastic layer is formed of a compliant material cast from a solution.

16. The microcap die of claim 10, wherein the elastic layer is formed of a compliant material applied by dispensing as a liquid.

17. A multi-chip module, comprising:

a printed circuit board (PCB);

a plurality of cavity packages attached to the PCB, each cavity package comprising;

a base substrate;

a lid;

a seal-ring bonding the base substrate and the lid, and forming a cavity between the base substrate and the lid for containing an electronic circuit; and

a via seal surrounding a base of a via passing through one of the base substrate and the lid to provide an electrical connection to the electronic circuit form outside the cavity, the seal-ring and the via seal hermetically sealing the cavity;

a plurality of elastic layers formed on the plurality of cavity packages, respectively; and

a molding compound formed on the PCB, encasing the plurality of cavity packages and the plurality of elastic layers formed on the plurality of cavity packages, wherein each elastic layer decouples stress between the corresponding cavity package and the molding compound.

18. The multi-chip module of claim 17, wherein each elastic layer comprises one of a polyimide material or a silicone elastomer material.

19. The multi-chip module of claim 18, wherein the one of an outer surface of the lid or an outer surface of the base substrate of each of the plurality of cavity packages is attached to the PCB via a corresponding plurality of solder joints.

20. The multi-chip module of claim 19, wherein each solder joint comprises a solder bump between contact pads formed on opposing surfaces of the lid and the PCB.