Printed circuit board and method of manufacturing the same

1. A printed circuit board comprising:

a first insulating layer;

a first wiring layer disposed on an upper surface of the first insulating layer;

a second insulating layer disposed above the first insulating layer, and on the first wiring layer;

a second wiring layer disposed on an upper surface of the second insulating layer;

a cavity disposed in the first insulating layer;

a piezoelectric substrate disposed in the cavity;

an electrode disposed on the piezoelectric substrate and configured to convert an electrical signal into an elastic wave or to convert an elastic wave into an electrical signal;

a first via extending through the second insulating layer and into the first insulating layer, and electrically connecting the electrode to the second wiring layer;

a second via extending through the second insulating layer and electrically connecting the first wiring layer to the second wiring layer; and

a sealing part disposed on the piezoelectric substrate, the sealing part enclosing the electrode and forming an air gap around the electrode.

2. The printed circuit board of claim 1 , wherein the sealing part comprises a non-conductive material.

3. The printed circuit board of claim 1 , wherein the air gap is filled with an electrode corrosion inhibitor.

4. The printed circuit board of claim 1 , wherein the electrode includes an interdigital transducer (IDT).

5. The printed circuit board of claim 1 , wherein the first insulating layer is a core layer.

6. A printed circuit board comprising:

a core layer comprising a cavity;

an elastic wave element disposed in the cavity, and comprising:

a piezoelectric substrate;

an IDT disposed on the piezoelectric substrate, and

a sealing part disposed on the piezoelectric substrate, the sealing part enclosing the IDT and forming an air gap around the IDT;

a first wiring layer disposed on an upper surface of the core layer;

an insulating layer disposed above the core layer and on the first wiring layer;

a second wiring layer disposed on an upper surface of the second insulating layer;

a first via extending through the insulating layer and into the core layer, and electrically connecting the IDT to the second wiring layer; and

a second via penetrating through the insulating layer and electrically connecting the first wiring layer to the second wiring layer.

7. The printed circuit board of claim 6 , wherein the sealing part comprises a non-conductive material.

8. The printed circuit board of claim 6 , wherein the air gap is filled with an electrode corrosion inhibitor.

9. A method of manufacturing a printed circuit board, the method comprising:

forming a cavity in a core layer;

forming a piezoelectric substrate in the cavity;

forming an electrode on the piezoelectric substrate, the electrode being configured to convert an electrical signal into an elastic wave or an elastic wave into an electrical signal;

forming a sealing part on the piezoelectric substrate to enclose the electrode and form an air gap around the electrode;

forming a first wiring layer on an upper surface of the core layer;

forming an insulating layer above the core layer and on the first wiring layer;

forming a second wiring layer on an upper surface of the insulating layer;

forming a first via in the insulating layer and the core layer, the first via electrically connecting the electrode to the second wiring layer; and

forming a second via in the insulating layer, the second via electrically connecting the first wiring layer to the second wiring layer.

10. The method of claim 9 , wherein the electrode comprises an IDT.

11. The method of claim 9 , wherein the sealing part comprises a non-conductive material.

12. The method of claim 9 , further comprising adjusting a thickness of the piezoelectric substrate or a thickness of the sealing part to control a size of the air gap.

13. The method of claim 9 , further comprising filling the air gap with an electrode corrosion inhibitor.

14. The method of claim 9 , wherein the forming of the piezoelectric substrate comprises injecting a piezoelectric material into the cavity and hardening the piezoelectric material.

15. The method of claim 9 , wherein the forming of the cavity comprises forming the cavity using a laser beam, a punch, or a blade.

16. A method of manufacturing a printed circuit board, the method comprising:

forming a cavity in a core layer;

forming a piezoelectric substrate in the cavity by injecting a piezoelectric material into the cavity and hardening the piezoelectric material;

forming an electrode on the piezoelectric substrate, the electrode being configured to convert an electrical signal into an elastic wave or an elastic wave into an electrical signal;

forming a sealing part on the piezoelectric substrate to enclose the electrode and form an air gap around the electrode;

forming insulating layers above and below the core layer; and

forming wiring layers on the insulating layers.

17. A method of manufacturing a printed circuit board, the method comprising:

forming a cavity in a core layer using a laser beam, a punch, or a blade;

forming a piezoelectric substrate in the cavity;

forming an electrode on the piezoelectric substrate, the electrode being configured to convert an electrical signal into an elastic wave or an elastic wave into an electrical signal;

forming a sealing part on the piezoelectric substrate to enclose the electrode and form an air gap around the electrode;

forming insulating layers above and below the core layer; and

forming wiring layers on the insulating layers.