System and method for a coreless transformer

• US 9,041,505 B2
• Filed: 09/11/2013
• Issued: 05/26/2015
• Est. Priority Date: 09/07/2012
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Beer, Gottfried, Elrod, Urs, Brunner, Christiane, Kilger, Thomas
• Primary Examiner(s): Lian, Mangtin
• Application Number:
  US14/024,395
• Publication Number:
  US 20140070913A1
• Time in Patent Office: 622 Days
• Field of Search: 336/200, 336/182, 336/192, 336/232, 296/021, 296/05
• US Class Current: 336/192
• CPC Class Codes: H01F 2027/2819 Planar transformers with printed windings, e.g. surrounded by two cores and to be mounted on printed circuit
• CPC Class Codes: H01F 27/2804 Printed windings
• CPC Class Codes: H01F 41/041 Printed circuit coils apparatus or processes for manufacturing printed circuits in general H05K3/00
• CPC Class Codes: H01L 2224/12105 Bump connectors formed on an encapsulation of the semiconductor or solid-state body, e.g. bumps on chip-scale packages
• CPC Class Codes: H01L 23/49816 Spherical bumps on the substrate for external connection, e.g. ball grid arrays [BGA]
• CPC Class Codes: H01L 23/49822 Multilayer substrates multilayer metallisation on monolayer substrate H01L23/498
• CPC Class Codes: H01L 23/645 Inductive arrangements H01L23/647, H01L23/66 take precedence
• CPC Class Codes: H01L 24/19 Manufacturing methods of high density interconnect preforms
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor
• CPC Class Codes: Y10T 29/49071 by winding or coiling

Abstract

In accordance with an embodiment, a transformer includes a first coil disposed in a first conductive layer on a first side of a first dielectric layer, and a second coil disposed in a second conductive layer on a second side of the first dielectric layer. Each coil has a first end disposed inside its respective coil and a second end disposed at an outer perimeter of its respective coil. A first crossover disposed in the second conductive layer is directly connected to the first end of the first coil and extends past the outer perimeter of the first coil. In addition, a second crossover disposed in the first conductive layer is directly connected to the first end of the second coil and extends past the outer perimeter of the second coil.

Claims

1. A transformer comprising:

a first coil disposed in a first conductive layer in a first plane, the first coil comprising a first end disposed inside the first coil;

a second coil disposed in a second conductive layer in a second plane substantially parallel to the first plane a first distance in a vertical direction from the first coil, the second coil comprising a first end disposed inside the second coil;

a first crossover disposed in the second conductive layer, the first crossover directly connected to the first end of the first coil and extending past an outer perimeter of the first coil; and

a second crossover disposed in the first conductive layer, the second crossover directly connected to the first end of the second coil and extending past an outer perimeter of the second coil.

2. The transformer of claim 1, wherein a center of the first coil is laterally offset from a center of the second coil.

3. The transformer of claim 2, wherein a majority of a surface area of the first coil is not disposed directly opposite from a majority of a surface area of the second coil in the vertical direction.

4. The transformer according to claim 1, wherein:

the first end of the second coil is disposed outside the outer perimeter of the first coil; and

the first end of the second coil is disposed outside the outer perimeter of the second coil.

5. The transformer according to claim 1, wherein:

a first lateral distance between the first crossover and a nearest portion of the second coil is not less than a first critical distance; and

a second lateral distance between the second crossover and a nearest portion of the first coil is not less than a second critical distance.

6. The transformer according to claim 1, wherein the first coil and the second coil each comprise at least two turns.

7. The transformer of claim 1, further comprising a first dielectric layer disposed between the first coil and the second coil.

8. The transformer according to claim 7, wherein the first conductive layer, the first dielectric layer and the second conductive layer comprise layers in an embedded package.

9. The transformer of claim 7, wherein the first dielectric layer comprises a polymer material.

10. The transformer according to claim 1, wherein the first conductive layer and the second conductive layer are disposed on an integrated circuit.

24. The transformer of claim 7, wherein:

the transformer is coupled to a transceiver disposed on a same integrated circuit as the transformer; and

a majority of a surface area of the first coil in the first conductive layer on a first side of the first dielectric layer is disposed directly opposite from a majority of a surface area of the second coil disposed on a second side of the first dielectric layer.

25. The transformer of claim 7, wherein:

the transformer is coupled to a transceiver that is disposed on a same integrated circuit as the transformer; and

the first coil is laterally offset from the second coil, and

a majority of a surface area of the first coil in the first conductive layer on a first side of the first dielectric layer is not disposed directly opposite from a majority of a surface area of the second coil disposed on a second side of the first dielectric layer.

26. The transformer of claim 7, wherein:

the transformer is coupled to a transceiver that is disposed on an integrated circuit that separate from the transformer; and

a majority of a surface area of the first coil in the first conductive layer on a first side of the first dielectric layer is disposed directly opposite from a majority of a surface area of the second coil disposed on a second side of the first dielectric layer.

27. The transformer of claim 7, wherein:

the transformer is coupled to a transceiver that is disposed on an integrated circuit that separate from the transformer; and

the first coil is laterally offset from the second coil, and

a majority of a surface area of the first coil in the first conductive layer on a first side of the first dielectric layer is not disposed directly opposite from a majority of a surface area of the second coil disposed on a second side of the first dielectric layer.

11. An embedded package comprising:

a first coil disposed in a first conductive layer in a first plane, the first coil comprising a first end disposed inside the first coil;

a second coil disposed in a second conductive layer in a second plane substantially parallel to the first plane a first distance in a vertical direction from the first coil, the second coil comprising a first end disposed inside the second coil;

a first crossover disposed in the second conductive layer, the first crossover directly connected to the first end of the first coil and extending past an outer perimeter of the first coil; and

a second crossover disposed in the first conductive layer, the second crossover directly connected to the first end of the second coil and extending past an outer perimeter of the second coil.

12. The embedded package of claim 11, further comprising a first dielectric layer disposed between the first coil and the second coil.

13. The embedded package according to claim 12, further comprising at least one integrated circuit disposed over the first conductive layer, wherein the first dielectric layer comprises an encapsulating material disposed over the at least one integrated circuit.

14. The embedded package of claim 11, wherein a center of the first coil is laterally offset from a center of the second coil.

15. The embedded package of claim 14, wherein a majority of a surface area of the first coil is not disposed directly opposite from a majority of a surface area of the second coil in the vertical direction.

16. The embedded package according to claim 11, further comprising an integrated circuit coupled to the first coil.

17. The embedded package according to claim 11, wherein, wherein the embedded package comprises a redistribution layer having only two conductive layers and at least one non-conductive layer disposed between the only two conductive layers, wherein the only two conductive layers comprise the first conductive layer and the second conductive layer.

18. The embedded package according to claim 11, further comprising:

at least one integrated circuit disposed over the second conductive layer; and

an encapsulating material disposed over the at least one integrated circuit.

19. A method of forming a transformer, the method comprising:

forming a second coil in a second conductive layer;

forming a first crossover in the second conductive layer;

forming a first coil in a first conductive layer over the second conductive layer, wherein the first conductive layer is disposed over the second conductive layer at a first distance; and

forming a second crossover in the first conductive layer, wherein;

the first coil comprises a first end disposed inside the first coil,

the second coil comprises a first end disposed inside the second coil,

the first crossover is coupled to the first end of the first coil and extends past an outer perimeter of the first coil, and

the second crossover is coupled to the first end of the second coil and extends past an outer perimeter of the second coil.

20. The method of claim 19, further comprising forming a first dielectric layer over the second conductive layer, wherein forming the first coil comprises forming the first coil over the first dielectric layer.

21. The method of claim 19, wherein:

forming the second coil further comprises forming the second coil on a first side of a first dielectric layer; and

forming the first coil comprises forming the first coil on a second side of the first dielectric layer opposite the first side.

22. The method of claim 21, wherein the first dielectric comprises a polymer material.

23. The method according to claim 19, further comprising forming an embedded package comprising only two conductive layers and at least one non-conductive layer that includes the first conductive layer and the second conductive layer, and a first dielectric layer disposed between the first conductive layer and the second conductive layer.