Apparatus and method for pcb winding planar magnetic devices

• US 20020057171A1
• Filed: 02/01/2000
• Published: 05/16/2002
• Est. Priority Date: 02/01/2000
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Patel, Raoji A., Pelletier, Raymond A., Drew, James E., McQuain, Brian R.
• Granted Patent: US 6,429,763 B1
• Time in Patent Office: Days
• US Class Current: 336/200
• CPC Class Codes: H01F 2019/085 Transformer for galvanic isolation
• 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: H05K 1/165 incorporating printed inductors
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

A method and apparatus to layout planar magnetic coils on a PCB consists of maximizing the layer to layer overlap, and consequently maximizing total inductance for the given layout area, by spiraling alternating layers inward and outward. A further benefit of the matching opposite spirals is the ability to make the layer to layer electrical contacts within the magnetic field area, thus reducing leakage inductance, and minimizing the wasted extra conductor line length needed to make the connections outside the magnetic field. The reduced conductor line length results in reduced conductor line resistance. The method is applicable to voltage transformers and isolation transformers as well as simple inductors and other magnetic devices. In the transformer case the odd numbered layers are typically connected together in series to provide a larger turn ratio, and the even numbered layers are typically single turns (i.e., no spiral) connected together in parallel to provide more current capability.

Claims

1. An apparatus for providing a voltage transformation, comprising:

a PCB having a plurality of conductive layers electrically separated by a plurality of insulating layers, and a plurality of conductive vias connecting the conductive layers at selected locations;

a plurality of primary windings having a specified order;

a plurality of secondary windings having a specified order; and

wherein a first one of the plurality of primary windings is disposed on a first one of the plurality of conductive layers of the PCB, a first one of the secondary windings is disposed upon a second one of the plurality of conductive layers of the PCB, a second one of the plurality of primary windings is disposed upon a third one of the plurality of conductive layers of the PCB, a second one of the plurality of secondary windings disposed upon a fourth one of the plurality of conductive layers of the PCB, continuing until each individual one of the plurality of primary and plurality of secondary windings is disposed upon a separate one of the plurality of conductive PCB layers.

4. The apparatus of claim 1 wherein the plurality of conductive PCB layers is smaller than the plurality of primary and secondary windings, and the remaining individual ones of the primary and secondary windings are disposed upon at least a second multilayered PCB disposed upon a face of the PCB and having electrical communication with the PCB.

5. The apparatus of claim 4 wherein further at least a third multilayered PCB is disposed upon the opposite face of the PCB from the at least second PCB, and having electrical communication with the PCB.

6. The apparatus of claim 1 wherein an end of the first primary coil is electrically connected to an end of the second primary coil using a selected one of the plurality of vias.

2. The apparatus of claim one wherein further the odd numbered primary windings spiral inward toward a core region in one of either a clockwise or counter clockwise direction;

the even numbered primary windings spiral outward from the core region in the same direction as the odd numbered primary windings;

the odd numbered secondary windings spiral inward toward the core region in the same direction as the primary windings; and

the even numbered secondary windings spiral outward from the core region in the same direction as the primary windings.

3. The apparatus of claim 2 wherein the odd numbered secondary windings spiral outward from the core region, and the even numbered secondary windings spiral inward.

7. An apparatus for planar magnetic windings on a PCB, comprising:

a plurality of electrical conductor lines formed into planar coils;

wherein selected ones of the plurality of coils spiral inward; and

wherein selected ones of the plurality of coils spiral outward.

8. The apparatus of claim 7 wherein further both of the pluralities of coils spiral in a clockwise direction.

9. The apparatus of claim 7 wherein further the planar coils are disposed upon different conductive layers of the PCB in a vertical stack having alternating inward and outward spirals interleaved.

10. The apparatus of claim 9 wherein the electrical connections between coils disposed upon different PCB layers are made inside a magnetic field area.

11. The apparatus of claim 10 wherein the magnetic field is produced by the action of electric current changes in the plurality of coils.

12. The apparatus of claim 9 wherein the PCB has the number of conductive layers increased by the addition of a plurality of daughter boards attached to and in electrical communication with the PCB.

13. The apparatus of claim 12 wherein the plurality of daughter boards are attached to the PCB in pairs on opposite sides of the PCB.

14. The apparatus of claim 9 wherein the odd numbered ones of the plurality of coils are each electrically connected together to form the primary windings of a transformer, and the even numbered ones are electrically connected together to form the secondary windings of the transformer.

15. The apparatus of claim 14 wherein alternate ones of the odd numbered coils are spirals inward toward a central core area, the remaining ones of the odd numbered coils are spirals outward in the same direction as the inward spirals, and all of the even numbered coils are single turn coils.

17. The method of claim 16 wherein the first and third coils are connected in series, the second and fourth coils are connected in parallel, and all of the coil to coil via connections are within the magnetic field area of the coils.

18. The method of claim 17 wherein further there are a plurality of pairs of coils disposed similarly directly below, and connected in series to, the first and third coils;

and

a plurality of pairs of coils disposed similarly directly below, and connected in parallel to the second and fourth coils.

16. A method for winding conductors for providing magnetic fields on a PCB having a plurality of conductive layers, comprising the steps of:

winding a first coil having an inward clockwise spiral with a specified number of turns toward a central core on a first conductive layer of the PCB, terminating the inward spiral at an electrical via connection passing through a second conductive layer without making electrical contact, and making electrical contact to a third conductive layer;

winding a second coil having a single turn on the second conductive layer of the PCB, and terminating the winding at an electrical via passing through the third layer without making electrical contact, and making electrical contact to a fourth conductive layer of the PCB;

winding a third coil having an outward clockwise spiral with a specified number of turns away from the central core on an area of the third conductive layer of the PCB which is disposed to be directly underneath the location of the first coil; and

winding a fourth coil having a single turn on the fourth conductive layer of the PCB on an area of the fourth conductive layer that is disposed to be directly underneath the second coil.