# US 2002/0149461 A1 · Apparatus and method for PCB winding planar magnetic devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2002/0149461 A1 - Document ID: US20020149461A1 - Status: Published application - Kind: A1 - Application number: 10/167,944 - Filed: 2002-06-11 - Published: 2002-10-17 - Earliest claimed: 2000-02-01 - Assignees: Compaq Computer Corporation - Inventors: Raoji A. Patel; James E. Drew; Raymond A. Pelletier; Brian R. McQuain - Web page: https://patentgrep.com/patent/US20020149461A1 ## CPC - H01F 27/2804: {Printed windings} - H01F 38/50: {Transformers for galvanic isolation} - H01F 41/041: {Printed circuit coils (apparatus or processes for manufacturing printed circuits in general H05K3/00)} - H05K 1/165: {incorporating printed inductors} - Y10T 29/4902: Electromagnet, transformer or inductor - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## 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 ### Claim 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. ### Claim 2 (depends on 1) The apparatus of claim 1 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. ### Claim 3 (depends on 2) 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. ### Claim 4 (depends on 1) 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. ### Claim 5 (depends on 4) 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. ### Claim 6 (depends on 1) 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. ### Claim 7 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. ### Claim 8 (depends on 7) The method of claim 7 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. ### Claim 9 (depends on 8) The method of claim 8 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.