# US 2013/0278374 A1 · Coil assembly comprising planar coil > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0278374 A1 - Document ID: US20130278374A1 - Status: Published application - Kind: A1 - Application number: 13/978,191 - Filed: 2012-01-04 - Published: 2013-10-24 - Earliest claimed: 2011-01-04 - Assignees: ÅAC Microtec AB - Inventors: Robert Thorslund - Web page: https://patentgrep.com/patent/US20130278374A1 ## CPC - H01F 27/2804: {Printed windings} - H01F 27/29: Terminals; Tapping arrangements {for signal inductances} - H01F 41/041: {Printed circuit coils (apparatus or processes for manufacturing printed circuits in general H05K3/00)} - H01F 41/046: {structurally combined with ferromagnetic material} - H01F 2017/0066: {with a magnetic layer} - Y10T 29/4902: Electromagnet, transformer or inductor - Y10T 29/49071: by winding or coiling - Y10T 29/49073: by assembling coil and core - Y10T 29/49075: including permanent magnet or core - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Coil assembly (1) comprising a planar coil (2) comprising a plurality of turns (15) arranged in a trench (10) in a first magnetic core plate (3) and a second magnetic core plate (8), where the first magnetic core plate (3) and second magnetic core plate (8) are in direct contact with each other or separated by an electrically insulating insulator layer (5) with a thickness (t) equal to or less than 50 μm and least one tap (6) extends from the coil (2) in a respective via hole (11) through the first magnetic core plate (3) to a respective contact pad (7), wherein the coil (2) and the tap (6) are integrally formed. ## Claims ### Claim 1 Surface mountable coil assembly (1) comprising a planar coil (2) comprising a plurality of turns (15) arranged in a trench (10) in a first magnetic core plate (3), and a second magnetic core plate (8), wherein the first magnetic core plate (3) and second magnetic core plate (8) are in direct contact with each other or separated by an electrically insulating insulator layer (5) with a thickness (t) equal to or less than 50 μm and least one tap (6) extends from the coil (2) in a respective via hole (11) through the first magnetic core plate (3) to a respective contact pad (7), characterized in that the coil (2) and the tap (6) are integrally formed. ### Claim 2 (depends on 1) A coil assembly according to claim 1, characterized in that the at least one tap (6) is integrally formed with its respective contact pad (7). ### Claim 3 (depends on 1) A coil assembly according to claim 1, characterized in that the height (h) of turns (15) of the coil (2) is in the range of more than 100 μm up to 1100 μm. ### Claim 4 (depends on 1) A coil assembly according to claim 1, characterized in that the height (h) of turns (15) of the coil (2) is in the range of more than 150 μm to 1100 μm. ### Claim 5 (depends on 1) A coil assembly according to claim 1, characterized in that the height (h) of turns (15) of the coil (2) is in the range of more than 200 μm up to 1100 μm. ### Claim 6 (depends on 1) A coil assembly according to claim 1, characterized in that the width (W) of the turns (15) of the trench (10) is in the range of 50 μm to 1000 μm. ### Claim 7 (depends on 1) A coil assembly according to claim 1, characterized in that the width (W) of the turns (15) of the trench (10) is in the range of 200 μm to 800 μm. ### Claim 8 (depends on 1) A coil assembly according to claim 1, characterized in spacing (S) between the turns (15) of the trench (10) is in the range of 50 μm to 1000 μm. ### Claim 9 (depends on 1) A coil assembly according to claim 1, characterized in that the thickness (T1) of the first magnetic core plate (3) in the range of more than 100 μm up to 4000 μm larger than the depth (H) of the trench (10). ### Claim 10 (depends on 1) A coil assembly according to claim 1, characterized in that the coil (2) comprises a first coil member (414, 514) comprising at least two turns, and a second coil member (415, 515) comprising at least two turns, wherein second magnetic core plate (408, 508) extends in between the turns of said second coil member (415, 515), said second coil member (415, 515) being electrically connected to the turns of first coil member (414, 514) in between which the first magnetic core plate (3) extends. ### Claim 11 (depends on 1) A coil assembly according to claim 1, characterized in that at least the first magnetic core plate (3) or the second magnetic core plate (8) has a recess providing space for the coil (2). ### Claim 12 (depends on 1) A coil assembly according to claim 1, characterized in that an air gap (313) is present in the centre of the planar coil (302) between the first magnetic core plate (303) and the second magnetic core plate (308). ### Claim 13 (depends on 1) A coil assembly according to claim 1, characterized in that the respective via hole (11) has a varying cross section over the length of the via hole (11) from the side (m1) of the first magnetic core plate (3) where the trench (10) is present to the opposite side (m2) of the first magnetic core plate (3). ### Claim 14 (depends on 1) A coil assembly according claim 1, characterized in that the respective via hole (11) is wider both towards the side (m1) of the first magnetic core plate (3) where the trench (10) present and towards the opposite side (m2) of the first magnetic core plate (3) than in the interior of the via hole. ### Claim 15 (depends on 1) A coil assembly according to claim 1, characterized in that the trench (10) has sloping sidewalls. ### Claim 16 Magnetic core plate comprising a trench (10) in which a planar coil (2) comprising a plurality of turns (15) is arranged, wherein least one tap (6) extends from said coil (2) in a respective via hole (11) through said magnetic core plate (3) to a respective contact pad (7), characterized in that the coil (2) and the tap (6) are integrally formed. ### Claim 17 (depends on 1) A transformer, characterized in that it comprises at least one coil assembly according to claim 1. ### Claim 18 (depends on 17) A transformer according to claim 17, characterized in that it comprises two planar coils (618, 818, 619, 819) in the first magnetic core plate (603, 803). ### Claim 19 (depends on 18) A transformer according to claim 18, characterized in that the planar coils (618, 619) are arranged in an interleaving pattern. ### Claim 20 (depends on 18) A transformer according to claim 18, characterized in that the planar coils (818, 819) are arranged in a radially sequential pattern. ### Claim 21 (depends on 17) A transformer according to claim 17, characterized in that the first magnetic core (903, 1003) plate comprises a first planar coil (918, 1018) and the second magnetic core plate (908, 1008) comprises a second planar coil (919, 1019) ### Claim 22 (depends on 1) A method of manufacturing a device according to claim 1, characterized in that it comprises the following steps: providing a first magnetic core plate (3), preferably with a thickness (T1) more than 200 μm up to 5000 μm, providing a trench (10) in the form of a turn (15) pattern with a trench depth (H) preferably in the range of 100 μm to 1000 μm, a width (W) of the turns (15) of the trench (10) preferably in the range of 50 μm to 1000 μm, even more preferably in the range of 200 μm to 800 μm, and spacing (S) between the turns (15) of trench (10) preferably in the range of 50 μm to 1000 μm in the first the magnetic core plate (3) and via holes (11) through the first magnetic core plate (3) for example by milling, sand blasting, water jetting, the ratio of the width (W) of the turns (15) of the trench (10) to the depth (H) of the trench (10) is 1:1.2 to 1:20 and more preferably 1:2 to 1:5, the thickness (T1) of the first magnetic core plate (3) is preferably in the range of more than 100 μm up to 4000 μm thicker than the depth (H) of the trench (10). providing an insulator layer (5) covering at least the bottom of trench (10) and a substantial part of the sidewalls of the trench (10) as well as the sidewall of each via hole (11) and, preferably, the insulator layer (5) is deposited conformally on all surfaces, using for example chemical vapour deposition of poly(p-xylylene) polymers (e.g. Parylene™), and the preferred thickness (t) of the insulator layer (5) is in the range of 1 μm to 50 μm, providing a seed layer (12) in the trench of preferably Ti—Cu, TiW—Cu but it could also be other types of metal, of a total thickness of the seed layer (12) preferably in the range of 100 nm to 700 nm, providing coil conducting material (4), preferably Cu, by electroplating, filling the trench (10) and the via holes (11) in the same stage, the height (h) of coil conducting material (4) of the turns of the coil (2) is preferably in the range of more than 100 μm up to 1100 μm, more preferably in the range of more than 150 μm up to 1100 μm, and even more preferably in the range of more than 200 μm up to 1100 μm. providing a second magnetic core plate (8) with preferably a thickness (T2) in the range of 50 μm to 4000 μm. providing a recess (9) in the second magnetic core plate, mounting the second magnetic core plate (8) on the first magnetic core plate (3) using for example gluing, mechanical clamping or soldering. ### Claim 23 (depends on 22) A method according to claim 22, characterized in that coil conducting material (4) is also provided on the side (m2) of the first magnetic core plate (3) which is opposite to the side (m1) of the first magnetic core plate (3) where the trench (10) is present. ### Claim 24 (depends on 22) A method according to claim 22, characterized in that the seed layer (12) is deposited through a shadow mask.