Method for manufacturing a coil element assembly

Abstract

A coil module includes a coil conductor including a plurality of coil elements and a plurality of wire electrodes disposed on a circuit board, each of the plurality of coil elements including a pair of leg portions and a bridge portion connecting one end portions of the pair of leg portions together, the plurality of coil elements being disposed to cross a winding axis. A method for manufacturing the coil module includes an assembly forming step of integrating the plurality of coil elements with resin to form a coil element assembly, and a conductor forming step of mounting the coil element assembly on the circuit board to complete the coil conductor wound about the winding axis. In the conductor forming step, the resin is introduced into a die set in which the plurality of coil elements are arranged to form a block, to thus form the coil element assembly.

Claims

1. A method for manufacturing a coil element assembly comprising a coil conductor and a block, the coil conductor including a plurality of coil elements, each of the coil elements including a pair of leg portions and a bridge portion connecting end portions of the pair of leg portions together, the method comprising: an assembly forming step of forming the coil element assembly by integrating the plurality of coil elements together with a resin, wherein the assembly forming step comprises arranging the plurality of coil elements in a die set, and introducing the resin into the die set to form the block and to thus form the coil element assembly, wherein the resin is introduced so that a part of the bridge portion is covered with the block, and a remaining part of the bridge portion is exposed without being covered with the block.

2. The method according to claim 1, wherein a part of the leg portions is covered with the block, and a remaining part of the leg portions is exposed without being covered with the block.

3. A method for manufacturing a coil module comprising a coil element assembly and a plurality of wire electrodes, the coil element assembly comprising a coil conductor and a block, the coil conductor including a plurality of coil elements, the plurality of wire electrodes formed on a circuit board, each of the coil elements including a pair of leg portions and a bridge portion connecting end portions of the pair of leg portions together, the method comprising: an assembly forming step of forming the coil element assembly by integrating the plurality of coil elements together with a resin; and a conductor forming step of mounting the coil element assembly on the circuit board to complete the coil conductor wound about a predetermined winding axis, wherein the assembly forming step comprises arranging the plurality of coil elements in a die set, and introducing the resin into the die set to form the block and to thus form the coil element assembly, wherein the resin is introduced so that a part of the bridge portion is covered with the block, and a remaining part of the bridge portion is exposed without being covered with the block.

4. The method according to claim 3, wherein a part of the leg portions is covered with the block, and a remaining part of the leg portions is exposed without being covered with the block.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 illustrates a coil module according to an embodiment of the present disclosure.

(2) FIG. 2 is a cross-sectional view of a coil element of FIG. 1.

(3) FIG. 3 is a perspective view of a coil element assembly of FIG. 1.

(4) Each of FIGS. 4A and 4B illustrates a layout of a wire electrode of FIG. 1.

(5) FIG. 5 is an exploded perspective view of an existing coil module.

DETAILED DESCRIPTION OF THE DISCLOSURE

(6) A coil module 1 according to an embodiment of the present disclosure will be described with reference to FIG. 1 to FIGS. 4A and 4B. FIG. 1 is a perspective view of a coil module 1, FIG. 2 is a cross-sectional view of a coil element, FIG. 3 is a perspective view of a coil element assembly, and FIGS. 4A and 4B illustrate layouts of wire electrodes on the top surface and the back surface of a circuit board.

(7) As illustrated in FIG. 1, a coil module 1 according to the present embodiment includes a circuit board 2, multiple coil element assemblies 3 and a component 4 mounted on an upper surface 2a of the circuit board 2, and a sealing resin layer 5 that seals the coil element assembly 3 and the component 4. Together with multiple coil elements 6a and multiple wire electrodes 7a (refer to FIG. 4A) disposed on the upper surface 2a of the circuit board 2, the coil module 1 according to the present embodiment forms a coil conductor 6 that is wound about a winding axis WA. This coil conductor 6 functions as an antenna and is used as an antenna module for radio-frequency identification (RFID).

(8) The circuit board 2 is formed from, for example, a glass epoxy substrate or a ceramic substrate (for example, low temperature co-fired ceramic substrate, or LTCC substrate), and multiple wire electrodes 7a and 7b are laid out as illustrated in FIGS. 4A and 4B on an upper surface 2a and a lower surface 2b of the circuit board 2. The wire electrodes 7a and 7b are made of a material typically used for wire electrodes, such as Cu, Al, or Au.

(9) The component 4 is formed from a semiconductor device made of a semiconductor such as Si or GaAs, or a chip component such as a chip inductor, a chip capacitor, or a chip resistor. The component 4 is mounted on the circuit board 2 by a typical surface mount technology such as soldering.

(10) The coil conductor 6 includes multiple wire electrodes 7a disposed on the upper surface 2a of the circuit board 2, and the multiple coil elements 6a, constituting a part of the coil element assembly 3. Specifically, when the coil element assemblies 3 are mounted on the upper surface 2a of the circuit board 2, the wire electrodes 7a and substrate connection portions 6a3 (described later) of the respective coil elements 6a are connected together to form the coil conductor 6 that is helically wound about the winding axis WA. In the coil element assembly 3, the multiple coil elements 6a are integrated together with a resin-made block 8.

(11) The coil elements 6a have the same shape. Specifically, as illustrated in FIG. 2, each coil element 6a has a pair of leg portions 6a1, disposed substantially parallel to each other, and a bridge portion 6a2, which connects first end portions of both leg portions 6a1, and substrate connection portions 6a3, formed by bending the tips of second end portions of both leg portions 6a1 substantially 90°.

(12) The block 8 functions as a medium for fixing the coil elements 6a into an array. As illustrated in FIG. 3, a portion of the block 8 surrounded by both leg portions 6a1 and the bridge portion 6a2 of each coil element 6a is formed by being filled with resin. Specifically, the block 8 has no recess for accommodating the coil core, and has a portion surrounded by both leg portions 6a1 and the bridge portion 6a2 filled with resin. Both leg portions 6a1 of each coil element 6a are exposed from side surfaces 8a of the block 8 (refer to FIG. 3). The block 8 can be formed by, for example, thermoplastic resin such as a liquid crystal polymer, or thermosetting resin.

(13) The coil elements 6a are fixed to the block 8 with both leg portions 6a1 and the bridge portion 6a2 disposed at such positions as to cross the winding axis WA. Specifically, in the state where the coil element assemblies 3 are mounted on the circuit board 2, the coil elements 6a are arranged in the direction parallel to the winding axis WA and fixed while each having one of the leg portions 6a1 disposed on one side of the winding axis WA of the coil conductor 6 and the other leg portion 6a1 disposed on the other side of the winding axis WA (refer to FIG. 1 and FIG. 3). The substrate connection portions 6a3 of the coil elements 6a are left without being covered with the block 8, and serve as connection portions when the coil element assemblies 3 are mounted on the circuit board 2.

(14) Each wire electrode 7a disposed on the upper surface 2a of the circuit board 2 is paired with the corresponding one of the coil elements 6a. Each wire electrode 7a connects the substrate connection portion 6a3 connected to a first one of the leg portions 6a1 of the paired coil element 6a, and the substrate connection portion 6a3 connected to a second one of the leg portions 6a1 of a coil element 6a adjacent to the paired coil element 6a. This connection structure between the coil elements 6a and the wire electrodes 7a forms a coil conductor 6 that is wound about the winding axis WA.

(15) The sealing resin layer 5 seals the coil element assemblies 3 and the component 4, and is stacked on the upper surface 2a of the circuit board 2. The sealing resin layer 5 is made of general sealing resin such as epoxy resin.

(16) (Method for Manufacturing Coil Module)

(17) A method for manufacturing a coil module 1 will be described below. Each coil element 6a is formed by subjecting one metal plate (such as a Cu plate) to a cutting process and a bending process. Specifically, one metal plate is cut into a shape where the coil elements 6a (before being bent) are arranged equidistantly and parallel to each other.

(18) Then, each coil element 6a subjecting to the cutting process is bent to form the pair of leg portions 6a1, the bridge portion 6a2, and the substrate connection portions 6a3.

(19) Subsequently, while the coil elements 6a subjected to the bending process are arranged in a die set having the shape corresponding to the shape of the block 8, resin is introduced into the die set to form the block 8, and to thus form the coil element assembly 3. At this time, a part of the leg portions 6a1, a part of the bridge portion 6a2, and the substrate connection portions 6a3 of each coil element 6a are exposed without being covered with the block 8 (refer to FIG. 3). Resin is filled in a space surrounded by the leg portions 6a1 and the bridge portions 6a2 to form the block 8.

(20) Subsequently, the coil element assemblies 3 are mounted on the upper surface 2a of the circuit board 2 to complete the coil module 1. At this time, the substrate connection portions 6a3 of each coil element 6a are connected with solder to the end portions of the corresponding wire electrodes 7a to form the coil conductor 6 helically wound about the winding axis WA. The circuit board 2 can be formed by a general method for forming a circuit board. The procedure of mounting the coil element assemblies 3 and the component 4 on the circuit board 2 may be performed in any order; the coil element assembly 3 may be mounted after the component 4 is mounted, or the component 4 may be mounted after the coil element assemblies 3 are mounted.

(21) Thus, in the above embodiment, to form an assembly (coil element assembly 3) of the coil elements 6a constituting a part of the coil conductor 6, resin is introduced into the die set, in which the multiple coil elements 6a are arranged, to form the block 8. This procedure can omit forming of through-holes in the block to allow the coil elements to be arranged or fixed thereto, unlike in the existing procedure, and thus the coil module 1 can be manufactured at lower costs. In a structure where the support body 104 has the through-holes 104b, as in the existing coil module 100 (refer to FIG. 5), the through-holes 104b need to be spaced apart at a predetermined distance or longer to prevent adjacent through-holes 104b from connecting to each other. Thus, the pitch between the through-holes 104b cannot be narrowed beyond a certain limit. In the coil module 1 according to the present embodiment, on the other hand, the coil elements 6a can be arranged at a narrower pitch since the block 8 (corresponding to “the support body 104” in an existing technology) has no through-holes. In addition, unlike the existing coil module 100 (refer to FIG. 5), the coil module 1 according to the present embodiment does not degrade the positioning accuracy due to the play of the through-holes 104b, such as tilting of the coil elements 6a. Thus, the coil module 1 having preferable coil characteristics can be manufactured. The coil elements 6a that stand without being tilted improve the mount yield of the coil element assembly 3.

(22) Each of the coil elements 6a has the substrate connection portions 6a3 formed by bending the tips of the second end portions of both leg portions 6a1 by 90°. Compared to a structure where the coil elements 6a are connected to the circuit board 2 without having the tips of the second end portions of both leg portions 6a1 bent, the contact area between themselves and the circuit board 2 increases. This structure can thus improve the reliability in connection between the coil element assembly 3 and the circuit board 2, and improve the mount yield of the coil element assembly 3.

(23) The present disclosure is not limited to the above-described embodiments, and can be changed in various different manners other than the above without departing from the gist of the disclosure.

(24) For example, each coil element 6a may have any shape, such as a letter-U shape, that can form a helical coil conductor.

(25) The present disclosure is widely applicable to various types of coil modules including a coil conductor partially formed from a wire electrode of a circuit board.

(26) 1 coil module

(27) 2 circuit board

(28) 3 coil element assembly

(29) 4 component

(30) 6 coil conductor

(31) 6a coil element

(32) 6a1 leg portion

(33) 6a2 bridge portion

(34) 7a, 7b wire electrode

(35) 8 block