JPH08222829A - Structure for mounting thin band coil on printed board - Google Patents

Abstract

PURPOSE: To stabilize the height of a thin band coil when the coil is mounted on a printed board and, at the same time, to reduce the cost of the coil by improving the manufacturing efficiency of the coil. CONSTITUTION: A thin band coil 33 is put on a printed board 1 in such a state that the coil 33 is brought into contact with the insulating section 13 of the board 1 and at least part of the section 13 is interposed between a wiring layer 12 for feeding and the side face of the coil 33 as the bridge section 13a of a conducting material 34 by protruding the part outward from the side face of the coil 33 or flushing the part with the side face of the coil 33. At the time of connecting a connection pad 22 constituting part of the wiring layer 12 to the side face of the coil 33 with the conducting material 34, the bridge section 13a having an insulating property is interposed between the pad 22 and the side face of the coil 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for mounting a ribbon coil, which is formed by winding a plurality of ribbon-shaped conductive foils, on a printed circuit board. More specifically, at least one of the end faces of the thin coil is placed on the printed circuit board,
The present invention relates to an improvement in a structure for mounting a ribbon coil on a printed board in which a power supply wiring layer of the printed board and a side surface of the ribbon coil are connected by a conductive material.

[0002]

2. Description of the Related Art Conventionally, a ribbon coil is attached to a printed circuit board by connecting a side surface of the ribbon coil and a power supply wiring layer of the printed circuit board with a conductive material such as solder. At the time of connection by this solder, the solder wraps around to the end face side of the thin strip coil placed on the printed circuit board, melts the insulating agent coated on the end face, and makes an electrical short circuit for several to several tens of turns. It may happen. Therefore, in order to prevent this electrical short circuit, it has been considered to apply a heat resistant insulating layer having a heat resistant temperature higher than the melting temperature of the solder to the end surface of the thin coil (actual fair 2-275).
23).

[0003]

However, in the conventional mounting structure of the ribbon coil to the printed board, the ribbon coil is placed in a state of being in contact with the conductive portion of the printed board. Flows along the conductive portion and easily flows into the end surface of the ribbon coil. Therefore, in order to prevent an electrical short circuit between the conductive part and the end face of the ribbon coil, in addition to the adhesive that is applied to temporarily bond the ribbon coil to the printed circuit board, it is applied in advance to the end face of the ribbon coil. A heat resistant insulating layer is required. As a result, the height of the ribbon coil when attached to the printed circuit board tends to vary. Moreover, the heat-resistant insulating layer is made of the same material as the adhesive, and the same material is applied twice to the end surface of the ribbon coil. For this reason, it takes time and labor, the manufacturing efficiency is lowered, and the cost is increased.

The present invention provides a structure for mounting a thin strip coil on a printed circuit board, which stabilizes the height of the thin strip coil when mounted on the printed circuit board, and further improves the manufacturing efficiency and reduces the cost. The purpose is to provide.

[0005]

In order to achieve the above object, in the invention according to claim 1, at least one of the end faces of the thin strip coil is placed on a printed circuit board, and the power supply wiring layer of this printed circuit board and a thin layer are provided. In a structure for mounting a thin coil on a printed circuit board by connecting a side surface of the coil with a conductive material, the thin coil is placed in contact with an insulating portion of the printed circuit board, and at least a part of this insulating portion is placed. Is projected outward from the side surface of the ribbon coil or is flush with the side surface, and that portion is interposed as a bridging portion of a conductive material between the power supply wiring layer and the side surface of the ribbon coil.

According to the second aspect of the invention, at least one of the end faces of the thin strip coil is placed on the printed circuit board, and the power supply wiring layer of this printed circuit board and the side face of the thin strip coil are connected by a conductive material. In the mounting structure of the ribbon coil on the printed circuit board, the ribbon coil is placed in contact with the insulating portion of the printed circuit board, and the side surface of the ribbon coil and the insulating portion are placed at a temperature higher than the melting temperature of the conductive material. It is fixed by an adhesive having a high melting temperature, and this adhesive is interposed as a bridging portion of the conductive material between the power supply wiring layer and the side surface of the ribbon coil.

[0007]

Therefore, according to the first aspect of the present invention, the thin strip coil in which a plurality of thin strip-shaped conductive foils are wound is placed as it is on the insulating portion of the printed circuit board with the end face down. Then, the insulating portion is projected outward from the side surface of the ribbon coil or is flush with the side surface, and the portion is interposed as a bridging portion of a conductive material between the power supply wiring layer and the side surface of the ribbon coil, Since the power supply wiring layer of the printed circuit board and the side surface of the ribbon coil are connected by the conductive material, the conductive material does not wrap around to the end surface of the ribbon coil.

According to the second aspect of the invention, the thin strip coil formed in the same manner as in the first aspect is mounted on the insulating portion of the printed circuit board with the end face down. Then, the side surface of the thin strip coil and this insulating portion are fixed to each other with an adhesive having a melting temperature higher than the melting temperature of the conductive material, and this adhesive is used as a bridging portion of the conductive material to connect the power supply wiring layer and the side surface of the thin strip coil. Since the power supply wiring layer of the printed circuit board and the side surface of the ribbon coil are connected by a conductive material, the conductive material does not wrap around to the end surface of the ribbon coil.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 and FIG. 2 show an embodiment of a structure for mounting the ribbon coil of the present invention on a printed board. This mounting structure has a flexible wiring board (FPC) 1 in which a power supply wiring layer 12 made of copper foil is formed on a base 11 made of strip-shaped polyimide resin, and a thin strip coil fixed on the flexible wiring board 1. And 33. The flexible wiring board 1 is a so-called printed circuit board. As shown in FIG. 1, a power supply wiring layer 12 is formed by printing on a base 11, and an insulating resist (insulating portion) 13 is coated thereon. Part of it is resist 1
The connection pad 22 is not covered by 3. The connection pad 22 constitutes a part of the power supply wiring layer 12.

The thin coil 33 is formed by first coating one or both surfaces of a conductive film, such as a metal foil 36 such as a copper foil, with a resin electrical insulator layer 38 and a resin adhesive layer 39, and using this as a core jig. A rod-shaped wound body is formed by winding the wire around the wire. Here, the electric resin insulation layer 38 and the resin adhesive layer 39 constitute the electric insulation layer 37. The wound body is completely adhered and solidified by heating or ultraviolet curing the resin adhesive layer 39 in the firing step, and then the winding jig is removed and the wound body is sliced with a wire saw or the like to be thinned. The strip coil 33 is formed. Of course, the ribbon coil 33 may be obtained by winding a ribbon of a conductive material having a predetermined width. In this embodiment, the resin electric insulator layer 38 is coated only on one surface of the metal foil 36, and the resin adhesive layer 39 has an insulating property. After being sliced, burrs are removed by etching or the like in order to prevent a short circuit at the coil end surface (cut end).

The thin coil 33 is manufactured by a step of coating the metal foil 36 with the resin layers 38 and 39, and by baking the coated metal foil 36 temporarily at about 80 to 150 ° C. Semi-curing, winding the core around a winding jig to form a wound body, and winding the wound body to 120 to 20.
This is performed by the steps of main firing at 0 ° C. and slicing the wound body. In addition, a high-density electrical insulator layer 38 of PAI (polyamideimide) resin having a thickness of about 1 μm is formed on one surface of the metal foil 36, and a semi-curable and insulating material is formed on one surface or the other surface of the metal foil 36. Resin adhesive layer 39
Is coated to a thickness of about 1 μm, it is possible to suppress the thickness of the electrical insulator layer 38 and the resin adhesive layer 39 while avoiding insulation failure due to the occurrence of pinholes and the like. However, in this case, as long as the resin adhesive layer 39 can be made sufficiently thin, an adhesive having another insulating property may be used instead of the semi-curable resin. The resin adhesive layer 39
As for, not a semi-curable resin, but a nylon-based, polyolefin-based, thermoplastic resin such as ester imide,
A method of hardening the wound body by curing may be adopted.

The wound body formed in this way is, for example, 0.
Slice to a thickness of 15-0.30 mm. Then, the end face (cut) of the sliced thin ribbon coil 33 is attached onto the resist 13 of the flexible substrate 1. For this attachment, first, the ribbon coil 33 is press-molded using a mold formed in conformity with the shape of the ribbon coil 33. Next, the insulating film on the surface of the winding end existing on the inner peripheral surface and the outer peripheral surface of the thin strip coil 33 is physically attached by polishing or the like corresponding to the position of the connection pad 22 formed on the surface of the flexible wiring board 1. The thin strip coil 33 having the connection surface portions 33d and 33e is formed by removing it by chemical treatment such as chemical treatment or etching.

Flexible wiring board 1 of thin coil 33
The fixing to the top is performed as shown in FIGS. 1 and 2. First, the outermost layer and the innermost layer of the thin strip coil 33, to which the surface portions 33d and 33e to be connected are arranged on or in the vicinity of the connection pad 22 of the flexible wiring board 1, the adhesive agent of the thin strip coil 33 is formed. The end surface to which 35 is applied is arranged in contact with the insulating portion / overcoat 13 of the flexible wiring board 1. That is, they are arranged so that the connection pad 22 is located slightly inside the connection surface portion 33d or the connection pad 22 is located slightly outside the connection surface portion 33e. Then, the resist 13, which is an insulating portion, is formed so as to project slightly outward from the connection surface portions 33d and 33e. This protruding portion serves as a bridging portion 13a of the conductive material, for example, the solder 34. It should be noted that the resist 13 is not slightly projected to the outside and the resist 13 is made to be flush with the surfaces of the connection surface portions 33d and 33e.
However, also in that case, the side surface of the resist 13 serves as a bridging portion.

Then, the connection pad 22 and the thin strip coil 33.
The bridge portion 13a is interposed between the side surface of the
The connection pad 22 and the side surface of the ribbon coil 33 are connected by a conductive material such as solder 34. This connection is called a so-called bridge connection (a connection between terminals such as soldering is performed with a non-conducting portion interposed between them, which is connected as if it were a bridge). Is. As a specific method of this connection, for example, as shown in FIG. 2A, the cream solder 34 is applied from the nozzle 8 having the outlet port facing the connection surface portion 33e.
Then, the cream solder 34 is melted by a reflow process, and is made to flow down along the bridging portion 13a of the resist 13 and flown on the connection pad 22 as shown in FIG. 2B. Therefore, the connection surface portion 33
e is to be naturally connected to the connection pad 22. Here, a conductive paste such as silver wax can also be used as the conductive material. In this case, the conductive paste is used as the connection surface portion 33.
It is applied between d and 33e and the connection pad 22 or dropped from the nozzle 8. In this way, the connection process can be automated, and since reliable conductive connection can be made, connection failure, disconnection accident, etc. can be prevented.

As described above, when the connection pad 22 and the side surface of the ribbon coil 33 are connected, the conductive material, for example, the solder 34 is formed via the bridging portion 13a having an insulating property. Since it does not go around to the end face of the thin ribbon coil 33, an electrical short circuit does not occur. Further, since a heat-resistant insulating layer as in the conventional case is not required, the height H of the thin strip coil 33 from the surface of the flexible wiring board 1 when attached to the flexible wiring board 1 which is a printed circuit board.
Does not vary. Moreover, the same kind of material is never applied to the end surface of the thin ribbon coil 33, the manufacturing efficiency is improved, and the cost can be reduced.

Next, FIG. 3 shows an example in which the structure for mounting the thin strip coil of the present invention on a printed circuit board is applied to a coil unit used in an optical pickup device. 1 and 2
The same reference numerals as in FIG.

The coil unit of this optical pickup device includes a flexible wiring board (FPC) 1 in which a power supply wiring layer 12 made of a plurality of copper foils is formed on a base 11 made of strip-shaped polyimide resin, and the flexible wiring board 1. 1 is composed of a pair of thin ribbon coils 33 shown in FIG. 1, which are fixed to each other, and a focusing drive coil 31, 31 and a pair of thin ribbon coils 33, which are similarly fixed to each other, for tracking. Has been done. In this flexible wiring board 1, as shown in FIG. 3, a power supply wiring layer 12 is formed by printing on a base 11, and an insulating resist (insulating portion) 13 is coated on the power supply wiring layer 12.
Further, each ribbon coil is the same as that of the embodiment shown in FIG.

In the center of the flexible wiring board 1, a thin terminal portion 1a is formed, and the end portions of the power supply wiring layer 12 are centrally arranged therein, and in addition, a plurality of terminals not covered with the resist 13 are provided. Input pad 20 is formed. The other ends of the power supply wiring layer 12 are arranged inside and outside the focus drive coil 31 and the tracking drive coil 32, respectively, and the connection pads 21 and 22 not covered with the resist 13 are formed. The connection pads 21 and 22 are connected to the power supply wiring layer 1
It forms part of 2.

The end face (cut) of the thin ribbon coil 33
Is attached on the resist 13 of the flexible substrate 1 to form the focus drive coil 31 and the tracking drive coil 32. For this attachment, first of all, this thin coil 3
The ribbon coil 33 is press-molded by using a mold formed according to the shape of 3. This molding process is performed by, for example, the focus drive coil 31 and the tracking drive coil 32.
When the mounting surface of 1 is a curved surface, die molding is performed so that the end surface of the thin ribbon coil 33 has a similar curved surface. The slice thickness of each drive coil 31, 32 formed in this way is
It becomes 0.15-0.30 mm. The thickness of the flexible wiring board 1 is about 0.13 mm, and the total thickness of the coil unit 10 is in the range of 0.30 to 0.45 mm. In addition, when slicing the wound body, it is also possible to cut so that the end surface has the same shape as the mounting surface.

Finally, the insulating film on the surface of the winding end existing on the inner peripheral surface and the outer peripheral surface of the thin coil 33 is made to correspond to the positions of the connection pads 21 and 22 formed on the surface of the flexible wiring board 1. By removing by a physical treatment such as polishing or a chemical treatment such as etching, the connection surface portion 3
The tracking drive coil 32 including 2d and 32e is formed. The focusing drive coil 31 is similarly processed to form the connection surface portions 31d and 31e.

The focus drive coils 31 and 31 and the tracking drive coil 32 formed in this manner
32 is attached by an adhesive 35 or the like so that the end face formed in a shape matching the mounting surface is aligned with the surface of the flexible wiring board 1 in correspondence with the positions of the connection pads 21, 22.

The focusing drive coils 31, 31 and the tracking drive coils 32, 32 are fixed to the flexible wiring board 1 in the same manner as shown in FIGS.

When the present invention is applied to the coil unit 10 of the optical pickup device as shown in FIG. 3, the thickness of the coil unit 10 as a whole is stable, and the focusing drive coils 31 and 31 and the tracking drive coils 32 and 32 are formed. The gap between the magnet and the corresponding magnet can be made stable with very little variation, which stabilizes the drive characteristics of the optical pickup device and facilitates the manufacture.

The above embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, as shown in FIG. 4, the thin coil 33 whose end surface is not coated with the heat-resistant insulating layer is attached to the insulating portion 1 of the printed circuit board 1.
3 with its end surface in contact with the thin coil 33
Of the conductive material 34 is fixed to the side surface of the conductive material 34 with an adhesive 35 having a melting temperature higher than that of the conductive material 34.
May be interposed as a bridging portion of the conductive material 34, and the connection pad 22 and the side surface of the ribbon coil 33 may be connected by the conductive material 34. This connection method is also a kind of bridge connection. According to this structure, the adhesive 35 can further prevent the conductive material 34 from wrapping around the contact portion 40. Further, since the thin strip coil 33 can be adhered to the printed circuit board 1 without the adhesive entering the contact portion 40,
The variation in the height H of the thin ribbon coil 33 is further reduced.
However, even if the adhesive 35 is applied to the side surface 41 of the contact portion 40, the adhesive is applied to either the surface of the resist 13 or the end surface of the thin ribbon coil 33 so that the adhesive enters the contact portion 40. good. In this case, the advantage in the variation of the height H of the thin strip coil 33 is lower than that in the case where the adhesive does not enter the contact portion 40, but the advantage that the variation is less than that in the conventional one is less. Still held.

Further, as shown in FIG. 5, the bridging portion 13 of the resist 13 around the electrode hole 42 where the connection pad 22 is exposed.
A rising portion 13b is provided on a. Then, the thin strip coil 33 whose end face is not coated with the heat resistant insulating layer may be arranged so that one or both of the connection surface portions 33d and 33e are along the rising portion 13b. In addition,
The end face not coated with the heat-resistant insulating layer is placed on the resist 13 as in the embodiment shown in FIGS. 1 and 4. Due to the presence of the rising portion 13b, the conductive material 34 forms a bridge connection along the rising portion 13b, further preventing the conductive material 34 from wrapping around the contact portion 40 and positioning the rising portion 13b on the ribbon coil 33. Can be used for

Further, FIG. 6 shows another embodiment. In this embodiment, the O-ring 1 is used instead of the rising portion 13b in FIG.
3c is adopted. In this case, as shown in FIG. 6B, the O-ring 13c is fitted around the ribbon coil 33 and pushed down until it comes into contact with the resist 13, so that the connection surface portion 33e of the ribbon coil 33 and the connection pad 22 are separated. It is possible to prevent the conductive material 34, such as solder, which is electrically connected, from wrapping around around the contact portion 40. Reference numeral 43 is an insulating sheet.

Here, as the conductive material used in the bridge connection as in each of the embodiments, a high viscosity type material is desirable from the viewpoint of forming a bridged state and preventing wraparound.

It is not always necessary to apply a B-stage agent having both adhesive and insulating functions to the end face of the thin strip coil 33, place it on the insulating portion 13 of the printed circuit board 1, and then carry out curing treatment. It is not necessary to form the bridging portion 13a in the insulating portion 13, and it is not necessary to form the conductive material 34 via the adhesive 35 attached to the side surface of the contact portion 40 as shown in FIG. Further, by combining any one or a plurality of the configurations shown in FIG. 1, FIG. 4 or FIG. 5 and the use of this B-stage agent, a mounting structure having an extremely high insulating property can be obtained.

[0030]

As is apparent from the above description, according to the present invention, a thin ribbon coil, which is formed by winding a plurality of thin ribbon conductive foils, is placed on an insulating portion of a printed circuit board with its end face facing downward. can do. Further, since it is not necessary to form a heat resistant insulating layer, it is possible to stabilize the height of the ribbon coil when it is attached to the printed board. Moreover, it is possible to save the labor of forming the heat-resistant insulating layer, improve the manufacturing efficiency, and reduce the cost.

Further, in the invention of claim 1, the insulating portion is made to project outward from the side surface of the ribbon coil or is made flush with the side surface, and the portion serves as a bridging portion of a conductive material and the power supply wiring layer and the ribbon. Since it is interposed between the side surface of the coil and the power supply wiring layer of the printed circuit board and the side surface of the thin ribbon coil are connected by a conductive material, that is, because it is a bridge connection with an insulating portion interposed, the conductive material is It does not wrap around the end face of the ribbon coil. Therefore, no electrical short circuit occurs. Further, in the invention of claim 2, since, so to speak, the bridge connection is made with an adhesive interposed, the conductive material does not wrap around to the end face of the ribbon coil. Therefore, like the invention of claim 1, no electrical short circuit occurs.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a mounting structure of the present invention in an enlarged manner.

FIG. 2 is an explanatory view showing a conductive connection method between a drive coil (thin band coil) and a power supply wiring layer in the embodiment of FIG.
(A) shows a state in which solder is attached to the connection surface, (B)
Shows the state that the solder has flowed down to the connection pads.

3A and 3B are views showing a coil unit formed by adopting the attachment structure of the present invention when attaching the thin ribbon coil to a printed circuit board, FIG. 3A being a plan view and FIG. 3B being a sectional view.

FIG. 4 is a partial sectional view showing a second embodiment of the present invention.

FIG. 5 is a partial sectional view showing a third embodiment of the present invention.

6A and 6B are views showing a fourth embodiment of the present invention, FIG. 6A is an enlarged partial sectional view and FIG. 6B is a plan view of the whole.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed circuit board (flexible wiring board) 12 Power supply wiring layer 13 Insulation part 13a Bridging part 21 Connection pad 22 Connection pad 31 Focus drive coil (thin strip coil 33) 32 Tracking drive coil (thin strip coil 33) 33 Thin strip Coil 34 Conductive material 35 Adhesive 40 Contact part

Claims (2)

[Claims] 1. A ribbon coil printed by placing at least one of the end faces of the ribbon coil on a printed circuit board and connecting a power supply wiring layer of the printed circuit board and a side surface of the ribbon coil with a conductive material. In a mounting structure to a substrate, the thin strip coil is placed in contact with an insulating portion of the printed circuit board, and at least a part of the insulating portion is projected outward from a side surface of the thin strip coil or a side surface thereof. A structure for mounting a thin coil on a printed circuit board, the same surface as that of, and a portion of the conductive coil serving as a bridging portion interposed between the power supply wiring layer and the side surface of the thin coil. 2. A ribbon coil printed by placing at least one of the end faces of the ribbon coil on a printed circuit board and connecting a power supply wiring layer of the printed circuit board and a side surface of the ribbon coil with a conductive material. In a mounting structure to a board, the ribbon coil is placed in contact with an insulating portion of the printed board, and a side surface of the ribbon coil and the insulating portion have a melting temperature higher than a melting temperature of the conductive material. Fixed with an adhesive,
A structure for attaching a thin coil to a printed circuit board, wherein the adhesive is interposed between the power supply wiring layer and a side surface of the thin coil as a bridging portion of the conductive material.