JPH09223631A - Transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a transformer in which a creepage withstand voltage is enhanced between a primary coil and a secondary coil and in which the creepage withstand voltage is ensured easily by a method wherein insulating resin layers formed so as to be impregnated up to their inside are formed at respective winding end parts of the primary and secondary coils which are wound so as to be overlapped with each other via an insulating layer. SOLUTION: Insulating resin layers 2 formed so as to be impregnated up to their inside are formed at respective winding end parts of a primary coil 23 and a secondary coil 25 constituting a transformer 1 in a state that windings constituting the primary and secondary coils 23, 25 are wrapped. Then, when the insulating resin layers 2 are formed, an insulating resin is injected, by using a dispenser, into derivation grooves 29 formed on the bottom face of a bobbin 22 at the transformer 1 which is placed so as to be turned over upside down, the insulating resin which flows into through the derivation grooves 29 is soaked into gaps existing between the windings for the primary and secondary coils 23, 25 by making use of a capillary phenomenon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer, and more particularly to a transformer incorporated in a thin electronic device such as a mobile phone or an IC card for use.

[0002]

2. Description of the Related Art Conventionally, a transformer 21 of this type has an overall structure shown in FIG. 4, that is, a flat bobbin 22 made of an insulating resin, and an outer surface of the bobbin 22. The primary coil 23 wound around the secondary coil 25, the secondary coil 25 wound on the outer surface of the primary coil 23 via the insulating tape 24 which is an insulating layer, and the outer surface of the secondary coil 25 are covered. And an outer peripheral tape 26 wound to form an outer peripheral layer. A bobbin 22 constituting the transformer 21 has a through hole (not shown) formed along its longitudinal direction at the axial center position thereof.
A core 27 serving as a magnetic path is inserted in the through hole. At this time, a plurality of external terminals 28 projecting outward are provided at both ends along the longitudinal direction of the bobbin 22 in a state of being separated from each other. Pull-out groove 29 formed on the bottom surface of the
Terminal portions of the primary coil 23 and the secondary coil 25, which have been pulled out through the inside, are connected to each other.

By the way, in this transformer 21,
Primary coil 23 wound in layers with insulating tape 24
In order to improve and secure the creeping breakdown voltage between the secondary coil 25 and the secondary coil 25, as shown in FIG.
The insulating tape 24 is extended along the longitudinal direction of the primary and secondary coils 23 and 25, and the extended portions 24a located at both ends of the insulating tape 24 are respectively attached to the secondary coil 2.
The creepage distance between the primary coil 23 and the secondary coil 25 is lengthened by bending it to the 5 side and interposing it between the flange of the bobbin 22 and the winding end of the secondary coil 25. Is being done.

Alternatively, as another method for improving the creeping breakdown voltage, a thermosetting insulating resin is impregnated throughout the inside of the primary coil 23 and the secondary coil 25, or the primary and secondary coils 23 are used. , 25, a method of dipping an insulating resin on the whole, and a method of performing transfer molding are also adopted. When these methods are adopted, the outer peripheral tape 26 is generally not wound.

[0005]

However, in the method in which the extension portion 24a of the insulating tape 24 is interposed between the bobbin 22 and the secondary coil 25 which form the transformer 21, the work of bending the insulating tape 24 is not performed. Since it is difficult and time-consuming, it has been difficult to obtain good workability. Further, when such a method is adopted, dust and water are likely to enter through the extension portion 24a, so that there is a possibility that the breakdown voltage is deteriorated due to the surface contamination.

Further, impregnation and dipping of insulating resin,
When using methods such as transfer molding,
As a result, it is necessary to prepare expensive equipment suitable for these methods, resulting in a large increase in manufacturing cost. Then, when the insulating resin is thermally cured, the insulating resin, the bobbin 22, the primary and secondary coils 2
Since the coefficient of linear expansion differs from that of No. 3 and 25, the thermal stress caused by the difference in coefficient of linear expansion may cause disconnection of the primary and secondary coils 23 and 25. Furthermore, particularly in the case of resin dipping, the insulating resin may adhere to the outer surface of the external terminal 28 provided on the bobbin 22, so that the solderability at the time of mounting the transformer 21 deteriorates. There was also the inconvenience.

The present invention was devised in view of these inconveniences, and it is possible to easily improve and secure the creeping breakdown voltage between the primary coil and the secondary coil that are wound in a lap manner via an insulating layer. The purpose is to provide a transformer that can.

[0008]

A transformer according to claim 1 of the present invention comprises a primary coil and a secondary coil which are wound in a lap manner with an insulating layer interposed therebetween. In addition, an insulating resin layer formed by impregnating the inside of each of the winding ends of the secondary coil and the secondary coil is provided. The transformer according to claim 2 covers the primary coil wound on the bobbin through which the core is inserted, the secondary coil wound on the primary coil through the insulating layer, and the secondary coil. An outer peripheral layer formed by forming a lead groove into which a terminal portion of each of the primary coil and the secondary coil is inserted, the primary coil and the secondary coil being formed on the bottom surface of the bobbin. An insulating resin layer formed by impregnating the inside of each winding is formed at each winding end.

Further, the bottom surface of the lead-out groove formed in the bobbin constituting the transformer according to the third aspect of the present invention has an inclined shape that becomes deeper from the opening toward the winding end portion of the primary coil. ing. Furthermore, claim 4 of the present invention
The transformer according to 1 has a through hole for inserting a core.
2 wound on the primary coil through the secondary coil and the insulating layer
A secondary coil is provided, and the winding ends of the primary coil and the secondary coil are formed by impregnating the inside thereof and coating the outer surface thereof. An insulating resin layer is provided.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional perspective view showing a simplified overall structure of the transformer according to the present embodiment, and FIG. 2 is an enlarged sectional view showing the structure of a main part thereof. Reference numeral 1 in these drawings is a transformer. Is. The configuration of the transformer according to the present embodiment is basically the same as that of the transformer according to the conventional example. Therefore, in FIGS. 1 and 2, the same or corresponding parts and portions as those of FIG. 4 showing the conventional example have the same reference numerals. With
Detailed description here is omitted.

In the transformer 1 according to the present embodiment, like the conventional example shown in FIG. 4, a bobbin in which a core 27 formed by alternately stacking metal plates having an E-shape in plan view is inserted along the axial direction. 22, a primary coil 23 wound on the outer surface of the bobbin 22, and a secondary coil 25 wound on the outer surface of the primary coil 23 via an insulating tape 24 functioning as an insulating layer. The outer peripheral tape 26 is wound around the outer surface of the secondary coil 25 to form an outer peripheral layer, and the bottom surface of the bobbin 22 includes the primary coil 23 and the secondary coil 25. The lead-out grooves 29 through which the terminal portions are inserted are formed apart from each other. A plurality of external terminals 28 are provided on both end surfaces of the bobbin 22 along the longitudinal direction so as to project, and the primary coil 23 and the secondary coil 25 that have been pulled out by being inserted through the pull-out groove 29. Each terminal portion is connected to each of the corresponding external terminals 28.

Further, at the winding end portions of the primary coil 23 and the secondary coil 25 constituting the transformer 1, an insulating resin layer 2 formed by impregnating the inside thereof is formed. It is provided in a state in which the windings constituting 23 and 25 are wrapped. When forming these insulating resin layers 2, the lead-out groove 29 formed on the bottom surface of the bobbin 22 of the transformer 1 placed upside down.
The insulating resin is injected into the inside by a dispenser having a well-known structure, and the insulating resin flowing through the drawing groove 29 is present in the gap between the windings of the primary and secondary coils 23 and 25 (not shown). It is made to infiltrate by utilizing the capillary phenomenon in the inside.

That is, in this case, for example, 1
The required amount of insulating resin is poured through the lead-out groove 29 formed on one side of the winding ends of the secondary and secondary coils 23 and 25, and the required amount is passed through the lead-out groove 29 formed on the other side. After pouring a certain amount of insulating resin,
The insulating resin layer 2 is formed again by pouring the insulating resin from the pull-out groove 29 on the one side. Of course, it is not limited to such a procedure,
When the above procedure is adopted, there is an advantage that the insulating resin layer 2 in which the insulating resin is impregnated in a more uniform state can be easily formed. The bottom surface of the extraction groove 29, which is also used for pouring the insulating resin, becomes deeper from the opening toward the winding end portion of the primary coil 23, as shown in an enlarged view in the sectional view of FIG. It is preferable to have an inclined shape in advance, and in the case of having such an inclined shape, the insulating resin will easily flow.

Further, the primary and secondary coils 2 here
The insulating resin layer 2 at the winding ends of the windings 3, 25 is
It is formed by using an insulating resin such as an adhesive or a varnish having a thermosetting epoxy type or a silicone type, but is not limited to these resins,
Other insulating resins can be used as long as they have low viscosity. Although the insulating resin has thermosetting properties as in the conventional example, in the present embodiment, the insulating resin layer is provided only at the winding end portions of the primary and secondary coils 23 and 25, respectively. Since 2 is not provided, the inconvenience of the conventional example in which the insulating resin is impregnated throughout the primary and secondary coils 23 and 25 does not occur.

Further, in the bobbin 22 constituting the transformer 1 at this time, although not shown in the drawing, the
The inner surface of the collar portion 22a in which the winding ends of the secondary and secondary coils 23 and 25 are arranged close to each other extends from the primary coil 23 side toward the secondary coil 25 side, that is, from the inside to the outside. It may be inclined as described above, and if this is done, the advantage that the winding ends of both the primary and secondary coils 23 and 25 are easily impregnated with the insulating resin is also obtained.

By the way, although the transformer 1 in this embodiment is provided with the bobbin 22, there is also the transformer 11 not having the bobbin 22 as shown in FIG.
Therefore, the configuration when the present invention is applied to the transformer 11 according to the modified example that does not include the bobbin 22 will be described based on FIG. In FIG. 3, the same parts and portions as those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

The transformer 11 according to this modification has a core 2
7, a primary coil 12 having a through hole (not shown) for inserting the core 27 formed along the axial direction, and an insulating tape 24, and the primary coil 12 is wound on the outer surface of the primary coil 12. The secondary coil 13 and the outer peripheral tape 26 wound on the outer surface of the secondary coil 13 are provided.
Base plate 1 having insulating properties at both ends along the longitudinal direction of 7
4 are attached in a fixed state. Then, the electrode portions 15 are provided at positions separated from each other on the outer end surface of each pedestal plate 14, and the terminal portions of the primary coil 12 and the secondary coil 13 are soldered to the electrode portions 15, respectively. Connected by.

At this time, the winding ends of the primary coil 12 and the secondary coil 13 each have an insulating resin layer 16 formed by impregnating the inside and covering the outer surface thereof. It is provided. Each of these insulating resin layers 16 uses the above-mentioned insulating resin, that is, an insulating resin such as a thermosetting epoxy-based or silicon-based adhesive or varnish, and is exposed to the outside. The winding ends of the primary and secondary coils 12 and 13 are applied by brush coating or the like. Therefore, the applied insulating resin is used for the primary and secondary coils 1
At the same time as it soaks into the gap (not shown) existing between the windings 2 and 13 by the capillary phenomenon, it adheres along the outer surface of the winding ends of the primary and secondary coils 12 and 13. Therefore, the insulating resin layer 16 is provided on the winding ends of the primary coil 12 and the secondary coil 13.

That is, as described above, when the transformer according to the present invention is the transformer 1 including the bobbin 22 as shown in FIG. 1, the transformer 11 as shown in FIG. However, the transformer is configured to include the primary and secondary coils 23 and 25 (12, 13) that are wound in a layered manner through an insulating layer such as the insulating tape 24. And secondary coils 23, 25
An insulating resin layer 2 (16) formed by impregnating at least the inside of each of the winding ends (12, 13)
Is provided.

[0021]

As described above, according to the transformer of the present invention, the transformers that are wound around each other through the insulating layer are
The winding ends of the secondary coil and the secondary coil are each provided with an insulating resin layer impregnated therein, so that it is not necessary to bend the insulating layer to the secondary coil side. The creepage distance between the primary and secondary coils increases. Therefore, the creeping breakdown voltage between the primary coil and the secondary coil is improved, and the improved creeping breakdown voltage can be easily ensured. At this time, since the insulating layer is not bent to the side of the secondary coil, not only the difficult work of bending the insulating layer is unnecessary, but also the bent insulating layer is exposed to the outside. There will be no creeping pollution associated with.

Further, unlike the conventional example in which the entire insides of the primary coil and the secondary coil are impregnated with an insulating resin, the insulating resin layer is provided only at the winding end portions of the primary and secondary coils. Since they are not provided, these insulating resin layers can be formed by brush coating or dropping with a dispenser, and as a result, there is no need to use expensive equipment, and there is a risk of disconnection of the primary and secondary coils. Not only disappearing,
It is possible to obtain the relative effect of not lowering the solderability when mounting the transformer.

[Brief description of drawings]

FIG. 1 is a sectional perspective view showing a simplified overall structure of a transformer according to an embodiment.

FIG. 2 is an enlarged cross-sectional view showing a main part structure of a transformer according to the present embodiment.

FIG. 3 is a sectional perspective view showing a simplified overall structure of a transformer according to a modification.

FIG. 4 is a cross-sectional perspective view showing a simplified overall structure of a transformer according to a conventional example.

FIG. 5 is an enlarged cross-sectional view showing a main part structure of a transformer according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 transformer 2 insulating resin layer 11 transformer 12 primary coil 13 secondary coil 16 insulating resin layer 23 primary coil 24 insulating tape (insulating layer) 25 secondary coil

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoshitaka Yamashita Yoshitaka Yamashita 2-26-10 Tenjin Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd.

Claims (4)

[Claims] 1. A transformer comprising a primary coil and a secondary coil that are wound one over another via an insulating layer, wherein the winding ends of the primary coil and the secondary coil are A transformer having an insulating resin layer formed by impregnating the interior thereof. 2. A primary coil wound on a bobbin through which a core is inserted, a secondary coil wound on the primary coil via an insulating layer, and an outer circumference formed by covering the secondary coil. The bobbin has a primary coil and two
A transformer in which lead-out grooves through which the end portions of the respective secondary coils are inserted is formed, and the winding ends of the primary coil and the secondary coil each have an insulating resin layer impregnated therein. A transformer characterized by being formed. 3. The transformer according to claim 2, wherein the bottom surface of the lead-out groove formed on the bobbin has an inclined shape that becomes deeper from the opening toward the winding end portion of the primary coil. A transformer characterized by that. 4. A transformer comprising a primary coil having a through hole for inserting a core and a secondary coil wound on the primary coil with an insulating layer interposed therebetween. A transformer, characterized in that an insulating resin layer is formed on each winding end of each of the secondary coil and the secondary coil so as to be impregnated to the inside thereof and to cover the outer surface thereof.