JPH10241953A - Transformer assembling method, transformer, and transformer mounting board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transformer assembling method by which the breakdown strength of a transformer can be increased and, at the same time, the performance of a ferrite core can be brought out sufficiently and the size and weight of the core can be reduced, the transformer, and a transformer mounting board. SOLUTION: In order to constitute a transformer of a winding section having a through hole section through which primary and secondary-side windings 3 are wound, a bobbin 2 integrally formed with primary- and secondary-side winding fixing sections which are continuously formed from the through hole section, and a magnetic core 1, the outer peripheral part of the winding 3 facing the mounting surface of a substrate and the primary- and secondary-side winding fixing sections of the bobbin 2 are stuck to the magnetic core 1 with a thermoplastic adhesive 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer assembling method, a transformer, and a transformer mounting board, and more particularly to a technique which can be particularly suitably applied to a transformer for a switching power supply using a ferrite core used in a power supply. It is.

[0002]

2. Description of the Related Art In general, a switching type power supply has advantages in that it can be made smaller and lighter than a dropper type power supply and has higher conversion efficiency. It is widely used for built-in power supplies and AC adapters.
As a result of the widespread use of the switching-type power supply device, various small and lightweight electronic devices can be easily carried by women and children, and their industrial contribution is highly evaluated.

Referring to the drawings, a transformer mounted on the substrate of such a switching type power supply device will be briefly described. FIG. 7 is a fragmentary sectional view of a conventional transformer 100 generally used. The varnish 108 covers the entire outer peripheral surface of the main body composed of the bobbin 102 wound with the coil 103 and the core 101 to obtain a finished product.

In the above configuration, each transformer 100 is configured to be comparatively flat, so that it can contribute to reduction in size and weight after being mounted on a board. However, such a reduction in size and weight has led to a new problem that when incorporated in a device, the device is exposed to an excessive impact load due to improper handling during transportation or the like.
Also, in the case of a power supply built into an AC adapter used on a desk, the power cord is hooked during use and the like, so that it can withstand an excessive impact load, assuming that it falls from the desk. There was a problem that required new countermeasures.

[0005] When the impact load acts as described above, the power supply device side includes various electronic components constituting the power supply device.
It has been found that excessive impact loads concentrate on relatively heavy transformers.

As shown in FIG. 8, the transformer is seriously damaged when an external force in the direction of arrow F acts on the mounting board K. That is, when an external force is applied, a moment in the direction of arrow M acts on the transformer 100. Then, the transformer 1
After being inserted into the mounting hole Ka of the substrate K by the lead pin P of 00, a sharp pulling force acts on the thin portion 102a on one side of the bobbin 102 fixed by the solder H in the pattern portion, resulting in the thin portion It is known that a breakage phenomenon of a transformer, which breaks from the wire 102a and breaks the lead wire 103, occurs.

Therefore, as a measure for preventing such breakage,
In order to improve the breaking strength of the bobbin 102, a thin portion 102a integrally formed from both sides of the bobbin wound portion of the coil 103
In this case, a reinforcement measure for providing a large C chamfer as shown in FIG. 7 is taken. Alternatively, JP-A-6-96
As disclosed in Japanese Unexamined Patent Publication No. 965-965 and Japanese Unexamined Patent Publication No. Hei 6-163278, there has been proposed a fixing method in which a transformer main body is housed in an outer case that holds the entire transformer and a gap is filled with a resin.

[0008]

However, according to the method of increasing the fracture resistance by providing the C chamfered portion in the thin portion 102a of the bobbin 102 as described above, the external dimensional accuracy of the ferrite core used is increased. Is large, so that a gap is formed between the core and the ferrite core, which makes it difficult to withstand an excessive impact load such as a drop.

If the bobbin 102 is made to have a sufficient thickness and a sufficient C-chamfered portion is formed in order to obtain a bobbin 102 having a sufficient strength, the effective window area as a transformer can be set large. Will disappear.
For this reason, there is a problem that the performance of the ferrite core incorporated in the bopin opening cannot be sufficiently brought out.

On the other hand, as disclosed in JP-A-7-300561, a method of using a resin having high mechanical strength for the bobbin material itself has been proposed. However, the usable materials for transformer bobbins must meet all safety standards of each country, such as UL standards, so that materials that meet all of them will be considerably more expensive than conventional materials. There's a problem. Also, from the viewpoint of actual use in the market, there is a problem that using a new material involves a great risk.

Further, as disclosed in the above-mentioned JP-A-6-96965 and JP-A-6-163278, a method of accommodating a transformer main body inside an outer case holding an entire transformer and fixing the same by resin filling is disclosed. According to this, not only is the cost increased, but also the transformer becomes large and heavy, and the advantages that the switching power supply device is small and lightweight cannot be fully utilized.

[0012] Accordingly, the present invention has been made in view of the above-mentioned problems, and it is possible to increase the fracture resistance, to sufficiently obtain the performance of a ferrite core, and to configure the ferrite core to be small and lightweight. And a transformer and a transformer mounting board.

[0013]

According to the present invention, there is provided a winding part having a through hole through which a primary side winding and a secondary side winding are performed. A transformer is formed from a bobbin integrally formed with a primary winding fixing part and a secondary winding fixing part continuously formed from the through hole, and a magnetic material core inserted into the through hole. In the transformer assembling method, the outer circumferential portion of the winding facing the substrate mounting surface and the magnetic material core, the primary winding fixing portion and the secondary winding fixing portion of the bobbin, And a bonding step of bonding between the magnetic material cores with a thermoplastic adhesive.

Further, the method is characterized by further comprising an impregnating step of impregnating an impregnating material containing varnish.

Further, a hot-melt adhesive containing a polypropylene resin is used as the thermoplastic adhesive.

Further, in the bonding step, a valley portion continuously formed between an outer peripheral portion of the winding and the magnetic material core, the primary winding fixing portion and the secondary winding fixing portion. The thermoplastic adhesive is applied to a surface portion continuously formed between the outer surface portion of the magnetic material core and the outer surface portion of the magnetic material core.

Also, in the bonding step, the outer peripheral portion of the winding, the magnetic material core, and the opposing surface portions of the primary winding fixing portion and the secondary winding fixing portion facing each other. The four corners formed at four corners, and the surface portion continuously formed between the outer surface portion of the primary winding fixing portion and the secondary winding fixing portion and the outer surface portion of the magnetic material core. hand,
It is characterized in that the thermoplastic adhesives are applied respectively.

Further, in the bonding step, a valley formed continuously between an outer peripheral portion of the winding and the magnetic material core, the primary winding fixing portion and the secondary winding fixing portion. Between the opposed facing surface portion and the outer peripheral portion of the winding, a portion continuous with the valley portion, outer surface portions of the primary winding fixing portion and the secondary winding fixing portion, and the magnetic material. For the surface part continuously formed between the outer surface part of the core,
It is characterized in that the thermoplastic adhesives are applied respectively.

Further, a winding portion having a through-hole portion through which a primary side winding and a secondary side winding are performed, a primary side winding fixing portion and a secondary side winding formed continuously from the through hole portion. In a transformer including a bobbin integrally formed with a fixed portion and a magnetic material core inserted into the through-hole portion, a portion between an outer peripheral portion of the winding facing the substrate mounting surface and the magnetic material core. When,
The magnetic core is bonded to the primary winding fixing part and the secondary winding fixing part of the bobbin with a thermoplastic adhesive.

Further, the present invention is characterized in that an impregnating material containing a varnish is further impregnated.

Further, a hot-melt adhesive containing a polypropylene resin is used as the thermoplastic adhesive.

Further, a valley continuously formed between the outer peripheral portion of the winding and the magnetic material core, and outer surface portions of the primary winding fixing portion and the secondary winding fixing portion. The present invention is characterized in that the thermoplastic adhesive is applied to a surface portion continuously formed with an outer surface portion of the magnetic material core.

Further, four corners formed between the outer peripheral portion of the winding, the magnetic material core, and opposing surfaces of the primary winding fixing portion and the secondary winding fixing portion. Four portions and a surface portion continuously formed between the outer surface portion of the primary winding fixing portion and the secondary winding fixing portion and the outer surface portion of the magnetic material core, It is characterized in that an adhesive is applied respectively.

Also, a valley formed continuously between the outer peripheral portion of the winding and the magnetic material core, and opposing surfaces of the primary winding fixing portion and the secondary winding fixing portion facing each other. A portion that is continuous with the valley between a portion and an outer peripheral portion of the winding; an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion; and an outer surface portion of the magnetic material core The thermoplastic adhesive is applied to each of the surface portions continuously formed between the above.

A winding portion having a through-hole for winding the primary side and the secondary side is provided, and a primary-side winding fixing portion continuously formed from both side openings of the through-hole. In a transformer mounting board on which a transformer composed of a bobbin integrally formed with a secondary winding fixing portion and a magnetic material core inserted into the through hole is mounted on a board mounting surface, Between the outer peripheral portion facing the substrate mounting surface and the magnetic material core, the primary winding fixing portion of the bobbin, and the
The transformer is characterized in that the transformer is provided in which a secondary winding fixing portion and the magnetic material core are bonded with a thermoplastic adhesive.

Further, in the transformer mounting board having the transformer mounted on the board mounting surface, the transformer is further impregnated with an impregnating material including a varnish.

Further, in the transformer mounting board having the transformer mounted on the board mounting surface, a hot melt adhesive containing a polypropylene resin is used as the thermoplastic adhesive.

Further, in a transformer mounting board having a transformer mounted on the board mounting surface, a valley formed continuously between an outer peripheral portion of the winding and the magnetic material core; And mounting the transformer coated with the thermoplastic adhesive on a surface portion continuously formed between an outer surface portion of the secondary winding fixing portion and an outer surface portion of the magnetic material core. It is characterized by.

Further, in the transformer mounting board having the transformer mounted on the board mounting surface, the outer peripheral portion of the winding, the magnetic material core, the primary side winding fixing section and the secondary side winding fixing section are formed. Four corners and four locations formed between opposed facing surface portions, and outer surface portions of the primary winding fixing portion and the secondary winding fixing portion and outer surface portions of the magnetic material core. The present invention is characterized in that the transformers each coated with the thermoplastic adhesive are mounted on a surface portion continuously formed therebetween.

Further, in a transformer mounting board having a transformer mounted on a board mounting surface, a valley formed continuously between an outer peripheral portion of the winding and the magnetic material core; And a portion continuous with the valley between an opposing surface portion of the secondary winding fixing portion and an outer peripheral portion of the winding; a primary winding fixing portion and the secondary winding fixing; The transformer coated with the thermoplastic adhesive is mounted on a surface portion continuously formed between an outer surface portion of the portion and an outer surface portion of the magnetic material core.

The mounting substrate is a power supply substrate for incorporating a device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below with reference to the accompanying drawings.

First, FIG. 1 shows a transformer 1 according to the first embodiment.
FIG. 2 is an external perspective view of the transformer 10 when viewed from the mounting surface side, and FIG. FIG. 3 is a sectional view taken along the line AA of FIG.

First, in FIG. 3, the bobbin is formed by injection resin from a predetermined resin material, and has a through-hole 2f having a through-hole 2t in which the primary and secondary windings 3 are formed. The primary-side winding fixing part and the secondary-side winding fixing part continuously formed from both side openings are integrally formed. The magnetic material core 1 is divided into two parts, and the transformer 10 is configured to surround the winding 3 by inserting the core part into the through hole 2t.

On the other hand, the printed circuit board K on which the transformer 10 is mounted has the pedestal portion 2k of the bobbin 2 of the transformer 10 directly in contact with the mounting surface, and the lead pins P serving as terminals of the transformer 10 are mounted on the mounting holes of the circuit board K. It is configured to be inserted into the portion Kb and then fixed with the solder H.

The outside of the winding 3 wound around the winding portion 2f of the bobbin 2 is covered with an insulating tape 7 as shown in the figure, and is covered with a varnish 8 impregnated entirely.

On the other hand, between the primary winding fixing part, the secondary winding fixing part, the upper surface of the magnetic material core 1 and the bottom surface of the magnetic material core 1 which are continuously formed from both side openings of the through hole 2t. Is formed in the gap. The gap between the core and the bobbin 2 on the surface facing the circuit board K is covered with the hot melt adhesive 15 in the gap. Tape 7
The hot melt adhesive 15 (for example, JET-MELT adhesive 3764 manufactured by Sumitomo 3M Ltd.)
Nos. 3748 and 3798) are applied.

In FIG. 1, the outer peripheral portion of the insulating tape 7 of the winding 3 of the transformer 10 and the surface portion 1b of the magnetic material core 1 are shown.
The hot melt adhesive 15 is also applied continuously to the valleys on both sides continuously formed between the hot melt adhesive 15 and the hot melt adhesive 15.

By bonding with the hot melt adhesive 15 in this manner, the fixed state between the bobbin 2 and the magnetic material core 1 can be strengthened. As a result, the transformer 10 is not affected by a drop impact regardless of the drop direction. Bobbin cracks can be prevented. In particular, the hot-melt adhesive 15 has an effect of absorbing the impact of a fall due to its softness, so that an appropriate shock absorber can be formed, which is very effective in preventing bobbin cracking.

The hot melt adhesive 15 cures at room temperature immediately after being discharged from the heat gun. Therefore, unlike the epoxy adhesive of a thermosetting resin, it does not require a long time for curing, and the workability is good, so that it is easy to handle and suitable for mass production.

Since the hot melt adhesive 15 has been used in a production process such as bonding and fixing of a housing in a conventional electronic device, there is no problem in safety.

Referring again to FIG. 3, the varnish 8 impregnates the entire transformer 10 in the impregnation step and cures. However, since the varnish 8 is mainly for preventing so-called transformer squeak, the adhesive strength is secured. It is not necessary if possible.

In FIG. 1, the bobbin 2 and the magnetic material 1
When there is almost no gap S between the outer surface 2a of the primary winding fixing portion and the secondary winding fixing portion and the outer surface 1a of the magnetic material core 1, hot surface is formed. By applying the melt adhesive 15 continuously, it is possible to restrict the movement of the magnetic material core 1 with respect to the bobbin 2 due to the fall, and to prevent the crack of the bobbin 2 due to the movement of the magnetic material core 1 of the transformer due to the fall. Become.

In the above configuration, as shown in the external perspective view of FIG. 2, the effect on the drop of the transformer 10 mounted on the circuit board K is effective in any of the XYZ drop directions. This is effective for falling in the Y direction. That is, since the movement of the magnetic material core 1 in the Y direction due to the impact of the transformer 10 falling in the Y direction can be regulated by applying the adhesive 15, the movement of the magnetic material core 1 causes the moment M applied to the pedestal portion 2k of the bobbin 2 to be reduced. The load can be alleviated, and the stress concentration on the ridge line at the boundary between the pedestal 2k of the transformer bobbin 2 and the side surface of the bobbin due to the rotational moment M of the magnetic material core 1 due to a drop impact can be dispersed, so that bobbin cracking can be prevented. become.

The hot melt adhesive 15 is an appropriate shock absorber because of its soft material. When a rotation moment M acts on the substrate K when the substrate K falls, a tensile load is applied to one pedestal 2k and the other pedestal 2k. However, these loads are alleviated by the hot melt 15 and do not cause unnecessary damage to the winding 3 of the transformer.
It is possible to prevent disconnection of the zero winding.

FIG. 4 shows a transformer 10 according to the second embodiment.
FIG. 1 is a perspective view of the outer appearance of a hot-melt adhesive 15 having the same components as those already described.
A surface portion continuously formed between the outer surface 2a of the primary winding fixing portion and the secondary winding fixing portion and the outer surface 1a of the magnetic material core 1; -1, 15-
2, 15-3 and 15-4 are partially applied.

With this configuration, it is possible to have a drop impact strength equivalent to that of the first embodiment with a smaller amount of the adhesive 15, and to mount other components close to the portion where the adhesive is not applied. Can be performed. Therefore, the degree of freedom in pattern design of the circuit board K is further improved. In addition, since the amount of hot melt used is small, it is suitable for mass production.

Next, FIG. 5 is an overall view of a transformer 10 according to a third embodiment.

In the figure, the same reference numerals are given to the components already described, and the description is omitted. When the hot melt adhesive 15 is applied to the circuit board K when the transformer 10 is mounted on the circuit board K, the hot melt adhesive 15 is opposed to the circuit mounting surface. It is applied to the entire area at the position covering the tangent line where the tape 7 of the bobbin on the surface side and the bobbin 2 are in contact.

With this configuration, the drop impact strength against cracks of the pedestal portion 2k of the transformer bobbin 2 can be further improved.

In the above-described embodiment, the transformer is provided with a magnetic material core disposed horizontally, but a transformer having a magnetic material core disposed vertically may be used.

FIG. 6 is a bottom view of the transformer of each of the above embodiments as viewed from the side facing the substrate mounting surface.
5A, a valley portion continuously formed between an insulating tape 7 which is an outer peripheral portion of a winding and a surface portion 1b of a magnetic material core 1, a primary winding fixing portion and a secondary winding fixing portion. 2 shows a state in which the hot melt adhesive 15 is applied to a surface portion continuously formed between the outer surface 2a of the magnetic material core 1 and the outer surface 1a of the magnetic material core 1.

In FIG. 6 (b), the insulating tape 7 which is the outer peripheral portion of the winding, the magnetic material core 1, and the opposing surface portions of the primary winding fixing portion and the secondary winding fixing portion which are opposed to each other. Between four corners 15-1, 15-2, 15-3 formed between
And hot melt adhesion to a surface portion continuously formed between the outer surface 2a of the primary winding fixing portion and the secondary winding fixing portion and the outer surface 1a of the magnetic material core 1. The state where each of the agents 15 is applied is shown.

In FIG. 6 (c), a valley formed continuously between the insulating tape 7 and the magnetic material core 1 which is an outer peripheral portion of the winding as shown in FIG. The hot melt adhesive 15 is applied so as to be continuous with the valley between the opposing surface of the secondary winding fixing portion and the outer peripheral portion of the winding. It is shown that the hot melt adhesive 15 is applied to a surface portion continuously formed between the outer surface of the secondary winding fixing portion and the outer surface of the magnetic material core.

With the above structure, the core and the bobbin can be more securely fixed to each other, so that the bobbin can be prevented from breaking due to the movement of the core of the transformer due to the impact of the fall, and the drop resistance of the transformer can be improved. In addition, the hot melt adhesive 15 has an effect of absorbing the impact of a drop since the material is soft.
In addition, since it cures quickly after application, the workability of application is good and easy to handle, and it is a material that has been used in conventional electronic device production processes and has no safety problems.
In addition, since the fixation in the area where the core 1 and the bobbin 2 are in contact with each other can be strengthened, the movement of the transformer due to the fall can be restricted, so that the bobbin can be prevented from cracking due to a drop impact, and the fall resistance of the transformer can be improved. In addition, since the fixing at the side surface area where the core and the bobbin are in contact can be strengthened, especially when a drop impact is applied in the lateral direction of the transformer, it is effective in regulating the movement of the transformer due to the fall, and the bobbin can be prevented from cracking due to the core movement, The transformer's drop resistance can be improved.

Further, the movement of the core of the transformer due to the drop impact can be restricted with a small amount of the adhesive. Also, by applying an adhesive to the four corners and four places on the back surface of the transformer core, components can be mounted close to the transformer, and the degree of freedom in pattern design of the circuit board is created.

The adhesion between the bobbin and the core can be further strengthened by the adhesiveness of the varnish, and the strengthening of the core and the bobbin by the application of a thermoplastic adhesive can be further reinforced, and the drop impact resistance can be improved.

As described above, by using a hot-melt adhesive to provide an appropriate shock absorber,
Breakage of the transformer winding can be prevented by reducing the drop impact and preventing unnecessary damage to the transformer winding. In addition, the drop strength of the transformer can be improved by adding a simple bonding step without largely changing the conventional transformer assembling step.

Further, as a measure against dropping in the transformer, application of the hot melt 15 may be performed after the varnish treatment step.

[0059]

As described above, according to the present invention, there is provided a transformer assembling method which can increase the fracture resistance, can sufficiently bring out the performance of a ferrite core, and can be made compact and lightweight. A transformer and a transformer mounting board can be provided.

[0060]

[Brief description of the drawings]

FIG. 1 is an external perspective view of a transformer 10 according to a first embodiment of the present invention as viewed from a mounting surface side of a circuit board.

FIG. 2 is an external perspective view illustrating a state in which a transformer 10 is mounted on a circuit board K.

FIG. 3 is a sectional view taken on line AA of FIG. 2;

FIG. 4 is an external perspective view of a transformer 10 according to a second embodiment as viewed from a mounting surface side of a circuit board K.

FIG. 5 is an external perspective view of a transformer 10 according to a third embodiment as viewed from a mounting surface side of a circuit board K.

FIG. 6 is a rear view of the transformer.

FIG. 7 is a front view of a transformer mounted on a circuit board of a conventional transformer and partially cut away.

FIG. 8 is a diagram illustrating the operation of a conventional transformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic material core 2 Bobbin 3 Winding 7 Insulating tape 8 Varnish 15 Hot melt adhesive (thermoplastic adhesive)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01F 31/00 A

Claims (19)

[Claims] 1. A winding part having a through hole through which primary and secondary windings are formed, a primary winding fixing part and a secondary winding continuously formed from the through hole. In a transformer assembling method for forming a transformer from a bobbin integrally formed with a fixed portion and a magnetic material core inserted into the through-hole portion, an outer peripheral portion of the winding facing a substrate mounting surface and the magnetic material The method further comprises a bonding step of bonding between the cores, and between the primary winding fixing portion and the secondary winding fixing portion of the bobbin and the magnetic material core with a thermoplastic adhesive. Transformer assembly method. 2. The transformer assembling method according to claim 1, further comprising an impregnating step of impregnating an impregnating material containing a varnish. 3. The transformer assembling method according to claim 1, wherein a hot-melt adhesive containing a polypropylene resin is used as the thermoplastic adhesive. 4. A valley formed continuously between an outer peripheral portion of the winding and the magnetic material core in the bonding step; a primary winding fixing portion and a secondary winding fixing portion. 4. The thermoplastic adhesive is applied to a surface portion continuously formed between the outer surface portion of the magnetic material core and the outer surface portion of the magnetic material core. 6. The transformer assembling method according to 1. 5. In the bonding step, between the outer peripheral portion of the winding, the magnetic material core, and opposing surface portions of the primary winding fixing portion and the secondary winding fixing portion facing each other. Four corners formed at four corners, and a surface portion continuously formed between an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion and an outer surface portion of the magnetic material core. The transformer assembling method according to any one of claims 1 to 3, wherein the thermoplastic adhesive is applied respectively. 6. In the bonding step, a valley formed continuously between an outer peripheral portion of the winding and the magnetic material core; and a primary winding fixing part and a secondary winding fixing part. A portion that is continuous with the valley between the opposed facing surface portion and the outer peripheral portion of the winding; an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion; and the magnetic material The transformer assembling method according to any one of claims 1 to 3, wherein the thermoplastic adhesive is applied to a surface portion continuously formed with an outer surface portion of the core. 7. A winding portion having a through-hole portion through which a primary side winding and a secondary side winding are performed, a primary side winding fixed portion and a secondary side winding continuously formed from the through hole portion. In a transformer including a bobbin integrally formed with a fixed portion and a magnetic material core inserted into the through hole, a portion between an outer peripheral portion of the winding facing the substrate mounting surface and the magnetic material core And a transformer, wherein the magnetic material core and the primary winding fixing portion and the secondary winding fixing portion of the bobbin are bonded to each other with a thermoplastic adhesive. 8. The transformer according to claim 7, further comprising an impregnating treatment with an impregnating material containing a varnish. 9. The transformer according to claim 7, wherein a hot-melt adhesive containing a polypropylene resin is used as the thermoplastic adhesive. 10. A valley continuously formed between an outer peripheral portion of the winding and the magnetic material core; and an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion. The transformer according to any one of claims 7 to 9, wherein the thermoplastic adhesive is applied to a surface portion continuously formed between the magnetic material core and an outer surface portion. 11. Four corners formed between the outer peripheral portion of the winding, the magnetic material core, and opposing surfaces of the primary winding fixing portion and the secondary winding fixing portion. Four portions, and a surface portion continuously formed between an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion and an outer surface portion of the magnetic material core. The transformer according to any one of claims 7 to 9, wherein an adhesive is applied respectively. 12. A valley continuously formed between an outer peripheral portion of the winding and the magnetic material core, and opposing surfaces of the primary winding fixing portion and the secondary winding fixing portion facing each other. A portion that is continuous with the valley between a portion and an outer peripheral portion of the winding; an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion; and an outer surface portion of the magnetic material core The transformer according to any one of claims 7 to 9, wherein the thermoplastic adhesive is applied to a surface portion continuously formed between the first and second portions. 13. A winding part having a through hole through which primary and secondary windings are formed, and a primary winding fixing part continuously formed from openings on both sides of the through hole. In a transformer mounting board on which a transformer composed of a bobbin integrally formed with a secondary winding fixing portion and a magnetic material core inserted into the through hole is mounted on a board mounting surface, Thermoplastic resin between the outer peripheral portion facing the substrate mounting surface and the magnetic material core, and between the primary winding fixing portion and the secondary winding fixing portion of the bobbin and the magnetic material core; A transformer mounting board comprising the transformer bonded by an adhesive. 14. The transformer mounting board according to claim 13, wherein an impregnation process of an impregnating material containing a varnish is further performed on the transformer. 15. The transformer mounting board according to claim 13, wherein a hot-melt adhesive containing a polypropylene resin is used as the thermoplastic adhesive. 16. A valley portion continuously formed between an outer peripheral portion of the winding and the magnetic material core, and an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion. 16. The transformer according to claim 13, wherein the transformers each coated with the thermoplastic adhesive are mounted on a surface portion continuously formed between the magnetic material core and an outer surface portion. The transformer mounting board according to the above. 17. Four corners formed between the outer peripheral portion of the winding, the magnetic material core, and opposing surface portions of the primary-side winding fixing portion and the secondary-side winding fixing portion. Four portions, and a surface portion continuously formed between an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion and an outer surface portion of the magnetic material core. 16. The transformer mounting board according to claim 13, wherein the transformers each having an adhesive applied thereto are mounted. 18. A valley continuously formed between an outer peripheral portion of the winding and the magnetic material core, and opposing surfaces of the primary winding fixing portion and the secondary winding fixing portion facing each other. A portion that is continuous with the valley between a portion and an outer peripheral portion of the winding; an outer surface portion of the primary winding fixing portion and the secondary winding fixing portion; and an outer surface portion of the magnetic material core The transformer mounting substrate according to any one of claims 13 to 15, wherein the transformers each coated with the thermoplastic adhesive are mounted on a surface portion continuously formed between the transformers. 19. The transformer mounting board according to claim 13, wherein the mounting board is a power supply board for incorporating a device.