JPH10229025A - Transformer assembling method, transformer, and transformer-mounting circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transformer assembling method by which a transformer can be constituted, so that the rapture strength of the transformer may be enhanced, the performance of a ferrite core many be brought out sufficiently, and the size and weight of the transformer may be reduced, and a transformer and a transformer mounting circuit board. SOLUTION: In order to constitute a transformer 10 of a bobbin 2, on which a winding section having a through-hole section for winding primary- and secondary-side windings 3 and primary- and secondary-side winding fixing sections are continuously formed from openings on both sides of the through-hole section, is integrally formed and a magnetic core 1 which is inserted into the through-hole section is provided, so as to surround the windings 3. Both or one of the primary- and secondary-side winding fixing sections is stuck to the magnetic core 1 with a thermosetting adhesive 4.

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 circuit board mounted with a transformer, 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. Things.

[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 a substrate of such a switching type power supply device will be briefly described. FIGS. 10 and 11 show the appearance of a transformer 100 generally used conventionally. FIG. 10 is a perspective view in which a transformer and a core are fixed by an adhesive, and FIG. 11 is a type in which the transformer and the core are fixed by varnish impregnation. And FIG.
In the above, after the coil 103 is wound around the bobbin 102 and the core 101 is inserted into the opening of the bobbin 102, the parts shown in the drawing are fixed by the adhesives 105 and 106 to obtain a finished product. . In FIG. 11, the varnish 108 is coated on the entire outer peripheral surface 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. 12, 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. At this time, the thin portion 1 on one side of the bobbin 102, which is fixed to the pattern portion of the substrate K by soldering with the lead pins P of the transformer 100,
It is known that as a result of a sudden pulling force acting on the thin portion 102a, the transformer breaks from the thin portion 102a.

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 C, chamfering is performed to take reinforcement measures.

[0008] Alternatively, as disclosed in JP-A-6-96965 and JP-A-6-163278, the transformer body is housed in an outer case that holds the entire transformer, and the gap is filled with resin. Fixing methods have been proposed.

[0009]

However, as described above, the C-chamfered portion is provided in the thin portion 102a of the bobbin 102. According to the method of increasing the fracture resistance, the outer dimensions of the ferrite core used vary widely, so that a gap is formed between the ferrite core and the endurance of the ferrite core. There is a problem that it becomes difficult.

Further, if the bobbin 102 is made to have a sufficient strength and the entire wall thickness is made large so as to form a sufficient C chamfered portion, the effective window area as a transformer can be set large. Will disappear.
For this reason, there is a problem that even the performance of the ferrite core built in the bobbin opening cannot be sufficiently brought out.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. Hei 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. In addition, 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.

[0013] 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 extract the performance of a ferrite core, and to reduce the size and weight of the ferrite core. The purpose of the present invention is to provide a transformer assembling method, a transformer and a circuit board mounted with a transformer. More specifically, it is an object of the present invention to provide a transformer that can be manufactured in a current transformer manufacturing process without using special components and materials and that has a fall countermeasure.

[0014]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, according to the present invention, a winding portion having a through-hole portion in which a primary winding and a secondary winding are wound, and a continuous winding portion from both side openings of the through-hole portion A transformer is constituted by a bobbin integrally formed with a primary winding fixing portion and a secondary winding fixing portion to be formed, and a magnetic material core inserted into the through-hole portion and provided so as to surround the winding. The method for assembling a transformer includes a bonding step of bonding and / or fixing between the magnetic material core and both or any of the primary winding fixing part and the secondary winding fixing part with a thermosetting adhesive. .

[0015] Further, a winding portion having a through-hole for winding the primary winding and the secondary winding, and a primary winding continuously formed from openings on both sides of the through-hole. In the transformer, comprising: a bobbin integrally formed with a fixing portion and a secondary winding fixing portion; and a magnetic material core inserted into the through-hole portion and provided to surround the winding, It is characterized in that both or any of the wire fixing portion and the secondary winding fixing portion and the magnetic material core are bonded and fixed with a thermosetting adhesive.

A winding portion having a through hole through which the primary winding and the secondary winding are wound, and a primary winding continuously formed from openings on both sides of the through hole. A transformer having a transformer formed on a substrate, the transformer comprising a bobbin integrally formed with a fixed portion and a secondary winding fixed portion, and a magnetic material core inserted into the through hole and provided to surround the winding. The mounting circuit board is characterized in that both or either of the primary winding fixing part and the secondary winding fixing part and the magnetic material core are bonded and fixed with a thermosetting adhesive.

[0017]

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

FIG. 1 is a plan view showing the structure of a first embodiment of a transformer, and FIG. 2 is a front view of FIG. 1 and 2, a transformer used for a switching power supply device includes a core 1 made of ferrite, as shown in FIG.
A bobbin 2 made of resin for winding a winding, a winding, an interlayer insulating tape, and a barrier tape for securing a primary-secondary distance required for obtaining safety standards were used. Winding part 3 which is a coil wound by a predetermined winding method
It is composed of

As shown in FIGS. 1 and 2, an adhesive 4 serving as an adhesive means for fixing the bobbin 2 and the core 1 is connected to the primary winding side and the secondary winding side of the flange 2a of the bobbin 2. A total of four portions are applied on both side portions on the line side.
As the adhesive 4, an epoxy adhesive which is a thermosetting adhesive is used. On the other hand, the adhesive 5 is used at a joint portion to fix the cores 1 to each other. The adhesive 6 is used between the core 1 and the upper end 2 b on the secondary side of the bobbin 2.

The transformer 10 reinforced by using the adhesives 4, 5, and 6 as described above is mounted on a substrate, and various drop tests are performed. A comparison is made between the transformer 1 having the core 1 and the bobbin 2 not fixed. A drop experiment was performed. At this time, in the conventional transformer 100, it was expected that the core 1 and the bobbin 2 would not be fixed at a portion corresponding to the edge, and thus the core 1 might be cracked. The result is shown in FIG. As a result, cracks occurred in the thin portion 102a. From this, the moment M and excessive impact are concentrated on the relatively heavy transformer in the direction shown by the arrow in FIG.
It was confirmed that it could not withstand the moment and the impact, and it was relatively easy to break from the vicinity of the lead portion of the winding portion. From the above, it was found that the core 1 had sufficient impact resistance and the strength of the bobbin 2 was insufficient.

Therefore, as a countermeasure, as shown in FIG. 10, an epoxy-based adhesive fixed by only one adhesive 106 as shown in FIG. 10 is replaced with an epoxy-based adhesive as shown in FIG. 1 and FIG. The bobbin 2 and the core 1 are fixed by applying the adhesive 4 at the flange portions 2a on both sides of the secondary winding, thereby increasing the bonding strength between the bobbin 2 and the core 1 and providing a moment when falling. The rupture force applied to the bobbin 2, such as M and impact load, was configured to be dispersed.

The transformer 10 having the above configuration is placed on a desk (about 7
5cm) when dropped on the floor, in the same direction, 7
It was confirmed that a material that did not break even if dropped repeatedly was obtained.

Therefore, according to the above configuration, it is possible to cope with the simple change of simply increasing the number of locations where the adhesive 4 of the predetermined bonding portion of the flange portion 2a is used in the adhesive application process of the transformer manufacturing process. There is an advantage that it can be manufactured without using special means or materials.

Further, since the epoxy adhesive, which is an adhesive means for fixing the bobbin 2 and the core 1, is a thermosetting adhesive, it is heated by self-heating when the transformer is operated in the power supply device. Since natural curing is promoted and thermal conductivity is good, there is an advantage that adhesive strength is not weakened as compared with thermoplastics. [Second Embodiment] In the plan view showing the structure of the second embodiment of the transformer in FIG. 3 and the front view in FIG. In the first embodiment, the different configuration will be described.
The application position of the adhesive 4 for fixing the core 1 to the core 1 is 1
A collar portion 2a on both sides of the secondary winding side and the secondary winding side,
It was located on the surface facing the bobbin 2 facing the core 1 and at least including the four corners of the bobbin 2.

In the second embodiment, as shown in FIG. 3 and FIG. 4, the application positions of the adhesive 4 for fixing the bobbin 2 and the core 1 are different between the primary winding side and the secondary winding side. Side surfaces 2c on both sides of the side of the transformer, on a tangent to the bobbin facing the core on the outer periphery of the transformer, and at a position including at least four corners of the bobbin 2. And adhesives 5, 6
Is applied in the same manner as in the first embodiment.

The transformer 10 having the above configuration is placed on a desk (about 7
5cm) when dropped on the floor, in the same direction, 7
It was confirmed that a material that did not break even if dropped repeatedly was obtained.
In addition, since it is possible to cope with the simple change of simply increasing the adhesive 4 at a predetermined bonding portion of the side surface portion 2c in the adhesive application step of the transformer manufacturing process, it can be manufactured without using special means or materials. There is. [Third Embodiment] FIG. 5 is an external perspective view of the structure of the third embodiment viewed from the bottom side of a transformer 10, and FIG.
FIG. 6 is a front view of the transformer 10 of FIG. 5 in a board mounting direction.

In FIGS. 5 and 6, the components already described are given the same reference numerals and the description thereof will be omitted. The characteristic parts will be described. Is the same as

A different configuration is that an application position of the adhesive 4 for fixing the bobbin 2 and the core 1 is a portion where the opposing surface 2 d on the primary winding side and the secondary winding side intersects with the bottom surface of the core 1. And at least on the tangent line where the bobbin at the four inner corners of the transformer and the core are in contact, as viewed from the surface of the transformer facing the substrate.

Normally, since there is a dimensional play between the core and the bobbin, in the present embodiment, when the core is assembled to the bobbin and turned over when the adhesive 4 is applied, the weight of the core 1 is
A slight gap is created between the bobbin and the core.

The bobbin 2 and the core 1 are located in the gap.
Is applied, ie, 1
At least on both sides of the secondary winding side and the secondary winding side, at least on the tangent line where the bobbin at the four inner corners of the transformer and the core come into contact when viewed from the surface facing the substrate of the transformer.

Therefore, since the adhesive 4 can be applied to this position, a sufficient amount of the adhesive 4 can be applied as compared with the above-described embodiments, and the gap between the core 1 and the bobbin 2 can be increased. In addition, since a part of the adhesive 4 goes around, there is an advantage that sufficient adhesive strength can be provided. [Fourth Embodiment] FIG. 7 is an external perspective view showing the structure of a transformer according to a fourth embodiment viewed from the lower surface of the transformer.
FIG. 8 is a front view showing the structure of the transformer of FIG. 7 in the mounting direction.

In both figures, the same components as those already described are denoted by the same reference numerals, and description thereof will be omitted. Different components will be described. When the core 1 is fixed to the bobbin 2, it is moved to one side. 7 and 8, the positions of the bonding means 4 for fixing the bobbin 2 and the core 1 are different on both sides of the primary winding side and the secondary winding side of the bonding means. One is on a surface facing the bobbin opposite to the core and includes at least two corner portions of the bobbin of the transformer, and the other is at least a substrate of the transformer. When viewed from the surface opposite to the above, the bobbin and the core at two inner corners on the winding side where the outer peripheral side is not stopped at the four inner corners of the transformer are on a tangent line where the bobbin and the core are in contact. This is a compromise where the primary winding side and the secondary winding side are set to the bonding positions of the first and third embodiments.

This embodiment provides a more effective means when there is a bias in the moment of destruction due to the impact of a drop.

Further, in FIGS. 7 and 8, when the core is fixed to the bobbin, the bonding means is located on a surface opposed to the core and in contact with the bobbin and at least a position including two corner portions of the bobbin of the transformer. Since the core is fixed to one side so that the area can be increased, there is an advantage that the reinforcement of the adhesive in this portion is further strengthened. [Fifth Embodiment] FIG. 9 is a front view of a transformer showing the structure of the fifth embodiment of the transformer. The feature of this embodiment is that in any of the above embodiments, the varnish 8 is impregnated after being bonded with the adhesive 4 for fixing the bobbin and the core, and the varnish 8 is dried. Since the temperature at this time is set at about 120 ° C., the thermosetting adhesive can be kept in a cured state, which is convenient.

With this configuration, the transformer squeak due to a natural frequency which is likely to occur when only the adhesives 4, 5, and 6 are fixed is eliminated, and the varnish penetrates into the gap between the core and the bobbin. By doing so, there is an advantage that the surface is bonded and the drop strength is further improved.

As described above, in a transformer in which a magnetic material core is attached to a winding portion in which a bobbin of a transformer is wound, a bobbin is provided on each side of a primary winding side and a secondary winding side. And an adhesive means for fixing the core and
Since the bonding means for fixing the bobbin and the core is a thermosetting adhesive, it can be formed in the current transformer manufacturing process without using any special means or materials, and the drop strength is maintained. You can get a transformer.

The bonding means for bonding the bobbin and the core on both sides of the primary winding side and the secondary winding side are fixed at a plurality of positions, and the bobbin is opposed to the core. A position including at least the four corners of the bobbin of the transformer, or a position tangent to the bobbin facing the core on the outer periphery of the transformer and including at least the four corners of the bobbin of the transformer; Therefore, in addition to the above effects, in the transformer manufacturing process,
Since the transformer does not need to be turned over, it is easy to apply the adhesive, and it is easy to respond to in-line automation.

The bonding means for bonding the bobbin and the core on both sides of the primary winding side and the secondary winding side are fixed at a plurality of positions, at least facing the transformer substrate. From the point of view, since the bobbin and the core at the four inner corners of the transformer are on the tangent line where the core touches, more adhesive can be attached, and the adhesive can be easily inserted into the gap between the core and the bobbin. Therefore, a stronger and more stable adhesive strength can be obtained.

In the bonding means for fixing the bobbin and the core, at different bonding positions on both sides of the primary winding and the secondary winding, one of the surfaces is in contact with the core and in contact with the bobbin. Above and at least two of the transformer bobbins
Or at a position including two corner portions of the bobbin of the transformer, and at least at a position including the two corner portions of the bobbin of the transformer. When viewed from the surface facing the substrate, the bobbin due to the impact at the time of falling because the bobbin and the core are on the tangent line where the bobbin and the core are in contact at the two inner corners of the winding side where the outer peripheral side is not stopped at the four inner corners of the transformer When there is a bias in the breaking moment, there is an advantage that more effective reinforcement can be performed.

Further, when the core is fixed to the bobbin, the area of the bonding means on the surface facing the core and in contact with the bobbin, and at least the position including the two corners of the bobbin of the transformer can be increased. In addition, since the core is fixed to one side, the area of the bonding portion can be increased, and the bonding strength can be further increased.

After the bobbin and the core are bonded by the bonding means for fixing, the varnish is impregnated with the varnish so that the transformer squeaks due to the natural frequency which is likely to occur when only the adhesive is fixed. The varnish disappears, and the varnish penetrates into the gap between the core and the bobbin, so that the varnish adheres to the surface and the drop strength is further improved.

[0042]

As described above, according to the present invention,
It is possible to provide a transformer assembling method, a transformer, and a transformer-mounted circuit board that can increase the breakdown resistance and can sufficiently bring out the performance of a ferrite core, and can be configured to be small and lightweight.
Specifically, it is possible to provide a transformer that can be manufactured in a current transformer manufacturing process without using special components and materials and that has a countermeasure against falling.

[0043]

[Brief description of the drawings]

FIG. 1 is a plan view showing the structure of a first embodiment of a transformer.

FIG. 2 is a front view of FIG.

FIG. 3 is a plan view showing a structure of a second embodiment of a transformer.

FIG. 4 is a front view of FIG. 3;

FIG. 5 is an external perspective view showing a structure of a third embodiment of a transformer as viewed from a lower surface side.

FIG. 6 is a front view of the transformer of FIG. 5 in a mounting direction.

FIG. 7 is an external perspective view showing a structure of a transformer according to a fourth embodiment as viewed from a lower surface side.

8 is a front view of the transformer of FIG. 7 in a mounting direction.

FIG. 9 is a front view of a transformer showing a structure of a fifth embodiment.

FIG. 10 is an external perspective view showing the external shape of a conventional transformer in which a core and a bobbin are fixed with an adhesive.

FIG. 11 is an external perspective view showing an outer shape of a transformer in a conventional example in which a core and a bobbin are fixed by varnish impregnation.

FIG. 12 is a front view showing a transformer breakdown phenomenon after a drop test according to a conventional method.

FIG. 13 is a front view showing a conventional example for improving the breaking strength of a bobbin.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core 2 Bobbin 3 Coil (winding part) 4 Adhesive 5 Adhesive 6 Adhesive 8 Varnish K Board P Lead pin

Claims (19)

[Claims] 1. A winding part having a through-hole for winding a primary winding and a secondary winding, and a primary winding continuously formed from openings on both sides of the through-hole. In a transformer assembling method, a transformer includes a bobbin integrally formed with a fixed part and a secondary winding fixed part, and a magnetic material core inserted into the through hole and provided so as to surround the winding. A transformer assembling method, comprising a bonding step of bonding and / or fixing between and / or any of the secondary winding fixing part and the secondary winding fixing part and the magnetic material core with a thermosetting adhesive. 2. The bonding step, wherein the magnetic material parallel to a portion including a flange portion of the primary winding fixing portion and the secondary winding fixing portion, and the both side openings of the through hole portion. 2. The transformer assembling method according to claim 1, wherein a plurality of portions between the both side portions of the core are bonded and fixed by the thermosetting adhesive. 3. The bonding step includes: a side portion of the primary winding fixing portion and the secondary winding fixing portion along a longitudinal direction of the through-hole portion; and a longitudinal direction of the through-hole portion. 2. The transformer assembling method according to claim 1, wherein a plurality of portions between both side portions of the magnetic material core are bonded and fixed by the thermosetting adhesive. 4. The bonding step includes the steps of: mounting an inner portion of the primary winding fixing portion and an inner portion of the secondary winding fixing portion facing each other; and a bottom portion of the magnetic material core facing the substrate after mounting the substrate. The transformer assembling method according to claim 1, wherein the plurality of portions are fixed by the thermosetting adhesive. 5. The thermosetting adhesive between the inside portion of the secondary winding fixing portion and the bottom portion of the magnetic core facing the substrate after the substrate is mounted. 2. The transformer assembling method according to claim 1, wherein the magnetic material core is moved to the secondary side or the primary-side winding fixing portion side for the adhesive fixation, and then the adhesive fixation is performed. 6. The transformer assembling method according to claim 1, wherein the bonding step further includes a step of performing a varnish-containing impregnation process after the bonding and fixing. 7. A winding part having a through-hole for winding a primary winding and a secondary winding, and a primary winding continuously formed from openings on both sides of the through-hole. A transformer comprising: a bobbin integrally formed with a fixing portion and a secondary winding fixing portion; and a magnetic material core inserted into the through-hole portion and provided to surround the winding. A transformer, wherein at least one or both of a wire fixing part and the secondary winding fixing part and the magnetic material core are bonded and fixed with a thermosetting adhesive. 8. A portion including flange portions of the primary winding fixing portion and the secondary winding fixing portion, and both side portions of the magnetic material core parallel to the both side openings of the through hole. The transformer according to claim 7, wherein the thermosetting adhesive is used for bonding and fixing at a plurality of locations between the transformer and the thermosetting adhesive. 9. A side surface portion of the primary winding fixing portion and the secondary winding fixing portion along a longitudinal direction of the through hole portion, and a side surface portion of the magnetic material core along a longitudinal direction of the through hole portion. 8. The transformer according to claim 7, wherein a plurality of portions between the both side portions are bonded and fixed by the thermosetting adhesive. 10. A plurality of magnetic heads between an inner portion facing the primary winding fixing portion and the secondary winding fixing portion and a bottom surface portion of the magnetic material core facing the substrate after mounting the substrate. The transformer according to claim 7, wherein the portion is fixed by the thermosetting adhesive. 11. An inner part of the secondary winding fixing part,
After the substrate is mounted, the magnetic material core is bonded to the secondary side or the first side in order to adhere and fix with the thermosetting adhesive between the magnetic material core and the bottom surface portion of the magnetic material core facing the substrate.
The transformer according to claim 7, wherein the adhesive is fixed after moving to a secondary winding fixing portion side. 12. The transformer according to claim 7, wherein a varnish-containing impregnation treatment is performed after the bonding and fixing. 13. A winding part having a through-hole for winding a primary winding and a secondary winding, and a primary winding continuously formed from openings on both sides of the through-hole. A transformer having a transformer formed on a substrate, the transformer comprising a bobbin integrally formed with a fixed portion and a secondary winding fixed portion, and a magnetic material core inserted into the through hole and provided to surround the winding. In the mounted circuit board, a transformer mounting circuit characterized in that a thermosetting adhesive is used to fix and / or fix the magnetic material core to at least one of the primary winding fixing portion and the secondary winding fixing portion. substrate. 14. A portion including flange portions of said primary winding fixing portion and said secondary winding fixing portion, and both side portions of said magnetic material core parallel to said both side openings of said through hole portion. 14. The transformer-mounted circuit board according to claim 13, wherein the thermosetting adhesive is used to bond and fix a plurality of portions between the two portions. 15. The 1 along the longitudinal direction of the through hole portion.
In a plurality of portions between side portions of the secondary winding fixing portion and the secondary winding fixing portion and both side portions of the magnetic material core along a longitudinal direction of the through-hole portion, the thermosetting type is provided. 14. The transformer-mounted circuit board according to claim 13, wherein the transformer-mounted circuit board is bonded and fixed with an adhesive. 16. A method according to claim 16, wherein a portion between the inner side of the primary winding fixing portion and the side of the secondary winding fixing portion facing each other, and a bottom surface portion of the magnetic material core facing the substrate after being mounted on the substrate. The transformer-mounted circuit board according to claim 13, wherein a plurality of portions are bonded and fixed in advance with the thermosetting adhesive. 17. An inner part of the secondary winding fixing part,
After the substrate is mounted, the magnetic material core is bonded to the secondary side or the first side in order to adhere and fix with the thermosetting adhesive between the magnetic material core and the bottom surface portion of the magnetic material core facing the substrate.
14. The transformer-mounted circuit board according to claim 13, wherein the adhesive is fixed after moving to a secondary winding fixing portion side. 18. The method according to claim 13, wherein an impregnation process including a varnish is performed after the bonding and fixing.
The transformer-mounted circuit board according to any one of the above. 19. The transformer-mounted circuit board according to claim 13, wherein the board is a power supply board for incorporating a device.