JPH10241977A - Transformer assembling method, transformer and transformer mounting board - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the breakdown strength including the measures against dropping, to fully exploit the performance of ferrite cores, and to be able to make it compact and lightweight, and to change the temperature of the transformer itself during power supply operation. Prevents core cracking due to cycles. SOLUTION: A bobbin 2 having a through-hole portion through which primary and secondary windings are formed, and a bobbin 2 integrally formed with a primary winding fixing portion and a secondary winding fixing portion. In order to form a transformer from the magnetic material core 1 and to bond the magnetic material core 1 to the primary winding fixing portion and the secondary winding fixing portion,
A first adhesive 4 and a second adhesive 5 having different hardnesses are used.

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 a substrate of such a switching type power supply device will be briefly described. FIGS. 9 and 10 show the appearance of a transformer 100 generally used conventionally. FIG. 9 is a perspective view,
Is a type in which a transformer and a core are fixed by an adhesive, and FIG. 10 is a type in which the transformer and the core are fixed by varnish impregnation.

In FIG. 9, 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 figure are fixed by the adhesives 105 and 106. I'm trying to get In FIG. 10, a finished product is obtained by covering the entire outer peripheral surface with the varnish 108.

[0005] In the above configuration, each transformer 100 is configured to be comparatively flat, so as to contribute to reduction in size and weight after being mounted on a board.

However, as described above, the transformer 100
In the case where each of them is configured to be small and light and mounted on a substrate, and then incorporated in a device, there is a new problem that the device is exposed to an excessive impact load due to improper handling or the like during carrying.

If the transformer 100 is configured as a small and lightweight AC adapter for use on a desk and used as a built-in power supply, the power supply cord is hooked during use and the power supply is There is a problem that a new countermeasure for withstanding an excessive impact load is required in anticipation of an accident such as a fall from the vehicle.

[0008] 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. 11, 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,
As shown in FIG. 12, in order to improve the breaking strength of the bobbin 102, a thinner portion 102a integrally formed from both sides of the bobbin winding portion of the coil 103 is chamfered with a C-chamfer to take reinforcement measures.

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.

[0012]

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.

Further, 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 even the performance of the ferrite core built in the bobbin 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. 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 in an outer case for holding the entire transformer and fixing it 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.

In order to increase the breaking strength including the above-mentioned measures against dropping, it is possible to cope with the problem by applying an adhesive to the completed transformer, but the difference in the linear expansion coefficient between the bobbin and the adhesive used is different. If there is, an unexpected problem such as the occurrence of a core crack due to a temperature change cycle will occur.

Accordingly, the present invention has been made in view of the above-mentioned problems, and can improve the breakdown strength including measures against dropping, can sufficiently bring out the performance of a ferrite core, and can reduce the size and weight. It is an object of the present invention to provide a transformer assembling method, a transformer, and a transformer mounting board that can be configured and that can prevent core breakage due to a temperature change cycle of the transformer itself in power supply operation.

[0018]

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 on which primary and secondary windings are performed, and a primary winding continuously formed from the through-hole portion A transformer assembling method for forming a transformer from a bobbin integrally formed with a fixing part and a secondary winding fixing part, and a magnetic material core inserted into the through hole and provided so as to surround the winding, In the bonding step for bonding the magnetic material core and the primary winding fixing part and the secondary winding fixing part, a first adhesive and a second adhesive having different hardnesses are used. It is characterized by using.

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. A transformer comprising: a bobbin integrally formed with a fixed portion; and a magnetic material core inserted into the through-hole portion and provided to surround the winding, wherein the magnetic material core; In order to bond between the wire fixing portion and the secondary winding fixing portion, a first adhesive and a second adhesive having different hardnesses are used.

A winding portion having a through-hole portion through which primary and secondary windings are formed, a primary-side winding fixed portion and a secondary-side winding formed continuously from the through-hole portion. A transformer mounting substrate, wherein a transformer comprising a bobbin integrally formed with a fixed portion and a magnetic material core inserted into the through-hole portion and provided to surround the winding is mounted on the substrate, wherein the magnetic material is In the bonding step for bonding the core and the primary winding fixing part and the secondary winding fixing part, the first adhesive and the second adhesive having different hardnesses are used. It is characterized by implementing a transformer.

[0021]

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 the first embodiment of the transformer, and FIG. 2 is a front view of FIG.

1 and 2, a transformer used in a switching power supply device includes a core 1 made of ferrite, a bobbin 2 made of resin for winding a winding, as shown in FIG.
A coil wound by a predetermined winding method using a winding, an interlayer insulating tape, and a barrier tape for securing a primary-secondary distance required for obtaining a safety standard. And a line portion 3. As shown in FIG. 2, the transformer is used after pins are inserted into mounting holes formed in the substrate K, and then soldered and fixed.

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 of the flange portion of the bobbin 2 and the secondary winding. It is applied on both sides of each side. This adhesive 4
Is an epoxy adhesive which is a thermosetting adhesive.

The first for fixing the bobbin 2 and the core 1
And the second adhesive are the adhesive 4 on the primary winding fixing part side and the adhesive 5 on the secondary winding fixing part side, and the adhesive 4 on the primary winding side is heat An epoxy-based adhesive, which is a curable adhesive, is used. The adhesive 5 on the secondary winding fixed side is:
It is a silicone-based adhesive that is a thermosetting adhesive,
The hardness of the adhesive 4 after curing is set to be harder than that of the adhesive 5. Further, since the adhesive strength of the silicone-based adhesive is slightly lower than that of the epoxy-based adhesive, the silicone-based adhesive is applied over a wider area and adhered. Also,
The adhesive 6 is for fixing the magnetic cores 1 to each other.

On the other hand, the adhesive 7 has been used in a generally customary manner.
An adhesive used for fixing the magnetic core 1 and the bobbin 2, but is not essential at least in the present invention.

For example, in a conventional transformer, when an excessive impact such as dropping from a desk is applied to a power supply device, as a result, the power supply device is configured inside the power supply device. Among the components, in a relatively heavy transformer, the moment M and excessive impact concentrate in the direction shown by the arrow in FIG.
However, it was not able to withstand the moment and the impact, and there was a case where it was relatively easily broken from the vicinity of the winding portion lead portion.

In conducting various drop experiments,
A drop experiment of a transformer in which the core 1 and the bobbin 2 were not fixed was performed. At this time, since the core 1 and the bobbin 2 were not fixed, it was expected that the core 1 would break, but as a result, the crack occurred at a position as shown in FIG.
From this, it was found that in this case, the impact resistance of the magnetic core 1 was sufficient, but the strength of the bobbin 2 made of a resin material was insufficient.

As a countermeasure against this, as shown in FIGS. 1 and 2, adhesives 4 and 5 for fixing the bobbin 2 and the core 1 are provided on both sides of the primary winding and the secondary winding, respectively. As a result of performing the drop test of the transformers provided respectively, the adhesive strength between the bobbin 2 and the core 1 was increased. Therefore, the moment M and the impact force at the time of drop were dispersed between the bobbin 2 and the magnetic core 1, The breaking force could be dispersed. That is, it was confirmed that the configuration as shown in the drawing is strong against destruction at the time of falling as shown in FIG.

The curing of the adhesives 4, 5 used is different from each other. That is, the softer silicone adhesive 5 is configured to relieve (absorb) the stress caused by the difference in the linear expansion coefficient between the bobbin 2 and the core 1, which causes expansion and contraction during a temperature cycle. Core breakage can be prevented.

Further, since the epoxy-based and silicone-based adhesives as adhesives for fixing the bobbin 2 and the core 1 are thermosetting, the heat generated by self-heating during the operation of the transformer in the power supply device. This is more preferable because it hardens itself by the action of, and there is no fear that the adhesive strength is reduced by softening. Moreover, it is preferable also from a viewpoint of use results. Second Embodiment FIG. 3 is an external perspective view of a transformer according to a second embodiment of the present invention as viewed from below, and FIG. 4 is a front view.

In both figures, the same reference numerals are given to the components already described and the description is omitted. The adhesive 6 is for fixing the magnetic cores 1 to each other, and the adhesive 6
Is an adhesive for fixing the core 1 and the bobbin 2 which are not directly related to the present invention (there is no meaning of reinforcement).

In the first embodiment, the adhesive 5 on the secondary winding fixing side for fixing the bobbin 2 and the core 1 is a silicone-based adhesive which is a thermosetting adhesive. However, in the present embodiment, the adhesive 8 on the secondary winding fixing side for fixing the bobbin 2 and the magnetic core 1 is
It is a hot melt which is a thermoplastic adhesive.

The adhesive 8 is, for example, a product name of Jetmelt # 3748 of Sumitomo 3M Company.
Since it is a thermoplastic adhesive, it has an appropriate softness, and it has been confirmed that the impact at the time of dropping is reduced to some extent.

As shown in the figure, an adhesive 8 is applied between the bobbin 2 and the winding 3 so as to face the substrate mounting surface.

By configuring the transformer as shown in FIGS. 3 and 4, strength against falling can be maintained. Further, in addition to the effect of the first embodiment described above such that there is no fear of core cracking due to a difference in linear expansion coefficient, an adhesive 8 is added to a transformer purchased as a normal component as necessary. This has the practical advantage that a conventional transformer can be used. [Third Embodiment] FIG. 5 is a plan view showing the structure of a transformer according to a third embodiment, and FIG. 6 is a front view showing the structure of the transformer in the mounting direction.

In this embodiment, the same reference numerals are given to the components already described, and the description is omitted. The basic structure of the transformer is the same as that described above.

As shown in FIGS. 5 and 6, an adhesive for fixing the bobbin 2 and the magnetic core 1 is used.
The adhesive 4 on the secondary winding fixed side is an epoxy adhesive which is a thermosetting adhesive, and a varnish 9 for impregnating a transformer is used as the bonding means on the secondary winding fixed side. .

In this case, the concentration of the varnish 9 used is
It is adjusted and managed so that it goes around the gap between the bobbin 2 and the magnetic core 1 and that a certain amount is attached.

Normally, since there is a dimensional “play” between the magnetic core 1 and the bobbin 2, if the core 1 is assembled to the bobbin 2 and then turned over when impregnating with varnish, the magnetic core 1 Although a small gap is formed between the bobbin 2 and the core 1 by the weight, the varnish 9 goes into this gap, and the bobbin 2
And the core 1 are bonded and fixed.

Therefore, according to the third embodiment, it is possible to take measures against falling down as in the other embodiments, and there is no fear of core cracking due to a difference in linear expansion coefficient.

Further, according to the third embodiment, compared with the first and second embodiments, the varnish 9 permeates into the gap between the core 1 and the bobbin 2, so that the adhesive is fixed only by the adhesive. Transformer squealing phenomena due to the natural frequency, which often occurs, are eliminated, and a countermeasure against dropping can be taken at lower cost. Fourth Embodiment FIG. 7 is an external perspective view of a transformer according to a fourth embodiment of the present invention as viewed from below, and FIG. 8 is a front view showing the structure thereof.

In the present embodiment, the same reference numerals are given to the components already described, and the description thereof will be omitted. The basic feature of the transformer structure is that the above-described second and third embodiments are combined. That is the point.

That is, the adhesive 4 on the primary winding fixed side is an epoxy adhesive which is a thermosetting adhesive, and the secondary winding fixed side adhesive means is a varnish impregnated with a transformer. The varnish 9 is solidified by further attaching a hot melt 8 which is a thermoplastic adhesive on the varnish 9.

That is, after the varnish is impregnated, a hot melt (eg, Sumitomo 3)
This is a product to which an adhesive 8 using a trade name of a company M: jet melt melt # 3748) is added.

When the transformer having such a structure is dropped on the floor from a desk (about 75 cm), the transformer is moved in the same direction.
A material that does not break even when dropped repeatedly was obtained. As described above, there is an advantage that a sufficient adhesive strength can be provided.

In each of the embodiments described above, the transformer of the horizontal core is described. However, the present invention can be applied to a transformer of a so-called vertical core.

The primary winding fixed side and the secondary winding fixed side may be switched and the adhesives 4 and 5 may be applied, and the same effect can be obtained.

Further, even when the present invention is applied to the transformer described with reference to FIGS. 9 and 10, it is needless to say that the effect of the present invention can be obtained.

As described above, since the adhesive on the primary winding fixed side and the adhesive on the secondary winding fixed side are different in hardness from each other, the temperature change cycle of the transformer itself in the power supply operation. Since the core can be stopped at the bobbin on both sides of the transformer while preventing the core from cracking, it is possible to obtain a transformer having a low drop strength.

Further, since the adhesives having different hardnesses are both thermosetting adhesives, there is an advantage that the adhesives can be cured in the same step in the process of manufacturing the transformer.

As adhesives having different hardnesses,
One uses an epoxy-based adhesive that is widely used in general, and the other uses a silicone-based adhesive that is widely used in general, so that it is easily available and required by safety standards for power transformers. For example, there is an advantage that the degree of freedom in selecting an adhesive satisfying the standard of UL flame retardant material is widened.

One of the adhesives having different hardnesses is an epoxy adhesive which is a thermosetting adhesive,
On the other hand, the use of a hot-melt type thermoplastic adhesive allows the transformer purchased as a normal part to be worked later on the power supply assembly process side, if necessary. There is an advantage that the transformer can be used as it is.

Also, since the hot melt adhesive is a material which has been used in the past and has a proven track record, there is an advantage that it can be easily and safely used on a production line. Further, one of the adhesives having different hardnesses is an epoxy-based adhesive, and the other uses a varnish impregnated with a transformer as an adhesive means, so that the varnish penetrates into the gap between the core and the bobbin, so that surface bonding is performed. Therefore, there is no merit that the transformer squeals due to the natural frequency that is likely to occur when only the adhesive is fixed are eliminated, and a countermeasure against dropping can be taken at lower cost.

After the varnish is impregnated, by adding an adhesive using a hot melt to the side not fixed with the epoxy adhesive, there is an advantage that the drop strength can be further increased.

[0056]

As described above, according to the present invention,
It can increase the breakdown strength including the measures against dropping, can fully exploit the performance of the ferrite core, can be configured to be small and lightweight, and can prevent core cracking due to the temperature change cycle of the transformer itself during power supply operation. It is possible to provide a transformer assembling method, a transformer and a transformer mounting board that can be provided.

[0057]

[Brief description of the drawings]

FIG. 1 is a plan view of a transformer according to a first embodiment.

FIG. 2 is a front view in which the transformer of FIG.

FIG. 3 is an external perspective view of a transformer according to a second embodiment viewed from a lower surface (substrate mounting surface) side.

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

FIG. 5 is a plan view of a transformer according to a third embodiment.

FIG. 6 is a front view of the transformer of FIG.

FIG. 7 is an external perspective view of a transformer according to a fourth embodiment as viewed from below.

FIG. 8 is a front view of the transformer of FIG. 7;

FIG. 9 is an external perspective view of a conventional transformer in which a core and a bobbin are fixed with an adhesive.

FIG. 10 is an external perspective view of a conventional transformer in which a core and a bobbin are fixed by varnish impregnation.

FIG. 11 is a front view illustrating a transformer breakdown phenomenon after a drop test according to a conventional method.

FIG. 12 is a front view (a) and a right side view (b) of a bobbin for improving the breaking strength of the bobbin.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic core 2 Bobbin 3 Winding part 4 Epoxy adhesive for fixing bobbin 2 and core 1 5 Silicone adhesive for fixing bobbin 2 and core 6 6 Fixing cores 1 8 hot melt adhesive 9 varnish (adhesion means)

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

Claims (22)

[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. 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 and provided so as to surround the winding, wherein the magnetic material core; In the bonding step for bonding between the secondary winding fixing part and the secondary winding fixing part,
A method for assembling a transformer, comprising using a first adhesive and a second adhesive having different hardnesses. 2. The transformer assembling method according to claim 1, wherein both the first adhesive and the second adhesive are thermosetting adhesives. 3. The transformer assembling method according to claim 2, wherein the first adhesive is an epoxy-based adhesive, and the second adhesive is a silicone-based adhesive. 4. The method according to claim 1, wherein the first adhesive is a thermosetting adhesive, and the second adhesive is a thermoplastic adhesive. 5. The method according to claim 4, wherein the thermosetting adhesive is an epoxy-based adhesive, and the thermoplastic adhesive is a hot-melt adhesive. . 6. The method according to claim 1, wherein the first adhesive is an epoxy adhesive, and a varnish for impregnation is used as the second adhesive. . 7. After the impregnation, a hot-melt adhesive is further applied to the primary winding fixing portion or the secondary winding fixing portion not fixed with the epoxy adhesive. 7. The method according to claim 6, further comprising the steps of: 8. A winding portion having a through-hole portion through which primary and secondary windings are formed, a primary winding fixing portion and a secondary winding continuously formed from the through-hole portion. A transformer comprising: a bobbin integrally formed with a fixed portion; and a magnetic material core inserted into the through-hole portion and provided to surround the winding, wherein the magnetic material core; A transformer, wherein a first adhesive and a second adhesive having different hardnesses are used for bonding between a wire fixing portion and the secondary winding fixing portion. 9. The transformer according to claim 8, wherein both the first adhesive and the second adhesive are thermosetting adhesives. 10. The transformer according to claim 9, wherein the first adhesive is an epoxy-based adhesive, and the second adhesive is a silicone-based adhesive. 11. The transformer according to claim 8, wherein the first adhesive is a thermosetting adhesive, and the second adhesive is a thermoplastic adhesive. 12. The transformer according to claim 9, wherein the thermosetting adhesive is an epoxy-based adhesive, and the thermoplastic adhesive is a hot-melt adhesive. 13. The transformer according to claim 8, wherein the first adhesive is an epoxy adhesive, and a varnish for impregnation is used as the second adhesive. 14. The primary winding fixing part or the secondary winding not fixed with the epoxy adhesive after the impregnation treatment.
14. The transformer according to claim 13, wherein a hot-melt adhesive is further applied to the secondary winding fixing portion side. 15. A winding portion having a through-hole portion through which primary and secondary windings are formed, a primary winding fixing portion and a secondary winding continuously formed from the through-hole portion. A transformer mounting substrate, wherein a transformer comprising a bobbin integrally formed with a fixed portion and a magnetic material core inserted into the through-hole portion and provided to surround the winding is mounted on the substrate, In a bonding step for bonding between the core and the primary winding fixing portion and the secondary winding fixing portion,
A transformer mounting board on which a transformer using a first adhesive and a second adhesive having different hardnesses is mounted. 16. The transformer mounting board according to claim 15, wherein both the fifteenth adhesive and the second adhesive are thermosetting adhesives. 17. The transformer mounting board according to claim 16, wherein the first adhesive is an epoxy-based adhesive, and the second adhesive is a silicone-based adhesive. 18. The transformer mounting board according to claim 15, wherein the first adhesive is a thermosetting adhesive, and the second adhesive is a thermoplastic adhesive. 19. The transformer mounting board according to claim 18, wherein the thermosetting adhesive is an epoxy-based adhesive, and the thermoplastic adhesive is a hot-melt adhesive. . 20. The transformer mounting board according to claim 15, wherein the first adhesive is an epoxy-based adhesive, and a varnish for impregnation is used as the second adhesive. . 21. The primary winding fixing portion or the secondary winding not fixed with the epoxy adhesive after the impregnation treatment.
21. The method according to claim 20, further comprising a step of further applying a hot-melt adhesive to the secondary winding fixing portion side.
The transformer mounting board according to the above. 22. The transformer mounting board according to claim 15, wherein the board is a power board for incorporating a device or a power board for an AC adapter.