JP3524314B2 - Transformer assembling method, transformer and transformer mounting board - Google Patents

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 is particularly preferably applicable to a transformer for a switching power supply device using a ferrite core used in a power supply device. Is.

[0002]

2. Description of the Related Art In general, a switching type power supply device has a merit that it can be made smaller and lighter than a dropper type power supply device and has a higher conversion efficiency. It is widely used for built-in built-in power supplies or 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.

A brief description of a transformer mounted on a substrate of such a switching type power supply device will be given with reference to FIGS. 9 and 10. FIG. 9 and FIG. 9 is a perspective view of FIG.
Shows a type in which a transformer and a core are fixed by an adhesive, and FIG. 10 shows a type in which a transformer and a core are fixed by varnish impregnation.

In FIG. 9, the coil 103 is wound around the bobbin 102, the core 101 is inserted into the opening of the bobbin 102, and the parts shown in the figure are fixed with adhesives 105 and 106. Trying to get. Further, in FIG. 10, a finished product is obtained by covering the entire outer peripheral surface with the varnish 108.

In the above configuration, each transformer 100 is configured to have a relatively flat shape, and contributes to reduction in size and weight after being mounted on the board.

However, the transformer 100
When each of the devices is formed into a small size and light weight and mounted on a substrate and then built in the device, a new problem arises in that it is exposed to an excessive impact load due to improper handling during transportation.

When the transformers 100 each having a small size and light weight and mounted on a board are used as a power source having a built-in AC adapter used on a desk, the power cord is hooked during use and the power source is turned on the desk. There was a problem that new measures were required to withstand an excessive impact load, assuming an accident such as falling from the ground.

When an impact load is applied in this way, on the power supply unit side, among various electronic parts constituting the power supply unit,
It has been found that excessive impact loads are concentrated on a relatively heavy transformer.

The damaged state of the transformer becomes serious when an external force in the direction of arrow F acts on the mounting board K as shown in FIG. 11, that is, when the external force acts, a moment in the direction of arrow M acts on the transformer 100. Then, at this time, the thin portion 1 on one side of the bobbin 102 fixed to the pattern portion of the substrate K by solder by the lead pin P of the transformer 100.
It is known that as a result of a sudden pulling force acting on 02a, a breakage phenomenon of the transformer that breaks from the thin portion 102a occurs.

Therefore, as a measure for preventing such breakage,
As shown in FIG. 12, in order to improve the breaking strength of the bobbin 102, the thin portion 102a integrally formed from both sides of the bobbin winding portion of the coil 103 is C-chamfered to take a reinforcing measure.

Alternatively, as disclosed in JP-A-6-96965 and JP-A-6-163278, the transformer main body is housed in an outer case that holds the entire transformer, and the gap is filled with resin. A fixing method is 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 outer dimension accuracy of the ferrite core used is There is a problem that it becomes difficult to withstand an excessive impact load such as a drop because a large gap is created between the ferrite core and the ferrite core.

Further, if the bobbin 102 is made thick enough to form a sufficient C chamfer in order to make the bobbin 102 of sufficient strength, the effective window area as a transformer can be set large. It disappears.
For this reason, there is a problem in that even the performance of the ferrite core built in the bobbin opening cannot be sufficiently drawn out.

On the other hand, as disclosed in Japanese Unexamined Patent Publication No. 7-300561, there has been proposed a method of using a resin having a high mechanical strength as the bobbin material itself. However, since the usable material of the transformer bobbin must meet all safety standards of each country such as UL standard, the material satisfying all of them is considerably higher in cost than the conventional material. There's a problem. Further, from the viewpoint of the actual use in the market, there is a problem that a large risk is involved in using a new material.

Further, as disclosed in the above-mentioned JP-A-6-96965 and JP-A-6-163278, a method of housing the transformer main body inside an outer case for holding the entire transformer and fixing it with resin filling is proposed. According to this, there is a disadvantage that not only the cost is increased, but also the transformer becomes large and heavy, and the advantages of the switching power supply device such as small size and light weight cannot be fully utilized.

Further, in order to increase the fracture resistance including the above-mentioned measures against dropping, it can be dealt with by applying an adhesive to the completed transformer, but the coefficient of linear expansion of the bobbin and the adhesive used is different. If so, unexpected problems such as core cracking due to the temperature change cycle will occur.

Therefore, the present invention has been made in view of the above-mentioned problems, and it is possible to increase the fracture resistance including countermeasures against dropping, to fully bring out the performance of the ferrite core, and to reduce the size and weight. An object of the present invention is to provide a transformer assembling method and a transformer and a transformer mounting board that can be configured and can prevent core cracking due to a temperature change cycle of the transformer itself during power supply operation.

[0018]

[Means for Solving the Problems]
In order to achieve the object, according to the present invention, a winding portion having a through hole portion for winding the primary side and the secondary side, and a primary side winding continuously formed from the through hole portion. A transformer assembling method comprising a bobbin integrally formed with a fixing portion and a secondary winding fixing portion and a magnetic material core which is inserted into the through hole portion and is provided so as to surround the winding, in the bonding step for bonding said magnetic material core between said primary winding fixed part and the secondary winding fixing unit, the
The magnetic material core and the primary winding fixing portion are made of the first adhesive.
The magnetic material core and the secondary winding fixing portion,
The second adhesive having a hardness different from that of the first adhesive is used for adhesion.
It is characterized in that that.

Further, a winding portion having a through hole portion for winding the primary side winding and the secondary side winding, a primary side winding fixing portion and a secondary side winding portion continuously formed from the through hole portion. A transformer comprising a bobbin integrally formed with a fixed part and a magnetic material core inserted into the through hole so as to surround the winding, the magnetic material core and the primary winding. The fixed part is first
The magnetic material core and the secondary
The side winding fixing portion has a second contact with a hardness different from that of the first adhesive.
It is characterized in that it is adhered by a binder .

[0020]

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be sequentially 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, the transformer used in the switching power supply device has a core 1 made of ferrite, a resin bobbin 2 for winding a winding wire, as shown in FIG.
A coil, which is 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 to obtain a safety standard. It is composed of a line portion 3. In addition, as shown in FIG. 2, the transformer is used after the pins are inserted into the mounting holes formed in the substrate K and then soldered and fixed.

As shown in FIGS. 1 and 2, the adhesive 4 serving as an adhesive means for fixing the bobbin 2 and the core 1 to each other is used for the primary winding side and the secondary winding of the collar portion of the bobbin 2. Each side is coated on both sides. This adhesive 4
Is an epoxy-based adhesive which is a thermosetting adhesive.

First for fixing the bobbin 2 and the core 1
The second adhesive 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. An epoxy adhesive that is a curable adhesive is used, and the adhesive 5 on the secondary winding fixing side is
Silicone type adhesive which is a thermosetting adhesive,
The hardness of the adhesive 4 after curing is set to be harder than that of the adhesive 5. Further, the silicone adhesive has a slightly lower adhesive strength with the magnetic core 1 than the epoxy adhesive, so that the silicone adhesive is applied and adhered to a wider area. Also,
The adhesive 6 is for fixing the magnetic cores 1 to each other.

On the other hand, the adhesive 7 has been generally customarily used in the past.
The adhesive is used to fix the magnetic core 1 and the bobbin 2, but is not essential at least in the present invention.

For example, in the conventional transformer, when an excessive shock such as dropping from the desk is applied to the power supply device, as a result, the power supply device is configured inside the power supply device. Of the parts, in the relatively heavy transformer, the moment M and the excessive impact are concentrated in the direction shown by the arrow in FIG.
However, it could not withstand this moment or impact, and it was relatively easy to break from the vicinity of the drawn part of the winding part.

During various drop experiments,
A drop experiment of a transformer in which the core 1 and the bobbin 2 are not fixed was conducted. At this time, since the core 1 and the bobbin 2 were not fixed, it was expected that the core 1 would crack, but as a result, cracks occurred at the positions 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 on the bobbin 2 side made of a resin material was insufficient.

Therefore, 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 side and the secondary winding side, respectively. As a result of conducting a drop test of the transformers provided respectively, the bonding strength between the bobbin 2 and the core 1 increased, so that the moment M and the impact force at the time of dropping are dispersed between the bobbin 2 and the magnetic core 1. The breaking force could be distributed. That is, it has been confirmed that the configuration as shown in the drawing makes it more resistant to damage when dropped as shown in FIG.

Further, the curing of the adhesives 4 and 5 used is made different from each other. That is, since the softer silicone-based adhesive 5 is configured to relieve (absorb) the stress due to the difference in linear expansion coefficient between the bobbin 2 and the core 1, it is caused by expansion and contraction during the temperature cycle. It is designed to prevent the occurrence of core cracks.

Furthermore, since the epoxy-based and silicone-based adhesives as the adhesives for fixing the bobbin 2 and the core 1 are thermosetting type, the heat generated by the self-heating during the operation of the transformer in the power supply device is generated. Since it is cured by the action of (1), there is no fear that the adhesive strength will be deteriorated due to softening, which is more preferable. It is also preferable from the viewpoint of usage record. [Second Embodiment] FIG. 3 is an external perspective view of a transformer according to a second embodiment of the present invention as viewed from the bottom, and FIG. 4 is a front view.

In both figures, the same reference numerals are given to the already described constitutions and the explanation is omitted, and the adhesive 6 is for fixing the magnetic cores 1 to each other, and the adhesive 7 is used.
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 described above, the adhesive 5 on the secondary winding fixing side for fixing the bobbin 2 and the core 1 is a silicone type 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 type adhesive.

This adhesive 8 is called, for example, a product name of Jet Sumit # 3748 manufactured by Sumitomo 3M,
Since it is a thermoplastic type adhesive, it has moderate softness, and it was confirmed that the impact at the time of dropping is alleviated to some extent.

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

By constructing the transformer as shown in FIGS. 3 and 4, the strength against drop can be maintained. Further, in addition to the effect of the first embodiment that there is no concern about core cracking due to a difference in linear expansion coefficient, an adhesive 8 is added to the transformer purchased as a normal component later as needed. This has the practical advantage of allowing the use of conventional transformers. [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 the present embodiment, if the description is omitted by giving the same reference numerals to the already described configurations, the basic structure of the transformer is the same as that described above.

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

In this case, the concentration of the varnish 9 used is
It is adjusted and managed so as to go around the gap between the bobbin 2 and the magnetic core 1 and to attach a certain amount.

Normally, a dimensional "play" is provided between the magnetic core 1 and the bobbin 2. Therefore, when the core 1 is assembled to the bobbin 2 and then flipped over when the varnish is impregnated, the magnetic core 1 A slight gap is created between the bobbin 2 and the core 1 due to the weight, but the varnish 9 wraps around this gap and the bobbin 2
The core and the core 1 are bonded and fixed.

Therefore, according to the third embodiment, it is possible to take measures against a drop like 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, as compared with the first and second embodiments, the surface adhesion is such that the varnish 9 penetrates into the gap between the core 1 and the bobbin 2, so that only the adhesive is fixed. The squealing phenomenon of the transformer due to the natural frequency, which tends to occur at times, is eliminated, and it is possible to take measures against the drop at a lower cost. [Fourth Embodiment] FIG. 7 is a perspective view of a transformer showing a fourth embodiment of the transformer as seen from the lower surface, and FIG. 8 is a front view showing the structure thereof.

In the present embodiment, the same reference numerals are given to the already-explained configurations, and the description will be omitted. The characteristic feature of the basic structure of the transformer is that the 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. 9 is used, and hot melt 8 which is a thermoplastic adhesive is further adhered from above the varnish 9 and solidified.

That is, after impregnating the varnish, hot melt (for example, Sumitomo 3
Adhesive 8 using a product name of company M: jet melt melt # 3748) is added.

When the transformer having such a structure is dropped from the desk (about 75 cm) onto the floor, the
It was possible to obtain a product that does not break even when dropped. As described above, there is an advantage that a sufficient adhesive strength can be provided.

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

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

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

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, the temperature change cycle of the transformer itself during power supply operation Since it is possible to stop the core from bobbin on both sides of the transformer after preventing the core from cracking, it is possible to obtain a transformer that maintains 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 manufacturing process of the transformer.

As an adhesive having different hardness,
One uses an epoxy adhesive that is widely popular, and the other silicone adhesive that is also widely used, so it is easy to obtain, and as required by safety standards for power transformers, For example, there is an advantage that the degree of freedom in selecting an adhesive that meets the standards for UL flame-retardant materials is expanded.

Further, one of the adhesives having different hardness is an epoxy adhesive which is a thermosetting adhesive,
On the other hand, by using the hot melt type which is a thermoplastic adhesive, it is possible to work on the assembly process side of the power supply, if necessary, for the transformer purchased as a normal component later. There is an advantage that the transformer as it is can be used.

Further, since the hot melt adhesive is a material that has been used in the past, it has the advantage that it can be used easily and safely in the production line. Also, one of the adhesives having different hardness, one is an epoxy adhesive and the other uses a varnish impregnated with a transformer as an adhesive means. Therefore, there is an advantage that the squeal phenomenon of the transformer due to the natural frequency that tends to occur when only the adhesive is fixed does not occur, and it is possible to take measures against the drop at a lower cost.

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

[0056]

As described above, according to the present invention,
It is possible to increase the fracture strength including measures against dropping, to fully utilize the performance of the ferrite core, to make it compact and lightweight, and to 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.

[0057]

[Brief description of drawings]

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

FIG. 2 is a front view of the transformer of FIG. 1 mounted on a substrate K.

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

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

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 the transformer according to the fourth embodiment as seen from the lower surface.

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

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 showing a destruction phenomenon of a transformer after a drop test by a conventional method.

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

[Explanation of symbols]

1 magnetic core 2 bobbin 3 winding part 4 epoxy adhesive 5 for fixing bobbin 2 and core 1 silicone adhesive 6 for fixing bobbin 2 and core 1 fixing cores 1 to each other Adhesive 8 for hot-melt adhesive 9 Varnish (adhesive means)

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Claims (14)

(57) [Claims] 1. A winding portion having a through hole portion for winding a primary side winding and a secondary side winding, a primary side winding fixing portion and a secondary side winding portion continuously formed from the through hole portion. 1. A transformer assembling method comprising a bobbin integrally formed with a fixing portion and a magnetic material core which is inserted into the through hole portion and is provided so as to surround the winding, the magnetic material core comprising: In a bonding step for bonding between the secondary winding fixing portion and the secondary winding fixing portion, the magnetic material core and the primary winding fixing portion are bonded with a first adhesive, The transformer assembly method, wherein the magnetic material core and the secondary winding fixing portion are bonded together by a second adhesive having a hardness different from that of the first adhesive. 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 adhesive, and the second adhesive is a silicone adhesive. 4. The transformer assembling method according to claim 1, wherein the first adhesive is a thermosetting adhesive, and the second adhesive is a thermoplastic adhesive. 5. The transformer assembling method according to claim 4, wherein the thermosetting adhesive is an epoxy adhesive, and the thermoplastic adhesive is a hot-melt adhesive. . 6. The transformer assembling 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. A hot melt adhesive is further applied to the primary winding fixing portion or the secondary winding fixing portion side which is not fixed with the epoxy adhesive after the impregnation treatment. The transformer assembling method according to claim 6, further comprising a step. 8. A winding portion having a through hole portion for winding primary and secondary windings, a primary winding fixing portion and a secondary winding portion continuously formed from the through hole portion. A transformer comprising a bobbin integrally formed with a fixed part and a magnetic material core inserted into the through hole so as to surround the winding, the magnetic material core and the primary winding. The fixing portion is bonded by a first adhesive, and the magnetic material core and the secondary winding fixing portion are bonded by a second adhesive having a hardness different from that of the first adhesive. A transformer. 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 adhesive and the second adhesive is a silicone 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 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 side winding fixing portion or the second winding fixing portion which is 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.