JP3203892B2 - Manufacturing method of inductor parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin cast type inductor component used for various electronic devices.

[0002]

2. Description of the Related Art In recent years, in order to meet the needs for miniaturization and high safety of inductor components, resin cast casing technology has been widely used.

[0003] Casting resins naturally have excellent electrical insulation properties and workability for injection, but those which meet the following requirements for important performance are the mainstream.

(1) In order to reduce the size, a device having high thermal conductivity is required. For this reason, silica or the like is added as a filler to the base resin to increase the thermal conductivity.

(2) Shortening of curing steps, downsizing of equipment, and energy saving are required. For this reason, low-temperature, short-time curing types are often used. Generally, epoxy, silicone, polyurethane, and the like are used as the casting resin. FIG. 6 shows a general structure of an inductor component using the resin casting casing technique.

Hereinafter, the structure of the resin cast type inductor component will be described with reference to FIG. In FIG. 6, 11 is a coil bobbin, 12 is a coil, 13 is a ferrite core, 14 is a case, 15 is a casting resin, and 16 is a bottom plate.

Referring to FIG. 6, a coil 12 is wound around a coil bobbin 11 and a ferrite core 13 is assembled to complete an inductor component body. Next, an injection molding resin 15 is poured into a case 14 having an opening on one side and prepared in advance, and the inductor component body and the bottom plate 16 are mechanically coupled to the prepared case 14 in an upward direction. After that, the casting resin 15 is cured and completed. For curing the casting resin 15, a method of heating and curing is generally used.

[0008]

However, in the above configuration, first, the main body of the inductor component is covered with the casting resin 15. Further, in order to reduce the temperature rise of the inductor component body, a large amount of filler such as silica is added to the casting resin 15 to further increase the thermal conductivity.

For this reason, the casting resin 15 has a high elastic modulus and a large internal stress. Further, the casting resin 15 is cured at a low temperature in order to save energy. Therefore, the upper limit of the temperature rating of the inductor component and the casting resin 15
However, there has been a problem that the temperature difference from the solidification temperature increases and the thermal stress also increases.

For the above reasons, when the cast type inductor component is used or subjected to a reliability test at the maximum temperature of its temperature rating, the stress caused by the cast resin 15 increases, and the ferrite core 13, the case 14, the cast There has been a problem in reliability that cracks are generated in the resin 15 and inductance and insulation properties are deteriorated.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and has a high reliability in which cracks do not occur in a ferrite core, a case, and a casting resin even when a casting type inductor component reaches a maximum temperature state of its temperature rating. An object of the present invention is to provide a method for manufacturing a resin cast type inductor component.

[0012]

In order to achieve the above-mentioned object, an inductance component according to the present invention uses a two-pack type casting resin.
Recon resin and solidified into two-part silicone resin
A control agent that slows down the reaction rate was added, and the control agent was added.
Two-component silicone resin is used for the temperature rating of the inductor parts.
Curing furnace at a temperature higher than the upper limit minus 20 ° C
It is configured to be solidified by .

[0013]

According to the above configuration, the temperature difference between the solidification temperature of the casting resin and the upper limit of the temperature rating of the inductor component is reduced,
Since the thermal stress of the casting resin in the maximum temperature state is reduced, the problem that cracks occur in the ferrite core, the case, and the casting resin is solved.

[0014]

EXAMPLES (Example 1) Hereinafter, a first example of an inductor component of a resin casting type according to the present invention will be described.
It will be described with reference to FIG. 4 of Example from FIG.

FIG . 1 is a resin injection molding showing a first embodiment of the present invention.
FIG. 6 is a cross-sectional view of a mold type inductor component, and the structure is shown in FIG.
Same as conventional cast resin type inductor parts shown in
It is. The casting resin type shown in the first embodiment of the present invention
For the inductor parts, replace the casting resin with two-liquid silicone resin.
And slow down the solidification reaction rate to the two-part silicone resin.
To control the temperature of the inductor parts.
Temperature higher than the value obtained by subtracting 20 ° C from the upper limit of the temperature rating
There is a difference from the conventional one in that it is solidified in a furnace.

First, the casting resin 5 in FIG.
Solidification temperature and ferrite core 3 when used as recon resin
Table 1 shows the experimental results of the temperature at which cracks occur.

[0017]

[Table 1]

The casting resin 5 having a low solidification temperature is cured for a long time, and the one having a high solidification temperature is cured for a short time. From Table 1, it can be seen that the higher the solidification temperature of the casting resin 5, the higher the temperature at which cracks occur in the ferrite core 3 than the lower one. Further, it can be seen that the temperature at which cracks occur in the ferrite core 3 is higher by 30 to 45 ° C. than the solidification temperature of the casting resin 5.

FIG. 2 shows that the casting resin 5 was heated at 30.degree.
It is a figure which shows the temperature and stress of what was solidified at ° C. FIG. 2 shows that the temperature of the casting resin 5 and the stress are in a proportional relationship, and the stress increases as the temperature difference with respect to the solidification temperature of the casting resin 5 increases. Conversely, if the temperature difference is reduced, the stress can be reduced.

According to Table 1 and FIG. 2, the maximum temperature at which the inductor component is used is 30 ° C. from the upper limit of the temperature rating.
If the casting resin 5 is solidified at a temperature higher than the subtracted value , cracks do not occur in the ferrite core 13 even when the inductor component of each temperature rating is used or subjected to a reliability test at its maximum temperature. I can say. However, when the number of samples was increased and experiments were performed to take account of variations, it was found that the casting resin 5 had to be solidified at a temperature higher than a value obtained by subtracting 20 ° C. from the upper limit of the temperature rating of the inductor component.

[0021]

FIG . 3 shows two-part silicone resin and casting resin 5.
And using this two-component silicone resin temperature setting 120
It is a figure which shows the data which measured the temperature which solidifies in a hardening furnace of ° C.

FIG. 3 shows that the two-pack type resin used for the casting resin 5 was used.
Even if the recon resin is heated in a curing oven at a set temperature of 120 ° C,
When the temperature of the casting resin 5 rises to 90 ° C.,
It can be seen that the two-part silicone resin solidified. From this fact, for the cast resin type inductor component having a temperature rating of 105 ° C. (class A), the solidification temperature of the cast resin 5 is 85 ° C. (1
05 ° C-20 ° C) or more, but those with a temperature rating of 120 ° C (class E) satisfy the conditions of 100 ° C (120 ° C-20 ° C) or more of the solidification temperature of the casting resin 5. Can not do it. As a matter of course, the temperature ratings of 130 ° C. (class B) and 155 ° C. (class F) cannot be satisfied.

Therefore, attention was paid to the curing reaction rate of the casting resin 5, and a study was made to increase the solidification temperature of the casting resin 5 by delaying the curing reaction rate.

FIG. 4 is a diagram showing data obtained by adding a control agent for slowing down the solidification reaction rate to the two-part silicone resin, and measuring the amount of addition and the solidification temperature. As shown in FIG. 4 , when the control agent is added, the solidification reaction speed is reduced , and the solidification reaction of the casting resin 5 is reduced.
It is possible to secure time for the temperature of the casting resin 5 to rise before starting
It was found that the solidification temperature of the casting resin 5 could be increased, and the solidification temperature could be further increased by increasing the amount of addition.

As described above, the casting resin 5 is used as a two-part sealant.
Recon resin and solidified into two-part silicone resin
A control agent that slows down the reaction rate was added, and the control agent was added.
The upper limit of the temperature rating of inductor components using two-part silicone resin
Solidify at a temperature higher than the value obtained by subtracting 20 ° C from the value.
Thus, the solidification temperature of the casting resin 5 can be increased.
Even if the inductor component is used at the upper temperature limit,
No cracks occur in the light core 3
4. No cracks occur in the casting resin 5
By adjusting the amount of the control agent added,
Solidification temperature can be adjusted arbitrarily, product size and curing oven
Can respond to different product heating curves depending on the performance of
You. The temperature rating is 105 ° C (class A), 120 ° C (E
Seed), 130 ° C (class B), 155 ° C (class F) casting resin
Casting agent for commercializing type inductor components
It can be realized by using

[0027] (Example 2) Hereinafter, a second inductor component of the resin casting type of the present invention
The embodiment will be described with reference to FIG. FIG. 5 is a diagram showing a temperature rise curve of a product ( casting resin 5 portion ) when the casting resin 5 is cured in a curing furnace. The temperature rise curve (A) is data at a setting temperature of the curing furnace of 120 ° C., and the temperature rising curve (B) is data at a temperature setting of the curing furnace of 140 ° C.

From FIG. 5, it can be seen that the temperature rise curve of the casting resin portion starts to saturate at a point of minus 15 to 20 ° C. of the temperature setting value of the curing furnace. Also, it can be seen that the higher the temperature setting value of the curing furnace, the faster the temperature of the casting resin portion is raised to a certain target value.

From this, when the temperature setting value of the curing furnace is set to be equal to or lower than the upper limit of the temperature rating of the inductor component, the casting resin 5 is solidified at a temperature higher than the upper limit of the temperature rating of the inductor component minus -20 ° C. To achieve this, the curing time must be extended.

From the above, by setting the temperature setting value of the curing furnace higher than the upper limit value of the temperature rating of the inductor component, it is possible to increase the temperature of the casting resin portion quickly and to increase the temperature at which saturation begins. It is possible to shorten the curing time in the curing step of the casting resin 5, reduce the size of the curing furnace, and allow some temperature fluctuation of the curing furnace.
High quality cast resin type inductor parts can be realized.

[0031]

As described above, according to the method for manufacturing an inductor component of the present invention, the casting resin is a two-part silicone resin.
In addition, two-component silicone resin has a system that slows down the solidification reaction rate.
By adding a control agent and solidifying the two- part silicone resin to which the control agent is added at a temperature higher than the temperature obtained by subtracting 20 ° C. from the upper limit of the temperature rating of the inductor component, (1) ) At the highest temperature rating, ferrite core,
Cracks do not occur in the case and the casting resin.

Further, a two-component silicone is used as the liquid resin to be injected into the case, and a control agent for delaying the curing reaction is added to this liquid resin in an appropriate amount so as to reach an optimum solidification temperature. Accordingly, (2) it is possible to cope with a case where the temperature rise curve of the product differs depending on the size of the product and the performance of the curing furnace.

(3) Temperature rating 105 ° C (class A) 120 ° C
Inductor components of (class E) 130 ° C (class B) 155 ° C (class F) can be commercialized using the same casting resin.

Further, by setting the liquid resin injected into the case into a solidified casting resin in a curing furnace set at a temperature higher than the upper limit of the temperature rating of the inductor component,
(4) The curing time in the curing step of the casting resin can be shortened, the size of the curing furnace can be reduced, and the temperature of the curing furnace can be slightly changed. Thus, it is possible to provide a highly reliable cast resin type inductor component at a low cost, which is of great industrial value.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a resin cast type inductor component showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between temperature and stress of a casting resin of the inductor component of the same resin casting type.

FIG. 3 is a diagram showing a temperature at which the two-liquid silicone resin of the inductor component of the same resin casting type solidifies in a curing furnace at a temperature setting of 120 ° C.

FIG. 4 is a diagram showing a control agent for slowing down a curing reaction rate added to a two-component silicone resin of an inductor component of the same resin casting type, and the addition amount and solidification temperature.

FIG. 5 is a diagram showing a temperature curve of a product in a curing furnace for a resin cast type inductor component according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a conventional resin cast type inductor component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil bobbin 2 Coil 3 Ferrite core 4 Case 5 Casting resin 6 Bottom plate

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-146213 (JP, A) JP-A-57-15235 (JP, A) JP-A-57-144739 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01F 17 / 04,27 / 02,27 / 32 H01F 41 / 04,41 / 12

Claims (2)

(57) [Claims] An inductor component body in which a ferrite core is incorporated in a coil wound around a coil bobbin is housed in a case, and a liquid casting resin is injected into the case.
In particular, the manufacture of inductor parts for thermally curing the casting resin
In the manufacturing method, the casting resin is converted into a two-part silicone resin.
And the solidification reaction rate of the two-part silicone resin
The control agent is added, and the control agent is added.
Two-component silicone resin is used for the temperature rating of the inductor parts.
Curing furnace at a temperature higher than the upper limit minus 20 ° C
Manufacturing method of inductor components solidified by. 2. The method for manufacturing an inductor component according to claim 1, wherein the temperature of the curing furnace is set to a temperature higher than the upper limit of the temperature rating of the inductor component.