JPH05190708A - Electronic parts - Google Patents

Abstract

PURPOSE:To elevate the fire retardancy, the tracking resistance, and the arc ignition resistance in the exposed layer of a resin injection type of electronic part, and elevate the electric property inside the injected resin and the adhesion with an element and the moisture resistance. CONSTITUTION:An electronic part element 2 is held inside a case 1, the top of which is opened, and the electronic part element 2 is buried by injecting injection resin A which does not include a flame retardant inside the case 1. Next, injection resin B high in fire retardancy is injected into the upper layer of the injected resin A and is hardened.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to electronic components. Specifically, it relates to a resin casting type electronic component in which an electronic component element is embedded in a casting resin.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view of a conventional resin casting type electronic component 11. This is case 1 with an open top
The casting resin C is filled in the inside, and the electronic component element 2 is embedded in the casting resin C. This casting resin C is a mixture of various inorganic fillers such as silica, aluminum hydroxide, magnesium silicate, calcium carbonate, and glass fiber in epoxy resin or the like in order to realize various required characteristics. .. In particular, a flame retardant is blended in order to enhance flame retardancy.

[0003]

However, in the electronic component as described above, after uncured casting resin is injected into the case and the electronic component element is immersed in the casting resin,
Before the casting resin is cured, the inorganic filler has a sediment of several tens of μm, and the upper layer portion of the casting resin is in a resin rich state. Therefore, in the upper layer part (exposed surface) of the casting resin, the filler deviates from the regular compounding amount, and various characteristics that can be achieved with the regular compounding amount are not satisfied, and especially high-voltage parts to which high voltage is applied. However, there is a problem that the flame retardancy required for the electronic components is deteriorated and the reliability of the electronic components is reduced.

Further, the inorganic filler compounded in the casting resin, especially the flame retardant compounded for the purpose of improving the flame retardancy in electronic parts, has a high unit price, which increases the cost of the casting resin and hence the electronic parts. It was the main factor. Furthermore, since the flame-retardant is mixed in the entire casting resin, there is a drawback that the electrical characteristics of the electronic parts, the moisture resistance, the adhesiveness between the element and the case, etc. are deteriorated.

The present invention has been made in view of the above-mentioned drawbacks of the conventional examples, and an object of the present invention is that the exposed layer of the casting resin has a high flame retardancy and, in addition, the inside of the casting resin. It is to provide a resin casting type electronic component having high electrical characteristics, adhesiveness between an element and a case, and moisture resistance.

[0006]

In the electronic component of the present invention, a flame-retardant case having an opening is filled with a first casting resin containing no flame retardant, and the first casting resin is filled with an electronic component. The component element is embedded, and the exposed surface of the first casting resin from the case is covered with the second casting resin having high flame retardancy.

[0007]

In the present invention, since the highly flame-retardant casting resin is used in the exposed portion of the casting resin cast in the flame-retardant case, it is not covered by the flame-retardant case. It is possible to improve the flame retardancy in the surface layer of the cast resin.

Further, since the first casting resin which is the casting resin inside does not contain the flame retardant, it is possible to enhance the electrical characteristics and moisture resistance of the electronic component element and the adhesiveness between the case and the element. it can.

Further, since the amount of the flame retardant used can be reduced by the above structure, the cost of electronic parts can be reduced.

[0010]

1 is a sectional view showing a resin casting type electronic component 4 according to an embodiment of the present invention. Describing along the manufacturing order, 1 is a box-shaped case with an open top,
It is formed of a material having high flame retardancy such as PBT. Reference numeral 2 denotes an electronic component element such as a high-voltage circuit element. The electronic component element 2 is held in the center of the case 1 by grasping the lead 3, for example. In this state, the casting resin A is injected into the case 1 until the electronic component element 2 is hidden, and the casting resin A is gelled. The casting resin A is a resin containing no flame retardant. Therefore, the casting resin A has excellent electrical characteristics, moisture resistance, and adhesiveness, and, for example, a resin mainly containing an epoxy resin and containing no flame retardant can be used. Then, another casting resin B is injected into the upper layer of the casting resin A in the case 1, and the casting resin A and the casting resin B are injected.
Heat cure. The casting resin B is a resin having high flame retardancy, and may be any compound for the purpose of improving flame retardancy. That is, it may be a resin whose main component is a flame-retardant resin, such as a phosphorus-based, bromine-based, or chlorine-based flame retardant (whether it is an addition type or a reaction type), an aluminum-based, antimony trioxide, etc. A resin containing the flame-retardant auxiliary agent may be used. For example, brominated epoxy resin or T
BBA (tetrabromobisphenol A) or the like can be used as the casting resin B.

In the electronic component 4, however, the electronic component element 2 is wrapped with the casting resin containing no flame retardant, so that the electronic component is excellent in electrical characteristics and moisture resistance, and thus the case 1 can be used. The adhesiveness with the electronic component element 2 is high. Moreover, since the electronic component 4 is covered from the outside by the highly flame-retardant case 1 and the highly flame-retardant casting resin B, it has high flame retardancy.

(Specific Examples) Next, the present invention will be described with reference to specific examples. First, as shown in the column of casting resin A in Table 1, bisphenol A type epoxy resin 10
To 0 parts by weight, 85 parts by weight of MeTHPA (methyltetrahydrophthalic anhydride) as a curing agent and 1 part by weight of imidazole, 220 parts by weight of silica fine powder as a modifier, and 1 part by weight of a defoaming agent were added, and a casting resin A was prepared. Also,
As shown in the column of casting resin B in Table 1, 35 parts by weight of MeTHPA, 1 part by weight of imidazole, and 0.5 parts by weight of a defoaming agent were added to 100 parts by weight of TBBA resin having high flame retardancy. B was prepared.

After delivering the electronic component element in the flame-retardant case, the casting resin A having the above composition was injected into the case and gelled under the conditions of 100 ° C. and 20 minutes. further,
Inject the casting resin B having the above composition onto the casting resin A, and
It was cured by heating at 0 ° C. for 2 hours.

(Conventional Example) For comparison, as shown in the column of the conventional example in Table 1, 70 parts by weight of bisphenol A type epoxy resin, 30 parts by weight of brominated epoxy resin as a flame retardant, and 75 parts by weight of MeTHPA as a curing agent. Parts and 1 part by weight of imidazole, 100 parts by weight of fine silica powder, 100 parts by weight of aluminum hydrate, 10 parts by weight of Sb ₂ O ₃ as a flame retardant, and 1 part by weight of a defoaming agent, and a cast resin according to a conventional example. Was prepared. Then, an electronic component element was cast-molded in the case using this cast resin.

[0015]

[Table 1]

(Characteristic Evaluation of Examples and Conventional Examples)
Using the samples of this example and the conventional example, flame retardancy (VL94V) in the upper part of the electronic component element, load failure rate in humidity and humidity (applying an AC voltage of 100V, 85 ° C., 95% RH
The number of failed samples when 20 samples were left for 3 months in the above environment was examined. Further, the cost reduction rate of the sample of the example was examined with the sample of the conventional example as a reference. The results are shown in Table 2.

[0017]

[Table 2]

However, as shown in Table 2, the electronic parts of the examples have superior flame retardancy and humidity / load failure rate in the upper layer, as compared with the electronic parts of the conventional example. Also, the cost could be reduced by 13% compared with the conventional product.

[0019]

According to the present invention, it is possible to improve the flame retardancy in the surface layer portion of the casting resin which is not covered with the flame retardant case, and the electrical characteristics of the electronic component element are provided inside the casting resin. It is possible to improve the moisture resistance and the adhesiveness between the case and the device.

Therefore, various characteristics such as flame retardancy of the electronic component can be improved, and the cost reduction effect is excellent.

[Brief description of drawings]

FIG. 1 is a sectional view of an electronic component according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional resin casting type electronic component.

[Explanation of symbols]

 1 Case 2 Electronic component element A Cast resin that does not contain flame retardant B Cast resin with high flame retardancy

Claims (1)

[Claims] 1. A flame-retardant case having an opening is filled with a first casting resin that does not contain a flame retardant, and an electronic component element is embedded in the first casting resin. An electronic component in which an exposed surface of a resin case is covered with a second casting resin having high flame retardancy.