JPH01304701A - Electronic parts - Google Patents

Abstract

PURPOSE:To improve heat cycle resistance and humidity resistance by blocking open pores existent in a phenol resin layer with glass formed of silica or metal alcoxide containing, silica as a chief ingredient. CONSTITUTION:The title electronic parts have a basic sheathing structure comprising a phenol resin layer 4. Open pores 6 existent in the phenol resin layer 4 are blocked with glass 7 formed of silica or metal alcoxide having silica as a chief ingredient. In other words, the pores 6 existent in the phenol resin layer 4 are blocked with glass formed of metal alcoxide. Accordingly, parts elements are completely shielded from the atmosphere without permitting water and gas to invade into the parts. Further, since the basic sheathing structure comprises phenol resin, heat cycle resistance possessed by the phenol resin can be kept intactly. Hereby, highly practical electronic parts, which are excellent in heat cycle resistance and humidity resistance and has reduced deterioration in various characteristics even under conditions in need of very severe resistance to environment, can be yielded.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an electronic component with an improved exterior structure.

(Conventional technology) As an exterior material for electronic components, it is highly flexible and mass-producible.

Epoxy resins and phenolic resins are generally used from a cost standpoint.

However, when used as an exterior material for electronic components made of sintered ceramic elements, epoxy resin has a coefficient of linear expansion approximately two orders of magnitude larger than that of ceramic elements, so
Cracks occur in the exterior material due to the impact. Therefore, it is difficult to satisfy the thermal cycle characteristics between -50° C. and +150° C. required for electronic parts for automobiles. On the other hand, phenolic resin contains a large amount of inorganic fillers such as S i 02 and CaCO3 in order to approximate the linear thermal expansion coefficient of ceramic. Therefore, it has very good heat cycle resistance, but because the structure is essentially porous, there is a problem that the ceramic element deteriorates during use due to the intrusion of moisture and gas, leading to failure.

In order to eliminate this drawback, impregnation with molten wax, liquid epoxy resin, or liquid silicone resin has conventionally been carried out.

However, in-vehicle electronic components tend to require very strict Y:J resistance, and are required to have not only heat cycle resistance but also excellent moisture resistance.

For example, it is necessary to ensure the electrical, structural, and appearance characteristics in a brake test at 121°C, 2 atmospheres, and 95% RH.

In response to the demand for exterior materials that have both high heat cycle resistance and high moisture resistance, it is difficult to guarantee high heat cycle resistance with epoxy resins, and with phenolic resins, it is difficult to guarantee high heat cycle resistance under high temperature and high humidity conditions. It is difficult to maintain moisture resistance at V5.

This is because wax and silicone soften when exposed to high temperatures.
As it melts, it is no longer possible to maintain a completely filled structure of impregnated material. Additionally, when impregnating with liquid epoxy, if the impregnation is complete, there is a risk of micro-cranking occurring during the heat cycle due to the difference in expansion coefficient between the epoxy resin and the phenol resin, and there are other problems such as not being able to guarantee moisture resistance. I was holding on to something.

(Problems to be Solved by the Invention) As described above, conventional electronic components having a film exterior structure cannot simultaneously satisfy both heat cycle resistance and moisture resistance, and are therefore not effective. Countermeasures were desired.

The present invention has been made in view of the above points, and an object of the present invention is to provide an electronic component that has excellent heat cycle resistance and moisture resistance, and has an exterior structure that eliminates the causes of characteristic deterioration during use. be.

[Structure of the Invention] (Means for Solving the Problems) The electronic component according to the present invention has a basic exterior structure consisting of a phenolic resin layer, and the continuous pores present in the phenolic resin layer are filled with silica or silica as a main component. It is characterized by being closed with glass produced from a metal alkoxide.

(Function) According to the above configuration, the pores existing in the phenolic resin layer are blocked by the glassy substance produced from the metal alkoxide, so the component body and the outside air are completely cut off, and moisture is not allowed to enter the inside. In addition, since the basic exterior is made of phenolic resin, the heat cycle resistance of phenolic resin can be maintained, and since the glass material is mainly composed of silica, it has excellent chemical resistance. Becomes excellent in sex.

(Example) An example of the present invention will be described below by exemplifying a varistor. That is, as shown in Fig. 1, a ceramic powder made of zinc oxide as a main component and mixed with several other metal oxides is molded and sintered into a disc shape with a diameter of 20 am and a thickness of 1.0 mm. After forming an electrode 2 with a diameter of 18#, leaving the outer periphery on both sides of the varistor body 1, and attaching a lead wire 3 to this electrode 2, S! 60 to 70 wt% of inorganic filler whose main component is 02, 5 to 10 wt% of resin, and 20 to 30 wt% of solvent.

Contains 10 to 20 wt% of pigment and other components, and has a viscosity of 10 to 1
The varistor body 1 is placed in a phenol resin liquid adjusted to 5 voids to form a phenol resin layer 4 as an exterior.

The coating conditions in the process of forming the phenolic resin layer 4 were as follows: After the first depth raising, room temperature drying was performed for 2 minutes;
After drying the solvent component, a second coating is performed to obtain a predetermined thickness. After that, it was left to dry at room temperature for 16 hours, and finally it was heated and cured at 150°C for 30 minutes, and the phenolic resin F? 14 will be completed.

Next, the phenolic resin layer 4 was immersed for 5 minutes in silica or a metal alkoxide glass solution containing silica as a main component and aluminum, iron, silicon, etc. adjusted to a viscosity of 70 centimeters, and then pulled out and left at room temperature for 30 minutes. After drying for a minute, heating was performed at 150° C. for 30 minutes to form a glass film 5 on the phenol resin layer 4.

According to the varistor with the exterior structure configured as above,
As shown in FIG. 2, a glass film 5 is formed in continuous pores 6 existing in the phenolic resin layer 4.
The pores 6 are closed, the varistor element 1 is completely isolated from the outside air, and no moisture or gas can enter the varistor element 1, resulting in excellent moisture resistance.

In addition, the basic exterior structure of the above varistor is a phenolic resin layer 4, which, combined with the excellent heat cycle resistance of phenolic resin, allows it to be used under conditions that require very severe environmental resistance, such as in automobiles. It has the advantage of no deterioration in opening performance.

Next, specific effects of the present invention will be explained based on experimental results.

That is, the present invention (A) described in the above embodiment, the conventional example (B) with a powdered epoxy resin exterior, the conventional example (C) with an epoxy resin-impregnated phenolic resin exterior, and the conventional example with a wax-impregnated phenolic resin exterior. The heat cycle resistance test (exterior peeling failure vs. number of heat cycles) and pressure traction test (voltage change rate vs. time) were conducted on each conventional example (D) varistor, and the results are shown in Figures 4 and 5. It was J3ri.

Note that the heat cycle test was conducted at -50°C.

One cycle was performed at +150°C for 50 minutes each, and the pressure test was performed at 123°C and 2 atm.

The test was carried out under conditions of 95% RH.

As is clear from FIGS. 4 and 5, although the conventional example (B) has excellent moisture resistance, its heat cycle resistance is poor at the I4i end. In the conventional example (C), more cracks occur after the number of heat cycles exceeds 200, and the voltage change rate increases as time passes.

Further, although the conventional example (D) has excellent heat cycle resistance, it has poor moisture resistance.

On the other hand, it can be seen that the present invention (A) has the effect of combining excellent heat cycle resistance and moisture resistance.

In the above embodiment, the glass film 5 was formed in the continuous pores 6 existing in the phenol resin layer 4. A structure may be obtained in which the pores 6 existing in the phenol resin layer 4 are completely filled with glass 7 by repeating the process several times, as shown in FIG.

Further, in the above embodiments, a varistor has been described as an example, but it goes without saying that the present invention can be applied to other electronic components, such as ceramic capacitors, solid electrolytic capacitors made of sintered elements, and alumina substrates.

[Effect of the invention 1] According to the present invention, an electronic device with high practical value that does not deteriorate in opening performance even when used under conditions that require very severe environmental resistance due to fluctuations in heat cycle resistance and moisture resistance. parts can be obtained.

[Brief explanation of the drawing]

1 and 2 relate to an embodiment of the present invention, in which FIG. 1 is a partially cutaway front view showing a varistor, FIG. 2 is an enlarged view of part A in FIG. 1, and FIG. FIG. 4 is an enlarged view of another embodiment corresponding to part A, FIG. 4 is a heat cycle number-cumulative failure rate curve diagram, and FIG. 5 is a time-voltage change rate characteristic curve diagram. 1... Varistor cord body 2... Electrode 3... Lead wire 4... Phenol resin layer 5... Glass membrane 6... ...Pore 7...Glass patent application Hitomarun Electronics Co., Ltd. Partially cutaway cross-sectional front view of varistor Enlarged view of part A of other embodiments Figure 3 Number of heat cycles (times) 4 Figure R (il) Figure 5

Claims (1)

[Claims] An electronic component characterized in that its basic exterior structure consists of a phenolic resin layer, and continuous pores existing in the phenolic resin layer are closed with glass produced from silica or a metal alkoxide containing silica as a main component.