JPH0613832A - Electronic component sealing structure - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a sealing structure for electronic components capable of ensuring the sealing property even when the characteristic of the sealing agent is deteriorated due to environmental changes or a temperature higher than the heat resistance limit is erroneously applied. [Structure] An electronic component element is housed in a case, and an opening of the case is sealed with a sealant. The sealant has a multi-layer structure,
A heat-resistant sealant is used for the outermost layer and the innermost layer, and a sealant having meltability at high temperature and hardening at room temperature and adhesiveness is used for the intermediate layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic part sealing structure, and more particularly to an electronic part sealing structure in which an electronic part element is housed in a case and an opening of the case is sealed with a sealant.

[0002]

2. Description of the Related Art Conventionally, in a piezoelectric resonator, a resonator element and a plurality of terminal plates in contact with both side surfaces of the element are housed in a bottomed box-shaped case, and the lead portions of the terminal plate are placed outside the case. It is proposed that the opening of the case is sealed with a sealant in the derived state (Japanese Utility Model Publication No. 4-46720).

[0003]

The above-mentioned sealing agent is
Epoxy resins are widely used because they have high heat resistance and ensure the adhesion of the sealing portion even after soldering. However, in reality, due to deterioration of the characteristics of the encapsulant due to environmental changes, and thermal stress when a temperature above the heat resistance limit is mistakenly applied during soldering, a gap is created in the encapsulation part, resulting in poor sealing performance. It was sometimes lowered. Therefore, it is an object of the present invention to provide a sealing structure for an electronic component, which can ensure the sealing performance even when the characteristics of the sealing agent are deteriorated due to environmental changes or a temperature above the heat resistance limit is erroneously applied.

[0004]

In order to achieve the above object, the sealing structure of the present invention has a multi-layer structure of a sealant, a heat-resistant sealant is used for the outermost layer, and the inner layer has a predetermined temperature. As described above, a sealing agent having a melting property and curing at room temperature and having an adhesive property is used. The temperature at which the inner sealant has meltability may be set, for example, near the solder melting temperature (180 ° C. to 360 ° C.), or when the outer sealant is a thermosetting resin, the temperature may be higher than the curing temperature. You may set it. In any case, various settings can be made according to the purpose of use.

[0005]

In the case where the sealant has a two-layer structure, the same heat-resistant sealant as before is used for the outer layer, and the inner layer melts at high temperature and has adhesiveness at room temperature. A sealant is used. As a result, when a temperature higher than the heat resistance limit is applied to soldering or the like, the sealant in the inner layer is brought into a molten state and enters the gap formed between the case and the outer sealant to ensure the hermeticity. When cooled from this state, the inner sealant cures, but since it has adhesiveness at room temperature, the hermeticity is maintained. The inner sealant remains in a molten state when it is exposed to a high temperature again.

[0006]

1 and 2 show a piezoelectric resonator as an example of the present invention. The case 1 is injection-molded with a heat-resistant resin such as polyphenylene sulfide in the shape of a box with a bottom, and an opening 1a is provided at one end thereof. The resonator element 2 is housed inside the case 1. Resonator element 2
Is a piezoelectric substrate 2a made of square piezoelectric ceramics or the like.
The electrodes 2b and 2c are provided on both main surfaces of, for example, a ceramic resonator using a spreading vibration mode.

The terminal plates 3 and 4 are made of a conductive metal plate having a spring property, and are inserted between both main surfaces of the resonator element 2 and the inner wall of the case 1. The resonator element 2 is provided on the terminal plates 3 and 4.
Contact portions 3a and 4a that are in pressure contact with the electrodes 2b and 2c, respectively,
External connection portion 3 protruding outside from the opening 1a of the case 1
b and 4b are formed. The contact portions 3a and 4a are curved so as to be elastically deformable in the plate thickness direction.

A paper base 5 is provided in the opening 1a of the case 1.
Are fitted, and the opening 1a is almost closed. The base 5 is previously formed with a slit 5a into which the external connection portions 3b and 4b of the terminal plates 3 and 4 can be inserted. Then, the sealants 6 to 8 are placed in the recess formed by the opening 1a and the base 5.
Are injected in three layers to seal the opening 1a. The base 5 has a function of preventing the sealants 6 to 8 from flowing into the case 1 and positioning the terminal plates 3 and 4. As the sealants 6 and 8 for the outermost layer and the innermost layer, a resin having a heat resistance at least equal to or higher than the melting temperature of the solder is used, such as epoxy resin or UV curing resin. Further, as the encapsulant 7 for the intermediate layer, a resin material such as a thermoplastic which has a melting property at a high temperature such as a solder melting temperature and which hardens at a normal temperature and has an adhesive property is used. The sealants 6 and 8 for the outermost layer and the innermost layer may be the same material or different materials.

The above-mentioned piezoelectric resonator is manufactured in the following order. First, the resonator element 2 and the terminal plates 3 and 4 are inserted into the case 1, and then the base 5 is fitted into the opening 1a. Next, the innermost layer sealant 8 is injected into the bottom of the recess formed by the opening 1a and the base 5. At the time of injection, the sealant 8 is in a liquid state, but due to the base 5, the case 1
It can be prevented from flowing into the inside. After the sealant 8 is injected, the sealant 8 is cured by heating to a predetermined temperature or irradiating with ultraviolet rays. Next, the sealant 7 of the intermediate layer is injected so as to overlap the sealant 8. The sealant 7 is heated to a molten state, poured onto the sealant 8, and then cooled and cured. Then, the outermost sealant 6 is injected onto the sealant 7. The sealant 6 is injected in a liquid state like the innermost layer sealant 8 and then heated to a predetermined temperature or irradiated with ultraviolet rays to cure the sealant 6 and complete the sealing.

In the encapsulation step, when the outermost layer encapsulant 6 is heated to cure, the temperature may cause the intermediate layer encapsulant 7 to melt.
If the melting temperature of the encapsulant 7 is set higher than the curing temperature of, the encapsulant 7 will not flow. When a UV curable resin is used as the outermost layer sealant 6, there is no need to heat it for curing, so there is no risk of the intermediate layer sealant 7 melting.

In the piezoelectric resonator having the above structure, if the characteristics of the sealing agents 6 and 8 are deteriorated due to environmental changes, the sealing performance of the sealing portion may deteriorate. However, since the sealant 7 of the intermediate layer has adhesiveness at room temperature, it is between the sealants 6 and 8 and the case 1 or between the sealants 6 and 8 and the terminal boards 3 and 4. Even if a gap is created, the sealing performance is not impaired. In addition, even if a temperature higher than the heat resistance limit is mistakenly applied at the time of soldering, the sealants 6 and 8 and the case 1 are caused by thermal stress.
There may be a gap between the sealant 7 and the terminal plates 3 and 4, but since the sealant 7 of the intermediate layer melts and enters the gap, the hermeticity can be secured. When cooled to room temperature, the encapsulant 7 of the intermediate layer is hardened in the gap and adheres without any gap.

FIG. 3 shows a second embodiment of the present invention, which is applied to an electronic component similar to that of the first embodiment. In the figure, 10 is a resin case, 11 is a paper base, 12 is a terminal, 13 is an outermost layer sealant, and 14 is an inner layer sealant. The outermost layer encapsulant 13 is a heat-resistant epoxy resin or UV curable resin, and the inner layer encapsulant 14 melts at a high temperature and hardens at a normal temperature to be an adhesive thermoplastic resin. Resin material. As a method of forming the inner layer (sealant 14), in addition to the method of injecting it into the case 10 in a molten state, the sealant 1 is previously applied to the base 11.
4 may be applied or attached to be integrated. In the case of this embodiment as well, similar to the first embodiment, the degree of sealing can be maintained regardless of the operating temperature and deterioration over time.

FIG. 4 shows a third embodiment of the present invention. In this embodiment, a step surface 20a is formed in the opening of the first case 20, and the peripheral edge of the second case 21 that closes the opening is placed on the step surface 20a. Then, in the gap between the case 20 and the case 21, three-layer structure sealing agents 22 to 2 are formed.
4 is provided to seal the inside of the cases 20 and 21. In the case of this embodiment, a heat-resistant epoxy-based or UV-curable adhesive is used as the outermost and innermost sealing agents 22 and 24, and a meltable adhesive that melts at high temperature as the intermediate layer sealing agent 23. The agent is used. The outermost and innermost sealants 22 and 24 may be different materials. in this case,
Even if there is a gap between the sealing agents 22 to 24 of each layer, the sealing performance will not be affected.

As described above, the present invention is not limited to one in which the entire opening of the case is sealed with a sealant, but a lid, a terminal block, or the like is fitted in the opening of the case, and the case and the lid or the terminal block are fitted together. It can also be applied to a structure in which a sealant is injected into a gap between the two and a structure in which a sealant is injected into a mating surface of a case having a two-part structure.
Further, the case is not limited to the resin case, and a metal case or other material may be used.

In the case of the present invention, if the operating temperature is clear, conversely, the structure of the present invention can be used to improve the hermeticity of an electronic component having insufficient initial hermeticity after soldering. Is. In other words, even if there is a gap in the sealing portion at the initial stage of forming the sealing portion, the fusible sealant is then melted and enters the gap by heating by soldering or the like, so that the sealing performance is improved. be able to.

[0016]

As is apparent from the above description, according to the present invention, a sealant having excellent heat resistance is used for the outermost layer, and the inner layer is meltable at high temperature and hardened at room temperature for adhesion. Since a sealant with good properties is used, even if the characteristics of the sealant deteriorate due to environmental changes, or if a temperature above the heat resistance limit is mistakenly applied during soldering, no gap will be created in the sealant, and the sealability will be improved. There is a feature that can secure.

[Brief description of drawings]

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

FIG. 2 is a partially enlarged view of the electronic component shown in FIG.

FIG. 3 is a partially enlarged sectional view of a second embodiment of the present invention.

FIG. 4 is a partially enlarged sectional view of a third embodiment of the present invention.

[Explanation of symbols]

 1 Case 1a Opening 2 Resonator element 6,8 Heat resistant sealant 7 Melt sealant

Claims (1)

[Claims] 1. An electronic component in which an electronic component element is housed in a case and an opening of the case is sealed with a sealant, wherein the sealant has a multi-layer structure, and a heat-resistant sealant is used as an outermost layer. An encapsulating structure for electronic parts, characterized in that a sealing agent having a melting property at a predetermined temperature or higher and curing at room temperature and having an adhesive property is used for the inner layer.