JPH0334941Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] -Field of Industrial Application- The present invention relates to a watertight structure for electronic circuit components used underwater, such as underwater sensors.

- Conventional technology - For example, underwater equipment used for underwater sensors has an electronic circuit, and this electronic circuit is usually separated from the underwater sensor and attached to a ground station, but it transmits signals etc. over long distances via cables. This increases electrical loss, so it may be incorporated into an underwater sensor.

In such cases, there is a strong demand for miniaturization of the entire electronic circuit component as a watertight structure, and a watertight structure that can withstand long-term use underwater is also required.

FIG. 2 is a sectional view showing a watertight structure of a conventional electronic circuit component. In the figure, 1 is a metal container with an opening at the top, and 2 is a lid that fits into the opening and closes it. A concave groove 3 for a watertight dam is provided on the outer periphery of the side surface of this lid body 2, and a metal container 1 is placed inside this groove 3.
An O-ring 4 is attached to seal between the lid body 2 and the lid body 2. In order to obtain a reliable sealing effect, the material, shape, and dimensions of the O-ring 4 and the shape and dimensions of the groove 3,
Finishing and the like are detailed, for example, on pages 442 to 445 of the Mechanical Design Data Book published by Nikkan Kogyo Shimbun (June 30, 1972).

In addition, a stepped through hole 5 is provided in the center of the lid body 2.
A gasket 6 is press-fitted into the stepped portion of the through hole 5, and a retaining screw 7 for pressing the gasket 6 is screwed into the upper part of the through hole 5.
The gasket 6 and the holding screw 7 are provided with a through hole through which a signal line (to be described later) is passed.
The diameter of the through hole is slightly smaller than the outer diameter of the signal line.

8 is an electronic circuit component housed in the metal container 1; 9 is a signal line for signal extraction connected to the electronic circuit component 8; and is pulled out to the outside through the through hole of the cap screw 7.

In this way, in the conventional watertight structure, the metal container 1
The electronic circuit components 8 housed inside are kept watertight by an O-ring 4 and a gasket 6.

-Problems to be solved by the invention- However, according to the conventional watertight structure described above, it is necessary to change the thickness of the metal container depending on the depth of water used, and since the metal container is made of metal, it must be treated with anti-corrosion treatment. The problem is that it has to be done.

In addition, the structure is complex and tends to be large, making it difficult to handle.Moreover, as the signal wire becomes thinner, the signal wire rotates during the process of tightening the cap screw, resulting in damage to the signal wire. There was also the problem that watertightness inside the metal container could not be maintained.

The present invention aims to solve these problems.

[Structure of the idea]

-Means for Solving the Problems- In order to achieve the above-mentioned object, the present invention forms a flange with an L-shaped cross section at the opening on the top surface of a thin metal container, so that the inside of the metal container is An electronic circuit component that has been buffer-coated with a soft silicone resin in advance is stored, a signal line connected to the electronic circuit component is pulled out, and a low-shrinkage hard epoxy resin is injected into the metal container. A lid made of a thin metal plate is tightly bonded to the container, and the entire outer periphery of the metal container including the lid is covered with the same epoxy resin as described above.

-Function- According to this method, the electronic circuit components are buffer-coated with a soft silicone resin, and the inside and outside of the metal container is kept rigid with epoxy resin, so it is sufficient to withstand water pressure, etc. In addition to being durable, it is also possible to obtain waterproof properties and shielding effects for electronic circuit components.

-Example- Fig. 1 is a sectional view showing a watertight structure of an electronic circuit component according to the present invention. It has an opening and a flange 11 having an L-shaped cross section around the opening. This metal container 1
The material of 0 is selected in consideration of its excellent workability such as drawing, as well as corrosion resistance, adhesion, etc., and general-purpose materials such as aluminum alloys and brass plates can be used, for example.

Reference numeral 12 denotes a lid having the same shape as the opening of the metal container 10, which is made of a thin metal plate, and has a through hole 13 in the center thereof having approximately the same diameter as the outer diameter of the signal line 9.
have.

14 is a low shrinkage hard epoxy resin, 15 is a soft silicone resin, and the electronic circuit component 8 is buffer-coated with this silicone resin 15 in advance to prevent moisture and cast the low shrinkage hard epoxy resin 14. Consideration has been taken to alleviate subsequent curing shrinkage. 16 is an insulating seat.

Next, the assembly of this embodiment will be explained.

First, the electronic circuit component 8, which has been buffer-coated in advance with the soft silicone resin 15 as described above, is housed in the metal container 10, and the signal line 9 connected to the electronic circuit component 8 is pulled out to the outside. An insulating seat 16 is installed between the bottom of the metal container 10 and the electronic circuit component 8. Although this insulating seat 16 is not necessarily required, it is desirable to provide it when insulation is required between the metal container 10 and the electronic circuit component 8, or to prevent air bubbles from remaining during resin injection, which will be described later.

After doing this, a low shrinkage hard epoxy resin 14 is injected into the metal container 10. This resin injection is continued until it reaches the flange 1 of the metal container 10.

Next, the lid 12 is placed on the low-shrinkage hard epoxy resin 14 injected into the metal container 10, and its peripheral portion is tightly joined to the flange 11. At this time, the signal line 9 is passed through the through hole 13 provided in the lid 12, and the periphery of the through hole 13 is coated with the same silicone resin 15 as described above. This silicone resin 15 has the effect of preventing moisture from permeating underwater.

After the lid 12 is attached and coated with silicone resin 15, the entire outside of the metal container 10, including the lid 12, is integrally cast so as to be covered with the same low-shrinkage hard epoxy resin 14 as described above.

According to the watertight structure with the above configuration, the electronic circuit components housed in the metal container are buffer-coated with a soft silicone resin, and the inside and outside of the metal container is kept rigid with low-shrinkage hard epoxy resin. In addition to being able to sufficiently withstand compressive forces such as the above, it is possible to reliably waterproof and shield the electronic circuit component 8.

The reason why the metal container 10 is formed of a thin metal plate is because a thin metal plate can follow the contraction of the casting resin when it hardens, and the expansion and contraction stress caused by heat stress in the usage environment. Although it is desirable that the metal plate be thinner, a plate thickness of about 0.05 to 0.2 m/m was good in experiments due to pinholes in the metal plate, workability, etc.

Furthermore, when the metal container 10 is used in shallow water, a watertight structure can be obtained without injecting the casting resin, that is, the low-shrinkage hard epoxy resin 14 into the metal container 10. However, in this case, it is necessary to design the casting thickness of the resin around the outer periphery of the metal container 10 so that it can withstand water pressure. This will improve reliability.

Furthermore, in the above embodiment, if microballoons or fillers are added to the low-shrinkage hard epoxy resin 14, the curing shrinkage and linear expansion coefficient after casting can be reduced, and the compressive strength can be further improved. I can do it.

[Effect of idea]

As explained above, the present invention forms an L-shaped flange in cross section around the opening of a thin metal container, and the electronic circuit is pre-buffer-coated with silicone resin inside the metal container. After storing the parts and injecting a low-shrinkage hard epoxy resin into the metal container, a lid made of a thin metal plate is placed and joined to the flange, and the metal container including the lid is placed in the same manner as above. Since it has an integrated structure covered with epoxy resin, the following effects can be obtained. In other words, the electronic circuit components are buffer-coated with a soft silicone resin, and the inside and outer periphery of the container housing the electronic circuit components is covered with a hard, low-shrinkage epoxy resin. There is no need to change the water depth depending on the depth of water used, or to apply anti-corrosion treatment to the metal container, and there is no need to make the metal container itself a strong structure.

In addition, since the structure has a thin metal container embedded in the casting resin, it is possible to prevent moisture from permeating from the outside, and the structure is simple because it does not use conventional O-rings, gaskets, and retaining screws. It is possible to reduce the size of the device, improve ease of handling, and eliminate breakage of signal lines during assembly.

In addition, since the metal container is made of a thin metal plate, there is less thermal stress due to the difference in linear expansion coefficient with the casting resin, there is no problem such as peeling, and it is easy to assemble. It has many advantages, such as being highly reliable when used underwater and providing shielding effects for electronic circuit components.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a watertight structure of an electronic circuit component according to the present invention, and FIG. 2 is a sectional view showing a conventional watertight structure of an electronic circuit component. 8...Electronic circuit components, 9...Signal lines, 10...
Metal container, 11... flange, 12... lid, 13...
...Through hole, 14...Low shrinkage hard epoxy resin,
15...Silicone resin, 16...Insulating seat.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. Electronic circuit components that have been buffer-coated with a silicone resin are stored in a metal container that has a flange with an L-shaped cross section formed around the opening, and the metal After injecting a low-shrinkage hard epoxy resin into the container, a lid having the same shape as the opening is joined to the brim, and the entire outside of the metal container, including the lid, is made of the same low-shrinkage hard epoxy resin as above. A watertight structure for electronic circuit components characterized by being covered with epoxy resin. 2. The watertight structure of an electronic circuit component according to claim 1, which is characterized by using a low-shrinkage hard epoxy resin to which microballoons or fillers are added.