JPH04302197A - Electronic component - Google Patents

Abstract

PURPOSE:To enhance an electronic component in reliability of resistance to vibration, shock, and heat by a method wherein a sheet material small, in friction coefficient and high in tensile strength is interposed between an inner housing and a heat insulator. CONSTITUTION:A spongy cushion material 11 is filled into the base of a recess hollowed at the center of a lower heat insulator 5a, and a surface film 11a high in tensile strength in a direction where inner thermal expansion is large is provided to the contact surface of the cushion material 11 with the heat insulator 5a. When an inner housing 2 is inserted into the recess provided to the lower heat insulator 5a, a first sheet 12a low in friction resistance and high in tensile strength is wound on the peripheral surface of the housing 2. After the insertion of the housing 2, when an upper insulator 5b is mounted thereon, a second sheet 12b formed of the same material with the first sheet 12a and into the same shape with the upper insulator 5b is interposed between the upper and the lower insulator, 5b and 5a. By this setup, an electronic component can be improved in reliability of resistance to vibration, shock, and heat.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to electronic components used in environments subject to severe vibrations, shocks, and temperature changes.

0002

2. Description of the Related Art Electronic components used in environments with severe vibrations, shocks, and temperature changes, such as solid identification devices used in automobile production lines, are equipped with electronic circuit boards shown in FIG. 5 to protect them from the environment. It is configured as shown in .

In FIG. 5, 1 is an electronic circuit board. Various circuit elements are mounted on this substrate 1. As shown in FIG. 6 or 7, the electronic circuit board 1 is stored horizontally or vertically in an internal storage case 2 with one side open, and is fixed by filling the case 2 with silicone resin 3. do.

On the other hand, a heat-resistant resin case body 4a serving as an exterior
A lower heat insulating material 5a formed by compression molding of anhydrous silica powder is placed inside, and the center of the heat insulating material 5a is hollowed out to form a hole in which the internal storage case 2 is housed. After filling the bottom of this hole with a sponge-like cushioning material 6 and accommodating the internal storage case 2, the upper heat insulating material 5b is further inserted, and the case lid 4b is screwed onto the case body 4a and bonded. The cushion material 6 is foamed and has enough softness to moderate the amount of expansion of the internal storage case 2.

A small diameter hole 4c is formed in the case lid 4b, through which gas is vented, resin particles 7 are stuffed into the hole 4c, and an adhesive 8 is poured and hardened. By closing the hole 4c in this manner, the inside of the case 4 is kept in a reduced pressure state, and expansion or expansion and contraction due to heat is reduced. However, in the conventional electronic component with the above configuration,
It has the following problems.

First, since the heat insulating materials 5a and 5b are made by compression molding powder, they are extremely brittle, and if subjected to vibration or shock over a long period of time, they will break due to the friction generated between them and the internal storage case 2. It's starting to crumble. As a result, the hole that houses the internal storage case 2 widens, reducing the heat insulation effect and the function of fixing the case.

Second, if the heat insulating materials 5a and 5b collapse, the internal storage case 2 may vibrate in the lateral direction, causing friction, and the crushed powder may enter the sponge-like cushion material 6, resulting in damage to the cushion. The material 6 is torn due to long-term use, and its vibration and shock mitigation function deteriorates.

Thirdly, the internal storage case 2 has a heat insulating material 5a,
Although it is insulated by 5b, the temperature still rises in a high-temperature environment. On the other hand, since the silicone resin 3 filled in the case 2 has a large coefficient of thermal expansion, it expands as the temperature rises and protrudes from the case 2 as shown by the two-dot chain line in FIG. 6 or FIG. In this case, the bulge is large at the center and small at the periphery. Therefore, when the substrate 1 is fixed in a horizontal state, stress is applied to the central portion of the substrate 1 as shown by the arrow in FIG. 6, and there is a high possibility that wire breakage or solder cracks will occur. In addition, when the board is fixed in a vertical position, as shown by the arrow in FIG.
Stress will be applied to the circuit elements above, and there is a high possibility that solder cracks or element destruction will occur.

Fourthly, when closing the gas vent hole 4c formed in the case lid 4b, the adhesive 8 is poured after filling the resin particles 5, but the hole 4c is filled with resin particles. It is often not completely blocked by grains 7. In this case, since the adhesive 8 flows into the case 4 through the gap, it is very difficult to cure the adhesive 8 while it is stored in the hole 4c.

In particular, if this airtight sealing is performed after the case 4 has been warmed and gas has been vented from the inside, the pressure inside the case 4 will become reduced as the case 4 cools, so that the adhesive 8 will penetrate even further inside. It will flow in. Since the adhesive 8 is cured in this state, the reliability of the hermetic seal is low.

Furthermore, in order to vent the internal gas and maintain a reduced pressure state at room temperature, it is necessary to airtightly seal the case 4 with adhesive 8 before the temperature of the case 4 cools down.
Since the bonding work was carried out in a short time while the temperature of case 4 was high, the danger to the workers was also high.

0012

[Problems to be Solved by the Invention] As stated above, conventional electronic components used in environments with severe vibrations, shocks, and temperature changes have low reliability in terms of vibration, shock, and heat resistance during long-term use. Moreover, the incompleteness of the hermetic sealing process,
The problem was that it was highly dangerous.

The present invention was made to solve the above problems, and its first purpose is to provide an electronic component that is highly reliable in terms of vibration, shock, and heat resistance during long-term use. The second objective is to provide an electronic component in which the hermetic sealing process is less incomplete and less dangerous.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the present invention is used in an environment with severe vibrations, shocks, and temperature changes, and an electronic circuit board is housed in an internal storage case, and this is placed in a heat-resistant resin case. In the electronic component which is housed in the electronic component and has a heat insulating material interposed between the inner storage case and the heat-resistant resin case, the inner storage case and the heat insulating material have a low coefficient of friction property and a high tensile strength. The first feature is that a tall sheet-like thin material is interposed. A second feature is that the contact surface of the heat insulating material with the internal storage case is coated.

[0015] A cushioning material is provided between the bottom surface of the internal storage case and the heat insulating material and formed with a skin having high tensile strength in the direction of large internal thermal expansion on at least the contact surface with the heat insulating material. is the third feature. A fourth feature is that the electronic circuit board is placed in the internal storage case in a direction other than horizontally or vertically, and then filled with resin and fixed.

[0016] Counterbore forming means for forming a counterbore of a specific depth in the airtight sealing hole formed in the heat-resistant resin case; A fifth feature is that the adhesive is provided with an elastic gasket having substantially the same shape as the bottom, and an adhesive is poured onto the gasket and cured. A sixth feature is that a collar is formed around the internal storage case.

[0017]

[Operation] In the first feature, the friction between the internal storage case and the heat insulating material is reduced by a sheet-like thin material that has a low coefficient of friction and high tensile strength. and suppress the collapse of the insulation material. In the second feature, the contact surface of the heat insulating material with the internal storage case is coated to reduce friction therebetween and suppress collapse of the heat insulating material.

[0018] In the third characteristic configuration, the cushioning material interposed between the bottom surface of the internal storage case and the heat insulating material,
A skin with high tensile strength is formed in the direction of greater internal thermal expansion at least on the contact surface with the heat insulating material to prevent powder from entering the cushioning material due to collapse of the heat insulating material.

In the fourth feature, the electronic circuit board is placed in the internal storage case in a direction other than horizontally or vertically, that is, at an angle, thereby reducing the stress applied to the board and circuit elements due to thermal expansion of the filled resin. reduce

[0020] In the fifth feature, the gasket placed at the bottom of the counterbore prevents the adhesive from flowing into the case, improves workability, and facilitates bonding when the case temperature is high. Reduce work hazards.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. However, in FIG. 1, the same parts as in FIG. 5 are denoted by the same reference numerals, and the different parts will be mainly explained here.

FIG. 1 shows its structure, and the bottom of a hole formed by hollowing out the center of the lower heat insulating material 5a is filled with a sponge-like cushioning material 11. This cushioning material 11 has a skin 11a having high tensile strength in the direction of large internal thermal expansion on the surface in contact with the heat insulating material 5a. As the skin 11a, a relatively smooth thin sheet may be applied, or the surface of the cushion material 11 itself may be heat-treated to make it smooth.

According to the above structure, since the contact surface of the cushion material 11 with the heat insulating material 5a has a skin having high tensile strength in the direction of large internal thermal expansion, it is strong against friction with the internal storage case 2 and the heat insulating material Powder due to the collapse of 5a cannot enter the cushion material 11. Therefore, even when the electronic component is used for a long period of time, it can sufficiently maintain its function as a cushion and contribute to improved reliability.

Next, when inserting the internal storage case 2 into the hole of the lower heat insulating material 5a, the first sheet 12a having a low coefficient of friction and high tensile strength is wrapped around the circumferential surface of the case 2. I'll keep it. Examples of the material for the sheet 12a include tetrafluoroethylene. After inserting the case 2, the upper heat insulating material 5b is further placed, but at this time, the first sheet 1
A second sheet 12b made of the same material as 2a and having the same cross-sectional shape as the upper heat insulating material 5b is interposed.

According to the above configuration, the first sheet 12a eliminates friction between the internal storage case 2 and the lower heat insulating material 5a, and the second sheet 12b eliminates the friction between the internal storage case 2 and the lower heat insulating material 5a.
Friction between the upper heat insulating material 5b and the upper heat insulating material 5b is eliminated. Since the first and second sheets 12a and 12b both have low coefficient of friction characteristics, the friction generated between them and the insulation materials 5a and 5b is extremely low, reducing the collapse of the insulation materials 5a and 5b during long-term use. can do. Moreover, since the tensile strength is high, the sheet itself will not be torn even if some friction occurs.

Therefore, even if the heat insulating materials 5a and 5b are made by compression molding powder and are subjected to vibrations and shocks over a long period of time, the friction generated on their surfaces is extremely small, reducing the possibility of deformation. This allows the hole portion housing the internal storage case 2 to be prevented from expanding, thereby maintaining the heat insulating effect and the function of fixing the case.

Here, as shown in an enlarged view in FIG. 2, the electronic circuit board 1 to be placed in the internal storage case 2 is placed in the direction in which the amount of thermal expansion of the resin 3 to be filled later is maximum (direction of arrow a in the figure). Store it diagonally, neither horizontally nor vertically.

According to the above structure, even if the filled resin 3 expands as shown by the two-dot chain line in the figure due to use in a high temperature range, for example, the circuit board 1 remains horizontal with respect to the direction a in which the expansion is maximum. Therefore, the load F directly applied to the mounting element can be reduced. Also, since it is not vertical, the entire load F due to resin expansion does not act on the board, but only the component Fv perpendicular to the board 1 acts on it, as shown in FIG. The amount of deflection will never reach its maximum. Therefore, with the above configuration, stress acting on the circuit board 1, the mounted elements on the board, and the solder for attaching the elements can be alleviated.

Furthermore, as shown in an enlarged view in FIG. 3, the case lid 4b is formed with a small-diameter gas vent hole 4c, and then a counterbore 4d with a specific depth is formed. After warming the entire case 4 and venting gas from the hole 4c, counterbore 4d
A gasket 1 having elasticity and having almost the same shape as the bottom of the
3 is inserted into the bottom of the counterbore 4d, and the adhesive 8 is poured onto it and cured.

The gasket 13 may be made of silicone rubber, for example. The adhesive 8 used is, for example, an epoxy resin adhesive that has a good grip with the case 4 and can maintain airtightness. The counterbore 4d is the gasket 13
It has an appropriate depth to accommodate the adhesive 8, and the wall surface may be tapered.

According to the above structure, the gasket 13 inserted into the counterbore 4d can maintain complete airtightness on the wall and bottom surfaces of the counterbore, so even if the adhesive 8 is poured thereon, the case remains intact. The adhesive 8 does not flow into the inside of the adhesive 4. In particular, when the case 4 is warmed and the gas inside is vented, as the case 4 cools down, the pressure inside the case 4 becomes reduced, so that a force that is sucked into the case acts on the gasket 13. For this reason, it comes to stick even more to the bottom surface of the counterbore 4d, and airtightness can be improved.

Furthermore, even when the adhesive 8 is poured into the case 4 under reduced pressure, the airtightness is maintained by the gasket 13, so performing the gluing work within the holding period ensures that the adhesive 8 is poured into the case 4. Airtightness can be maintained. Further, after confirming the airtight state, the process of curing the adhesive 8 can be started, and the bonding work can be carried out with sufficient time. Thereby, danger in the bonding work process can be avoided and a highly reliable hermetic sealing structure can be obtained.

[0033] Regarding the above embodiment, the gasket 13
Immediately after insertion, the adhesive 8 was poured into the case and left for several hours, but the adhesive 6 did not flow into the case, confirming that the airtight state was maintained.

Conventionally, in order to reduce the amount of expansion of the internal storage case 2, a cushioning material is inserted into the bottom of the hole in the lower heat insulating material 5a. However, because of this cushioning material, the case 2 moves internally when subjected to vibration, and the lower and upper insulating materials 5a,
Friction is generated between the heat insulators 5a and 5b, and the heat insulating materials 5a and 5b become deformed when used for a long time.

In the above embodiment, the friction was reduced by improving the cushioning material and inserting the sheet to suppress the collapse of the heat insulating materials 5a and 5b. By suppressing the movement of the case 2, friction can be actively reduced. In FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the explanation thereof will be omitted.

That is, in the embodiment shown in FIG. 4, a collar 2a is formed at the upper edge of the internal storage case 2. As shown in FIG. on the other hand,
The hole in the lower heat insulating material 5a is formed so that its depth is equal to the height from the bottom of the case 2 to the collar 2a. Regarding the case 2, after a substrate (not shown) is fixed by being filled with silicone resin 3, a cushioning material 14 is placed thereon to reduce the amount of thermal expansion of the resin 3. The case 2 configured as described above is inserted into the hole of the lower heat insulating material 5a, the upper heat insulating material 5b is placed thereon, and the case lid 4b is attached to the case body 4a.

According to the above structure, the brim 2a of the case 2 is sandwiched between the lower and upper insulating materials 5a and 5b, so that it is firmly fixed, and since there is no cushioning material at the bottom,
It does not move within the hole even if vibration is applied. Therefore, no friction occurs between the case 2 and the heat insulating materials 5a, 5b, and it is possible to prevent the heat insulating materials 5a, 5b from collapsing. Further, the dimensional increase caused by the expansion of the substrate storage portion of the case 2 due to a rise in temperature is absorbed by inserting the cushion material 14 in the upper part, and there is no performance deterioration in terms of thermal characteristics. In the above embodiment, it goes without saying that it will be even more effective if the improvement of the cushioning material and the sheet insertion shown in the embodiment of FIG. 1 are used together.

[0038]

[Effects of the Invention] As described above, the present invention provides an electronic component that is highly reliable in terms of vibration resistance, shock resistance, and heat resistance during long-term use, is completely airtightly sealed, and has low operational risks. I can do that.

[Brief explanation of the drawing]

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

FIG. 2 is an enlarged sectional view showing the inside of the internal storage case of the same embodiment.

FIG. 3 is a sectional view showing the electronic circuit board of FIG. 2 in a state where it is housed in a case.

FIG. 4 is a sectional view showing another embodiment of the invention.

FIG. 5 is a cross-sectional view showing the structure of a conventional electronic component.

FIG. 6 is a cross-sectional view showing the electronic circuit board in FIG. 5 in a state where it is housed in a case.

FIG. 7 is a cross-sectional view showing another state of the electronic circuit board in FIG. 5 stored in the case.

[Explanation of symbols]

1...Electronic circuit board, 2...Internal storage case, 2a...Brim,
3...Silicone resin, 4...Heat-resistant resin case, 4a...Case body, 4b...Case lid, 4c...Gassing hole, 4d...Spot face, 5a...Lower insulation material, 5b...Upper insulation material, 6, 11
, 14...Cushion material, 7...Resin particles, 8...Adhesive, 1
1a...Skin, 12a, 12b...Sheet, 13...Gasket.

Claims (7)

[Claims] Claim 1: Used in an environment with severe vibrations, shocks, and temperature changes, an electronic circuit board is housed in an internal housing case, this is housed in a heat-resistant resin case, and an electronic circuit board is placed between the internal housing case and the heat-resistant resin case. An electronic component having a heat insulating material interposed therebetween, characterized in that a thin sheet material having a low coefficient of friction and high tensile strength is interposed between the internal storage case and the heat insulating material. and electronic components. 2. The electronic component according to claim 1, wherein the material is tetrafluoroethylene. 3. Used in an environment with severe vibrations, shocks, and temperature changes, the electronic circuit board is housed in an internal housing case, this is housed in a heat-resistant resin case, and the circuit board is placed between the internal housing case and the heat-resistant resin case. An electronic component having a heat insulating material interposed therebetween, characterized in that a surface of the heat insulating material in contact with the internal storage case is coated. 4. Used in an environment with severe vibrations, shocks, and temperature changes, the electronic circuit board is housed in an internal housing case, this is housed in a heat-resistant resin case, and the electronic circuit board is placed between the internal housing case and the heat-resistant resin case. In the electronic component having a heat insulating material interposed therebetween, a skin having high tensile strength in a direction of large internal thermal expansion is formed between the bottom surface of the internal storage case and the heat insulating material, and at least on the contact surface with the heat insulating material. An electronic component equipped with a cushioning material. 5. Used in an environment with severe vibrations, shocks, and temperature changes, the electronic circuit board is housed in an internal storage case, this is housed in a heat-resistant resin case, and the electronic circuit board is placed between the internal storage case and the heat-resistant resin case. An electronic component having a heat insulating material interposed therebetween, characterized in that the electronic circuit board is placed in the internal storage case in a direction other than horizontally or vertically, and then filled with resin and fixed. . 6. Used in an environment with severe vibrations, shocks, and temperature changes, an electronic circuit board is housed in an internal housing case, and this is housed in a heat-resistant resin case via a heat insulating material, and the electronic circuit board is housed in a heat-resistant resin case. In an electronic component that is hermetically sealed by venting internal gas through a small-diameter hole, and then pouring an adhesive into the hole and curing it, the airtight sealing hole is counterbore to a specific depth. a counterbore forming means for forming a counterbore, and a gasket which is arranged at the bottom of the counterbore formed by this means, has substantially the same shape as the bottom of the counterbore, and has elasticity, and an adhesive is applied onto the gasket. An electronic component characterized by being poured and hardened. 7. Used in an environment with severe vibrations, shocks, and temperature changes, the electronic circuit board is housed in an internal storage case, this is housed in a heat-resistant resin case, and the electronic circuit board is placed between the internal storage case and the heat-resistant resin case. 1. An electronic component having a heat insulating material interposed therebetween, characterized in that a flange is formed around the internal storage case.