JP2000138304A - Resin-sealed structure and stress relaxing method of resin-sealed product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detach mounting screws for fixing a substrate on a case to bring the substrate from the state of a thermal stress to a free state or to lessen the injection amount of a resin to take measures for reducing the thermally expanded amount of the resin or the like, to suppress the amount of the thermal strain of the resin to the substrate in severe environment, to prevent the generation of nonconforming state such as breakage of the substrate and also to use an urethane material to the material for the resin to reduce the cost of a resin-sealed product in the stress relaxation method of the resin-sealed product. SOLUTION: This stress relaxing method is a method, wherein a substrate 2 is temporarily mounted to a case 1 via sponges 9 for stress absorption at least two places at the four corners of the substrate 2 by jigs 50, and thereafter a resin 7 is injected into the cavity part between the case 1 and the substrate 2. Then, the jigs 50 are detached from the two places to demount the temporary mounting, the resin 7 is re-injected in the cavity part between the substrate 2 and an aperture surface formed in the case 1, and is formed into a solid matter and to the thermal expansion of the resin 7 and the like, strain is not given to the substrate 2 and the motion of the substrate is brought into a free state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-sealed product in which a board on which electronic components are mounted is housed in a case and sealed with a resin. The present invention relates to a resin sealing structure and a stress relaxation method for reducing the amount of distortion and reducing thermal stress.

[0002]

2. Description of the Related Art FIG. 6 is a structural view of a conventional resin-sealed product. FIG. 6 (a) is a structural development view, and FIG. 6 (b) is a structural sectional view after resin sealing. 7A and 7B are views showing a state of occurrence of thermal stress in a conventional resin-encapsulated product, in which FIG. 7A is a perspective view showing a distortion state of a substrate due to thermal expansion, and FIG. 7B is a sectional view showing a distortion state of the substrate due to thermal expansion.

As shown in FIG. 6, a resin-encapsulated product has a board 2 on which electronic components are mounted in a box-shaped case 1 having an open surface, and mounting screws 3 at two diagonal positions in four corners.
After being tightened and housed at a and 3b, the resin 7 is injected and filled through the resin injection nozzle 15 and solidified. In addition, since the resin 7 thermally expands or contracts in a severe thermal environment in the resin-sealed product, the mounting screw 3
Pressure is applied to the substrate 2 fixed at a and 3b, and distortion may occur to cause a problem such as breakage. For this reason, measures such as using a high-priced material such as a silicone material having a wide temperature range of the elastic modulus displacement point as a material of the resin 7 are taken.

The case 1 has a box shape with an open surface, and mounting bosses 1 for mounting and fixing the case 1 to a housing body (not shown) are provided at four corners of the outer peripheral edge of the opening surface.
a and mounting screw holes 1b. In this case 1, a mounting boss 1c for storing the substrate 2 and a mounting screw hole 1d are formed at two diagonal corners in the center of the internal cavity. The case 1 has a notch 1f for fitting the connector 5 mounted on the substrate 2 when the substrate 2 is stored, and a groove 1e for fitting the partition plate 6 therein. After the substrate is stored in the case 1, a resin 7 is injected and filled.

[0005] The board 2 has electronic components mounted thereon. The board 2 is provided at two diagonal lines at the center of the inner cavity of the case 1.
The mounting holes 2a and 2b for mounting and fixing are mounted and fixed with only two mounting screws 3a and 3b, and the mounting density of electronic components on the substrate is improved. The board 2 is housed in the case 1 with the connector 5 attached and fixed by the pins 5a, and then filled with the resin 7.

Further, since the substrate 2 is distorted due to thermal expansion or thermal contraction of the resin 7 due to a severe surrounding thermal environment, four mounting screws are used to suppress the distortion as much as possible. In some cases, the substrate 2 is attached and fixed, but the mounting density of electronic components on the substrate 2 is limited.

The mounting screws 3a and 3b connect the substrate 2 to the case 1
For fixing to the center of the internal cavity of the case 1
Used for earth grounding.

A large-sized electronic component 4 such as an SMD is mounted on a substrate 2 by an IC.
Although it is mounted together with small electronic components such as the above, it is easily affected by distortion to the substrate and the like, and the body and terminals of the large electronic component 4 are easily stressed.

The connector 5 is attached and fixed to the substrate 2 by pins 5a, is integrated, and is used for connection with the outside.

The partition plate 6 is made of a rubber-based material and has convex ribs 6a formed at both ends and a cut-out cut-out hole 6b formed at the lower surface, respectively. After the substrate 2 is stored in the case 1, The partition plate 6 is fitted into the groove 1 e of the case 1, and the connector 5 is pressed by the inner peripheral edge of the notch 6 b to fix the gap between the case 1 and the connector 5. The resin 7 is used to prevent the resin 7 from flowing out of the case 1 when the resin 7 is injected.

The resin 7 protects the substrate 2 by housing the substrate 2 in the center of the internal cavity of the case 1 and then injecting and filling the resin 7 and is used for a resin-sealed product. In addition, since the resin 7 greatly affects the amount of strain applied to the substrate 2 due to thermal expansion or thermal contraction under a severe surrounding thermal environment,
As the material of the resin 7, a high-priced material such as a silicone material having a wide temperature range of an elastic modulus displacement point is used, or a material obtained by impregnating a urethane material with the silicone material using a vacuum casting facility is used. Is done.

The resin injection nozzle 15 is formed by a cylindrical pipe and is a jig for injecting the resin 7 into the case 1 in which the substrate 2 is stored.

The procedure for assembling the resin-sealed product will be described. First, the connector 5 is mounted and fixed to the board 2 with the pins 5a, and after mounting the electronic components, the board 2 is mounted and fixed to the center of the inner cavity of the case 1 with two mounting screws 3a and 3b. The plate 6 is inserted into the notch hole 1 of the case 1.
The connector 5 is fitted into the connector f so as to be pressed. Next, as shown in FIGS. 6A and 6B, the resin 7 is injected by the resin injection nozzle 15. In this injection, 1 g of the inner bottom surface of case 1
A resin 7 is injected and filled into a lower cavity portion 100 between the substrate 1 and the substrate 2 through a gap or the like between the case 1 and the substrate 2. Then, an upper cavity portion 101 between the substrate 2 and the opening surface of the case 1 has an opening surface portion. Is filled with the resin 7 while leaving a certain gap.

The resin-encapsulated product assembled according to the above-described procedure may cause the substrate 2 to be distorted due to the thermal expansion or thermal shrinkage of the resin 7 in a severe surrounding thermal environment, thereby causing problems such as breakage. Was. In the case of a high temperature environment, FIG.
As shown in (b), the resin 7 thermally expands and the substrate 2
Is pushed up in the direction of the opening surface of the case 1. At this time, the substrate 2 is attached to the case 1 with the mounting screws 3a, 3a.
The substrate 2 is pushed up with the position fixed at b as a base point, and the diagonal ends of the substrate 2 are distorted by the amounts of distortion 20 and 21, respectively.

[0015]

As described above, in the conventional resin-encapsulated product, the substrate 2 is fixed to the case 1 at two diagonal positions of the four corners of the substrate 2 with the mounting screws 3a and 3b. After being stored, the resin 7 is injected and filled and solidified. However, this resin-encapsulated product undergoes thermal expansion or contraction of the resin 7 against a severe surrounding thermal environment, so that distortion occurs in the substrate 2. There was a problem that a defect such as breakage occurred. Further, as the material of the resin 7, it was necessary to use a high-priced material such as a silicone material having a wide temperature range of the elastic modulus displacement point.

An object of the present invention is to suppress the amount of thermal strain on a substrate due to thermal expansion or contraction of a resin under a severe surrounding thermal environment, to prevent problems such as breakage, and to use a high cost resin material. An object of the present invention is to reduce the cost by using a urethane-based material without using a silicone material.

[0017]

In order to achieve the above object, according to the present invention, a substrate on which an electronic component is mounted is placed on a pedestal provided inside a case having an open surface and sealed with a resin. In the resin sealing structure, the substrate is provided on the pedestal portion so as to be movable in response to thermal expansion and thermal contraction of the resin, and the resin is sealed. It is.

Further, a gap or an elastic member is interposed between the substrate and the pedestal portion in advance.

Further, a terminal is provided on the substrate, a flexible lead wire is connected to the terminal, and the terminal is drawn out to an opening surface of the case and conductively connected to a metal case.

A plurality of pedestals are provided corresponding to at least each corner of the substrate, and one corner of the substrate is directly fixed to one of the plurality of pedestals, and The other corner is characterized in that a gap or an elastic member is previously interposed between the other pedestals of the plurality of pedestals.

Further, one corner of the substrate is screwed to the one pedestal with a screw to electrically connect the substrate to a metal case, and another corner of the substrate is connected to the other pedestal. On the other hand, the screw is loosened and the gap or the elastic member is interposed.

Further, in a resin-sealed structure in which a substrate on which electronic components are mounted is placed inside a case having an open surface and sealed with a resin, the bottom surface of the case is positioned on the bottom surface side of the substrate. It is dented and deformed to the inside of the case according to the shape of the mounted electronic component, and the resin is sealed with the bottom surface of the deformed case and the substrate and the electronic component kept at a predetermined distance. It is characterized by being stopped.

Further, in a resin-sealed structure in which a substrate on which an electronic component is mounted is placed inside a case having an open surface and is sealed with a resin, the electronic component mounted on the substrate is provided on the substrate. The electronic component is fixed by applying an adhesive to a surface to be mounted, and the rigidity of the substrate is increased.

A board on which electronic components are mounted is mounted on a plurality of pedestals provided inside a case having an open surface, and is provided with a plurality of pedestals corresponding to respective corners of the board, and sealed with a resin. In the method for relieving stress of a resin-encapsulated product, after temporarily mounting each corner of the substrate to each of the pedestals with a screw via a gap or an elastic member, the resin is placed between the bottom surface of the case and the substrate. After the primary injection into the hollow portion, and then removing the screw, the resin is secondary injected into the hollow portion between the substrate and the opening surface of the case.

A board on which electronic components are mounted is mounted on a plurality of pedestals provided inside a case having an open surface, and is provided with a plurality of pedestals corresponding to respective corners of the board, and sealed with a resin. In the method for relaxing stress of a resin-encapsulated product, one corner of the substrate is fixed to the one pedestal portion by tightening a screw, and the other corner of the substrate is spaced from the other pedestal portion by a gap. Alternatively, after mounting with the screws loosened via an elastic member, the resin is injected into a cavity between the inner bottom surface of the case and the substrate and a cavity between the substrate and the opening of the case. It is assumed that.

Further, the resin is made of a urethane-based material.

[0027]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a view showing a stress relaxation structure of a resin-encapsulated product according to a first embodiment of the present invention, wherein FIG.
2 shows a cross-sectional view of the structure after resin sealing, and FIG.
FIG. 4 is a diagram illustrating a stress relaxation state with respect to thermal stress of a resin-encapsulated product according to an embodiment, wherein FIG.
FIG. 3B is a diagram showing a stress relaxation state of a resin-sealed product according to a second embodiment of the present invention, and FIG. 3A is a perspective view of a stress relaxation state of a substrate against a thermal expansion. FIG. 4B is a sectional view showing a stress relaxation state with respect to thermal expansion, FIG. 4 is a sectional view showing a stress relaxation structure of a resin-sealed product showing a third embodiment, and FIG. 5 is a resin sealing showing a fourth embodiment. FIG. 3A is a perspective view of a stress relief structure of a substrate for a stationary product, and FIG.
(B) shows a sectional view after resin sealing.

The same components in the first to fourth embodiments are described in the first embodiment, and the description is omitted in the other embodiments.

The method of relaxing the stress of the resin-sealed product of the first embodiment will be described with reference to FIG. As shown in FIG. 1, this resin-sealed product is a box-shaped case 1 having an open surface.
The substrate 2 on which electronic components are mounted is provided with jigs (screw) 50 at least two diagonally opposite four corners of the substrate 2 inside the case 1 via a sponge 9 for absorbing heat shrinkage stress.
After the temporary assembly is mounted, the resin 7 is injected and filled into the lower cavity portion 100 between the inner bottom surface 1g of the case 1 and the substrate 2, and then the jig 50 (screw) is removed to release the temporary assembly. Then, the resin 7 is injected again into the upper cavity portion 101 between the substrate 2 and the opening surface of the case 1 so as to have a slight gap on the opening surface side, and the resin 7 is thermally expanded or contracted. On the other hand, a stress relaxation method in which the movement of the substrate is set to a free state so as to suppress the distortion to the substrate 2 is used. The substrate 2 is provided with an earth terminal 12. A flexible lead wire 8 is connected to the earth terminal 12, and after the lead wire 8 is drawn out to the opening surface of the case 1, the resin 7 Is injected. The lead wire 8 is conductively connected to a mounting boss 1 a provided on the metal case 1 after the resin 7 is injected, and is grounded to the case 1. The cost of the resin 7 is reduced by using a urethane-based material without using an expensive silicone material.

The metal case 1 has a box shape with an open surface, and mounting bosses 1a for mounting and fixing the case 1 to a housing body (not shown) are provided at four corners of the outer peripheral edge of the opening surface. , And a mounting screw hole 1b are formed.
In this case 1, a mounting boss 1c, which is a pedestal portion for temporarily mounting the substrate 2 in the central portion of the internal cavity, and a temporary assembling screw hole 1d are formed at two diagonal corners.
When the substrate 2 is housed in the case 1, a notch 1 for fitting a connector 5 mounted on the substrate 2 is provided.
f, and a groove 1e into which the upper partition plate 6 and the lower partition plate 10 are fitted. After the substrate 2 is stored in the case 1, a resin 7 is injected and filled.

Electronic components are mounted on the substrate 2, and the substrate 2 is provided at two diagonal lines at the center of the inner cavity of the case 1.
Mounting holes 2a and 2b for temporarily assembling are temporarily provided, and are temporarily assembled with two temporary assembling jigs (screw) 50.
After the resin 7 is injected into the lower cavity 100, the jig 50 is removed, and then the resin 7 is injected into the upper cavity 101. An earth terminal 12 is provided on the substrate 2 and is conductively connected to the lead wire 8.

A temporary assembling jig (screw) 50 is used for temporarily assembling the substrate 2 at the center of the inner cavity of the case 1.
The resin 7 is removed after being injected into the lower cavity portion 100.

A large electronic component 4 such as an SMD is mounted on the substrate 2 by an IC.
And so on.

The connector 5 is fixed to the board 2 by pins 5a, is integrated with the board 2, and is used for connection to the outside.

The upper partition plate 6 is made of a rubber-based material and has ribs 6a of convex shape formed at both ends and a cut-out notch 6b formed at the lower surface. After the substrate 2 is stored in the case 1, The upper partition plate 6 is fitted into the groove 1 e of the case 1, and the connector 5 is fitted with the fitted notch hole 6.
b, and is fixed so as to fill the gap between the case 1 and the connector 5 by pressing the inner peripheral edge of the case b. The upper partition plate 6 is used to prevent the resin 7 from flowing out of the case 1 when the resin 7 is injected, and to compress when the resin 7 thermally expands and the connector 5 rises. It is configured to be.

The resin 7 protects the substrate 2 by injecting and filling after the substrate 2 is housed in the center of the internal cavity of the case 1 and is used for a resin-sealed product. In addition, since this resin-encapsulated product employs a method of relieving thermal stress in a severe surrounding thermal environment, the resin 7 is made of a low-cost material without using an expensive silicone material or the like. Urethane materials are used.

The ground lead 8 is connected to a ground terminal 12 provided on the substrate 2 and extends to the opening surface of the case 1. When the case 1 is mounted on a housing body (not shown), the ground lead 8 is tightened by a mounting screw to a mounting boss 1a of the case 1 and is connected to ground.

The ground lead 8 may be connected to the ground terminal 12 by soldering instead of the screw.

The heat-shrinkage stress-absorbing sponge 9 is formed in a donut shape from a rubber-based material. The sponge 9 is mounted under the mounting holes 2a and 2b of the substrate 2 in which the substrate 2 is temporarily assembled and stored in the case 1. The resin 7 is compressed when thermally contracted, and is used to reduce stress on the substrate 2 and reduce the amount of distortion. The thickness of the heat shrinkage stress absorbing sponge 9 corresponds to a gap between the substrate 1 and the mounting boss 1c of the case 1, and the thickness is based on a temperature change, a resin thickness, and an expansion coefficient. It is determined by the amount of movement when the resin shrinks.

The lower partition plate 10 is made of a rubber material, and is formed with a convex rib 10a on the bottom surface and both ends and a cutout hole 10b on the upper surface. When the board 2 is accommodated in the case 1, the connector 5 is fitted into the notch hole 10 b of the lower partition plate 10 and abuts thereon, so that the gap between the case 1 and the connector 5 is filled. To be fixed. The lower partition plate 10 is used to prevent the resin 7 from flowing out of the case 1 when the resin 7 is injected, and compresses when the connector 5 is lowered when the resin 7 is thermally contracted. It is configured as follows. This is used to alleviate the stress on the substrate 2 integrally connected to the connector 5 and reduce the amount of distortion. That is, the movement of the connector 5 can be followed by elastically sandwiching the connector 5 between the upper and lower partition plates 6 and 7 which are elastic members. Alternatively, the upper and lower partition plates 6 and 7 may be used as fixed members, and the lead member connecting the connector 5 and the substrate 2 may be made of a flexible material.

The ground terminal 12 is connected to the ground land provided on the substrate 2 by soldering.
Is used for ground connection to the metal case 1 via the.

The resin injection nozzle 15 is formed by a cylindrical pipe, and is a jig for injecting the resin 7 into the case 1 in which the substrate 2 is stored.

The procedure for assembling the resin-sealed product will be described. First, the connector 5 is attached and fixed to the board 2 with the pin 5a, and the electronic component and the ground lead 8 are connected and mounted. Then, the board 2 is connected to the board 2 at the center of the inner cavity of the case 1. The connector 5 is fitted so as to be in contact with the lower partition plate 10, and is temporarily assembled with at least two jigs 50 via the sponge 9 for absorbing heat shrinkage stress. Then, the grounding lead 8 is connected to the case 1
After that, the partition plate 6 is fitted into the notch 1 f of the case 1 and is brought into contact with the connector 5. Next, as shown in FIGS. 1A and 1B, the resin injection nozzle 1
In step 5, the resin 7 is primarily injected. In the primary injection of the resin 7, first, the resin 7 is injected and filled into a lower cavity portion 100 between the inner bottom surface 1 g of the case 1 and the substrate 2 through a gap or the like between the case 1 and the substrate 2. After the jig 50 is removed, the resin 7 is placed in the upper cavity portion 101 between the substrate 2 and the opening surface of the case 1 while leaving a certain gap in the opening surface portion.
Next, filling is performed. In the temporary assembly using the jig 50, the sponge 9 for absorbing heat shrinkage stress is lightly tightened in the original uncompressed state.

The resin-encapsulated product assembled in the above procedure absorbs and relaxes the strain on the substrate 2 in the severe surrounding thermal environment, thereby preventing the occurrence of problems such as damage to the substrate 2. .
In a high temperature environment, as shown in FIG. 2A, the resin 7 thermally expands, and the substrate 2 is pushed up in the direction of the opening surface of the case 1. At this time, the substrate 2 is the case 1
The substrate 2 is moved up from the mounting boss 1c provided at the position to the position of the gap 32, and the substrate 2 is entirely pushed up by the gap 32 from which the gap 30 at the time of assembly is subtracted, and the distortion of the substrate 2 is absorbed. Will be. At this time, the upper partition plate 6 in contact with the connector 5 is compressed, and the connector 5 is pushed up integrally with the substrate 2. At this time,
The lower partition plate 10 extends upward by its elastic force. Next, in a low-temperature environment, as shown in FIG. 2B, the resin 7 thermally contracts, and the substrate 2 contracts in the direction of the inner bottom surface 1g of the case 1. At this time, the distortion of the substrate 2 is absorbed by the heat shrinkage stress absorbing sponge 9 mounted between the substrate 2 and the mounting boss 1c provided on the case 1, and the substrate 2 and the mounting boss 1c Is lowered to a position where a gap 34 is formed. At this time, connector 5
The lower partition plate 10 in contact with the connector 5 is compressed and lowered integrally with the substrate 2. At this time, the upper partition plate 6 extends downward by its elastic force.

Next, a method of relieving the stress of the resin-sealed product of the second embodiment will be described with reference to FIG. In this resin-sealed product, as shown in FIG. 3, the substrate 2 is tightened at one of four corners inside the case 1 with metal mounting screws 3a (or 3b) or the like while also serving as a housing ground. In other places, a heat-shrinkage stress absorbing sponge 9 is fitted between the substrate 2 and the case 1 in other places, and mounting screws 3b are attached.
(Or screws 3a) are loosened and the substrate 2 is tightened and mounted in a floating state. After that, the resin 7 is attached to the inner bottom surface 1g of the case 1 and the lower cavity portion 100 between the substrate 2 and the substrate 2, and Upper cavity portion 10 with opening surface of case 1
1 is injected and solidified so as to have a slight gap on the opening side. Accordingly, when the resin 7 thermally expands or contracts, the resin-encapsulated product has the other three parts except for one of the four corners of the substrate 2 which is directly tightened with the mounting screws 3a (or 3b). A stress relaxation method is used in which the movement of the substrate 2 at various places is made free. The cost of the resin 7 is reduced by using a urethane-based material without using an expensive silicone material. still,
In this example, the substrate 2 is normally slightly bent, but the stress in this case can be absorbed by the sponge 9 for absorbing heat shrinkage stress. Further, the connector 5 is also in a slightly inclined state, but this is also an upper and lower partition plate 6,1 which is also an elastic member.
A value of 0 can absorb the stress.

Case 1 is the same as in the first embodiment, and a description thereof will be omitted.

The electronic component is mounted on the substrate 2, and the substrate 2 is disposed at two diagonal lines at the center of the inner cavity of the case 1.
Mounting holes 2a and 2b for mounting
One of the mounting screws 3a, 3b is fastened and fixed also as a housing ground, and the other is loosened via the heat-shrinkage stress absorbing sponge 9 to loosen the board 2 and tighten the board. Fixed. Next, the resin 7 is injected and filled into the lower cavity portion 100 and the upper cavity portion 101.

The mounting screws 3a and 3b connect the substrate 2 to the case 1
And a metal mounting screw 3a for directly tightening the substrate 2 to the case 1 directly and also as a ground (in this case, a ground terminal provided on the substrate 2). The conductive connection between the ground terminal and the case 1 is made by the contact of the screw head of the mounting screw 3a), and the mounting screw 3b fits the sponge 9 for absorbing heat shrinkage stress between the substrate 2 and the case 1. Then, the substrate 2 is loosened so as to float and fixed by fastening (therefore, the temporary assembling jig 50 is not used in this example).

Large electronic component 4 such as SMD and connector 5
The upper partition plate 6, the lower upper partition plate 10, and the resin injection nozzle 15 are the same as in the first embodiment as in the case 1, and the description thereof is omitted.

The resin 7 protects the substrate 2 by housing the substrate 2 in the center of the inner cavity of the case 1 and then injecting and filling the resin 7, and is used for a resin-sealed product. In addition, since this resin-encapsulated product employs a method of relieving thermal stress in a severe surrounding thermal environment, the resin 7 is made of a low-cost material without using an expensive silicone material or the like. Urethane materials are used.

In the second embodiment, the grounding lead wire 8 described in the first embodiment is electrically connected by fastening the substrate 2 to the case 1 with a single metal mounting screw 3a also serving as the ground. Not used.

The heat-shrinkage stress-absorbing sponge 9 is formed of a rubber-based material into a donut shape, and is attached to a lower portion of the mounting hole 2a or 2b of the substrate 2 where the substrate 2 is floated. It is used to reduce the stress on the substrate 2 and reduce the amount of strain by being compressed when thermally contracted.

The procedure for assembling the resin-sealed product will be described. First, the connector 5 is attached and fixed to the board 2 with pins 5a, and electronic components are mounted to integrate the board 2 and the connector 5 together. Then, after the lower partition plate 10 is fitted into the lower part of the groove 1 e of the case 1, the substrate 2 is fitted into the central portion of the internal cavity of the case 1 so that the connector 5 comes into contact with the lower partition plate 10, One place is directly fastened to the mounting boss 1c of the case 1 with a metal mounting screw 3a, which also serves as ground, and the other part is mounted and fixed with a mounting screw 3b via a sponge 9 for absorbing heat shrinkage stress. At the place where the sponge 9 is attached via the heat shrinkage stress absorbing sponge 9, the sponge 9 is not pressed and the substrate 2 is lightly tightened in a floating state. Next, the partition plate 6 is fitted into the notch 1f of the case 1 so that the connector 5 comes into contact with the notch 1f. As shown in FIGS. 1 (a) and 3 (b), the resin 7 is inject. In this injection, first, a resin 7 is injected and filled into a lower cavity portion 100 between the inner bottom surface 1g of the case 1 and the substrate 2 through a gap between the case 1 and the substrate 2, and then the opening of the substrate 2 and the opening of the case 1 The upper cavity portion 101 with the surface is injected and filled with a certain gap left in the opening surface.

The resin-encapsulated product assembled according to the above procedure absorbs and relaxes the strain on the substrate 2 in the severe surrounding thermal environment, thereby preventing the occurrence of problems such as damage to the substrate 2. .
In the case of a high temperature environment, as shown in FIGS. 3A and 3B, the resin 7 thermally expands, and the substrate 2 is pushed up in the direction of the opening surface of the case 1. At this time, the board 2 is fixed with the mounting screw 3b via the heat shrinkage stress absorbing sponge 9 with respect to the mounting boss 1c provided on the case 1 where the mounting screw 3a is tightened with the mounting screw 3a. It is pushed up from the mounting boss 1c provided in the case 1 to the position of the gap 22, and the stress due to the distortion of the substrate 2 is absorbed by half. Also, the distortion 2 in FIG.
Reference numerals 0 and 21 denote the amounts of distortion at positions different from the two corners where the substrate 2 is mounted by the mounting screws 3a and 3b. (Although not shown, a gap is provided between the screw head of the mounting screw 3b and the board 2 for the purpose of pushing up the board 2). Next, in a low temperature environment, the resin 7 thermally contracts, and the substrate 2 contracts in the direction of the inner bottom surface 1g of the case 1. At this time, the heat-shrinkage stress absorbing sponge 9 mounted between the substrate 2 and the mounting boss 1c provided on the case 1 is compressed except for the place where the substrate 2 is tightened by the mounting screw 3a. The stress due to is reduced by half. At this time, the connector 5 is
The lower partition plate 10 in contact with the substrate 2 is compressed and lowered integrally with the substrate 2. As described above, in the present embodiment, the lengths of the distortion amounts 20 and 21 can be reduced as compared with the related art.

In the first and second embodiments described above, the sponge 9 for absorbing heat shrinkage stress is used, but the sponge 9 for absorbing heat shrinkage stress is not interposed.
The resin may be injected with the gap provided. In this case, for example, the board 2 may be floated using the connector 5 and the resin may be injected while being floated by the gap. In the first embodiment and the second embodiment, the screw fastening is limited to two locations on the diagonal line. However, the present invention is not limited to this, and the present invention is applied to a fastener in which three or four locations are screwed. Is also good. Further, when a gap is provided in the second embodiment without using the heat shrinkage stress absorbing sponge 9 in the mounting screw 3b, a slight stress is applied to the substrate 5, but the heat shrinkage stress absorbing sponge 9 is used in the mounting screw 3a side. You may make it absorb stress.

Next, a method of relieving the stress of the resin-sealed product of the third embodiment will be described with reference to FIG. This resin-sealed product is, as shown in FIG.
Is formed such that the gap between the inner bottom surface 1g of the case 1 and the electronic components and the like mounted on the substrate 2 is a small width and evenly spaced when the substrate 2 is mounted. The substrate 2 is placed inside the case 1 and the substrate 2
At least two diagonal lines at the four corners of
a, 3b, the resin 7 is mounted on the lower cavity 100 between the inner bottom surface 1g of the case 1 and the substrate 2.
The amount of resin injected into the substrate 2 is regulated to a small amount having a uniform thickness, and the amount of the resin 7 injected into the upper cavity portion 101 between the substrate 2 and the opening surface of the case 1 is also reduced to the substrate 2. A stress relaxation method in which a small amount of a uniform thickness is provided on the mounted electronic component, the amount of strain on the substrate 2 is suppressed with respect to thermal expansion and thermal contraction of the resin 7, and thermal stress is reduced. Used. The cost of the resin 7 is reduced by using a urethane-based material without using an expensive silicone material.

The case 1 has a box-like shape with an open surface, and the inner bottom surface 1g is formed in an uneven shape so that the gap between the electronic component and the like mounted on the substrate 2 is a small width and is evenly spaced. A mounting boss 1 a for mounting and fixing the case 1 to a housing body (not shown), and a mounting screw hole 1 are provided at four corners of the outer peripheral edge of the opening surface of the case 1.
b is formed. In the case 1, mounting bosses 1c and mounting screw holes 1d for fastening the substrate 2 with mounting screws 3a and 3b are formed at two diagonal corners of the case 1 at the center of the internal cavity. The case 1 has a notch 1f for fitting the connector 5 mounted on the substrate 2 when the substrate 2 is stored, and a groove 1e for fitting the partition plate 6 therein. After the substrate is stored in the case 1, the resin 7
Is injected and filled.

An electronic component is mounted on the substrate 2, and the substrate 2 is mounted on two diagonal lines at the center of the inner cavity of the case 1.
Mounting holes 2a and 2b are provided for mounting the substrate 2. The substrate 2 is fixedly fastened to the case 1 with two mounting screws 3a and 3b, which also serve as a housing ground. Next, the resin 7 is injected and filled.

The mounting screws 3a and 3b connect the substrate 2 to the case 1
The substrate 2 is firmly fastened and fixed directly to the case 1 while also serving as a ground.

Large electronic component 4 such as SMD and connector 5
The partition plate 6, the resin 7, and the resin injection nozzle 15 are the same as those in the first embodiment, and a description thereof will be omitted.

The grounding lead wire 8 and the sponge 9 for absorbing heat shrinkage stress described in the first and second embodiments.
The lower partition plate 10 is not used in the third embodiment.

The procedure for assembling the resin-sealed product will be described. First, the connector 5 is mounted and fixed to the board 2 with the pins 5a, and after mounting the electronic components, the board 2 is mounted on the mounting boss 1c at the center of the inner cavity of the case 1 with at least two mounting screws 3a and 3b. Fixed. Next, the partition plate 6 is fitted into the notch 1 f of the case 1 so as to press the connector 5, and the resin 7 is injected by the resin injection nozzle 15 as shown in FIGS. 1 (a) and 4. In this injection, first, a resin 7 is injected and filled into a lower cavity portion 100 between the inner bottom surface 1g of the case 1 and the substrate 2 through a gap between the case 1 and the substrate 2, and then the opening of the substrate 2 and the opening of the case 1 The substrate 2 in the upper cavity portion 101
Is injected and filled in a small amount with a uniform thickness on the electronic component mounted on the substrate.

The resin-encapsulated product assembled according to the above procedure reduces the amount of the resin 7 injected into the severe surrounding thermal environment to suppress the thermal expansion or thermal contraction of the resin 7, To prevent the occurrence of problems such as damage to the substrate 2.

Next, a method of relieving the stress of the resin-sealed product of the fourth embodiment will be described with reference to FIG. As shown in FIG. 5, this resin-encapsulated product is a product in which the strength of the substrate 2 used in the first embodiment, the second embodiment, and the third embodiment is further enhanced, and is mounted on the substrate 2. SMD, QFP
A large-sized electronic component 4 is coated with an adhesive material 11 on a surface to be mounted on the substrate 2 and is fixed by bonding.
The area equivalent to the area to be bonded increases the rigidity of the substrate 2, and the effect increases as the number of the electronic components 4 bonded increases. In addition, lead soldering connection of the electronic component 4 to the substrate 2 is facilitated. Thereby, besides suppressing the amount of distortion to the substrate 2 due to the thermal expansion and thermal contraction of the resin 7 according to the first embodiment, the second embodiment and the third embodiment, the rigidity of the substrate 2 is further increased. Then, the substrate 2 can be strengthened so as to withstand thermal stress. In this example, the board 2 is fixed to the case 1 by two mounting screws 3a and 3b. However, when there is no restriction on the mounting density of electronic components on the board 2, four boards are mounted. The strength of the substrate 2 may be strengthened by fixing it with screws or the like.

[0066]

As described above, according to the present invention, the amount of thermal strain on the substrate due to the thermal expansion or contraction of the resin in a severe surrounding thermal environment is suppressed, and problems such as breakage are prevented. At the same time, the cost can be reduced by using a urethane-based material without using an expensive silicone material as the resin material.

[Brief description of the drawings]

FIG. 1 is a diagram showing a stress relaxation structure of a resin-sealed product according to a first embodiment of the present invention.

FIG. 2 shows a stress relaxation state diagram of the resin-sealed product according to the first embodiment of the present invention.

FIG. 3 shows a stress relaxation structure diagram of a resin-sealed product according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing a stress relaxation structure of a resin-encapsulated product according to a third embodiment of the present invention.

FIG. 5 is a view showing a stress relaxation structure of a resin-sealed product substrate according to a fourth embodiment of the present invention.

FIG. 6 shows a structural view of a conventional resin-sealed product.

FIG. 7 shows a thermal stress generation state diagram of a conventional resin-encapsulated product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Case 2 ... Board 3a ... Mounting screw 3b ... Mounting screw 4 ... Large electronic component 5 ... Connector 6 ... Upper partition plate 7 ... Resin 8 ... Ground wire 9 ... Sponge for absorbing heat shrinkage stress 10 ... Lower partition plate 11 ... Adhesive 12 ... Ground terminal 15 ... Resin injection nozzle 50 ... Jig for temporary assembly ( screw)

Claims (10)

[Claims] 1. A resin-sealed structure in which a substrate on which electronic components are mounted is mounted on a pedestal portion provided inside a case having an open surface, and is sealed with a resin. A resin sealing structure provided on the pedestal portion so as to be movable in response to thermal expansion and thermal contraction, and wherein the resin is sealed. 2. The resin sealing structure according to claim 1, wherein a gap or an elastic member is interposed between the substrate and the pedestal in advance. 3. The terminal according to claim 1, wherein a terminal is provided on the substrate, a flexible lead wire is connected to the terminal, and the terminal is drawn out to an opening surface of the case and conductively connected to a metal case. Resin sealing structure. 4. A plurality of pedestals are provided corresponding to at least each corner of the substrate, and one corner of the substrate is directly fixed to one of the plurality of pedestals, and The resin sealing structure according to claim 1, wherein a gap or an elastic member is previously interposed between the other corners of the plurality of pedestals at the other corners. 5. One corner of the substrate is screwed to the one pedestal with a screw, the substrate and a metal case are conductively connected, and the other corner of the substrate is connected to the other pedestal. The resin sealing structure according to claim 4, wherein the screw is loosened and the gap or the elastic member is interposed. 6. A resin-sealed structure in which a substrate on which electronic components are mounted is placed inside a case having an open surface, and is sealed with a resin, wherein the bottom surface of the case is located on the bottom surface side of the substrate. It is dented and deformed to the inside of the case according to the shape of the mounted electronic component, and the resin is sealed with the bottom surface of the deformed case and the substrate and the electronic component kept at a predetermined distance. A resin sealing structure characterized by being stopped. 7. A resin-sealed structure in which a substrate on which an electronic component is mounted is placed inside a case having an open surface, and is sealed with a resin. A resin sealing structure wherein an adhesive is applied to a surface to be mounted to fix the electronic component, thereby increasing the rigidity of the substrate. 8. A substrate on which electronic components are mounted is mounted on a plurality of pedestals provided inside a case having an open surface, and is provided at a plurality of pedestals corresponding to respective corners of the substrate, and is sealed with a resin. In the method for relieving stress of a resin-encapsulated product, after temporarily mounting each corner of the substrate to each of the pedestals with a screw through a gap or an elastic member, the resin is placed between the bottom surface of the case and the substrate. A primary injection into a hollow portion of the resin-encapsulated product, then, after removing the screw, a secondary injection of the resin into a hollow portion between the substrate and an opening surface of the case. Stress relaxation method. 9. A board on which electronic components are mounted is mounted on a plurality of pedestals provided inside a case having an open surface and provided at a plurality of pedestals corresponding to respective corners of the board, and sealed with a resin. In the method for relieving stress of a resin-encapsulated product, one corner of the substrate is fixed to the one pedestal portion by screwing, and the other corner of the substrate is spaced from the other pedestal portion by a gap. Alternatively, after mounting with the screws loosened via an elastic member, the resin is injected into a cavity between the inner bottom surface of the case and the substrate and a cavity between the substrate and the opening of the case. Stress relief method for resin-sealed products. 10. The resin sealing structure according to claim 1, wherein the resin is made of a urethane-based material.