JP2012186371A - Method of manufacturing electronic circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing an electronic circuit device by newly finding a sealing method that can be materialized with a small quantity of resin and can cope with circuit boards having various component disposition.SOLUTION: In this method of manufacturing the electronic circuit device, a liquefied resin material 30 is introduced into a casing 11 for housing a circuit board 12 mounted with electronic components 13; the surface of the introduced resin material 30 is covered with a cover member 20 to be pushed-in; and the resin material 30 is cured after partially pushing it up. The cover member 20 formed so as to cover the circuit board 12 mounted with the electronic components 13 has a hole through which the liquefied resin material 30 can pass at a position corresponding to the tallest electronic component 13 mounted to the circuit board 12, and when the surface of the resin material 30 is pushed-in by the cover member 20, the liquefied resin material 30 seals the electronic components 13 and the surplus resin material 30 flows out from the hole.

Description

  The present invention relates to a method for manufacturing an electronic circuit device. More specifically, the present invention relates to a method for manufacturing an electronic circuit device in which a circuit board on which an electronic component is mounted together with a resin filled for sealing is housed in a housing.

  In an electronic circuit device, in order to improve reliability such as dust proof, moisture proof, and insulation, circuit boards are often sealed using various resins. The resin material for that purpose is high in cost and can be an obstacle to weight reduction. Therefore, it is desired to reduce the amount of resin material used as much as possible.

  As resin sealing in an electronic circuit device, generally, a method of incorporating a circuit board into a casing having a flat bottom surface and pouring the resin there is performed. However, in this method, when there is a variation in the height of electronic components to be mounted, it is necessary to fill the resin until the tallest component is covered. The resin will be introduced.

  There is a method in which electronic components are mounted on both the front and back sides of a circuit board, and a tall electronic component is mounted below the circuit board. FIG. 3 is a schematic cross-sectional view of an example of an electronic circuit device according to a conventional method. In this method, the housing 11 is processed in advance into a predetermined shape so as to match the uneven shape of the electronic component 13 mounted on the lower side of the circuit board 12. By doing so, the tall electronic component 13 mounted on the lower side is surrounded by the casing 11, so that the electronic component 13 mounted on the lower side of the circuit board 12 is sealed. The amount of the resin material 30 can be relatively reduced. Since the short electronic component 13 is mounted on the upper side of the circuit board 12, the amount of the resin material 30 required can be reduced as a whole.

According to Patent Document 1, it is disclosed that a main body portion of an electronic component mounted on a circuit board is exposed and only a conductive portion is resin-sealed.
According to Patent Document 2, by providing an intrusion prevention means that is in close contact with a creeping portion on the back surface side of the circuit board along the inner peripheral surface of the bottom surface portion of the housing, sealing is provided inside the intrusion prevention means. It is disclosed that the amount of resin is reduced without using a resin for the purpose.
According to Patent Document 3, it is disclosed that a partition wall that partitions a resin-filled region and a non-filled region is provided in a housing, and the amount of resin is reduced by limiting the region filled with resin.
According to Patent Document 4, it is disclosed that the amount of resin is reduced by partitioning into a region where resin molding is performed and a region where resin molding is not performed by a cover having a through hole in the housing.
According to Patent Document 5, resin sealing portions are provided on both surfaces of a circuit board on which electronic components are mounted, and a plurality of openings are provided in the resin sealing portion on the lower surface side of the circuit board, thereby ensuring reliability and heat dissipation. It is disclosed to improve performance.

JP 2005-86116 A JP 2005-101291 A JP 2005-142213 A JP 2008-277591 A JP 2010-86952 A

  As shown in FIG. 3 referred to above, according to the method of mounting the tall electronic component 13 on the lower side of the circuit board 12, the housing 11 must be processed into a complicated shape. For this reason, design changes are often required for existing electronic circuit devices, which tends to increase costs. In addition, there is a concern that the resin material 30 cannot be completely filled into the inside of the housing 11 having a complicated shape and an air pocket is generated. In order to prevent such air accumulation, the filling speed of the resin material 30 can be slowed, the filling process can be divided into several times, or the resin can be filled while defoaming in a vacuum environment. However, all of them have the disadvantages that the manufacturing method becomes complicated, the number of processes increases, the introduction of special equipment is required, and there are restrictions on the parts to be used such that parts that cannot be vacuumed cannot be used.

  For example, when the resin material is filled up to a certain height and a part of a tall part is exposed as in the technique of Patent Document 1, an interface between the part and the resin occurs, and peeling or the like occurs at the interface. It is likely to occur, and there is a concern about deterioration of moisture resistance reliability. Furthermore, for example, the present inventors have studied a method of dividing the filling operation by providing a partial enclosure or the like, but the working efficiency is deteriorated. In addition, as a result of a separate filling operation, a resin interface is generated due to a difference in the filling process, and peeling or the like is likely to occur, and there is a concern about deterioration of moisture resistance reliability.

  The present invention has found a sealing method that can be applied to circuit boards of various arrangements without complicating the shape of the housing and can be realized with a small amount of resin, and a method for manufacturing an electronic circuit device. The issue is to provide. Furthermore, another object of the present invention is to provide an electronic circuit device sealed with a small amount of resin and a member suitable for the above manufacturing method.

As a result of intensive studies by the inventors, the present invention as described below has been completed.
[1] A liquefied resin material is introduced into a housing that houses a circuit board on which electronic components are mounted, and the surface of the introduced resin material is covered with a cover member and pushed in, and the resin material is partially raised, and then the resin An electronic circuit device manufacturing method for curing a material. The cover member is formed so as to cover the circuit board on which the electronic component is mounted. A hole corresponding to the tallest electronic component mounted on the circuit board has a hole through which the liquefied resin material can pass. The resin material liquefied by pushing the surface of the resin material with the cover member can seal the electronic component. It is comprised so that the excess resin material can flow out from the said hole. This is a manufacturing method using such a cover member.
[2] The manufacturing method according to [1], wherein the height of the tallest electronic component is lower than the height of the wall portion of the housing.
[3] The method according to [1] or [2], wherein the cover member is removed after the resin material is cured.
[4] The manufacturing method according to any one of [1] to [3], wherein the cover member has ribs arranged in a lattice shape.
[5] An electronic circuit device of the present invention includes a circuit board on which a plurality of electronic components having different heights are mounted, and a sealing member made of a resin material that covers the electronic components. In this electronic circuit device, the standard height of the sealing member from the circuit board is lower than the tallest electronic part mounted on the circuit board, and a plurality of electronic parts that can be regarded as having almost the same height. Covers the height of the top of the. The sealing member extends so as to cover the periphery of the electronic component protruding from the standard height and the top end portion.
[6] The present invention also provides a cover member used when covering a circuit board on which electronic components are mounted. The cover member has a flat portion and a protruding portion protruding in a cylindrical shape from the flat portion. In this cover member, a flat portion that covers the height of the top end of each of the plurality of electronic components that can be regarded as having substantially the same height is installed in parallel to the circuit board. At this time, the projecting portion can cover the periphery of a tall electronic component mounted on the circuit board.

  According to the present invention, in regions where electronic components are not mounted and regions where electronic components with a short height are mounted, the resin material is pushed into a position close to the circuit board to be cured, so that tall electronic components coexist. However, use of a useless resin material can be suppressed. By suppressing the resin material, cost reduction and weight reduction are achieved. Since the resin material liquefied by the cover member is pushed in, the shape of the cured resin material basically depends on the shape of the cover member, and the cured resin material can be easily molded into a desired shape.

According to the preferred embodiment of the present invention, the height of the wall portion of the housing is configured to be higher than the height of the tallest component, and when the cover member pushes in the liquid surface (surface) of the resin material, It is possible to prevent the resin material from flowing out to the outside undesirably.
According to another preferred embodiment of the present invention, the cover member is provided with ribs, and the strength of the cover member is improved.

It is sectional drawing which represents the manufacturing method of this invention typically. It is the top view and side surface perspective view in 1 process of the manufacturing method of this invention. It is a schematic cross section of an example of an electronic circuit device according to a conventional method.

  In the present invention, a cover member having a predetermined shape is used when a circuit board on which electronic components are mounted is sealed with resin. FIG. 1 is a cross-sectional view schematically showing the production method of the present invention. FIG. 1B is a schematic cross-sectional view showing the housing 11, the circuit board 12 accommodated in the housing 11, and the electronic component 13 mounted on the circuit board 12.

  The circuit board 12 used in the present invention and the electronic component 13 mounted thereon are not particularly limited. The circuit board 12 is generally a plate-like insulator, and desired wiring is formed of a conductive material on the surface and / or inside thereof. The electronic component 13 is mounted on the circuit board 12 so as to constitute a predetermined circuit structure. The electronic component 13 has various heights according to its type, and the cross section of the circuit board 12 and the electronic component 13 mounted thereon has a predetermined uneven shape. In the present invention, the “back height” of the electronic component 13 means the height of the circuit board 12 from the board surface on which the electronic component is mounted. The arrangement of the electronic components 13 is not limited to the illustrated mode.

  In the conventional method, when all the tall electronic components 13 are sealed with resin, not only the tall electronic components 13 but also the regions where the short electronic components 13 and the electronic components 13 do not exist. An amount (thickness) of resin material sufficient to cover the high electronic component 13 had to be filled, which was a factor in increasing costs and weight.

  According to the present invention, the circuit board 12 is accommodated in the housing 11. The shape and material of the housing 11 are not particularly limited as long as the periphery of the circuit board 12 and the electronic component 13 can be filled with resin by fastening the liquefied resin material. For example, the housing 11 has a rectangular parallelepiped shape in which only the upper part is open, and is made of a material that does not cause a chemical reaction with the resin material.

  In the present invention, the height of the tallest electronic component 13 is preferably lower than the height of the wall portion of the housing 11. Thereby, when pushing in the liquid level (surface) of a resin material with the cover member mentioned later, it can prevent that the resin material flows out to the exterior of the housing | casing 11 undesirably. That is, according to the present invention, even when a large amount of resin material is filled to generate an excess resin material, the excess resin material overflows from the hole of the cover member, so that the amount of resin can be managed. Further, according to the present invention, since the resin material is cured while being covered with the cover member, dirt or the like hardly adheres to the resin surface during the curing, and the surface of the cured resin material is clean.

  Preferably, a concave portion or a convex portion is appropriately formed in the housing 11, whereby the positioning of a cover member described later can be facilitated, or the cover member can be stably pressed down.

  According to the present invention, the liquefied resin material is introduced in a state where the circuit board 12 on which the electronic component 13 is mounted is housed in the housing 11 as shown in FIG. FIG. 1C is a cross-sectional view schematically showing a process of introducing the liquefied resin material into the housing. A resin material 30 is introduced into the housing 11 from the resin filling nozzle 31 and filled around the circuit board 12 and the electronic component 13. However, according to the present invention, it is not necessary to introduce an amount of the resin material 30 that reaches the highest part of the tallest electronic component 13, and it is sufficient to introduce a smaller amount of the resin material 30.

  In the present invention, the material of the resin material 30 is not particularly limited, and a resin material that can be cured by heat, light, moisture, or the like can be appropriately used. The fact that the resin material 30 is liquefied means that the resin material 30 has sufficient fluidity to go around the circuit board 12 when the resin material 30 is introduced into the housing 11 from the resin filling nozzle 31. The viscosity, elasticity, etc. are not particularly limited. Either a resin material used with a solvent or a solvent-free resin material can be used in the present invention.

  According to the present invention, after introducing the resin material 30, the surface of the introduced resin material 30 is covered with the cover member 20, and the resin material 30 is cured after being pushed to a predetermined depth. FIG. 1A is a schematic cross-sectional view of a cover member, and FIGS. 1D and 1E are cross-sectional views schematically illustrating a step of curing the resin material after covering the resin material with the cover member and pushing it in. FIG. A downward arrow in the drawing represents pushing the cover member 20 in this direction. At this time, in a region where the electronic component 13 is not mounted or a region where the short electronic component 13 is mounted, the resin material 30 is pushed out from the region by pushing the cover member 20 to a predetermined depth. Therefore, the amount of the resin material 30 used can be reduced.

  Specifically, the cover member 20 is designed so as to match the arrangement of the electronic components 13 in the electronic circuit device to be manufactured. More specifically, a portion of the cover member 20 that covers a region where the electronic component 13 does not exist or a region where a plurality of short electronic components 13 are mounted is flat and protrudes deeply downward. Conversely, the portion covering the region where the tall electronic component 13 is mounted is the upper half of the tall electronic component 13 when the flat portion of the cover member 20 covering the short electronic component 13 portion is taken as a reference. It is formed to project like a cylinder covering the periphery of the part. That is, the cover member 20 having a shape that follows the mounting state of the electronic component 13 on the circuit board 12 is configured. In other words, it is preferable that the cover member 20 has a concavo-convex shape in which the concavo-convex shape of the circuit board 12 and the electronic component 13 mounted thereon is reversed. That is, since the plurality of short electronic components 13 that are present have different heights, they have an uneven shape in which a flat portion corresponding to the height of the electronic components 13 is provided. The uneven shape of the flat end portion is formed by connecting flat portions having slightly different heights so as to cover the height of the top end of a plurality of short electronic components 13 that can be regarded as having substantially the same height. Yes. In consideration of this, when designing an electronic circuit device, the uneven shape due to the arrangement of the electronic components 13 is determined. Therefore, the cover member 20 that easily conforms to the electronic circuit device can be obtained by molding it. Can be manufactured. It is preferable to design the cover member 20 so that a predetermined clearance is generated between the cover member 20 and the electronic component 13 when the cover member 20 is pushed in. The clearance has a thickness at which the sealing resin material 30 is to be formed. Design based on standards. A cover member having a flat portion and a protruding portion protruding in a cylindrical shape from the flat portion as described above is also an aspect of the present invention.

  When the cover member 20 is pushed in, a jig (not shown) having an appropriate shape can be used. The jig is preferably configured so that the amount of pressing can be adjusted. When the housing 11 is provided with a concave portion or a convex portion for positioning, the pushing amount can be easily adjusted by using a jig having a corresponding shape. By comprising in this way, it can be used corresponding to the cover member 20 from which a kind differs.

According to the present invention, the cover member 20 preferably has a size sufficient to cover the housing 11, whereby the resin material 30 that flows when the cover member 20 is pushed deeply flows out of the housing 11 and the like. Can be prevented. As described above, when a concave portion or a convex portion for positioning is formed in the housing 11, the corresponding position of the cover member 20 is provided in a shape corresponding to the concave portion or the convex portion. Is preferred.
Further, according to the present invention, since the shape of the housing does not have to be complicated, the liquefied resin material is easy to flow inside the housing, and the resin material is uniformly filled around the electronic component, and the resin sealing Becomes more meaningful. There is no need to newly manufacture a specially shaped casing, and as long as an existing electronic circuit device has a cover member suitable for it, the present invention can be introduced without requiring a design change of the electronic circuit device itself. The amount of resin material used can be reduced.

  The cover member 20 has a hole formed by a cylindrical forming portion through which the resin material 30 can pass (penetrate). When the cover member 20 is used, the hole is formed in a region that covers the tallest electronic component 13. In FIG. 1 (D), the area | region where the cover member 20 does not exist on the tall electronic component 13 is represented, and these are holes. When the liquid surface of the resin material 30 is pushed by the cover member 20, air may be undesirably present between the resin material 30 and the electronic component 13, between the resin material 30 and the cover member 20, or the like. By pressing the cover member 20, air can be extracted from the hole. By pushing the cover member 20, the excess resin material 30 to be extruded flows out of the hole, so that the upper part of the tallest electronic component 13 can also be sealed with the resin material 30.

  The cover member 20 is preferably provided with a rib. The ribs are preferably formed in a lattice pattern on the cover member 20, whereby the strength of the cover member 20 can be improved. The example of the cover member 20 which has a rib in the below-mentioned Example is shown. The rib can also be used as a convex portion for positioning the cover member 20.

  Preferably, the cover member 20 is transparent. If the cover member 20 is transparent, the flow state of the introduced resin material 30 can be easily grasped by visual observation or other means through the cover member 20, so that improvement in workability and manufacturing quality is expected.

  As described above, the resin material 30 is cured while the cover member 20 is pushed in. The resin material 30 can be cured by an appropriate method such as heating or light irradiation according to the type of the resin material 30. During the curing, it is preferable to fix the cover member 20 in a pressed state by using a jig (not shown). By curing the resin material 30, an electronic circuit in which the cured resin material 30 is filled around the circuit board 12 and the electronic component 13 can be obtained. After the resin material 30 is cured, the cover member 20 may be removed or the cover member 20 may be left attached. The cured resin material 30 serves as a sealing member in the electronic circuit device. FIG. 1F is a schematic cross-sectional view of an electronic circuit device obtained by the manufacturing method of the present invention. In the embodiment of this figure, the cover member is removed after the resin material 30 is cured. As shown in the figure, in the region where the electronic component 13 is not mounted or the region where the short electronic component 13 is mounted, the resin material 30 is pushed down to a low position and cured, so that the tall electronic component 13 coexists. Even in such a case, use of a useless resin material can be suppressed, and cost reduction and weight reduction can be achieved. An electronic circuit device obtained by such a method is also an embodiment of the present invention. In this electronic circuit device, a standard height lower than that of the tallest electronic component 13 is assumed. This standard height is preferably a height that covers the top ends of the plurality of electronic components 13 that can be regarded as having substantially the same height. The sealing member made of the cured resin material 30 is provided at its standard height. Further, a sealing member covers the periphery and the top end portion of the electronic component 13 protruding from the standard height to constitute a protruding portion.

  Whether or not to remove the cover member 20 after the resin material 30 is cured can be arbitrarily determined depending on the application of the electronic circuit device to be manufactured. When the cover member 20 is removed after the resin material 30 is cured, the cover member 20 may be made of a material having a good releasability with respect to the resin material 30 to be used. For example, for many types of resin materials such as urethane resins and epoxy resins, excellent release properties can be obtained by configuring the cover member 20 with a silicone material. Alternatively, excellent releasability can also be obtained by using a urethane-based resin as the resin material 30 and making the cover member 20 made of polypropylene.

  The cover member 20 may remain attached after the resin material 30 is cured. For example, by forming the cover member 20 from a metal material and leaving such a metal cover member 20 after the resin material 30 is cured, it is possible to contribute to improving the strength of the obtained electronic circuit device.

  The material of the cover member 20 is not limited to the above-described silicone-based materials and metal materials, and various organic resin materials such as ceramic materials and polypropylene, composite materials such as glass epoxy, and the like can be used without particular limitation.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the embodiments described in these examples.

(Cover member)
A polypropylene cover material 20 having a thickness of 1.0 mm was formed by vacuum molding. The dimension was 148 mm × 123 mm, and the portion corresponding to the area where the electronic component 13 was not mounted was processed to a flatness of 4.5 mm deep. A portion corresponding to a region where the tall electronic component 13 is mounted was processed into a cylindrical shape having a depth of 3.5 mm, and a hole slightly larger than the electronic component 13 was formed. The cover member was provided with ribs at positions that were equally divided into 3 parts in the vertical and horizontal directions to improve the strength.

(Circuit boards and electronic components)
The dimensions of the circuit board 12 were 130 mm × 120 mm and the height was 1.6 mm. As the tall electronic component 13, an electrolytic capacitor (height 10.5 mm), a transformer (height 7.6 mm), and a connector (6.6 mm) were arranged. In addition, a short electronic component 13 was disposed. The tallest electronic component 13 among the short electronic components 13 was a coil (3.7 mm in height).

(Casing)
A rectangular parallelepiped housing 11 having an inner dimension of 150 mm × 125 mm and a height of 18 mm and having an open top was made of a 2 mm thick Noryl material.

(Introduction of resin materials)
A urethane-based resin having a viscosity of 700 to 1500 mPa · s (SU-2180AB, manufactured by Sanyu Rec Co., Ltd.) was introduced into the housing using a resin-filled nozzle.

(Pushing with cover member, curing of resin material)
After introducing the resin material, the liquid surface of the resin material was covered with a cover member, and the cover member was further pressed with a pressing jig. FIG. 2A is a plan view showing the arrangement of the electronic components 13 in the housing in the embodiment, and FIG. 2B is a cross-sectional perspective view thereof. The pressing jig 40 was pressed until the cover member 20 hits the wall of the casing 11. Note that in FIG. 2A, the depiction of the pushing jig is omitted. As described above, the cover member 20 is processed to a depth of 4.5 mm or 3.5 mm. When the resin material 30 is pressed, the resin material 30 wraps around the tall electronic component 13. It came to. As described above, the cover member 20 has the ribs 21 formed in both the vertical and horizontal directions. When the resin material 30 is pressed, the excess resin material 30 flows out from the hole formed in the cover member 20, and the resin material 30 is also covered above the tallest electronic component 13 (electrolytic capacitor). . In this state, the resin material 30 was cured by placing it in a furnace for 1 to 3 hours.

(Removal of cover member)
After the resin material 30 was cured, the load applied by the pressing jig 40 was released, and the cover member 20 was removed to obtain an electronic circuit device. All the electronic components 30 were completely sealed with the resin material 30. The amount of resin material introduced in this example was 190 g.

[Comparative Example 1]
An electronic circuit device was manufactured using the same casing, circuit board, electronic component, and resin material as in Example 1. However, the resin material was introduced to a height at which the tallest electronic component (electrolytic capacitor) was completely buried without using a cover member. That is, a resin material having a height (thickness) sufficient to completely bury the electrolytic capacitor has been introduced even in a region where no electronic component is present on the circuit board or a region where a short electronic component is mounted. After the introduction of the resin material, the resin material was cured to obtain an electronic circuit device. The amount of resin material introduced at this time was 250 g.

  As described above, in Example 1, compared with the case of Comparative Example 1, the resin material 30 introduced for manufacturing the electronic circuit device could be reduced by 24%.

  According to the present invention, even in an existing electronic circuit device, there is a possibility that the amount of the sealing resin used can be easily and significantly reduced without greatly changing the design, and the usefulness in the manufacture of the electronic circuit device is improved. It ’s big.

  11: Housing, 12: Circuit board, 13: Electronic component, 20: Sheet member, 21: Rib, 30: Resin material, 40: Pushing jig

Claims (6)

Introducing a liquefied resin material into the housing that houses the circuit board on which the electronic components are mounted,
Covering the surface of the introduced resin material with a cover member and pushing it in, partially pushing up the resin material and then curing the resin material,
The cover member is formed so as to cover the circuit board on which the electronic component is mounted, and has a hole through which the liquefied resin material can pass at a position corresponding to the tallest electronic component mounted on the circuit board. The resin material liquefied by pushing the surface of the resin material with the cover member seals the electronic component, and the excess resin material flows out from the hole.
Said manufacturing method.   The manufacturing method according to claim 1, wherein a height of the tallest electronic component is lower than a height of a wall portion of the housing.   The manufacturing method according to claim 1, wherein the cover member is removed after the resin material is cured.   The manufacturing method according to claim 1, wherein the cover member has ribs arranged in a lattice shape. A circuit board on which a plurality of electronic components having different heights are mounted, and a sealing member made of a resin material covering the electronic components,
The standard height of the sealing member from the circuit board is lower than the tallest electronic component mounted on the circuit board, and covers the height of the top of multiple electronic components that can be considered to have almost the same height. Is,
The sealing member extends so as to cover the periphery and the top end portion of the electronic component protruding from the standard height.
Electronic circuit device. A cover member that has a flat portion and a protruding portion that protrudes in a cylindrical shape from the flat portion, and is used when covering a circuit board on which an electronic component is mounted with a sealing member,
A tall electronic component mounted on the circuit board when the flat portion covering the height of the top of each of the plurality of electronic parts that can be regarded as being substantially equal in height is installed in parallel to the circuit board A cover member configured to cover the periphery of the protruding portion.

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