JP2020155663A - Insert molding component and electronic apparatus - Google Patents

Abstract

To prevent conductive foreign matter from being generated in an insert molded component.SOLUTION: An insert molded component 1 provided in an electronic apparatus is constituted of: a metal member 3 in which a metal plating 4 is applied onto the surface; and a synthetic resin 2 covering the metal member 3 and integrated with the metal member 3. In the metal member 3, a through-hole 3h is formed, which is for positioning the metal member 3 during insert molding. In a portion consisting of the synthetic resin 2 located on one side of the depth direction of the through-hole 3h, a through-hole 2h is formed so as to communicate with the through-hole 3h. In the portion consisting of the synthetic resin 2 located on the other side in the depth direction of the through hole 3h, a through- hole 2j is formed so as to communicate with the through-hole 3h. Diameters of through-holes 2h, 2j are larger than that of the through hole-3h, and a peripheral edge part 3s of the through-hole 3h protrudes closer to the center side of the through-hole 3h than the inner peripheral surfaces 2f, 2g of the through-holes 2h, 2j.SELECTED DRAWING: Figure 3

Description

The present invention relates to an insert molded part formed by insert molding and an electronic device provided with the insert molded part.

A molding method in which a synthetic resin is injected around a metal member loaded in a mold to integrate the metal member and the synthetic resin is called insert molding. Some electronic devices include insert-molded parts formed by such insert molding.

The surface of the metal member of the insert molded part is metal-plated to prevent rust and corrosion. When the metal member is a conductor that functions as wiring for a bus bar or the like, a connection portion that is electrically connected to the metal member to a conductor such as a terminal or wiring of another electronic component provided in an electronic device. Is formed. Electrical connection methods between the connection portion of the metal member and other conductors include soldering, welding, and thermocompression bonding.

As another electronic component in which a conductor functioning as a wiring is covered with a synthetic resin (insulator), for example, there is a circuit board disclosed in Patent Documents 1 to 4. In these circuit boards, the upper surface, lower surface, or side surface of the conductor (bus bar) is covered with synthetic resin. Then, in order to solder the pin-shaped terminals of the electronic component to the conductor of the circuit board, a through hole is formed in the conductor. Further, a through hole is also formed in a portion of the circuit board made of synthetic resin so that peripheral portions on one side or both sides in the depth direction of the through hole of the conductor are exposed. The through hole of the portion made of synthetic resin is formed with a diameter larger than that of the conductor and communicates with the through hole of the conductor. The terminals are soldered to the inner peripheral surface and the peripheral edge of the through hole of the conductor in a state of being inserted into the through hole of the portion made of synthetic resin and the through hole of the conductor.

Japanese Patent No. 4337685 Japanese Unexamined Patent Publication No. 10-321985 Japanese Unexamined Patent Publication No. 2011-166874 Japanese Unexamined Patent Publication No. 2016-149466

FIG. 5 is a cross-sectional view of a main part of the conventional insert molded part 50. As shown in FIG. 5A, a through hole 53h is formed in the metal member 53 embedded in the synthetic resin 52 of the insert molded part 50. The through hole 53h is for positioning the metal member 53 in the mold during insert molding of the insert molded part 50. At the time of insert molding, a positioning member (not shown) such as a pilot pin is inserted into the through hole 53h. Then, the synthetic resin 52 does not spread to the portion of the mold where the positioning member exists. Therefore, through holes 52h and 52j communicating with the through holes 53h of the metal member 53 are formed in the portion of the molded insert molded part 50 made of the synthetic resin 52. Then, the inner peripheral surface 53f of the through hole 53h of the metal member 53 is exposed from the inner peripheral surfaces 52f and 52g of the through holes 52h and 52j of the portion made of the synthetic resin 52.

For example, when another conductor (not shown) is electrically connected to the connection portion (not shown) of the metal member 53 by soldering or the like, the metal member 53 is heated and the temperature of the metal member 53 is increased. Will be higher. Further, when the conductors in the vicinity of the metal member 53 are electrically connected to each other, the metal member 53 is indirectly heated and the temperature of the metal member 53 rises. Then, when the temperature of the metal member 53 exceeds the melting point of the metal plating 54 applied to the surface of the metal member 53, the metal plating 54 melts. In particular, when tin plating having a relatively low melting point is applied to the surface of the metal member 53 and another conductor is soldered to the connection portion of the metal member 53 with lead-free solder having a relatively high melting point, the metal member 53 The temperature of the tin plating exceeds the melting point of the tin plating, and the tin plating on the surface of the metal member 53 tends to melt.

As shown in FIG. 5B, when the metal plating 54 is melted at or near the inner peripheral surface 53f of the through hole 53h of the metal member 53, and then when the temperature of the metal member 53 drops, the metal plating The melts of 54 aggregate to form a solidified product 54'. In the conventional insert molded part 50, the diameter of the through hole 53h of the metal member 53 and the diameter of the through holes 52h and 52j of the portion made of the synthetic resin 52 are the same, and the inner peripheral surface 53f of the through hole 53h and the inner peripheral surface 53f. The inner peripheral surfaces 52f and 52g of the through holes 52h and 52j are flush with each other. Therefore, the solidified material 54'of the metal plating 54 is easily peeled off from the inner peripheral surface 53f of the through hole 53h of the metal member 53 to become a granular conductive foreign matter 54 ". This conductive foreign matter 54" is inserted. If it falls on a portion of an electronic device including a molded component 50 that constitutes an electric circuit, there is a risk of causing a problem such as a short circuit at that portion.

An object of the present invention is to prevent the generation of conductive foreign matter in an insert molded part.

The insert-molded part of the present invention is a molded part composed of a metal member whose surface is metal-plated and a synthetic resin that covers the metal member and is integrated with the metal member. It is formed in a portion made of a first through hole for positioning the metal member at the time of insert molding and a synthetic resin on one side in the depth direction of the first through hole so as to communicate with the first through hole. The second through hole is provided with a third through hole formed in a portion made of synthetic resin on the other side in the depth direction of the first through hole so as to communicate with the first through hole. The diameters of the second through hole and the third through hole are larger than the diameter of the first through hole, and the peripheral edge of the first through hole in the metal member is first from the inner peripheral surfaces of the second through hole and the third through hole. It protrudes toward the center of the through hole.

Further, the electronic device of the present invention includes the insert-molded component and an electronic component electrically connected to a metal member provided on the insert-molded component.

According to the above, since the peripheral edge of the first through hole of the metal member protrudes from the inner peripheral surface of the second through hole and the inner peripheral surface of the third through hole, the second through hole side and the second through hole of the peripheral portion An exposed surface is formed on each of the three through holes. Therefore, when the temperature of the metal member exceeds the melting point of the metal plating on the surface and the metal plating at or near the peripheral portion of the first through hole of the metal member melts, the temperature of the metal member subsequently decreases. , The molten metal plating aggregates on the exposed surface to form a solidified product. Then, since the solidified metal plating does not peel off from the metal member, it is possible to prevent the generation of conductive foreign matter that may cause a short circuit or the like in the portion constituting the electric circuit in the electronic device.

In the present invention, the inner peripheral surface of the second through hole of the insert molded part is in contact with the exposed surface of the peripheral edge of the first through hole on the second through hole side perpendicularly to the inner peripheral surface of the third through hole. However, the peripheral portion of the peripheral portion of the first through hole may be in contact with the exposed surface on the third through hole side perpendicularly.

Further, in the present invention, the metal member of the insert molded part may have a connecting portion that is electrically connected to another conductor.

Further, in the present invention, the metal plating of the metal member of the insert molded part is made of tin plating, and the connecting portion may be soldered to another conductor with lead-free solder.

Further, in the present invention, the electronic device may further include a metal member of the insert molded component or a substrate electrically connected to the electronic component.

According to the present invention, it is possible to prevent the generation of conductive foreign matter in the insert molded part.

It is a perspective view of the main part of the electronic device by embodiment of this invention. It is an enlarged view of the periphery of the insert molded part of FIG. It is a figure which showed the AA cross section of FIG. It is sectional drawing which showed the formation example of the through hole of FIG. It is sectional drawing of the main part of the conventional insert molded part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same parts or corresponding parts are designated by the same reference numerals.

FIG. 1 is a perspective view of a main part of the electronic device 100 according to the embodiment. FIG. 2 is an enlarged view of the periphery of the insert molded part 1 of FIG.

The electronic device 100 shown in FIG. 1 is, for example, an in-vehicle DC-DC converter, and is installed near the engine of the vehicle. The electronic device 100 includes an insert molded component 1, an electrolytic capacitor 5, a coil component 6, substrates 7, 8 and a base 9.

The substrates 7 and 8 are made of a printed circuit board or a metal substrate. The boards 7 and 8 are provided with electronic components, electric circuits, wiring patterns, and terminals 71 and 81 that form a DC-DC converter. In the substrates 7 and 8 of FIGS. 1 and 2, components other than the terminals 71 and 81 are not shown. The terminals 71 and 81 are made of conductors and are mounted on the upper surfaces of the substrates 7 and 8 with lead-free solder.

Each of the substrates 7 and 8 has a plurality of screws 10a and 10b penetrated through a plurality of through holes (not shown) formed in the respective substrates 7 and 8, and then a plurality of corresponding screw holes (not shown) formed in the base 9. It is fixed on the base 9 by screwing into each of them (not shown). Although the base 9 is made of metal in this example, it may be made of another material such as synthetic resin.

The coil component 6 is made of a choke coil. The coil component 6 includes terminals 61 and 62, a coil 63, a holder 64, a core 65, and the like. The terminals 61 and 62 are integrally formed with the coil 63 at both ends of the coil 63, respectively. The terminals 61 and 62 and the coil 63 are formed flat by processing a sheet metal.

The coil 63 is wound around a convex portion (not shown) provided in the center of the core 65 in a state of being housed in a holder 64 made of synthetic resin. The holder 64 is formed by passing a plurality of screws 10c through a plurality of through holes (not shown) formed in the holder 64 and screwing them into corresponding screw holes (not shown) formed in the base 9. It is fixed on 9.

The terminals 61 and 62 are made of conductors and project from the holder 64. The terminal 61 formed at one end of the coil 63 is electrically connected to the terminal 71 mounted on the substrate 7 by soldering or welding with lead-free solder.

The core 65 is made of a magnetic material. The leaf spring 11 is engaged with the core 65 from above, and the screws 10d are passed through the through holes (not shown) formed at both ends of the leaf spring 11, and a plurality of the screws 10d are formed on the base 9. Screw into the screw hole (not shown). As a result, the core 65 is fixed on the base 9 in a state of being pressed against the base 9 by the leaf spring 11.

The insert molded part 1 is formed by insert molding in which the synthetic resin 2 is injected around the metal member 3 loaded in the mold (not shown) to integrate the metal member 3 and the synthetic resin 2. That is, the insert molded part 1 is composed of a metal member 3 and a synthetic resin 2 that covers the metal member 3 and is integrated with the metal member 3.

The insert-molded part 1 is formed with a box-shaped accommodating portion 1a and a flange portion 1b (FIG. 2) protruding laterally from the lower portion of the accommodating portion 1a. The accommodating portion 1a is entirely made of synthetic resin 2. The collar portion 1b is composed of a synthetic resin 2 and a metal member 3 embedded in a part thereof (FIG. 2).

In the insert molded part 1, a plurality of screws 10e are passed through a plurality of through holes (not shown) formed in the flange portion 1b, and then a plurality of corresponding screw holes (not shown) are formed in the base 9. It is fixed on the base 9 by screwing.

A plurality of electrolytic capacitors 5 are housed in the housing portion 1a of the insert molded part 1. The electrolytic capacitor 5 is a through-hole mounting type electronic component.

Each electrolytic capacitor 5 is provided with a lead terminal (not shown) made of a conductor. The lead terminals are a plurality of through holes (not shown) formed in the bottom wall (not shown) of the accommodating portion 1a and a plurality of through holes (not shown) formed in the substrate 8 so as to be located below the through holes. (Omitted) and penetrate each. Then, each lead terminal is soldered to each through hole by lead-free solder. That is, each electrolytic capacitor 5 is electrically connected to the substrate 8.

As shown in FIG. 2, a bent metal member 3 is provided in a part of the flange portion 1b of the insert molded part 1. The metal member 3 is embedded in the synthetic resin 2 except for both ends.

The metal member 3 is made of a conductor such as copper and functions as a bus bar. Therefore, connecting portions 3a and 3b are formed at both ends of the metal member 3, respectively. One of the connecting portions 3a projects upward from the upper surface of the flange portion 1b. The other connecting portion 3b is bent so as to project upward from the side surface of the flange portion 1b and then extend upward.

One connection portion 3a is electrically connected to the terminal 62 of the coil 63 of the coil component 6 (FIG. 1) by soldering or welding with lead-free solder. The other connecting portion 3b is electrically connected to the terminal 81 mounted on the substrate 8 by the same means. Further, as described above, the terminal 61 of the coil 63 is electrically connected to the terminal 71 mounted on the substrate 7 by the same means. That is, the substrate 7, the coil component 6, the metal member 3 of the insert molded component 1, and the substrate 8 are electrically connected. The coil component 6 and the substrates 7 and 8 are examples of the "electronic component" of the present invention.

Through holes 1h and 1j are formed in the vicinity of the connecting portions 3a and 3b so as to penetrate the portion where the metal member 3 of the flange portion 1b is embedded. Nothing is inserted into these through holes 1h and 1j.

FIG. 3 is a view showing a cross section taken along the line AA across the through hole 1h of FIG. Since the structures of the through hole 1h and the through hole 1j are similar, the BB cross section crossing the through hole 1j in FIG. 2 is the same as the AA cross section. Therefore, although the illustration of the BB cross section and the description of the through hole 1j are omitted, the following description also applies to the through hole 1j.

As shown in FIG. 3A, the through holes 1h and 1j of the insert molded part 1 are formed from the through holes 3h formed in the metal member 3 and the synthetic resin 2 on one side of the through holes 3h in the depth direction. It is composed of a through hole 2h formed in the portion made of the synthetic resin 2 and a through hole 2j formed in the portion made of the synthetic resin 2 on the other side of the through hole 3h in the depth direction. The through holes 2h and 2j of the portion made of the synthetic resin 2 communicate with the through holes 3h of the metal member 3.

The through hole 3h of the metal member 3 is for positioning the metal member 3 in the mold at the time of insert molding of the insert molded part 1. The entire surface of the metal member 3 is subjected to metal plating 4 such as tin plating for corrosion prevention and rust prevention.

FIG. 4 is a cross-sectional view showing an example of forming the through hole 1h at the time of insert molding of the insert molded part 1.

First, as shown in FIG. 4A, the metal member 3 in which the metal plating 4 is applied to the entire surface and the through hole 3h for positioning is formed is formed in the pair of molds 18 and 19 for insert molding. Load in place. At this time, the pilot pins (positioning members) 18a and 19a provided on the molds 18 and 19 so as to appear and disappear face the through holes 3h.

The pilot pins 18a and 19a are formed in a columnar shape. The tip of the pilot pin 18a provided on one of the molds 18 is formed in a convex shape. The diameter of the convex portion 18b of the pilot pin 18a is equal to or slightly smaller than the diameter of the through hole 3h of the metal member 3. The tip of the pilot pin 19a provided on the other mold 19 is formed in a concave shape. The diameter of the concave portion 19b of the pilot pin 19a is equal to or slightly larger than the diameter of the convex portion 18b.

Next, as shown in FIG. 4B, the pilot pin 18a is projected downward from one of the molds 18, and the convex portion 18b at the tip of the pilot pin 18a is penetrated through the through hole 3h of the metal member 3. The step portion 18c is engaged with one plate surface of the metal member 3. Further, the pilot pin 19a is projected upward from the other mold 19, the tip surface 19c of the pilot pin 19a is engaged with the other plate surface of the metal member 3, and the concave portion 19b and the convex portion 18b are engaged with each other. ..

Next, as shown in FIG. 4C, the melted synthetic resin 2 is filled in the molds 18 and 19. Then, after the synthetic resin 2 is cured to some extent, the pilot pins 18a and 19a are immersed in the molds 18 and 19 to remove the molds 18 and 19. As a result, the insert-molded part 1 is formed, and as shown in FIG. 3A, the flange portion 1b of the insert-molded part 1 penetrates the portion made of the synthetic resin 2, which is a trace of the pilot pins 18a and 19a. A through hole 1h composed of the holes 2h and 2j and the through hole 3h of the metal member 3 is formed.

The diameter of the through holes 2h and 2j of the portion made of the synthetic resin 2 is larger than the diameter of the through holes 3h of the metal member 3. Therefore, the peripheral edge portion 3s of the through hole 3h in the metal member 3 protrudes from the inner peripheral surfaces 2f and 2g of the through hole 2h and 2j toward the center side of the through hole 3h. Further, the inner peripheral surface 2f of the through hole 2h is in direct contact with the exposed surface 3t (upper surface) on the through hole 2h side of the peripheral portion 3s, and the inner peripheral surface 2g of the through hole 2j is the peripheral portion 3s. It is in contact with the exposed surface 3t (lower surface) on the through hole 2j side perpendicularly.

As described above, the metal member 3 is heated when the terminal 62 of the coil component 6 and the terminal 81 of the substrate 8 are electrically connected to the connection portions 3a and 3b of the metal member 3 by soldering or welding. Therefore, the temperature of the metal member 3 becomes high. Further, as described above, when the lead terminal of the electrolytic capacitor 5 in the vicinity of the metal member 3 is electrically connected to the through hole of the substrate 8, the metal member 3 is indirectly heated and the metal member 3 is heated. The temperature of the metal rises. Then, when the temperature of the metal member 3 exceeds the melting point of the metal plating 4 applied to the surface of the metal member 3, the metal plating 4 melts.

In particular, the metal plating 4 on the surface of the metal member 3 is made of tin plating having a relatively low melting point, and the other terminals 62 and 81 are made of lead-free solder having a relatively high melting point with respect to the connecting portions 3a and 3b of the metal member 3. When soldering with, the temperature of the metal member 3 exceeds the melting point of the tin plating, and the tin plating on the surface of the metal member 3 is likely to melt.

When the metal plating 4 is melted at or near the peripheral edge portion 3s protruding into the through hole 1h, the melt of the metal plating 4 is aggregated when the temperature of the metal member 3 is subsequently lowered, and FIG. As shown in b), it becomes a solidified product 4'.

However, according to the structure of the through hole 1h of the above-described embodiment, the peripheral edge portion 3s of the through hole 3h of the metal member 3 protrudes from the inner peripheral surfaces 2f and 2g of the through hole 2h and 2j, and the through hole 2h side ( Since the exposed surfaces 3t are provided on the upper side) and the through hole 2j side (lower side), the melt of the metal plating 4 generated on the peripheral edge portion 3s and the like is aggregated on the upper and lower exposed surfaces 3t of the peripheral edge portion 3s. Then, it becomes a solidified product 4'. Then, the solidified material 4'of the metal plating 4 is held by the exposed surface 3t and does not peel off from the metal member 3, so that it is possible to prevent the generation of granular conductive foreign matter based on the solidified material 4'of the metal plating 4. can do.

As a result, problems such as short circuits may occur due to conductive foreign matter in the parts constituting the electric circuit in the electronic device 100, such as the coil 63 of the coil component 6 and the wiring patterns formed on the substrates 7 and 8. It can be prevented in advance.

Further, in the above-described embodiment, the inner peripheral surfaces 2f and 2g of the through holes 2h and 2j of the portion made of the synthetic resin 2 are in contact with the upper and lower exposed surfaces 3t of the peripheral edge portion 3s perpendicularly. Therefore, the melt of the metal plating 4 aggregates in the vicinity of the corner portion C where the upper and lower exposed surfaces 3t of the peripheral edge portion 3s and the inner peripheral surfaces 2f and 2g of the through holes 2h and 2j are in contact with each other. It becomes easy to solidify. As a result, the solidified material 4'of the metal plating 4 is more difficult to peel off from the metal member 3, and the generation of conductive foreign matter based on the solidified material 4'of the metal plating 4 can be further suppressed.

Further, when the metal plating 4 is made of tin plating and the connection portions 3a and 3b of the metal member 3 and the other terminals 62 and 81 are soldered with lead-free solder, the temperature of the metal member 3 determines the melting point of the tin plating. Even if the amount of tin plating melted around the through hole 3h is larger than that, the melt can be aggregated in the vicinity of the exposed surface 3t and the corner portion C. As a result, the solidified product 4'in which the tin-plated melt is solidified can be reliably held by the exposed surface 3t or the corner portion C, and the generation of conductive foreign matter based on the solidified material 4'can be further suppressed.

In the present invention, various embodiments other than those described above can be adopted.

For example, in the above embodiment, an example in which only one metal member 3 is provided on the insert molded part 1 is shown, but the present invention is not limited to this. A plurality of metal members 3 may be provided on the insert molded part 1. Further, the metal member 3 of the insert molded part 1 does not have to form a part of the electric circuit. Further, the insert molded part 1 may be provided with a metal member 3 that does not have connecting portions 3a and 3b that are electrically connected to other conductors. Further, the metal plating 4 applied to the surface of the metal member 3 may be other than tin plating.

Further, in the above embodiment, an example in which two positioning through holes 3h and 3j are provided in the metal member 3 of the insert molded part 1 is shown, but the present invention is not limited to this. The metal member 3 may be provided with one or three or more positioning through holes. Further, the through hole for positioning may have an arbitrary shape such as a circular shape, an elliptical shape, or a rectangular shape.

Further, in the above embodiment, the connection portions 3a and 3b of the metal member 3 of the insert molded component 1 are electrically connected to the terminal 62 provided on the coil component 6 and the terminal 81 mounted on the substrate 8, respectively. Although a connected example is shown, the present invention is not limited to this. The connecting portions 3a and 3b of the metal member 3 may be electrically connected to conductors provided in other electronic components. Further, as an electrical connection method between the connection portions 3a and 3b of the metal member 3 and other conductors, in addition to soldering and welding with lead-free solder, for example, soldering with eutectic solder and thermal pressure bonding, etc. Other connection methods may be adopted.

Further, in the above embodiment, an example in which the present invention is applied to an electronic device 100 composed of an in-vehicle DC-DC converter and an insert molded component 1 provided in the electronic device 100 has been given, but other in-vehicle devices have been given. It is possible to apply the present invention to electronic devices and insert-molded parts of the above, and electronic devices and insert-molded parts other than those for automobiles.

1 Insert molded part 2 Synthetic resin 2f, 2g Inner peripheral surface 2h Through hole (second through hole)
2j through hole (third through hole)
3 Metal member 3a, 3b Connection part 3h Through hole (first through hole)
3s Peripheral part 3t Exposed surface 4 Metal plating 6 Coil parts (electronic parts)
7 and 8 boards (electronic components)
62, 81 terminals (other conductors)
100 electronic devices

Claims (6)

Metal members with metal plating on the surface and
In an insert molded part composed of a synthetic resin that covers the metal member and is integrated with the metal member.
A first through hole formed in the metal member for positioning the metal member at the time of insert molding,
A second through hole formed in a portion made of the synthetic resin on one side in the depth direction of the first through hole so as to communicate with the first through hole.
A third through hole formed in a portion made of the synthetic resin on the other side in the depth direction of the first through hole so as to communicate with the first through hole is provided.
The diameters of the second through hole and the third through hole are larger than the diameter of the first through hole.
The peripheral portion of the first through hole in the metal member protrudes from the inner peripheral surfaces of the second through hole and the third through hole toward the center of the first through hole. parts. In the insert molded part according to claim 1,
The inner peripheral surface of the second through hole is in contact with the exposed surface of the peripheral portion on the second through hole side perpendicularly.
An insert molded part characterized in that the inner peripheral surface of the third through hole is in contact with the exposed surface of the peripheral portion on the third through hole side perpendicularly. In the insert molded part according to claim 1 or 2.
An insert molded part, characterized in that the metal member has a connecting portion that is electrically connected to another conductor. In the insert molded part according to claim 3,
The metal plating of the metal member comprises tin plating.
An insert-molded part characterized in that the connection portion is soldered to the other conductor with lead-free solder. The insert-molded part according to any one of claims 1 to 4,
An electronic device including an electronic component electrically connected to the metal member provided on the insert-molded component. In the electronic device according to claim 5,
An electronic device further comprising a substrate electrically connected to the metal member or the electronic component.

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