JP4995866B2 - Electronic component mounting structure and mounting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of an electronic component which has a simple structure of a mold, and holds down mold cost, and surely has insulation and prevents short circuit of lead, and to provide a method for mounting the electronic component. <P>SOLUTION: The mounting structure includes the electronic component 14 which is covered with a rectangular case 12 and has a lead 16 projected outside from the case 12. The mounting structure includes: a heat sink 18 which is attached on one side surface of the case 12 of the electronic component 14; and a mold part 28 which is attached on the heat sink 18 and is molded with insulating resin covering a part of the lead 16 on the side surface on which the electronic component 14 of the heat sink 18 is attached. The lead 16 of the electronic component 14 which is projected from the mold part 28 is connected to a printed board 24, and at the same time, the mold part 28 is made in contact with the printed board 24. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an electronic component mounting structure in which an insulating resin is mounted between terminals of an electronic component, and a mounting method thereof.

  Conventionally, in a power supply device, etc., where a heat sink is attached to an electronic component such as a power transistor and the outside air is blown by a cooling fan to radiate the electronic component, dust or the like contained in the outside air causes the electronic component lead or the lead to be soldered. If it accumulates on the attached printed circuit board or the like and absorbs moisture to become conductive, a short circuit accident may occur between the leads, which may cause a failure. In addition, conductive dust such as metal scrap may fly and cause a short circuit.

  In order to prevent such a short circuit, conventionally, there is a structure in which the whole is molded with an insulating resin while the electronic component and the heat sink are attached to each other. Alternatively, there is a method in which only the lead of the electronic component is molded with an insulating resin before the electronic component is attached to the heat sink and then attached to the heat sink.

  For example, the composite semiconductor devices disclosed in Patent Documents 1 and 2 disclose a structure in which only a lead is molded and an electronic component such as a semiconductor element is attached to a heat sink. In this structure, an electronic component such as a semiconductor chip is mounted on a conductor pattern, and an insulating substrate that constitutes a predetermined electric circuit, a heat sink that mounts the insulating substrate, and the heat sink is covered with the insulating substrate. An insulating case is provided. The side wall of the insulating case is insert-molded with a lead whose lower end is fixed to the conductor pattern of the insulating substrate and whose other end is led out to the outside of the insulating case.

  As another structure, there is a structure in which a tubular spacer is attached to the lead. Further, the electronic component short-circuit prevention spacer disclosed in Patent Document 3 is formed with an attachment portion which is a space for fitting the electronic component, and a plurality of insertions for inserting each lead of the electronic component into the bottom surface of the attachment portion. Mouth is provided. In the method of using this short-circuit prevention spacer, an electronic component is put in the adherend portion of the spacer body, and the lead is projected from the insertion opening. Then, the lead protruding from the spacer is soldered to the substrate on which the electronic component is mounted.

  Other methods include covering the entire electronic component with an insulating cap or coating the electronic component.

JP-A-11-177017 JP 2003-168766 A JP 2007-220963 A

  In the case of molding the entire electronic component and the heat sink with the insulating resin according to the above background art, there is a problem that at least a pair of molds for molding is required, and the entire structure becomes large and costs increase. Furthermore, since the volume of the molding material is increased, the molding material cost is increased, and it is necessary to provide an extra fixing function due to an increase in weight. Moreover, the heat dissipation of a heat sink will worsen and another heat dissipation structure will be needed.

  As in Patent Documents 1 and 2, the method of attaching the leads to the heat sink after molding the leads also requires a complicated mold for molding and increases the number of processes. Further, when molding the periphery of the lead, a die for that purpose is also required, which causes an increase in cost. In addition, since the electronic component is mounted on the heat sink after being molded, a highly accurate mold is required so that the insulating resin does not adhere to the mounting surface in contact with the heat sink.

  Also, if the insulating resin is in close contact with the printed circuit board, when the lead of the electronic component is inserted into the lead insertion hole of the printed circuit board and soldered to the back surface, the generated gas will clear the gap between the lead insertion hole and the lead. There is a problem that it cannot pass through, does not come out to the electronic component side of the printed circuit board, and a hole is formed in the solder, thereby impairing reliability.

  In addition, in a structure in which a tube-shaped spacer is mounted or a structure using insulating paper or the like, a gap is formed between the printed circuit board and the spacer or insulating paper, and the effect of closing the gap may be reduced.

  Furthermore, the coating method is difficult to apply and may cause uneven coating. In addition, when the parts subjected to the coating treatment are arranged in the vicinity of the air cooling fan, there is a problem that the effect of fine particles or moisture is strong with the sucked air because the wind speed is high, the coating film is boiled and the effect is lost. .

  The present invention has been made in view of the above-mentioned problems of the background art. The mold structure is simple, the mold cost can be suppressed, and it is surely insulative and prevents shorting of leads. It is an object of the present invention to provide an electronic component mounting structure and a mounting method thereof.

The present invention includes an electronic component lead from the case is covered by a rectangular casing protrudes outward, the attached heat radiating plate on one side of the casing of the electronic component, the mold for molding the heat radiating plate A molded part molded as a part, and a molded part formed of an insulating resin covering a part of the leads on a side surface of the heat radiating plate attached to the electronic component. A side surface of the heat radiating plate that is in contact with the electronic component, and a through hole communicating with the space of the molding die that is filled with the insulating resin when the molding die is attached to the heat radiating plate. hole is provided, made the insulating resin by molding is also filled in the through-hole, together with the the lead of the electronic component protruding from the mold portion is connected to the printed circuit board, wherein the mold portion is the pre Doo substrate is a mounting structure for an electronic component comprising contact.

  The lead of the electronic component protrudes outward from the bottom surface of the mold part, the lead of the electronic component is inserted into the lead insertion hole of the printed circuit board and protrudes to the opposite side and soldered, and the bottom surface of the mold part Is in contact with the printed circuit board, and the bottom surface of the mold part is provided with a groove part through which the lead part protrudes, and the groove part is in contact with the heat sink and the printed circuit board of the mold part. It communicates with either side and is open to the outside air.

According to the present invention, an electronic component covered with a rectangular case and having a lead projecting outward from the case is fixed to one side surface of the heat radiating plate, and a part of the lead is covered on the side surface of the heat radiating plate. mounting and sealing the molding die to cover at least a portion of the component, the the forming mold by injecting an insulating resin molding the molded part, the mold portions and thereafter the heat radiating plate is attached the An electronic component mounting method for connecting a lead of an electronic component to a printed circuit board.

  The electronic component mounting structure and the mounting method according to the present invention have a simple mold structure, can reduce the cost of the mold, can reliably have insulation, and can prevent a short circuit between leads. Further, the lead can be surely soldered to the printed circuit board.

It is the front view (a) and right view (b) of the attachment structure of the electronic component of one Embodiment of this invention. It is a partial expanded front view of the attachment structure of the electronic component of this embodiment. It is a right view which shows the attachment structure of the electronic component of this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 show an embodiment of the present invention. An electronic component mounting structure 10 according to this embodiment includes an electronic component 14 covered with a rectangular case 12, and is provided on a bottom surface 12 a of the case 12. A plurality of leads 16 are provided so as to protrude substantially perpendicular to the bottom surface 12a.

  A heat radiating plate 18 made of a metal plate is fixed to the side surface 12 b of the electronic component 14 that intersects the bottom surface 12 a of the case 12 with screws 20. The heat radiating plate 18 is made of a material with good heat dissipation, and is made of, for example, aluminum with good heat conductivity. A through hole 22 is provided on a side surface 18 a of the heat radiating plate 18 that is in contact with the electronic component 14 at a position that communicates with the space 37 of the mold 36 when a mold 36 described later is attached to the heat radiating plate 18. Yes. The through hole 22 passes through the side surface 18a of the heat radiating plate 18 and the side surface 18b on the opposite side.

  A rectangular mold portion 28 is provided on a side surface 18a of the heat radiating plate 18 to which the electronic component 14 is attached. The mold part 28 is a rectangular block body made of an insulating resin, and is molded of a thermoplastic resin such as polyamide or polyester. The mold part 28 is attached so as to cover a part of the lead from the vicinity of the end of the electronic component 14 on the lead 16 side, and a part of the case 12 of the electronic part 14 protrudes from the upper surface 28 a of the mold part 28. The lead 16 protrudes downward from the bottom surface 28b opposite to the top surface 28a. The bottom surface 28b is provided with a groove 30 that passes through a portion where the lead 16 protrudes. The groove portion 30 communicates with any side surface of the mold portion 28 that is not in contact with the heat radiating plate 18 and is opened to the outside air. The through hole 22 of the heat sink 18 is opposed to the side surface 28c of the mold portion 28 that contacts the heat sink 18 and the insulating resin is continuously filled in the through hole 22 to reach the side surface 18b of the heat sink 18 and the side surface 18b. And a flange portion 32 is formed.

  The electronic component 14, the heat dissipation plate 18, and the mold part 28 are attached to the printed circuit board 24 in a state of being attached to each other. A lead insertion hole 26 through which the lead 16 of the electronic component 14 is inserted is formed at a predetermined position of the printed circuit board 24. An end face 18 c of the heat sink 18 near the lead 16 of the electronic component 14 abuts on the printed circuit board 24, and the lead 16 of the electronic component 14 is inserted into the lead insertion hole 26 of the printed circuit board 24 and on the opposite side of the printed circuit board 24. It protrudes and is connected by solder 34.

Next, a method for assembling and attaching the electronic component will be described with reference to FIG. First, the electronic component 14 is brought into contact with the side surface 18 a of the heat radiating plate 18 and fixed with screws 20. Thereafter, the side surface 18a of the heat radiating plate 18, attaching the molding die 36 for molding the molded part 28.

Here will be described a molding die 36. Molding die 36 is made of aluminum with good good heat dissipation heat conductivity, and three sides 36a surrounding a side surface 18a of the heat sink 18 to a U-shape in the horizontal direction, and the upper surface 36b which covers the upper portion, It is formed with a bottom surface 36c covering the lower part. The inner side surrounded by the three side surfaces 36a, the upper surface 36b, and the bottom surface 36c becomes a space portion 37 that is filled with an insulating resin and molds the mold portion 28. Moreover, the part facing the side surface 18a is opened. The upper surface 36b of the molding die 36, the recess 38 of the case 12 is fitted in the electronic part 14 is formed in communication with the contacting openings on the side surface 18a. The bottom surface 36c of the molding die 36, through opening 40 is formed which leads 16 of the electronic component 14 is inserted. On the surface of the bottom surface 36 c facing the top surface 36 b, that is, on the inner peripheral surface of the space portion 37, a protrusion 42 is integrally formed at a position including the insertion port 40. Projection 42 is a negative shape of the recess 38 of the mold portion 28, a bottom surface 36c of the molding die 36 is formed so as to cross between any other aspects. Here, it has reached the side surface 36a located on the opposite side to the opening.

Then, when molding the molded part 28, the molding die 36, it is brought into contact with the side surface 18a of the heat radiating plate 18 which is also used in the other die. The recess 38 of the upper surface 36b of the molding die 36 is fitted to the case 12 of the electronic component 14, the insertion hole 40 of the bottom surface 36c inserting the leads 16 of the electronic component 14. The bottom surface 36c is set so that the surface facing the top surface 36b is substantially flush with the end surface 18c of the heat radiating plate 18 and there is no gap. In this state, the through holes 22 of the heat radiating plate 18 communicates with the space portion 37 of the molding die 36.

Then, the insulating resin heated and melted from the side surface 18b side is press-fitted into the through hole 22 of the heat radiating plate 18, filled in the space 37, cooled and molded. A method of press-fitting the heat-insulated insulating resin is low-pressure injection molding or the like. Then, after the mold section 28 inside the space 37 is cooled to a predetermined temperature is formed, removing the molding die 36. The electronic component 14, the heat sink 18, and the mold portion 28 are attached to each other, and the lead 16 of the electronic component 14 is inserted into the lead insertion hole 26 of the printed circuit board 24 and protrudes from the opposite side of the printed circuit board 24. Is fixed with solder 34. At this time, the gas generated by the heat of the solder 34 can pass through the gap between the lead insertion hole 26 and the lead 16, escape to the opposite side surface, and escape from the groove 30. Thereby, it is possible to prevent the solder from being perforated.

According to the mounting structure 10 of the electronic component of this embodiment, since also serves as a heat radiating plate 18 on one of the mold, that insulation in molding die 36 of the first member is molded with high molding portion 28 It is possible to suppress the mold cost and reliably prevent the lead 16 from being short-circuited. Since the groove portion 30 is provided on the bottom surface 28 b of the mold portion 28, the gas generated by the heat of the solder 34 can pass through the gap between the lead insertion hole 26 and the lead 16 and escape from the groove portion 30. Can prevent perforation and improve reliability. And between the adjacent leads 16, since the bottom face 28b of the mold part 28 contacts the printed circuit board 24 and the electronic component 14 is mounted, a short circuit between the leads 16 can be surely prevented.

Furthermore, since the mold part 28 is formed after the electronic component 14 is attached to the heat radiating plate 18, it is not necessary to manage such that the insulating resin does not adhere to the side surface 12 b of the case 12 of the electronic component 14 attached to the heat radiating plate 18. , the working process is facilitated, may not have high molding die accuracy. In the mold part 28, the insulating resin is continuously integrated with the through hole 22 and the flange part 32 of the heat radiating plate 18, and is securely attached to the heat radiating plate 18, and does not come off.

Incidentally, the mounting structure and the mounting method of the electronic component of the present invention is not limited to the embodiment described above, without providing a through hole in the heat sink may be injected resin from the molding die side . Further, the mold used may be divided into a plurality of molds. Further, the shape and material of the mold part and the like can be appropriately changed. The cross-sectional shape of the groove portion may be various shapes other than the semicircular shape, and it is only necessary that the direction in which the groove portion passes is reliably opened to the outside air. The shape and position of the through hole into which the insulating resin is injected can be freely changed, and may be a notch.

10 electronic component mounting structure 12 Case 14 electronic component 16 leads 18 radiating plate 20 screw 22 through hole 24 printed circuit board 26 lead insertion hole 28 mold section 30 groove 32 flange portion 34 solder 36 molding die 37 a space 38 recess 40 through Mouth 42 protrusion

Claims (3)

An electronic component lead from the case is covered by a rectangular casing protrudes outwardly, and the heat radiating plate attached to one side of the casing of the electronic component, shaping the heat radiating plate as a part of a mold for molding a has been molded part, wherein attached to the heat radiating plate and a said heat radiating plate the electronic components molded portion molded with an insulating resin covering a portion of the lead on a side attached to the heat radiating plate The side surface in contact with the electronic component is provided with a through hole that communicates with the space of the molding die that is filled with the insulating resin when the molding die is attached to the heat sink. become the insulating resin by molding is also filled in the through-hole, together with the leads of the electronic component protruding from the mold portion is connected to the printed circuit board, wherein the mold portion to the printed circuit board those Mounting structure of an electronic component, characterized in that formed by.   The lead of the electronic component protrudes outward from the bottom surface of the mold part, the lead of the electronic component is inserted into the lead insertion hole of the printed circuit board and protrudes to the opposite side and soldered, and the bottom surface of the mold part Is in contact with the printed circuit board, and the bottom surface of the mold part is provided with a groove part through which the lead part protrudes, and the groove part is in contact with the heat sink and the printed circuit board of the mold part. The electronic component mounting structure according to claim 1, wherein the electronic component mounting structure is open to the outside air in communication with any one of the side surfaces. An electronic component covered with a rectangular case and having a lead projecting outward from the case is fixed to one side surface of the heat radiating plate, and the side surface of the heat radiating plate covers a part of the lead and at least a part of the electronic component. mounting and sealing the molding die covering the the forming mold by injecting an insulating resin molding the molded part, the leads of the electronic component the mold part and thereafter the heat radiating plate is attached An electronic component mounting method comprising connecting to a printed circuit board.

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