JP4795843B2 - Printed circuit board mounting product - Google Patents

Description

The present invention relates to a printed circuit board on which a transformer is mounted, and more particularly to a printed circuit board mounted product in which the surface of a printed circuit board on which electronic components are mounted is molded with a resin.

  Electronic components such as semiconductors are mounted on the surface of the printed board. Printed circuit boards on which electronic components are mounted are used for various purposes. In particular, it is used for applications with a lot of vibration such as in-vehicle use, and may be used in a high humidity environment. Therefore, the electronic component mounted on the printed circuit board is molded with a mold resin to prevent the occurrence of a poor electrical connection of the electronic component due to vibration, and the electronic component is not directly exposed to moisture.

  FIG. 3 is a cross-sectional view showing a printed circuit board mounted product 100 in which a transformer is mounted on a printed circuit board and molded with a mold resin. FIG. 3A is a cross-sectional view in one direction, and FIG. 3B is a cross-sectional view in the other direction. In FIG. 3, two transformers 101 a and 101 b are installed side by side on the printed circuit board 103. The surface of the printed circuit board 103 is covered with the mold resin 104, and the lower part than about 1/2 of the transformers 101a and 101b is filled with the mold resin 104. Other electronic parts not shown are completely covered with the mold resin 104.

The transformer 101a or 101b includes a transformer main body 105, a coil portion 106 without a protective cover, an insulating plate 107, leads 108, and the like. The leads 108 of the transformers 101a and 101b are fixed to the electrodes on the back surface of the printed circuit board 103 by solder 110 through through holes provided in the printed circuit board 103. After mounting other electronic components on the printed circuit board 103, the mold resin 104, which is an insulating resin made of polyurethane or the like, is heated and introduced onto the printed circuit board 103, and then cooled and fixed. Polyurethane has a low viscosity in a heated state, and as shown in FIG. 3B, the polyurethane is also filled in the lower part of the coil part 106 where a protective cover is not formed, and solidifies after cooling.
Japanese Utility Model Publication No. 6-44117 Japanese Patent Laid-Open No. 11-195538

  The surface of the coil portion 106 made of winding is usually covered with tape or the like. When the mold resin 104 flows in and contacts the insulating tape of the coil portion 106, the insulating tape is heated and cooled and peels off from the surface of the coil portion 106, or the mold resin 104 enters from the gap of the insulating tape. The mold resin 104 was in direct contact with the coil portion 106. Therefore, the coil unit 106 is heated and cooled, and further, stress is applied to the winding of the coil unit 106 due to the shrinkage at the time of cooling of the mold resin 104, and problems such as cutting of the winding and poor connection occur. There was a problem.

  In order to solve the above-described problem, there is a problem in that it is expensive to seal the coil unit 106 with a protective cover.

  The present invention has taken the following means in order to solve the above problems.

(1) In the printed circuit board mounted product of the present invention, a printed circuit board mounted product in which a transformer including a coil portion and an electrode lead is mounted on the printed circuit board, and the surface of the printed circuit board is covered with a mold resin layer. The transformer is housed in a box-shaped storage case having an opening at the top, and the lead of the transformer penetrates through a through hole provided in the bottom of the storage case, and the penetrated lead is fixed to the printed circuit board. The storage case and the transformer are mounted on the printed circuit board, and the box-shaped storage case includes a side plate that surrounds the transformer and a bottom plate on which the transformer is placed, and a bottom portion of the side plate is attached to the printed circuit board. It abuts the bottom plate is spaced through a clearance from the printed circuit board, the mold resin layer, on top of the opening of the storage case Have a thickness which is not, it is characterized in that no contact with the coil portion of the being shielded transformer by the storage case.

(2) In the printed circuit board mounted product according to (1) , the transformer includes a core wound by the coil portion and two insulators fixed to the core and sandwiching the coil portion. The lead is installed at the end of the bag, the end of the bag is in contact with the bottom of the storage case, and the coil is separated from the bottom of the storage case via a gap. It is characterized by.

  When a printed circuit board is molded with a mold resin after mounting an electronic component, the transformer is prevented from entering the storage case by storing the periphery of the transformer in the storage case. I tried not to touch it. Thereby, thermal expansion and contraction of the coil due to the mold resin are prevented, and it is possible to prevent occurrence of disconnection of the coil, poor connection between the coil and the terminal, and the like due to the expansion and contraction.

  Moreover, since the upper part of the storage case is opened, the transformer body is not molded by the mold resin, and it is possible to easily confirm the transformer part number, specifications, etc. described on the upper part of the transformer body. Have advantages.

  In the printed circuit board mounting product according to the present embodiment, a transformer having a coil part and leads for extracting electrodes from the coil part is mounted on the printed circuit board, and the printed circuit board is further covered with a mold resin. The transformer is stored in a box-shaped storage case having an upper opening. A through hole is formed in the bottom of the storage case, and the lead of the transformer passes through the through hole and is fixed to the printed board and mounted. Further, the mold resin is formed with a thickness that does not reach the upper part of the opening of the storage case, and is shielded by the storage case so that the mold resin and the coil portion do not come into contact with each other. As a result, since the mold resin and the coil portion do not come into contact with each other, thermal expansion and contraction of the coil portion due to the mold resin can be prevented, and disconnection and poor connection of the coil portion can be prevented.

  Further, the box-shaped storage case includes a side plate surrounding the transformer and a bottom plate on which the transformer is placed. The bottom of the side plate of the storage case is installed so as to contact the printed circuit board, and a gap is formed between the bottom plate of the storage case and the printed circuit board so that the bottom plate of the storage case and the printed circuit board do not contact each other. . As a result, even if the mold resin enters between the bottom plate of the storage case and the printed board, it can be prevented from creeping into the storage case through the lead of the transformer and the through hole provided in the bottom plate of the storage case. It is possible to more reliably prevent contact between the coil portion and the mold resin.

  Further, the transformer includes a core wound by the conductive wire of the coil portion, and a flange made of two insulators that are fixed to the core and sandwich the coil portion. The lead for electrode extraction is planted at the end of the ridge. Further, the end of the ridge in which the lead is implanted is in contact with the bottom of the storage case and supports the transformer. Further, the lower part of the coil part and the bottom part of the storage case are separated from each other through a gap and are configured not to contact each other. That is, even if the mold resin crawls up into the storage case, the mold resin and the coil portion are not in contact with each other.

  Hereinafter, the printed circuit board mounted product of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram for explaining a state in which one transformer 1 is stored in a storage case 2 and mounted on a printed circuit board 3. The transformer 1 includes a transformer main body that encloses the coil portion 5 and the core 4, a flange 6 that is an insulating plate that sandwiches the coil portion 5 from both sides, and a lead 8 that is provided on a lower side that is an end of the flange 6. A protrusion 7 is formed at the bottom corner of the collar 6.

  A storage case 2 for storing the transformer 1 has a box-like shape with an open top. The bottom plate 10 of the storage case 2 is installed in a raised shape with respect to the bottom side of the side plate 9. The bottom plate 10 is formed with a lead hole 11 for penetrating the lead 8 of the transformer 1 and the protrusion 7 of the flange 6 and a positioning hole 12 for positioning the transformer 1. Since the bottom plate 10 of the storage case 2 is raised to the side plate 9 and installed in a bottom shape, when the storage case 2 is mounted on the printed circuit board 3, a gap is generated between the surface of the printed circuit board main body 13 and the lower surface of the bottom plate 10 and does not come into contact. . Therefore, even when the mold resin oozes out from the bottom side of the side plate 9 of the storage case 2 to the lower part of the bottom plate 10, the oozing into the inside can be further suppressed. The storage case 2 uses an insulating resin.

  The printed circuit board 3 has a region 14 for mounting the transformer 1 on the printed circuit board main body 13, and the region 14 has a lead 8 penetrating the transformer 1 and is fixed to the electrode formed on the back surface by soldering. Through-holes 15 are formed.

  The transformer 1 housed in the storage case 2 is installed in the area 14 of the printed circuit board 3, and the lead 8 of the transformer 1 is passed through the lead hole 11 of the storage case 2 and the through hole 15 of the printed circuit board 3 to reverse the back surface of the printed circuit board 3. Fix by soldering. Further, the projection 7 of the flange 6 of the transformer 1 is inserted into the positioning hole 12 of the storage case 2, so that the transformer 1 is positioned with respect to the storage case 2. In this way, it is possible to easily mount the transformer without increasing the number of steps as compared with mounting the conventional transformer on the printed circuit board 3 without the storage case 2. The storage case 2 and the transformer 1 are mounted on the printed circuit board 3 in addition to the method of fixing the leads 8 with solder as in the above embodiment, and the transformer 1 and the storage case 2 are fixed to the printed circuit board 3 with screws. You may fix by the method of doing.

  FIG. 2 shows a printed circuit board mounting product in which two transformers 1a and 1b are housed in parallel in a housing case 2 and fixed to the printed circuit board 3 to form a mold resin 20. 2A is a top view, FIG. 2B is a cross-sectional view of the portion X-X ′, and FIG. 3C is a cross-sectional view of the portion Y-Y ′. The same parts or functions as those in FIG. 1 are denoted by the same reference numerals.

  2A shows a state where two transformers 1a and 1b are housed inside the side plate 9 of the housing case 2. FIG. A gap G is provided between the outer peripheral portions of the cores 4 a and 4 b of the two transformers 1 a and 1 b and the inner wall of the side plate 9 of the storage case 2. When the printed circuit board 3 is driven, the transformers 1a and 1b generate heat. By providing the gap G, the heat generated by the transformers 1a and 1b can be efficiently radiated. Moreover, since the upper part of the storage case 2 is open, it is possible to confirm the product number and specifications described on the upper part of each transformer body.

  2B, the leads 8 of the transformer 1a and the transformer 1b penetrate through the bottom plate 10 of the storage case 2 and the lead holes 11 and the through holes 15 provided in the printed circuit board main body 13. The printed circuit board body 13 and the transformers 1a and 1b are fixed by soldering the leads 8 of the transformer 1a and the transformer 1b to the back surface of the printed circuit board body 13 with solder 21. The bottom plate 10 of the storage case 2 is raised above the bottom of the side plate 9. This is to prevent the mold resin 20 oozing out from the bottom of the side plate 9 from creeping up through the positioning hole 12 and the lead hole 11. For the same reason, the tip of the positioning projection 7 provided at the end of the flange 6 passes through the bottom plate 10 but is fixed so as to be separated from the surface of the printed board main body 13.

  In FIG. 2C, a lead 8 is attached to the bottom of the flange 6 of the transformer 1b. The coil unit 5 is separated by a separation plate 23. A space is provided between the lower part of the coil part 5 and the bottom plate 10 of the storage case 2, and even when the mold resin 20 oozes out through the lead hole 11 and the positioning hole 12, the mold resin 20 and the coil The portion 5 is prevented from contacting.

  As described above, since the transformer 1 is stored in the storage case 2 so that the mold resin 20 and the transformer main body are not in contact with each other, the transformer main body is affected by the thermal characteristics, expansion and contraction characteristics of the mold resin 20. It can be implemented without.

Explanatory drawing for demonstrating the mounting method of the printed circuit board mounting goods which concern on this Embodiment. It is the upper side figure and side sectional view showing the printed circuit board mounting goods concerning this embodiment. It is a sectional side view showing the state which mounted the transformer on the conventionally well-known printed circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transformer 2 Storage case 3 Printed circuit board 4, 4a, 4b Core 5 Coil part 6 鍔 7 Protrusion part 8 Lead 9 Side board 10 Bottom board 11 Lead hole 12 Positioning hole 13 Printed circuit board main body 15 Through hole 20 Mold resin

Claims (2)

A transformer provided with a coil portion and leads for electrode drawing is mounted on a printed circuit board, and the printed circuit board mounted product has a surface of the printed circuit board covered with a mold resin layer,
The transformer is housed in a box-shaped storage case having an open top, and the lead of the transformer penetrates through a through-hole provided in the bottom of the storage case, and the penetrated lead is fixed to the printed circuit board. And the transformer are mounted on the printed circuit board,
The box-shaped storage case includes a side plate surrounding the transformer and a bottom plate on which the transformer is placed, the bottom of the side plate abuts on the printed circuit board, and the bottom plate is separated from the printed circuit board through a gap,
The printed circuit board mounted product, wherein the mold resin layer has a thickness that does not reach an upper portion of the storage case that is open, is shielded by the storage case, and is not in contact with a coil portion of the transformer.   The transformer includes a core wound by the coil part, and a gutter composed of two insulators fixed to the core and sandwiching the coil part, and the lead is installed at an end of the gutter. 2. The printed circuit board mounted product according to claim 1, wherein an end portion of the flange is in contact with a bottom portion of the storage case, and the coil portion is separated from the bottom portion of the storage case via a gap. .

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