JP2008187142A - Mounting structure of diode on printed circuit board - Google Patents

Abstract

Disclosed is a diode mounting structure on a printed wiring board that is excellent in heat dissipation and advantageous in terms of cost.
In a mounting structure in which lead wires 1a, 1a of a diode 1 are inserted into through holes 2a, 2a of a printed wiring board 2 and fixed to a wiring pattern with solder 3a, 3a, a recess 4a into which the diode 1 is fitted is provided. The radiating plate 4 is erected on the diode mounting portion of the printed wiring board 2, the diode 1 is fitted into the recess 4a, and the lead wires 1a and 1a are fixedly adhered to the radiating plate 4 with solder 3b and 3b. A diode mounting structure is adopted. Heat generated in the diode 1 is immediately conducted to the heat radiating plate 4 through a heat conduction path formed by the lead wire 1a and the solder 3b, and is efficiently radiated from the surface of the heat radiating plate 4. Therefore, since an inexpensive so-called straight product having poor heat dissipation can be used as the diode, it is advantageous in terms of cost.
[Selection] Figure 2

Description

  The present invention relates to a mounting structure of a diode on a printed wiring board, and more particularly to an improved mounting structure that improves heat dissipation and prevents adverse effects due to temperature rise.

  When mounting a diode with a large amount of heat generation on a printed wiring board, if the heat dissipation is insufficient, the temperature of the diode and its peripheral components may rise, which may be adversely affected by heat. Therefore, when the amount of heat generated by the diode is large, a so-called forming product with good heat dissipation in which the diode is mounted in a floating state is used to suppress the temperature rise and prevent adverse effects due to heat.

  On the other hand, as a technique for improving heat dissipation, for example, a silicon substrate with a fine wiring layer formed thereon is used as a circuit board, and a VLSI chip is attached to the front surface side with an alloy layer and heat conduction is performed on the back surface side of the circuit board. A mounting method is known in which a heat dissipating fin is attached with thermal grease having a high rate (Patent Document 1).

In addition, a semiconductor device (Patent Document 2) in which a semiconductor chip is arranged on an island portion of a lead frame and a radiating fin is attached to a package on the upper side of the island portion, or a heat sink having a base with good thermal conductivity for mounting a semiconductor chip There is also known an electronic device (Patent Document 3) in which heat dissipation is improved by using a device.
Japanese Patent Laid-Open No. 5-21257 JP 9-213871 A JP-A-60-98650

  However, the conventional so-called forming product has good heat dissipation but is economically disadvantageous because of its high price. Further, the mounting method disclosed in Patent Document 1 conducts heat from the VLSI chip through the alloy layer, silicon substrate, and thermal grease to the heat dissipating fin on the back surface, and dissipates heat from the surface of the fin. However, it is difficult to expect a sufficient heat dissipation effect even if a diode is mounted by diverting such a mounting method. Further, the heat dissipating structures of Patent Documents 2 and 3 are difficult to adopt for mounting diodes, and the heat dissipating efficiency is not good.

  The present invention has been made under the above circumstances, and a problem to be solved is to provide a mounting structure of a diode on a printed wiring board which is excellent in heat dissipation and advantageous in terms of cost.

  In order to solve the above problems, a mounting structure of a diode on a printed wiring board according to the present invention is a mounting structure in which a lead wire of a diode is inserted into a through hole of a printed wiring board and soldered to a wiring pattern. A heat sink having a recessed portion to be fitted is erected at a diode mounting position of the printed wiring board, the diode is fitted into the recess, and the lead wire of the diode is closely attached to the heat sink. Is.

  In the mounting structure of the present invention, it is preferable to use, as the heat radiating plate, a split board that is formed at an end of the printed wiring board and has a recess into which a diode is fitted, separated from the printed wiring board.

  A more specific preferable mounting structure of the present invention is a mounting structure in which a lead wire of a diode is inserted into a through hole of a printed wiring board and soldered to a wiring pattern, and is formed at an end portion of the printed wiring board and A split board having a recess into which the diode is fitted is separated from the printed wiring board and used as a heat sink, and the split board is erected at a diode mounting position of the printed wiring board, and the diode is placed in the concave part. And the lead wire of the diode is soldered to the exposed copper foil surface of the split substrate.

  According to the mounting structure of the diode on the printed wiring board according to the present invention, the heat generated in the diode is conducted to the heat sink through the lead wire, and is radiated from the surface of the heat sink. As described above, in the mounting structure of the present invention, the heat conduction path from the diode to the heat sink is a lead wire having good heat conductivity. Therefore, the heat generated in the diode is immediately conducted to the heat sink, and the heat sink It is possible to efficiently dissipate heat from the surface to suppress the temperature rise of the diode and peripheral components, and to prevent adverse effects of heat on the diode and peripheral components. Therefore, even in the case of a diode that generates a large amount of heat, instead of the conventional expensive so-called forming product, it is possible to use an inexpensive so-called straight product that is mounted on a printed wiring board in a contact state and not so good in heat dissipation. Is advantageous.

  In addition, a mounting structure that uses a split board that is formed at the end of a printed wiring board and has a recess into which a diode is fitted as a heat sink is used separately from the printed wiring board. Cost can be saved, and an unnecessary end portion of the printed wiring board can be effectively used, which is further advantageous in terms of cost.

  Then, as a more specific preferable mounting structure, the split board separated from the printed wiring board is set up as a heat sink on the diode mounting portion of the printed wiring board, and the diode is fitted into the recess of the split board, In the case where the lead wire is soldered to the exposed surface of the copper foil of the split substrate, the solder and the lead wire form a heat conduction path having a large cross-sectional area and excellent thermal conductivity, and the lead wire and the split substrate are in close contact with each other. Therefore, the heat conduction from the diode to the split substrate is further improved, and the heat dissipation is further improved. In addition, since the split substrate is fixed to the lead wire of the diode by soldering, it is not necessary to fix the split substrate to the printed wiring board with an adhesive or the like.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  1 is a perspective view showing a mounting structure of a diode on a printed wiring board according to an embodiment of the present invention, FIG. 2 is a front view of the mounting structure, FIG. 3 is a right side view of the mounting structure, and FIG. FIG. 5 is a partial plan view of a printed wiring board used for the mounting structure before soldering the mounting structure.

  As shown in FIG. 4, the mounting structure of this embodiment is a diode covered with a covering material in a cylindrical shape, and the tip portions of the lead wires 1a and 1a protruding from both ends of the diode 1 are bent downward at a right angle. The case where the so-called straight product is used and mounted on the surface of the printed wiring board 2 is illustrated, and two through holes 2a and 2a are formed in the diode mounting portion of the printed wiring board 2 with the lead wires. 1a and 1a are perforated at the same interval as the interval between the tip portions bent downward.

  As shown in FIGS. 2 and 3, the through holes 2a and 2a of the printed wiring board 2 are inserted with the tip portions bent downward of both the lead wires 1a and 1a of the diode 1, and the printed wiring The lower ends of the lead wires 1a and 1a protruding from the back surface of the substrate 2 are connected and fixed to a wiring pattern (not shown) on the back surface of the printed wiring board 2 by solders 3a and 3a. It is mounted in contact.

  As shown in FIGS. 1 to 3, a heat radiating plate 4 is erected at a diode mounting portion of the printed wiring board 2. The heat sink 4 is a horizontally long heat sink whose height is higher than that of the diode 1 and whose length is longer than the mutual distance between the tip portions bent downward of the lead wires 1a and 1a. As shown in FIG. 4, a rectangular recess 4 a into which the diode 1 is fitted is formed at the center of the lower end of the heat radiating plate 4.

  As shown in FIG. 5, the heat sink 4 is formed in the shape of the heat sink as described above by providing a split groove 2c leaving a connecting portion 2b at an unnecessary end of a discarded substrate of the printed wiring board 2. It is composed of a split substrate 4 and is separated from the printed wiring board 2 by cutting the connecting portion 2b during mounting. Since the surface of the split substrate 4 is a copper foil exposed surface, the lead wires 1a and 1a of the diode 1 can be soldered as described later, and the heat dissipation is good. Needless to say, the split substrates 4 are formed at unnecessary ends of the printed wiring board 2 by the same number as the number of diodes 1 to be mounted. In order to further improve the heat dissipation, it is preferable to make the area of the split substrate 4 as large as possible within a possible range.

  In the mounting structure of this embodiment, the heat radiating plate 4 made of the split substrate 4 is used as described above. However, the present invention is not limited to this, and other materials such as solderable metal having good thermal conductivity are available. The heat radiating plate 4 may be separately made of the above material.

  As shown in FIGS. 1 and 3, the heat radiating plate 4 made of the above-described split substrate 4 has the lead wires 1 a and 1 a of the diode 1 on the copper foil exposed surface of the heat radiating plate 4 at the diode mounting portion of the printed wiring board 2. It is erected so as to be slightly deviated to one side of the center axis of the diode 1 so as to come into contact, and the diode 1 is fitted in the recess 4 a of the heat radiating plate 4. As shown in FIGS. 1 to 3, the lead wires 1a and 1a are firmly fixed to the exposed surface of the copper foil with the solder 3b and 3b over the entire length of the contact portion of the heat sink 4 with the exposed surface of the copper foil. Has been.

  1 to 4 each show that one diode 1 is mounted on the printed wiring board 2, but the mounting structure of the present invention has one or more diodes 1 and other diodes 1. Various electronic components (not shown) are also mounted on the printed wiring board 2.

  In the above mounting structure, the lead wires 1a and 1a of the diode 1 are firmly fixed to the exposed surface of the copper foil of the heat radiating plate 4 by solders 3b and 3b, so that the lead wires 1a and 1a and the solder 3b, 3b forms a heat conduction path having a large cross-sectional area and good heat conductivity between the diode 1 and the heat radiating plate 4, so that the heat generated in the diode 1 is quickly radiated through the heat conduction path. Conducted by the plate 4 and efficiently radiated from the surface of the heat radiating plate 4. Therefore, even if an inexpensive so-called straight product that does not have good heat dissipation is mounted as the diode 1 as in the above-described mounting structure, the heat dissipation is greatly improved, and the temperature rise of the diode 1 and peripheral parts can be suppressed. The adverse effects due to heat can be sufficiently prevented, and the diode 1 is advantageous in terms of cost because an inexpensive straight product can be used.

  In addition, if the split board 4 formed on the unnecessary end of the printed wiring board 2 is used as the heat sink 4 as in the mounting structure described above, the cost of separately manufacturing the heat sink with other materials can be saved. In addition, an unnecessary end portion of the printed wiring board 2 can be effectively used, which is further advantageous in terms of cost.

  As mentioned above, the mounting structure of the diode of the present invention has been described with reference to one embodiment. However, the present invention is not limited to this embodiment. For example, a large number of small through holes are formed as a heat sink. Thus, it is possible to allow various modifications such as using a heat radiating plate that increases the heat radiating area and improves the air permeability to improve the heat radiating efficiency.

It is a perspective view which shows the mounting structure of the diode to the printed wiring board which concerns on one Embodiment of this invention. It is a front view of the mounting structure. It is a right view of the same mounting structure. It is a disassembled front view before soldering of the mounting structure. It is a fragmentary top view of the printed wiring board used for the mounting structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diode 1a Diode lead wire 2 Printed wiring board 2a Through-hole 2b Connection part 2c Split groove 3a, 3b Solder 4 Heat sink (split board)
4a recess

Claims (3)

In the mounting structure where the lead wire of the diode is inserted into the through hole of the printed wiring board and soldered to the wiring pattern,
A split board formed at an end of the printed wiring board and having a recess into which the diode is fitted is separated from the printed wiring board and used as a heat sink, and the split board is used as a diode mounting portion of the printed wiring board. A structure for mounting a diode on a printed wiring board, wherein the diode is fitted into the recess and the lead wire of the diode is soldered to the exposed copper foil surface of the split board. In the mounting structure where the lead wire of the diode is inserted into the through hole of the printed wiring board and soldered to the wiring pattern,
A heat sink having a recess into which the diode is fitted is erected at a diode mounting position of the printed wiring board so that the diode is fitted into the recess and the lead wire of the diode is in close contact with the heat sink. Characteristic mounting structure of diode on printed circuit board.   The split board, which is formed at an end portion of the printed wiring board and has a recess into which the diode is fitted, is used as the heat sink separately from the printed wiring board. Implementation structure.

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