JP2709973B2 - Heat dissipation mechanism of transistor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a heat dissipation mechanism of a transistor used in an electronic device.

[Prior art]

Conventionally, a mechanism shown in FIG. 7 has been known as a transistor heat dissipation mechanism. A printed board 71 is cross-linked vertically to the side wall 72 of the metal case. The transistor 70 is on the printed board 71,
It stands upright on the printed circuit board 71. Transistor
A cap-shaped heat dissipation cap 74 made of a good heat transfer material is covered from the head of the columnar case 73 of 70, and the heat dissipation cap 74 is fixed in contact with a heat dissipation plate 75 of the good heat transfer material at its upper part. I have. And the heat radiation plate 75 is the side wall of the metal case
Fixed to 72.

[Problems to be solved by the invention]

The conventional heat dissipating mechanism, as described above,
A heat-dissipating plate 75 that is separated by about the height of the transistor 70 exists on the upper side of the transistor 70. For this reason, there is a problem that the stray capacitance with respect to the electronic circuit provided on the printed circuit board 71 increases, which adversely affects the electronic circuit. Therefore, if the distance between the heat radiating plate 75 and the printed board 71 is increased, the heat radiating cap 74 must be formed in a shape having a thickness in the height direction of the transistor 70. Therefore, when the heat radiation plate 75 is fixed to the side wall 72 of the metal case,
Even if the fixing position is slightly shifted, the heat dissipation cap 74 is inclined, and stress is applied to the lead portion of the transistor, which causes a component failure and makes the mounting difficult. vice versa,
In order to prevent stress and facilitate mounting, it is necessary to provide a clearance between the columnar case 73 of the transistor 70 and the heat dissipation cap 74. Due to this clearance, heat conduction between the columnar case 73 and the heat dissipation cap 74 is deteriorated, and there is a problem that heat dissipation efficiency is not good. Further, the heat radiation source of the transistor 70 is near the substrate 76 on which the transistor chip is mounted. Therefore, in order to improve the heat dissipation effect, it is necessary to cover the heat dissipation cap 74 deeply near the substrate 76. However, in such a case, the electronic circuit disposed on the printed board 71 and the heat dissipation cap 74
And the stray capacitance increases. The present invention has been made to solve the above problems, and an object of the present invention is to improve the heat dissipation efficiency of a transistor without deteriorating electrical characteristics.

[Means for Solving the Problems]

The configuration of the invention of claim 1 for solving the above-mentioned problem is as follows.
The transistor is perpendicular to the wall, i.e., on the surface of the printed circuit board, so that the bottom of the columnar case of the transistor is substantially flush with the inner surface of the wall in the hole formed in the wall of the metal case supporting the printed circuit board. It is a columnar body with a term of diameter slightly smaller than the diameter of the columnar case at the center, penetrating parallel to the outside of the metal case, and connecting the hole and the outside of the side surface at the meat around the hole. Then, by forcibly penetrating the heat dissipating ring formed of a good heat conductor having a slit extending in the axial direction of the hole to the root of the columnar case of the transistor, the gap between the slits is enlarged. It is characterized in that the columnar case is brought into close contact with the side wall of the columnar case at the root portion of the columnar case by the elastic force generated in the opposed meat portion. According to a second aspect of the present invention, in addition to the first aspect, the end surface of the heating ring is closely fixed to the wall surface of the metal case so as to maintain high heat conduction. According to a third aspect of the present invention, in addition to the first aspect, a top portion formed of a good heat transfer member and in contact with the upper surface of the heat radiating ring, and a base formed on both sides of the top portion and in contact with the outer surface of the wall surface of the metal case. The heat radiating ring is fixed by suppressing the heat radiating ring from the upper surface of the heat radiating ring toward the wall surface of the metal case by using a suppressing plate having a portion continuously formed in a square wave shape. Further, according to the invention of claim 4, a heat dissipation plate formed of a good heat transfer body having holes formed at positions corresponding to the holes formed on the wall surface of the metal case is joined to the outside of the wall surface of the metal case. That is, a heat radiating ring penetrating through the transistor is provided so as to be tightly fixed to the heat radiating plate.

[Action]

According to the first and second aspects of the present invention, the heat generated in the transistor chip is transmitted to the columnar case of the transistor and the heat radiating ring in this order and is radiated to the air, and a part of the heat is transmitted from the heat radiating ring to the metal case. The heat transmitted to the metal case is finally radiated into the air. According to the third aspect of the invention, the heat generated in the transistor chip is transmitted to the columnar case of the transistor and the heat radiating ring in this order and is radiated to the air, and further transmitted to the suppressing plate and the metal case and finally radiated to the air. . According to the fourth aspect of the invention, heat generated in the transistor chip is transmitted to the columnar case of the transistor and the heat radiating ring in this order, is radiated into the air, and is transmitted to the heat radiating plate. The heat transmitted to the heat radiating plate is radiated into the air, and part of the heat is transmitted to the metal case and finally radiated into the air.

【The invention's effect】

Since all of the above-described heat radiation mechanisms are provided outside the metal case, electrical interference such as an increase in stray capacitance and an increase in leakage inductance with an electronic circuit on a printed circuit board is prevented. Also, since electrical interference is prevented, the size of the heat radiating ring, suppression plate, heat radiating plate, and the like can be increased, so that the heat radiating effect is improved. Further, since the transistor is disposed parallel to the surface of the printed circuit board and facing the end surface, even if the transistor is disposed outside the metal case, the wiring to the printed circuit board may be short, and the high-frequency characteristics deteriorate. Never. According to the first, second and third aspects of the present invention, a heat radiation ring having a hole having a diameter slightly smaller than the diameter of the case at the center and a slit extending in the axial direction in a wall around the hole is provided in the columnar case. The columnar case is forcibly penetrated to the root portion, and the elasticity generated in the flesh portion against the expansion of the gap between the slits makes the columnar case adhere to the side wall of the columnar case at the root portion. Therefore, as a result of the outer peripheral surface of the columnar case and the inner peripheral surface of the hole of the heat radiation ring being firmly adhered to each other, the heat radiation effect of the transistor becomes extremely high. Further, the mounting of the heat radiating ring to the columnar case for the purpose of firmly adhering to the radiating ring can be performed very easily. According to the third aspect of the present invention, the top portion contacting the upper surface of the heat radiating ring and the base formed on both sides of the top portion and contacting the outer surface of the wall surface of the metal case are continuously formed in a square wave shape. The heat radiating ring is fixed by holding the heat radiating ring from the upper surface of the heat radiating ring toward the wall surface of the metal case. Therefore, while fixing the transistor becomes easy,
As a result, the heat dissipation path is formed to the heat dissipation ring, the suppression plate, and the metal case, so that the heat dissipation effect is enhanced.

【Example】

Hereinafter, the present invention will be described based on a specific example. An embodiment according to the second invention will be described. In FIG. 2, a box-shaped metal case 10 of an electronic device has a side wall 11 and a bottom plate 12, and a printed circuit board 13 on which an electronic circuit is provided is provided inside. As shown in FIG. 1, the printed circuit board 13 is a metal case 10
At a middle portion in the height direction of the side wall 11, the side wall 11 is provided so as to be bridged in a direction perpendicular to the side wall 11. Side wall 11
In the portion of the printed circuit board 13 facing the end face 131, a hole 14 is provided.
The transistor 20 having the columnar case 21 in the hole 14 is penetrated toward the outside of the side wall 11. A heat radiating ring 30 having the shape shown in FIG. 3 penetrates through the columnar case 21 of the transistor 20. The hole of the heat dissipation ring 30
31 is slightly smaller than the outer diameter of the columnar case 21, and a slit 32 is formed in the flesh portion for cutting in the length direction. When the heat radiating ring 30 is forcibly penetrated through the columnar case 21, the hole 31 of the heat radiating ring 30 is enlarged by the slit 32. As a result, the heat dissipation ring 30 is firmly and closely contacted with the columnar case 21 of the transistor 20 by the elastic force of the heat dissipation ring 30. The side wall of the columnar case 21 and the inner wall of the heat radiating ring 30 are in close contact with each other, and the end face of the heat radiating ring 30 and the substrate 22 are in close contact with each other. As a result, heat generated in the transistor chip 27 is efficiently transmitted to the heat radiation ring 30. As shown in FIG. 4, the suppression plate 40 has a cross section perpendicular to the long axis manufactured in a square wave shape, and is composed of base portions 41 and 42 and a top portion 43. A hole 44 is formed in the top 43, and the head 23 of the columnar case 21 of the transistor 20 projects through the hole 44. The pressing plate 40 is screwed down and fixed by the screw 45 so that the base portions 41 and 42 come into contact with the side wall 11 of the metal case 10. Board 40
With the screw tightened and fixed, the heat dissipation ring 30 is strongly pressed against the metal case 10 by its own elastic force,
The upper surface 33 of the plate 30 and the top 43 of the suppressing plate 40, the bottom surface 34 of the heat radiating ring 30, and the side wall 11 of the metal case 10 are in strong close contact. As a result, the heat generated by the transistor 10 is generated by the columnar case 21, the heat radiating ring 30, the top 43 of the suppressor 40, its base 41,
The heat is radiated through a path of the side wall 11 of the metal case 10 and the bottom plate 12 of the metal case 10. Heat dissipation ring 30, metal case 10
The heat is also radiated in parallel through the path of the side wall 11. As described above, since the transistor 20 protrudes outside the metal case 10 and the heat dissipation mechanism such as the heat dissipation ring 30 and the suppression plate 40 is formed outside the metal case 10, the transistor 20 is disposed on the printed circuit board 13 by the heat dissipation mechanism. Electrical interference to electronic circuits is eliminated. The electrical connection between the transistor 20 and the printed circuit board 13 is connected at the end of the printed circuit board 13 by the leads 24, 25, and 26. The columnar case 21 is a metal case
Soldered to 10. The emitter lead 26 passes through the feedthrough capacitor 28, and the ground electrode of the feedthrough capacitor 28 is electrically connected to the substrate 22. As described above, since the leads 24, 25, and 26 of the transistor 20 are connected near the printed circuit board 13, the high-frequency characteristics do not deteriorate even though the transistor is provided outside the metal case 10. In the above embodiment, the hole 44 may not be provided, and the top portion 43 may be raised to cover the top portion 23 of the columnar case 21 from above. When the holes 44 are provided, there are the following advantages. It is easy to visually confirm the mounting state of the transistor 20. Hole
44 makes it easy to position the transistor 20 in the assembling position. By projecting the head 23 of the transistor 20 from the hole 44, the size of the device can be reduced. The pressing plate 40 is, as shown in FIG.
May be formed only at the portion where the bottom plate 12 is disposed so as not to contact the bottom plate 12. FIG. 6 is a diagram showing an embodiment according to the third invention. The configuration of the metal case 10 and the side wall 11 thereof is the same as in the above embodiment. In the present embodiment, a heat dissipation plate 50 formed of a flat good heat conductor is disposed on the side wall 11. The heat radiation plate 50 has a hole 51 through which the transistor 20 passes. The transistor 20 has the side wall 11 similar to the above embodiment.
And the hole 51 of the heat dissipation plate 50 penetrates outward. A heat dissipation ring 30a having the same configuration as that of the above embodiment is penetrated through the columnar case 21 of the transistor 20 in a state of being in close contact therewith. The heat radiating ring 30a is screwed and fixed to the heat radiating plate 50 by a screw 52. In the heat dissipation mechanism having such a configuration, the heat generated by the transistor 20 is dissipated through a path including the columnar case 21, the heat dissipation ring 30a, and the heat dissipation plate 50. Further, the heat dissipation plate 50 is formed in an L-shape at the lower portion so as to be joined to the bottom plate 12, but may be a flat shape that contacts only the side wall 11. The embodiment of the first invention can be realized by directly screwing and fixing the heat radiation ring 30 to the side wall 11 of the metal case 10 without interposing the heat radiation plate 50 in the above third invention.

[Brief description of the drawings]

FIG. 1 is a mechanism diagram showing a heat dissipation mechanism of a transistor according to a specific embodiment of the present invention, FIG. 2 is a perspective view showing the entire heat dissipation mechanism, and FIG. 3 is a perspective view showing a heat dissipation ring. FIG. 4 is a perspective view showing a suppressor, FIG. 5 is a mechanism diagram showing a heat radiating mechanism according to a modification of the first embodiment, and FIG. 6 is a mechanism diagram showing a heat radiating mechanism according to another embodiment. FIG. 7 is a mechanism diagram showing a conventional heat dissipation mechanism of a transistor. 10: Metal case, 11: Side wall 12: Bottom plate, 13: Printed circuit board, 14: Hole 20: Transistor, 21: Columnar case 22: Substrate, 30: Heat dissipating ring, 40: Suppression plate

Claims (4)

(57) [Claims] 1. A heat dissipation mechanism for a transistor having a columnar case used in an electronic device having a box-shaped metal case and a printed circuit board provided between the wall surfaces of the metal case. A hole is formed in a wall surface of the metal case having an end surface facing the outside, and the transistor is disposed outside the metal case in a direction perpendicular to the wall surface so that a bottom surface of the columnar case is substantially flush with an inner surface of the wall surface. A column having a hole having a diameter slightly smaller than the diameter of the columnar case in the center thereof, and a wall around the hole, the hole and the side surface being provided. By communicating with the outside, a heat radiation ring formed of a good heat conductor having a slit extending in the axial direction of the hole is forcibly penetrated to the root of the columnar case of the transistor, By the elastic force generated in the meat portion resisting the gap between slits is enlarged, the heat radiation mechanism of the transistor, characterized in that in close contact with the side wall of the columnar case the base portion of the columnar case. 2. The transistor heat dissipation mechanism according to claim 1, wherein an end face of said heat dissipation ring is closely fixed to a wall surface of said metal case so as to maintain high heat conduction. 3. The metal case according to claim 1, further comprising: a top portion formed of a good heat transfer member and in contact with an upper surface of the heat radiating ring; and a base portion formed on both sides of the top portion and in contact with an outer surface of a wall surface of the metal case. A heat dissipating mechanism for a transistor, wherein a heat dissipating ring is fixed by suppressing the heat dissipating ring from a top surface of the heat dissipating ring toward a wall surface of the metal case by a suppressor formed continuously in a square wave shape. 4. A heat dissipation mechanism for a transistor having a columnar case used in an electronic device having a box-shaped metal case and a printed circuit board disposed between the wall surfaces of the metal case, A hole is formed in the wall surface of the metal case whose end face is opposed, and a heat dissipation plate formed of a good heat transfer body having a hole formed at a position corresponding to the hole is joined to the outside of the wall surface of the metal case. A transistor is directed to the outside of the case in a direction perpendicular to the wall surface, the holes of the metal case and the holes of the heat radiating plate are penetrated, and a ring-shaped heat radiating ring formed of a good heat conductor is formed on the transistor. That the bottom surface of the heat dissipation ring is fixedly contacted with the heat dissipation plate, and that the bottom surface of the case is in close contact with the side wall of the case. Heat radiation mechanism of the transistor, characterized.