JPH04162790A - Structure for mounting discrete parts on board - Google Patents

Abstract

PURPOSE:To improve the vibration resistance and shock resistance of heat radiative discrete parts by inserting the lead terminal of the discrete part into the through hole from the opposite side of a tapered face, and bringing the bottom of the parts into contact with an enameled board, and soldering the lead terminal to the land part. CONSTITUTION:A tapered face 6 and, in its periphery, a nearly circular land 7 are provided at the bottom of a board by conductive material such as metal, etc. And the lead terminal 10 is inserted into the through hole 5 from above, and the bottom 8a of a package 9 is brought into contact with the topside of an enameled board 1, and by solder 11, the lead terminal 10 is soldered to the land 7. Accordingly, the heat, which is generated in discrete parts by current application, is absorbed in the enameled board 1 through the solder 11 and the land 7, and the heat absorbed in the enameled board 1 is diffused into the metallic board 3 and is radiated into the air. Hereby, heat radiation becomes favorable, and the durability to the vibration or the shock of the discrete parts improves.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for mounting discrete components on a substrate. Specifically, the present invention relates to a structure in which a discrete component that generates heat, such as a power IC, is mounted on an enamel substrate.

[Background technology] In power supply boards and power supply circuits that use discrete components that generate a lot of heat, such as power ICs, there is a demand for higher mounting density and smaller size, and in order to achieve the desired characteristics, aluminum base A substrate with good heat dissipation properties, such as a substrate or a ceramic substrate, is used.

Furthermore, metal core substrates, enamel substrates, and the like have recently been developed as component mounting becomes more dense.

As shown in FIG. 11, the metal core substrate 51 has an insulating layer 54 made of a resin material on the surface of a metal plate 53 such as an aluminum plate or iron plate having a clearance hole 52 bored therein, and on the inner peripheral surface of the clearance hole 52. .2!5~0
．． A circuit pattern 55 is formed on the surface of the substrate 51 using a conductive material, and a through-hole electrode 56 is formed in the clearance hole 52.
A through hole 57 is formed by providing.

Further, as shown in FIG. 12, the enamel substrate 61 has an enamel insulating layer 64 formed with a thickness of 0.1111 m or less on the surface of a metal plate 63 such as an aluminum laminate or iron plate in which a clearance hole 62 has been bored. At the same time, the inner peripheral surface of the clearance hole 62 is covered with an insulating layer 64 to form a null hole 65.
A land portion 66 is provided around the through hole 65 using a conductive material.

When mounting a surface mount component 67 such as an IC (integrated circuit) on this enameled substrate 61, as shown in FIG.
Although FIG. 13 shows the case of an enamel substrate, the same applies to the case of a metal core substrate. ), the surface mount component 67 is placed on the surface of the board, and the lead portion 68 of the surface mount component e7 is placed on the surface of the board.
and the wiring pad 68 of the board e1 are soldered. Further, when mounting the discrete component 7o, the lead terminal 71 of the discrete component 7o is inserted into the through hole 65 of the board 61, and the lead terminal 71 and the land portion 66 are inserted.
were joined by solder 72.

Thus, the heat of the surface mount component 67 is absorbed into the metal plate 63 via the lead portion θ8, diffused through the metal plate 63, and dissipated into the air. Further, the heat of the discrete component 70 is absorbed by the metal plate 83 through the path of lead terminal 71 → solder 72 → land portion 66 → insulating layer 64 → metal plate 63, diffuses inside the metal plate 63, and is dissipated into the air. be done.

[Problems to be Solved by the Invention] In the metal core substrate as described above, a resin material is used as the insulating layer. Therefore, in order to ensure the insulation properties of the insulating layer, it is necessary to increase the thickness of the insulating layer. 0.25-0.301
11m is required. Therefore, high heat dissipation can be achieved with surface-mounted components that consume little power, but due to the thickness of the insulating layer, discrete components that generate a large amount of heat (e.g. electrolytic capacitors, power transistors, transformers, etc.) It was not possible to obtain sufficient heat dissipation.

On the other hand, the enamel insulating layer has high insulating properties, and the thickness of the insulating layer can be reduced to 0.1 mm or less.
Heat conduction or heat absorption from the discrete components to the core metal plate can be smoothed. Furthermore, since enamel has a high infrared emissivity, it has better properties than a metal core substrate having a resin insulating layer, such as excellent heat absorption and heat dissipation into the air.

However, in the conventional method of mounting discrete components, the heat generated in the discrete components is simply absorbed from the lead terminals to the enamel substrate. The heat generated by the heat source 73 inside the discrete component 70 is
As shown in FIG. 4, it is transmitted through the lead terminal 71 and is also emitted to the synthetic resin package 74. Here, since the thermal resistance r + r2 of the enamel insulating layer 64 is small, the heat of the discrete component 70 is absorbed from the lead terminal 71 to the metal plate e3 through the insulating layer e4, and the metal plate 63
is emitted into the atmosphere. On the other hand, the thermal resistance between the package 74 and the air interface Rr l+ R211R,...
... is large, the heat dissipated from the internal heat source 73 to the package 74 is difficult to be radiated into the air, and the heat emitted from the internal heat source 73 to the package 74 is
There was a problem in that the temperature of the discrete component 70 increased.

Also, on the lead terminal side, as shown in FIG. 13, the land portion e6 was provided perpendicularly to the lead terminal 71 around the through hole 65, so the lead terminal 71 and the land portion 66 were soldered. At this time, the contact area between the lead terminal 71 and the land portion 66 via the solder 72 was small, and the heat flow path was narrowed, thereby preventing heat radiation from the lead terminal 71.

In addition, since the discrete component is only fixed to the board at the tip of the lead terminal with solder, the discrete component is fixed in an unstable state and has the disadvantage of being susceptible to vibration and shock.

The present invention was made in view of the shortcomings of the conventional board-based examples, and its purpose is to improve heat dissipation from discrete components, and to ensure that the mounted discrete components are resistant to vibration and shock. The object of the present invention is to provide a structure for mounting discrete components on a board.

[Means for Solving the Problems] The structure for mounting a discrete component on a board of the present invention includes an enamel board in which the surface of a metal plate is covered with an enameled insulating layer, and at least a part of the board is expanded into a tapered shape. providing a through hole, forming a land portion on the tapered surface of the through hole, inserting a lead terminal of a discrete component into the through hole from the opposite side of the tapered surface, and bringing the bottom surface of the component into contact with the enamel substrate; It is characterized in that the lead terminal is soldered to the land portion.

[Function] In the present invention, the lead terminal of the discrete component is inserted into the through hole of the enamel board, the lead terminal is soldered to the land part, and the bottom surface of the discrete component is brought into contact with the surface of the board. The heat of the discrete component can be absorbed from the lead terminal to the enamel board, and the heat accumulated in the package of the discrete component can also be absorbed from the bottom of the discrete component to the enamel board, reducing the temperature rise of the discrete component. can be effectively prevented. Moreover,
Since the enamel insulating layer has high electrical insulation properties, there is no fear that the discrete component will cause an electrical short circuit even if the bottom surface of the discrete component is brought into contact with the enamel substrate. Furthermore, since the land portion is provided on the tapered surface of the through hole, the soldering area between the lead terminal and the land portion is increased, and the efficiency of heat absorption from the lead terminal to the enamel substrate is further improved.

Therefore, it is possible to prevent the discrete components mounted on the enamel substrate from being damaged by heat, and the reliability of the components can be improved.

In addition, the enamel (insulating layer) improves heat dissipation from the enamel substrate into the air, which reduces temperature rise and allows parts with lower heat resistance standards to be used, making it possible to use smaller parts. Can be used.

Furthermore, since the discrete components are supported by the enamel substrate through the lead terminals and the bottom surface, the lead terminals are less likely to bend or the solder may come off due to vibrations or shocks, improving the durability of the discrete components against vibrations and shocks.

"Example] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of the present invention. The enamel substrate 1 in this embodiment is made by covering the surface of a flat metal plate 3 such as a flat aluminum plate or iron plate with a clearance hole 2 bored therein and the inner peripheral surface of the clearance hole 2 with an enamel insulating layer 4. - A hole 5 is formed therein, and a tapered surface θ having a substantially forest-like shape is formed on the lower surface side of the inner peripheral surface of the null hole 5. This tapered surface 6
A substantially annular land portion 7 made of a conductive material such as metal is provided on the lower surface of the substrate around the land portion 7 .

8 is a discrete component sealed in a package 9 whose bottom surface is mostly flat, and the bottom surface 8a of the package 9 is enameled by inserting a lead terminal 10 protruding from the bottom surface of the package 9 into the through hole 5 from above. Lead terminals 10 are soldered to land portions 7 with solder 11 in surface contact with the upper surface of substrate 1 .

Therefore, the heat generated in the discrete component 8 due to energization is transferred from the lead terminal 10 to the solder 11 and the land portion 7.
The heat is absorbed into the enamel substrate 1 through the contact between the lead terminal 10 and the inner peripheral surface of the through hole 5, and the heat absorbed by the enamel substrate 1 diffuses inside the metal plate 3 and is absorbed into the air. Heat is radiated to. Also,
The heat accumulated in the package 9 is transferred to the discrete component 8
Heat is absorbed by the metal plate 3 from the bottom surface 8a of the metal plate 3 through the enamel insulating layer 4 having good heat absorption properties, and the heat is radiated from the metal plate 3 into the air. Therefore, the heat of the discrete component 8 is transferred from the lead terminal 10 side and the package θ side to the enamel substrate 1.
Since the heat is absorbed and radiated effectively, the temperature rise is reduced. Note that since the enameled insulating layer 4 has high insulating properties, there is no problem even if the discrete component 8 is brought into surface contact with the enameled substrate l.

Furthermore, the land 1 to which the lead terminal 10 is soldered! Since A7 is provided on the tapered surface θ, it is possible to provide the land portion 7 with a wide area, and the soldering allows smooth heat transfer from the lead terminal 10 to the land portion 7 or the enamel substrate 1 by increasing the area. can,
The heat dissipation of the Deinucrete component 8 becomes brighter. Moreover, since the bottom surface of the package 9 is brought into surface contact with the surface of the enamel substrate 1, and the lead terminals 10 are fixed with solder 11, the discrete component 8 does not move due to vibrations or shocks and is strong against vibrations and shocks. It has a structure.

What is shown in FIG. 2 is a second embodiment of the invention. In this embodiment, the bottom surface 8 of the discrete component 8 of the metal plate 3
Emboss 12 that is in contact with a and that has no through hole 5 and is protruded toward the discrete component 8 side.
This is provided. The bottom surface 8a of the discrete component 8 is brought into contact with the embossing 12, thereby lifting the bottom surface 8a of the discrete component 8 from the through hole 5. When the bottom surface 8a of the discrete component 8 is in contact with the through-hole 5, the molten solder that has risen inside the through-hole 5 during soldering spreads between the bottom surface of the discrete component 8 and the top surface of the enamel substrate 1 due to capillary action, causing electrical There is a risk of a short circuit. Therefore, if the bottom surface 8a of the discrete component 8 is made to float above the null hole 5 as in this embodiment, there is no such fear and short circuits due to the spread of the solder 11 can be prevented.

Further, FIG. 3 shows a third embodiment of the present invention.

In this embodiment, in addition to the configuration of the embodiment shown in FIG. 13 (solder, etc.). With such a configuration, heat transfer from the bottom surface 8a of the discrete component 8 to the enamel substrate 1 can be made more reliable.

FIG. 4 shows a fourth embodiment of the present invention. This is done by performing a drawing process on the through hole 5 portion of the enamel substrate 1 to form a tapered surface 6 on the lower surface side of the through hole 5, and to form a land portion 7 on this tapered surface 6. . According to this embodiment, the contact area between the lead terminal 10 and the land portion 7 via the solder 11 can be increased, and the heat dissipation efficiency from the lead terminal 10 side can be further improved.

FIG. 5 shows a fifth embodiment of the present invention. In this embodiment, a tapered surface 6 is formed in the through hole 5 on the lower surface side of the enamel substrate 1, and a relatively small-diameter land portion 7 is formed on the tapered surface θ and 6 so as not to reach the lower surface of the enamel substrate 1. It is provided on the inner peripheral surface of the through hole 5. moreover,
The length of the lead terminal 10 is made shorter than the thickness of the enamel substrate 1 so that the lower end of the lead terminal 10 does not reach the lower surface of the enamel substrate 1, and furthermore, a solder is used to solder the lead terminal 10 to the land portion 7. 11 is also enamel substrate 1
Make sure that it does not press against the bottom side.

According to such a structure, even if the enameled substrate 1 is placed on the conductor surface, the lead terminals 10 are not electrically connected to the conductor surface, thereby preventing the lead terminals 10 of the discrete components 8 from being short-circuited through the conductor surface. can.

FIG. 6 shows a sixth embodiment of the present invention. In this embodiment, the through hole 5 has a structure similar to that of the fifth embodiment.
The entire surface is formed into a tapered shape to form a tapered surface 6.

In this manner, the entire tapered surface 8 of the through hole S may be used in structures other than the fifth embodiment.

Further, FIG. 7 shows a seventh embodiment of the present invention.

In this embodiment, a relatively small tapered portion 14 is also provided on the side opposite to the tapered surface 6 of the through hole 5. According to this embodiment, since the tapered portion 14 is provided on the upper surface side of the through hole 5, when soldering the lead terminal 10, the molten solder sometimes does not reach the upper surface of the board. Therefore, similarly to the second embodiment, it is possible to prevent the solder 11 from entering between the discrete component 8 and the upper surface of the enamel substrate 1.

FIG. 8 shows a fourth embodiment of the present invention. This is an example of screen mounting, and when manufacturing the enamel board 1, the metal plate 3 is plastically deformed by press working, etc., so that the part mounting area of the metal plate 3 has a height approximately equal to the height of the discrete component. A recess 15 for component mounting is provided. Furthermore, component mounting recesses 15 are provided on both sides of the enameled substrate 1 to match the component mounting side, and each discrete component 8 is mounted on the enameled substrate 1 so as to be housed in the component mounting recess 15. .

According to such a structure, since the discrete components 8 on both sides of the enamel board 1 can be housed in almost the same plane, the thickness of the double-sided mounting board including the component height can be reduced, and a thin double-sided mounting board can be installed. Implementation becomes possible.

FIG. 9 shows a ninth embodiment of the present invention. In this embodiment, when manufacturing the enamel substrate 1, a part of the metal plate 3 is vertically cut and raised so that a pair of cut and raised pieces 16 and 17 face each other, and one of the cut and raised pieces 16 has a tapered surface 19 and a land. A through hole 21 having a portion 2o is provided. When mounting a tall discrete component 18, the discrete component 18 is laid down and placed between the cut and raised pieces 16 and 17.
Cut and raise the lead terminal 22 of the through hole 2 of the piece 16.
1 and soldered to the land portion 20. Note that 23 is an elastic material such as rubber for vibration absorption inserted between the discrete component 18 and the enamel substrate 1, or an adhesive for fixing the Deinucrete component.

Therefore, by using the structure of this embodiment, even the discrete component 18 having a short back can be mounted without increasing the thickness of the enamel substrate 1 when mounted. Furthermore, the heat of the discrete component 18 is transferred to the cut and raised piece 16.
Cut and raise the piece 1 through the contact surface with the lead terminal 22 and the lead terminal 22.
6, as shown in FIG. 8, the heat dissipated from the surface opposite to the lead terminal 22 is also absorbed by the opposing cut-and-raised piece 17, and the heat is absorbed from the enamel substrate 1 more efficiently. Heat is dissipated. Further, the metal plate 3 of the enameled board 1 is grounded, and a cut-and-raised piece 18 is provided between the metal plate 3 of the enameled board 1 and the surface-mounted component 24 such as another discrete component 8 mounted adjacent to the discrete component 18 or a paired chip IC.
．． 17, the electromagnetic field noise generated by the discrete component 18 itself can be grounded to the ground via the metal plate 3 of the core without spatially propagating to the surface mount components 24 such as ICs. Propagation noise can be reduced.

The embodiment of the present invention shown in FIG. 10 is similar to the embodiment of FIG. It is inserted into the through hole 21 of one cut-and-raised piece 16 and soldered, and a thermally conductive material (e.g., thermally conductive material epoxy resin, thermally conductive rubber, thermally conductive solder, etc.) 25, and can improve heat dissipation from the -layer discrete component 18.

[Effects of the Invention] According to the present invention, the heat of the discrete component can be absorbed from the lead terminal to the enamel substrate, and the heat accumulated in the package of the discrete component can also be absorbed from the bottom of the discrete component to the enamel substrate. It can be removed by absorbing heat. Moreover, since the land portion is provided on a tapered surface, the soldering area between the lead terminal and the land portion is increased, and heat absorption from the lead terminal to the enamel substrate is improved. Furthermore, the enamel quality of the surface of the enamel substrate also improves heat dissipation from the enamel substrate into the air.

As a result, the temperature rise of the discrete components can be suppressed, thermal damage to the discrete components can be prevented, and the reliability of the components can be improved. Furthermore, since heat dissipation into the air is improved and temperature rise is reduced, components with lower heat resistance standards can be used, making it possible to use smaller and cheaper discrete components.

Furthermore, since the discrete components are supported on the enamel board by the lead terminals and the bottom surface, the discrete components will be difficult to move due to vibrations and shocks, and the lead terminals will not bend or the soldering of the lead terminals will come off due to vibrations and shocks. It gets colder.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the invention, FIG. 2 is a sectional view showing a second embodiment of the invention, and FIG. 3 is a sectional view showing a third embodiment of the invention. , FIG. 4 is a sectional view showing a fourth embodiment of the present invention, FIG. 5 is an enlarged sectional view showing main parts of the fifth embodiment of the invention, and FIG. 8 is a sixth embodiment of the invention. FIG. 7 is an enlarged sectional view showing the main part of the seventh embodiment of the present invention; FIG. 8 is a sectional view showing the main part of the seventh embodiment of the present invention; 10 is a sectional view showing a ninth embodiment of the present invention, FIG. 10 is a sectional view showing a second embodiment of the present invention, FIG. 11 is a partially broken sectional view showing a conventional metal core substrate, and FIG. Figure 12 is a partially broken cross-sectional view of a conventional enamel board, Figure 13 is a cross-sectional view of the same enamel board with surface mount components and discrete components mounted, and Figure 14 shows the heat dissipation paths of the discrete components. It is a figure showing the thermal resistance. 1... Enamel board 3... Metal plate 4... Insulating layer 5... Through hole 6... Tapered surface 7... Land portion 8... Discrete component 8a... Discrete component Bottom lO...Lead terminal

Claims (1)

[Claims] (1) A through hole with at least a portion expanded into a tapered shape is provided in an enameled substrate in which the surface of a metal plate is covered with an enameled insulating layer, and a land portion is formed on the tapered surface of the through hole, A board for a discrete component, characterized in that the lead terminal of the discrete component is inserted into the through hole from the opposite side of the tapered surface, the bottom surface of the component is brought into contact with the enamel substrate, and the lead terminal is soldered to the land portion. Implementation structure for.