JPH0465193A - High density mounting heat dissipating board - Google Patents

Abstract

PURPOSE:To secure heat dissipation, high reliability and high quality by sticking a metallic thin plate excellent in thermal conductivity such as aluminum, etc., on a board by a hot press thereby radiating heat from the board at large without enlarging the total thickness of the board. CONSTITUTION:A metallic board 6 is etched so that the crosspieces 6a may hit the parts to contact with the bottom of electronic parts and that the parts where the lead wires of the electronic parts connect electrically with the circuit board may be holes, and it is joined to the board 1 with a hot press. The heat dissipating part 7 can otherwise be provided by welding the same metallic plate. Depending upon the mounting density on the board, the heat dissipating part 7 can be done without. Moreover, as a heat dissipating thin plate 6, a stainless metallic plate (42 alloy) 0.2mm is used, but aluminum or copper excellent in thermal conductivity may also be used. Since the heat dissipating area can be enlarged this way, a small-sized and thin high density mounting board can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-density mounting heat dissipation board for improving heat dissipation characteristics in a high-density mounting board for video equipment.

Conventional technologyAs video equipment becomes more sophisticated, more complex, and more personalized, multiple circuit boards with many functions are combined into a single circuit board using high-density mounting technology, making it more compact and more compact. Achieves weight reduction. Single-sided or double-sided circuit boards were used as substrates, but recently multilayer circuit boards have become popular (
It is used. Generally speaking, glass epoxy multilayer substrates are mainly used as materials due to cost considerations, and ceramic multilayer substrates are used in mobile communications (small telephones, etc.), computers, and the like. Next, as for electrical components, surface mount type components are being used in place of conventional insertion type components. A surface mount type package style is also used for semiconductor devices.

Furthermore, in terms of materials such as solder, for example, fine solder with a small solder particle size and uniform particle size distribution is used to improve printing accuracy and thereby improve packaging density.

By the way, in general, when a signal voltage is applied to an electrical component, some power loss always occurs. Therefore, when the packaging density per unit area on the board increases due to high-density packaging, the power loss per unit area on the board increases.

Since power loss ultimately becomes thermal energy, the higher the packaging density (the more heat is generated per unit area of the board).

Therefore, when attempting to significantly improve packaging density, improving heat dissipation characteristics is a major issue. Improving heat dissipation characteristics is thus an extremely important factor in the trend towards downsizing of video equipment. An example of a conventional heat dissipation method for a high-density mounting board will be described below with reference to the drawings. FIG. 3 is an example of a conventional heat dissipation method. As shown in FIG. 3, a heat sink 3 made of extruded metal material such as aluminum is attached to an electrical component 2 mounted on the surface of a substrate 1 using an adhesive 4.
By joining through the electrical parts 2, the heat generated from the electrical parts 2 is released into the air. This method has the disadvantage that the total thickness of the board after mounting is increased due to the heat sink 3.

Next, another example of the conventional heat dissipation method will be described using FIG. 4. In contrast to FIG. 3, where heat is radiated from the upper surface of the electrical component, FIG.
In this method, a metal plate 5 made of aluminum or the like with good thermal conductivity is provided so as to be in contact with the lower surface of the electric component 2, and the heat generated from the electric component 2 is transferred to the metal plate 5, and the heat is released from the end of the metal plate 5 into the air. In the example shown in FIG. 4 as well, the presence of the metal plate 5 increases the thickness, making it impossible to improve the packaging density.

Further, heat is dissipated into the air from the end of the metal plate 5, but in this case, the area of the end is small, so the heat dissipation is not large. There is also a heat conduction path through which heat is dissipated from the substrate 1 into the air via the metal plate 5, but as mentioned above, the substrate is usually a glass epoxy substrate or a ceramic substrate, which has poor thermal conductivity, so the heat is dissipated through this path. The emission of is relatively small.

Therefore, although heat dissipation is improved by the method shown in FIG. 4, there is a limit.

Problems to be Solved by the Invention The above-described heat dissipation method has no particular problem when the mounting density is low, and the mounting board is a single-sided or double-sided board. However, if a multilayer board with four or more layers is used and the mounting density is several times higher than before, the electrical components to be mounted will naturally be of the small surface mount type, making miniaturization relatively easy. However, there is a problem in that the improvement in heat dissipation characteristics described above has a limit.Therefore, there was a need for a heat dissipation method that is thin enough to accommodate increased packaging density and has sufficient heat dissipation effect. .

An object of the present invention is to provide a high-density mounting heat dissipation board that has a reduced overall thickness including a heat dissipation plate after mounting and has a high heat dissipation effect.

Means for Solving the Problems In order to solve the above problems, the high-density mounting heat dissipation board of the present invention has a thin metal plate with good thermal conductivity such as aluminum attached on the board by heat pressing, and the lead wires of the electrical components are The portion that is electrically connected to the circuit board is constructed by making holes by etching. A thin metal plate having a thickness of approximately 0.1 to 0.3I is used, and the thin plate described above is attached so as to correspond to the lower surface portion on which electrical components are mounted.

Function The present invention achieves the high heat dissipation effect of the high-density mounting board as described above in the heat dissipation configuration described above. Specifically, high reliability and high quality can be ensured without increasing the total thickness of the electrical components and the board of the high-density mounting board, and by dissipating heat throughout the board.

EXAMPLE Hereinafter, a high-density mounting board according to an example of the present invention will be described with reference to the drawings. FIG. 1 shows a high-density mounting heat dissipation board according to an embodiment of the present invention. In the figure, the third
Components that are the same as those in FIG. 4 will be described with the same reference numerals. As shown in FIG. 1, the metal plate 6 is etched so that the crosspiece 6a contacts the bottom surface of the electrical component, and a hole is formed in the portion where the lead wire of the electrical component is electrically connected to the circuit board. 1 by heat press. Heat dissipation part 7 in the figure
can also be provided by welding the same metal plate. Depending on the mounting density on the board, the heat dissipation section 7 described above may be provided, but it is also possible to provide the heat dissipation section 7.
．． 2- stainless metal plate (alloy 42) is used, but aluminum or copper, which have good thermal conductivity, can also be used. The thickness can also be changed if the packaging density is high. Note that the etched shape shown in FIG. 1 may be used by etching it into a necessary shape according to the circuit configuration.

Figure 2 is an example. Furthermore, it can be used not only on one side of the board but also on both sides by pasting it with a heat press.

Effects of the Invention As is clear from the above description of the embodiments, according to the present invention, one of the dissipation paths for the heat generated in the electrical components is that it is conducted in the direction of the thickness of the heat dissipation thin plate, and the heat is also dissipated from the board. Another path is that heat is conducted in the direction of arrow A in FIG. 1 and is radiated into the air from a heat dissipation section 7 provided at the end of the substrate. In addition, in the example in Figure 2, the direction of heat conduction is not only arrow A (arrow B
It can also be conducted in the direction of Even if the heat dissipation section 7 is not provided, the heat is dissipated into the air from the ends 8a and 8b of the dissipation plate.

As described above, according to the present invention, since the heat dissipation area can be increased, the heat dissipation characteristics from the board as a whole can be improved.This makes it possible to realize a smaller, thinner, high-density mounting board. .

[Brief explanation of drawings]

FIG. 1 is a perspective view of a high-density mounting heat dissipation board according to one embodiment of the present invention, FIG. 2 is a perspective view of a high-density mounting heat dissipation board according to another embodiment of the present invention, and FIGS. 3 and 4 are respectively FIG. 2 is a partially enlarged cross-sectional view of a conventional high-density mounting board. 6... Heat dissipation thin plate, 6a... Crosspiece of the heat dissipation thin plate, 7... Heat dissipation part of the heat dissipation thin plate. Name of agent Patent attorney Shigetaka Awano et al. 1 Loyalty 1 Figure C-・-Noyu 1 Figure 3, 3 Figure 2 Go Figure 4

Claims (1)

[Claims] (l) A circuit board and an electrical circuit on the circuit board are a mounting board consisting of a thin metal plate that is electrically insulated and bonded to the circuit board, and the thin metal plate has an electrical circuit mounted thereon. A high-density mounting heat dissipation board characterized in that a hole is made in a thin metal plate at a portion where the lead wire of the electrical component contacts the main body of the component and conducts with the circuit board. (2) The high-density mounting heat dissipation board according to claim 1, characterized in that a heat dissipation section is provided on the thin metal plate. (3) The high-density mounting heat dissipation board according to claim 1, characterized in that a heat dissipation section made of the same material as the thin metal plate is provided on the thin metal plate by welding.