JPH03132059A - Ic mounting - Google Patents

Abstract

PURPOSE:To suppress temperature increase in an IC and peripheral circuits and then prevent deterioration of characteristics and reduction in reliability by transmitting heat generated within the IC through the grounding terminal and IC mold part of the IC to a printed-circuit board conductor or a metal plate and radiating heat from a chassis or a metal cover to the outside. CONSTITUTION:A hole for inserting a metal plate 8 is provided near an IC element and a metal plate 3 is inserted into a printed-circuit board 1 through a hole 8 and is soldered to a grounding conductor 4 or 5 and is allowed to contact the upper surface of the mold of the element 2. A metal plate 3 is curved and made to be elastic and a silicon adhesive material is sandwiched between it and a mold part for improving cooling efficiency. Also, the metal plate 3 is connected to a metal cover 9, heat generated within the element 2 is propagated to a cover 9 from a metal plate through the upper-surface grounding conductor 4, a through-hole 7, and the lower-surface grounding conductor 5 and is radiated to the outside. Also, heat radiated from the mold part is propagated directly to the metal plate 3 at the upper part and from the conductor 4 to the metal plate 3 for radiating heat to the outside.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for mounting an IC in a high frequency circuit.

[Conventional technology]

Conventionally, electronic circuits with electronic components mounted on printed circuit boards have been commonly used, but as the development of large-scale ICs that integrate the electronic components described above progresses, the current consumption of the ICs increases and the heat generated by the ICs increases. It has come to have an impact on the characteristics and reliability of ICs and peripheral circuits. One method of heat dissipation from an IC is to attach heat dissipation fins to the molded part of the IC, and use convection of surrounding air to dissipate the heat generated by more than 9 ICs. Also, JP-A-55-4656
As described in No. 2, there is also a method of dissipating heat to a multimetallic substrate by providing a thin insulating layer on a metallic substrate and mounting an electronic circuit thereon.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, in the case of a high-frequency circuit, the heat dissipation fin is surrounded by a shield chassis, so convection is difficult to occur around the heat dissipation fin, and a sufficient heat dissipation effect cannot be obtained. Furthermore, since a metal conductor is generally used for the heat dissipation fin, there is a problem in that high frequency signals are easily radiated to the surroundings via the heat dissipation fin.

In addition, the method using a metallic substrate is higher in cost than electronic circuits using conventional printed circuit boards, and is also heavy and
Processing method 1: There was a problem in that the degree of freedom in design was reduced when creating a double-sided substrate.

SUMMARY OF THE INVENTION An object of the present invention is to take into account the problems of the prior art described above, and to propose a mounting method that uses a conventional printed circuit board to efficiently dissipate heat from an IC, and also takes into consideration high frequency shielding of the IC.

[Means to solve the problem]

In order to achieve the above objective, the ground conductor area of the IC mounting part of the board is increased, and a metal plate is provided that is connected to the board near the IC, contacts the molded part of the IC, and also contacts the chassis or metal cover. .

[Effect]

Heat generated by the IC is transmitted to the ground terminal of the IC to the ground conductor of the board, and is radiated to the outside of the chassis or metal cover via a metal plate installed near the IC. Also, I
The heat radiated from the molded portion of C is transmitted to the metal plate in contact with the molded portion of the IC and the substrate ground conductor disposed below the IC, and is radiated to the outside through the chassis or metal cover in the same manner as p1. Therefore, by the above method, it is possible to suppress the temperature rise of the 9 IC and the peripheral circuits, and it is possible to prevent deterioration of characteristics and reliability.

Further, since the IC is provided with metal plates on the top and side surfaces, radiation of high frequency signals can be suppressed, and high frequency isolation with peripheral circuits is improved.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 2 is a top view of a board on which an IC is mounted, viewed from above, and FIG. 1 is a cross-sectional view of a mounted circuit using the board of FIG. 2, cut along the plane II'. In the figure, 1 is a board, 2 is an IC, 3 is a metal plate, 4 is a ground conductor on the top surface of the board, 5 is a ground conductor on the bottom surface of the board, 6 is a bottom wiring conductor, and 7 is a ground conductor on the bottom surface of the board.
8 is a through hole, 8 is a metal plate insertion hole, 9 is an upper metal cover 10 is a lower metal cover, and 11 is an upper wiring conductor. I
C2 is installed on the board 1 from the top surface of the board 1, and each terminal of the IC is connected to the top ground conductor 4 or the top wiring conductor 11, and is also connected to the bottom ground conductor 5 or the bottom wiring conductor 6 via the through hole 7. ing. 9. As shown in FIG. 2, the upper surface ground conductor 4 is widely disposed in and around the device section of the IC 2. Further, an insertion hole 8 for inserting a metal plate is provided near the IC 2, and the metal plate 5 is inserted into the board 1 through the insertion hole 8, soldered to the ground conductor 4 or 5, and attached to the upper surface of the mold of the IC 2. It is arranged so that it comes in contact with the The metal plate 5 is curved to have elasticity so as to be in uniform contact with the IC 2, and a heat conductor with good adhesion, such as a silicone adhesive or a silicone rubber sheet, is sandwiched between the IC mold part and the metal plate. In particular, efforts are being made to improve heat dissipation efficiency. Further, the metal plate 5 is also connected to the metal cover 9. The heat generated inside the IC2 is transferred from the ground terminal to the top ground conductor 4, through hole 7,
The heat is transmitted to the lower surface ground conductor 5, and is transmitted to the metal plate 3 and the metal cover, and is radiated to the outside. In addition, the heat radiated from the molded part of the IC is transmitted upward to the metal plate 3), downward to the upper ground conductor 4 and to the metal plate 3, and similarly, the heat is radiated to the outside through the metal cover 9. Ru. Therefore, the heat generated in IC2 is radiated to the outside via the ground conductor and metal plate, and
It is possible to prevent characteristic deterioration of the C and peripheral circuits due to heat. In addition, since IC2 is surrounded by a ground conductor at the top and bottom, it is possible to reduce the radiation of high-frequency signals to the outside, and it is also separated from external circuits by a ground conductor and metal plate, making it possible to prevent high-frequency isolation. Since the performance is good, the present invention is an effective method for high-density packaging using high-frequency ICs. Note that in this embodiment, two ICs facing each other
Although metal plates are arranged in the directions, the same effect can be obtained by placing the metal plates in only one direction, or in some b, five or more directions, depending on the IC shape and circuit conditions. Further, in this embodiment, the metal plate connecting the cover 9 and the substrate 1 and the metal plate contacting the molded part of the IC are integrated, but the same effect can be obtained even if they are made separately.

Next, FIG. 3 shows an embodiment using a single-sided printed circuit board. In this figure, parts having the same functions as those in FIGS. 1 and 5 are given the same symbols and their explanations are omitted. The embodiment shown in FIG. 5 differs from the embodiment shown in FIG. 1 in that the metal plate insertion hole 8 is not provided in the board 1, and the metal plate 3 is placed on the top surface of the board 2 and soldered to the top surface ground conductor 4. As in the embodiment shown in FIG. 1, the heat dissipation and high frequency shielding effects of the IC can be obtained.

FIGS. 4 and 5 show other embodiments in which the present invention is applied to a single-sided board and a double-sided board. Components in this figure that have the same functions as those in FIGS. 1 and 3 are given the same symbols and their explanations will be omitted. The present embodiment is characterized in that the contact area between the chassis 5 and the metal cover 9 is increased to improve heat transfer to the metal cover 9, thereby increasing heat dissipation efficiency.

FIG. 6 shows another embodiment of the present invention, in which parts having the same functions as those in FIG. 1 are given the same symbols and their explanations are omitted.
It is a piece of tongue that sticks out. In this example, a part of the shield plate used for the high frequency shield is cut out and used as a tongue piece.
It is used for heat dissipation of C. There is no need to provide a metal plate exclusively for the IC, and the heat dissipation and high frequency shielding effects can be obtained with a simple structure.

FIG. 7 shows another embodiment of the present invention, in which parts having the same functions as those in FIG. 1 are given the same symbols and their explanation will be omitted.

This embodiment is an example in which the metal plate 3 is brought into contact with the lower metal cover 10 to radiate heat, and has the same effect as the embodiment shown in FIG. 1.

In the above embodiments, the metal plate 5 and the metal cover 9 or 10 are connected by butting or contacting with a claw, but the metal plate 3 is fixed mechanically by drilling a hole in the metal cover and protruding, or by soldering. Attachment can be made by multiple connections, etc.
Thermal conductivity from the metal plate 3 to the metal cover is further improved. Further, although this embodiment shows an example in which the heat generated in the IC is transferred to the metal cover and radiated, the same effect can be obtained even if the heat is transferred to the chassis and radiated. Although not specifically described in this embodiment, the IC 2 and the metal plate 5 are provided between the substrate 1 and the IC 20.
The heat dissipation efficiency of the IC can be further improved by inserting a thermal conductor with good adhesion used in the contact portion of the IC.

〔Effect of the invention〕

According to the present invention, the heat generated inside the IC is radiated to the outside through the ground terminal of the IC and the IC mold part, the conductor of the board or the metal plate, the chassis, or the metal cover. temperature rise can be suppressed, and characteristic deterioration and reliability deterioration due to temperature rise can be prevented. Furthermore, by placing a metal plate in contact with the top of the IC, high-frequency signals radiated from the IC can be suppressed, and the frequency circuit can be separated by the board grounding conductor and metal plate, making it possible to implement a mounting method with excellent high-frequency characteristics. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is a cross-sectional view of one embodiment of the present invention.
Top view of the IC mounting board shown in the figure, Figures 3 and 4
5, 6, and 7 are cross-sectional views of other embodiments of the present invention. １・・・・・・・・・Substrate, ２・・・・・・・・・
IC, 5...Metal plate, 4,5...
......Grounding conductor, 7...Through hole, 9.10...Metal cover
12・・・・・・・・・Tongue piece.

Claims (4)

[Claims] 1. A circuit board having at least one IC mounted thereon;
A method for mounting an electronic device comprising a chassis frame to which the circuit board is attached, a metal cover covering the chassis frame, and a metal plate in contact with the circuit board and the chassis frame or metal cover, A method for mounting an IC, characterized in that a ground terminal of the IC is connected to the metal plate via a ground conductor arranged on a circuit board, and the metal plate is also in contact with a molded part of the IC. 2. 2. The IC mounting method according to claim 1, wherein the circuit board has a ground conductor widely disposed in the IC mounting section. 3. In claim 1, the contact portion between the metal plate and the IC mold portion is characterized in that the metal plate has elasticity.
How to implement C. 4. 2. The IC mounting method according to claim 1, wherein the molded portion of the IC is brought into contact with the metal plate via a heat conductor with good adhesion.