JPH04361561A - Ic chip mounting structure - Google Patents

Abstract

PURPOSE:To enable an IC chip mounting structure to be enhanced in heat dissipating properties. CONSTITUTION:An IC chip mounting structure is composed of a printed wiring board 13 provided with an opening window 11 located at a predetermined part where an IC chip is mounted, a metal plate 14 bonded to the board 13, and a heat pipe 18 provided with a heat dissipating fin at its end and installed bearing against the metal plate 14. An IC chip 10 is mounted on the metal plate 14 inside the opening window 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC chip mounting structure, and more particularly to a mounting structure with improved heat dissipation.

[0002] In recent years, IC chips have become highly integrated in order to be miniaturized. Also, power consumption is increasing due to increased speed. Due to these factors, IC chips generate a large amount of heat, and there is a need for a mounting structure that can dissipate heat more efficiently.

0003

2. Description of the Related Art FIG. 11 shows a conventional example.

[0004] 1 is an IC chip, and a printed wiring board 2
Die bonded on top. 3 is a wire;
It is bonded to a pad 4 on the IC chip 1 and a pad 5 on the printed wiring board 2.

[0005] The heat generated in the bare IC chip 1 is
As shown by arrow 7, the heat is radiated directly into the air, and as shown by arrow 7, it is transmitted into the printed wiring board 2, and as shown by arrow 8.
Heat is radiated into the air as shown in .

[0006]

[Problems to be Solved by the Invention] Although the heat dissipation shown by the arrow 6 is performed relatively efficiently, since the printed wiring board 2 is made of synthetic resin and has poor thermal conductivity, the printed wiring board 2 side, that is, the IC Heat dissipation efficiency from the mounting surface side of the chip 1 is not good.

The temperature distribution near the IC chip 1 is as shown by line I.

[0008] For this reason, the IC chip 1, which generates a particularly large amount of heat,
In this case, the temperature of the IC chip 1 becomes as high as T1° C., which shortens the life span and reduces reliability.

An object of the present invention is to provide an IC chip mounting structure with improved heat dissipation.

0010

[Means for Solving the Problems] FIG. 1 shows the basic configuration of the present invention.

As shown in the figure, the IC chip mounting structure of the present invention includes a printed wiring board 13 having an opening window 11 in a portion where an IC chip 10 is to be mounted, and a printed wiring board 13 that is exposed in the opening window 11. a metal plate 14; an IC chip 10 mounted on the metal plate 14 within the opening window 11; and a metal plate 1
The heat pipe 18 is provided in contact with the lower surface of the heat pipe 4.

0012

[Function] Opening window 11 of printed wiring board 13 and metal plate 1
4 acts to enable the IC chip 10 to be mounted on the metal plate 14.

The state in which the bare IC chip 10 is mounted within the opening window 11 acts so as not to impede heat dissipation into the air as shown by the arrow 19.

The metal plate 14 acts to reduce the resistance of heat conducted from the lower surface of the IC chip 10 to the heat pipe 18 side as shown by the arrow 20, and also to direct the heat in the surface direction as shown by the arrow 21. It acts to spread widely.

The heat pipe 18 acts to reduce the resistance to heat conduction as shown by the arrow 22.

As a result, the heat generated within the IC chip 10 is well conducted to the surroundings, and the temperature distribution near the IC chip 10 becomes as shown by line II.
The temperature T2°C can be suppressed to a lower temperature than the conventional temperature T1°C.

[0017]

Embodiment FIGS. 2 and 3 show a first embodiment of the IC chip mounting structure of the present invention.

Reference numeral 30 denotes a printed wiring board, which has opening windows 31 and 32 in a portion where an IC chip is to be mounted. Furthermore, pads 33 and 34 are provided at portions of the printed wiring board 30 facing the opening windows 31 and 32.

A copper plate 35 is bonded to the lower surface of the printed wiring board 30 and exposed through the opening windows 31 and 32.

36 and 37 are IC chips, and the opening window 3
1 and 32, and is mounted on a copper plate 35 by a conductive adhesive layer 38.

The IC chips 36 and 37 have pads 4 on their upper surfaces.
It has 0.41.

A wire 42 is bonded to and interposed between pads 33 and 40.

Wire 43 is bonded to pads 34 and 41 and is sandwiched between them.

A heat pipe 44 has a radiation fin 45 fixed to one end, and has a flat circular cross section as shown in FIG.

This heat pipe 44 has screws 46 and 47.
The copper plate 3 is attached by the mounting bracket 48 screwed by
5, the IC chips 36 and 37 are mounted in a pressed position.

Reference numerals 50 and 51 are electronic components that generate less heat, and are surface mounted on the upper surface of the printed wiring board 30.

Next, heat radiation in the above structure will be explained with reference to FIG.

■Top surfaces 36a, 3 of IC chips 36, 37
A part of the heat generated within the heat dissipating IC chips 36 and 37 from the side 7a is dissipated into the air as shown by arrows 60 and 61 in FIG.

■Lower surfaces 36b, 3 of IC chips 36, 37
A part of the heat generated in the heat dissipating IC chips 36 and 37 from the side 7b first reaches the inside of the copper plate 35 through the conductive adhesive layer 38, as shown by arrows 62 and 63 in FIG.

The heat reaching the copper plate 35 is conducted within the copper plate 35 in the thickness direction as well as in the plane direction, as shown by arrows 64 and 65, and reaches the heat pipe 44.

Since copper has high thermal conductivity, heat is well conducted within the copper plate 35 and widely in the plane direction.

The heat reaching the heat pipe 44 is
As shown by arrow 67, the heat is conducted well in the heat pipe 44, and as shown by arrow 67, the heat is radiated into the air from the heat radiation fins 45.

As can be seen from the above, the IC chips 36,
The heat generated inside 37 is transferred to the upper surfaces 36a, 37a and the lower surface 3
The heat is well radiated from both side surfaces on the 6b and 37b sides, and the heat radiated from the lower surfaces 36b and 37b spreads widely in the surface direction within the copper plate 35.

Therefore, the temperature distribution near the IC chips 36 and 37 becomes as shown by line III, which is gentler than before, and the maximum temperatures T3°C and T4°C inside the IC chips 36 and 37 are lower than before. lower than that of

FIGS. 5 and 6 show a second embodiment of the invention.

This embodiment has the same structure as the first embodiment described above, except that the mounting bracket is provided with radiation fins, and corresponding parts are designated by the same reference numerals and their explanations will be omitted. .

[0037] Reference numeral 70 denotes a mounting bracket, which includes heat radiation fins 70a.
It has integrally.

The two heat pipes 44 are attached to the mounting bracket 70.
It is pressed against the copper plate 35 by being pressed by.

The heat generated from the IC chip 36 and spread to the copper plate 35 as shown by arrow 62 passes through the heat pipe 44 and reaches the radiation fin 45 as shown by arrows 66 and 67.
The heat is radiated into the air, conducted through the mounting bracket 70 as shown by arrow 71, and radiated into the air through the heat radiation fins 70a as shown by arrow 72.

According to this embodiment, the IC chips 36, 37
The heat is radiated more efficiently than in the first embodiment.

FIGS. 7 and 8 show a third embodiment of the present invention.

[0042] This embodiment and the next embodiment have a structure in which heat pipes dissipate heat from the IC chips on both sides.

As shown in FIG. 8, the copper plate 35 (printed wiring board 30) and the copper plate 35A (printed wiring board 30A) are placed in a state in which a heat pipe 44 is sandwiched between them, and the gap between them is filled with prepreg 80. Fixed.

Heat from the IC chips 36 and 37 on the upper surface side is radiated through the copper plate 35, and heat from the IC chips 36A and 37A on the lower surface side is radiated through the heat pipe 44 through the copper plate 35A.

FIGS. 9 and 10 show a fourth embodiment of the present invention.

The printed wiring boards 30 and 30A have flat tubes 90 made of copper at the opening windows 31 and 31A.
They are fixed with prepreg 91 sandwiching them in between and filling the gap therebetween.

Flat plate portions 90a and 90b of the tube 90 are exposed through the opening windows 31 and 31A.

The IC chips 36, 36A are mounted on the flat plate portions 90a, 90b.

The heat pipe 44 is inserted and attached into the tube 90 described above.

The heat from the IC chip 36 on the upper surface side passes through the flat plate part 90a of the tube 90, and the heat from the IC chip 36A on the lower surface side passes through the heat pipe 44 via the flat plate part 90b of the tube 90. heat is dissipated.

Note that instead of the copper plates 35, 35A and the copper tube 90, plates or tubes made of 42 alloy or Kovar may be used.

Furthermore, AuSn or PbSn may be used instead of the conductive adhesive layer for mounting the IC chip.

[0053]

As explained above, according to the invention of claim 1, the heat of the IC chip can be radiated from both the surface side and the surface side on which it is mounted. Heat can be dissipated well.

[0054] As a result, heat can be sufficiently radiated even from an IC chip that generates a large amount of heat due to high-speed operation, and a rise in temperature can be suppressed.

As a result, it is possible to improve the reliability of an IC chip that generates a large amount of heat when it is mounted.

According to the second aspect of the invention, heat is also radiated from the mounting fittings, so that the heat of the IC chip can be radiated even better.

[0057] In the third aspect of the invention, the heat of the IC chips disposed across the heat pipe can be effectively radiated.

[0058] According to the fourth aspect of the invention, the heat of the IC chips disposed across the heat pipe can be effectively radiated.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle configuration of an IC chip mounting structure according to the present invention.

FIG. 2 is a front view of the first embodiment of the invention.

FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2;

FIG. 4 is a diagram illustrating heat dissipation from the IC chip in FIG. 2;

FIG. 5 is a front view of a second embodiment of the invention.

6 is a cross-sectional view taken along line VI-VI in FIG. 5; FIG.

FIG. 7 is a front view of a third embodiment of the present invention.

8 is a cross-sectional view taken along line VIII-VIII in FIG. 7; FIG.

FIG. 9 is a front view of a fourth embodiment of the present invention.

FIG. 10 is a cross-sectional view taken along line XX in FIG. 9;

FIG. 11 is a diagram showing a conventional example.

[Explanation of symbols]

10 IC chip 11 Opening window 13 Printed wiring board 14 Metal plate 18 Heat pipes 19, 20, 21, 22 Arrow 30 indicating heat radiation
Printed wiring boards 31, 32 Opening windows 33, 34 Pad 35 Copper plates 36, 37 IC chip 38 Conductive adhesive layers 40, 41 Pads 42, 43 Wire 44 Heat pipe 45 Radiation fins 46, 47 Screw 48 Mounting fittings 64, 65 Copper plate Arrow 70 showing the flow of heat inside Mounting bracket 70a Radiation fins 80, 91 Prepreg 90 Tubes 90a, 90b Flat plate part

Claims (4)

[Claims] Claim 1: A printed wiring board (13) having an opening window (11) in a portion where an IC chip is to be mounted; a metal plate (14); and an IC chip (10) mounted on the metal plate (14) within the opening window (11).
), and a heat pipe (1) provided in contact with the metal plate (14) at the location of the mounted IC chip.
8) An IC chip mounting structure characterized by having a configuration consisting of the following. 2. The heat pipe according to claim 1, further comprising a mounting fitting (70) for attaching the heat pipe in contact with the metal plate, and the mounting fitting has a radiation fin (70a). Mounting structure of the described IC chip. 3. An opening window (31, 31A) is provided at a portion where an IC chip is to be mounted, and a metal plate (35, 3) is provided on the back surface.
Two printed wiring boards (30
, 30A) are fixed by the metal plates (35, 35A) with the heat pipe (44) sandwiched between them, and the metal plates (35, 30A) in the opening windows (31, 31A) of each printed wiring board are
, 35A), and an IC chip (36, 36A) mounted thereon. [Claim 4] Two printed wiring boards (
30, 30A) inserts the flat metal tube (90) into which the heat pipe is inserted into the opening window (31, 31A).
are sandwiched and fixed facing the flat plate portions (90a, 90b) of the tube, and the opening windows (31, 31,
31A) on the flat plate part (90a, 90b)
Chips (36, 36A) are mounted and the tube (9
0) A mounting structure for an IC chip, characterized in that a heat pipe (44) is inserted into the IC chip mounting structure.