JPH02246142A - Semiconductor device - Google Patents

Abstract

PURPOSE:To relax a thermal stress on individual recessed parts by a difference in a coefficient of thermal expansion between a heat-dissipating body and an interposition sheet and to prevent the interposition sheet from being broken by a method wherein the heat-dissipating body and the interposition sheet are fit in such a way that a plurality of leg parts and recessed parts are mated. CONSTITUTION:A heat-dissipating body 20 made of Al is composed of a column body 21 and radiating fins 22; four leg parts 24 to 27 whose cross section is fan-shaped are arranged at equiangular intervals at peripheral parts on a bottom face 23 of the column body 21. Recessed parts 31 to 34 whose shape corresponds to said leg parts 24 to 27 are formed on the surface of an interposition sheet 30 made of CuW. The individual leg parts 24 to 27 of the heat-dissipating body 20 are fit to the corresponding recessed parts 31 to 34; the body is bonded by using a solder. By this structure, a thermal stress by which the leg part 24 exerts on a whole peripheral face part of the recessed part 31 in the interposition sheet 30 by thermal expansion is relaxed relatively; a crack is not produced at a periphery of the recessed part 31.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of semiconductor IT, especially the mounting of heat sinks, the purpose is to enable bonding of the heat sink made of metal material to the intervening plate, and the intervening plate is fixed on the semiconductor element. Further, in a semiconductor device having a structure in which a heat sink is fixed on the intervening plate, the heat dissipating body has a shape having a plurality of legs distributed around the bottom surface thereof, and the intervening plate has a plurality of legs. A recess corresponding to part a is provided, and the heat radiator has each leg fitted into the recess, and the bottom surface and the upper surface of the intervening plate, and each leg and the recess are joined by a metal material. , and is configured to be fixed to the intervening plate.

[Industrial application field]

The present invention is a semiconductor y! The location, especially the installation of the heat sink, is related to the structure.

In recent years, as semiconductor devices have become more densely packed, power consumption has been increasing, and as a result, heat generation has also tended to increase.

For this reason, there is a need for a heat dissipation structure for semiconductor devices that has better heat dissipation efficiency than conventional ones.

(Conventional Technique 1) FIG. 10 shows a conventional example similar to the semiconductor device shown in Japanese Unexamined Patent Publication No. 63-73650. Reference numeral 1 denotes a semiconductor element, which is mounted face-down on a substrate 2. 3 is a large number of bottles. A cap 4 is fitted onto the semiconductor cable 1 and fixed onto the substrate 2, sealing the periphery of the semiconductor cable 1.

Reference numeral 5 denotes an intervening plate, which is made of CuW and has approximately the same coefficient of thermal expansion as the semiconductor element 1.

This intervening plate 5 is fixed to the upper surface of the semiconductor rope 1 by screws 6.

Reference numeral 7 denotes a heat sink made of aluminum, which is bonded onto the intervening plate 5.

This joining is performed using a flexible resin material 118 in order to absorb the difference in thermal expansion between the intervening plate 5 and the heat sink 7.

The heat of the semiconductor element 1 is transferred to the screw material 6. Intervening plate 5. The heat is conducted to the heat sink 7 via the resin 8, and the heat is radiated from the heat sink 7.

(Problems to be Solved by the Invention) Here, the thermal conductivity of the resin 8 was particularly low, and the resin 8 hindered improvement in heat dissipation efficiency.

If a metal material such as solder is used instead of the resin 8, the heat radiation efficiency will improve, but since the metal material is not flexible, the joint will break due to warp due to the difference in thermal expansion coefficient, and the heat radiation body 7
will come off.

Therefore, as shown in FIG.
It is also conceivable to form a structure in which the bottom part 10 of the heat sink 7 is fitted into the recess 9 and soldered.

However, in this case, since the diameter d of the bottom part 10 of the heat sink 7 is large, the recess t' of the bottom part 10! The difference in thermal expansion with respect to the recess 9 is too large (the thermal stress acting on the recess 9 becomes large, and the intervening plate 11 may crack).

An object of the present invention is to provide a semiconductor device that allows a heat sink made of a metal material to be bonded to an intervening plate.

(Means for Solving the Problems) The present invention provides a 1! conductor device having a configuration in which an intervening plate is fixed on a semiconductor onion and a heat dissipating body is further fixed on the intervening plate. The intervening plate has a shape having a plurality of legs distributed around the portion, and the intervening plate is provided with a recess corresponding to the 111 part, and the heat dissipation body has each leg part fitted into the recess, and The bottom surface, the top surface of the intervening plate, each leg, and the recess are joined by a metal material, thereby fixing the intervening plate.

(Function) Since the heat radiator and the intervening plate have a structure in which a plurality of legs and recesses are fitted in an uneven manner, the thermal stress to each recess due to the difference in thermal -II elongation between the two is the same as that of the legs of -. - The relationship with the recessed portion is relaxed, and cracking of the intervening plate is prevented.

Since the plurality of legs are arranged around the bottom of the heat sink, free thermal expansion of the bottom of the heat sink is restricted, and the connection between the heat sink and the intervening plate cannot be achieved even if metal materials are used. There will be no cracks in this.

(Embodiment) FIGS. 1 and 2 each show a semiconductor device 20 according to an embodiment of the present invention. In each figure, parts corresponding to those shown in FIG. 10 are given the same symbols.

Reference numeral 20 denotes a heat sink made of Ac, which is composed of a cylindrical body 27 and a heat sink fin 22, as shown in FIGS. 3 and 4.
In addition, four l1 sections 24 to 27 each having a fan-shaped cross section are arranged at equal angular intervals on the circumference of the bottom surface 23 of the cylindrical body 27.

Reference numeral 30 denotes an intervening plate made of CuW, and as shown in FIGS. 5 and 6, recesses 31 to 34 having shapes corresponding to the legs 24 to 27 are formed on the upper surface.

This intervening plate 30 is fixed to the upper surface of the semiconductor element 1 by screws 6 as in the conventional case.

The heat sink 20 connects each leg 24 to 27 to a corresponding recess 31 to
34 and joined with solder 35. solder 3
5 is present on the entire circumferential surface and bottom surface of each of the lj parts 24 to 27 and on the bottom surface 23 of the cylindrical body 27.

Here, how thermal stress is absorbed according to the above configuration will be explained.

The relationship between the coefficient of thermal expansion is A>CUW.

FIG. 7(A) shows a state in which the legs 24 to 27 of the heat sink 20 and the recesses 31 to 34 of the intervening plate 30 are fitted.

As the temperature rises, each leg 24-27 follows the arrows 36a-3.
It expands in all directions as shown by 6c and becomes thicker as shown by the two-dot chain line. The intervening plate 30 also expands in all directions as indicated by arrows 37, but the outer arcuate portions of each of the recesses 31 to 34 are displaced outward.

Here, the term "outward" and "outside" refer to a direction and a portion on the arcuate side of both the leg and the recess, and "inward" and "inward" refer to a direction and a portion on the side of two sides that intersect with each other in both the leg and the recess.

Hereinafter, explanation will be given focusing on the negative leg portions 24 and the negative recesses 31.

The expansion of the leg portion 24 will be considered separately into outward expansion indicated by arrow 36a and inward expansion indicated by arrows 36b and 36C.

The magnitude of the outward expansion is greater than the magnitude of expansion in the same direction of the recess 31, and the outer portion of the recess 31 is
), the outward expansion of the legs 24 pushes them apart and stretches them beyond the thermal expansion of the inner body of the intervening plate 30.

However, since the inner part of the recess 31 is not displaced outward,
Between the inside of the leg portion 24 and the inside of the recess 31, there is an extra space indicated by the reference numeral 38.

The inward expansion of the legs 24, shown by arrows 36b, 36c,
This is done within this extra space 38.

As a result, the thermal stress applied to the entire circumferential surface of the recess 31 of the plate 30 through which the leg 24 is interposed due to thermal expansion is relatively relaxed, and no cracks occur around the recess 31.

The relationship between the other W portions 25, 26, 27 and the recesses 32, 33° 34 is similar to that with the leg portion 24 and the recess 31, and the stress in the surrounding area of each recess 32, 33, 34 is small. No cracks occur in the parts.

Next, solder 35 due to the difference in thermal expansion. In particular, the bottom surface 23 of the cylindrical plate 27
The color tube for the solder 35a between the upper surface 39 of the intervening plate 30 will be explained.

The bottom surface 23 side of the cylindrical plate 27 is 41 points above the circumference in the circumferential direction!
It is fitted with the intervening plate 30 in a concave and convex manner at the l position, thereby substantially restricting outward thermal expansion.

The cylindrical plate 27 has an inverted conical shape as shown in FIG.

Therefore, the bottom surface 23 of the cylindrical body 27 thermally expands in the same manner as the top surface 39 of the intervening plate 30.
No stress is generated in the solder 35a between 3 and the upper surface 39, and 1
Crack in solder 35a and #l between bottom surface 23 and top surface 39
There is no separation.

In addition, the above lj! ! ! If $24 to $27 are provided at a portion of the bottom surface 23 that is biased toward the center from the periphery,
The outer part of the bottom surface from the part where the legs are arranged will thermally expand freely without being constrained, causing a difference in thermal expansion with the intervening plate 30, and cracks in the solder 35a. This is not desirable as there is a possibility that this may occur.

Next, '1!' of the above configuration! Heat radiation of the conductor device 20 will be explained.

The heat of the semiconductor element 1 is absorbed by the screw material 6. Intervening plate 30. The heat is conducted to the heat sink 20 via the solder 35, and the heat is radiated from the heat sink 20. In addition, each m part 24-27 and the recessed part 31-34 are joined by the solder 35 over the entire circumference and the whole bottom surface.

The solder 35 has better thermal conductivity than the conventional resin 8, and the thermal resistance from the semiconductor element 1 to the heat sink 20 is reduced, improving heat radiation efficiency.

Also, compared to the structure in which the heat sink is placed on the instep on the intervening plate,
The contact area between the two is increased by the combined area of the circumferential surfaces of the legs 24 to 27. This also reduces the thermal resistance from the intervening plate 30 to the heat radiator 20 and improves the heat radiation efficiency.

FIG. 9 shows a semiconductor device according to another embodiment of the present invention.

This semiconductor device has an intervening plate 30A with a stepped portion 4 around the bottom surface.
0, and the cap 4A has a structure in which the m111 portion thereof extends around the upper surface of the semiconductor element 1, and the intervening plate 30A is fixed by fitting the step 140 to the inner peripheral side of the cap 4A. It is.

Note that the present invention is not limited to the case where the heat sink is made of At and the intervening plate is made of CuW, and the present invention is similarly applied even if the heat sink and the intervening plate are made of materials other than those mentioned above, and the same effects can be obtained. has. That is, according to the present invention, materials can be selected regardless of the degree of thermal expansion coefficient, especially for the heat sink.

Further, the shape of the west face of each leg is not limited to a fan shape, and may be circular, for example.

(Effects of the Invention) According to the present invention, the thermal stress due to the difference in coefficient of thermal expansion between the heat sink and the intervening plate can be layered,
It is possible to prevent the intervening plate from cracking. In addition, free thermal expansion of the bottom surface of the heat sink is restricted, so that cracking and peeling of the metal material do not occur.

By using a metal material and increasing the contact area between the heat radiating body and the intervening plate, it is possible to improve heat radiation efficiency.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway exploded perspective view of a semiconductor device according to an embodiment of the present invention, FIG. 2 is a sectional view of the semiconductor device of FIG. 1, FIG. 3 is a front view of a heat sink, and FIG. A bottom view of the heat sink, No. 5 WJ is a positive view of the intervening plate, Fig. 6 is a plan view of the intervening plate, Fig. 7 is a view showing the state of the legs and recesses during thermal expansion, and Fig. 8 is a 9 is a cross-sectional view of a semiconductor device according to another embodiment of the present invention, 10FA is a diagram showing a conventional example, and FIG. 11 is the entire bottom of the heat radiator. It is a figure which shows the example which makes a recessed part of an intervening board fit. 30 is an intervening plate, 31 to 34 are recesses, 35, 358 are solder, 36a, 36b, 36c, and 37 are arrows indicating thermal expansion, 38 is an extra space, and 39 is an upper surface. Patent applicant Fujitsu Ltd. In the figure, 1 is a semiconductor cluster, 2 is a substrate, 6 is a screw, 20 is a heat sink, 27 is a cylinder, 22 is a heat sink, 23 is a bottom surface, and 24 to 27 are legs. Section, Fig. 4 Gushu Trap f) Plain ω Group θ Fig. Broom 1 m Cow 4 Su ← Hearing J Figure 7 Figure 8 Figure 9

Claims (1)

[Scope of Claims] A semiconductor device having a structure in which an intervening plate (30) is fixed on a semiconductor element (1), and a heat dissipating body (20) is further fixed on the intervening plate (30), the heat dissipating body ( 20) is shaped to have a plurality of legs (24 to 27) distributed around its bottom surface (23), and the intervening plate (30) corresponds to the legs (24 to 27). recesses (31 to 33) are provided, and the heat sink (20) has legs (24 to 27) fitted into the recesses (31 to 33), and the bottom surface (23) and the intervening plate ( 30) top surface (39) and each leg (24 to 27)
) and the recesses (31 to 33) are made of metal material (33, 35
A semiconductor device having a configuration in which it is joined by a) and fixed to the intervening plate (30).