JPH0851172A - Ceramic package and heat dissipation board - Google Patents

Abstract

(57) [Summary] [Object] To provide a heat dissipation substrate having a deformed shape, which has a thermal conductivity and a thermal expansion coefficient suitable for a ceramic package, is excellent in workability, and is inexpensive. [Constitution] Copper was sufficiently mixed with molybdenum powder so as to be 40 wt%, press-molded, and then sintered in hydrogen at 1250 ° C. for 2 hours. Plate materials of 0.2 mm and 2.3 mm were produced. The thermal characteristics of the heat dissipation substrate are: density 9.6 g / cm ³ , thermal conductivity 2
37 w / m · k and a coefficient of thermal expansion of 9.1 × 10 ⁻⁶ / ° C. were obtained. After that, nickel plating was applied and the parts were assembled as parts in a ceramic package. The figure shows the convex portion 4 in the center.
The modified heat dissipation board 1 of the type in which the semiconductor chip 5 is mounted is shown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, that is, a ceramic package on which a semiconductor chip is mounted, and more particularly to a ceramic package having a heat dissipation substrate.

[0002]

2. Description of the Related Art Conventionally, in this type of ceramic package, it is extremely important to efficiently dissipate heat generated from the element and its surroundings. For this reason, a heat dissipation substrate called a heat sink is incorporated in the ceramic package. It is normal to have Various heat-dissipating materials have been studied as the heat-dissipating material constituting the heat-dissipating substrate, and research and development thereof are still ongoing.

In order to meet various demands of users, it is necessary to prepare heat dissipation boards having various shapes. In order to prepare heat dissipation boards of various shapes, it is necessary to prepare not only a rectangular heat dissipation board but also a heat dissipation board having a shape other than a rectangle (here, an irregular shape). As described above, in order to prepare a heat dissipation substrate having an irregular shape, various processes such as punching,
It is desirable that the heat-dissipating material is easy to press, step, and the like. Further, it is extremely important for practical use that the deformed heat-dissipating substrate incorporated in the ceramic package is inexpensive.

As described above, there is a strong demand for a heat dissipating substrate which is excellent in workability and therefore can be easily processed into a different shape and is suitable for an inexpensive ceramic package.

Here, various shapes of the heat-dissipating substrate having an irregular shape are assumed as shown in the later-described figures, but it is often processed by cutting, slitting, polishing or the like, so that the cost is reduced. However, as long as these processing methods are mainly used, it is difficult to perform them easily.

Conventionally, it has been considered desirable that the heat sink of a ceramic package be close to a ceramic (for example, the thermal expansion coefficient of aluminum oxide is 6.7 × 10 ⁻⁶ / ° C.).

However, even in the case of the ceramic package, the peripheral members of the semiconductor chip have a thermal expansion coefficient (for example, Si of the semiconductor chip) due to the design.
4.2 × 10 ⁻⁶ / ° C.), which is considerably larger than the above.

Considering such a situation, it is possible to process at a low cost, has a high thermal conductivity, and is excellent in heat dissipation.
Despite the fact that developing a metal deformed heat sink with a coefficient of thermal expansion of 9 × 10 ^-6 / ° C or higher is a key technology that can flexibly meet the assembly specifications of ceramic packages, it is effective. Moreover, the reality is that no practical solution has been reached.

Here, copper has a thermal conductivity of 380 w / m.
k is extremely high and is excellent in workability, but the coefficient of thermal expansion is too large at 17.3 × 10 ⁻⁶ / ° C., which is not suitable. Also, Kovar has a thermal expansion coefficient of 5.3 × 10 ⁻⁶ / ° C. and is often used because of its moderate workability, but its thermal conductivity is 17 w.
/ M · k, which is not appropriate.

[0010]

As described above, the materials conventionally used for heat dissipation substrates for ceramic packages include thermal conductivity, thermal expansion coefficient and workability (punching, cutting, pressing, stepping, Shearing, punching, bending, slitting, cutting or polishing) and cost have been found to be unsuitable for producing various types of heat dissipation substrates.

Therefore, an object of the present invention is to remedy the above-mentioned drawbacks of the prior art, and the coefficient of thermal expansion of copper is 17.3 × 10 ^-6 /
Within a certain range below ℃, the thermal conductivity of copper is 380w /
An object is to provide an inexpensive heat dissipating substrate having a deformed shape, which is not far from m · k and has a certain level or more, excellent workability, and inexpensive.

[0012]

Means for Solving the Problems The inventors of the present invention diligently selected the processing conditions on the basis of a general metal processing method so that a material having a thermal conductivity and a thermal expansion coefficient of the present invention described later can be obtained. It was confirmed that punching, cutting, pressing, stepping, shearing, punching or bending were possible. In addition, if you use a heat dissipation material that can be processed into a deformed shape without cutting, among cutting or polishing, as a natural consequence,
The cost can be significantly reduced, and a ceramic package having a low-profile irregular heat sink can be assembled.

According to the present invention, in order to solve the above-mentioned problems, powders of copper and molybdenum are mixed, sintered and rolled to have a thermal conductivity of 200 w / m · k or more, and a thermal expansion coefficient. Is 9 to 16 × 10 ⁻⁶ / ° C. (preferably 9 to 13)
x10 ^-6 / ℃), a ceramic package that incorporates a heat dissipation substrate that has been deformed by one or a combination of punching, cutting, pressing, stepping, shearing, punching or bending. can get.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Three embodiments of the present invention will be described with reference to the drawings.

First, the first embodiment will be described.

After sufficiently mixing with molybdenum powder so that the copper content becomes 40 wt%, and after press molding, it is carried out in hydrogen at 1250 ° C. × 2.
The material that had been sintered for a period of time was hot-rolled and cold-rolled to produce plate materials having a thickness of 1.2 mm and 2.3 mm.

By using a die punching press on a plate having a thickness of 1.2 mm, the plate-shaped irregular heat dissipation substrate 1 shown in FIGS. 1 and 2 was obtained. In addition, 2 is roundness and 3 is a notch.

Further, a 2.3 mm thick plate was punched into a rectangle, rounded at four corners to form a deformed shape, and then the convex portion 4 in FIG. 3 was machined by cutting. It could be machined at a speed of 4 to 5 times, and at a speed almost similar to that of oxygen-free copper.

Therefore, regarding the processing cost,
We were able to fabricate a heat-dissipating board with an irregular shape using an extremely low-cost method.

Important thermal properties as a heat dissipation substrate are as follows: density of 9.6 g / cm ³ , thermal expansion coefficient of 9.1 × 10 ^-6 / ° C., thermal conductivity of 237 w / m.
It was possible to obtain k and meet the user's request.

After that, nickel plating was applied and the parts were assembled as parts in a ceramic package. Although there are various configurations of ceramic packages, the one that directly contacts the heat dissipation board with the semiconductor chip, the one that is used as the lid (cap), and the lid as the metal heat dissipation board are based on the difference in thermal expansion. There is also one that intentionally joins the semiconductor chips to achieve design matching such as heat balance of the entire package.

Here, in FIG. 4, a convex portion 4 is formed in the center,
FIG. 5 shows a case where a modified heat dissipation board 1 of the type in which the semiconductor chip 5 is mounted on the convex portion 4 is used, while FIG. 5 shows a modified heat dissipation board 1 having a convex portion 4 formed on the periphery as a package lid.
Shows the one using. It was found that these convex portions can be easily formed by pressing, and any of them can be applied as a modified heat dissipation substrate.

Next, a second embodiment will be described.

After sufficiently mixing with molybdenum powder so that the copper content becomes 50 wt%, and press-molding, 1200 ° C. × 2 in hydrogen.
What was sintered for time was hot-rolled and cold-rolled to produce a plate material having a thickness of 1.0 mm.

The peripheral rectangular portion shown in FIGS. 1, 2, 6 and 7 was processed by a die punching press.

The deformed heat dissipation substrate 1 of FIG. 6 has holes 6 punched at its four ends, and the deformed heat dissipation substrate 1 of FIG. 7 is bent at the center by pressing or chucking. The bent convex portion 7 is provided.

The thermal characteristics are a density of 9.5 g / cm ³ , a thermal expansion coefficient of 11.0 × 10 ^-6 / ° C., and a thermal conductivity of 253 w / m · k.
Was obtained and evaluated in the same manner as in Example 1, and the usefulness was confirmed.

Next, a third embodiment will be described.

After sufficiently mixing with molybdenum powder so that the copper content is 60 wt%, press-molding, and sintering in hydrogen at 1150 ° C. for 2 hours, hot rolling and cold rolling are performed to obtain a thickness of 1. A 5 mm plate material was prepared.

In order to mount a semiconductor chip, if a part of the heat sink is formed into a convex portion 4 (FIG. 3) or a bonding wire pad is formed into a convex portion of 0.1 to 0.15 mm, it is possible to carry out integral press working. Although it is possible to contribute to the reduction of processing cost, when the plate material having the thickness of 1.5 mm is subjected to plastic working by a die press, the modified heat dissipation substrate 1 shown in FIGS. 3, 8 and 9 is obtained.

Further, when the volume of the concave portion 8 in FIG. 8 is large, a convex portion may occur at one end portion of the concave portion 8 in the plate thickness direction, and the convex portion generated as a whole in the modified heat dissipation substrate 1. Cannot be absorbed. At this time, since the plate material according to this embodiment has extremely good workability, the convex portion can be removed by cutting. As described above, since the plate material in this embodiment can be cut, the deformed heat dissipation board 1 can be manufactured at low cost.

The thermal characteristics of the plate material according to Example 3 are the density 9.
It was possible to obtain 4 g / cm ³ , a coefficient of thermal expansion of 12.3 × 10 ⁻⁶ / ° C., and a thermal conductivity of 272 w / m · k, and evaluation was performed in the same manner as in Example 1 to confirm its usefulness.

The hardness and Erichsen value of a composite material obtained by sintering a powder containing 40%, 50%, and 60% of copper in molybdenum are used as a measure of the workability of the modified heat dissipation substrate. Shown in 1.

[0034]

[Table 1]

It can be seen from Table 1 that the above-mentioned composite material exhibits an Erichsen value of 4 or more, although it is a composite material.

When a composite rolled material containing 35 wt% of copper was also tried, the coefficient of thermal expansion was 8.4 × 10 ⁻⁶ / ° C. although the thermal conductivity did not reach 200 w / m · k. It has been found that at least punching is possible among the various processes, and cutting is also excellent.

Also in the heat sink for the individual semiconductor laser device 9 relating to microwaves and the like, the assembly design condition is 40% by weight of molybdenum composite material having a coefficient of thermal expansion slightly larger than that of beryllium oxide, that is, the modified heat dissipation substrate 1 of the first embodiment. Once arranged, the present invention is adaptable, which is shown in FIG.

[0038]

Industrial Applicability A package on which a semiconductor element is mounted, particularly a ceramic package excellent in reliability, sometimes obstructs the ultimate goal of generalization and contribution to industrial development if the mass production cost is high.

According to the present invention, the ceramic package having the above-described structure, in which the irregular heat dissipation substrate having a thermal conductivity of a certain value or more and a thermal expansion coefficient of a certain range, excellent workability and low cost, is incorporated. It can be provided and the convenience can be significantly improved.

[Brief description of drawings]

FIG. 1 is a front view of a first variant heat dissipation board in Examples 1 and 2 of the present invention.

FIG. 2 is a front view of a second variant heat dissipation board in Examples 1 and 2 of the present invention.

FIG. 3 is a third and third embodiment of the first embodiment of the present invention.
FIG. 5 is a front view and a cross-sectional view of a first variant heat dissipation board in FIG.

FIG. 4 is a sectional view of a fourth variant heat dissipation board on which a semiconductor chip according to the first embodiment of the present invention is mounted.

FIG. 5 is a cross-sectional view of a fifth variant heat dissipation substrate used as a package lid in the first embodiment of the present invention.

6A and 6B are a front view and a cross-sectional view of a third variant heat dissipation board in Embodiment 2 of the present invention.

FIG. 7 is a front view and a cross-sectional view of a fourth variant heat dissipation board according to a second embodiment of the present invention.

FIG. 8 is a front view and a cross-sectional view of a second variant heat dissipation board according to a third embodiment of the present invention.

9A and 9B are a front view and a cross-sectional view of a third variant heat dissipation board according to a third embodiment of the present invention.

FIG. 10 is a perspective view of a sixth variant heat dissipation board on which the semiconductor laser device according to the first embodiment of the present invention is mounted.

[Explanation of symbols]

 1 Deformed Heat Dissipating Board 2 Roundness 3 Notch 4 Protrusion 5 Semiconductor Chip 6 Hole 7 Bending Convex 8 Recess 9 Semiconductor Laser Device

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication H01L 23/14 C (72) Inventor Yoshihiko Doi 6-40-1 Aoto, Katsushika-ku, Tokyo Tokyo Tangsten Co., Ltd. Inside Tokyo Works

Claims (2)

[Claims] 1. A ceramic package used for mounting a semiconductor device, which is formed by mixing powders of copper and molybdenum, sintering and rolling, and having a thickness of 200 w / m.multidot.
A ceramic package, which has a thermal conductivity of k or more and a thermal expansion coefficient of 9 to 16 × 10 ⁻⁶ / ° C., and is provided with a heat dissipation substrate processed into an irregular shape. 2. A heat dissipation substrate used in a ceramic package, which is formed by mixing powders of copper and molybdenum, sintering and rolling, and having a thermal conductivity of 200 w / m · k or more and a thermal expansion coefficient of 200 w / m · k or more. Punching at 9-16 × 10 ^-6 / ° C.
A heat dissipation board characterized by being processed into an irregular shape by combining one or more of cutting, pressing, stepping, shearing, punching, and bending.