JP2973170B2 - Ceramic package and heat dissipation board - Google Patents

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 having a semiconductor chip mounted thereon, and more particularly, to a ceramic package having a heat radiating substrate having a step.

[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 ceramic substrate is provided with a heat radiating substrate called a heat sink. It is normal that there is. Various heat dissipating materials have been studied as heat dissipating materials constituting the heat dissipating substrate, and the 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 heat dissipation board having a rectangular shape but also a heat dissipation board having a shape having a step. Thus, in order to prepare a heat dissipation board having a shape having a step, various processes, for example, punching, pressing, desirably a heat dissipation material that can be easily processed, etc.
Furthermore, in the case of a heat-dissipating substrate having a step that is incorporated in a ceramic package, it is extremely important in practice to be inexpensive.

[0004] As described above, the workability is excellent, so that it is easy to work into a shape having a step.
There is a strong demand for a heat dissipation substrate suitable for an inexpensive ceramic package.

[0005] Here, various shapes as shown in the figures to be described later are supposed to be applied to the heat-radiating substrate having a shape having a step. However, cutting, slitting, polishing and the like are often used to reduce the cost. It is difficult to carry out the method easily as long as these processing methods are mainly used.

Heretofore, it has been considered that the heat sink of the ceramic package desirably approximates ceramic (for example, the thermal expansion coefficient of aluminum oxide is 6.7 × 10 ⁻⁶ / ° C.).

However, even in the case of a ceramic package, due to the design of the peripheral members of the semiconductor chip, the thermal expansion coefficient of the semiconductor chip is limited to the thermal expansion coefficient of the semiconductor chip (for example, Si
(4.2 × 10 ⁻⁶ / ° C.) in some cases.

[0008] In consideration of such a situation, processing can be performed at low cost, high heat conductivity, excellent heat dissipation, and
Developing a heat sink having a metal step having a thermal expansion coefficient of 9 × 10 ⁻⁶ / ° C. or more is a key technology that can be flexibly adapted to ceramic package assembly specifications. In fact, it has not been effective yet yet a practical solution.

Here, copper has a thermal conductivity of 380 w / m ·
Although it is extremely high as K and excellent in workability, the coefficient of thermal expansion is too large at 17.3 × 10 ⁻⁶ / ° C., which is not appropriate. Kovar has a coefficient of thermal expansion of 5.3 × 10 ⁻⁶ / ° C. and is moderately workable, and is often used.
/ M · K, which is not appropriate.

[0010]

As described above, the materials conventionally used for the heat dissipation board for a ceramic package include thermal conductivity, thermal expansion coefficient, and workability (punching, cutting, pressing, stepping, It has been found that shearing, punching, bending, slitting, cutting or polishing) and costs are unsuitable for producing a heat dissipation substrate having various steps.

Therefore, an object of the present invention is to remedy the drawbacks of the above-mentioned prior art and to achieve a coefficient of thermal expansion of 17.3 × 10 ⁻⁶ / copper of copper.
Within a certain range below ℃, the thermal conductivity of copper is 380 w /
An object of the present invention is to provide a heat dissipation substrate having a shape that has a step that is not far from m · K and is not less than a certain value, is excellent in workability, and is inexpensive.

[0012]

Means for Solving the Problems The present inventors have carefully selected the processing conditions based on a general metal processing method, so that the material having a thermal conductivity and a thermal expansion coefficient of the present invention described below can be obtained. It was confirmed that punching, cutting, pressing, stepping, shearing, punching, and bending were possible. In addition, among the cutting or polishing, if a heat radiating material that can be processed into a shape having a step without at least cutting is used, as a natural consequence, the cost can be greatly reduced, and a heat sink having a low-cost step is provided. A ceramic package can be assembled.

According to the present invention, in order to solve the above-mentioned problems, copper and molybdenum powders are mixed, sintered, and rolled, and have a thermal conductivity of 200 w / m · K or more and a thermal expansion coefficient of at least 200 w / m · K. Is 9-16 × 10 ⁻⁶ / ° C. (preferably 9-13
× 10 ^-6 / ° C) and incorporates a heat sink substrate that has been processed into a stepped shape by one or a combination of punching, cutting, pressing, stepping, shearing, punching or bending. Ceramic package is obtained.

[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 sufficient mixing with molybdenum powder so that the copper content is 40 wt%, press molding, and then in hydrogen at 1250 ° C. × 2
Hot sintering and cold rolling were performed on the sintering for a time to produce sheet materials having thicknesses of 1.2 mm and 2.3 mm.

Further, a plate having a thickness of 2.3 mm was punched into a rectangular shape by a die punching press, and then rounded at four corners, and the convex portion 4 of FIG. 1 was processed by cutting.
It was possible to process at a speed 4 to 5 times that of a molybdenum mill and at a speed almost similar to that of oxygen-free copper.

Therefore, the processing cost is
A radiating board having a step can be manufactured by a very inexpensive method.

The important thermal characteristics of the heat-dissipating substrate are as follows: the plate material of this embodiment has a density of 9.6 g / cm ³ , a coefficient of thermal expansion of 9.1 × 10 ⁻⁶ / ° C., and a thermal conductivity of 237 w / m ·
K was obtained, which met the demands of users.

Thereafter, nickel plating was performed to assemble the component as a component in a ceramic package. There are various types of ceramic packages, but the one that directly contacts the heat dissipation board to the semiconductor chip, the one that is used as a lid (cap), and the lid that is a metal heat dissipation board are based on the difference in thermal expansion. In some cases, semiconductor chips are intentionally joined to achieve design matching such as thermal balance of the entire package.

Here, FIG. 2 shows that a convex portion 4 is formed at the center,
FIG. 3 shows a heat radiating substrate 1 having a step having a form in which a semiconductor chip 5 is mounted on a convex part 4, while FIG. 3 shows a heat radiating substrate having a step having a convex part 4 formed on the periphery as a package lid. 1 is shown. It has been found that these projections can be easily formed by pressing, and all of them can be applied as a heat dissipation substrate having a step.

Next, a second embodiment will be described.

After sufficient mixing with molybdenum powder so that the copper content is 50 wt%, press molding, and then 1200 ° C. × 2
The sheet sintered for a time was subjected to hot rolling and cold rolling to produce a sheet material having a thickness of 1.0 mm.

The outer peripheral rectangular portion in FIG. 4 was processed by a die punching press. In addition, the heat dissipation board 1 having the step shown in FIG.
Is provided with a bent convex portion 7 at the center thereof by bending by pressing or chucking.

The thermal characteristics were as follows: density 9.5 g / cm ³ , coefficient of thermal expansion 11.0 × 10 ⁻⁶ / ° C., thermal conductivity 253 w / m · K
Was obtained, and the evaluation was performed 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 was produced.

In order to mount a semiconductor chip, if a part of the heat sink is made to be a convex part 4 (FIG. 1) or a bonding wire pad is made to be a convex part of 0.1 to 0.15 mm, if integrated pressing can be performed, Although it is possible to contribute to the reduction of the processing cost, when the above-mentioned plate material having a thickness of 1.5 mm is subjected to plastic working by a die press, the thermal substrate 1 having the steps shown in FIGS. 1, 5 and 6 is obtained.

When the volume of the concave portion 8 in FIG. 5 is large, a convex portion is generated at one end of the concave portion 8 in the plate thickness direction. The protrusion cannot be absorbed. At this time,
Since the plate material according to this embodiment has extremely good workability, the projections can be removed by cutting. As described above, since the plate material in this embodiment can be cut, the heat dissipation board 1 having the step can be manufactured at a low cost.

The thermal characteristics of the plate according to the third embodiment are as follows.
4 g / cm ³ , a coefficient of thermal expansion of 12.3 × 10 ⁻⁶ / ° C., and a thermal conductivity of 272 w / m · K were obtained. The evaluation was performed in the same manner as in Example 1, and the usefulness was confirmed.

The hardness and Erichsen value of a composite material obtained by sintering a powder containing 40%, 50%, and 60% of copper in molybdenum as a measure of workability of a heat dissipation substrate having a step are as follows. Is shown in Table 1.

[0032]

[Table 1]

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

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

[0035]

According to the present invention, a package on which a semiconductor element is mounted, particularly a ceramic package which is excellent in reliability, sometimes hinders the ultimate goal of generalization and contributing to the development of industry if mass production cost is high.

According to the present invention, there is provided a heat radiating substrate having a step having an excellent mass productivity and workability, a low cost and a low cost, in which the thermal conductivity is a certain value or more and the coefficient of thermal expansion is within a certain range. A ceramic package to be incorporated can be provided, and the convenience can be significantly improved.

[Brief description of the drawings]

FIG. 1 shows first and third embodiments of the first embodiment of the present invention.
FIGS. 3A and 3B are a front view and a cross-sectional view of a heat dissipation board having a first step in FIG.

FIG. 2 is a cross-sectional view of a heat radiating substrate having a second step on which a semiconductor chip is mounted according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of a heat dissipation board having a third step used as a package lid according to the first embodiment of the present invention.

FIG. 4 is a front view and a cross-sectional view of a heat dissipation board having steps according to a second embodiment of the present invention.

FIG. 5 is a front view and a cross-sectional view of a heat dissipation board having a second step according to a third embodiment of the present invention.

FIG. 6 is a front view and a sectional view of a heat dissipation board having a third step according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat dissipation board with step 4 Convex part 5 Semiconductor chip 7 Bent convex part 8 Concave part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryo Igarashi 2nd Iwase Koshimachi, Toyama City, Toyama Pref. Tokyo Inside Tungsten Co., Ltd. Toyama Works (72) Inventor Yoshihiko Doi 6-40-1, Aoto, Katsushika-ku, Tokyo Tokyo Tungsten Co., Ltd. Tokyo Works (56) References JP-A-5-243436 (JP, A) JP-A-6-13494 (JP, A) JP-A-4-257245 (JP, A) JP-A-4-34862 (JP, A)

Claims (2)

(57) [Claims] 1. A ceramic package used for mounting a semiconductor device, which is formed by mixing, sintering, and rolling copper and molybdenum powders, and forming 200 w / m · m.
A ceramic package having a thermal conductivity of not less than K, a thermal expansion coefficient of 9 to 16 × 10 ⁻⁶ / ° C., and a heat radiating substrate processed into a shape having a step. 2. A heat dissipation board used for a ceramic package, which is formed by mixing, sintering and rolling copper and molybdenum powder, has a thermal conductivity of 200 w / m · K or more, and has a coefficient of thermal expansion. Punching at 9-16 × 10 ^-6 / ° C.
A heat dissipating substrate processed into a stepped shape by one or a combination of two or more of cutting, pressing, stepping, shearing, punching, and bending.