JPH0529508A - Ceramic package - Google Patents

Abstract

PURPOSE:To obtain a highly reliable ceramic package excellent in heat dissipating properties wherein the generation of cracks, exfoliation, etc., caused by difference of thermal expansion between a ceramic package main body and a heat dissipation fin is little. CONSTITUTION:In a ceramic package 1c provided with a ceramic package main body 9a accommodating a semiconductor integrated circuit chip, and heat dissipation fins 7c which are bonded to the package main body 9a, and dissipate the heat generated in the package main body 9a, the base end portion 8a of the heat dissipation fin 7c to be bonded to the ceramic package main body 9a is formed by using the same kind of ceramic material as the ceramic package main body 9a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic package for housing a semiconductor device or the like, and more particularly, to a reliability capable of preventing cracking of the package body and peeling of a joint of the radiation fin due to a difference in thermal expansion between the radiation fin and the package body. Ceramics package with high properties.

[0002]

2. Description of the Related Art Generally, a semiconductor ceramic package is manufactured through the following steps. That is,
On the green sheet, which is a ceramic molded body such as alumina (Al ₂ O ₃ ), a desired circuit pattern or electrode pad,
After printing the bonding pads, etc., and stacking multiple ceramic green sheets with different circuit patterns printed as needed to integrate them, and then firing the integrated work piece into a sintered body, and then outside the sintered body. It is manufactured by plating the surface.

FIG. 3 shows a typical example of a conventional ceramic package 1. In the figure, the upper surface side of the ceramic package 1 is formed flat, while a large number of electrode pads (I / O pads) 2 are formed on the lower surface side, and lead pins 3 are joined to the respective electrode pads 2. A recess 5 for accommodating the semiconductor IC chip 4 and the like is formed in the center of the lower surface of the ceramics package 1. The recess 5 is hermetically sealed by a cap 6 to protect the semiconductor IC chip 4 from moisture and the like. Protects from. Semiconductor IC
Each terminal (lead) of the chip 4 is bonded to a bonding pad (not shown) formed in the package 1 with a wire, and each wiring pattern in the package 1 is drawn out from each lead pin 3 to the outside.

By the way, in recent years, there has been a strong demand for higher speed and higher density mounting of electronic equipment.
High-speed (ECL) ceramic packages of about 100 ns are becoming mainstream. In this high-speed ceramic package, the amount of heat generated is inevitably large, and measures for further improving the heat dissipation characteristics and measures for preventing failures due to thermal expansion are being researched.

For example, as a ceramic material forming the ceramic package 1, conventional alumina (Al ₂
Aluminum nitride (A ₃ ) whose thermal conductivity is several times higher than that of O ₃ ).
1N) or silicon carbide (SiC) to improve the heat transfer characteristics and to bring the thermal expansion coefficients of the semiconductor IC chip 4 and the ceramic package 1 close to each other to reduce mutual interference due to the difference in thermal expansion. Has been done. Further, as shown in FIGS. 4 and 5, heat radiation fins 7a, 7b formed of a highly heat conductive metal material such as aluminum are attached to the upper surfaces of the packages 1a, 1b to increase the heat radiation area. . As a material for the radiation fins 7a and 7b, a metal having a high thermal conductivity, a low cost, easy processing, and a light weight,
For example, copper or the like is used in addition to the above aluminum.

[0006]

However, since the radiation fins are usually made of metal, the difference in the coefficient of thermal expansion from the package material is large, and peeling or thermal stress at the bonding portion between the radiation fins and the package body is large. There is also a problem that the ceramic package is apt to be cracked due to the above, and the reliability of the operation of the electronic device using the package is easily lowered.

As a measure against the above problems, the heat radiation fin itself is formed by a metal material having a coefficient of thermal expansion similar to that of the ceramic package constituent material, for example, a refractory metal material such as tungsten or molybdenum, or a plate shape. The structure of using the high melting point metal material as a thermal stress buffer layer between the package and the radiation fin was also adopted. However, since high-melting-point metal materials such as tungsten and molybdenum have a remarkably small thermal conductivity as compared with aluminum and copper, there is a problem that heat radiation characteristics are significantly deteriorated.

That is, it has a high thermal conductivity exceeding 200 W / m · k and a coefficient of thermal expansion of 4 × 10.
^In the case of using a ceramics package having a value close to ⁻⁶ / ° C. and a semiconductor element, it is difficult to use the conventional metal radiation fin as it is from the viewpoint of the difference in thermal expansion coefficient and the thermal conductivity.

The present invention has been made in order to solve the above-mentioned problems, and there is little occurrence of cracking or peeling due to the difference in thermal expansion between the ceramic package body and the heat radiation fin, and the heat radiation characteristics are excellent and the reliability is high. The purpose is to provide a ceramic package.

[0010]

In order to achieve the above object, a ceramics package according to the present invention is a ceramics package body accommodating a semiconductor integrated circuit chip, and is joined to the ceramics package body to generate in the ceramics package body. A ceramic package having a heat radiation fin for dissipating heat is characterized in that the base end of the heat radiation fin joined to the ceramic package body is formed of the same ceramic material as that of the ceramic package body.

When the heat radiation fin body is made of metal, the heat radiation fin body may be discontinuously arranged on the upper surface of the base end.

Further, as the ceramic material constituting the ceramic package body and the base end portion of the radiation fin, aluminum nitride (AlN), which has a higher thermal conductivity than alumina (Al ₂ O ₃ ) which is a conventional material, and carbonized Silicon (SiC) and beryllia (BeO) are preferably used alone or in admixture of two or more. . According to the above ceramic material, since the thermal conductivity is high, excellent heat dissipation characteristics can be obtained.

Further, it is desirable that the radiating fin main body is formed of a metal material such as aluminum or copper which is inexpensive, has high thermal conductivity, and can be easily processed into a complicated shape. Then, the metal radiation fin body is integrally joined to the surface of the radiation fin base end portion formed of a sintered body of a ceramic material by a brazing method or the like to form a radiation fin. And
The radiation fin thus formed is integrally joined to the surface of the ceramic package body to form the ceramic package according to the present invention.

As the above-mentioned joining method, for example, heating is performed while an active metal brazing material such as Ag-Cu-Ti foil is interposed at the joining interface between the surface of the ceramic package body and the base end of the heat radiation fin, and both are joined. There are an activated metal method of joining by utilizing mutual diffusion movement of constituent metal atoms and Ti atoms of the member, or an adhesive method of adhering the heat radiation fin to the surface of the ceramic package body with a highly heat conductive adhesive such as silicone compound. .

Further, by forming the ceramic package main body and the base end portions of the heat radiation fins from the same type of ceramic material, the difference in thermal expansion amount between the two can be eliminated, and the package cracks due to the difference in thermal expansion. Can be effectively prevented.

Further, when the heat radiation fin main body is made of metal, disposing the heat radiation fin main body discontinuously on the base end surface can further alleviate the effect of thermal expansion. That is, when a metal having a larger coefficient of thermal expansion than that of a ceramic material is continuously arranged over the entire surface of the base end portion, stress due to the difference in thermal expansion acts over the entire length of the base end portion, but the heat dissipation fin main body is not affected. By arranging continuously, the stress is dispersed in each small region in which the discontinuous portion is formed, and the stress acting on the base end of the heat radiation fin is also reduced.

Further, the shape, size, number of arrangements, forming positions, etc. of the heat dissipating fin main body formed in a protruding shape are not particularly defined, and are determined in consideration of factors such as the size, shape, and thermal resistance value of the package main body. . That is, the shape of the heat radiation fin body may be any of a cylinder, a prism, a triangular pyramid, a plate, an amorphous shape, and the formation position may be on the upper surface, the bottom surface, or the side surface of the ceramic package body.

[0018]

According to the ceramic package having the above-described structure, since the base end portion of the radiation fin directly joined to the ceramic package body is made of the same material as that of the ceramic package body, there is no difference in thermal expansion between the two and Less stress is generated. Therefore, the ceramic package body is not cracked or peeled off at the bonding portion between the two, and a highly reliable ceramic package can be obtained.

Further, since the thermal stress generated between the base end portion of the heat radiation fin and the ceramic package body is small, it becomes possible to attach the heat radiation fin to the entire base end portion.
The heat dissipation area is large and the heat dissipation characteristics can be greatly improved.

Further, of the entire radiation fin, only the base end portion is made of ceramics, while the radiation fin main body is made of metal which is easy to process into a complicated shape and is inexpensive, so that the radiation fin as a whole can be manufactured at low cost. Can be manufactured in.

[0021]

An embodiment of the present invention will now be described with reference to the accompanying drawings. 1 and 2 are a plan view and a side sectional view showing Examples 1 and 2 of the ceramic package according to the present invention, respectively.

Ceramic multilayer substrate 1c of Examples 1 and 2
Aluminum nitride (AlN) was used as the ceramic material in each of the materials 1d to 1d, and each was manufactured in the following steps.

That is, a powder containing AlN raw material powder and 3% by weight of yttrium oxide (Y ₂ O ₃ ) as a sintering aid was slurried to obtain a slurry. Next, after molding the obtained slurry into a green sheet (GS) with a thickness of 0.7 mm by a doctor blade method, a large number of blanks are punched out so that one side is 130 mm and a square shape is formed, and a wiring pattern is printed. Wiring parts such as electrode pads and wire bonding pads were printed with a conductive paste mainly composed of tungsten (W).

Then, a plurality of green sheets were integrally laminated by a thermocompression bonding method to form a laminated body having a thickness of 3 mm, the periphery was cut and degreased, and then heated in a N ₂ gas atmosphere at a temperature of 1800 ° C. for 6 hours to be baked. Bonding was performed to obtain a sintered body having a square shape with a side of 42 mm and a thickness of 2 mm. Further, the electrode pad and the wire bonding pad are made to have a thickness of 2 by electrolytic Ni plating.
A μm Ni plating layer was formed. Then, the lead pins 3 are brazed and joined to the electrode pads 2, and then the lead pins are again Ni-plated, and then a gold (Au) plating layer having a thickness of 2 μm is formed to form a PGA (Pin Grid Array) type ceramic package. 1c and 1d were formed. The recessed portions 5 accommodating the semiconductor IC chips 4 are hermetically sealed by the caps 6, respectively.

Next, each ceramic package 1c, 1d
The radiating fins 7c and 7d joined to the surface portion of will be described.

Embodiment 1 as shown in FIGS. 1 (A) and 1 (B)
The heat radiation fins 7c are integrally brazed to the surface of the main body of the ceramic package 1c according to 1 above by soft soldering. The heat radiation fin 7c includes a base end portion 8a directly joined to the ceramic package body 1c and a base end portion 8a.
It is composed of a metal radiating fin main body 9a protruding from the upper surface. The base end portion 8a has a coefficient of thermal expansion of 4 × 10 ⁻⁶ / ° C.,
It is composed of an aluminum nitride substrate having a thermal conductivity of 200 W / m · k. Further, after forming a Ti / Ni / Au layer on the surface of the base end portion 8a by a thin film method, a thickness of about 4
A μm gold plating layer was formed.

On the other hand, the radiation fin body 9a has a diameter of 1.0.
It was formed from an aluminum pin cut to a length of 15 mm from a round bar of mm. The end face of each pin is preliminarily polished, and then a large number of pins are integrally brazed to the upper face of the base end portion 8a on which the gold plating layer is formed using eutectic silver solder of Ag80% / Cu20%. The radiation fin 7c is used.

A radiation fin 7d is integrally joined to the main body surface of the ceramic package 1d according to the second embodiment shown in FIGS. 2A and 2B by soft soldering. This heat radiation fin 7d has a thickness of 1 mm, a height of 15 mm, and a length of 42 mm on the upper surface of a base end portion 8b made of aluminum nitride, which is the same as that of the first embodiment.
A large number of plate-shaped heat radiation fin bodies 9b were formed by brazing and joining.

On the other hand, as Comparative Example 1, as shown in FIG. 3, the same material as in Example 1 was treated under the same conditions except that the surface of the ceramic package body 1 was made flat without forming heat radiation fins. Then, a conventional ceramic package was manufactured.

As Comparative Example 2, as shown in FIG.
A rectangular plate-shaped cooling element is arranged in four stages in the vertical direction,
A conventional ceramic package was manufactured in exactly the same manner as in Example 1 except that the heat radiation fin 7a formed in 1 was directly bonded to the ceramic package 1a using an epoxy adhesive.

As Comparative Example 3, as shown in FIG. 5, a large number of plate-shaped cooling elements are arranged in the horizontal direction, and a radiation fin 7b entirely made of Al is similarly integrally joined to the ceramic package body 1b. To produce a conventional ceramic package.

In order to evaluate the heat dissipation characteristics and reliability of each of the ceramic packages according to Examples 1 and 2 and Comparative Examples 1 to 3 thus obtained, a thermal resistance (R _th ) measurement test was conducted and the thermal resistance (R _th ) was measured. Impact test (TCT) 500
It was carried out cycle by cycle and the rate at which defects such as cracking and peeling occurred for the package was measured.

Here, the thermal resistance measurement test is performed by utilizing the temperature dependence of the forward voltage drop V _BE between the base and the emitter of the transistor incorporated in each ceramic package, and the thermal resistance R _th ( C / W) was adopted.

The thermal shock test was carried out up to 100 cycles, with the operation of holding the temperature at −55 ° C., room temperature (25 ° C.) and 150 ° C. for 10 minutes each as one cycle.

The measurement calculation results are shown in Table 1 below.

[0036]

[Table 1]

As is clear from the results shown in Table 1, according to the ceramics packages of Examples 1 and 2, the base end portions 8a and 8b of the radiation fins 7c and 7d and the ceramics package bodies 1c and 1d are of the same type. Since it is formed of the above ceramic material, cracks and peeling due to the difference in thermal expansion coefficient are less likely to occur, and a highly reliable ceramic package can be obtained. In addition, since the radiating fin main body having a large area can be formed on the entire surfaces of the base end portions 8a and 8b that do not generate thermal stress, the heat radiating characteristic is also excellent. Further, the aluminum nitride substrate forming the base end portions 8a and 8b has a high heat conductivity as high as that of a metal, and thus has good heat dissipation.

On the other hand, in the ceramic package 1 of Comparative Example 1, since the heat radiation fin is not formed, the thermal resistance Rth
In the ceramic packages of Comparative Examples 2 and 3, the metal heat radiation fins 7a and 7b are directly bonded to the ceramic package main bodies 1a and 1b.
The thermal stress becomes large, and cracks are likely to occur.

[0039]

As described above, according to the ceramic package of the present invention, since the base end portion of the radiation fin directly joined to the ceramic package body is made of the same material as that of the ceramic package body, the space between them is reduced. There is no difference in thermal expansion, and thermal stress is less likely to occur. Therefore, cracks in the ceramic package body,
It is possible to obtain a highly reliable ceramic package without peeling or the like at the bonded portion between the both.

[Brief description of drawings]

1A and 1B are respectively a plan view and a side sectional view showing a first embodiment of a ceramic package according to the present invention.

2A and 2B are a plan view and a side sectional view, respectively, showing a second embodiment of the present invention.

FIG. 3 is a side sectional view showing a structural example of a conventional ceramic package.

FIG. 4 is a side cross-sectional view showing a structural example of a conventional ceramics package in which radiating fins entirely made of aluminum are integrally joined.

FIG. 5 is a side cross-sectional view showing another example of the structure of a conventional ceramics package having a radiation fin attached thereto.

[Explanation of symbols]

1, 1a, 1b, 1c, 1d Ceramics package body 2 Electrode pad (I / O pad) 3 Lead pin 4 Semiconductor IC chip 5 Recessed portion 6 Cap 7, 7a, 7b, 7c, 7d Radiating fin 8, 8b Base end portion 9 , 9b Radiating fin body

Claims (3)

[Claims] 1. A ceramics package body having a ceramics package body containing a semiconductor integrated circuit chip, and heat radiation fins joined to the ceramics package body for dissipating heat generated in the ceramics package body. A ceramic package in which the base end of the heat radiation fin joined to the ceramic package is made of the same ceramic material as the ceramic package body. 2. Ceramic materials are aluminum nitride (AlN), silicon carbide (SiC) and beryllia (B).
The ceramics package according to claim 1, wherein the heat radiation fin main body is formed of at least one of aluminum and copper, and the heat radiation fin main body is formed of at least one of eO) and the base end portion is removed. 3. The ceramic package according to claim 1, wherein, when the heat radiation fin body is made of metal, the heat radiation fin body is discontinuously arranged on the upper surface of the base end portion.