JPH08236657A - Ceramic package and manufacture thereof - Google Patents

Abstract

PURPOSE: To mount a ceramic package surely and reliably on a board by relaxing thermal stress with respect to the package body at the time of mounting. CONSTITUTION: A part for forming a land pattern 24 is recessed and a laminate 20 of ceramic green sheet, provided with a land pattern 24 to be connected electrically with an inner wiring pattern 22, is formed on the inner bottom face of the recess. After firing the laminate 20, the recess 26 is filled with a brazing maternal 32 which us then bonded with an external connection terminal 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate and a package (hereinafter referred to as a ceramic package) made of ceramics for mounting semiconductor elements and the like, and more particularly to a mounting surface formed on a flat surface. The present invention relates to a ceramic package that can alleviate thermal stress caused by a difference in thermal expansion from a mounting substrate on which a ceramic package is mounted and improve the reliability of bonding with the mounting substrate, and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 4 shows a surface mount type ceramic BGA.
(Ball Grid Array) The general manufacturing method of a package is shown. Ceramic BGA package is a predetermined tungsten
After stacking multiple ceramic green sheets (Fig. 4 (a)) with a metallized pattern made of (W) or molybdenum (Mo), and firing them (Fig. 4 (b)), the package body 1
It is obtained by joining the solder ball 14 to the land pattern 12 formed on the mounting surface side of No. 0. Figure 4 (d) shows Ceramic B
The semiconductor device 15 is mounted on the GA package and the cap 16
The semiconductor device in which the opening of the storage recess of the semiconductor element 15 is hermetically sealed is mounted on the mounting board 17.

By the way, when a laminated body of ceramic green sheets is fired as shown in FIG.
A warp of about 00 μm occurs. The warp of the package body 10 caused by such firing is more prominent in a large package, and a product such as a ceramic BGA package that requires a high degree of flatness on the mounting surface requires some correction in a large product. . Package body 10
As a method of eliminating the warp, the mounting surface side of the package body is conventionally polished to be a flat surface. When making a flat surface by polishing, a land pattern is provided on the polished surface by a method such as thin film formation, sputtering or vapor deposition, or a metallized pattern such as copper having a melting point lower than the firing temperature of the ceramic green sheet is formed by screen printing or the like. A method such as low temperature firing to form a land pattern is used.

[0004]

However, in the case of the method of forming the land pattern by thin film formation after polishing the package body, a processing step for that is required to be newly performed, which causes a problem of high manufacturing cost. is there. Further, in the case of a method of providing a metallized pattern by screen printing or the like, after firing the ceramic green sheet, it is difficult for the solution mixed in the metallized paste to permeate into the substrate so that the pattern easily bleeds to form a fine conductor pattern. There was a problem that it was difficult.

Further, when the conventional ceramic BGA package is mounted on the mounting board, there is a problem that cracks are generated at the joint portion of the solder balls due to thermal stress due to the difference in thermal expansion coefficient between the mounting board and the package body.
Therefore, the present invention has been made to solve these problems, and an object of the present invention is to reliably mount on a mounting board and to effectively reduce stress caused by a difference in thermal expansion between the mounting board and the package body. The present invention aims to provide a ceramic package and a method for manufacturing the same that can be relaxed and highly reliable.

[0006]

The present invention has the following constitution in order to achieve the above object. That is, the mounting surface of the package body is provided with a recess having an inner bottom surface on which a land pattern electrically connected to the external connection terminal is formed, and the recess is filled with a brazing material. Also,
The brazing material is preferably silver brazing, copper or eutectic solder. Moreover, a solder ball can be preferably used as the external connection terminal. Further, the mounting surface of the package body is polished to form a flat surface.

Further, in the method of manufacturing a ceramic package, a portion for joining the external connection terminal is formed in a concave shape, and a land pattern for electrically connecting to the internal wiring pattern is provided on the inner bottom surface of the concave portion formed in the concave shape. A ceramic green sheet laminate is formed, the laminate is fired, a brazing material is filled in the recess, and an external connection terminal is joined to the brazing material. Also,
After the brazing material is filled in the recess, the mounting surface of the package body is polished to form a flat surface.

[0008]

In the ceramic package according to the present invention, the solder material is filled in the recess provided in the package body, and the external connection terminals are joined to the solder material. The thermal stress generated between the package body and the mounting board when the ceramic package is mounted on the mounting board is relieved by the buffering action of the brazing material, so that the ceramic package can be mounted with high reliability.
Further, according to the method for manufacturing a ceramic package of the present invention, a joint portion such as a land pattern for joining the external connection terminal can be easily formed, and the mounting surface of the pattern body can be easily formed to be a flat surface.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a structure of a ceramic package according to the present invention and an embodiment of a manufacturing method thereof. In this embodiment, first, as shown in FIG. 1A, a plurality of ceramic green sheets such as aluminum oxide and aluminum nitride are laminated to form a ceramic green sheet laminate 20. The internal wiring pattern 22 is formed by providing a metallized pattern of tungsten or the like on a ceramic green sheet by screen printing or the like. Reference numeral 24 is a land pattern electrically connected to the internal wiring pattern 22.
Similarly to the case of forming the internal wiring pattern 22, the land pattern 24 can also be formed by providing a metallized pattern by screen printing or the like.

Reference numeral 26 is a recess formed at the position where each land pattern 24 is formed. The concave portion 26 is formed by stacking a ceramic green sheet having through holes corresponding to the formation positions of the land patterns 24 on the ceramic green sheet having the land patterns 24 and the internal wiring patterns 22. As shown in FIG. 1 (a), the laminated body 20 of the ceramic green sheets of the embodiment has a recessed portion where the land pattern 24 is formed, and the land pattern 24 is exposed on the inner bottom surface of the recessed portion 26. 27
Is a storage recess for mounting a semiconductor element, and 28 is a connection pattern electrically connected to the semiconductor element by wire bonding or the like.

Next, the ceramic green sheet laminate 20 is fired under normal firing conditions. FIG. 1B shows the package body 30 after firing. A state in which the package body 30 is warped by firing is shown. Next, the brazing filler metal 32 is put into each recess 26 (FIG. 1 (c)) and heated to melt the brazing filler metal 32. As a result, the brazing material 3 is placed in the recess 26.
2 is filled. The brazing material 32 has the purpose of electrically connecting the external connection terminal such as a solder ball to the land pattern 24, and the purpose of relaxing the thermal stress caused by the difference in thermal expansion coefficient between the package body 30 and the mounting substrate. Brazing material 32
As the material, silver solder, copper, eutectic solder, etc. are useful for the purpose of relaxing the thermal stress.

After the brazing material 32 is filled in the recess 26, the mounting surface side of the package body 30 is polished to make it flat so as to eliminate the warp of the package body 30 (FIG. 1 (d)).
In this polishing operation, the package body 30 and the recess 26
The brazing filler metal 32 filled in is also polished to make the entire mounting surface flat. Therefore, it is necessary to set the recess 26 to a depth such that the brazing material 32 remains in the recess 26 and the land pattern 24 is not exposed even by this polishing operation.

After the mounting surface side of the package body 30 is polished in this manner, external connection terminals are joined to the brazing material 32 to obtain a ceramic package. In the embodiment, solder balls 34 are used as external connection terminals. Solder ball 3
4 is bonded to the brazing material 32 and electrically connected to the semiconductor element 36 via the land pattern 24, the internal wiring pattern 22, and the connection pattern 28. The brazing material 32 is the solder ball 3
Solder balls 3 do not melt at the heating temperature when joining 4
Use one that does not hinder the joining of item 4. In this way, a ceramic package is obtained in which the mounting surface is polished and formed into a flat surface, and the solder balls 34 as external connection terminals are joined via the brazing material 32 (FIG. 1 (e)).

FIG. 2 shows a state in which a semiconductor device in which the semiconductor element 36 is mounted on the ceramic package is mounted on the mounting substrate 40. In the embodiment, the semiconductor element 36 and the connection pattern 28 are connected by a bonding wire, and the cap 38 is hermetically sealed by the seal ring provided on the opening edge of the storage recess 27 to seal the semiconductor element 36. Since the ceramic package of the embodiment has a flat mounting surface, it can be reliably mounted on the mounting substrate 40 via the solder balls 34.

FIG. 3 is an enlarged view showing a joint portion between the mounting substrate 40 and the ceramic package. Mounting board 4 as shown
0 and the ceramic package are joined via the solder balls 34, but the solder balls 34 and the land patterns 2
By interposing the brazing material 32 in the middle of the brazing material 4,
2 acts to relieve the thermal stress generated between the mounting substrate 40 and the package body 30. As described above, by using the ceramic package of this embodiment, an excessive force acts on the joint portion of the solder ball 34 and the package body 3
It is possible to solve the problem that cracks occur at 0.

Further, in the above manufacturing method, the mounting surface of the ceramic green sheet laminate 20 is fired to polish the mounting surface side of the package body 30 in which warpage has occurred to form a flat mounting surface. In the example method, the mounting portion side of the package body 30 is polished to form a connecting portion made of the brazing material 32 for joining the terminals for external connection, and a thin film is formed after the mounting surface side of the package body is polished as in the conventional method. It is not necessary to form a land pattern by a method or the like, the work is easy and the manufacturing cost can be reduced.

When the warp of the package body 30 due to firing does not adversely affect the mounting, the polishing of the package body 30 is omitted, and after filling the brazing material 32,
The external connection terminal may be directly joined to the brazing material 32. Further, the external connection terminal is not limited to the solder ball 34 as in the embodiment, but a lead pin or the like can be used. In the above-mentioned embodiment, the ceramic BGA package accommodating the semiconductor element has been described, but the configuration of the present application can be applied to a substrate for MCM (multi-chip module) in which a plurality of semiconductor elements are mounted on one ceramic substrate. . Since the ceramic package according to the present invention can easily form the mounting surface on the flat surface as described above and can alleviate the thermal stress and the like generated between the mounting surface and the mounting substrate during mounting, it can be mounted on the mounting surface like a large ceramic BGA package. Therefore, it can be suitably applied to a product requiring a high degree of flatness or a product in which thermal stress with a mounting substrate poses a problem.

[0018]

The ceramic package according to the present invention is
As described above, the mounting can be reliably performed on the mounting substrate, and the thermal stress generated between the mounting substrate and the package body is effectively avoided, and highly reliable mounting is enabled. Further, according to the method for manufacturing a ceramic package of the present invention, the above-mentioned ceramic package can be easily manufactured at a low cost, and so on.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a configuration of a ceramic package and a method of manufacturing the ceramic package.

FIG. 2 is a cross-sectional view of a semiconductor device in which a semiconductor chip is mounted on a ceramic package mounted on a mounting board.

FIG. 3 is an explanatory view showing an enlarged joint portion between a package body and a mounting substrate.

FIG. 4 is an explanatory view showing a conventional method of manufacturing a ceramic package.

[Explanation of symbols]

 10 Package Main Body 12 Land 14 Solder Ball 20 Green Sheet Laminate 22 Internal Wiring Pattern 24 Land Pattern 26 Recess 27 Storage Recess 28 Connection Pattern 30 Package Main Body 32 Brazing Material 34 Solder Ball 36 Semiconductor Chip 38 Cap 40 Mounting Board

Claims (6)

[Claims] 1. A package body is provided with a recess having an inner bottom surface on which a land pattern electrically connected to an external connection terminal is formed, and the recess is filled with a brazing material. And ceramic package. 2. The ceramic package according to claim 1, wherein the brazing material is silver solder, copper or eutectic solder. 3. The ceramic package according to claim 1, wherein solder balls are joined as terminals for external connection. 4. The ceramic package according to claim 1, wherein the mounting surface of the package body is polished to form a flat surface. 5. A laminated body of ceramic green sheets, wherein a portion for joining an external connection terminal is formed in a concave shape, and a land pattern electrically connected to an internal wiring pattern is provided on an inner bottom surface of the concave portion formed in the concave shape. Is formed, and after firing the laminated body, a brazing material is filled in the recess, and an external connection terminal is joined to the brazing material. 6. The method of manufacturing a ceramic package according to claim 5, wherein the mounting surface of the package body is polished to form a flat surface after the brazing material is filled in the recess.