JPS6236391B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to a semiconductor device having a brazed portion.

With the development of small electronic circuit devices, especially hybrid integrated circuits and high frequency semiconductor devices, various insulating materials have come to be used. As is well known, due to the recent emphasis on miniaturization of electronic circuits and demands from the electrical characteristics aspect,
There are significant restrictions on the materials used and the physical structure, and there are considerable difficulties in satisfying all of the required properties. An important issue among these is brazing. When brazing metal leads, etc. to a limited area such as an electronic circuit board or container, in order to ensure the specified brazing strength, the characteristics of the constituent materials, metallization technology, and brazing technology must be balanced. However, due to electrical aspects such as high frequency characteristics, it is often impossible to apply solutions that are considered simply from the perspective of brazing technology. For example, the first
As shown in the figure, a metallized layer 2 is formed on the surface of an insulating substrate 1.
When brazing a flat lead 3 to the layer 2, the width of the metallized layer, the width of the lead, and the amount of brazing material 4 must be selected appropriately in order to obtain the required brazing strength. Must be. For example, when manufacturing an electronic circuit board that uses beryllia ceramic, which has a low dielectric constant and good heat dissipation, as the insulating substrate 1 and has a desired characteristic impedance, it is necessary to give priority to electrical characteristics, so the metallized layer is It is often difficult to obtain the specified metallization strength and brazing strength due to limitations on width and lead width. The effect is particularly noticeable in electronic circuits used in high frequency ranges. To solve this problem, various methods have been proposed up to now, as shown in FIG. The strain can be alleviated by allowing the brazing material 4 to accumulate in the brazing part, or by providing a metallized layer 2'' on a part of the side surface of the insulating substrate 1 as shown in FIG. There is a method of increasing the brazing strength by increasing the brazing strength.Other methods have also been proposed, such as providing a hole in the brazing part of the external lead 3 or creating a shape as shown in FIG. 4 to make it easier for the brazing material 4 to accumulate. However, in the case of FIG. 2, the brazing material 4 substantially flows to other parts of the external lead 3, making it difficult to create a wax reservoir with a good yield. In this case, there is a drawback that the substantial capacitance between the side metallized layer 2'' and the back metallized layer 2' of the insulating substrate 1 increases, thereby impairing the electrical characteristics. Furthermore, even if the shape of the external lead is modified, the wax yield will only improve to some extent, but no essential solution will be obtained.

On the other hand, when considering the assembly of electronic circuits, brazing filler metal may leak out and cause various problems at the locations where electronic circuit elements are mounted or where bonding is performed with thin metal wires, etc. For example, mounting or bonding may not be possible, or mounting may not be possible. Even if bonding is possible, it increases the thermal resistance, increases the stray capacitance of the connection, or even if bonding is possible, the bonding strength is weak.
There are drawbacks such as the bonding strength decreasing during long-term life tests.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional technology, and therefore, an object of the present invention is to solve the problem of deteriorating the electrical and mechanical characteristics of a semiconductor device in which a semiconductor element is brazed onto a metal body. without any
An object of the present invention is to provide a novel semiconductor device that can easily ensure a predetermined brazing strength.

According to the present invention, in a semiconductor device in which a semiconductor element and a wall member enclosing the semiconductor element are brazed onto a metal body, the surface of the metal body in the portion where the wall member and the semiconductor element are brazed is made of a metal that is easily wetted by the brazing material. A semiconductor device is obtained in which a member is provided and a metal that is difficult to wet with a brazing material is interposed between a semiconductor element and a wall member.

In this way, the brazing technology of the present invention provides the brazing part with a metal layer that is easily wettable (easily compatible) with the brazing material, and at least the portions that are close to the brazing material are provided in areas where the brazing material should not flow out. This is a technique that makes the brazing material a metal that is difficult to wet (hard to get acquainted with). That is, by consecutively arranging a metal layer that is easily wetted by the brazing material and a metal that is difficult to wet the brazing material in the brazing part, a brazing pool can be easily formed, and at the same time, the above-mentioned problem caused by the outflow of the brazing material that occurs in the conventional technology can be avoided. This prevents various troubles such as:

If a metal that is difficult to wet with the brazing material is used as the metal body, the part to be brazed will be coated with a metal that is easy to get wet with the brazing material, exposing the bare surface of the metal body that is difficult to get wet with the brazing material, and preventing the soldering material from flowing out. It can act as a blocking part.

Next, in order to clarify the present invention more specifically, an explanation will be given based on an embodiment with reference to FIGS. 5 and 6.

FIG. 5 is a diagram for explaining one embodiment of the present invention, in which a stud (heat sink) 16 (for example, copper) is used.
An insulating wall member 17 (for example, alumina) based on the usual laminated ceramic technology (the insulating member 17 includes a metallized layer 18 to become an electrode of the container and a metallized layer 18' to be brazed to the stud 16).
A container is formed by brazing the external drawer lead 13 and a semiconductor element 19 (for example, a transistor) is mounted inside the container, and is connected by thin metal wires (for example, gold wire) 20, 20'. In a semiconductor device, for example, an FET, in which the electrodes of the semiconductor element 19 and the semiconductor container are electrically connected, the studs 16 and the insulating wall member 17 are connected with the brazing material 1.
4 (for example, silver-copper eutectic solder), a metal layer 15 (for example, Ni) that easily wets the brazing material 14 is applied only to the brazed portion of the stud 16 by plating, etc., and then the metal layer 15 is A part of the stud 16 is removed to expose the metal layer that is difficult to wet with the brazing material, that is, a groove 21 is provided by cutting or the like, or a protrusion 22 is provided on the stud 16 as shown in FIG.
The metal layer 15 which is easily wetted by the brazing material 14 may be covered by shielding and closing it in some way, that is, the metal layer 15 which is easily wetted by the brazing material 14 may be formed as a metal layer which is difficult to get wetted by the brazing material 14. If these grooves 21 or protrusions 22 are formed, the distance between the mounting part of the semiconductor element and the bonding part of the thin metal wire will be considerably longer from the brazing part, so the reliability of the mounting part and the bonding part will further increase. .
In order to prevent the wax from flowing, methods such as applying a wax flow preventive agent or partially providing a glass or oxidized layer may be considered; however, applying a wax flow preventive agent,
Removal requires advanced technology, and installation of glass or oxide layers causes material deterioration due to cycles of oxidizing and reducing atmospheres, and installation and removal of such layers requires advanced technology. Both techniques cannot be said to be desirable methods because they require a significant amount of man-hours.

According to the present invention, there is provided a brazing method that can extremely easily ensure a predetermined brazing strength without deteriorating the mechanical and electrical properties of the object to be brazed and its adjacent members. given,
All of the conventional drawbacks mentioned above are completely eliminated.

Although the present invention has been described above with respect to its preferred embodiments, it goes without saying that these are merely illustrative and do not have a limiting meaning. Accordingly, the present invention may be practiced with various modifications without departing from the spirit and scope of the invention, but all such modifications are included within the scope of the claims of the present invention.

[Brief explanation of the drawing]

Figure 1 is a basic diagram of brazing technology, Figures 2 to 4 are diagrams for explaining conventional brazing technology, and Figure 5 is a basic diagram of brazing technology.
The figures and FIG. 6 are cross-sectional views for explaining each embodiment according to the present invention. 1... Insulating substrate, 2, 12... Metallized layer,
3, 13... External drawer lead, 4, 14... Brazing metal, 5, 15... Metal layer to which the brazing metal is easily wetted, 16
... Stud, 17 ... Insulating wall member, 18 ... Metallized layer, 19 ... Semiconductor element, 20 ... Fine metal wire, 21 ... Groove, 22 ... Projection.

Claims (1)

[Claims] 1. In a semiconductor device in which a semiconductor element and a wall member enclosing the semiconductor element are brazed onto a metal body, a metal member that is easily wetted by a brazing material is provided on the surface of the metal body in a portion where the wall member and the semiconductor element are brazed. A semiconductor device characterized in that a metal that is difficult to wet with the brazing material is interposed between the semiconductor element and the wall member.