JPS6236392B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to a semiconductor device that requires brazing technology.

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, the recent emphasis on miniaturization of semiconductor devices and the demands for electrical characteristics have placed significant restrictions on the materials and physical structures used, making it extremely difficult to satisfy all of the required characteristics. There is a problem. An important issue among these is brazing. When brazing device components onto a limited area such as a substrate or container for mounting semiconductor elements, it is necessary to balance the properties of the constituent materials, metallization technology, and brazing technology in order to ensure the desired brazing strength. However, it is often not possible to achieve this harmony only from the electrical aspects such as high frequency characteristics or simply from the aspect of brazing technology. For example, when a metallized layer 2 is applied to the surface of an insulating substrate 1 as shown in FIG. 1, and a flat lead 3 is brazed to the layer 2, the width of the metallized layer must be , the width of the leads, and the amount of brazing filler metal 4 must be selected appropriately. 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. ing.

However, in the case of Fig. 2, the brazing material 4
Since the wax flows to other parts of the external lead 3, it is difficult to form a wax reservoir with a good yield, and the connection strength is also weak. Further, in the case of the structure as shown in FIG. 3, 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, impairing the electrical characteristics. Even if the shape of the lead, that is, the brazing body is modified, the solder retention rate will only improve somewhat, but no essential solution will be obtained.

On the other hand, when considering the assembly of electronic circuits, various problems may occur at the locations where electronic circuit elements are mounted or bonded with fine metal wires due to the leakage of the brazing material, for example, the diffusion of the brazing material makes mounting or bonding impossible. Alternatively, even if mounting is possible, there are disadvantages such as increasing thermal resistance, increasing connection stray capacitance, or even if bonding is possible, bonding strength is weak, and bonding strength decreases in long-term life tests. In particular, in a container structure for enclosing a semiconductor element, brazing the enclosing wall member has many drawbacks and is difficult.

An object of the present invention is to provide a semiconductor device having a structure in which the brazing strength of a wall member can be easily ensured without deteriorating the electrical and mechanical properties of the object to be brazed and other electrical and mechanical properties.

The above object of the present invention is to selectively provide a metal member that is easily wetted by a brazing material on the surface of a metal plate to which a wall member is connected, at a portion where the wall member abuts, and to connect this metal member and the wall member. This is achieved by a semiconductor device characterized by being soldered.

In this way, in the semiconductor device of the present invention, the brazing part is limited by the metal member to which the brazing material easily wets (fits easily), so that the brazing material accumulates only in that part,
Furthermore, the periphery of the metal layer acts as a boundary to stop the outflow of the brazing material, so that the brazing material does not spread onto the metal plate adjacent to the metal layer.

In other words, instead of simply brazing to a metal plate, a metal layer that is easily wetted by the brazing material is provided to prevent the brazing material from flowing to areas other than those to be brazed, and to prevent the brazing material from spreading toward the metal plate. This is to prevent the various troubles mentioned above due to the leakage of the brazing filler metal that occurs in this technique.

In other words, the present invention uses a metal body to which the brazing material does not easily wet as the metal plate, and by covering the portion where the brazing material is to be coated with a metal member to which the brazing material easily wets, the surface of the metal body, especially the brazing material, is This wall member mounting structure is characterized in that the brazing filler metal contracts toward the metal member at the boundary with the easily wetted metal member, thereby acting as a blocking portion against outflow of the brazing filler metal.

Next, in order to clarify the gist of the present invention more specifically, an explanation will be given based on embodiments with reference to the drawings.

FIG. 5 is a sectional view for explaining one embodiment of the semiconductor device according to the present invention.

As shown in FIG. 5, a stud (heat sink) 16
(for example, copper with good heat dissipation) and an insulating wall member 17 (for example, alumina) based on ordinary laminated ceramic technology (the insulating member 17 includes a metallized layer 18 that will become the electrode of the container and a layer for brazing to the stud 16). metallized layer 18' is provided)
A container is formed by brazing the external lead 13 on the upper side of this wall member, and a semiconductor element 19 (for example, a transistor) is mounted inside the container, and thin metal wires (for example, gold wire) 20, 20 are mounted. In a semiconductor device, such as an FET, in which the electrode of the semiconductor element 19 and the semiconductor container are electrically connected through ) when brazing,
If only the brazed portion of the stud 16 is selectively covered with a metal layer 15 (for example, Ni) that is easily wetted by the brazing filler metal 14, the brazing filler metal 14 will not flow into the container, and the mounting portion of the semiconductor element 19 and The reliability of the bonding portion of the thin metal wire 20' is significantly increased.

In this embodiment, a metal layer 15 to which the brazing filler metal 14 easily wets is selectively provided on the stud 16 at a location where the bottom surface of the wall member comes into contact, but this is only the metal layer 15. The purpose is to improve the connection strength with the wall member 17 by making the brazing filler metal rise up in a concentrated manner. In order to prevent the flow of the solder metal, methods such as applying a solder flow prevention agent or partially providing a glass or oxidized layer may also be considered.
Highly sophisticated techniques are required to apply and remove the wax flow preventive agent, and the installation of glass or oxide layers induces material deterioration due to the cycle of oxidizing and reducing atmospheres.
Furthermore, this method cannot be said to be a desirable method because a high level of skill is required to install and remove the layer, and both techniques require a significant number of man-hours.

However, according to the present invention, a brazing method is provided 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. This eliminates all of the conventional drawbacks mentioned above.

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,
All of these are intended to be included within the scope of the claims set forth above.

[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 figure is a sectional view of an embodiment of a semiconductor device using a brazing structure 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 ... Metal thin wire.

Claims (1)

[Claims] 1. In a semiconductor device that encapsulates a semiconductor element mounted on a metal body and has a wall member, a metal member that is easily wetted by a brazing material is selectively provided on the surface of the metal body opposite to the bottom surface of the wall member, and that part A semiconductor device characterized in that a wall member is brazed with.