JPS6288349A - Resistance welding method for metal frame for semiconductor device - Google Patents

Abstract

PURPOSE:To obtain continuous excellent bonding of non-plated copper frames, by providing many minute holes in regions to be bonded in the metal frames, laminating the frames, increasing the contact resistance between both frames in the regions to be bonded, and carrying out resistance welding. CONSTITUTION:Many holes 12, 12... having a small diameter are provided in a region to be bonded in a non-plated copper frame 11, which is compressed and conducted between a pair of welding electrodes 102a and 102b. Each hole is smaller than the contact surface of the welding electrode. An interval D between the holes is made equal to the thickness of the frame or made larger than the thickness by about 0.1mm. When metal fames are laminated and resistance welding is carried out, the copper frames 11 and 21 are laminated between the pair of the welding electrodes 102a and 102b. The frames are compressed with the electrodes and a current is conducted. At this time, the contact resistance of current conduction in both frames is smaller than a conventional example. Therefore heating is large, and continuous, excellent welding can be accomplished.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a resistance welding method for joining metal frames used in the assembly of semiconductor devices, and is particularly applicable to the assembly of semiconductor devices assembled using metal frames. 6 [Technical Background of the Invention] Metal frames (hereinafter referred to as frames) used for assembling semiconductor devices are often made of iron-based or copper-based materials, and one main surface of such frames is Gluing semiconductor chips (
die bonding) is generally employed.

Furthermore, a plurality of die-bonded frames as described above are joined and assembled by facing each other or stacking them one on top of the other. As a method for joining frames together in this manner, a resistance welding method that can be operated continuously has been used conventionally.

In FIG. 3 illustrating the above, 101 and 111 are frames, which are overlapped to form a pair of welding electrodes 102a,
Welding is achieved by inserting the electrode between the electrodes 102b and 102b, pressing them together with the pair of electrodes, and applying electricity.

[Problems with background technology]

When joining frames using the conventional resistance welding method described above, it is possible to weld frames made of frame materials with high electrical resistance, such as iron frames, without any problems, but welding is possible without any problems when the frames are made of frame materials with high electrical resistance, such as steel frames. 99%), it is possible to weld several frames, but it is not possible to continuously weld more frames than this. The reason for this is that the electrical resistance of copper is low, and the contact resistance between the frames is not much different from the contact resistance between the frames and the welding electrode, so when welding occurs at the contact surface between the frames, the contact resistance between the frame and the welding electrode is also equivalent. This is because heat generation occurs, and the welding electrode or frame melts too much and ends up being joined to each other. This makes it impossible to continue welding.

For example, even if a high melting point metal such as tungsten is used for the welding electrode to avoid electrode welding, the welding state will be unstable with respect to a copper frame. This is because tungsten has a large electrical resistance, and the heat generated at the contact surface between the frame and the electrode relative to the welding current is greater than the heat generated at the contact surface between the frames.

In addition, if the main surface of the frame to which die bonding is applied is pre-plated with gold or silver to improve the die bonding properties of semiconductor chips, the non-plated surfaces should be brought into contact with each other, and each plated surface should be welded. If the welding electrode is brought into contact with the welding electrode, the contact resistance between the frames will be greater than the contact resistance between the frame (plated surface) and the welding electrode, and this can be achieved satisfactorily. However, as recent metal frames have become mainstream without precious metal plating in order to reduce costs, there is a strong demand for a method that can perform good resistance welding on copper frames.

[Purpose of the invention]

In view of the above-mentioned conventional problems, the present invention provides a method of resistance welding a metal frame for a semiconductor device, which can achieve continuous and good bonding to a non-plated copper frame.

[Summary of the invention]

The method of resistance welding metal frames for semiconductor devices according to the present invention includes forming a large number of minute holes in the planned joining area of the metal frames and stacking them, and performing resistance welding by increasing the contact resistance between both frames in the joining area. It is characterized by It also enables resistance welding, especially for copper-based metal frames.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In addition, in the description, parts that are the same as in the prior art are indicated by the same reference numerals as in the prior art in the drawings, and the description thereof will be omitted.

-3=shown in FIG. 2a] is a non-plated copper frame, and a micro-diameter opening 1. 2.12・
There are many... Each of these openings is smaller than the contact surface of the welding electrode, and the interval between the openings is equal to the plate thickness of the frame, but is approximately 0.1 mm larger. In addition, the arrangement of the holes may not be arranged in a row, but may be arranged in a staggered manner, and the shape of the holes is not limited to circular, but may be triangular (Fig. b), oval (Fig. C), or polygonal as shown in Fig. An example of a rectangular shape may be a rectangle (Fig. d), or any other shape may be selected.

Generally, metal frames used for semiconductor devices have a thickness of 0.
It is formed by press punching or etching a copper plate or copper strip of 25 to 0.40 m/m, and the above-mentioned openings are formed at the same time during each processing. Therefore,
When resistance welding is performed by stacking metal frames, as shown in Figure 1, a copper frame 1.1.21 is stacked and inserted between a pair of welding electrodes 102a and 1.02b, and the electrodes are used to perform pressure welding. Then turn on the power. At this time, since the current contact resistance of both frames is smaller than that of the conventional example, heat generation is large and continuous, and good welding is achieved.

〔Effect of the invention〕

According to this invention, since the contact area of the frames is reduced by providing an opening in a part of the joint of the metal frame, the contact area of the frames becomes small, the welding current is concentrated, and heat is generated at the contact surface of the frames. It becomes thicker and exceeds the heat generated by the welding electrode and frame. This has the distinct advantage that good resistance welding can be achieved continuously.

Further, since the present invention can be formed during the conventional processes such as pressing and etching that are applied to the metal frame in manufacturing the metal frame, there is an advantage that the manufacturing process is not extended.

Note that the method of the present invention is not limited to the embodiments, and can also be used to avoid fusion between the welding electrode and the frame when joining metal frames made of different materials, or when joining leads made of metals other than copper. There is also the advantage that good resistance welding can be achieved by

[Brief explanation of drawings]

Figure 1 is a partial cross-sectional perspective view showing resistance welding to explain an embodiment of the present invention, Figures 2a and d are front views showing openings in a metal frame, and Figure 3 is resistance welding. FIG. 2 is a perspective view for explaining a conventional example.

Claims (1)

[Claims] A plurality of holes narrower than the welding electrode pressure area are prepared adjacent to each other in advance in the area to be bonded in the metal frame for semiconductor devices, and after the respective areas to be bonded are overlapped and inserted between the welding electrodes, the welding electrode is energized for pressure welding. 1. A method for resistance welding a metal frame for a semiconductor device, the method comprising welding a metal frame for a semiconductor device.