JPS6297356A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To make sealing performance excellent, by providing the thickness of a cold welded part of two copper plates to be welded within a specified range, forming an Ni plated layer having a specified thickness on the welded surface, and specifying the expression of relation so that a welding deformation rate, thickness of Ni plated layer and thickness of copper plates satisfy the expression. CONSTITUTION:The thickness tCu of each of copper plates of upper and lower metal plates to be welded 3 and 4 is 400mum. An Ni plated layer 13 is formed on the respective welded surfaces so that a plating thickness TNi is 13mum. Then upper and lower assemblies 22 and 23 undergo heat treatment in a hydrogen atmosphere. A mutually diffused layer 14 is formed at the interface between the copper plates and the Ni plated layer. Thereafter, a semiconductor pellet and the like are enclosed between the upper and lower assemblies 22 and 23. The parts from the outer edges to the inner ring parts of two metal plates to be welded undergo cold weld. At this time, a deformation rate R of the metal plate to be welded is 10-85%. Pressure is applied at R=65% so as to satisfy R>=115+2.25tNi-0.21tCu. Thus the device having sealing property can be sealed by cold pressure welding, and working efficiency is improved.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a semiconductor device sealed by cold welding and a method for manufacturing the same. It is used in a certain flat power semiconductor device and its manufacturing method.

[Technical Background of the Invention] From the standpoint of reliability, semiconductor devices usually require an inert gas such as N2 gas to be sealed inside the device to isolate it from the outside air, and therefore the envelope has a sealed structure. Conventionally, 11g welding (arc welding) is generally used as a hermetic sealing technique for semiconductor devices, particularly flat power semiconductor devices. However, in recent years there has been a trend toward sealing this by cold pressure welding technology, and this has already begun to be actually applied to some products of flat power semiconductor devices. The cold pressure welding method is a method in which a large pressure is applied between the members to be welded to join them at room temperature without applying heat from the outside.

A conventional example of a flat power semiconductor device sealed by cold pressure welding will be described based on the drawings.

FIG. 3 is a side view of this device, showing only the Δ-A line cross section (see FIG. 4) near the outer periphery of the metal plate to be welded under pressure.

FIG. 4 is a plan view of FIG. 3.

1 and 5 are electrodes of a flat semiconductor device 21 (for example, a diode). Reference numeral 2 denotes an envelope portion made of an insulating material such as ceramic, which insulates the electrodes 1 and 5 and houses a semiconductor chip (not shown) inside.

Reference numeral 3 denotes an upper pressure-welded metal plate, and 4 denotes a lower pressure-welded metal plate, which is generally a copper plate. The upper pressure-welded metal plate 3 is fixed to the insulating envelope portion 2, and the lower pressure-welded metal plate 4 is fixed to the electrode 5. The two press-welded metal plates 3 and 4 are stacked one on top of the other, and the inner annular portion 6 spaced a predetermined distance l from the outer periphery is cold-welded and hermetically sealed.
FIG. 5 is a side view including a partial sectional view for explaining this sealing step. The two pressure-welded metal plates 3 and 4 are sandwiched between an upper pressure-welding die 7 and a lower pressure-welding die 8, and are pressed and sealed together at room temperature by a pressure applying device such as a press. 6 and 7 are III main views showing the main parts of the upper pressure welding die 7. FIG. 6 is a sectional view taken along the line B-B (see FIG. 7), and FIG. 7 is a plan view thereof. The main part of the lower pressure welding die 8 is generally the same shape as the upper pressure welding die 7. 9
is a press-fitting part of the press-welding die 7, and the shape of the press-fitting part 9 is usually an annular shape with a trapezoidal cross section. Reference numerals 10, 11 and 12 are the tip pressing surface, the outer pressing surface, and the inner pressing surface of the press-fitting part 9, respectively.

By cold welding, the annular portion 6 of the metal plate 3.4 to be welded is pressurized and undergoes plastic deformation. It is thought that the joining between the metal plates to be welded in the cold pressure welding technique is due to the metal atoms of the two metal plates forming a partial metal bond with each other during the process of plastic deformation. The use of cold pressure welding technology for sealing flat power semiconductor devices is recent, and currently copper plates are mainly used as the metal plates to be pressure welded. In some cases, this copper plate is used after being plated with Ni, but in any case, no heat treatment is performed.

[Problems with back m technology] In sealing a flat power semiconductor device, the press-fit sealing portion covers a wide annular area.

With conventional cold welding techniques, it is difficult to obtain a perfect metal bond over this entire area, and micropores often occur in part or the entire surface of the annular pressure welding part. The sealing performance of the pressure welded parts is determined by injecting helium gas into the inside of the envelope, and checking for leakage of helium gas leaking from the pressure welded parts to the outside.
It is measured in tOl-cc/sec). In the case of 11g welding, the standard leakage amount is, for example, 10''' atom
-cc/sea or less.

In the case of cold pressure welding, the sealing performance is significantly lower than in the case of conventional 11g welding, and it is difficult to obtain a semiconductor device with a leakage amount within this standard leakage amount. For this reason, when the metal to be pressure welded is copper, cold pressure welding is sometimes carried out after the surface of the copper plate is plated with thin Ni or Or plating, but the effect is insufficient.

There is no known cold welding technology that achieves a complete metal bond over the entire surface of the welded part and achieves a degree of sealing within the standard leakage amount.

[Object of the Invention] The object of the present invention is to find the conditions for complete metal bonding of Ni-plated copper press-welded metal plates in a semiconductor device sealed by cold pressure welding and its manufacturing method, and to An object of the present invention is to provide a semiconductor device having high sealing performance equivalent to that of 11g welding, and a method for manufacturing the same.

[Summary of the Invention] The present invention provides that when pressure welding metal plates of N1-plated copper are sealed by cold welding, the main factors that determine the quality of the sealing performance are the plate thickness tcu of the pressure weld metal plates, N1 Plating thickness jN
Based on the knowledge that L and the deformation rate R of the pressure welded part,
This was achieved through repeated trials and processing and verification of the data using techniques such as multiple regression analysis. In another aspect of the present invention, a pressure-welded metal plate made of N1-plated copper is heat treated to
This was done based on the knowledge that more stable hermetic sealing can often be obtained by forming a mutual diffusion layer of CIJ and N1 at the interface between the plating layer and the copper plate and then performing cold pressure welding.

The present invention provides a semiconductor device that is hermetically sealed by stacking two pressure-welded metal plates on top of each other and cold-pressing an inner annular portion spaced a predetermined distance from the outer periphery of the metal plates. 1) The thickness tcu of the copper plate at the cold pressure welded portion of the two pressure welded metal plates is 200 μm to 800 μm.
(2) Ni plating is applied to the contact surfaces of the two copper plates of the cold welding portion, and the plating thickness jNL is 0.5 μm to 30 μm; (3)
The deformation rate R of the cold welded part is 10% to 85%, and (4) R is expressed as % and tcu and jNL are expressed as μm, and the respective numerical values of Rljcu and jNL are R
≧ 115+ 2,25tN, -0,21tcu...
This is a semiconductor device that is subjected to cold pressure welding to satisfy the relational expression (1).

In addition, the deformation rate R in the present invention is defined as: jclJs, the thickness of the copper plate before welding in the cold welded part; jcu', the thickness after welding.
Then, it is expressed by the following formula.

R= (tau tCu')/jCuX 1o
o (%) In another aspect of the present invention, in the method for manufacturing a semiconductor device, a pressure contact surface of two pressure contact metal plates each made of a copper plate having a thickness of 200 μm to 800 μm has a thickness of 0.
．． Ni plating of 5 μm to 30 μm is applied, and then the metal plate to be pressure welded is heat treated to form a mutual diffusion layer of copper and Ni at the interface between the copper plate and the Ni plating layer. This is a manufacturing method in which cold pressure welding is performed such that the deformation rate R satisfies the relationship of equation (1) above.

According to the present invention, the same sealing performance as conventional TIG welding can be obtained even in cold pressure welding technology, and the range of selection of the thickness of the copper plate etc. is expanded.

Furthermore, the patent application filed in 1986-120 is the basis of the priority claim.
The semiconductor device according to claim 1 of the specification of No. 682 is the semiconductor device according to claim 3 of the present specification, and the semiconductor device according to claim 1 of the specification of Japanese Patent Application No. 60-120682 is a semiconductor device according to claim 3 of the present specification. The semiconductor device recited in claim 2 is the same as one of the semiconductor devices recited in claim 6 of this specification.

[Embodiment of the invention] Trials of cold pressure welding of a pair of N1-plated copper metal plates to be pressure-welded were repeatedly performed, and the thickness tau, plating thickness tNL, and deformation rate R of the copper plates were determined to obtain uniform metal bonding. The limit conditions were investigated. In this trial, a pair of upper and lower pressure welding dies 7.8, each having a cylindrical shape and a press-fitting part 9 having a trapezoidal cross section, as shown in FIGS. Pressure welding was performed. The sealing performance after pressure bonding was determined by filling helium gas inside the semiconductor device and measuring the amount of helium gas leaking to the outside through the pressure bonded portion.

Thickness tNL of Ni plating relative to thickness tcu of copper plate
If it is too thick, not only will it be impossible to achieve a good sealing metal bond within the standard leakage amount, but the bond will not be able to be bonded at all. In this state, if only jNL is decreased to make it thinner than a certain limit value jNLmax, a perfect metallic bond can be obtained. Also jCu
When the values of and jNL are kept constant and the pressing force is changed,
Gold only occurs when the deformation rate exceeds a certain limit (when the deformation is increased).

Generic binding is obtained. The reason for this will be explained with reference to FIG. FIG. 1 is an enlarged sectional view of the pressure-welded portion 6, in which 3.4 is a metal plate to be pressure-welded, and 13 is a Ni plating layer.

The copper of the press-welded metal plate 3.4 to which pressure is applied by the upper and lower press-welding dies (see Figure 5) is a relatively soft metal, and the force received from the outer pressurizing surface of the press-welding dies is lateral, that is, metal Extends parallel to the plate surface. At this time, the copper base metal is deformed due to sufficient plastic flow. On the other hand, since Ni has a smaller elongation than copper, the Ni plated layer 1 on the bonding surface side
3 is cut near the center of the press-fitting part of the pressure welding die. When a further load is applied, the copper base material expands and the cut Ni plating layer is pulled to both sides. A copper base metal with advanced plastic flow appears between both ends of the cut N1 plating layer. This copper base material is a clean new surface without any oxide or other contamination, and when the new surfaces of the two copper plates are brought into contact with each other and pressurized, the two copper plates become complete gold scraps. leading to a union. The Ni plating layer covers the surface of the cleanly treated steel base metal, prevents the surface of the copper base metal from being contaminated by air, etc., and prevents the formation of new surfaces during cold welding. It is thought that it will make it easier. The above is the mechanism by which the Ni-plated copper base material forms a perfect metal bond, and is an extremely essential discovery in cold pressure welding technology.

This mechanism provides a consistent explanation of trial results.

For example, the Ni plating layer has a thickness jNL and a certain thickness tNLf
If it is thicker than flt1, the Ni plating layer will not break even if the copper base material stretches during the cold welding process, and therefore the new surface of copper cannot be exposed, making it impossible to obtain a desired metal bond. Also, there is a limit l1IRfflI with a deformation rate R
Even when it is smaller than n, the elongation of copper becomes insufficient,
It becomes impossible to break the Ni plating layer, and no metallic bond can be obtained.

On the other hand, the Ni plating layer is made thicker than a certain limit value jNLm,
By increasing the thickness of the copper base material and increasing the absolute amount by which the copper stretches, the Ni plating layer can be broken and a metallic bond can be obtained. However, in this case, the deformation value of the pressure welded part also increases, the copper in the pressure welded part hardens during processing, the hardness increases significantly, and the elongation of the copper decreases rapidly, making it impossible to break the Ni plating layer. In some cases, a metallic bond cannot be obtained.

As mentioned above, the three variables tCu+jNL and R are N
It is an extremely important parameter that determines the quality of cold pressure welding of I-plated copper metal plates to be pressure welded.

Next, Tables 1 to 3 show examples of the results of experiments on sealability conducted using tcLl, tNL, and R as parameters. In this experiment, tCu and tNL of the two pressure-welded metal plates are equal to each other, and R= (2jcu 2jcu') / 2jcuX
Set as 100 (%).

Table 1 Table 2 Table 1 shows tNL with tcu=400μm and R=60%.
These are the results of measuring the leak rate of helium gas while changing . A metallic bond with good sealing properties can be obtained when jNL is in the range of 1 μm to 15 μm.

Table 2 shows tcu"' 400μm, tNL=10
The leak rate is shown when R is changed in μm.

Metallic bonding cannot be obtained when R is less than 30%, but when R is 60%
With the above, a metal bond with extremely good sealing performance can be obtained.

Table 3 Table 3 shows jCu with tNL=ioμm and R=60%.
Shows the leak rate when changing. If tcU is less than 200 μm, the sealing performance is not good. 300μm
The sealing performance is considerably improved. When the thickness is 400 μm or more, a metal bond with extremely good sealing performance can be obtained.

Next, conduct experiments similar to those in Tables 1 to 3 [. 0゜jNL
FIG. 2 shows an example of experimental results conducted for various combinations of values of and R. Figure 2 shows tCII+ for obtaining a semiconductor device with extremely good sealing performance.
It is a chart showing limit values of tNL and R. The horizontal axis is the thickness of Ni plating (μm), and the vertical axis is the deformation rate R (%). For example, the parameter [. A straight line B when 0 is 400 μm indicates the limit values of the two variables tNL and R.

If tN = 5 μm, good results can be obtained if the deformation rate R is 40% or more. Also, t+yL = 15μm
In this case, R may be 60% or more. Therefore (.

, = 400 μm, R should take the value of each Ni plating thickness (Nu, line 8 or more (tolerance area indicated by diagonal lines in Figure 2)). Also, when R = 40%, jN
L needs to be 5 μm or less, and if R=60%, tNL should be 15 μm or less. Therefore, tNL may be set to be less than or equal to the value from straight line B to the vertical axis (the above-mentioned allowable range) for each value of R. The same view applies to the other straight lines A and C.

We statistically processed a large amount of experimental data with different parameter values from those illustrated in Tables 1 to 3 or Figure 2, and used multiple regression analysis to calculate the three variables jCu,
Equation (1) for determining the limit value existing between jNL and R was determined. This formula determines the limit values of the remaining variables when two variables are determined. -For example, j
If Cu = 400 μm, tN, = s μm, R should be 42.3% or more according to equation (1). Also, tNL=
5 μm and R=42.3%, it can be calculated from equation (1) that tau is required to be 400 μm or more. Similarly. . = 400 μm and R = 42.3%, jNL may be set to 5 μm or less from equation (1).

Equation (1), which determines the limit values of (Cu+ tNL and R) for obtaining good sealing performance, is based on the helium gas leak rate IX 110-8ato・
This was determined as being within QC/SeC. However, the leak rate limit sensitivity of the detection device is approximately 1010-1 Oa.
to cc/sec, and the encapsulated He is 100%
This is the case of 1-1e. However, practical tCIJ
+ The values of tNt and R are mechanical strength other than sealing property,
It is also constrained by conditions such as manufacturing technology. Regarding tau, if it is less than 200 μm, there are drawbacks such as insufficient mechanical strength, and if it is more than 800 μm, there is a risk of applying excessive force to the envelope during assembly, handling, etc.
to 800 μm. Regarding ENL, if it is less than 0.5 μm, it will be difficult to plate the copper base metal surface uniformly, and if it is more than 30 μm, the deformation ω of the pressure welded part will become large and it will be difficult to break the Ni plating layer due to hardening of the copper, etc. It is necessary to limit the thickness to .5 μm to 30 μm. Regarding R, if the deformation is less than 10%, the N1 plating layer cannot be guaranteed to break, and if it is more than 85%, the mechanical strength against the swelling phenomenon of the envelope will be insufficient.
Limited to 5%.

Next, an embodiment of the manufacturing method of the present invention will be described with reference to FIGS. 8 to 10. FIG. 8 shows the manufacturing process, and FIG. 8(a) shows the upper assembly 22 and lower assembly 23 in a state in which no semiconductor chip is housed. The upper assembly 22 is made by assembling the electrode 1, the insulating envelope 2, and the upper pressure-welded metal plate (copper plate) 3 by brazing or the like, and the lower assembly 23 consists of the lower pressure-welded metal plate (copper plate) 4 and The electrode 5 is assembled by brazing or the like. The thickness Cu of the copper plates of the upper and lower press-welded metal plates 3 and 4 is both 400 μm. Next, press-welded metal plates 3 and 4
N: plating 13 is applied to each pressurized surface by a known method so that the plating thickness jNL is 13 μm. In this case, there is no problem even if the exposed surfaces on the front and back of the pressure-welded metal plate are completely covered with N1 plating. FIG. 8(b) shows this state, and is an enlarged sectional view of a portion P of the press-welded metal plate 3 surrounded by the broken line in FIG. 8(a). Next, the upper and lower assemblies 22 and 23 are heat treated at a temperature of about 500°C to 800°C in a hydrogen atmosphere for several minutes to several tens of minutes, so that the copper plate of the pressure welded Z plate and the Ni plating layer are bonded together. A mutual diffusion layer 14 of copper and N1 is formed at the interface.

The thickness of the mutual diffusion layer 14 is 3 μm. Figure 8 (
C) schematically shows this state, and is an enlarged sectional view of a portion Q of the pressurized surface surrounded by the broken line in FIG.

Thereafter, the semiconductor pellets 1- and the like are housed in the upper and lower assemblies 22 and 23, and the inner annular portions of the two pressure-welded metal plates are cold welded from the outer periphery to the inner annular portion by a known method to hermetically seal them. Obtain a semiconductor device. The deformation rate R of the metal plate to be welded during cold welding is 10% to 85%, and the above-mentioned "R≧115+2,25tN, -0,21tcu
−・−(1) J must be satisfied. In this example, the value on the right side of equation (1) is tN, = 13 μm,
Since tou=400μm, 60.・It becomes 25.

Therefore, pressure is applied so that R=65%. As a result of measuring the helium gas leak rate of this semiconductor device,
At 1×10"(atOl-cc/sec") or less, good airtight sealing was obtained, which was undetectable even when measured with the highest sensitivity of the detection device. XMA (X-ray Micro
Analisi S) analysis photograph results show that no Ni element was observed at the pressure weld interface, confirming that the bond was a perfect bond between new surfaces of copper. Furthermore, FIG. 9 shows the results of XMA ray analysis of a sample in which the same copper base material was subjected to the same Ni plating and heat treatment. The horizontal axis in Fig. 9 is the direction perpendicular to the interface between the copper plate and the N1 plating layer in the sample cross section
The distance in the C+-c2 direction in Figure (C) is shown, and the vertical axis shows each characteristic X-ray dose at each position of copper or Ni. In the figure, the range where the characteristic X-rays of steel and Ni are both observed is the interdiffusion layer 14, and its left and right (9th
In the figure) are a copper plate portion 16 made of substantially only copper and a Ni portion 15 made of only Ni.

Next, the thickness of the copper plate j cu N N j The plating thickness pupil and deformation rate R are the same as in the previous example, and the thickness t of the interdiffusion layer is changed by changing only the heat treatment conditions (treatment temperature or treatment time) after Ni plating. The same measurements as in the above example were performed for the case where the thickness was 10 μm. In this case, the helium gas leak rate of the semiconductor device is 1 xlO-' (atom-c
c/sea), which is not a desirable value. In addition, the result of the XMA analysis photograph of the pressure weld interface shows that N1
The presence of elements was partially observed, and complete bonding of the new copper surfaces was not obtained. FIG. 10 corresponds to FIG. 9, and the thickness t of the mutual diffusion layer is 10 μm.

Experiments similar to those in the above example were repeated on a large number of samples, and various notes on cold pressure welding when heat treated were investigated.

As a result, the conditions for cold welding to obtain airtightness when heat-treated and providing an interdiffusion layer are the above-mentioned copper plate thickness 'cu % N + plating thickness 1. and the respective ranges of the deformation rate R and [. It was confirmed that it is necessary to satisfy the relationship of formula (1) between 116.8 and 116.8. In this case, in order to obtain more stable airtightness, the thickness t of the interdiffusion layer should be t≦ with respect to the Ni plating thickness jNL before heat treatment.
In this embodiment, it is desirable that 1/2tNL and t≦10 μm.

Note that the interdiffusion layer between copper and Ni is such that copper atoms in the copper plate enter the N1 plating layer at the interface between the copper plate and the Ni plating layer.
It is formed by the diffusion of Ni atoms in the i-plated layer into the copper plate, and is often produced in a solid state, but it may also include some alloy ellipses of copper and Ni that have been melted and solidified.

According to the manufacturing method of the present invention, more stable airtightness can be obtained in cold welding, but in addition, gas, dust, or Foreign substances such as oxides are removed, and the reliability of the semiconductor device during actual operation can be improved.

W of the patent claim of the present invention! The semiconductor device described in item 2 is a semiconductor device obtained by using the manufacturing method of the present invention among the semiconductor devices of the present invention. Further, the semiconductor device according to claim 3 is a preferred actual IJI mode of the semiconductor device of the present invention when the manufacturing method of the present invention is not used.

Further, the semiconductor device according to claim 4 may be manufactured using the manufacturing method of the present invention or not! ! The actual M mode is particularly desirable from the viewpoint of one-dipping technology or production control.

Further, a semiconductor device according to claim 5 is a semiconductor device using the manufacturing method of the present invention, and is a desirable embodiment of the semiconductor device according to claim 2 or 4.

In order to ensure the effects of the present invention, it is desirable that the distance of the annular cold welded portion from the outer peripheral edge of the metal plate to be welded be 0.2 mm or more.

[f! , Bright Effects] According to the semiconductor device and the manufacturing method thereof of the present invention, it has become possible to supply a semiconductor device having a sealing performance equivalent to that of TIG welding 1F by cold pressure welding technology.

Being able to seal by cold pressure welding significantly improves work efficiency compared to TiQ welding. That is, it has the advantage of being simple, fast, and inexpensive.

Furthermore, the present invention makes it possible to completely seal a semiconductor device, which conventionally had slight leakage, and significantly improves its reliability over a long period of time.

Furthermore, the present invention expands the selection range of jcuq tNL and R, making it possible to use new combinations of three variables, increasing the degree of freedom in design and facilitating process control.

Further, by the manufacturing method of the present invention, the inner walls of the device such as the envelope were cleaned, and a highly reliable product was obtained.

Note that the technical idea of the present invention is applied not only to the sealing of semiconductor devices but also to many fields that require metal bonding.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a cold welded portion of a semiconductor device according to the present invention, and FIG. A chart showing the limit values of u, tN, and R; FIG. 3 is a partially cutaway side view of the semiconductor device of the present invention;
4 is a plan view of the semiconductor device shown in FIG. 3, FIG. 5 is a partially cutaway side view showing a state in which the semiconductor device is cold welded to a pressure welding die using a clamp/V, and FIGS. 7 is a cross-sectional view and a plan view of the pressure welding die, and FIGS. 8(a) to 8(c) show the steps of the manufacturing method of the present invention.
) is a side view of the upper and lower assemblies, and (b) is a side view of the upper and lower assemblies.
Figure 9 (C) is an enlarged cross-sectional view of the pressure-welded metal plate after heat treatment, Figures 9 and 1.
Figure 0 shows the XMA of the interface between the copper plate and the Ni plating layer after heat treatment.
Figure 4 shows an example of the line analysis results. 3.4... Pressure welded metal plate (copper plate), 6... Annular part (cold pressure welded part), 13... Ni plating layer, 1
4... Interdiffusion layer, 15... Nickel portion consisting essentially only of nickel, 16... Copper plate portion consisting essentially only of copper, 21... Semiconductor device, l...
・Predetermined distance, jcu...pressure welded metal plate (copper plate)
The thickness of the cold welded part before welding (μm), tcu'
...Thickness of the cold welded part after pressure welding of the metal plate (copper plate) to be pressure welded (μm), tNL...Thickness of N1 plating μm)
m), t... Thickness of interdiffusion layer μm), R...
・Deformation rate (%) of cold welded part. Patent applicant: Toshiba Corporation Figure 1 Figure 2 Figure 5 Figure 8 Figure 9 Figure 10

Claims (1)

[Scope of Claims] 1. A semiconductor device that is hermetically sealed by stacking two pressure-welded metal plates on top of each other and cold-pressing an inner annular portion spaced a predetermined distance from the outer periphery of the metal plates, The base material of the cold pressure welded portions of the two metal plates to be pressure welded are both copper plates with a thickness of 200 μm to 800 μm,
The pressure welding surfaces of the two copper plates of the cold welded portion are each plated with nickel to a thickness of 0.5 μm to 30 μm, and the deformation rate expressed as a percentage of the cold welded portion is 10 to 85. At the same time, the value of this deformation rate is calculated by multiplying the thickness of the copper plate in μm by 0.21 from the sum of 115 and the value obtained by multiplying the thickness of the nickel plating in μm by 2.25. A semiconductor device characterized in that the value is not smaller than the subtracted value. 2. An interdiffusion layer of copper and nickel is provided at the interface between the copper plate and the nickel plating layer and cold pressure welded, and the thickness of the interdiffusion layer is 0.25 μm to 10 μm and consists essentially of copper only. 2. The semiconductor device according to claim 1, wherein the copper plate portion has a thickness of 199.75 μm to 790 μm, and the nickel portion consisting essentially of nickel has a thickness of 0.25 μm to 20 μm. 3 The thickness of the copper plate is 200 μm to 600 μm,
The semiconductor device according to claim 1, wherein the nickel plating has a thickness of 0.5 μm to 25 μm. 4 The thickness of the copper plate is 400 μm to 600 μm,
The semiconductor device according to claim 1, wherein the nickel plating has a thickness of 1 μm to 25 μm. 5. An interdiffusion layer of copper and nickel is provided at the interface between the copper plate and the nickel plating layer, and the interdiffusion layer is cold-pressed, and the thickness of the interdiffusion layer is 0.5 μm to 10 μm, and the copper plate is substantially made of copper. The thickness of 399.5μm to 590μm
The semiconductor device according to claim 2 or 4, wherein the thickness of the nickel plating layer substantially made of nickel is 0.5 μm to 15 μm. 6. The semiconductor device according to any one of claims 1 to 5, wherein the inner annular portion separated by 0.2 mm or more from the outer peripheral edge of the metal plate to be pressure-welded is cold-welded. 7. A method for manufacturing a semiconductor device in which two metal plates to be pressure-welded are stacked on top of each other and the inner annular portion separated by a predetermined distance from the outer periphery of the metal plates is cold-welded and hermetically sealed, with a thickness of 200 μm. A thickness of 0.5 μm is applied to each pressure contact surface of two pressure contact metal plates made of copper plates with a thickness of 0.5 μm to 800 μm.
After applying nickel plating to a thickness of 30 μm to 30 μm, and then heat-treating the metal plate to be welded under pressure to form a mutual diffusion layer of copper and nickel at the interface between the copper plate and the nickel plating layer, it was expressed as a percentage of the cold welded area. Deformation rate value is 10 to 8
5, and the value of this deformation rate is the value obtained by multiplying the thickness of the nickel plating in μm by 2.25, and 11
5. A method for manufacturing a semiconductor device, characterized in that cold welding is carried out so as not to be smaller than a value obtained by subtracting a value obtained by multiplying the thickness of the copper plate in μm by 0.21 from the sum of 5 and 5. 8. The thickness of the interdiffusion layer is not more than half the thickness of the nickel plating before heat treatment, and is 10 μm.
8. The method of manufacturing a semiconductor device according to claim 7, wherein the thickness does not exceed . 9. The method of manufacturing a semiconductor device according to claim 7 or 8, wherein the inner annular portion separated by 0.2 mm or more from the outer peripheral edge of the metal plate to be pressure-welded is cold-welded.