JPS59144139A - Manufacture of molybdenum-based composite plate - Google Patents

Abstract

PURPOSE:To obtain a clad plate which has good adhesiveness by forming thin layer of nickel on one or both side overall surfaces of a molybdenum base plate, superposing metal plates on the entire surfaces and then heating under pressure the plate in reducing atmosphere. CONSTITUTION:Tough pitch copper plate which has, for example, 420mm. in length, 40mm. in width and 1mm. in thickness, is dipped in an organic solvent, and cleaned by supersonic wave to degrease the surfaces of the plate. After the surfaces of sintered molybdenum plates which respectively have 380mm. in length, 35mm. in width and 420mm. in length, 40mm. in width, and 1mm. in thickness are, on the other hand, similarly degreased, the entire both surfaces of the plates are plated by nickel in thickness of approx. 1mum, and heated at 700 deg.C for 1hr to diffuse the nickel in the molybdenum. Then, the copper plates are superposed on the both overall surfaces of the molybdenum plates, mica plates are contacted on the outermost layers of the plates, set to a pressurizing jig, and the superposed plates are pressurized and kept in pressure contacting state. These plates are heat treated at 1,000 deg.C in hydrogen atmosphere for 2hr, then cooled in the furnace in inert gas atmosphere, and then removed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a molybdenum substrate composite plate with good adhesion, which is used as a temperature compensating plate for a semiconductor device, in which a plate of another metal or alloy is adhered to one or both sides of a molybdenum plate.

Since molybdenum has a coefficient of thermal expansion close to that of silicon, it is used as a temperature compensating plate for preventing damage to silicon elements of semiconductor components due to thermal strain.

In order to simplify the bonding process for this molybdenum temperature compensating plate, a clad plate in which copper, silver, or the like is bonded to one or both sides of a molybdenum plate is sometimes used. However, such a clad plate is prone to problems such as peeling of the cladding surface due to heating when bonding a silicon element onto a metal ladder or repeated heat cycles during use of a semiconductor device, so a clad plate with high adhesion strength is It was requested.

Sintered materials are generally used as molybdenum plates, but they have weak mechanical properties and high hardness, and the desired high adhesion strength cannot be obtained using the roll crimping method commonly used for manufacturing clad plates. The applicant previously proposed a method for manufacturing a molybdenum-based composite plate with good adhesion by solving the above-mentioned drawbacks, in the patent application No. 37-22 IO'.
No. 1I was filed. This method involves forming a thin coating layer of copper, gold, silver, or their alloys on a molybdenum substrate, and then coating a thin layer of copper, which has the same or larger dimensions as the molybdenum substrate.
A composite plate with good adhesion can be obtained by stacking nickel, gold, silver metal plates or their alloy plates and joining them under heat and pressure in a vacuum, inert or reducing atmosphere, and particularly good adhesion. When high performance is required, the dimensions of the metal plate to be clad are preferably eight times or more larger than the dimensions of the molybdenum substrate in both width and length.

As a result of various studies, the inventors have discovered that by coating a molybdenum substrate with nickel or a nickel alloy, a molybdenum substrate composite plate with even better adhesion than the above method can be obtained.

In the present invention, a thin coating layer of nickel or nickel alloy is formed on one or both sides of a molybdenum substrate, and then a metal plate having the same width and length as the substrate or larger is superimposed on the thin coating layer, and then vacuum Bonding is performed by pressurizing and heating in an inert or reducing atmosphere.

In the present invention, it is necessary to previously form a coating thin layer of nickel or a nickel alloy on the surface of the molybdenum substrate to be clad, and the nickel alloy is preferably nickel-copper, nickel-gold, or nickel-silver alloy.

As a coating method, general methods such as plating, vapor deposition, welding, etc. can be used after cleaning and degreasing the surface to be coated. The optimal thickness of the thin coating layer is about 0.3 to sttm. Preferably, these thin coating layers are diffused into the molybdenum substrate by heat treatment or the like.

In the manufacturing method of the present invention, copper, nickel, gold, silver metal plates, or alloy plates thereof are suitable as the metal to be clad, and among these, copper is the most preferable, and the width and length of the molybdenum substrate A metal plate or alloy plate with the same dimensions may be stacked with the thin coating layer of a molybdenum substrate on which a thin coating layer has been formed, and then subjected to pressure and heat treatment. When the plate is laminated with a thin coating layer of a molybdenum substrate on which a thin coating layer has been formed and subjected to pressure and heat treatment, the adhesion becomes even better.

In this case, if the dimensions of the metal to be cladded are 7 times or more the width and length of the molybdenum substrate, the bonding strength will be even higher.

The heat treatment must be carried out in a vacuum, inert or reducing atmosphere, and an oxidizing atmosphere should be avoided.

The bonding strength can be maximized by heat treatment at a temperature slightly lower than the melting point of the metal or alloy to be clad, but the width and length of the molybdenum substrate
When the temperature is more than twice that, the adhesive strength can be improved up to a temperature range of about 4t000 lower than the melting point than when no thin coating layer is provided. However, when the dimensions of the metal plate to be clad are the same as those of the molybdenum substrate, by maintaining the temperature within a range of 3 soc below the melting point, the bonding strength can be improved compared to the case where no thin coating layer is provided.

Pressure during heat treatment can be applied by means such as clamping the material in an appropriate jig and tightening it with pressure screws so that the thin coating layer of the molybdenum substrate and the cladding material are in close contact with each other. Preferably, a mica plate or the like is interposed on the contact surface with the material to prevent sagging.

The cladding material may be bonded to a molybdenum substrate on one or both sides depending on the application.The cladding material may be made of different materials on both sides of the substrate, or the cladding material may be bonded between two or more molybdenum substrates. It is also possible to produce composite plates in which multiple layers are stacked together.

Examples will be described below.

Example/An oxygen-free copper plate having a length of 2 om, a width of 11 Qm*, and a thickness of 1/2 mm is immersed in an organic solvent and subjected to ultrasonic cleaning to degrease the surface. On the other hand, after degreasing the surface of a sintered molybdenum plate with a length of 3g0mm, a width of 3j; Nickel plating is applied and heated in an inert atmosphere at 700C for 2 hours to diffuse nickel into molybdenum, and then the degreased copper plate is placed on both sides of this molybdenum plate in a clean environment, so that the copper plate is better than the molybdenum plate. When the amount is large, the copper plate is overlapped on the entire surface so that it protrudes around the molybdenum plate, the mica plate is placed on the outermost layer, and the plate is set in a pressure jig to press the stacked plates together. Place the stacked plates together with the pressure jig on a boat and charge it into the furnace, /θOOC.

It was heat treated in a hydrogen atmosphere for 2 hours, then cooled in a furnace in an inert atmosphere, and then taken out. A sample with a length of Q mm and a width of about 3 mm was cut out from the center of the obtained composite plate, and
Use a vise and chuck to hold both ends of the sample in the thickness direction at 39 mm intervals, and hold the chuck at 9 degrees. Turn clockwise, return to original position, then turn counterclockwise 900° and return to original position. Counting the twisting test as 7 times, the number of times until a crack occurs in the sample is expressed as the average value of 10 samples, and the adhesion is measured. We investigated the quality of the product.

Examples, 2 to 7 Using the same materials as in Example//, only the temperature at which the clad material was brought into contact with the molybdenum plate and heated under pressure was set to 900 and 0.
Xg00.7!0.700. A! QC (1) A torsion test was conducted in the same manner as in Example 1 except that the temperature was varied.

Example g A silver plate containing 3% by weight of copper with a length of 11λ0, a width of 10, and a thickness/width was degreased and cleaned, while a sintered molybdenum plate with the same dimensions as Example/ was prepared, Apply the same treatment,
The degreased copper-containing silver plate is brought into contact with both sides of this molybdenum plate in the same manner as in Example/, and the g00Cc solidus line gq
Or):) was heat treated in a hydrogen atmosphere for 2 hours, and then cooled in a furnace in an inert atmosphere. Samples were cut out from the obtained composite plate in the same manner as in Example 1 and subjected to a torsion test.

The same oxygen-free copper plate as Comparative Example/Example/ was degreased and cleaned, and the same oxygen-free copper plate as Example/
The same sintered molybdenum plate was degreased, but the degreased oxygen-free copper plate was brought into pressure contact with both sides without applying a thin surface coating layer, and treated in a hydrogen atmosphere at 10θOC for 2 hours. A sample was cut out from the composite plate obtained by cooling in a furnace in an active atmosphere and subjected to a torsion test in the same manner as in Example.

Comparative Example Col B The same oxygen-free copper plate as Example / was degreased and cleaned, and the same sintered molybdenum plate as Example / was degreased, and then copper plating with a thickness of about /μm was applied to both surfaces. Heat treatment was performed in the same manner in an active atmosphere, and the degreased oxygen-free copper plates were superimposed on both sides of the molybdenum plate in the same manner as described in Examples/100, qoo, g3θ, goo, 7 left θC.
Pressure and heat treatment was performed at various temperatures, and a torsion test was conducted in the same manner.

The test results of the above Examples/~g and Comparative Examples/~B are
They are summarized in the table.

Chapter / Table Torsion test amount / Oxygen-free copper nickel 1000 9.
,? g, g From the results in the table above, if the dimensions of the clad material are more than double the width and length of the molybdenum substrate, the heating temperature will be the melting temperature of the oxygen-free copper of Examples A/-B: 70 which is about tioo c lower than y C
The adhesion of the sample up to 0C is very superior to that of the comparative example, which does not have a thin coating layer applied to the molybdenum substrate, but Example A7 was compared by heating at a temperature more than ttoo C below the melting temperature. There is no noticeable difference compared to example /, and when the size of the cladding material is the same as that of the molybdenum substrate, the heating temperature is about 350C lower than the melting temperature up to 7T QC, showing good adhesion. Ta. Moreover, Ag-Cu of Example g
The heating temperature of the plate is about 7°C higher than the solidus line of this alloy, which is 70°C.
0 tZ' is low, indicating excellent adhesion.

Furthermore, as is clear from a comparison between Examples/~S and Comparative Examples λ~B, the adhesion of nickel, which is the coating material to the molybdenum substrate used in the present invention, is significantly greater than that when coated with copper. It shows that it is excellent.

Claims (1)

[Claims] (1) A thin coating layer of nickel or nickel alloy is formed on one or both sides of a molybdenum substrate, and a thin coating layer of copper, nickel, gold, or silver with a width and length equal to or greater than that of the molybdenum substrate is formed on the thin coating layer. A method for producing a molybdenum-based composite plate, which comprises stacking metal plates or alloy plates thereof on their entire surface and joining them by heating and pressing in a vacuum, inert or reducing atmosphere.