JP3037485B2 - Thermal conductive material and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor such as metal, ceramics, Si, plastics, etc. for efficiently radiating heat generated by a semiconductor chip to the outside, such as a heat dissipation board for mounting a semiconductor chip or a material for a lead frame. The coefficient of thermal expansion and the thermal conductivity are arbitrarily changed so that both the matching of the thermal expansion coefficient with the material to be adhered and the good thermal conductivity can be achieved. After joining the high thermal expansion metal foil to both surfaces of the low thermal expansion metal plate by pressing and integrating them, the three-layer material provided with a large number of through holes in the thickness direction is brought to room temperature or above the recrystallization temperature. By pressing against one or both sides of the heated high thermal expansion metal plate, the thermal expansion coefficient, without changing the thickness ratio and through hole area ratio of these metal plates with high bonding strength selected
The present invention relates to a heat conductive material having a variable heat conductivity, uniform heat reception, an improved heat diffusion effect, no surface micropores, and excellent adhesion of thin films such as plating and brazing material, and a method for producing the same.

[0002]

2. Description of the Related Art Integrated circuit chips (hereinafter referred to as "chips") of semiconductor packages, especially LSIs for large computers
And ULSIs have been moving toward higher integration and higher calculation speed, and the amount of heat generated by the increase in power consumption during operation has become extremely large. The chip has a large capacity and generates a large amount of heat. If the coefficient of thermal expansion of the substrate material is significantly different from that of the chip material such as silicon or gallium arsenide, there is a problem that the chip is peeled or cracked.

Along with this, the design of a semiconductor package has also been
In consideration of heat dissipation, the substrate on which the chip is mounted also needs to have heat dissipation, and the substrate material is required to have high thermal conductivity. Therefore, the substrate is required to have a thermal expansion coefficient close to that of the chip and a high thermal conductivity.

Various configurations have been proposed as conventional semiconductor packages. For example, there is a configuration in which a radiating fin is provided on a substrate.
Composite materials for heat dissipation substrates such as u-Mo or Cu-W alloys (JP-A-59-141247, JP-A-62-29
No. 4147) has been proposed. Although the composite has a practically satisfactory coefficient of thermal expansion coefficient and thermal conductivity, it is heavy and brittle because Mo, W, etc. have a high density, and therefore, in order to obtain predetermined dimensions, non-grinding or the like is required. The forming process has to be performed by plastic working, so that the processing cost is high and the yield is low.

In a resin-sealed semiconductor package,
Since the lead frame not only serves as a path for electrical connection to the outside of the chip but also plays an important role as a path for dissipating heat generated in the chip, lead frames made of copper alloy are often used.

However, for applications requiring high reliability, copper alloys have low mechanical strength, poor matching of the coefficient of thermal expansion with the chip, and separation of the bonding interface between the chip and the island is a concern. Therefore, a semiconductor package employing a Ni-Fe alloy having a low coefficient of thermal expansion, such as a 42% Ni-Fe alloy, has been proposed in view of the matching of the coefficient of thermal expansion with the chip. However, Ni-Fe-based alloys have poor thermal conductivity, and thus do not have sufficient heat dissipation properties to satisfy current requirements. In addition, the difference in thermal expansion between the chip and the sealing resin is very large, and even when the thermal expansion coefficient between the lead frame and the chip is good, the matching between the lead frame and the resin is poor. It has been difficult to completely prevent cracks from occurring in the steel.

Further, in the ceramic semiconductor package, in order to perform Al wire bonding and glass sealing, a lead frame is often made of a Ni—Fe alloy having Al provided in a bonding area and a sealing position.
However, as described above, Ni-Fe alloys have poor heat dissipation properties, and have a problem in matching thermal expansion coefficients with ceramics.

In order to solve the above-mentioned problem of matching of the coefficient of thermal expansion and / or thermal conductivity in a semiconductor package, the applicant of the present invention has proposed a low thermal expansion metal plate having a required through hole in a thickness direction in a high thermal expansion metal plate. And a high thermal expansion metal foil is pressed against both surfaces of a core material in which the high thermal expansion metal is exposed to the surface of the low thermal expansion metal plate from the through hole, and the thickness ratio and the through hole area ratio of these metal plates are appropriately selected. By doing
A thermally conductive composite material with variable thermal expansion coefficient and thermal conductivity, uniform heat reception, and improved thermal diffusion effect, with no surface pores and excellent adhesion of thin films such as plating and brazing material. (Japanese Patent Application No. 2-40550).

[0009]

In order to obtain the above-mentioned heat conductive composite material, first, a punching process is carried out by a press to form a large number of small holes to form a mesh, and a low-heat material such as a Kovar plate wound after annealing is wound. After unwinding the expanded metal sheet coil from above and below when unwinding a high thermal expansion metal sheet coil such as a copper sheet, roll-joining with a large-diameter roll in cold or warm and diffusion annealing to obtain a core material Further, a high thermal expansion metal foil such as Cu, Al or the like unwound from above and below this core material is superposed, pressed and joined by a rolling roll in a cold or warm state, and diffusion-annealed.

In the production of this heat conductive composite material, a high thermal expansion metal foil such as Cu, Al or the like is superimposed on the above core material and cold-welded, but if the rolling force is increased in order to increase the bonding strength, the surface of the core material is increased. The shape of the exposed surface of the high thermal expansion metal such as Cu or Al becomes a long or elliptical shape from a circle or an ellipse, and the surface area ratio between the selected high thermal expansion metal and the low thermal expansion metal changes, so that the thermal expansion coefficient and / or the thermal conductivity are changed. There is a problem that the thermal expansion coefficient fluctuates and anisotropic thermal expansion coefficient occurs. Further, in the above-described manufacturing process, since the pressing step is repeated twice, the rolling reduction becomes high, which increases the spreading amount of the core material and causes the shape of the exposed surface of the high thermal expansion metal to be greatly deformed.

In order to cover the surface of the core material with a high thermal expansion metal foil such as Cu and Al, plating may be considered in place of the above pressure welding method. The plating solution remains at the boundary between the high thermal expansion metal and the low thermal expansion metal on the surface of the material, which may evaporate during subsequent diffusion annealing, causing blistering or peeling of the plating. There is a problem that takes time.

According to the present invention, the uniformity of heat reception and the improvement of the heat diffusion effect are achieved, there is no fine pores on the surface, the adherence of a thin film such as a plating or brazing material is excellent, and the heat of a bonding partner material such as a chip or a sealing resin is improved. Excellent consistency with expansion coefficient and good thermal conductivity,
The purpose is to provide a heat conductive material that can arbitrarily select the coefficient of thermal expansion and the thermal conductivity according to the application and purpose, and when manufacturing this heat conductive material by pressure welding, the shape of the through hole provided in the low thermal expansion metal plate A method for producing a heat conductive material capable of obtaining a selected coefficient of thermal expansion and / or thermal conductivity without significant change and improving the bonding strength between the laminated high thermal expansion metal and low thermal expansion metal The purpose is to provide.

[0013]

SUMMARY OF THE INVENTION The present invention relates to a high-thermal-expansion metal plate on one or both surfaces, and a low-thermal-expansion metal plate on one surface.
Integrating expanded metal foil and providing many through holes in the thickness direction
The two-layer material is arranged such that the high thermal expansion metal foil is disposed on the outer surface.
Laminated and integrated, formed on the outer surface of high thermal expansion metal foil
A thermally conductive material, wherein a part of the high thermal expansion metal plate from the through-hole is <br/> exposed invade being. Also,
The invention of the present invention relates to a low thermal expansion
High thermal expansion metal foil is integrated on both sides of the metal sheet
3 layers with many through holes are integrated
From the through hole formed on the outer surface of the high thermal expansion metal foil
The feature is that a part of the high thermal expansion metal plate enters and is exposed.
Heat conductive material.

Further , the present invention provides a two-layer material having a large number of through-holes in the thickness direction after pressure-welding a high-thermal-expansion metal foil to one side of a low-thermal-expansion metal plate to form a two-layer material. On one or both sides of the high-thermal-expansion metal plate heated to a high-expansion metal foil, the high-thermal-expansion metal foil is pressed and laminated so as to be arranged on the outer surface, and the high-thermal expansion metal foil is
Part of the high thermal expansion metal plate enters through the formed through hole
A method for producing a heat conductive material, characterized by being exposed.

Further, the present invention provides a three-layer material having a plurality of through-holes in the thickness direction after a high-thermal-expansion metal foil is pressed and integrated on both surfaces of a low-thermal-expansion metal plate, and is then subjected to room temperature or recrystallization temperature or higher. with integrally laminated in pressure contact with the one side or both sides of the high thermal expansion metal plate heated to, outside the high thermal expansion metal foil
Part of the high thermal expansion metal plate from the through hole formed on the surface
A method for producing a heat conducting material characterized in that exposed to invade.

Further, according to the present invention, in the heat conductive material having the above-mentioned structure, the high thermal expansion metal plate may be made of Cu, Cu alloy, Al,
One of the Al alloys, the low thermal expansion metal plate is Mo,
Ni-Fe based alloy containing 0 to 50 wt% Ni, 25
Ni containing up to 35 wt% Ni and 4 to 20 wt% Co
-Co-Fe-based alloy, any of W, the high thermal expansion metal foil is made of any of Cu, Cu alloy, Al, Al alloy, and among the heat conductive materials substantially constituting the five-layer material,
The thickness t _{1 of} the high thermal expansion metal plate and the thickness t ₂ of the low thermal expansion metal plate
, And the thickness t ₃ of the high thermal expansion metal foil _{layer, t 1 = 1t 2 ~5t 2} , t 3 ≦ 1/10 t 2 t 1 + t 2 = 0.1~30mm, satisfies t ₃ = 2 to 100 m Is preferred.

Further, according to the present invention, in the heat conductive material having the above-described structure, a metal plating made of any one of Cu, Al, Ni, and Sn is applied to a required position on at least one main surface of the heat conductive material. It is a heat conductive material characterized by the following. For example, a Ni-Fe alloy having a large number of through-holes in the thickness direction by pressing a high-thermal-expansion metal foil on one or both sides of both main surfaces of a high-thermal-expansion metal plate of Cu, Al, or the like, Ni-C
A low thermal expansion metal plate such as an o-Fe alloy is integrated, a high thermal expansion metal is exposed to the surface of the low thermal expansion metal plate from the through hole, and the metal plating is applied to a required position of the outermost high thermal expansion metal foil. By applying processes such as press-fitting and laminating by applying processing such as brazing material attachment, heat conductive materials for various uses such as heat dissipation substrates for mounting chips such as ceramic packages and metal packages, lead frames, etc. can be obtained. .

[0018]

The heat conductive material according to the present invention has a plurality of through holes in the thickness direction by pressing a high thermal expansion metal foil on at least one outer surface of one or both surfaces of a high thermal expansion metal plate heated to room temperature or a recrystallization temperature or higher. The provided low-thermal-expansion metal plate is press-contacted, and the high-thermal-expansion metal is exposed and integrated with the high-thermal-expansion metal foil surface from the through hole, mainly by selecting the thickness ratio of the high-thermal-expansion metal plate. The coefficient of thermal expansion can be changed arbitrarily, and the high thermal expansion metal used as the core material is made of a high thermal conductive metal, and the exposed area of the high thermal expansion metal and the low thermal expansion metal plate fitted in the through hole on the same plane. The thermal conductivity can be changed arbitrarily by appropriately selecting the ratio,
Material selection and combination of high thermal expansion metal plate and low thermal expansion metal plate,
In addition, by selecting the thickness ratio and the exposed area ratio, various applications, the thermal expansion coefficient and the thermal conductivity can be set according to the purpose,
Many types of heat conductive materials can be provided.

The manufacturing method according to the present invention comprises a simple step of pressing a high-thermal-expansion metal plate and a low-thermal-expansion metal plate provided with a large number of through holes in the thickness direction by pressing a high-thermal-expansion metal foil on one or both surfaces. A conductive material can be obtained. In this case, since only one press-contact is performed, the shape of the exposed surface of the high-thermal-expansion metal is small, and the high-thermal-expansion metal and the low-thermal-expansion metal plate selected in advance are exposed on the same plane. A heat conductive material having a required coefficient of thermal expansion and thermal conductivity can be obtained without changing the area ratio. Further, in the manufacturing method according to the present invention, since the high thermal expansion metal foil is pressed against the low thermal expansion metal plate before the through hole is provided, air is blown around the through hole when the low thermal expansion metal plate and the high thermal expansion metal plate are pressed against each other. There is little entanglement, the peeling of the high-thermal-expansion metal foil is prevented, and a uniform and excellent outer surface is obtained. Therefore, there is no need to clad or plate the high-thermal-expansion metal foil again.

The thermal conductive material according to the present invention has a high thermal expansion coefficient when a high thermal expansion metal plate is pressed against a high thermal expansion metal foil on one or both sides and a low thermal expansion metal plate provided with a large number of through holes in the thickness direction. Since the metal plate is heated to a temperature higher than the recrystallization temperature, and furthermore, the high thermal expansion metal materials pressed against the low thermal expansion metal plate are pressed together, a high pressing strength can be obtained even with a small rolling force, and the metal plate is provided on the low thermal expansion metal plate. There is little deformation of the shape of the through hole, and a predetermined heat can be obtained without changing the exposed area ratio (through hole area ratio) of the high thermal expansion metal and the low thermal expansion metal plate fitted in the through hole selected in advance on the same plane. Expansion coefficient and thermal conductivity are obtained. In particular, when a high thermal expansion metal foil is pressed against one or both surfaces and is pressed against a low thermal expansion metal plate provided with a large number of through holes in the thickness direction, the high thermal expansion metal plate is heated to a temperature higher than the recrystallization temperature to reduce the rolling reduction force. The high thermal expansion metal fits into the through hole of the low thermal expansion metal plate and is exposed on the surface of the high thermal expansion metal foil, and the pressure contact strength is also significantly improved, and the high thermal expansion metal foil pressed against the low thermal expansion metal plate and heat high thermal expansion Combined with the pressing effect of the same material of the metal plate, a high pressing strength can be obtained with a smaller rolling force, the rolling ratio can be reduced, and the variation in the exposed area ratio is reduced.
In addition, if the high thermal expansion metal exposed on the surface of the high thermal expansion metal foil is the same material, the high thermal expansion metal plate exposed during pressure welding is heated to a temperature higher than the recrystallization temperature, so it can be integrated with the high thermal expansion metal foil. Very good surface properties.

The heat conductive material according to the present invention is used for laminating a low thermal expansion metal plate having a high thermal expansion metal foil pressed against at least one surface on one or both surfaces of the high thermal expansion metal plate. The through holes in the thickness direction are arranged on the entire surface or partially in the required interval and pattern, for example, the hole size, shape, arrangement pattern, etc. of the through holes are variously changed, and the through holes are penetrated or penetrated in the thickness direction in consideration of deformation during rolling. By selecting and combining means such as selecting a thickness ratio of the metal plate of the core material and / or a surface area ratio of the high thermal expansion metal and the low thermal expansion metal exposed on the surface of the low thermal expansion metal plate, The coefficient of thermal expansion and the thermal conductivity can be set according to the application and purpose for the whole or part of the material. For example, required metals, ceramics, semiconductors such as Si, plastics, etc. Achieving consistency with the thermal expansion coefficient of the counterpart material of the scan or the like, and a material having the required thermal conductivity.

In the present invention, since the high thermal expansion metal plate is press-fitted into the through-hole of the low thermal expansion metal plate by pressure welding, it is rich in the extensibility of Cu, Cu alloy, Al, Al alloy and the like. It is preferable to use a material having high thermal conductivity. In addition, the low thermal expansion metal plate is made of an extensible Mo, 30 to 50 wt% Ni containing Ni.
i-Fe alloy, 25 to 35 wt% Ni, 4 to 20 w
A Ni-Co-Fe-based alloy containing t% Co, W, or the like can be used. In the outermost layer of high thermal expansion metal foil,
Materials such as Cu, Cu alloy, Al, and Al alloy can be selected, and the same material or a different material as the core material of the high thermal expansion metal plate may be appropriately selected in consideration of the application and the material of the thin film layer to be adhered.

Further, depending on the application, Cu, Al, Ni, Sn, etc. are plated, vapor-deposited, ion-plated, etc. in order to improve brazing properties and corrosion resistance, or to improve the adhesion of Au and Ag plating. , CVD (che
In addition to applying by a known coating technique such as physical vapor deposition, solder,
It can be coated with an Ag brazing material, ceramics, glass layer, or the like, or can be applied at a required position.

The through-holes in the thickness direction of the low-thermal-expansion metal plate with the high-thermal-expansion metal foil pressed against the surface can be formed by mechanical processing such as press punching or chemical processing such as etching. A smaller width is advantageous in reducing the variation in products, and is usually 3 mm or less, preferably 1 mm.
The following, more preferably 0.5 mm or less, the cross-section of the through-hole shape is also a circular cross-section, polygonal, etc., the vertical cross-section is straight,
Various shapes such as a taper can be adopted, and in the case of the taper shape, press-fitting into the through hole can be facilitated and bonding strength can be increased. Further, the through hole in the thickness direction of the low thermal expansion metal plate may be a required through hole to be filled with the high thermal expansion metal plate after pressing and rolling. It is possible to make various choices so as to make the above-mentioned through-hole arrangement by penetrating in the required direction or making a cut just before penetration, or by changing the cut direction and various cut shapes from both sides of the metal plate, The shape of the cut is also-
Various shapes such as + <can be adopted, and a wedge-shaped cut such as a triangular pyramid can be formed in a required direction of the plate thickness. In the present invention, the rolling reduction is required to be about 60% when cold, but in the case of the present invention, the bonding between the high thermal expansion metals is extremely favorable in crystallography and can be reduced to about 20%. A rolling reduction of 30 to 50% is preferred.

Disclosure of the Invention Based on the Drawings The heat conducting material according to the present invention and the method for manufacturing the same will be described below in detail with reference to the drawings. The heat conductive material of the present invention shown in FIG. 1 is an example in which a copper plate is used as a high thermal expansion metal plate and a Kovar (Fe—Co—Ni alloy) plate is used as a low thermal expansion metal plate. A high-expansion metal foil layer 3 is provided on both sides, and a Kovar plate 2 having a large number of through holes 4 in the thickness direction is pressed.

High thermal expansion metal foil layer 3 pressed against both sides of copper plate 1
The Kovar plate 2 having a through hole 4 having the same dimensions in the plate thickness direction and a circular copper exposed surface 5 is arranged on the high thermal expansion metal foil layer 3, but the high thermal expansion metal foil layer 3 Are made of the same material, the copper exposed surface 5 is diffused and integrated so as to be indistinguishable. Further, here, the through holes 4 having the same size are formed in the thickness direction of the plate, but the through holes 4 may be tapered so that the hole sizes are different on the front and back, and may be arranged so that the adjacent holes have a combination of the sizes of the hole sizes. it can.

The thickness and the exposed copper surface 5 of the Kovar plate 2 pressed against both surfaces of the copper plate 1 via the high thermal expansion metal foil layer 3
By selecting the ratio, dispersion state, and the like, the thermal characteristics of each main surface can be approximated to the required characteristics. Further, the outermost high thermal expansion metal foil layer 3 may be formed of Cu, Cu alloy, Al, Al
Since an alloy or the like is selected, it is possible to obtain effects of uniform heat reception, a thermal diffusion effect, a bonding property with a counterpart material, and an improvement in adherence of a thin film.

In order to manufacture the above-mentioned heat conductive material using the copper plate, the Kovar plate and the copper foil, first, as shown in FIG. After the required length has been stocked by the looper device, punching is further performed by a press machine 8. For example, a large number of small holes are drilled to form a mesh, and after annealing, surface treatment is performed. And wind it up on a coil. After being pressed by the pressure roller 7, it can be wound once on a coil, then rewound again and fed to the press machine 8. Next, as shown in FIG. 3, the copper sheet 1 coil having the required size and thickness is rewound, heated to a temperature higher than the recrystallization temperature by the heating device 10, and rewound from above and below. 9 are stacked and pressed by the pressing roller 7.

In order to heat the copper plate 1 to a temperature higher than the recrystallization temperature at the time of press-contact with the three-layer punched material 9, 9, the copper plate 1 is fitted into the through hole of the Kovar plate 2 with a small rolling force and the copper of the Kovar plate 2 is pressed. Exposed on the surface of the foil 6, the copper foil 6 and the copper plate 1 between the copper plate 1 and the Kovar plate 2 and the copper foil 6 of the outermost layer and the copper plate 1 are diffused and integrated with each other. The strength is obtained, the deformation of the shape of the through-hole provided in the Kovar plate 2 is small, and the thermal expansion is different without changing the exposed area ratio of the exposed copper plate 1 and Kovar plate 2 on the surface of the Kovar plate 2 selected in advance. A predetermined coefficient of thermal expansion and thermal conductivity can be obtained without causing anisotropy.

In the above pressure welding, the heating atmosphere and the pressure welding atmosphere of the high thermal expansion metal material are preferably non-oxidizing atmospheres, such as N ₂ , Ar, H ₂ or a mixed gas atmosphere thereof, ammonia decomposition gas, and propane combustion. Gas (DX)
Gas or the like can be used. Further, the heating device is appropriately selected according to the material of the high thermal expansion metal material to be used, but a tubular furnace, a light beam heating device, a laser heating device, a high frequency heating device, a plasma heating device, or the like can be employed. The heating temperature of the high thermal expansion metal material is appropriately selected from a temperature range not lower than the melting point and higher than the recrystallization temperature of the selected material.
In the case of a copper alloy material, it is 950 to 1050 ° C, in the case of Al and an Al alloy material, it is 550 to 650 ° C, and in the case of Ag and an Ag alloy material, it is 800 to 900 ° C.

As shown in FIG. 4, instead of the three-layer punching material 9 in which the copper foil 6 is pressed against both surfaces of the Kovar plate 2,
After the copper foil 6 is pressed against the upper surface of the Kovar plate 2 by the pressing roll 7 and the required length is stocked by the looper device,
Punching is performed by a press machine 8 and the obtained two-layer punched material 11 is brought into contact with the Kovar plate 2 of the two-layer punched material 11 on both surfaces of the copper plate 1 heated to a recrystallization temperature or higher in the same manner as in FIG. Then, pressure welding is performed to produce the heat conductive material according to the present invention. After being pressed by the pressure roller 7, it can be wound once on a coil, then rewound again and fed to the press machine 8. In addition, the above-mentioned heat conductive material using the punched two-layer material 11 presses the Kovar plate 2 against both surfaces of the copper plate 1, and thus has the same press-contact strength as the one using the three-layer material 9 that is pressed between copper materials. In order to obtain, it is desirable to perform low-temperature annealing after the pressure welding. Further, since the outermost copper foil 6 of the heat conductive material is press-contacted to the Kovar plate 2 in advance, the advantage that there are few defects such as peeling is that the material is a punched three-layer material 9 and a punched material 2.
The same applies to any of the layer materials 11.

[0032]

EXAMPLE 1 Kovar plate (29N) having a thickness of 0.5 mm and a width of 30 mm was used.
An i-16Co-Fe alloy) was annealed at 900 ° C. and wire brushed. Then, a Cu foil having a thickness of 0.2 mm and a width of 30 mm was pressed against one surface thereof to obtain a Cu foil having a thickness of 60 μm.
m, a two-layer material with a total thickness of 0.28 mm and a hole diameter of 1.0 m
m, rolling direction hole spacing 2.0 mm, width direction hole spacing 2.0 m
Many perforations were made at m. In addition, 30-2 of Kovar plate
The average coefficient of thermal expansion at 00 ° C. is 5.2 × 10 ⁻⁶ /
° C.

Cu having a thickness of 0.35 mm and a width of 30 mm
After wire brushing the plate, heat it to 900 ° C,
The Cu plate is pressed against the Kovar surface side of the two-layer material by a pressure welding machine, and copper penetrates into the through-holes of the Cu / Kovar composite plate, and the copper plate surface is partially located at a required position of the outermost copper foil. An exposed and integrated three-layer material having a thickness of 0.25 mm was obtained. The rolling reduction was 60%. The exposed Cu surface on the main surface of the obtained heat conductive material was substantially circular in the rolling direction, the hole interval was 2.0 mm in the rolling direction, and the ratio of the exposed Cu surface to the Kovar plate was 35%. 30-200 ° C for Cu plate
The average coefficient of thermal expansion was 17.2 × 10 ⁻⁶ / ° C. The thermal conductivity in the thickness direction of the obtained material is 250 w /
m · K and the coefficient of thermal expansion on each main surface are 9 × 10 ⁻⁶ /
° C.

Example 2 A Kovar plate (29N) having a thickness of 0.5 mm and a width of 30 mm was used.
An i-16Co-Fe alloy) was annealed at 900 ° C. and wire brushed. Then, a Cu foil having a thickness of 0.2 mm on one side, a thickness of 0.05 mm on the other side, and a width of 30 mm was pressed to obtain a Cu foil thickness of 30 μm. A 3-layer material with a total thickness of 0.29 mm, a hole diameter of 1.0 mm, and a hole interval of 2.0 m in the rolling direction
A large number of perforations were made at a distance of 2.0 mm in the width direction between holes.

Cu having a thickness of 0.35 mm and a width of 30 mm
After wire brushing the plate, heat it to 900 ° C,
The Cu plate is pressed against the thinner side of the three-layered material by a pressure welding machine, and copper penetrates into the through-holes of the Cu / Kovar composite plate, and the surface of the copper plate is positioned at a required position of the outermost copper foil. A partially exposed, three-layer material having a plate thickness of 0.25 mm was obtained. The rolling reduction was 62%. The exposed surface of Cu on the main surface of the obtained heat conductive material was substantially circular in the rolling direction, the hole interval was 2.0 mm in the rolling direction, and the C
The ratio of the u-exposed surface was 35%. The thermal conductivity in the thickness direction of the obtained material was 250 w / m · K, and the coefficient of thermal expansion on each main surface was 9 × 10 ⁻⁶ / ° C.

Example 3 A Kovar plate (29N) having a thickness of 0.3 mm and a width of 30 mm was used.
i-16Co-Fe alloy), annealed at 900 ° C and wire brushed, then 0.05mm on both sides
A 30 mm thick Cu foil is pressed into contact with a 30 μm thick Cu foil.
m, a three-layer material with a total thickness of 0.25 mm, a hole diameter of 1.0 m
m, rolling direction hole spacing 2.0 mm, width direction hole spacing 2.0 m
Many perforations were made at m.

A Cu plate having a thickness of 0.5 mm and a width of 30 mm was subjected to wire brushing, heated to 800 ° C., and the above three-layered material was pressed against both surfaces thereof by a pressing machine as shown in FIG. Copper penetrated into the through-holes, and the surface of the copper plate was partially exposed at a required position of the outermost copper foil to obtain an integrated three-layer material having a plate thickness of 0.4 mm. The rolling reduction was 60%. The exposed surface of Cu on the main surface of the obtained heat conductive material was substantially circular in the rolling direction, and the hole interval was 2.0 mm in the rolling direction.
And the ratio of the Cu-exposed surface to the Kovar plate is 35%.
Met. The thermal conductivity of the obtained material in the thickness direction is 230.
w / m · K and the coefficient of thermal expansion on each main surface is 8 × 10
⁻⁶ / ° C. In this heat conductive material, the thickness (t ₁ ) of the Cu plate is 0.15 mm, the thickness (t ₂ ) of the Kovar plate is 0.115 mm, and the thickness (t ₃ ) of the Cu foil on the surface is 0.01 mm, respectively. (See FIG. 1).

A heat conductive material having a thickness of 0.4 mm was cut to a required size, and two sheets were laminated to form a heat dissipation substrate. When a ceramic package was produced using the above-mentioned heat dissipation substrate, it was confirmed that good heat dissipation was obtained and thermal matching was excellent.

Further, a heat conductive material having a thickness of 0.4 mm
After annealing in a hydrogen atmosphere at 000 ° C. for 5 minutes, it was worked to a sheet thickness of 0.15 mm by cold rolling. In the obtained heat conductive material, the thickness (t ₁ ) of the Cu plate constituting the core is 0.068.
mm and the thickness (t ₂ ) of the Kovar plate are 0.038, respectively.
mm, and the thickness (t ₃ ) of the Cu foil on the surface is 0.00
3 mm. After that, it was processed into a lead frame by a known method, and a semiconductor package was fabricated.Without peeling of the bonding interface between the chip and the island, cracking of the sealing resin, etc. did not occur, and a conventional copper alloy was used. Good heat dissipation similar to that of a lead frame was obtained.

[0040]

The heat conductive material according to the present invention is a three-layer material or a two-layer material having a large number of through-holes in the thickness direction after a high-thermal-expansion metal foil is pressed and integrated on both or one side of a low-thermal-expansion metal plate. The layer material is pressed against one or both surfaces of a high thermal expansion metal plate heated to room temperature or a recrystallization temperature or higher to expose and integrate the high thermal expansion metal from the through hole to the surface of the high thermal expansion metal foil, thereby obtaining a bonding strength. The coefficient of thermal expansion and the thermal conductivity can be changed arbitrarily without changing the thickness ratio or through-hole area ratio of these selected metal plates, and semiconductors such as metals, ceramics, and Si, plastics The balance of the coefficient of thermal expansion with the material to be adhered to, such as metal, and good thermal conductivity can be achieved.Furthermore, uniform heat reception and improvement of the heat diffusion effect are achieved. To adhere to Are, the optimal heat transfer material to the radiating substrate and the material for the lead frame for semiconductor chip mounting. Further, since only one press-contact, which is a factor of the change in the thickness ratio of the metal plate and the area ratio of the through-hole, is required, the process is simplified and the heat conductive material can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective explanatory view of a heat conductive material according to the present invention.

FIG. 2 is a perspective explanatory view showing an example of equipment for producing a heat conductive material according to the present invention.

FIG. 3 is a perspective explanatory view showing an example of equipment for producing a heat conductive material according to the present invention.

FIG. 4 is an explanatory perspective view showing an example of equipment for manufacturing another heat conductive material according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Copper plate 2 Kovar plate 3 High thermal expansion metal foil layer 4 Through-hole 5 Copper exposure surface 6 Copper foil 7 Pressing roll 8 Press machine 9 Punching three-layer material 10 Heating device 11 Punching two-layer material

Claims (4)

(57) [Claims] 1. A low thermal expansion metal plate having one or both surfaces
High thermal expansion metal foil integrated on one side of thermal expansion metal plate and thickness
A two-layer material having a large number of through holes in the
While laminating and integrating so that the foil is placed on the outer surface,
Thermally conductive material, wherein a part of the through hole formed in the high thermal expansion metal Hakugai surface of the high thermal expansion metal plate is exposed to intrusion. 2. A low thermal expansion metal plate having one or both surfaces
High thermal expansion metal foil integrated on both sides of thermal expansion metal plate and thickness
When three layers with many through holes in the direction are laminated and integrated
Both the through holes formed on the outer surface of the high thermal expansion metal foil
Note that part of the high thermal expansion metal plate
Characteristic heat conductive material. 3. A two-layer material provided with a large number of through holes in a thickness direction after a high-thermal-expansion metal foil is pressed into contact with one side of a low-thermal-expansion metal plate, and then heated to room temperature or a recrystallization temperature or higher. On one or both sides of the expansion metal plate, the high thermal expansion metal
When laminating and integrating by pressing so that the foil is placed on the outer surface
In both cases, a method of manufacturing a heat conductive material is characterized in that a part of the high thermal expansion metal plate is made to enter and expose through the through hole in which the high thermal expansion metal foil is formed on the outer surface . 4. A three-layer material provided with a large number of through holes in a thickness direction after a high-thermal-expansion metal foil is pressed into contact with both surfaces of a low-thermal-expansion metal plate, and then heated to room temperature or a recrystallization temperature or higher. Press-contact one or both sides of the expanded metal plate to laminate and integrate
As well as reduction method of thermally conductive material, characterized in that the high thermal expansion metal foil exposed infested part of the high thermal expansion metal plate from <br/> the through holes formed on the outer surface.