Composite material

 

The invention relates to powder metallurgy, in particular to obtain a composite material that can be used, for example, in semiconductor devices. Proposed composite material consisting of metal and inorganic particles with less than metal, the coefficient of thermal expansion, which are dispersed in the metal so that at least 95% of the particles on the area occupied by them in cross-section, form an interconnected aggregates of complex shape. The material contains no more than 100 individual inorganic particles 100 μm2cross-sectional area of the material. In the range of 20 - 150oWith the coefficient of thermal expansion of the material increases on average (0,025-0,03 5)X10-6/oWith the change in the coefficient of thermal conductivity at 20oWith 1 W/(mK). The proposed material, for example, may consist of copper and particles of copper oxide. The technical result of the invention is the production of a material with a low coefficient of thermal expansion and high thermal conductivity, which is easily processed by pressure. 4 S. p. f-crystals, 21 ill., table 4.

The invention of otnositelnosti, the method of its production and to its use in semiconductor devices.

When you create powerful electronic devices typically use a powerful electronic devices that convert electrical power and electrical energy and carrying out the associated process control, high-power electronic devices operating in relay mode, and built on such devices system power conversion.

The conversion of electric power associated with the use of various semiconductor devices that act as switches. For such semiconductor devices include, in particular, the rectifier diodes (p-n - junction, pass current in only one direction) and thyristors, bipolar transistors and MOS transistors (field-effect transistors with insulated gate) (with a combination of p-n junctions). Such semiconductor devices are also newly developed bipolar transistors with insulated gate (IGBT) and a lockable thyristors, switching when applying to the shutter control signal.

Such power semiconductor devices upon excitation emit heat. The quantity of the emitted semiconductor device heat increases when egrave under the action they radiate heat and prolonging their service are usually used radiators, which prevent unacceptable temperature increase of the semiconductor device and adjacent the various items of electronic equipment. For the manufacture of radiators, typically use copper, which has low cost and has high conductivity (393 W/m). However, copper cannot be used for the manufacture of heat sinks for high-power semiconductor devices, as it is, having a high coefficient of thermal expansion equal to h-6/oWith poorly connected by soldering with silicon, the coefficient of thermal expansion which is equal to 4,2x10-6/oC. One possible way around this problem is to use heat sinks made of molybdenum or tungsten, which by its coefficient of thermal expansion do not differ from silicon or made of molybdenum or tungsten gaskets installed between the radiator made of copper and the semiconductor element.

Power semiconductor elements differ from conventional electronic semiconductor elements. As an example of the latter can be called an integrated circuit (IC) consisting of various electronic circuits combined in about tristessa on the memory elements, logic gates, microprocessors, etc. the Problem that has hindered the wide use recently created electronic semiconductor elements, associated with the radiation of heat, the amount of which increases with the degree of integration and performance of IP. This problem becomes even more acute due to the fact that some electronic semiconductor elements are usually collected in the module in sealed enclosures that protect them from premature failure under the influence of environmental conditions. The most common IC packages are ceramic case (in which every prisoner in the case of a semiconductor element attached to the ceramics by the method of connection of crystal and plastic body (when semiconductor elements are filled into plastic). As a semiconductor device having high reliability and great performance, you can call the newly established multi-chip module (MCM) consisting of a large number of semiconductor elements collected in the chip on a common substrate.

In the manufacture of integrated circuits with a plastic case findings concluded in the case of semiconductor ele is ement, and its lead frame are filled into plastic (compound). To solve the problems associated with the intense heat, were recently developed IP, in which the dissipation is carried out by using either enclosed in a housing leadframe, or by using an appropriate heat sink. Carrying out the necessary dissipation lead frame or the heat sink is usually made of copper having high thermal conductivity. However, due to different coefficients of thermal expansion of copper and silicon in the work of the IP, you can expect a different kind of trouble.

Unlike IP with plastic housing IP with ceramic housings semiconductor element is located on the ceramic substrate, made in the form of circuit boards, and is sealed metal or ceramic lid. The reverse side of the ceramic substrate coated with a composite material or of copper and molybdenum (cu-Mo) or copper-tungsten (Cu-W), or cobaltocene alloy (Kovar), which acts as a heat sink. To create a cheap IP requires a ceramic material having a low coefficient of thermal expansion, high thermal conductivity and good handling is key, made in the form of circuit boards, several collected therein semiconductor elements (in the form of a planar crystal), ceramic casing, within which is located the substrate've put together of the semiconductor elements, and hermetically closing the case cover. When the need for heat dissipation is used located on the body of the radiator or made on it by the fin. The metal substrate is made of copper or aluminum. The advantage of this is made of copper or aluminum substrate is its high thermal conductivity, and the disadvantage is the high coefficient of thermal expansion significantly different from the coefficient of thermal expansion of the semiconductor element. Therefore, to improve the reliability of the substrate multichip modules are made of silicon or aluminum nitride (AlN). The radiator, which should be attached to the ceramic substrate must be made of a material with high thermal conductivity and low coefficient of thermal expansion that these indicators could match the material of the module housing.

As noted above, all semiconductor devices during operation is bhodemon to use a heat sink with high thermal conductivity. To match the radiator semiconductor element to which it is attached directly or through an insulating layer, the material from which it is made, must possess not only a high thermal conductivity and low coefficient of thermal expansion.

The most common semiconductor elements are manufactured on the basis of Si or GaAS, the coefficient of thermal expansion which varies from 2,6x10-6/oC to 3,6X10-6/oC and from 5,7x10-6/oC to 6,h-6/oC, respectively. The materials that the coefficient of thermal expansion match to the material of the semiconductor element include AlN, SiC, Mo, W and Cu-W. However, in the manufacture of radiators only from such materials cannot be achieved, so that the heat transfer coefficient and thermal conductivity of the heat sink can be changed depending on a specific need. In addition, such materials are difficult to be processed, and made of them the radiators are of high value. In lined with the patent application of Japan Ne 8-78578 proposed sintered alloy of copper and molybdenum (cu-Mo). In lined with the patent application of Japan Hei 9-181220 proposed sintered alloy of copper is Bida silicon (si-SiC). In lined with the patent application of Japan Hei 9-15773 proposed composite material consisting of aluminum and silicon carbide (Al-SiC). Such presently known materials by changing the ratio between the forming components of the heat transfer coefficient and thermal conductivity can be varied within fairly wide limits. These materials, however, badly treated by pressure, and therefore the production of these thin plates difficult and requires a large number of technological operations.

Based on the foregoing, the present invention was used to develop composite material, which would have a low coefficient of thermal expansion and high thermal conductivity and which can easily give in to the pressure treatment.

The first object of the present invention is a composite material consisting of metal and inorganic particles with less than metal, the coefficient of thermal expansion, wherein the inorganic particles dispersed in the metal so that at least 95% of the particles on the area occupied by them in cross-section, form a connected to the first material, consisting of metal and inorganic particles with less than metal, the coefficient of thermal expansion, characterized in that it contains not more than 100 individual inorganic particles 100 μm2cross-sectional area of the material, while the remaining particles dispersed in the metal, form interconnected aggregates of complex shape.

The third object of the present invention is a composite material consisting of metal and inorganic particles with less than metal, the coefficient of thermal expansion, wherein in the range from 20 to 150oWith its coefficient of thermal expansion increases on average (0,025-0,035)X10-6/oWith the change in the coefficient of thermal conductivity at 20oWith 1 (W/mIt).

The fourth object of the present invention is a composite material consisting of copper particles, copper oxide, characterized in that the particles of copper oxide dispersed in a copper so that at least 95% of the particles on the area occupied by them in cross-section, form an interconnected aggregates of complex shape.

Proposed in the present invention, the composite material is sitelines because of its high melting point and high strength. Inorganic particles are preferably particles that remain quite soft and stable after sintering and in which the average coefficient of thermal expansion in the temperature range from 20 to 150oWith equal to or less than 5,0x10-6/oC, preferably equal to or less than 3,5x10-6/oC and a hardness equal to or less than 300 units Vickers. (These particle differ from conventional particles such as particles of silicon carbide (SiC) and aluminum oxide (Al2O3), which by their hardness significantly different from the matrix metal). Composite material with soft inorganic particles after sintering well handled pressure (hot or cold). Prokalivaemosti such a composite material allows for short processing time to make him quite thin plate. The resulting composite material is due to the presence of dispersed in the metal inorganic particles high strength. The examples contained in the proposed invention the composite material of inorganic particles are particles of copper oxide, tin oxide, lead oxide and oxide nick is certain of the above materials coefficient of thermal expansion.

Proposed in the present invention, the composite material preferably contains a reinforcing its solid fine ceramic particles such as silicon carbide (SiC) or aluminum oxide (Al2O3), with a hardness greater than 1000 units Vickers, and an average diameter equal to or less than 3 μm, the content of which the material does not exceed 5% vol.

The framework proposed in this invention a composite material is preferably an alloy of copper (cu), consisting of 20-80 vol.% oxide monovalent copper (cu2About) and containing copper phase (C) and the phase of the oxide monovalent copper (cu2O) forming a dispersed structure.

The coefficient of thermal expansion of the composite material in the temperature range from room temperature up to 300oWith should preferably be from 5x10-6to h-6/oC, and the conductivity of from 30 to 325 W/(mIt).

In consisting of copper and copper oxide composite material should preferably contain from 20 to 80 vol.% oxide monovalent copper (cu2About), the rest is copper. Copper phase (C) and the phase of the oxide monovalent copper (cu2O) must be oriented structure. Coefficient C is preferably from 5x10-6to 14x10-6/oC, and the conductivity of from 30 to 325 W/(mK). thermal conductivity of the proposed composite material in the direction of orientation should at least two times greater than its thermal conductivity in the direction perpendicular to the direction of orientation.

Proposed in the present invention a composite material obtained by mixing copper powder with powder of oxide of monovalent copper, subsequent pressing of the powder mixture, sintering the pressed billets at 800-1050oAnd the processing pressure in a cold or hot condition. (The copper powder is an example of metal, which consists of a composite material, and the powder of the oxide of monovalent copper is an example of the constituent inorganic particles).

Proposed in the present invention the copper composite material is obtained from peremeshannyj each other powder of the oxide of the divalent copper (CuO) and copper powder (si), which necessarily contains certain impurities. The quantity of oxide of divalent copper in this material is from 10.8 to 48.8 about. %. The process of manufacturing such components>With subsequent curing the pressed workpiece and the formation of si2In the reaction between SIO and si, pressing the resulting material in hot or cold (for pressure) and annealing.

Proposed in the present invention a composite material consists of C and C2Oh, while copper has a high thermal expansion coefficient equal to 17,6X10-6/oWith, and a high coefficient of thermal conductivity equal to 391 W/(mK), and oxides of monovalent copper has a low coefficient of thermal expansion equal to 2,h-6/oWith, and low coefficient of thermal conductivity equal to 12 W/(mK). By sintering powder of this material make plate heatsink designed to cool the semiconductor devices. In a powder molded product, the content of C and C2About 20 to 80 vol.%. The coefficient of thermal expansion of the product ranges from 5x10-6to h-6/oC, and the coefficient 30-325 W/(mK) in the temperature range from room temperature up to 300oC. Composite material in which the content of si2About more than 20 vol.%, and intim radiators. A composite material in which the content of si2About 80% or less, has a sufficiently high thermal conductivity and structural strength.

Proposed in the present invention a composite material was obtained essentially by the methods of powder metallurgy. Copper composite material is obtained from si powder and a powder of si2O or CuO powder. These powders (raw materials) are mixed with each other in a certain proportion, then the obtained powder mixture was cold pressed into a corresponding mold and the resulting billet is sintered. If necessary, a powder molded product is subjected to a pressure treatment in hot or cold condition.

The raw materials are mixed together in the mixer, V-type strainer, ball mill or mills with mechanical melting of the particles. The particle size of the original powder materials affect the mode, pressing and distribution of si2O obtained after sintering the material. Therefore, the copper powder particles should have a diameter not exceeding 100 μm, and the powder particles of si2Oh and SIO should have a diameter of less 10 μm and preferably equal to 1-2 microns.

Peremeny powder C2About the pressure should preferably be increased.

Obtained from a mixture of powders of the workpiece is sintered in an argon atmosphere at normal pressure or subjected to hot isostatic pressing or pressed in a hot state at a certain pressure. The sintering process should last for approximately 3 hours and take place at a temperature of 800-1050oC. the Temperature at which the sintering of powders, increase proportionally with the increase of the number contained in the mixed oxide powder monovalent copper (cu2About). The sintering temperature varies depending on the type of matrix metal. When used as a matrix metal of copper during sintering temperature equal to or less 800oWith, a powder molded product will have a low density. On the other hand, when the sintering temperature equal to or greater than 1050oSince, in the sintered powder is eutectic interaction between C and C2Oh, accompanied by their partial melting. Therefore, the optimal sintering temperature is a temperature lying in the range from 900oWith up to 1000oC.

Proposed in the present invention IU the second hardness. Therefore, such a composite material, if necessary, after sintering can handle pressure in a cold or hot state, for example by rolling or hot pressing. Under this treatment thermal conductivity of the composite material becomes anisotropic, which gives it strength and creates the preconditions for its use in cases, when the process of heat transfer by conduction should be strictly directed.

In accordance with the present invention the raw material from which to obtain its proposed composite material, which may be bivalent copper oxide (CuO). In this case, the powder of CuO are mixed with powder C and the resulting mixture of powders are compressed. The resulting extrusion billet is sintered with the simultaneous oxidation of si. The result: an item consisting of a copper matrix and dispergirovannoyj it phase si2O. At high temperatures as a result of interaction between SIO and si according to the following equation (1) is formed (with heat resistant) oxide monovalent copper (cu2): 2Cu+CuO-->Cu+Cu2O (1) To achieve equilibrium in the process of reaction, opisyoWith the necessary equilibrium is approximately three hours.

Particles of si2On sintered mass should be possible in small sizes, because of their diameter substantially depends on the density, strength and the ability to process the pressure of the resulting composite material. The diameter of the particles depends significantly on the method of mixing the original powders. The increase was spent in hashing power results in less coagulation of particles, which consist of mixed powders. When the optimal mode of mixing powders, you can get contained in the obtained after sintering the mass of the particle C2About had small sizes.

In accordance with the present invention the size of the particles forming in the composite material phase si2Oh, is determined depending on what equipment is used for mixing the original powders. When mixing the powders in the mixer, V-type, or in a ball mill filled with steel balls (i.e., at small spent hashing power) 50% vol. (or more) of the particles will have a diameter of 50 μm or less, and under stirring with a mechanical melting of the hour is wny 10 μm or less, the diameter of the remaining particles will lie in the range from 50 to 200 microns. When the particle size of equal to or greater 200 μm, the obtained composite material will have a high porosity, and therefore the processing pressure is associated with certain problems. The obtained composite material in which the content of phase C2About more than 50 vol.%, has low thermal conductivity and has unstable properties and therefore cannot be used for the manufacture of plate heat sinks for semiconductor devices. The preferred structure is a structure consisting of a copper phase (C) and uniformly distributed therein phase oxide monovalent copper (cu2O) (particle size which does not exceed 50 μm). Particles of si2About have a very irregular shape and before sintering are connected to each other; therefore, their sizes can be determined under a microscope only at very high magnification. Preferably, the size of the forming phase si2Of particles does not exceed 10 microns.

Attached to the description of the drawings shown in Fig. 1 is a micrograph showing the microstructure of the sintered mass (consisting of C and 55% vol. C2O) proposed in this invention is represented by the microstructure of the sintered mass (consisting of C and 55% vol. C2O) proposed in the present invention a composite material obtained according to the technology described in example 2, Fig. 3 is a micrograph showing the microstructure of the sintered mass (consisting of si and 40% vol. C2O) proposed in the present invention a composite material obtained according to the technology described in example 3, Fig.4 is a micrograph, which is in a plane parallel to the direction of deformation of the particles during hot stamping, shows the microstructure obtained by hot stamping technology, described in example 4, provided in the present invention a composite material (consisting of C and 55% vol. C2O), Fig. 5 is a micrograph showing the microstructure of the sintered mass (consisting of si and 32,2% vol. SiO) proposed in the present invention a composite material obtained according to the technology described in example 5 (sample 14), Fig.6 is a graph of the dependence of the coefficient of thermal expansion composite material from its coefficient of thermal conductivity, Fig. 7 is a top view made in accordance with the present invention and described in example 6 IGBT-module IGBT insulated gate),
in Fig.8 - p is ü operations, performed when manufacturing the IGBT module, described in example 6,
in Fig. 10 is a graph showing the deformation (deflection) of the Foundation in accordance with the present invention and described in example 6, the IGBT module at each stage of its manufacturing,
in Fig. 11 is a top view and cross section of a power Converter with made in accordance with the present invention and described in example 6 IGBT-module
in Fig. 12A and 12B is graphs showing the deformation of the power Converter without made in accordance with the present invention and described in example 6 IGBT-module
in Fig. 13A and 13B is graphs showing the deformation of the power Converter if it is made in accordance with the present invention and described in example 6 IGBT-module
in Fig.14 is a cross-section described in example 7 of the plastic housing of a semiconductor device with a built-in plate heat sink made in accordance with the present invention,
in Fig.15 is a cross-section described in example 7 of the plastic housing of the semiconductor device located outside of the radiator plate made in accordance with nastoiashshem invention housing a semiconductor device,
in Fig. 17 is a transverse section of the ceramic housing of a semiconductor device described in example 8 and is made in accordance with the present invention a heat sink with heat-dissipating fins,
in Fig. 18 is a transverse incision is made in accordance with the present invention and described in example 9 of a semiconductor device,
in Fig.19 is another cross-section made in accordance with the present invention and described in example 9 of a semiconductor device,
in Fig. 20 is a transverse incision is made in accordance with the present invention and described in example 10 multichip module (MCM) and
in Fig. 21 is a cross section proposed in the present invention the electrostatic attractor.

The preferred embodiment of the invention
Example 1
In this example, as the source of powder materials used electrolytic copper powder (with a particle diameter of 75 μm and a powder of si2About (with a particle diameter of 1-2 μm and an indicator of purity equal to 3N). These powders were mixed together in different proportions shown in table 1. The resulting mixture (1400 g) are thoroughly mixed for 10 hours in a ball mill filled steel is radnom able extruded at different (depending on the content of si2A) the pressure in the interval from 400 to 1000 kg/see the result of powder received a round billet with a diameter of 150 mm and a height of 17-19 mm, Then these blanks were specaly in argon atmosphere. Obtained by sintering the parts were subjected to chemical analysis, investigated their structure and measured the coefficient of thermal expansion, thermal conductivity and Vickers hardness. It should be noted that the sintering of the compacted powder was carried out for 3 h at different dependent on the content of si2The temperature in the range from 900 to 1000oC. the Coefficient of thermal expansion was measured at different temperatures in the range from room temperature up to 300oWith using this device for TMA (thermomechanical analysis). thermal conductivity of the material obtained was measured by means of laser flash. Measured results are shown in table 1. The microstructure of the sintered parts (sample 4) shown in Fig.1.

The results of chemical analysis confirms the conformity of the chemical composition obtained after sintering the details of the composition of the initial mixture of powders. From table 1 it follows that the coefficient of thermal expansion of the material obtained and the conductivity change in a broad population of sintered composite material, which according to its thermal characteristics meets the requirements of lamellar radiators.

In the form shown in Fig.1 micronance (filmed at 300-fold increase) of the microstructure of the material obtained shows that the contained particle phase Cu2Oh, the size of which does not exceed 50 μm uniformly dispersed in the phase of si. (During mixing of powders is the coagulation of particles of si2Oh, and during sintering is a slight increase in their size). On micronance white colored phase C, and black - phase si2O.

As shown in Fig.1, 99% (or more) cross-sectional area dispersed in the copper phase particles C2About have an irregular shape.

The hardness of the phase C and phase C2O (Nv) respectively 210-230 and 75-80. Obtained after sintering detail lends itself well to machining (turning and drilling), and so if necessary it can be given any desired shape.

Example 2
In this example, the proposed invention is a composite material was obtained by the same technology as in example 1, except that the powders were mixed in the mixer V-shaped type. Obtained after sintering Pcture, the coefficient of thermal expansion and coefficient of thermal conductivity.

In Fig. 2 shows a micrograph (taken at 300-fold increase), obtained after sintering parts, consisting of C and C2(55 about. %). On the basis of microneme can be concluded that the microstructure of the resulting material contains particles of si2Oh, which differ significantly from each other in their size. Large particles C2About formed due to coagulation of small particles in the process of mixing the powders in the mixer V-shaped type. The coefficient of thermal expansion and coefficient of thermal conductivity obtained in this example, after sintering powders item practically does not differ from the same chemical composition details, in which the phase of the C2Uniformly dispersed in the phase of si. However, this material is characterized by a great variability of the resulting measurement values, which differ from each other depending on where the sample is measured. Analogously to example 1 (Fig.1) dispersed in the copper phase of the material particles of si2About are mostly irregular in shape and larger than in example 1 units.

Example 32. In the end of the powder obtained has the appropriate dimensions of the round billet. Then, the workpiece was specaly in argon atmosphere for 2 hours. The resulting sintering details have investigated the structure and measured the coefficient of thermal expansion and coefficient of thermal conductivity (the same as in example 1, by the way). In addition, the resulting material was investigated by x-ray diffractometer.

In the form shown in Fig.3 micronance (filmed at 1000-fold magnification) is clearly visible microstructure of the material obtained after sintering. Visible on this microniche particles C2Oh, the size of which (up to 10 μm) is smaller than the particle size of si2Oh, contained in the materials obtained in examples 1 and 2, are uniformly dispersed in MEK and be capable of rolling in a cold state. It should be noted that in this material, as the material shown in Fig.1, more than 95% of the dispersed therein particles of si2About have an irregular shape, however, some particles of si2About (about 20 square 100 µm) have a spherical shape.

For identification contained in the received after sintering the material of oxides conducted research on x-ray diffractometer. The results of these studies showed that the resulting material contains only monovalent oxide copper (Cu2O). From this it follows that in the sintering process, there was a complete transformation of oskido divalent copper (CuO) in the oxide monovalent copper (Cu2O). In the analysis of the chemical composition of the material was determined that he, as expected, consists of a copper (cu) and monovalent oxide of copper (cu2O) (40 vol%).

Obtained in this example, after sintering of the powder composite material according to the coefficient of thermal expansion and coefficient of thermal conductivity does not differ from those obtained after sintering powder material of the same composition, referred to in the following example 5.

Example 4
As starting materials in this example used the same powder is novecentos of copper (cu2O) (55 vol%). The resulting mixture (550 g) were thoroughly mixed in the mixer V-shaped type. Obtained after mixing, the powder was placed in the mold with a diameter of 80 mm and cold-extruded at a pressure of 600 kg/cm2. As a result of powder received a round billet with a diameter of 80 mm and a thickness of 22 mm, Then the workpiece within 3 hours specaly in an argon atmosphere at a temperature of 975oC. Obtained after sintering, the part was heated to 800oAnd hot extruded at 200-ton press (when the ratio of hot pressing volume 1.8). Pressed hot item was released and annealed at a temperature of 500oC. in the same manner as in example 1, was determined by the structure of the resulting composite material, its thermal expansion coefficient and thermal conductivity.

Not counting the edges of the small cracks in the rest obtained in the process of hot pressing, the product qualities are fully met all its requirements. The conclusion that can be drawn from this, is that proposed in the present invention, the composite material is a material with eliminate is OK (filmed at 300-fold increase) of the microstructure obtained by hot pressing products. This product and the copper phase (C), and phase C2About deformed and arranged in the direction of the efforts of hot pressing, it should be noted the absence of any defects or cracks. In this regard, it should also be noted that 95% (or more) dispersed in the copper particle phase si2About connected with each other and have an irregular shape. All of these particles are elongated in a certain direction under the action of a force generated when processing the sintered material pressure during hot pressing.

The details obtained after sintering of the powder, and the product obtained after hot pressing, by means of laser flash was determined coefficient of thermal conductivity (see table 2). Item received after sintering, by its thermal conductivity is almost isotropic. In contrast, the product obtained after hot pressing, has by this measure certain anisotropic. thermal conductivity of the material obtained in the direction L in which the orderly and copper phase (C), and phase C2A) more than two times greater than its thermal conductivity in the direction (the direction of the force generated during hot pressing), the perpendicular is irenew is almost homogeneous (isotropic) and in this respect similar material, described in example 1.

Example 5
In this example, as the source of powder materials used electrolytic copper powder (with a particle diameter of 74 μm) and CuO powder (with a particle diameter of 1-2 μm and an indicator of purity equal to 3N). These powders were mixed together in different proportions shown in table 3. The resulting mixture (1400 g) are thoroughly mixed for 10 hours in a ball mill, dry grinding, filled with steel balls. Obtained after mixing in a ball mill, dry grinding, the powder was placed in the mold with a diameter of 150 mm and cold-extruded at different (depending on the content of CuO) pressure in the range from 400 to 1000 kg/cm2. As a result of powder received billet, which was specaly in argon atmosphere. Obtained by sintering the parts were subjected to chemical analysis, investigated their structure and measured the coefficient of thermal expansion and coefficient of thermal conductivity. In addition, they investigated the x-ray diffractometer for the purpose of identification contained in the oxides. It should be noted that the sintering of the compacted powder was carried out for 3 hours at different dependent on the content of CuO temperature in the range from 900 d is 300oWith using this device for TMA. thermal conductivity of the material obtained was measured by means of laser flash. Measured results are shown in table 3.

For identification contained in the received after sintering the material of oxides conducted research on x-ray diffractometer. The results of these studies showed that the resulting material contains only monovalent oxide copper (Cu2O). From this it follows that in the sintering process, there was a complete transformation of bivalent copper oxide (CuO) in the monovalent oxide of copper (cu2O).

The microstructure of the sample 14 is shown in Fig.5. On Mironenko (filmed with a 300-fold magnification) can be judged that when the same chemical composition on the structure material of this sample does not differ from the material obtained in example 1. Phase C2About this material consists of si2Oh, which is formed of si and SIO with their oxidation, and C2Oh, which was formed by the decomposition of CuO. By its size and form of particles of si2Oh, contained in the received material, do not differ from the particle si2Oh, contained in the material of example 1.

As follows from table 3, the coefficient capoluongo from a powder of si2O. However, its conductivity greater thermal conductivity material obtained from a powder of si2On (when the content of si2About more than 50 vol.%). This is because the sintered material obtained from a powder of CuO, has more in comparison with material obtained from a powder of si2Oh, density.

In Fig.6 shows a graph of the relationship between the coefficient of thermal conductivity (x-axis) and the coefficient of thermal expansion (y axis) based on the data presented in table 3. Individual points corresponding to the different samples of the material lying between two straight lines described by the equations y = 0,031 x + 4,65 and y = 0,031 x + 5,95. Therefore, for this material in the temperature range from 20 to 250oWith the change of thermal expansion coefficient with the change in the coefficient of thermal conductivity at 20oWith 1 W/(mK) will on average be (0,025-0,035)X10-6/oC.

Example 6
This example describes a possible application of the proposed in the present invention the copper composite material. Specifically in this example, its use for the manufacture of plate heat sink for IGBTs (bipolar transistor with Yves top view showing the internal structure of the semiconductor block, consisting of 24 are grouped in modules of bipolar transistors with insulated gate. In Fig.8 shows a cross section of one of the modules such transistors. The module contains four IGBT element 101 and two diodes 102, which solder 201 is connected with the AlN substrate 103. AlN-substrate 103 consists of two sheets of copper foil 202 and 203 and AlN-card 204, which are connected to each other by a silver solder (not shown). In AlN substrate 103 is made of land for the emitter interconnects 104, manifold interconnects 105 and interconnects 106 gates. The IGBT element 101 and the diode 102 is soldered to manifold interconnect 105. Each element is connected to the emitter interconnect 104 of the metallic wire 107. On the site of the interconnect 106 gates is the resistor 108, which is a metal wire 107 is connected to the contact pad of the gate of the IGBT element 101. Six AlN-substrate placed on them by semiconductor elements solder 205 is connected with plate heat sink 109. Plate heat sink 109, the surface of which is covered with a layer of Ni, produced as described in examples 1-5 composite material containing Cu-Cu2O. AlN-substrate 103 are connected by solder 209 output 206. The output 206 and the plastic housing 207 clicks the water, reaching from the base 208 of the module, connected with located on each AlN-substrate two emitter pins 110, two control emitter pins 111, two collector pins 112 and one output 113 of the shutter. All pins of the module is sealed with silicone gel 212, which is injected into the housing through the cover 211 (which to this end has hole). After that, all the internal space of the housing is filled with poured into him thermosetting epoxy resin 213. The process of manufacturing the module ends. Plate heat sink 109 is attached to the aluminum base eight bolts that pass through eight existing holes 114. Holes 114 under the bolts are in a plate heat sink mechanically. The other eight bolts that pass through holes 115, the radiator is connected (in addition to glue 210) with housing 207 module.

Table 4 shows data comparing thermal expansion and thermal conductivity is usually used for manufacturing the base semiconductor module materials and copper composite material proposed in the present invention (containing 30 vol.% Cu2O). Mark is the Rial (Cu-Cu2O), has a smaller thermal expansion coefficient than the module in which the base is made of plain copper. The presence of solder 209, which AlN-substrate 103 is connected to the base 109 module (radiator plate), increases the reliability of the module. The base module made to improve the reliability of solder 106 in adverse conditions of Mo or Al-SiC has a smaller in comparison with the base made of a composite material Cu-Cu2O, the coefficient of thermal expansion. However, a base made of such materials, and has a small coefficient of thermal conductivity, and therefore the module with such a Foundation, has a high thermal resistance. The service life of the module whose basis is made of the proposed in the present invention is a composite material consisting of Cu-Cu2O at least five times the service life of the module whose base is made of copper, and its thermal resistance is 20% less than thermal resistance of the module whose base is made of Mo (with the same thickness of the base).

The above-mentioned features proposed in the present invention material expands possibilities when designing construe Cu-Cu2O base module shown in Fig.7, has a higher conductivity than the base, is made of Mo. In other words, the choice of such a material for the manufacture of the module base provides more efficient heat released during the work available in the module semiconductor elements. This reduces occur during operation, the temperature difference between the edges of the semiconductor element and the Central part. Due to this, the semiconductor element can be performed in 1,2 times the usual module. The increasing size of the semiconductor element can reduce the number of available module bipolar transistors with insulated gate from 30 to 24. Reducing the number of transistors in turn allows to reduce the dimensions of the module. Simultaneously, it is possible to use a substrate of aluminum oxide (as an insulating substrate), the conductivity of which is lower (approximately 20%) thermal conductivity of the substrate made of AlN. Aluminum oxide has compared to AlN higher Flexural strength, and therefore it is possible to make a larger substrate. Plate aluminum oxide has the training module. Due to this reduced the deformation (curvature) of the module. The increase in the size of the substrate due to its production of aluminum oxide can increase the number placed on it of semiconductor elements. In other words, the manufacture of a substrate of aluminum oxide can reduce the area required for isolation of each substrate, and the area required for isolation of the one substrate from another. Thus the conditions to reduce the size of the entire module.

In Fig.9A-9D shows a diagram illustrating the sequence of operations performed in the manufacture proposed in the present invention the module.

In Fig.9A schematically shown made of composite material Cu-Cu2O ready base module 109, the surface of which is coated with Nickel. The base has an essentially flat shape and is used as a finished item for the manufacture of the module.

In Fig. 9B schematically shows the base 109, United solder 205 with AlN-substrate 103. On the AlN substrate are connected by the solder 102 of the semiconductor elements 101. Upon cooling of the solder base 109, since its coefficient of thermal expansion different from coefficienta the reverse side of the module becomes concave.

In Fig. 9B schematically shows the housing 20$ module, assembled using a thermosetting adhesive. Upon cooling the adhesive to the reverse side of the module becomes almost flat, because the coefficient of thermal expansion of the housing is greater coefficient of thermal expansion of the Assembly 301, consisting of connected with each other by soldering of the module base and the substrate with semiconductor elements.

In Fig. 9D schematically shows the assembled module filled with silicone gel 212 and thermosetting epoxy resin 213. Because of the high coefficient of thermal expansion of the resin the reverse side of the module becomes convex.

In Fig. 10 shows a graph showing the magnitude of the deformation (warp) of the reverse side of the module base at different stages of the technological process of its manufacture. Positive strain values correspond to the concave shape of the reverse side of the base module, and a negative convex. Deformation module, the base of which is made of the proposed in the present invention a composite material Cu-Cu2O less (about three times) deformation of a conventional module in which the base is made of Mo. The reverse side of the finished module s in the coefficients of thermal expansion of the substrate and AlN-substrate, exceeds 100 μm (these results are not displayed in the chart). Module, the base of which is made of the proposed in the present invention a composite material Cu-Cu2O, slightly deformed, and therefore, it can be made larger than modules with bases made from conventional materials. At small deformation module on the stages of its Assembly deformation due to temperature changes during operation, is also insignificant. Small deformation module eliminates the possibility of leakage of grease, which is located between the surface of the base and adjacent the radiator.

In Fig. 11 shows an example of executing a powerful Converter, which uses proposed in the present invention the semiconductor module. Shown in this drawing, the transducer is a two-level inverter. Forming the inverter power semiconductor devices 501 is installed on a greased heat-dissipating grease 510 surface of the aluminum heat sink 511 and are fastened thereto the clamping bolts 512. Usually two existing inverter semiconductor module 501 are mounted on the heat sink symmetrical to each other relative who Torno bus 502, and an emitter bus 504 is supplied from a source 509 voltage across the United with them phase U, V and W. the Management of each IGBT module 501 is controlled by signals supplied to it over the wire 505, going to the gate, the auxiliary wire 506, going to the emitter, and the auxiliary wire 507, going to the collector. The load, which operates the inverter, indicated in the diagram position 508.

In Fig. 12A and 12B shows graphs describing the deformation module. The graphs shown in Fig. 13A and 13B, characterize the deformation of the rear side of the module (the thickness of the grease), measured before and after tightening the bolts on the module. Thus in Fig.12A and 12B shows the deformation module made in accordance with the present invention, and Fig.13A and 13B - deformation module manufactured by the conventional methods. A module with a base made of a conventional material (A1-SiC), the maximum deformation of its convex back side is about 100 μm. However, when applied to the surface of grease and then the bolts holding the module in its deformed shape of the reverse side is changed from convex to concave, because while tightening the bolts, the module is released from the surface of the heat sink layer applied thereto grease. The result of this t thermal resistance in place fit the base of the module to the bearing surface of the block. In contrast, the module, the base of which is made of the proposed in the present invention a composite material Cu-Cu2O, the initial deformation of the reverse side of the base is about 50 μm, and after applying grease and bolts thickness of the lubricant in the Central part of the module is equal to 50 μm. This is due to a sufficiently high rigidity of the base. Thus, the deformation is proposed in the invention of the module is two times less deformation of the conventional module with a base made of Al-SiC. In addition, in the proposed invention the module grease has almost the same thickness over the entire surface of its Foundation. Deformation of the base module associated with compression of grease during tightening of bolts of fastening of the module, typical for a module with a base made of copper, which has a lower hardness than the base, made of alloy si Cu2O. it is Obvious that the manufacture of the base module of the present invention alloy Cu-Cu2O solves this problem.

From the above graphs it follows that the base made of the proposed in the present invention alloy, si-si

Example 7
This example describes the use of the proposed and 15 plastic housing IP. In the variant shown in Fig.14, the plate radiator is closed and is located inside the housing. In the variant shown in Fig.15, plate heat sink is open and is located on the outer surface of the shell.

Plate heat sink made of composite material, si-si2About with different contents of si2Oh, which varies from 20 to 55 vol.%. In the temperature range from room temperature up to 300oWith the coefficient of thermal expansion of such a composite material is h-6/oTo h-6/oC. Approximately the same coefficient of thermal expansion is and the molding resin. Plate heatsink machined and Nickel plated.

The housing structure shown in Fig.14. Inside this housing is Nickel-plated radiator plate 33 made of the proposed in the present invention the copper composite material. To the radiator plate 33 insulation polyimide tape 32 is attached lead frame 31. Top plate to the heat sink 33 is soldered IP 34. Lead frame are connected is made of a gold conductor 35 Al-electrode of IP. All of these elements of the module, except for some parts of the leadframe, filled a. Case open plate heat sink shown in Fig. 15 differs from the case shown in Fig.14, so that the radiator plate 33 is open and is located outside of the filled molding resin inner part of the body.

The above enclosures with IP measured the deflection plate of the radiator and at the same time they were checked for cracks at the junction of the plate radiator with molding resin. It was found that when the difference of coefficients of thermal expansion of the plate radiator and the molding resin is not greater than 0,5x10-6/oWith, the deformation of the plate radiator are so insignificant, that in the place of its connection with the molding resin no cracks does not occur, and the molding resin remains intact. It was also found that a composite material when the content of si2About within 20-35 vol.% has high (200 W/(mK)) thermal conductivity coefficient.

Example 8
In this example the ceramic housing IP with plate heat sink made of the proposed in the present invention the copper composite material described above in examples 1-5. In Fig.16 and 17 pocketparty layer of Nickel plate heat sink 42. Plate heat sink 42 is soldered to made of Al2O3the housing 43. In case there is copper conductors and pin contacts 44 for connection to IP with the circuit Board. Located inside the copper conductors are connected to the aluminum electrode IP aluminum wire 45. All of these elements are covered with resin. To the housing containing silver solder soldered welding ring 46 made of Kovar alloy. Using a roller electrode to that of the welding ring is welded to the cover 47, also made of Kovar alloy. In Fig.17 shows a ceramic body (performed similarly to the case shown in Fig.16) with the installed heat sink 48 with cooling ribs.

Example 9
In this example we have considered the case with plate heat sink made of the proposed in the present invention the copper composite material described above in examples 1-5. Made this case by the method TAB (automated adherence of crystals to the beam conclusions on tape media). In Fig.18 and 19 shows the cross section of such a body.

In Fig.18 shows IP 51, which is thermally conductive resin 52 is connected with Nickel plated radiator plate 53. IP has the gold connected with performed according to the method TAB connection 55. This connection 55 is connected, in turn, a thin conductive film 56 with the lead frame 57. Tightness IP is provided a ceramic substrate 59, the ring 60, the sealing glass layer 61 and located between the IP and the ceramic substrate silicone rubber 58.

Tightly filled in the resin case shown in Fig.19. IP 65 soldered made of an alloy of Au-Si solder 66 is covered with a layer of Nickel plate radiator 67 made of the proposed in the present invention a composite material. Plate heat sink 67 thermally conductive resin 68 is connected to a grounded copper plate 69, which, in turn, the same resin is connected with Nickel plated and made of the proposed in the present invention a composite material plate heat sink 70. Located on the other side is output via gold-plated bump 71 is connected with performed according to the method TAB connection 72 and with them covered with resin 73. Lead frame 57 plate and the radiator is not completely filled with resin and have visible areas. Performed by the methods TAB connection is attached to the copper grounding plate, made on the basis of epoxy resin and containing silver paste 74. the linen is provided in the present invention the copper composite material, discussed above in examples 1-5. In Fig.20 shows a cross section of such a multichip module. Available in this module radiator plate 83 are compression molded from sintered blanks (or after rolling, or no rolling).

IP 81 is connected is made of a gold conductor 82 is carried out on the Nickel plated surface of the radiator plate 83 made of the proposed in the present invention a composite material, in the form of a thin film conductor 84. IP connected also made of gold conductor wired, made in made of AlN housing 85. Made in the building wiring connected to an external output 86. IP hermetically closed by a cap 87 which is connected to the frame 88 of made of Au-Sn alloy solder located between metallizirovannykh layers of the body.

Example 11
In this example the electrostatic attractor with a dielectric plate made of the proposed in the present invention a composite material. In Fig.21 shows a cross section of such attractor.

It is shown in Fig.21 electrostatic attractor is used as a stand or table in the installation of DL is of conductive material, any of the semiconductor material. When the supply voltage (about 500) from a source 91 of direct current to the electrode 94 of the electrostatic attraction between the dielectric plate 92 and the workpiece 90 occurs electrostatic force of attraction. Under the action of this force the workpiece 90 is attracted to the surface of the dielectric plate. In this case, the dielectric plate is made of a composite material described above in examples 1-5.

Item 90, on which the coating is applied coating, mounted on the dielectric plate electrostatic attractor. Then in the vacuum chamber 95 via United with its exhaust pipe 97 vacuum pump generates the necessary vacuum (of the order of 1x10-3PA). Installed on is connected to the inlet pipe 96 camera mainline valve opens and the vacuum chamber 95 with a volumetric rate of about 10 cm3gas (argon or other), in the atmosphere which is the process of spraying. At this point, the vacuum in the vacuum chamber falls to approximately 2x10-2PA.

Then on the electrode 94 electrostatic attractor voltage high frequency (13.56 MHz, supply, applied to the electrode of the electrostatic attractor is 2 kV (VRS4 kV (Vpp). To reconcile the full resistance of the voltage source and the vacuum chamber and the effective use of power source voltage for education in the vacuum chamber of the plasma is matching block 98 mounted between the electrode 94 electrostatic attractor and the source of 93 high-frequency voltage.

During deposition the temperature of the workpiece rises to 90 450oC. At this temperature made from the proposed invention is a composite material of the dielectric plate 92 electrostatic attractor remains intact and does not crack (which could lead to deposition on the workpiece foreign substances). Thus, the proposed invention the electrostatic attractor can increase the reliability of the coating process (and the quality of the obtained coating).

It should be noted that in the invention the electrostatic attractor can equally well be used in other units, designed to handle different conductors or semiconductors (e.g kremna the dielectric plate can be used as a table or stand in installations for the chemical deposition from the vapor (gas) phase, the equipment for condensation from the vapor phase, plants for grinding, facilities for etching, facilities for ion doping and other installations of a similar type.

Used in electrostatic attractor dielectric plate made of the proposed invention is a composite material, when required thermal resistance also has a sufficiently high dielectric strength. Use as prescribed in designed to handle various parts of the vacuum chamber electrostatic attractor is made of the proposed in the present invention a composite material of the dielectric plate as a table or stand eliminates the possibility of cracking of the dielectric plate and reduces the likelihood of falling into sprayed on the workpiece coating extraneous substances.

Proposed in the present invention, the composite material has a low thermal expansion, high thermal conductivity and well handled pressure. Therefore, it can be successfully used for mass production of various products with a relatively low number of technological operations.

Pre phase (which has very high thermal conductivity and phase oxide monovalent copper (cu2O) (having a low thermal expansion), and therefore he also has the properties of both of its components (i.e., high conductivity, and low thermal expansion). Proposed in the present invention a composite material with a corresponding content of copper (cu) and monovalent oxide of copper (cu2O) has a low coefficient of thermal expansion and high thermal conductivity. Proposed in the present invention, the composite material may find application in the manufacture of plate heat sinks for semiconductor devices and dielectric plates for electrostatic attractors.


Claims

1. Composite material consisting of metal and inorganic particles with less than metal, the coefficient of thermal expansion, wherein the inorganic particles dispersed in the metal so that at least 95% of the particles on the area occupied by them in cross-section, form an interconnected aggregates of complex shape.

2. Composite material consisting of metal and inorganic particles with less than metal, the coefficient of thermal rasshirenie section of the material, while the rest of the particles dispersed in the metal, form interconnected aggregates of complex shape.

3. Composite material consisting of metal and inorganic particles with less than metal, the coefficient of thermal expansion, wherein in the range of 20-150oWith its coefficient of thermal expansion increases on average (0,025-0,035)10-6/oWith the change in the coefficient of thermal conductivity at 20oWith 1 W/(mIt).

4. Composite material consisting of copper particles, copper oxide, characterized in that the particles of copper oxide dispersed in a copper so that at least 95% of the particles on the area occupied by them in cross-section, form an interconnected aggregates of complex shape.

 

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