Tungsten Copper Sheet Sintering Method
Tungsten copper alloy is not a copper bonding phase consisting of tungsten particles and a face-centered cubic structure of the body-centered cubic structure, both the solution nor to each other to form intermetallic compounds, are composites. Tungsten copper alloy commonly referred to as pseudo-alloy or false alloy, both high strength, high hardness, low coefficient of expansion and other characteristics have tungsten, copper also has high plasticity, and good electrical and thermal conductivity and other properties, therefore, LSI and high-power microwave devices, tungsten copper alloy material as the substrate, embedded blocks, connectors and cooling components developed rapidly. High thermal conductivity and heat resistance tungsten copper alloy greatly improved the use of power microelectronic devices, the device size; and a suitable coefficient of thermal expansion may be silicon microelectronic devices, gallium arsenide and other semiconductor materials and ceramic materials very useful good match link, to avoid thermal fatigue damage caused by thermal stress; these unique combination of properties makes tungsten copper alloy sheet in LSI and high-power electronic devices as electronic packaging and thermal deposition materials have been widely used.
Tungsten Copper Sheet Sintering MethodExisting tungsten copper sheet sintering method include the following:
1. Ultrafine / nano-alloy powder sintering method directly; this method uses mechanical alloying, sol-gel
France, a thermo-chemical process machinery synthesis of ultrafine tungsten copper was mixed powder, after forming, sintering at 1200 ℃ a 1350 ℃, can be directly made of various components of high density tungsten-copper alloy.
2. Activated liquid phase sintering method; the method adding a trace amount (0. lwt% a 0. 5wt%) a third metal element Pd, Ni, Co or Fe in tungsten-copper and other materials to promote copper insoluble in the tungsten phase was dissolved in the copper phase by forming a Y phase containing these metal elements in the liquid phase during sintering, thereby reducing the sintering temperature, sintering time is shortened, and greatly improve the sintered density.
3. An infiltration method; tungsten powder which is first compressed into briquettes, and then calcite at a temperature and for preparing a porous tungsten skeleton with a certain density and strength, after the low melting point metal to infiltrate the molten copper tungsten skeleton, thereby obtaining a dense tungsten copper alloy material. Mechanism of this method is that when the liquid metal wetting the porous substrate, the molten metal filling the pores of porous tungsten skeleton capillary force at the gap along the particle flow, so as to obtain a dense material.
However, a closer analysis shows that the sintered technology, sintered tungsten copper alloy existing methods are a series of problems:
1) For the ultrafine / nano-alloy powder sintering direct, long preparation time (generally) 50h), small-scale production capacity, which have limited the industrial production; and significantly grow the grain size after the solid-phase sintering, with other conventional After sintering method similar size, microstructure and other liquid-phase sintering is also similar; in addition, the method also easy to introduce other impurity elements affecting the final product performance.
2) Activation of activator liquid phase sintering method of adding significantly lower thermal conductivity properties, this method requires a high electrical and thermal conductivity of microelectronic materials is unfavorable.
3) An infiltration method in the infiltrated need be machined to remove excess copper metal, but this method increases the subsequent machining costs, reduce the yield, and not conducive to the use of the components of complex shape.
Mainly due to the presence of the above-described prior art analysis of each of the above methods is that many defects although tungsten and copper has good wettability, but due to significant differences between the two physical properties, and therefore is directly sintered in the conventional case, even if the liquid phase sintering, it is impossible to directly obtain high density sintered products. Therefore, how to make use of appropriate methods based on the activation of the elements without adding high-density sintered and two-phase distribution of tungsten copper alloy, and high production efficiency, avoiding the subsequent processing steps, is the key to overcome the deficiencies of the prior art One technical problem is the preparation of tungsten copper alloy technician solved.
Technical problems sintering tungsten copper sheet to be solved is to overcome the existing sintered tungsten copper alloy technology, the long preparation time ultrafine / nano-alloy powder sintering method of direct, small-scale production capacity, product has not greatly improved microstructure and Easy introduction of impurities affect product performance; or activation of activator liquid phase sintering method can significantly reduce the added thermal conductive properties of the material, not suitable for the requirements of high electrical and thermal conductivity of microelectronic materials; or after infiltration method requires machining costs, lower yields, is not conducive to the use of complex parts such as defects in shape, provided a tungsten-copper alloy sheet sintering method.
Tungsten Copper Sheet Sintering Method CaseTungsten copper sheet sintering method of the present invention, comprising the steps of: a hydrogen atmosphere, the tungsten-copper alloy raw slab 0. 4mm thickness 2. Omm a continuous liquid phase sintering can push the boat; which, continuous liquid phase sintering conditions push the boat in pushing the boat speed is 0. 15cm / min a 0. 5cm / min; a sintering temperature of 1250 ℃ 15500C; a holding time of 1 4 hours.
In the present invention, wherein the thickness of 0. 4mm a 2. Omm tungsten copper alloy raw slab may be prepared according to conventional methods in the art, generally molding or cold isostatic pressing method, also commercially available. For the present invention, 0.4 twenty-one 2. Omm thickness of choice, inventors have found that a large number of experimental studies, within the scope of this particular choice, the alloy used to prepare raw slab of tungsten copper alloy sheet, with the sintering method The other conditions are very conducive to the discharge of copper phase diffusion and sintering pores and directly simplify subsequent processing procedures sintering methods. Among them, the content of each component-oriented field of conventional tungsten copper alloy of tungsten and copper content of the metal tungsten copper alloy raw slab described, generally a tungsten content of 50wt% 90wt; copper content l0wt% ~ 50wt% .
The present invention, the hydrogen atmosphere in the sintering process of the invention, the hydrogen reduction of tungsten and copper can be oxidized, tungsten copper surface area of the two phases can be increased, to further facilitate the combination of tungsten-copper two-phase.
The present invention, the continuous liquid phase sintering in the art push the boat normal operation, typically the alloy ingot in a high temperature furnace continuously push the boat liquid phase sintering, specific to the present invention, the present invention is particularly preferably combined with specific conditions, continuous liquid phase sintering push the boat to make tungsten copper alloy of copper slab melting phase front to back since, first molten copper phase can fully penetrate tungsten skeleton, so more favorable exhaust vent, to further improve the density of the sintered product.
Wherein the continuous liquid phase sintering push the boat sintering temperature of 1250 ℃ a 15500C, when raw slab of tungsten copper alloy in this temperature range for high temperature liquid phase sintering, the preferred temperature is particularly advantageous to reduce the tungsten copper wetting angle of the two phases, so that the two-phase tungsten copper evenly distributed, and improve the sintering density.
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