EP0170867B1 - Procédé de fabrication d'un materiau composite - Google Patents

Procédé de fabrication d'un materiau composite Download PDF

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Publication number
EP0170867B1
EP0170867B1 EP85108013A EP85108013A EP0170867B1 EP 0170867 B1 EP0170867 B1 EP 0170867B1 EP 85108013 A EP85108013 A EP 85108013A EP 85108013 A EP85108013 A EP 85108013A EP 0170867 B1 EP0170867 B1 EP 0170867B1
Authority
EP
European Patent Office
Prior art keywords
copper
molybdenum
powder
sintered
powder mixture
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85108013A
Other languages
German (de)
English (en)
Other versions
EP0170867A1 (fr
Inventor
Georg Werner Dipl.-Phys. Reppel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vacuumschmelze GmbH and Co KG
Original Assignee
Vacuumschmelze GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vacuumschmelze GmbH and Co KG filed Critical Vacuumschmelze GmbH and Co KG
Publication of EP0170867A1 publication Critical patent/EP0170867A1/fr
Application granted granted Critical
Publication of EP0170867B1 publication Critical patent/EP0170867B1/fr
Expired legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0425—Copper-based alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001—Technical content checked by a classifier
    • H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

  • the invention relates to a method for producing a composite material from copper and at least one of the metals molybdenum and tungsten, in particular as a substrate material for power semiconductors, according to the preamble of patent claim 1.
  • thermally conductive bodies e.g. Copper
  • hard or soft solder interfaces are often used between the various elements to withstand repeated thermal cycling.
  • a break can easily occur during the changing temperature stress, in particular if a high current carrying capacity of the semiconductor arrangement is required.
  • Attempts have also been made to produce a composite material from a sintered combination of powders to form a compensating element US Pat. No. 3,097,329.
  • the surface facing the semiconductor element consists of molybdenum, while the opposite surface, which is in contact with the heat-dissipating body, consists mainly of copper.
  • this element has the low coefficient of expansion of molybdenum, so that this side can be brought together with a semiconductor body almost without thermal stresses, and on the other hand, it has the high coefficient of thermal expansion and the better electrical conductivity of copper.
  • the production of these individual elements with a graded molybdenum content is very complex and, due to the pressing process, only allows a limited shape of the pressed body.
  • the sintered body disadvantageously has a high residual porosity, which lowers the conductivity and means that the compact molded part cannot be subjected to any further deformation to increase the density and increase the strength.
  • US Pat. No. 3,685,134 discloses a method for producing a contact material from an electrically and thermally highly conductive material, such as copper, silver, gold or the like, and a material which is difficult to melt, such as tungsten, titanium, molybdenum, in which these materials in powder form with a particle size of 4 to 20 pm are thoroughly mixed, pressed and sintered in a protective gas atmosphere between 1140 and 1300 ° C. These sintered bodies are then cold-formed by a third of their cross section, then sintered for further compression and easier deformability and then repeatedly rolled and annealed, the cross section being reduced by 10 to 30% with each repetition.
  • the proportion of the material with good electrical conductivity is between 20 and 80% by weight.
  • the contact material produced in this way has a matrix made of the electrically and thermally highly conductive material, in which the difficult-to-melt particles are distributed approximately uniformly and are oriented in the rolling direction. As a micrograph of this contact material shows, the hard-melting particles hardly deform.
  • the coefficient of thermal expansion is never smaller than that of the fiber particles, a certain coefficient of thermal expansion of the composite material can be set on the one hand and the arrangement of the fiber particles on the other by appropriate selection of the fiber material.
  • the composite material can be adapted to the thermal expansion behavior of the semiconductor material.
  • the invention has for its object to develop a method of the type specified in the preamble of claim 1 such that it is easier to implement than the known methods and with which a pronounced fiber structure of the powdery particles can be achieved in the rolling direction.
  • the composite material produced by the method according to the invention differs from the contact material according to US Pat. No. 3,685,134 by a finer and significantly more pronounced fiber structure, as is shown by corresponding micrographs, which is essentially due to the fact that immediately after the sintering process, a hot forming process with a correspondingly high level Cross-sectional reduction takes place, in which not only the electrically and thermally conductive particles, but also the melting particles are deformed. In the known method, apparently only the electrically and thermally conductive particles are deformed, while the melting particles are essentially only distributed and directed.
  • the one according to the invention differs in a much finer distribution and structuring of the particles, which can be attributed to the particles that are many orders of magnitude smaller than the relatively coarse fibers in the conductive matrix.
  • the fibrous microstructure is produced by reshaping from an isotropic starting material, while according to US Pat. No. 3,969,754 the anisotropic material is already produced by embedding fibers in a metallic matrix during the initial shaping.
  • the deformation step to achieve the fiber structure can preferably be carried out by rolling or extruding the compacted body in the temperature range from 500 to 1000 ° C. It is particularly advantageous that the method according to the invention enables the production of any desired semi-finished forms, such as, for example, ribbon and wire.
  • the figure shows a longitudinal section of the structure of a copper-molybdenum powder composite material produced by the method according to the invention in a magnification of 250 times.
  • the alloy systems Cu-Mo, Cu-W and Cu (Mo, W) have little or no mutual solubility at room temperature.
  • Molybdenum has a thermal expansion coefficient a in the temperature range from 20 to 400 ° C of 5.5. 10-6 K- 1 , a thermal conductivity ⁇ at room temperature of 137 W / (K ⁇ m) and a specific electrical resistance p of 5.4 ⁇ Q cm at 20 ° C.
  • Copper has a thermal coefficient of linear expansion a of about 16 - 10- 6 K -1 , a thermal conductivity ⁇ of 380 W / (K - m) and a specific electrical resistance p of 1.7 ⁇ ⁇ cm. Depending on the proportion of the respective components in the powder composite, it is possible to set the desired properties.
  • very fine powders with an average particle size in the range from 1.5 to 6 ⁇ m are used and the sintering is carried out with a liquid copper phase in a reducing sintering atmosphere. With these process conditions, a single sintering step is sufficient to obtain a very high density with a low, closed residual porosity.
  • the subsequent further compaction to an almost pore-free body can take place either by hot isostatic pressing or - at the same time as deformation - by extrusion and / or rolling.
  • the sintered body could not be hot or cold worked because it still had an open porosity.
  • copper-molybdenum compacts were first made from fine powder mixtures (average particle size about 4 ⁇ m) with different copper proportions and then subjected to sintering above a temperature of 1150 ° C. under a hydrogen atmosphere.
  • the precise sintering conditions and the respective densities of the sintered and then deformed body can be found in Table 1.
  • the sintered bodies which had a diameter of 72 mm, were first placed in an 800 mm long tube made of a low-alloy steel alloy, e.g. Steel of grade St37, encapsulated.
  • the wall thickness of the cladding tube was 15 mm.
  • the pipe ends were vacuum-sealed with sealing pieces.
  • the interior was evacuated via a drainage tube fitted in one of the closure pieces and then closed.
  • the encapsulated sintered bolts were then hot-rolled into slabs at a temperature of 830 to 1000 ° C. and then cold-rolled to a strip with a thickness of 2 to 9 mm with a total degree of deformation of at least 50%.
  • An intermediate annealing at 800 ° C was partly inserted between the cold forming steps.
  • the joint deformation of the composite material in a cladding tube has proven to be an extraordinarily favorable method in terms of production technology.
  • the remaining covering material can then be milled or removed for further processing.
  • After an intermediate annealing, which may be necessary, the cross section of the strip can be further reduced without difficulty. Further finishing steps, such as grinding and electroplating, can follow in a known manner.
  • the sizes given in Table 2 for the electrical and thermal conductivity and for the coefficient of linear expansion a in the temperature range from 20 to 400 ° C were measured on finely ground blanks.
  • the composite materials produced by the process according to the invention not only have an extraordinary combination of properties, but also have special process engineering advantages over the production of pure molybdenum or tungsten.
  • molybdenum or tungsten require sintering temperatures of close to 2000 ° C. or above 2500 ° C., while temperatures of approximately 1150 to 1250 ° C. are preferably sufficient for the composite materials according to the invention.
  • Another significant advantage can also be seen in the fact that the temperatures for the deformation step according to the invention do not have to exceed 1000 ° C.
  • the composite materials produced by the method according to the invention are preferably used as substrate material for power semiconductors, where they are in close contact with the semiconductor and the heat-dissipating material.
  • these composite materials are also suitable for all other applications in which high electrical and thermal conductivity and a relatively low coefficient of expansion are important, e.g. for electrodes or contact elements of vacuum switches.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)

Claims (8)

1. Procédé d'obtention d'une matériau composite à base de Cuivre et d'au moins un des métaux Molybdène et Tungstène, en particulier comme matériau de substrat pour des semi-conducteurs de commande, pour lequel les produits qui se présentent sous forme pulvérulente sont pressés en corps moulés, et frittés, et les corps frittés sont soumis ensuite à une déformation mécanique, avec les étapes de procédé suivantes:
a) mélange de la poudre de Cuivre avec la poudre de Molybdène et/ou la poudre de Tungstène ayant une taille moyenne de particules en-dessous de 10 pm,
b) compression du mélange de poudres,
c) frittage du mélange de poudres à une température endessus du point de fusion du Cuivre,
d) déformation à chaud du corps fritté à une température en-dessous de 1000°C d'au moins 50% en une étape,
e) déformation à froid du corps fritté en vue d'une nouvelle réduction de la section jusqu'à une dimension finale.
2. Procédé selon la revendication 1, caractérisé en ce que le corps fritté est enfermé pour la déformation à chaud dans un tube-étui.
3. Procédé selon la revendication 1 ou 2, caractérisé en ce qu'on utilise un mélange de poudres à base de 30 à 80% en poids de Molybdène et/ou de Tungstène, le reste étant du Cuivre.
4. Procédé selon la revendication 1 ou 2, caractérisé en ce qu'on utilise un mélange de poudres à base de 40 à 65% en poids de Molybdène, le reste étant du Cuivre.
5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que le mélange de poudres contient environ 53% en poids de Molybdène, et comme reste du Cuivre.
6. Procédé selon l'une des revendications 1 à 5, caractérisé en ce que la taille moyenne des particules s'élève à environ 1,5 à 6 pm.
7. Procédé selon au moins l'une des revendications 1 à 6, caractérisé en ce que le composé pulvérulent est fritté à une température située entre 1150 et 1250 °C pour laquelle le frittage dure au moins une demi-heure.
8. Procédé selon au moins l'une des revendications 1 à 7, caractérisé en ce qu'on effectue une calcination intermédiaire entre les étapes de déformation à froid.
EP85108013A 1984-07-21 1985-06-28 Procédé de fabrication d'un materiau composite Expired EP0170867B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843426916 DE3426916A1 (de) 1984-07-21 1984-07-21 Verfahren zur herstellung eines verbundwerkstoffes
DE3426916 1984-07-21

Publications (2)

Publication Number Publication Date
EP0170867A1 EP0170867A1 (fr) 1986-02-12
EP0170867B1 true EP0170867B1 (fr) 1988-08-24

Family

ID=6241213

Family Applications (1)

Application Number Title Priority Date Filing Date
EP85108013A Expired EP0170867B1 (fr) 1984-07-21 1985-06-28 Procédé de fabrication d'un materiau composite

Country Status (2)

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EP (1) EP0170867B1 (fr)
DE (2) DE3426916A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3731624A1 (de) * 1987-09-19 1989-03-30 Asea Brown Boveri Ausgleichsronde fuer leistungshalbleitermodule
AU615964B2 (en) * 1987-09-28 1991-10-17 Fine Particle Technology Corp. Copper-tungsten metal mixture and process
US5062025A (en) * 1990-05-25 1991-10-29 Iowa State University Research Foundation Electrolytic capacitor and large surface area electrode element therefor
US5043025A (en) * 1990-06-12 1991-08-27 Iowa State University Research Foundation, Inc. High strength-high conductivity Cu--Fe composites produced by powder compaction/mechanical reduction
DE19934554A1 (de) * 1999-07-22 2001-01-25 Michael Stollenwerk Wärmetauscher
US7083759B2 (en) 2000-01-26 2006-08-01 A.L.M.T. Corp. Method of producing a heat dissipation substrate of molybdenum powder impregnated with copper with rolling in primary and secondary directions
EP1553627A1 (fr) * 2000-04-14 2005-07-13 A.L.M.T. Corp. Matériau de plaque de dissipation thermique sur laquelle est monté un semi-conducteur, et boitier céramique obtenu
CN104308151B (zh) * 2014-10-31 2016-04-20 西安瑞福莱钨钼有限公司 一种连续烧结制备钼铜合金坯料的方法

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE613878C (fr) * 1932-03-06 1935-05-25
GB732029A (en) * 1952-10-28 1955-06-15 Mallory Metallurg Prod Ltd Improvements in and relating to the production of high density metal bodies such as electrical contact bodies
GB810678A (en) * 1955-07-30 1959-03-18 Heck Friedrich A method of producing copper strip from the powdered metal
US2983996A (en) * 1958-07-30 1961-05-16 Mallory & Co Inc P R Copper-tungsten-molybdenum contact materials
GB883429A (en) * 1959-06-26 1961-11-29 Mallory Metallurg Prod Ltd Improvements in and relating to the manufacture of electrical contact or welding electrode materials
NL264799A (fr) * 1960-06-21
FR1338779A (fr) * 1961-11-08 1963-09-27 Texas Instruments Inc Perfectionnements aux contacts électriques
US3685134A (en) * 1970-05-15 1972-08-22 Mallory & Co Inc P R Method of making electrical contact materials
JPS5116302B2 (fr) * 1973-10-22 1976-05-22

Also Published As

Publication number Publication date
DE3426916A1 (de) 1986-01-23
EP0170867A1 (fr) 1986-02-12
DE3564590D1 (en) 1988-09-29

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