CN1150343C

CN1150343C - SiAl alloy with low expansibility and high thermal conductivity

Info

Publication number: CN1150343C
Application number: CNB011141247A
Authority: CN
Inventors: 冼爱平; 闵家源
Original assignee: Institute of Metal Research of CAS
Current assignee: Institute of Metal Research of CAS
Priority date: 2001-06-22
Filing date: 2001-06-22
Publication date: 2004-05-19
Anticipated expiration: 2021-06-22
Also published as: CN1393572A

Abstract

The present invention relates to a silicon-aluminium alloy with low expansion and high heat conduction, whose basic chemical formulation is 50 to 80 wt% of silicon and aluminum and unavoidable impurities as the rest. 0.01 to 1.0 wt% of a third component selected from one or more of boron, chromium, ferrum, titanium, vanadium, nickel, manganese and phosphorus can be added. The silicon-aluminium alloy can be prepared by a conventional hot-processing technology, and the thermal expansion coefficient of the alloy is continuously adjustable. The variation range of the alloy is from 6 to 12*10<-6>/K, the variation range of heat conductivity is from 110 to 150 W/mK, and specific gravity is from 1.7 to 2.5 g/cm<3>. The present invention is especially suitable for the electronic packaging of large-scale integration circuits, and heat-sink materials at occasions requiring high-strength heat dissipation, such as large-power thyristor bases, etc.

Description

A kind of silumin of low-expansion high heat conductivity

The invention belongs to the alloy material preparation field, specifically just provide a kind of novel silumin, it has low bulk, high heat conduction, low-gravity, easily processing and performance cheaply are with an urgent demand to the high-performance heat sink material such as the Electronic Packaging that adapts to large-scale integrated circuit.

In recent years, in microelectronics industry, fast development along with the large-scale integrated circuit technology, the integrated level and the packaging density of IC chip significantly improve, and cause that thus the heating problem of semi-conductor chip is outstanding day by day, especially Xin Yidai semiconductor material GaAs, after temperature raises, serviceability decreases sharply, (10 ℃ of the every risings of temperature, the element mean lifetime reduces about 1/3).

The packaged material of integrated circuit (IC) chip employing at present is electric plastics and Al ₂O ₃Stupalith etc., but the thermal conductivity of these materials is too poor, adapt to requirement far from, adopting the high heat conductance novel material is a key of current Electronic Packaging technology, in order to reduce the solder joint thermal stresses that causes by temperature variation, avoid issuable creep, tired and fracture, require the thermal expansivity (CTE) of packaged material to be complementary with semiconductor chip material as far as possible, (Si:CTE 4.1 * 10 ^-6/ K, GaAs:CTE 5.8 * 10 ^-6/ K), the ideal electronic package material also requires secular chemical stability in addition, and is nontoxic, and proportion is little, and certain mechanical strength and workability (as mechanical cutting, plating, be connected etc.) and with low cost are easy to multiple complex art economic targets such as manufacturing.

The main flow heat sink material of IC chip electronic package substrate is an alumina-ceramic at present, it is easy to get because of having raw material, nontoxic, thermal expansivity is little, stable chemical performance, price are lower etc., and advantage is widely used, but, can't adapt to the demand of IC chip of new generation owing to thermal conductivity too low (TC 20W/mK).In the heat sink material of developing, can be used as heat sink material after the metallic aluminium surface anodic oxidation, its thermal conductivity can reach 230W/mK (D.Mu et al J.Mater.Sci.Mater.Electronics, 11,2000,239), its main drawback is: thermal expansivity is too high, and (CTE 23.6 * 10 ^-6/ K) thus stress of sealing big, semiconductor element is easy to damage, low expansion alloy such as Kovar thermal expansivity less (5.8 * 10 ^-6/ K), but thermal conductivity also very low (TC17W/mK) is also littler than existing alumina-ceramic.Beryllium oxide ceramics has high heat conduction simultaneously, and (TC 260W/mK, CTE 7.2 * 10 for the advantage of low bulk ^-6/ K), but toxicity is very big, and a large amount of uses can cause serious environmental to pollute.Aluminium nitride (Hu Xiangyang etc., semiconductor technology, 25 (5), 2000,29) has good comprehensive performance (250W/mK, CTE4.5 * 10 ^-6/ K), but must solve the electroplating surface poor performance, shortcomings such as the bad and cost height of machinability.Refractory metal W, Mo and matrix material W-Cu thereof, Mo-Cu (Y.J.Zhang et al, Mater, Sci, Tech 15 (11), and 1999,337) also have the over-all properties of low-expansion high heat conductivity, (W:CTE 4.45 * 10 ^-6/ K, TC 168W/mK; Mo:CTE 5 * 10 ^-6/ K, TC 140W/mK; W/10:Cu CTE6.5 * 10 ^-6/ K, TC 209W/mK; Mo/10Cu:CTE7 * 10 ^-6/ K, TC180W/mK), the main drawback that these main flow pure metal or metal-base composites exist is a shortage of resources, material proportion is too big, and cost is very high.SiC/Al matrix material (J.C.Kim, dt al, J.Adv.Mater.31 (4), 1999,37) be a kind of low-expansion high heat conductivity material of developing, this material main drawback is that workability is bad, and cost is very high, can not carry out mechanical cutting processing with universal cutter, still not have a kind of desirable material in a word at present and can satisfy the integrated performance index that the hyundai electronics encapsulation technology proposes heat sink material.

The object of the present invention is to provide a kind of low-expansion high heat conductivity material---silumin, it has low thermal coefficient of expansion, high thermal conductivity, there is not toxicity, lower material cost, and be easy to processing, can be widely used for the encapsulation of large-scale integrated circuit or the occasion of this material of other demand.

The invention provides a kind of silumin of low-expansion high heat conductivity, it is characterized in that alloy formula composition scope is as follows, weight percent:

Silicon 50-80%

Aluminium and unavoidable impurities surplus.

In the silumin of low-expansion high heat conductivity of the present invention, can also add the 3rd constituent element 0.01-1%, the 3rd constituent element is selected from one or more in boron, chromium, titanium, vanadium, iron, manganese, nickel, phosphorus, the carbon.

Silumin provided by the invention can select a kind of manufacturing process of routine to carry out the preparation of alloy, and these technologies comprise the melting and casting method, powder metallurgic method and spray-up method etc.

In the present invention, silicon is alloy basal component, and it has thermal expansivity, and low (CTE 4.1 * 10 ^-6/ K), the characteristics of thermal conductivity height (TC:150W/mK) have a series of advantages such as stable, moderate hardness of light specific gravity, chemical property and with low cost, aboundresources simultaneously.The main drawback of silicon is fusing point very high (1410 ℃), and material fragility is big, thereby the preparation difficulty, and its machinability is also relatively low simultaneously, these shortcomings, and available Al supplies.

The main effect of aluminium has three among the present invention, and first as a kind of high heat conduction, high expansible material, and it can be used as second and adjusts the thermal expansivity of alloy mutually by the difference of additional proportion, and does not reduce the thermal conductivity of alloy.According to the basic theories Turner equation of heterogeneous composite material thermal expansion, α=(∑ α _iW _iK _i/ ρ _i)/(∑ W _iK _i/ ρ _i), α in the formula, α _iBe respectively the thermal expansivity of alloy or i phase, W _i, K _i, ρ _iBe respectively the weight percent of i phase, volumetric modulus of elasticity and density, the relevant data of substitution silicon, aluminium, the content that can calculate proper Al is when the 50-20% scope, and the thermal expansivity of alloy should be 6～11 * 10 ^-6Between/the K, therefore can be according to different thermal expansivity requirements, the counter content of asking Aluminum in Alloy.Second kind of effect of Al is the processability of improving alloy, makes it to carry out processing and manufacturing easily at low temperatures, thereby can significantly reduce manufacturing cost.Al-Si is a binary eutectic alloy, eutectic temperature only is 550 ℃, the fusing point of aluminium itself is also very low, only 660 ℃ of fine aluminium fusing points, be significantly less than the fusing point of pure Si, after in Si, adding an amount of Al, can reduce the fusing point of alloy itself greatly, this effect is no matter for the melt-casting of alloy, or the powder metallurgical technique route all has important meaning, it can allow to select low Heating temperature to carry out melting or powder sintered, so not only can save the relevant device investment greatly, also can increase substantially associated materials such as crucible, the work-ing life of mould etc., also can reduce thermal stresses in the product simultaneously, improve the product inner quality.The third advantageous effect of Al is the crystal grain caking agent as plasticity, disperse is distributed between the tiny silicon crystal grain in the microstructure of alloy, play and connect and the buffered effect, under the stress, plasticity is aluminium preferably outside, and the slippage of microcosmic can at first take place, deformation, position and growth trend are given birth to by the alliance that changes crackle, finally improve the fracture toughness property of material, and improve the machinability energy of alloy.

The 3rd constituent element is meant boron, chromium, iron, titanium, vanadium, nickel, manganese, phosphorus and carbon among the present invention, these constituent elements can be independent a kind of interpolations, or multiple compound interpolation, its effect is further to improve the melting of alloy or sintering process, suppress grain growth, obtain evenly tiny grain structure, and reduce alloy fragility, improve the comprehensive mechanical property of alloy, finally reach the purpose of making high performance material with low-cost technologies.

Advantage on the technology of the present invention is conspicuous:

1, the material coefficient of thermal expansion coefficient is 6 * 10 ^-6/ K and 11 * 10 ^-6Adjustable continuously in the/K scope, like this can be according to the difference of encapsulation matching materials, accurately the alloy formula of design mates both thermal expansivity fully, reaches the target of zero stress encapsulation.

2, under the condition that guarantees the low bulk coupling, have the effect of high thermal conductivity, thermal conductivity is greater than 100W/mK, to satisfy the needs of IC chip high strength heat radiation.

3, the low (2.0-2.5g/cm of alloy proportion ³), intensity height, specific rigidity be big, satisfying the following in advance of heat sinking function, can reach little, the lightweight effect of volume, the latter not only is adapted to the developing direction of modern electronic product, and is applicable to pressing for of modern aerospace industry such as aviation electronics and space vehicle.

4, alloy preparation technology is simple, and available common process is produced, and these technologies comprise powder metallurgic method, melt-casting method, spray up moulding etc., also have in addition abundant raw material, cheap, be suitable for a series of remarkable advantages such as production in enormous quantities.

Specific embodiments of the invention are described in detail in detail below:

Accompanying drawing 1 is embodiment 2 alloy x optical diffraction collection of illustrative plates;

Embodiment 1

Preparation 70%Si (weight percent, down together), all the other are the alloying constituent of Al; raw material is powder; original particle size is 100 orders (size of particles≤150 μ m), with the first ball milling 2 hours in ball mill of mixed powder, fills the Ar protection in the ball mill chamber; in case raw material oxidation; raw material through the ball milling thorough mixing evenly after, will mix the powder stock first cold prepressing moulding in the punching block of packing into, the base of will colding pressing then places and carries out hot pressed sintering in the graphite jig; 700 ℃ of sintering temperatures, pressure 5kg/mm ², soaking time is 30 minutes, stove is chilled to room temperature then.Obtain the densification of silumin quality behind the hot pressed sintering, crystal grain is tiny in the microstructure, and is evenly distributed, and the thermal conductivity of alloy is 120W/mK, thermal expansivity 6.5 * 10 ^-6/ K, and machining property is good, and available speedy steel cutting-tool carries out turning and boring, and also the method for available routine is carried out surperficial mechanical polishing and electroplate.

Embodiment 2

Preparation 50%Si, 0.3%Fe, 0.02%Cr, all the other are the alloy of Al, and raw material is powder, and ball milling and cold pressing forming process are identical with embodiment 1, the base of colding pressing carries out pressureless sintering under vacuum condition, 650 ℃ of sintering temperatures, soaking time are 1 hour, obtained fine and close alloy after stove is cold, silicon crystal grain is tiny in the alloy, and aluminium then is evenly distributed between the silicon crystal grain, x optical diffraction collection of illustrative plates (Fig. 1) discloses, in silumin, exist with single-phase separately between the sial, do not react mutually and dissolving.The thermal conductivity of sample is 140W/mK, thermal expansivity 6.5 * 10 ^-6/ K, available common speedy steel cutting-tool carry out mechanical cutting processing.

Comparative example

Preparation 85%Si, all the other are the alloy of Al, adopt to be prepared as embodiment 1 identical ball milling, die mould and hot-pressing sintering technique, fail to succeed, and sintered sample is inner loose, and intensity is lower, and this is because the amount cause very little of bonding phase Al.

Claims

1, a kind of silumin of low-expansion high heat conductivity is characterized in that alloy formula composition scope is as follows, weight percent:

Silicon 50～80%

Aluminium and unavoidable impurities surplus.

2, according to the silumin of the described low-expansion high heat conductivity of claim 1, it is characterized in that: add the 3rd constituent element 0.01-1% weight, the 3rd constituent element is selected from one or more in boron, chromium, titanium, vanadium, iron, manganese, nickel, phosphorus, the carbon.