A kind of graphite and alusil alloy composite electron encapsulating material and preparation method thereof
Technical field
The invention belongs to technical field of composite materials, and in particular to a kind of graphite and alusil alloy composite electron encapsulating material
And preparation method thereof.
Background technology
The height of the electronic building brick in the development and machine system in the fields such as electronic information field, aerospace field and traffic
Effect, high life, stable operation are inseparable, step into 21st century, and lightweight, integrated is more focused in the development of electronic building brick
And modular development, under this development trend, machine system military service stability is more depending on electronic building brick condition under arms
Under stable operation ability.Being related to temperature, chip or module to be matched with the thermal deformation of substrate and strong electronic building brick service condition more
Degree problem.The development trend and Service Environment of electronic building brick propose the requirement of harshness to encapsulating material:Possesses low-density, good
The combination properties such as thermal conductivity, suitable thermal coefficient of expansion and certain intensity.
Along with the development of electronics and information industry, the encapsulating material of all polymorphic types, such as Al, AlN, BeO, Invar are occurred in that
The materials such as alloy, Kavar alloys, W-Cu, Mo-Cu, diamond/Cu, Al-Si alloy, these materials are in density, thermal conductivity, warm
The coefficient of expansion, intensity, processing characteristics and manufacturing cost etc. are in a certain respect or certain several aspect has some superiority, and electronic information is produced
The Service Environment of industry development trend and electronic component causes that the electronic package material with good combination property is increasingly subject to
Pay attention to.
The features such as graphite has low-density, particular crystal plane high heat conductance, low thermal coefficient of expansion, good lubricity, makes it
There is greater advantage in terms of combined light, high heat conduction, low-expansion coefficient and excellent machinability encapsulating material is prepared.Graphite
It is poor with most metal interface wettabilities, therefore, it is compounded to form Electronic Packaging with other metals or alloy graphite is prepared
During material, graphite surface is pre-processed, graphite and compound phase boundary moisture ability can be improved, improve interface binding power,
Interface resistance is reduced, plating Ni treatment is carried out in the present invention to graphite surface.Possess certain intensity for guarantee prepares encapsulating material,
It is combined with graphite using alloy, and is strengthened by subsequent heat treatment, is played invigoration effect.Using the preferable Al- of mobility
Si alloys are prepared as compound phase beneficial to boundary moisture and shaping.Graphite has high thermal conductivity in particular crystal plane, and billet is prepared and adopted
With vacuum hot-pressing process, it is ensured that graphite flake layer direction is vertical with pressure direction.
The content of the invention
The present invention is directed to electronic package material the deficiencies in the prior art, there is provided a kind of graphite and alusil alloy composite electron
Encapsulating material and preparation method thereof, it is characterised in that the encapsulating material is made up of crystalline flake graphite and alusil alloy, wherein, scale
The percentage by weight of graphite is 35~70wt%, and the percentage by weight of alusil alloy is 30~65wt%;Crystalline flake graphite lamella side
To with pressing direction vertical distribution, in discontinuous arranged in parallel, alusil alloy is distributed in graphite flake layer gap, graphite flake to graphite flake
It is in laminated construction with alusil alloy;The density of the encapsulating material is 2.42~2.55g/cm3, parallel to graphite flake layer X-Y directions
Thermal conductivity is 240~280W/ (m.K), and 27 DEG C~100 DEG C of thermal coefficient of expansion is 10.2~13.9 × 10-6/ K, bending strength is
120~160MPa.
The alusil alloy, by weight percentage:9~14wt% of silicone content, 1~5wt% of copper content, content of magnesium is 0.5
~2.5wt.%, Theil indices are 0.1~1.5wt.%, balance of aluminium;The purity of the crystalline flake graphite is more than or equal to
99.9wt.%, granularity is 32 mesh~100 mesh.
The preparation method of a kind of graphite and alusil alloy composite electron encapsulating material, it is characterised in that comprise the following steps:
(1) aerosolization prepares alusil alloy powder:Alusil alloy under high-purity argon gas atmosphere, using aerosolizing device
Prepare atomized powder;
(2) flake graphite's surface pretreatment:By once soaking zinc, secondary soaking zinc and chemical nickel plating, in flake graphite's surface
One layer of nickel dam of plating, is cleaned and washes of absolute alcohol using deionized water, using liquid nitrogen by low-temperature distillation after suction filtration, removes part
Moisture, reuses vacuum drying box and removes moisture removal in 95~120 DEG C of 2~6h of drying;
(3) powder mixing:Crystalline flake graphite is premixed with alusil alloy atomized powder according to percentage by weight dispensing after pretreatment
After conjunction, it is put into be well mixed in mixing tank and is made mixed-powder;
(4) mixed-powder vacuum hotpressing:The powder that will be mixed loads in steel jacket, using bidirectional press by pre-
Be densified for composite powder by pressure, vacuum degassing, vacuum hotpressing process, is prepared into encapsulating material;
(5) machine:Encapsulating material after vacuum hotpressing is machined out to form parts.
The atomization temperature of the alusil alloy described in step (1) is 580~660 DEG C.
Alusil alloy atomized powder granularity prepared by step (1) is 200 mesh~800 mesh, and purity is more than or equal to
99.8wt.%, iron content is less than or equal to 0.008wt.%, Primary silicon particles≤90um in atomized powder.
Once the solution and technique of leaching zinc are described in step (2):450~580g/L of NaOH, 75~120g/ of zinc oxide
L, 8~20g/L of sodium potassium tartrate tetrahydrate, 0.5~4g/L of ferric trichloride, 0.2~2g/L of sodium nitrate, 35~80 DEG C of leaching zinc temperature, soak zinc
15~60s of time;The solution and technique of the secondary soaking zinc is:50~130g/L of NaOH, 15~65g/L of zinc oxide, wine
Stone acid potassium 10~35g/L of sodium, 1~4.5g/L of ferric trichloride, 0.5~2.5g/L of sodium nitrate, 35~80 DEG C of leaching zinc temperature, during leaching zinc
Between 15~60s;The solution and technique of the chemical nickel plating is:15~65g/L of single nickel salts, a hydration sodium hypophosphite 14~
56g/L, 14~60g/L of sodium citrate, 2~12g/L of sodium acid carbonate, 15~65mL/L of triethanolamine, ammoniacal liquor regulation pH value 8~
10,35~70 DEG C of nickel plating temperature, plating time is 10~35min.
The thickness of step (2) the flake graphite's surface nickel dam is 0.5~12um.
Step (3) 20~80r/min of the mixing tank rotating speed, ball material mass ratio 2~6, mixing time 16-32h.
Step (4) 20~40MPa of preload pressure, 0.5~2h of dwell time;The vacuum degassing is true to be taken out under normal temperature
It is empty to 2~5 × 10-2Pa;The vacuum hotpressing for heat up simultaneously vacuumize, heating rate≤50 DEG C/h, 80~130 DEG C, 150
1~4h is incubated between~200 DEG C, 400~450 DEG C, 500~600 DEG C respectively, after insulation terminates, vacuum≤1 × 10-2Pa,
580~660 DEG C of 4~6h of insulation, vacuum≤8 × 10-3During Pa, start compacting, 80~140MPa of pressing pressure, single depression amount
It is 3~5mm, each 10~40min of dwell time, when reaching maximum reduction, 2~5h of dwell time.
Step (5) is described be machined as in car, milling, mill and spark cutting one or more.
Electronic package material prepared by the present invention has following characteristic:
(1) lightweight:Electronic package material of the invention contains high-quality fraction, low-gravity crystalline flake graphite and low-density
Alusil alloy, its density be 2.42~2.55g/cm3, aluminium silicon, aluminium silicon carbide and Buddha's warrior attendant less than fine aluminium and homogenous quantities fraction
The electronic package material density such as stone aluminium;
(2) high heat conduction:Electronic package material of the invention uses the preferable crystalline flake graphite of heat conduction, parallel to graphite flake layer X-
Y-direction thermal conductivity improves a lot between 240-280W/ (m.K) compared with fine aluminium, higher than the thermal conductivity of similar alusil alloy.It is logical
Cross carries out chemical nickel plating to flake graphite's surface, improves graphite and alusil alloy boundary moisture ability, reduces interface resistance;
Meanwhile, Ni-coated graphite, when being mixed with relatively low ratio of grinding media to material process machinery, can further weaken due to one layer of nickel dam of surface attachment
Destruction of the stainless steel steel ball to graphite-structure, preserves the integrality of graphite-structure.
(3) controllable low thermal coefficient of expansion:The compound electronic package material of graphite of the invention and alusil alloy it is hot swollen
Swollen coefficient is 10.2~13.9 × 10-6/ K (27 DEG C~100 DEG C).The present invention uses chemical nickel plating combining powder metallurgical technology, adopts
Moisture removal is removed with low-temperature distillation and vacuum drying technique, loss of the graphite in plating process is greatly reduced, can be with standard
Really control the percentage composition of graphite.Meanwhile, in mechanical mixture technique, the amount of graphite and alusil alloy atomized powder is according to weight
Percentage can be with precise control, and then thermal coefficient of expansion is controllable;
(4) good interface binding power:Carry out chemical nickel plating by flake graphite's surface, significantly improve graphite with
The boundary moisture of alusil alloy, while the interfacial reaction of alusil alloy and nickel also improves interfacial force to a certain extent, drops
Low interface resistance.
(5) possesses certain intensity:Electronic package material material of the invention by after fixation rates, bending strength
120~160MPa is reached, average value reaches 140MPa;
(6) material densification, even tissue:The present invention combines nickel chemical plating technology, gas-atomized powder technique and powder metallurgy
Process advantage, using thinner alusil alloy atomized powder, by mechanical mixture, is sufficient filling with crystalline flake graphite gap, microcosmic group
Knit uniformly, without particle agglomeration.By vacuum hotpressing, while removing gas in encapsulating material, using graphite surface chemical nickel plating
And the polynary system liquid phase effect that alusil alloy is formed, the interface of good combination is formed in material, and flow by liquid phase
Filling crystalline flake graphite gap, makes material reach densification.Raw material graphite and alusil alloy atomized powder granularity that the present invention is used
Can choose within the specific limits, the microstructure size of prepared electronic package material can also be adjusted within the specific limits
It is whole.
(7) composition of material can be with precise control:The present invention is atomized using powder metallurgical technique to graphite and alusil alloy
Powder carries out mechanical mixture, and using weight than Composition Control, the selection of raw material is easy to precise control.Simultaneously using low-temperature distillation and
The moisture remained in middle graphite after the technique removal chemical nickel plating that vacuum drying is combined, can strictly control the amount of graphite.Remove
Outside this, in alusil alloy atomized powder preparation process, the addition of each element is added or used using clad type and first cast
Into the mode of intermediate alloy, then melted and atomization procedure, reduced scaling loss of each element in preparation process in alloy.
(8) good machinability:The alusil alloy of low body point is also relatively easy in electronic package material of the invention
Processing, while graphite has lubrication so that the machinability of encapsulating material is substantially improved, its machinability is better than same
The encapsulating materials such as class fine aluminium (knife easy to stick), aluminium silicon and aluminium silicon carbide.
Advantages of the present invention:
The present invention combines chemical nickel plating and powder metallurgical technique has been prepared and encapsulated with graphite and alusil alloy composite electron
Material, material reaches densification, and microstructure is uniform.The material have low-density, high heat conductance, low-expansion coefficient, with certain
Intensity and the features such as easily machine.Graphite prepared by the present invention compares other types with alusil alloy composite electron encapsulating material
Encapsulating material, combination property advantage is larger, has larger application potential in Electronic Packaging field.
Preparation method of the present invention:Leaching zinc is carried out to crystalline flake graphite and be prepared by nickel plating pretreatment, gas atomization
Go out alusil alloy powder, graphite and alusil alloy atomized powder mixed using mechanical mixture technique, using vacuum hotpressing
Densification operation.The preparation section can accurately control the composition of material, it is ensured that the uniformity of the microstructure of material and cause
Densification.Each operation of the invention is easily achieved, workable, can independently carry out.Electronic package material of the present invention
Preparation method, has greater advantages compared with prior powder metallurgy method.The preparation method material preparation cost, continuous prodution and
The aspects such as mass production also have some superiority.
Brief description of the drawings
Fig. 1 is the metallographic structure schematic diagram of graphite and alusil alloy composite electron encapsulating material.
Specific embodiment
A kind of graphite of the present invention and alusil alloy composite electron encapsulating material and preparation method thereof, it is below in conjunction with the accompanying drawings and real
Apply example and further illustrate the present invention, be not meant to limiting the scope of the invention.
Embodiment 1
The percentage composition for using crystalline flake graphite is 35wt%, and granularity is 100 mesh, and purity is 99.9wt%;Crystalline flake graphite is pre-
Treatment, a zinc dipping solution and technique are:NaOH 450g/L, zinc oxide 75g/L, sodium potassium tartrate tetrahydrate 8g/L, ferric trichloride
0.5g/L, sodium nitrate 0.2g/L, 35 DEG C of leaching zinc temperature, galvanizing time 60s;Secondary soaking zinc solution and technique are:NaOH
50g/L, zinc oxide 15g/L, sodium potassium tartrate tetrahydrate 10g/L, ferric trichloride 1g/L, sodium nitrate 0.5g/L, 35 DEG C of leaching zinc temperature, soak zinc
Time 60s;Nickel plating solution and technique are:Single nickel salts 15g/L, hydration sodium hypophosphite 14g/L, a sodium citrate 14g/L,
Sodium acid carbonate 2g/L, triethanolamine 15mL/L, ammoniacal liquor regulation pH value 8,35 DEG C of nickel plating temperature, plating time is 35min.By upper
After stating nickel plating, the average 0.5um of flake graphite's surface chemical Ni-plating layer thickness;Crystalline flake graphite after chemical nickel plating, using go from
Sub- water cleaning is repeatedly and washes of absolute alcohol repeatedly, after suction filtration uses liquid nitrogen by low-temperature distillation, removes part moisture, reuses
Vacuum drying box dries 6h between 95 DEG C.
The percentage composition of alusil alloy is 65wt%, wherein, the silicon from aluminum-silicon alloy content 9wt%, copper content
1wt%, content of magnesium 0.5wt.%, Theil indices 0.1wt.%, balance of aluminium.Alusil alloy atomization temperature is 580 DEG C, atomizing medium
It is high-purity argon gas, alusil alloy atomized powder iron-holder is 0.0075wt.%, primary silicon full-size 49um, is closed from 800 mesh
Bronze end.
Using ratio of grinding media to material 2, mixing tank rotating speed about 20r/min, incorporation time is carried out two kinds of powder for the technique of 32 hours
Mechanical mixture, mixed powder repeatedly sieves after removing steel ball and loads steel jacket.Before vacuumizing, pre-stamped, pressure is carried out
Power 20MPa, dwell time 2h.After powder packing is finished, 5x10 is evacuated under normal temperature-2Heated up after Pa, while taking out true
It is empty.Heat up and pressing process:35 DEG C/h of heating rate, is incubated 4h, each temperature respectively at 80 DEG C, 150 DEG C, 400 DEG C and 500 DEG C
After Duan Baowen terminates, vacuum is respectively less than equal to 1x10-2Pa.4h, vacuum 5x10 are incubated at 580 DEG C-3During Pa, start compacting, compacting
Pressure 80MPa, single depression amount is controlled in 3mm, each dwell time 10min, when reaching maximum reduction, dwell time 2h.
After the car of billet containing steel mold after vacuum hotpressing goes steel mold, required parts are processed into by machining processes.
Encapsulating material performance is as follows prepared by the present embodiment:Density 2.55g/cm3, parallel to graphite X-Y directions thermal conductivity
It is 240W/ (m.K) that thermal coefficient of expansion is 13.9 × 10-6/ K (27 DEG C~100 DEG C), bending strength reaches after solid solution aging
160MPa。
Embodiment 2
The percentage composition for using crystalline flake graphite is 70wt%, and granularity is 32 mesh, and purity is 99.9wt.%;Crystalline flake graphite is pre-
Treatment, a zinc dipping solution and technique are:NaOH 580g/L, zinc oxide 120g/L, sodium potassium tartrate tetrahydrate 20g/L, tri-chlorination
Iron 4g/L, sodium nitrate 2g/L, 80 DEG C of leaching zinc temperature, galvanizing time 15s;Secondary soaking zinc solution and technique are:NaOH 130g/
L, zinc oxide 65g/L, sodium potassium tartrate tetrahydrate 35g/L, ferric trichloride 4.5g/L, sodium nitrate 2.5g/L, 80 DEG C of leaching zinc temperature, during leaching zinc
Between 15s;Nickel plating solution and technique are:Single nickel salts 65g/L, hydration a sodium hypophosphite 56g/L, sodium citrate 60g/L, carbon
Sour hydrogen sodium 12g/L, triethanolamine 65mL/L, ammoniacal liquor regulation water-bath pH value 10,70 DEG C of bath temperature, plating time is 10min.Through
Cross after above-mentioned nickel plating, the flat thickness in this year of flake graphite's surface chemical Ni-plating layer is 12um;Crystalline flake graphite after chemical nickel plating, makes
Cleaned with deionized water repeatedly and washes of absolute alcohol repeatedly, after suction filtration use liquid nitrogen by low-temperature distillation, remove part moisture,
Reuse vacuum drying box and dry 2h between 120 DEG C.
The percentage composition of alusil alloy is 30wt.%, wherein, the silicon from aluminum-silicon alloy content 14wt%, copper content
5wt%, content of magnesium 2.5wt%, Theil indices 1.5wt%, balance of aluminium.Alusil alloy atomization temperature is 660 DEG C, and atomizing medium is
High-purity argon gas, alusil alloy atomized powder iron-holder is 0.007wt%, primary silicon full-size 61um, from 200 mesh alloyed powders
End.
Using ratio of grinding media to material 6, mixing tank rotating speed about 80r/min, incorporation time is carried out two kinds of powder for the technique of 16 hours
Mechanical mixture, mixed powder repeatedly sieves after removing steel ball and loads steel jacket.Before vacuumizing, pre-stamped, pressure is carried out
Power 40MPa, dwell time 0.5h.After powder packing is finished, 2x10 is evacuated under normal temperature-2Heated up after Pa, while taking out
Vacuum.Heat up and pressing process:50 DEG C/h of heating rate, 1h is incubated between 130 DEG C, 200 DEG C, 450 DEG C and 600 DEG C respectively,
After the insulation of each temperature section terminates, vacuum is respectively less than equal to 1x10-2Pa.1h, vacuum 6x10 are incubated at 660 DEG C-3During Pa, start
Compacting, pressing pressure 140MPa, single depression amount is controlled in 5mm, each dwell time 40min, when reaching maximum reduction, is protected
Pressure time 5h.After the car of billet containing steel mold after vacuum hotpressing goes steel mold, required for being processed into by machining processes
Parts.
Encapsulating material performance is as follows prepared by the present embodiment:Density 2.42g/cm3, parallel to graphite X-Y directions thermal conductivity
It is 280W/ (m.K) that thermal coefficient of expansion is 10.2 × 10-6/ K (27 DEG C~100 DEG C), bending strength reaches after solid solution aging
120MPa。
May be selected to use particle mean size in the present invention is the crystalline flake graphite of 100 mesh~32 mesh, and chemical nickel plating nickel layer thickness exists
Between 0.5-12um, alusil alloy atomized powder particle mean size is 800 mesh~200 mesh.In the present invention, crystalline flake graphite lamella direction
With pressing direction vertical distribution, in discontinuous arranged in parallel, alusil alloy is distributed in graphite flake layer gap to graphite flake, graphite flake with
Alusil alloy is in laminated construction.
Graphite and alusil alloy composite electron encapsulating material prepared by the inventive method, density:2.42~2.55g/cm3,
Parallel to graphite X-Y direction thermal conductivities between 240-280W/ (m.K), 27 DEG C~100 DEG C of thermal coefficient of expansion for 10.2~
13.9×10-6/ K, bending strength be 120~160MPa, the present invention obtained by electronic package material even tissue, with lightweight,
High heat conduction, low bulk, possess the combination properties such as some strength and easy processing, can be used as Electronic Packaging field related components material
Material.