CN105040106A - Preparation method of Cu6Sn5 intermetallic compound single crystal seeds - Google Patents

Abstract

The invention provides a preparation method of Cu6Sn5 intermetallic compound single crystal seeds, including preparation methods of (CuNi)6Sn5, (CuCo)6Sn5, (CuNiCo)6Sn5 and other reciprocal intermetallic compound seeds with structural similarity. The method comprises the following steps: a) selecting brazing filler metal; b) pre-treating the brazing filler metal; 3) preparing single crystal seeds through a super-saturated solution; and d) processing the single crystal seeds. Compared with the prior art, the preparation method provided by the invention has the advantages that when the preparation method is used for preparing single crystal seeds with special sizes, the cost is reduced, the efficiency is increased, and the quality is improved.

Description

A kind of Cu 6sn 5the preparation method of intermetallic compound monocrystalline seed

Technical field

The invention belongs to field of material technology, particularly a kind of Cu ₆sn ₅intermetallic compound and there is with it (CuNi) of structural similarity ₆sn ₅, (CuCo) ₆sn ₅, (CuNiCo) ₆sn ₅deng the preparation method of other reciprocity intermetallic compound monocrystalline seeds.

Background technology

Cu ₆sn ₅intermetallic compound is a kind of anisotropy Metallic Solids with silvery white metalluster, and its fusing point is 688.15K, and density is 8.270 ~ 8.448gcm ^-3, Young's modulus is 85 ~ 125GPa, and hardness is 4.5 ~ 6.5GPa, and specific conductivity is 2.38 ~ 5.71 × 10 ⁴scm, thermal conductivity is 0.341Wcm ^-1k ^-1, thermal expansivity is 12.2 ~ 16.3 × 10 ^-6k ^-1.In Electronic Packaging field, because copper base lead-in wire and tinbase interconnect the widespread use of solder, Cu ₆sn ₅the main interconnect interface product that intermetallic compound is formed after being shaped as copper tin metal metallurgy realizes interconnection structure to stablize and the principal security of electrically conducting.Especially along with electron device is towards the development in miniaturization, integrated and superpower direction, require that interconnect package size constantly reduces and packaging process temperature remains unchanged, therefore interface C u ₆sn ₅the generation volume volume ratio that accounts for interconnection solder joint entirety will significantly increase, be even fully formed with Cu ₆sn ₅the intermetallic compound solder joint of Xiang Weizhu.Consider Cu ₆sn ₅crystal has stronger anisotropy, and its c-axis direction has higher specific conductivity and a, b direction of principal axis has higher shearing resistance, be vertical placement direction and Cu that a, b axle is plane placement direction if therefore can be formed at interconnect interface place with c-axis ₆sn ₅single crystal structure, so very favourable for the target realizing machinery and electric property identical high reliability interconnection solder joint in high density packing system, the lifting of butt welding point bulk life time also has important practical and is worth.

But, the interface C u that generates of conventional tin-based solder and copper base pad metallurgical reaction ₆sn ₅grain orientation is completely random.Although the single crystal Cu base pad of specific orientation is for the Cu forming big area specific orientation to have document to show ₆sn ₅crystal grain has control action kou, but this " soft control " mode that is core with crystal nucleation-grow up to be difficult to realize real entirety consistent; In addition, even if realize completely single-orientated Cu ₆sn ₅crystal grain layer, the grain boundary defects district between neighboring die also can become starting position that pad melts destruction and cracking failure, thus jeopardizes the reliability of solder joint.Therefore, how to obtain and to mate with pad size and the controlled Cu of crystalline orientation ₆sn ₅monocrystalline seed has become the bottleneck of present stage solder joint interconnection technique.

On the other hand, Cu ₆sn ₅intermetallic compound or a kind of important cathode material for lithium ion battery.Consider the requirement to lithium cell energy density, power density, safety in utilization and cycle life aspect such as portable compact electronic product, Cu ₆sn ₅the volumetric expansion in tin and lithium alloyage process can be alleviated to a great extent as lithium ion battery negative material, there is good cyclical stability, and Cu ₆sn ₅the theoretical capacitance of storage of lithium ion battery negative material is up to 1900mAhcm ^-3, therefore the innovation of this material to cathode materials for lithium battery is significant.

But, present stage Cu ₆sn ₅lithium ion battery negative material mainly electrochemical process synthesis porous polycrystalline structure, as the porous current collector/tin-base alloy/carbon nano-tube combined electrode that Chinese patent CN10285131A is prepared by composite electroplating, and for example in Chinese patent CN103066252A, pass through the carbon-Cu that plating is formed ₆sn ₅alloy electrode.Although the porous C u of these chemosynthesis ₆sn ₅structure has the large advantage of specific surface area, but its polycrystalline structure must face the danger that grain-boundary crack even destroys fracture in circulating battery process, therefore how to prepare the nanometer Cu of high specific surface area ₆sn ₅monocrystalline seed becomes the key difficulties of its lithium ion battery negative material application.

According to above-mentioned analysis, no matter be to realize high performance interconnection solder joint, or in order to meet the cycle applications of lithium ion battery negative material, all need to solve how to realize specific dimensions Cu ₆sn ₅the preparation problem of monocrystalline seed.

Summary of the invention

The present invention solves prior art Problems existing by the following technical programs:

A kind of Cu ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, comprising: utilize supersaturation liquation to separate out proeutectic Cu ₆sn ₅the way of crystal grain prepares Cu ₆sn ₅monocrystalline, filters out the Cu of appropriate size afterwards with quartzy screen cloth ₆sn ₅single grain, by its sorting or the monocrystalline seed cutting into specific dimensions and demand further.

Wherein supersaturation liquation main component is tin copper, and can comprise a small amount of nickel, cobalt, silver, bismuth, rare earth element etc.For solder use mass concentration or volumetric molar concentration scope as shown in table 1.

Certain density supersaturation liquation is prepared by adding micrometer/nanometer copper powder and be cooled to specified temp in high temperature solution.Last according to liquation concentration, reaction times and Cu ₆sn ₅the reaction relation equation of growth size determines that quartzy screen cloth sieve gets Cu ₆sn ₅the Best Times of single grain.By the Cu of specific dimensions ₆sn ₅monocrystalline seed is classified according to application demand, as being applied to the micron level monocrystalline seed of solder joint interconnection aspect, is and for example applied to the Nano grade monocrystalline seed of lithium ion battery negative material aspect.

Table 1: supersaturation tin copper solder concentration

Described preparation method comprises: a) solder is selected; B) solder pre-treatment; C) monocrystalline seed is prepared by supersaturation liquation; D) monocrystalline seed processing.

A kind of Cu of the present invention ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, concrete steps comprise:

A), solder selects: choose suitable tin-based solder, as one or more of solder in Sn, Sn-Ag, Sn-Bi, Sn-Cu, Sn-In, Sn-Pb, Sn-Ag-Cu, Sn-Bi-Cu, Sn-In-Cu, Sn-Pb-Cu etc.

B), solder pre-treatment: by solder rod (block) sand for surface paper (as 1200#) polishing extremely without surface oxidation state; Suitable fritter is cut to cutting machine; Be soaked in the appropriate containers filling hydrochloride alcohol or nitric acid alcohol liquation (mass concentration is 1 ~ 10%), add corrosive fluid according to solder volume and the ratio of corrosion liquation 1:10, and ultrasonic cleaning 20min; Take out solder fritter, be positioned over and fill in the appropriate containers of distilled water, again ultrasonic cleaning 20min; After again taking out, dry up for subsequent use fast with cold wind.This step is mainly used in removing the zone of oxidation and organic pollutant that are attached to solder surface.

C), monocrystalline seed is prepared by supersaturation liquation: be positioned over by solder fritter in the heated molten bath such as the quartz crucible cleaned up, with possessing gas protecting function and with the heating unit of accurate temperature controlling, solder fritter being heated to its fusing, shielding gas is mainly nitrogen (also can with the rare gas element such as argon gas or helium); Continuous heating melt to 300 ~ 600 degree Celsius; A certain amount of Nano/micron copper powder (mass concentration 1.24%-39.12%) being joined in described solder (can be also other elements of 0-5% containing mass concentration, other elements are nickel, cobalt, silver, bismuth or rare earth element, as micro-/ nano nickel or cobalt powder, Ag, Bi, rare earth element), mechanical stirring be incubated (1 ~ 10h) until Addition ofelements dissolves completely under nitrogen atmosphere; Molten solder is slowly cooled to more than solder liquidus line 20 ~ 50 DEG C, held for some time (soaking time and required Cu ₆sn ₅grain-size is relevant, and typical soaking time is as 0.1h ~ 10h; Refer to the grain-size controlling curve and governing equation that provide subsequently); The precipitation product got in solder is sieved with the quartzy filtering net (as 1 ~ 100 μm) of specific dimensions; Products therefrom is soaked in the appropriate containers filling hydrochloride alcohol or nitric acid alcohol liquation (mass concentration 10 ~ 20%), etchant solution is added according to the ratio of soaking product and corrosive fluid volume ratio 1:10, and 10 minutes (this step is used for the remaining solder of wash products surface attachment) of ultrasonic cleaning; Take out product, be positioned over and fill in the appropriate containers of distilled water, again ultrasonic cleaning 10min; Again take out product and dry up fast with cold wind; With the quartzy filtering net (as 500nm ~ 100 μm) of specific dimensions, product is carried out more careful size classes, collect for subsequent use.This product is Cu ₆sn ₅monocrystalline (Fig. 1).

D), monocrystalline seed processing: by gained Cu ₆sn ₅monocrystalline is arranged in parallel according to long axis direction, in a rowly to process stacking for 10 ~ 20 single crystal rod together, so that be installed; At Cu ₆sn ₅the outermost of single crystal rod increases by two pieces of iron plates (thickness 0.5 ~ 1mm), so that the clamping of single crystal rod; The mode of low-speed WEDM is adopted to cut monocrystalline, working current 0.1 ~ 0.5A; Can according to parallel Cu during cutting ₆sn ₅monocrystalline long axis direction obtains and Cu ₆sn ₅(10-10) crystal plane be parallel section (as Fig. 2 a), also can according to vertical Cu ₆sn ₅monocrystalline long axis direction obtains and Cu ₆sn ₅(0002) section (as Fig. 2 b) of crystal plane be parallel; Product after cutting is put into alcohol liquation ultrasonic cleaning 1min, and cold wind is dried.This result is Cu ₆sn ₅monocrystalline seed.This cutting process method can realize the Cu of specific dimensions specific orientation preferably ₆sn ₅the preparation of monocrystalline seed, especially in processing speed, the precision sizing efficiency such as Billy's femto-second laser improves 1-10 doubly, and effective processed finished products rate can reach more than 60%.

The most important inventive point of the present invention relies on theoretical model design and realizes specific dimensions Cu ₆sn ₅the efficient preparation of monocrystalline.The method, by the concentration of adjusted saturated melt and reaction times, can effectively control specified particle diameter Cu ₆sn ₅the generating probability of monocrystalline, thus reduce follow-up cutting processing number of times, reduce difficulty of processing, improve material use efficiency and yield rate.

The present invention, by theory deduction, establishes and improves specific dimensions Cu ₆sn ₅the acquisition probability model of six side's bar-like single crystals, and the exactness of this model is confirmed by great many of experiments.It is as follows that theoretical model shifts process onto:

Due to Cu ₆sn ₅the initial nucleated time of crystal grain shorter (being less than 1s), so this time can ignore; And forming core terminate after by with the growth of crystal grain, if now Cu ₆sn ₅mutually the growth of six square rods is controlled by surface reaction, Gu the rate of migration v of so liquid/two-phase interface ^{l → η}can be expressed as:

$v^{L\→\mathrm{\η}}=\mathrm{\κ}\left(\frac{D_L}{\mathrm{RT}}\right)\frac{1}{\mathrm{\λ}}\mathrm{\ΔG}---\left(1\right)$

η in formula---Cu ₆sn ₅phase

L---solder liquid phase

κ---accommodation coeffieient, κ=10 during rough interfaces ^-2, κ=10 during smooth interface ^-4(zero dimension);

D _l---the spread coefficient (m of Cu in Sn ²s ^-1);

λ---Cu ₆sn ₅the interplanar distance (m) of phase;

Δ G---Cu ₆sn ₅motivating force (J) needed for phase grain growing.

But, consider that tin atom is a lot of soon in the interstitial diffusion speed of liquid phase self-diffusion speed ratio copper atom, so the rate of diffusion of copper atom may become restriction Cu ₆sn ₅the major obstacle of grain growing.Therefore according to the diffusion flux equilibrium conditions of copper: if the mass flux M ' at copper unit time arrival interface _arrivedbe not less than interface with speed v ^{l → η}mass flux M ' required for growth _needed, so this surface reaction is controlled by interface growth; If the mass flux that the copper unit time arrives interface is less than interface with speed v ^{l → η}mass flux required for growth, so this surface reaction is by copper diffusion control.Thus following formula can be obtained:

$M_{\mathrm{Needed}}^{\′}=S\·D_L{\left(\frac{{\∂x}_{\mathrm{Cu}}}{\∂\mathrm{\ρ}}\right)}_{\mathrm{\ρ}=r}---\left(2\right)$

$M_{\mathrm{Arrived}}^{\′}=\mathrm{dV}\·(x_{\mathrm{Cu}}^{\mathrm{\η}}-x_{\mathrm{Cu}}^{L/\mathrm{\η}})---\left(3\right)$

${\left(\frac{{\∂x}_{\mathrm{Cu}}}{\∂\mathrm{\ρ}}\right)}_{\mathrm{\ρ}=r}=\frac{x_{\mathrm{Cu}}^L-x_{\mathrm{Cu}}^{L/\mathrm{\η}}}{r}---\left(4\right)$

Surface-area (the m of S in formula---solid-liquid interface ²);

DV---Cu ₆sn ₅volume change (the m of phase ³);

ρ---Cu ₆sn ₅cu atomic percent distribution (at%m in the solder of phase front end ^-1).

By above 4 groups of formula, reaction times and Cu under finite concentration can be obtained ₆sn ₅the precise relation of grain growing size, and then the Cu that can improve single particle size ₆sn ₅the generating probability of monocrystalline.

This technology of preparing is also applicable to preparation and Cu ₆sn ₅the monocrystalline seed of the reciprocity intermetallic compound such as nickel, cobalt of structural similitude, as (CuNi) ₆sn ₅, (CuCo) ₆sn ₅, (CuNiCo) ₆sn ₅monocrystalline seed.Concrete grammar to be other elements of 0-5% containing mass concentration, other elements are nickel, cobalt, silver, bismuth or rare earth element, as nickel, cobalt micrometer/nanometer powder (as added solder mass concentration 0 ~ 5%) are mixed in micrometer/nanometer copper powder, and are dissolved in molten solder in heat-processed subsequently.

The present invention further provides a kind of cathode material for lithium ion battery, it is characterized in that, containing the Cu that aforementioned described preparation method prepares ₆sn ₅, (CuNi) ₆sn ₅, (CuCo) ₆sn ₅, (CuNiCo) ₆sn ₅deng intermetallic compound monocrystalline seed.

Wherein, term wt% is mass percent, at% atomic percent.

The present invention is relative to the advantage of prior art and beneficial effect:

1 the present invention from model foundation, fully take into account single crystal growing and element quality in melt supply between relation, thus increased substantially theoretical model prediction accuracy.And then by Theoretical Calculation, experiment is effectively instructed, thus accurately obtain the growth time of specific dimensions particle diameter, raise the efficiency and productive rate.

The supersaturation melt liberation method of 2 the present invention's application prepares single crystal process simple operations conveniently, and acquisition product efficiency is high and cost is low, and in addition, the simple environmental pollution of cleaning is less.

The monocrystalline excellent quality that 3 the present invention obtain and be easy to long-time preservation, cutting technique efficiency is processed higher than femto-second laser in addition, and material use efficiency can reach and uses 60% of solder quality.

Accompanying drawing explanation

Cu before accompanying drawing 1 screens ₆sn ₅monocrystalline

Cu after accompanying drawing 2 cuts ₆sn ₅monocrystalline: (a) cuts along parallel long axis direction; B () cuts along vertical long axis.

Accompanying drawing 3 tin copper binary phase diagram

Accompanying drawing 4 (a) Cu ₆sn ₅six side's single crystal rod shape appearance figures; B () is correlated with XRD diffracting spectrum, wherein redness is six side's single crystal rod spectral lines and the blue XRD spectral line for powder after grinding; (c) Cu ₆sn ₅the Kikuchi style collection of illustrative plates of grain surface.

Six square rod sizes and the mutual relationship of time under accompanying drawing 5 interface control growth conditions

Feed rate under accompanying drawing 6 diffusion control condition in the copper unit time and (a) half-width of demand and six square rods and the relation of (b) half between length.

The size of six square rods and the mutual relationship of time under accompanying drawing 7 (a) copper supply mechanism control; The b diameter of axle that () matching obtains is than the contrast of curve and experimental measurements.

Accompanying drawing 8 particle diameter is at the Cu of 0.8 ~ 1 μm ₆sn ₅monocrystalline cathode material for lithium ion battery

Accompanying drawing 9 particle diameter is at (CuNi) of 180 μm ₆sn ₅monocrystalline micron bar

Embodiment

Below in conjunction with Figure of description and embodiment, the invention will be further described:

The Cu of embodiment 120 ~ 40 micron grain size ₆sn ₅the preparation of intermetallic compound monocrystalline seed

30g copper nano is joined in 1kgSn0.7wt%Cu eutectic solder, be incubated 24h to ensure that copper nano fully dissolves 350 DEG C of mechanical stirring; Solder melt is cooled to 250 DEG C and insulation 10h; By 20 μm of quartzy screen clothes leaching solid phase from solder, by it at ice quenching-in water; By the hydrochloride alcohol liquation ultrasonic cleaning 10min of gained solid phase by mass concentration 10%, remove the solder of surface attachment, and clean products therefrom with distilled water; Remove with 40 μm of quartzy screen cloth sieves the macrobead not meeting dimensional requirement, will the powder collection of size be met.

Experimentation more than brief analysis is as follows.30g copper powder joins in 1kgSn1.3at%Cu eutectic solder (mass concentration being scaled atomic percent) melt, is the solder melt of 6.5at% in theory by acquisition copper atom concentration.By copper tin binary phase diagram known (Fig. 3), this concentration is 342 DEG C of saturated solder concentration of copper tin just, therefore when solder heat long-time to stir and after insulation, copper nano can melt completely in theory to 350 DEG C.Subsequently, when temperature is reduced to 250 DEG C, in solder liquation, the saturation solubility of copper will be reduced to 2.3at%, and now solder melt will become the supersaturation melt of copper, that is Cu ₆sn ₅temperature needed for phase homogeneous nucleation crosses cold and constitutional supercooling condition is all satisfied, and therefore from this solder, isolated solid phase should be Cu in theory ₆sn ₅phase, and be Cu ₆sn ₅phase homogeneous nucleation and by the product of steady-state growth gained.

Fig. 4 a is the Cu of 20 ~ 40 μm ₆sn ₅the typical pattern of intermetallic compound monocrystalline seed.Analyze (EDS) through X-ray energy dispersion spectrum and find that the stoichiometric number of this kind of club shaped structure is close to Cu ₆sn ₅, and also further demonstrate that this conclusion by X-ray diffraction spectrum analysis (XRD) subsequently.Obviously, the solid phase separated from this melt can be defined as Cu ₆sn ₅phase crystal grain.This crystal grain has six side's Rod-like shapes, and each side is bright and clean smooth.The top that it should be noted that this six square rod shape single crystal is accurate scallop shape.In addition, hollow structure is had in some barred body.

Discovery (as Fig. 4 b) is analyzed further according to X-ray diffraction spectrum, there is obvious preferred orientation in the surface of this six side's single crystal rod, and main Surface Texture is (10-10) (11-20), (21-31) and (30-30).Fig. 4 c is the six square rod side Kikuchi styles obtained by energy back scattering diffraction experiment (EBSD).Can determine according to Kikuchi pattern design, six side's bar-like single crystal sides are { 10-10} or { 11-20} two kinds of family of crystal planes.Analytical results in conjunction with XRD and EBSD can be determined, the side of six square rod shapes should be that those can form the crystal face of complete six prism structures, i.e. { 10-10} or { 11-20} family of crystal planes (and there is same zone axis [0001]), and the end face of six square rod shapes should be and lateral vertical or closely vertical surface, i.e. (0002) crystal face and nearly parallel crystal face thereof.Additionally by analysis of statistical results, by { the Cu that 10-10} crystal face is formed ₆sn ₅six square rod shape single grain are than by { it is many that 11-20} crystal face is formed, and therefore can think that six side's bar-like single crystals are (10-10) crystal face along the end face of long axis direction horizontal positioned, and long axis normal section is (0002) crystal face.

The Cu that embodiment 2 is obtained by above processing parameter ₆sn ₅the construction process of growth size Controlling model:

The foundation of this model is mainly for improving specific dimensions Cu ₆sn ₅the acquisition probability of six side's bar-like single crystals, reduces heat-up time and improves monocrystalline acquisition efficiency.

Due to Cu ₆sn ₅the grain nucleation time shorter (being less than 1s), so this time can ignore.If Cu ₆sn ₅the growth of six square rods is controlled by surface reaction mutually, so Cu ₆sn ₅{ 10-10} and the interface migration rate of end face (0002) 250 DEG C time can be expressed as in crystal grain side

$v_{{\left\{10\stackrel{\‾}{1}0\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}=1.88\×{10}^{-9}---\left(5\right)$

$v_{{\left\{0002\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}=2.72\×{10}^{-7}-\frac{2.11\×{10}^{-14}}{r_{{\left\{0002\right\}}_{\mathrm{\η}}}}---\left(6\right)$

What Fig. 5 represented is the six square rod half-widths (relation curve (red and black curve) of X or r) He half length (Y) and growth time obtained according to mobility integration.Due to the relation of geometry, dome radius r ₍₀₀₀₂₎also need the half-width X equaling side _{{ 10-10}}, therefore six square rod growth curves of interface control should represent for blue and red curve, and size control equation is as shown in formula (7) and (8).

$X_{{\left\{10\stackrel{\‾}{1}0\right\}}_{\mathrm{\η}}}=1.88\×{10}^{-9}t---\left(7\right)$

$Y_{{\left\{0002\right\}}_{\mathrm{\η}}}=2.72\×{10}^{-7}t-1.12\×{10}^{-5}\ln t+3.04\×{10}^{-5}---\left(8\right)$

According to formula (8), after 10h, the growth length of six square rods will reach 2cm, and this value is much larger than the measuring result of experiment.When considering 250 DEG C, the interstitial diffusion speed of the liquid phase self-diffusion speed ratio copper atom of tin atom is a lot of soon, so the rate of diffusion of copper atom may become restriction Cu ₆sn ₅the major obstacle grown mutually.Therefore according to formula (2)-(4), we can determine Cu further ₆sn ₅equilibrium relationship between grain growing and elements fed.

The feed rate that what Fig. 6 a and 6b represented respectively is under diffusion control condition in the copper unit time and the relation between the half-width of demand and six square rods and half length.Obviously, red copper demand curve and blue copper supply curve are at X _{{ 10-10}}=42.8 μm and Y ₍₀₀₀₂₎there occurs crossing during=669nm.This means no matter be length direction or width, the growth of six square rods is always subject to surface reaction in the initial stage and controls, and when six square rods dimensional growth to a certain extent after the feed rate of copper will be less than needed for its growth, at this time grain growing will be subject to copper diffusion control.

In order to obtain six clear and definite square rod growth kinetics model, above two kinds of growth control mechanisms being unified, sets up copper dispenser device simulation.When supply is sufficient, surface reaction is by surface reaction mechanism control.When copper atom supply is inadequate, surface reaction is by diffusion control.Thus following formula can be obtained:

$v_{{\left\{10\stackrel{\‾}{1}0\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}=\frac{{\mathrm{dX}}_{{\left\{10\stackrel{\‾}{1}0\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}}{\mathrm{dt}}=\left\{\begin{array}{cc}1.88\×{10}^{-9}& I:41\≤t\≤22764\\ 8.049\×{10}^{-9}/X_{{\left\{10\stackrel{\‾}{1}0\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}& \mathrm{II}:t\≥22765\end{array}\right.---\left(9\right)$

$v_{{\left\{0002\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}=\frac{{\mathrm{dr}}_{{\left\{0002\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}}{\mathrm{dt}}\left\{\begin{array}{cc}2.72\×{10}^{-7}-\frac{2.11\×{10}^{-14}}{1.88\×{10}^{-9}t}& I:41\≤t\≤348\\ \frac{1.61\×{10}^{-13}}{1.88\×{10}^{-9}t}& \mathrm{II}:349\≤t\≤22764\\ \frac{1.61\×{10}^{-13}}{r_{{\left\{0002\right\}}_{\mathrm{\η}}}^{L\→\mathrm{\η}}}& \mathrm{III}:t\≥22765\end{array}\right.---\left(10\right)$

Fig. 7 a is the size of six square rods and the mutual relationship of time under copper supply mechanism control.The 41s reacting initial is interior for closing on the formation of nucleus.After 41s, by surface reaction mechanism control, it grows the size of six square rods, at this time because the feed rate of the limited copper of size of six square rods is enough to meet needed for its growth.After growth time reaches 349s, the dome place copper feed rate of six square rods starts cannot meet needed for interface growth, and now dome surface starts to control its growth by the flooding mechanism of copper.When growth time reaches 22764s, the width of six square rods also starts to control by the flooding mechanism of copper, and be meanwhile the restricted condition of meeting geometric structure, dome surface also can adjust thereupon.Therefore, there are two kinds of growth phases in the size of six square rods and the relation of growth time, and presents three kinds of growth phases in the direction of the width in the longitudinal direction.

After it should be noted that 10h, the half-width of six square rods and the maximum value of half length are 58.3 μm and 440 μm respectively, and the result that this and experimental observation are arrived is coincide good.In addition, the diameter of axle comparing theory deduction can find than data (as Fig. 7 b) than the six square rod diameters of axle of curve with experiment measuring, also very similar between the two.Occur that the maximum diameter of axle ratio of six square rods occurs in X=872nm place in theory, and maximum diameter of axle ratio is 96.7, and finally stable diameter of axle ratio is close to 7.54.

According to above technical arrangement plan heat-up time, can obtain a large amount of width when heating 2.96 ~ 5.9h be 20 ~ 40 μm, and length is six side's bar-like single crystal Cu of 200 ~ 1000 μm ₆sn ₅crystal grain (probability density 77.4%).This by building governing equation thus determining Cu ₆sn ₅the method of grain growing size, not only significantly can reduce the reaction times needed for single crystal growing, also can improve the number obtaining single size crystal grain simultaneously, reduce Linear cut number of times subsequently.Finally, by a simple step cutting, the three-dimensional high-density encapsulation solder joint application that interconnection window is 20 ~ 40 μm can be realized.

The Cu of embodiment 30.8 ~ 1 micron grain size ₆sn ₅prepared by monocrystalline cathode material for lithium ion battery

30g copper nano is joined in 1kgSn0.7wt%Cu eutectic solder, be incubated 24h to ensure that copper nano fully dissolves 350 DEG C of mechanical stirring; Solder melt is cooled to 250 DEG C and insulation 7.09 ~ 8.86min; By 0.5 μm of quartzy screen cloth leaching solid phase from solder, by it at ice quenching-in water; By the hydrochloride alcohol liquation ultrasonic cleaning 10min of gained solid phase by mass concentration 10%, remove the solder of surface attachment, and clean products therefrom with distilled water; Remove with 1 μm of quartzy screen cloth sieve the macrobead not meeting dimensional requirement, will the powder collection of size be met.Gains as shown in Figure 8, be length at 20 ~ 80 μm and particle diameter at the Cu of 0.8 ~ 1 μm ₆sn ₅crystal grain.

The Cu of embodiment 4 containing elements such as Ni, Co ₆sn ₅the preparation of intermetallic compound monocrystalline seed

Cu ₆sn ₅there are solid-state phase changes in intermetallic compound, namely by the close-packed hexagonal structure η-Cu of high temperature state between 186 ~ 189 DEG C ₆sn ₅(P6 ₃/ mmc) change the monocline η '-Cu of cold state into ₆sn ₅(C2/c), and along with the change Cu of crystalline network ₆sn ₅the volumetric expansion of 2.15% will be there is in phase structure cell.Consider in-service that the volumetric expansion producing more than 2% produces serious problem of stress concentration by interface, if therefore this solid-state phase changes generation will probably to Cu ₆sn ₅the reliability of monocrystalline seed causes serious threat.

According to people's reports such as California, USA university Los Angeles branch school K.N.Tu, η-Cu in the interconnect interface of quenching state ₆sn ₅can at room temperature retain for a long time.The people such as Univ Helsinki Finland T.Laurila also confirm the restriction due to interconnection solder joint cooling time, η-Cu ₆sn ₅to η '-Cu ₆sn ₅solid-state phase changes be usually difficult to realize completely because transformation time is not enough, thus interface Cu under causing room temperature ₆sn ₅crystal grain is made up of two kinds of crystalline networks.In addition, the result according to X ray diffracting spectrum in Fig. 4 b confirms, six side's bar-like single crystal Cu that this technology is prepared ₆sn ₅really there is η-Cu in crystal grain ₆sn ₅phase structure.

Find according to research, add nickel in right amount, cobalt element can effectively improve η-Cu ₆sn ₅structural reliability, thus eliminate because of Cu ₆sn ₅there is the monocrystalline seed interfacial failure that solid-state phase changes cause.Therefore, this technology only need adjust the kind adding nano powder in the single crystal preparation stage, namely add a small amount of nickel, cobalt element (mass ratio 0 ~ 5%) one or both effectively can prepare Cu containing nickel, cobalt element ₆sn ₅reciprocity intermetallic compound.

34.17 grams of nickel nano powders are joined in the pure Sn solder of 1kg, be incubated 24 hours to ensure that copper nano fully dissolves 350 degrees Celsius of mechanical stirring; Solder melt is cooled to 250 degrees Celsius and insulation 29.5 ~ 32.1h; By 150 micron quartz screen clothes leaching solid phase from solder, by it at ice quenching-in water; By the hydrochloride alcohol liquation ultrasonic cleaning 10 minute of gained solid phase by mass concentration 10%, remove the solder of surface attachment, and clean products therefrom with distilled water; Remove with 180 micron quartz screen cloth sieves the macrobead not meeting dimensional requirement, will the powder collection of size be met.

Fig. 9 is (CuNi) of 150 ~ 180 μm of particle diameters prepared by this technology ₆sn ₅reciprocity intermetallic compound, this structure remains six side's club shaped structures as shown in the figure, with Cu ₆sn ₅it is slightly coarse that bar-like single crystal compares its surface.

Above content is in conjunction with concrete preferred implementation further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, some simple deduction or replace can also be made, all should be considered as belonging to protection scope of the present invention.

Claims (10)

1. a Cu ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, is characterized in that, comprising: utilize supersaturation liquation to separate out proeutectic Cu ₆sn ₅the way of crystal grain prepares Cu ₆sn ₅monocrystalline, filters out the Cu of appropriate size afterwards with quartzy screen cloth ₆sn ₅single grain, by its sorting or the monocrystalline seed cutting into specific dimensions and demand further.

2. a kind of Cu according to claim 1 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, is characterized in that, wherein, supersaturation liquation main component is tin copper, and the quality of tin and copper is 60.88%-98.76%:1.24%-39.12% than concentration.

3. a kind of Cu according to claim 2 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, is characterized in that, wherein, it is other elements of 0-5% that supersaturation liquation also contains mass concentration, and other elements are nickel, cobalt, silver, bismuth or rare earth element.

4. a kind of Cu according to the arbitrary claim of claim 1-3 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, is characterized in that, described preparation method comprises: a) solder is selected; B) solder pre-treatment; C) monocrystalline seed is prepared by supersaturation liquation; D) monocrystalline seed processing.

5. a kind of Cu according to claim 4 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, it is characterized in that, described step a) solder chooses suitable tin-based solder, as one or more of solder in Sn, Sn-Ag, Sn-Bi, Sn-Cu, Sn-In, Sn-Pb, Sn-Ag-Cu, Sn-Bi-Cu, Sn-In-Cu, Sn-Pb-Cu etc.

6. a kind of Cu according to claim 4 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, is characterized in that, described step b) solder pre-treatment: by step, a) solder rod or block sand for surface paper are polished extremely without surface oxidation state; Suitable fritter is cut to cutting machine; Being soaked in and filling mass concentration is in the appropriate containers of 1 ~ 10% hydrochloride alcohol liquation or nitric acid alcohol liquation, be that 1:10 adds hydrochloride alcohol liquation or nitric acid alcohol liquation according to solder volume and hydrochloride alcohol liquation or nitric acid alcohol liquation ratio, and ultrasonic cleaning 20min; Take out solder fritter, be positioned over and fill in the appropriate containers of distilled water, again ultrasonic cleaning 20min; After again taking out, dry up for subsequent use fast with cold wind.

7. a kind of Cu according to claim 4 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, it is characterized in that, described step c) prepare monocrystalline seed by supersaturation liquation: by step b) solder fritter is positioned in the heated molten bath such as the quartz crucible cleaned up, with possessing gas protecting function and with the heating unit of accurate temperature controlling, solder fritter being heated to its fusing, shielding gas is mainly the rare gas elementes such as nitrogen, argon gas or helium; Continuous heating melt to 300 ~ 600 degree Celsius; Be 60.88%-98.76%:1.24%-39.12%:0-5% according to the quality of tin, copper and other elements than concentration, Micron Copper Powder and other elements are joined in described solder, other elements are nickel, cobalt, silver, bismuth or rare earth element, mechanical stirring be incubated 1 ~ 10h until Addition ofelements dissolves completely under nitrogen atmosphere, described slowly cools to more than solder liquidus line 20 ~ 50 DEG C, held for some time 0.1h ~ 10h by molten solder; The precipitation product in solder is got with the quartz filtration mesh screen of 1 ~ 100 μm of size.

8. a kind of Cu according to claim 7 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, it is characterized in that, being soaked in by products therefrom further and filling mass concentration is in the appropriate containers of 10 ~ 20% hydrochloride alcohol liquations or nitric acid alcohol, adds with liquor capacity according to immersion product than 1:10, and ultrasonic cleaning 10 minutes; Take out product, be positioned over and fill in the appropriate containers of distilled water, again ultrasonic cleaning 10min; Again take out product and dry up fast with cold wind; With the quartzy filtering net of size 500nm ~ 100 μm, product is carried out more careful size classes, collect for subsequent use.

9. a kind of Cu according to claim 4 ₆sn ₅the preparation method of intermetallic compound monocrystalline seed, is characterized in that, described steps d) processing of monocrystalline seed: by step c) gained Cu ₆sn ₅monocrystalline is arranged in parallel according to long axis direction, in a rowly to process stacking for 10 ~ 20 single crystal rod together, so that be installed; At Cu ₆sn ₅the outermost of single crystal rod increases by two pieces of thickness 0.5 ~ 1mm iron plates so that the clamping of single crystal rod; The mode of low-speed WEDM is adopted to cut monocrystalline, working current 0.1 ~ 0.5A; Can according to parallel Cu during cutting ₆sn ₅monocrystalline long axis direction obtains and Cu ₆sn ₅the section of crystal plane be parallel, also can according to vertical Cu ₆sn ₅monocrystalline long axis direction obtains and Cu ₆sn ₅the section of crystal plane be parallel; Product after cutting is put into alcohol liquation ultrasonic cleaning 1min, and cold wind is dried.

10. a cathode material for lithium ion battery, is characterized in that, containing the Cu that preparation method described in the arbitrary claim of claim 1-9 prepares ₆sn ₅intermetallic compound monocrystalline seed.