CN103521910A

CN103521910A - Method for target material component welding

Info

Publication number: CN103521910A
Application number: CN201210232834.6A
Authority: CN
Inventors: 姚力军; 相原俊夫; 大岩一彦; 潘杰; 王学泽; 李超
Original assignee: Ningbo Jiangfeng Electronic Material Co Ltd
Current assignee: Ningbo Jiangfeng Electronic Material Co Ltd
Priority date: 2012-07-05
Filing date: 2012-07-05
Publication date: 2014-01-22

Abstract

The invention provides a method for target material component welding. The method comprises the following steps that an aluminum target material and a copper back board are provided; silver is plated on a face to be welded of the aluminum target material to form a silver middle layer; the aluminum target material with the silver middle layer and the copper back board are placed in a vacuum bag, the silver middle layer is located between the aluminum target material and the copper back board, and the vacuum bag is arranged in a welding device; the hot isostatic pressure technology is used for welding the aluminum target material with the silver middle layer and the copper back board together to form a target material component; after welding is completed, the vacuum bag is cooled and removed, so that the target material component is obtained. The method is high in welding efficiency, the formed target material component is good in welding binding rate, high in welding strength and small in deformation, the internal organization structure of the aluminum target material in the target material component meets the sputtering requirement, and therefore requirements for long-time stable production and using of target materials can be met.

Description

The welding method of target material assembly

Technical field

The present invention relates to semiconductor sputtering target material and manufacture field, relate in particular to a kind of welding method of target material assembly.

Background technology

In semi-conductor industry, target material assembly is to consist of the backboard that meets the target of sputtering performance and can be combined and have some strength with described target.Backboard can be assembled in sputter base station and play a supporting role at described target material assembly, and has the effect of conduction heat.

In sputter procedure, the residing working environment of target material assembly is more severe.The residing environment temperature of target material assembly is higher, for example 300 ° of C to 600 ° of C; In addition, a side blow of target material assembly is cold by force with cooling water, and opposite side is in 10 ^-9under the high vacuum environment of Pa, relative two sides at target material assembly are formed with huge pressure differential thus; Have, target material assembly is in high voltage electric field, magnetic field again, is subject to the bombardment of various particles.Under rugged environment like this, if the weld strength in target material assembly between target and backboard is poor, to cause target material assembly under heating condition, be out of shape, ftracture and come off mutually with the backboard of combination, make sputter cannot reach the uniform effect of sputter, also may cause damage to sputter base station simultaneously.

Therefore, need to select a kind of effective welding manner, so that the weld strength between target and backboard meets the demand of practical application.At publication number, be open day of CN1986133A(: the information that can also find the more welding method about target and backboard in Chinese patent literature on June 27th, 2007).

For the target material assembly of aluminium target and copper backboard formation, because aluminium and copper are easily oxidized in air, low by existing diffusion welding method welding efficiency, solder bond rate variance, the weld strength of the target material assembly forming are low, deflection is large and target material assembly in the internal organizational structure of aluminium target do not meet sputter requirement, therefore can not meet steady in a long-term production and the needs of use target.

Summary of the invention

The technical problem to be solved in the present invention is that when aluminium target and copper backboard are welded together by existing welding method, welding efficiency is low, solder bond rate variance, the weld strength of the target material assembly forming are low, deflection is large and target material assembly in the internal organizational structure of aluminium target do not meet sputter requirement, therefore can not meet steady in a long-term production and the needs of use target material assembly.

For solving the problems of the technologies described above, the invention provides the welding method of a kind of aluminium target and copper backboard, comprise following methods step:

Aluminium target and copper backboard are provided;

The silver-colored intermediate layer of silver-plated formation in the junction to be welded of described aluminium target;

The aluminium target, the copper backboard that are formed with described silver-colored intermediate layer are placed in vacuum canning and make described silver-colored intermediate layer between described aluminium target and copper backboard, described vacuum canning is placed in welding equipment;

Utilize heat and other static pressuring processes that described aluminium target, the copper backboard that is formed with silver-colored intermediate layer welded together to form target material assembly;

After having welded, described vacuum canning is carried out cooling, remove described vacuum canning to obtain described target material assembly.

Optionally, in the junction to be welded of described aluminium target, silver-plated method is chemical plating or plating.

Optionally, the chemical plating fluid that described chemical plating adopts comprises silver salt solution and reductant solution, and described silver salt solution comprises silver nitrate 55g/L ~ 65g/L, NaOH 40g/L ~ 45g/L and ammoniacal liquor 40g/L ~ 50g/L; Described reductant solution comprises glucose (C ₆h ₁₂o ₆) 40g/L ~ 30g/L, tartaric acid (C ₄h ₆o ₆) 3g/L ~ 6g/L and ethanol (C ₂h ₅oH) 90g/L ~ 110g/L, the volume ratio of described silver salt solution and reductant solution is 1:1, and the temperature of chemical plating fluid is 15 ℃ ~ 20 ℃, and the pH value of chemical plating fluid is 9.0 ~ 12.0, and the plating time of described chemical plating is 60min ~ 80min.

Optionally, the electroplate liquid of described plating employing comprises silver chlorate (AgCl) 33g/L ~ 39g/L, potassium cyanide (KCN) 40g/L ~ 70g/L and potash (K ₂cO ₃) 10g/L ~ 15g/L, the temperature of described electroplate liquid is 15 ℃ ~ 20 ℃, described cathode-current density is 0.25A/dm ²~ 0.5A/dm ², the plating time of described plating is 50min ~ 70min.

Optionally, the thickness in described silver-colored intermediate layer is 10 μ m ~ 15 μ m.

Optionally, the described heat and other static pressuring processes that utilizes comprises being formed with the aluminium target in silver-colored intermediate layer and step that copper backboard welds together:

The ambient temperature that makes described vacuum canning is 300 ℃ ~ 350 ℃, and external environment condition pressure is more than or equal to 90Mpa;

The described vacuum canning being positioned under described environment temperature and environmental stress is incubated to 2 hours ~ 4 hours, so that the described aluminium target and the copper backboard that are formed with silver-colored intermediate layer are welded together.

Optionally, the welding of aluminum that described vacuum canning is is 2.5mm ~ 3.0mm by thickness forms, and after described aluminium target, copper backboard are placed in vacuum canning, is evacuated to 2 * 10 to vacuum canning described in major general ^-3pa, then by described vacuum canning sealing.

Optionally, the process that described vacuum canning vacuumizes is the process that limit heating edge vacuumizes, and the temperature of described heating is 250 ℃ ~ 350 ℃.

Optionally, in described junction to be welded, before the step in the silver-colored intermediate layer of silver-plated formation, described junction to be welded is carried out to pretreatment, described pretreatment comprises the following steps:

Described junction to be welded is carried out to blasting treatment, increase the roughness of described junction to be welded;

Junction to be welded after blasting treatment is carried out to activation processing, make described mask to be welded have activation energy;

Junction to be welded after activation processing is carried out to pickling, remove for the first time the oxide-film in described junction to be welded;

Junction to be welded after pickling processes is carried out to cleaning treatment, remove residual pickle in described junction to be welded;

Junction to be welded after cleaning is soaked to zinc and process, remove for the second time the oxide-film in described junction to be welded.

Optionally, form the step in silver-colored intermediate layer in the junction to be welded of described aluminium target after, the step that the aluminium target, the copper backboard that are formed with described silver-colored intermediate layer are placed in vacuum canning also comprises step before:

Adopt hyperacoustic method to clean being formed with aluminium target and the copper backboard in described silver-colored intermediate layer;

After cleaning, to being formed with aluminium target and the copper backboard in described silver-colored intermediate layer, carry out vacuum drying.

Compared with prior art, the advantage of technical scheme of the present invention is:

By setting up silver-colored intermediate layer and vacuum canning is set between aluminium target and copper backboard, recycling heat and other static pressuring processes effectively welds together aluminium target and copper backboard.First, silver-colored intermediate layer atom more easily diffuses in aluminium target and copper backboard, makes the welding efficiency of whole welding process higher; Secondly, welding stress be avoided or be reduced in silver-colored intermediate layer can also, makes the target material assembly of formation not yielding; And the whole welding process that is arranged so that of vacuum canning is to carry out under vacuum environment, can prevent that the surface of aluminium target and copper backboard is oxidized, can improve solder bond rate and weld strength in target material assembly.

Further, in existing diffusion technology for welding, the welding temperature of aluminium target and copper backboard is higher, and for being more than or equal to 500 ° of C, with respect to existing Diffusion Welding temperature, welding temperature of the present invention is lower, is 300 ℃ ~ 350 ℃.Like this can be so that the inner crystal grain of the aluminium target in target material assembly be not easy recrystallization occurs and grows up, the crystallite dimension of the aluminium target in this target material assembly is less than 100 μ m, most of grain orientation is crystal orientation (200), such internal organizational structure just meets sputter requirement, but also has good sputter effect.The target material assembly serviceability temperature that the present invention forms can reach more than 600 ℃, and the phenomenon that target material assembly can not come off under this hot conditions can meet the needs of producing and using target steady in a long-term.

Accompanying drawing explanation

Fig. 1 is the welding method flow chart of target material assembly of the welding method embodiment of target material assembly of the present invention;

Fig. 2 is the structural representation of aluminium target of the welding method embodiment of target material assembly of the present invention;

Fig. 3 is the structural representation of copper backboard of the welding method embodiment of target material assembly of the present invention;

Fig. 4 is the schematic diagram in the silver-plated intermediate layer of method of employing chemical plating of the welding method embodiment mono-of target material assembly of the present invention;

Fig. 5 is the structural representation of target material assembly part of the welding method embodiment of target material assembly of the present invention;

Fig. 6 is that aluminium target, copper backboard that the surface of the welding method embodiment of target material assembly of the present invention is formed with intermediate layer are placed in the schematic diagram while carrying out heat and other static pressuring processes in vacuum canning together;

Fig. 7 is the schematic diagram in the silver-plated intermediate layer of employing electric plating method of the welding method embodiment bis-of target material assembly of the present invention.

The specific embodiment

Solder bond rate variance, the weld strength of the target material assembly that existing welding method is welded together to form aluminium target and copper backboard are low, deflection is large and target material assembly in the internal organizational structure of aluminium target do not meet sputter requirement, therefore can not meet the needs of producing and using target steady in a long-term.

The present inventor learns existing diffusion technology for welding analysis, and for aluminium target, because aluminium is easy oxidized metal in air, so that the atom between aluminium target and copper backboard can not effectively spread.And the welding stress between aluminium target and copper backboard is larger, make aluminium target and copper backboard deformation rate in welding process higher, the solder bond rate variance of the target material assembly of formation, weld strength are poor.Moreover in existing diffusion technology for welding, welding temperature is higher, be more than or equal to 500 ° of C, make the inner crystal grain of aluminium target recrystallization occur and grow up, crystal orientation is also uncontrollable, the sputtering performance of the target material assembly forming is poor, is specially and affects sputter rate and thin film deposition quality.

Inventor through creative work, has obtained the welding method of a kind of aluminium target and copper backboard, can avoid above-mentioned technical problem, please refer to Fig. 1, and Fig. 1 is the welding method flow chart of target material assembly of the welding method embodiment of target material assembly of the present invention.Specifically comprise the following steps:

Execution step S11, provides aluminium target and copper backboard;

Execution step S12, the silver-colored intermediate layer of silver-plated formation in the junction to be welded of described aluminium target;

Execution step S13, is placed in vacuum canning by the aluminium target, the copper backboard that are formed with described silver-colored intermediate layer and makes described silver-colored intermediate layer between described aluminium target and copper backboard, and described vacuum canning is placed in welding equipment;

Execution step S14, utilizes heat and other static pressuring processes that described aluminium target, the copper backboard that is formed with silver-colored intermediate layer welded together to form target material assembly;

Execution step S15, after having welded, carries out coolingly to described vacuum canning, remove described vacuum canning to obtain described target material assembly.

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in detail.Set forth in the following description a lot of details so that fully understand the present invention, but the present invention can also adopt other to be different from alternate manner described here, implement, so the present invention has not been subject to the restriction of following public specific embodiment.

Embodiment mono-

First referring to figs. 2 and 3, the step S11 in execution graph 1, provides aluminium target 11 and copper backboard 12.

Please continue to refer to Fig. 2, in the present embodiment, the purity of aluminium target 11 is at least 99.9995%.According to the actual requirement of applied environment, sputtering equipment, the shape of aluminium target 11 can be cylinder, cuboid, square, cone, cross section is any the cylinder in annular, triangle or other analogous shapes (comprising regular shape and irregularly shaped), and preferred version is cylinder.The diameter dimension of aluminium target 11 for adding the allowance of 2mm ~ 5mm in design size, and gauge for adding the allowance of 1mm ~ 3mm in design size.The object that allowance is set is in follow-up machining, to provide well-to-do processing space to obtain satisfactory target material assembly for aluminium target 11.

Please continue to refer to Fig. 3, for aluminium target 11, why select copper backboard 12 to form target material assembly, because copper product has sufficient intensity, and heat conduction, electric conductivity are also higher, the better performances of the target material assembly of formation.According to the actual requirement of applied environment, sputtering equipment, the shape of described copper backboard 12 can be cylinder, cuboid, square, cross section is any the cylinder in annular, triangle or other analogous shapes (comprising regular shape and irregularly shaped), and preferred version is cylinder.Described copper backboard 12 has the groove 121 that holds aluminium target 11, and, in the present embodiment, the bottom surface of described groove 121 is circular, and groove 121 base diameters are identical with the diameter of aluminium target 11.The diameter of copper backboard 12 can add the surplus of 2mm ~ 5mm in design size, and thickness for adding the surplus of 1mm ~ 3mm in target size.The object that increases surplus is to provide well-to-do processing space to forming target material assembly procedure of processing afterwards.

Then, in conjunction with referring to figs. 2 and 5, the step S12 in execution graph 1, the silver-colored intermediate layer 13 of silver-plated formation on the junction I to be welded of described aluminium target 11.

Please continue to refer to Fig. 2, described aluminium target 11 comprises junction I to be welded, sputter face and side IV.Described junction I to be welded is the face in the silver-colored intermediate layer of the silver-plated formation of aluminium target 11, and sputter face is the face relative with junction I to be welded, and side IV is the surface between junction I to be welded and sputter face.

Incorporated by reference to reference to figure 2, Fig. 3 and Fig. 5, in order to improve the Weldability of aluminium target 11 and copper backboard 12 in follow-up welding procedure, can in the junction to be welded of aluminium target 11, form silver-colored intermediate layer 13 by I.Inventor's discovery, when aluminium target 11 and copper backboard 12 are welded together, the intermediate layer of ag material energy while and aluminium target, copper backboard carry out better combination to increase solder bond rate, the weld strength between aluminium target 11 and copper backboard 12.The thickness in silver intermediate layer 13 is 10 μ m ~ 15 μ m.If silver intermediate layer 13 is too thin, in welding process, easily occur solder skip, and self fracture strength in too thin silver-colored intermediate layer 13 is low; If silver intermediate layer 13 is too thick, aluminium target 11 and copper backboard 12 shapes are all fixing, and the target material assembly of follow-up formation is too thick and install less than on sputter base station.

Because the thickness in silver-colored intermediate layer 13 only has 10 μ m ~ 15 μ m, so adopt silver-plated method to form silver-colored intermediate layer 13 at the junction I to be welded of aluminium target 11, and adopt machining to form certain thickness silver-colored intermediate layer, and then the silver-colored intermediate layer of machining formation is positioned between aluminium target 11 and copper backboard 12 to bed thickness in the middle of the silver that the silver-colored intermediate layer that such method forms forms than the former silver-plated method.In the present embodiment, adopt the method for chemical plating in the silver-colored intermediate layer 13 of the silver-plated formation of the junction I to be welded of aluminium target 11.

Before the step in the silver-colored intermediate layer 13 of the silver-plated formation of the junction I to be welded of described aluminium target 11, the junction I to be welded of described aluminium target 11 is carried out to pretreatment, described pretreatment comprises step:

Execution step S121, carries out blasting treatment to the junction to be welded of aluminium target, increases the roughness of the junction to be welded of described aluminium target;

Execution step S122, carries out activation processing to the junction to be welded of the aluminium target after blasting treatment, makes the mask to be welded of the aluminium target after described blasting treatment have activation energy;

Execution step S123, carries out pickling to the junction to be welded of the aluminium target after activation processing, removes for the first time the oxide-film of the junction to be welded of the aluminium target after described activation processing;

Execution step S124, carries out cleaning treatment to the junction to be welded of the aluminium target after pickling processes, removes the junction residual acid washing lotion to be welded of the aluminium target after described pickling processes;

Execution step S125, soaks zinc to the junction to be welded of the aluminium target after cleaning and processes, and removes for the second time the oxide-film of the junction to be welded of the aluminium target after described cleaning.

Please continue to refer to Fig. 2, the junction I to be welded of aluminium target 11 is carried out to pretreatment below and be elaborated.

In step S121, the effect of the junction I to be welded of aluminium target 11 being carried out to blasting treatment is the roughness that increases the junction I to be welded of aluminium target 11, silver-colored intermediate layer 13 can be better plated in the junction to be welded of aluminium target 11, and the adhesion that improves the junction I to be welded of silver-colored intermediate layer 13 and aluminium target 11, makes silver-colored intermediate layer 13 be not easy to come off from the junction I to be welded of aluminium target 11.

The principal element that affects blasting treatment quality has: sand material, sand grains size, air pressure, spray angle, jet length.The variation of any one parameter all can affect the effect of blasting craft to some extent, wherein for sand material, sand grains size, air pressure, is even more important.

In the present embodiment, 125 flint glass F pearls are as the sand grains using.Why use 125 flint glass F pearls, relevant with the hardness of aluminium target 11, also relevant with follow-up roughness after the junction I sandblast to be welded of aluminium target 11, in the present embodiment, the junction I roughness Ra requirement to be welded of aluminium target 11 is 10 μ m ~ 15 μ m.Pour 125 flint glass F pearls into sand-blasting machine, sand-blasting machine air pressure scope control is at 0.3MPa ~ 0.4MPa, if air pressure is greater than 0.4MPa, the power of sandblast is too large, the roughness of the junction I to be welded of aluminium target 11 is strengthened, affect the adhesion of the junction I to be welded of follow-up silver-colored intermediate layer 13 and aluminium target.If air pressure is less than 0.3MPa, being short of power of sandblast, makes the roughness of junction I to be welded of aluminium target 11 not enough, affects equally the adhesion of follow-up silver-colored intermediate layer 13 and the junction I to be welded of aluminium target 11.In the present embodiment, the nozzle of the sand-blasting gun on sand-blasting machine is 150mm ~ 200mm to the distance of the junction I to be welded of aluminium target 11, the angle that nozzle sprays the direction of 125 flint glass F pearls and the junction I to be welded of aluminium target 11 is non-perpendicular angle relation,, except 90 degree, other angle that is less than 180 degree all can, preferred angle scope is 70 degree ~ 80 degree, the uniformity of sandblast and coverage are more guaranteed like this.After blasting treatment, at the junction I to be welded of aluminium target 11, forming mean depth is the rough layer of 10 μ m ~ 15 μ m.Further optimally, after blasting craft, can also clean the junction I to be welded of aluminium target 11, such as adopting deionized water or pure water to clean, scavenging period is 1min ~ 2min.

For step S122, inventor finds, the junction I to be welded of aluminium target 11 is carried out to activation processing can make follow-up Electroless Silver Plating carry out smoothly, because, the junction I to be welded of aluminium target 11 is carried out to the activation energy that activation processing has increased the junction I to be welded of aluminium target 11, the reactivity of the junction I to be welded of aluminium target 11 is strengthened, be increased on the junction I to be welded of aluminium target 11 and carry out the speed that chemical silvering forms silver-colored intermediate layer 13, avoid silver-colored intermediate layer 13 to be combined not firm serious problems with the junction I to be welded of aluminium target 11.The selection of activator is relevant with aluminium target 11 materials, if can increase the junction I to be welded of aluminium target 11 activation energy, make the activator that the reactivity of the junction I to be welded of aluminium target 11 strengthens can.

In the present embodiment, the salpeter solution that the activator that the junction I activation processing to be welded of aluminium target 11 is adopted is 500ml/L, soak time is 5s ~ 10s.If soak time is less than 5s, activator does not play the effect of activation completely; If soak time is greater than 10s, salpeter solution can corrode the junction I to be welded of aluminium target 11.

Through above-mentioned activation processing, in subsequent chemistry depositing process, can make silver-colored intermediate layer 13 better be plated on aluminium target 11 junction I to be welded.

Easily in air, there is oxidation reaction in aluminium target 11, surface at aluminium target 11 forms oxide-film, in step S122, although the junction I to be welded of aluminium target 11 is carried out to activation processing, excite the activation energy of aluminium target 11, but do not removed the oxide-film on the junction I to be welded of aluminium target 11.Therefore, execution needs step S123, step S124 and step S125, the junction I to be welded of the aluminium target 11 after activation processing is carried out to pickling processes and soak zinc and process, thoroughly to remove the oxide-film of aluminium target 11 junction I to be welded, realize the follow-up technique that forms silver-colored intermediate layer 13 in the junction I chemical plating to be welded of aluminium target 11.

In step S123, the object of described pickling processes is the oxide-film of removing for the first time on the junction I to be welded of aluminium target 11, and the junction I to be welded to aluminium target 11 further activates, increase the follow-up speed that zinc is processed of soaking, make the follow-up zinc-impregnating layer even compact forming at the junction I to be welded of aluminium target 11.Remove and can not remove completely the junction to be welded of aluminium target 11 for the first time, so pickling processes can only partly be removed the junction to be welded of aluminium target 11.In the present embodiment, pickling processes agent is the mixture of hydrofluoric acid, nitric acid and water, hydrofluoric acid: nitric acid: the volume ratio of water is (1:3:4) ~ (3:5:4).The described pickling processes time is 30s ~ 40s.If the pickling processes time is less than 30s, the effect of activation completely is not played in pickling processes agent; If the pickling processes time is greater than 40s, the junction I to be welded of pickling processes agent meeting corrosion aluminium target 11.

In step S124, the junction I to be welded of the aluminium target 11 after described pickling processes is cleaned.Detailed process is that object is for the acid solution of the junction I to be welded of aluminium target 11 is cleaned up with pure water or deionized water rinsing aluminium target 11 1min ~ 2min, prevents from remaining in the zincate solution of the acid solution contaminate subsequent of aluminium target 11.

In step S125, after the junction I to be welded of the aluminium target 11 of overpickling immerses zinc liquid in the state of activation, ejected electron, the electromotive force of the junction I to be welded of aluminium target 11 is negative moving further, make the junction I to be welded of aluminium target 11 there is higher electro-chemical activity, the alchlor oxide-film that makes to be present on the junction I to be welded of aluminium target 11 dissolves, and, once have aluminium to come out on the junction I to be welded of aluminium target 11, by the zinc ion in zinc liquid, replaced immediately, the zinc crystal grain of height of formation disperse, the highly dispersed color of one deck being comprised of zinc crystal grain is caesious rete, be zinc layer, above-mentioned displacement reaction can stop gradually when forming the zinc layer of one deck densification, , the junction I to be welded of aluminium target 11 will be covered completely by zinc layer as thin as a wafer, original oxide-film on the junction I to be welded of aluminium target 11 is removed for the second time, described removal for the second time as removing completely, the activity of the junction I to be welded of aluminium target 11 is further strengthened, can make follow-up chemical plating process to form the better effects if in silver-colored intermediate layer 13.

Add complexing agent, can make displacement reaction slowly and evenly carry out, can on the junction I to be welded of aluminium target 11, deposit good, tiny, the fine and close and uniform zinc layer of one deck adhesion.In the present embodiment, also in zinc dipping solution, add a small amount of molysite and nickel salt, be specially with sodium potassium tartrate tetrahydrate and will after molysite and nickel salt complexing, add in zinc dipping solution, make iron ion, nickel ion and zinc ion codeposition, to improve the adhesion of zinc and metalwork matrix, and improve corrosion resistance.

In soaking the process of zinc, there are important impact number of times, the composition of zinc dipping solution, the temperature of zinc dipping solution and the immersion plating time of soaking zinc processing on zinc layer.In the present embodiment, carry out soaking for twice zinc and process, soak zinc number of processes very little, the oxide-film on the junction I to be welded of aluminium target 11 can not be removed completely, affects the quality of follow-up formation zinc layer; Soak zinc number of processes too many, cause the waste of technique.Soak for the first time the composed as follows of zinc dipping solution that zinc processes: zinc sulfate (ZnSO47H ₂o) 75g/L ~ 85g/L; NaOH (NaOH) 130g/L ~ 150g/L; Sodium potassium tartrate tetrahydrate (KNaC ₄h ₄o ₆4H ₂o) 40g/L ~ 60g/L; Ferric trichloride (FeCl ₃) 1g/L ~ 3g/L.The temperature of soaking zinc processing is room temperature.The temperature of soaking zinc processing is greater than room temperature, easily causes the distortion of the junction I to be welded of aluminium target 11; The temperature of soaking zinc processing is less than room temperature, and the junction I to be welded of aluminium target 11 is difficult for being cemented out by zinc.In the present embodiment, the time of soaking zinc processing is 30s ~ 60s.Galvanizing time is greater than 60s, can cause the waste of soaking the zinc processing time; Galvanizing time is less than 30s, can cause that to soak zinc reaction insufficient, and the junction I to be welded of aluminium target 11 can not form complete continuous zinc layer.Soak for the first time the zinc layer rough porous that zinc process to form, adhere to badly, also have a small amount of oxide-film to exist, therefore, also need to soak for the second time zinc and process, in the present embodiment, the described zinc that soaks is for the second time processed with to soak for the first time zinc processing identical.In other embodiments, soak for the second time zinc and process and can process differently from soaking for the first time zinc, for example the concentration of zinc dipping solution be not equal.As long as it is just passable to make the junction I to be welded of aluminium target 11 form even, careful zinc layer.

Afterwards, the described junction I to be welded that soaks the aluminium target 11 of zinc processing can be cleaned.Detailed process is that object is for the zincate solution on the junction I to be welded surface of aluminium target 11 is cleaned up with pure water or deionized water rinsing metalwork surface 1min ~ 2min.

The following describes the chemical plating treatment step of the present embodiment.

Chemical plating is a kind of energising that do not need, and according to principle of oxidation and reduction, utilizes strong reductant in containing the solution of metal ion, metal ion is reduced into metal and is deposited on the method that various material surfaces form coating.In the present embodiment, chemical silvering is under the catalytic action of argent, produces the deposition process of argent by controllable redox reaction in the solution that contains argent ion.Please refer to Fig. 4, utilize method silver-plated intermediate layer 13 in junction to be welded of chemical plating.

Concrete technology is: the aluminium target 11 soaking after zinc is processed is immersed in the chemical plating fluid 41 of 40 li of electroless plating tanks, described chemical plating fluid 41 comprises silver salt solution and reductant solution, less stable due to chemical plating fluid 41, therefore silver salt solution and reductant solution need to be configured respectively, mix and use again before silver-plated.In the present embodiment, the composition of described silver salt solution comprises: main salt silver nitrate (AgNO3) 55g/L ~ 65g/L, additive NaOH (NaOH) 40g/L ~ 45g/L and complexing agent ammoniacal liquor (NH ₃4H ₂o) 40g/L ~ 50g/L.The main component of described reductant solution comprises: glucose (C ₆h ₁₂o ₆) 40g/L ~ 30g/L, tartaric acid (C ₄h ₆o ₆) 3g/L ~ 6g/L and ethanol (C ₂h ₅oH) 90g/L～110g/L.The volume ratio of described silver salt solution and reductant solution is 1:1.

The key reaction occurring in above-mentioned chemical plating fluid is:

[Ag (NH3) 2] OH+H (reducing agent) → Ag ↓+2NH3+H2O

Please continue to refer to Fig. 5, the quality that adopts the silver-colored intermediate layer 13 that the method for chemical silvering forms on the junction I to be welded of aluminium target 11 is closely related with the welding effect of follow-up aluminium target 11 and copper backboard 12.Color and luster is even and bright, does not have the purity in silver-colored intermediate layer 13 of yellow or black color spot higher, makes more silver diffuse in aluminium target 11 and copper backboard 12 in welding process, increases weld strength; Tiny and the fine and close silver-colored intermediate layer 13 of particle is more conducive to silver and diffuses to aluminium target 11 and copper backboard 12, has shortened diffusion time, has improved the welding efficiency of aluminium target 11 and copper backboard 12 and increase weld strength.Therefore,, for forming the high silver-colored intermediate layer 13 of quality, inventor has studied Electroless Silver Plating and has formed the major influence factors in silver-colored intermediate layer 13 and be provided with the preferably process conditions of chemical silvering, specific as follows:

In chemical plating fluid 41, silver nitrate concentration is too high, in the time of can causing some free silver ion to be present in chemical plating fluid, and the stability decreases of chemical plating fluid 41, the silver-colored intermediate layer 13 obtaining is usually a bit darkish in color, and color and luster is inhomogeneous; The concentration of silver nitrate is too low, silver-colored intermediate layer 13 densification not that the plating speed (deposition velocity of chemical plating fluid) of chemical plating fluid 41 declines and forms.Complexing agent ammoniacal liquor forms silver-colored amine complex ion solution in chemical plating fluid 41, and the concentration of ammoniacal liquor is higher, and chemical plating fluid 41 is more stable, but the too high plating speed that also can affect.Additive is speed regulator, and the concentration of concentration additive is higher, and deposition velocity can be faster, but excessive concentration can make chemical plating fluid 41 decompose.The standard electrode potential of silver is 0.8V, is easy to be reduced.The concentration of reducing agent is larger, and the deposition velocity of silver rises, but the concentration of reducing agent is also restricted, otherwise easily causes the coat of metal coarse, even brings out the instantaneous decomposition of chemical plating fluid.Composition and the proportioning of the reducing agent in the chemical plating fluid 41 of employing the present embodiment, the deposition velocity of guarantee chemical plating fluid 41 existing maximums, has again good stability.

In the present embodiment, the major influence factors that Electroless Silver Plating forms silver-colored intermediate layer 13 also comprises the temperature of chemical plating fluid 41, useful load and the plating time of the pH value of chemical plating fluid 41, chemical plating fluid 41.

The deposition velocity of chemical plating fluid 41 raises and speeds with temperature, but it is pointed out that chemical plating fluid 41 excess Temperatures, and plating speed declines on the contrary, and plating solution surface has silver to separate out.In the present embodiment, preferred temperature is 15 ℃ ~ 20 ℃.Rising temperature contributes to the quickening of chemical reaction, and silver mirror reaction is the endothermic reaction, rising bath temperature, and molecular motion speed is accelerated, collision frequency showed increased, reaction rate is accelerated thereupon.But excess Temperature is unfavorable for the deposition of silver atoms, cause silver to be separated out in a large number and enter plating solution, and excess Temperature can causes silver-colored intermediate layer 13 in uneven thickness, short texture, rough surface.On the contrary, if temperature is on the low side, although the deposited particles of silver is tiny, 13 densifications of silver-colored intermediate layer, reaction is slow, and production efficiency is low, and easily occurs yellow or black color spot.In addition, in chemical silvering process, temperature is controlled evenly very importantly, preferably maintains the temperature change of solution in ± 2 ℃, if temperature fluctuation is excessive in plating process, can produce sheet silver intermediate layer 13, affects the adhesion in silver-colored intermediate layer 13.

The pH value of chemical plating fluid 41 has larger impact to the formation in the deposition velocity of chemical plating fluid and silver-colored intermediate layer 13.Chemical silvering is a process that consumes OH-, with pH value, rises, and has enough OH-in plating solution, and silver-colored deposition velocity is accelerated, but affects the stability of chemical plating fluid simultaneously.PH value changes also can affect the stress distribution in silver-colored intermediate layer 13, and the silver-colored intermediate layer 13 that the plating solution that pH value is high obtains shows as tension, otherwise the silver-colored intermediate layer 13 that the plating solution that pH value is low obtains shows as compression.In the present embodiment, pH scope is 9.0 ~ 12.0, and the silver-colored intermediate layer 13 of formation there is no stress,, can form the silver-colored intermediate layer 13 of even compact that is, can make the adhesion of silver-colored intermediate layer 13 and aluminium target better.Need in process of production to maintain the pH value of chemical plating fluid 41, within making be controlled at ± 0.2 scope of its fluctuation range.Can adopt dilute sodium hydroxide or sodium potassium tartrate tetrahydrate to adjust the pH value of chemical plating fluid.

The useful load of chemical plating fluid (the plating solution amount of loading in coating bath) is at 0.5dm ²/ L ~ 1.5dm ²/ L.Useful load is excessive, and catalytic surface is excessive, and deposition reaction is violent, affects the stability of chemical plating fluid and the performance in silver-colored intermediate layer 13; Useful load is too small, and in chemical plating fluid, small impurity particle just can become catalytic active center and cause deposition, easily causes chemical plating fluid to decompose.

In the present embodiment, the plating duration of chemical plating can be 60min ~ 80min, and now silver-colored intermediate layer 13 is the best in quality, gained silver intermediate layer 13 lights, cellular structure even compact.The junction I to be welded of aluminium target 11 the thickness in silver-plated intermediate layer 13 be 10 μ m ~ 15 μ m.

In the present embodiment, in chemical plating step, silver-colored intermediate layer 13 is formed on each surface upper (please refer to Fig. 4) of aluminium target 11, by the method for machining, (please refer to Fig. 5) is removed in other the silver-colored intermediate layers 13 except junction I to be welded.

In other embodiment, also can only be formed on the silver-colored intermediate layer 13 of the upper formation of junction I to be welded of aluminium target 11.Treat solder side I other surfaces in addition and protect, make other surfaces not carry out above-mentioned sequence of operations, just cost is higher than the cost of a upper embodiment.

In the present embodiment, after above-mentioned chemical silvering forms silver-colored intermediate layer 13, described aluminium target 11 is taken out from electroless plating tank 40, after other the silver-colored intermediate layers 13 except junction I to be welded being removed by the method for machining, adopt hyperacoustic method to clean being formed with the aluminium target 11 in described silver-colored intermediate layer 13, be used for removing pollutant, can greatly improve the cleanliness factor in the upper silver-colored intermediate layer 13 forming of junction I to be welded of aluminium target 11, make the welding effect in follow-up welding procedure better.In order to prevent that aluminium target from getting rusty, described cleaning agent is isopropyl alcohol or alcohol.After cleaning, to being formed with the aluminium target 11 in described intermediate layer 13, carry out vacuum drying, be specially at 70 ℃ ~ 100 ℃ and be incubated 1 hour ~ 2 hours, the liquid of aluminium target 11 inside is volatilized totally under the condition of vacuum, realize finish-drying.

Please continue to refer to Fig. 3 and Fig. 5, there are two junctions to be welded in silver-colored intermediate layer 13, i.e. the first junction I ' to be welded and the second junction II ' to be welded.The first junction I ' to be welded is the surface that need weld with the junction I to be welded of aluminium target 11, and the second junction II ' to be welded is the surface that need weld with the junction II to be welded of copper backboard 12.

The junction II to be welded of described copper backboard 12 is the bottom of copper backboard groove 121, is equally also the surface that will weld with the second junction II ' to be welded in silver-colored intermediate layer 13.

Then, the machining processes such as the junction II to be welded to copper backboard 12 polishes, turnning and milling, on the one hand for removing oxide layer, grease and the dust of the junction II to be welded of copper backboard 12, make on the other hand the junction II to be welded of copper backboard 12 have certain surface roughness, described surface roughness is that Ra is greater than 2.5mm.Can make like this junction II to be welded of copper backboard 12 and silver-colored intermediate layer 13 close contact more,, the junction II to be welded of copper backboard 12 and the distance in silver-colored intermediate layer 13 are enough near, between copper atom and silver atoms, produce gravitational force between atoms, thereby make copper atom and silver atoms more easily carry out phase counterdiffusion,, in diffusion process, can reduce the welding pressure between aluminium target 11 and copper backboard 12 and reduce welding temperature, aluminium target 11 and copper backboard 12 are more easily welded, improving welding efficiency.

Then adopt hyperacoustic method to clean copper backboard, for removing pollutant, can greatly improve the cleanliness factor of the junction II to be welded of copper backboard 12, make the welding effect in follow-up welding procedure better.In order to prevent that copper backboard 12 from getting rusty, described cleaning agent is isopropyl alcohol or alcohol.After cleaning, to being formed with described copper backboard 12, carry out vacuum drying, be specially at 70 ℃ ~ 100 ℃ and be incubated 1 hour ~ 2 hours, the liquid of copper backboard 12 inside is volatilized totally under the condition of vacuum, realize finish-drying.

Then, please refer to Fig. 5 and Fig. 6, execution step S13, is placed in vacuum canning by the aluminium target 11, the copper backboard 12 that are formed with described silver-colored intermediate layer 13 and makes described silver-colored intermediate layer 13 between described aluminium target 11 and copper backboard 12, and described vacuum canning 14 is placed in welding equipment.

Be specially, the aluminium target 11 that is formed with silver-colored intermediate layer 13 be placed on to the groove of copper backboard 12, and silver-colored intermediate layer 13 forms assembly to be welded, the groove side of the side IV laminating copper backboard 12 of aluminium target 11 between aluminium target 11 and copper backboard 12.Between the first junction I ' to be welded in the junction I to be welded of aluminium target 11 and silver-colored intermediate layer 13, form place to be welded between the second junction II ' to be welded in silver-colored intermediate layer 13 and the solder side II of copper backboard 12.

Then this assembly to be welded is placed in vacuum canning 14.Acting as of vacuum canning 14 prevents that assembly to be welded is oxidized the in the situation that of heating.It should be noted that, the material of vacuum canning 14 is selected to need to meet two conditions, and first condition is: the fusing point of vacuum canning 14 is higher than the temperature in follow-up heating process, otherwise vacuum canning 14 can melt in follow-up heating process; Second condition is: in the welding process of follow-up aluminium target 11 and copper backboard 12, the material of vacuum canning can realize preferably pressure conduction, otherwise affect the welding quality of follow-up aluminium target 11 and copper backboard 12, for example aluminium target 11 is good not with the solder bond power of copper backboard 12, and weld strength is not good etc.In the present embodiment, preferably use aluminium sheet welding fabrication, for example, the trade mark is 1060 pure aluminum plates, 1070 pure aluminum plates, 1035 pure aluminum plates and 1050 pure aluminum plates, can better meet above-mentioned two conditions.In other embodiments, be not limited to aluminium sheet, as long as meet the material of above-mentioned two conditions, can be used as vacuum canning.The thickness of vacuum canning 14 is 2.5mm ~ 3.0mm.If vacuum canning 14 is too thin, in the welding process of follow-up aluminium target 11 and copper backboard 12, the weld of vacuum canning 14 easily splits, the phenomenon that causes assembly to be welded to expose and leak gas; If vacuum canning 14 is too thick, in the welding process of follow-up aluminium target 11 and copper backboard 12, vacuum canning 14 is not easy to realize pressure conduction.

Vacuum canning 14 can be by Machine Design, CAD for example, make its shape meet the shape of assembly to be welded, afterwards by seamless tubular goods or sheet material through splicing formation welded together, therefore, vacuum canning 14 can fit tightly built-in target material assembly to be welded and not be subject to the size restrictions of assembly to be welded, can realize the welding of large-size target.As shown in Figure 6, on this vacuum canning 14, generally leave a hole 15, can be for drawing deaeration pipe from described jacket 14, this deaeration pipe is connected with vaccum-pumping equipment.

The aluminium target 11, the copper backboard 12 that are formed with described silver-colored intermediate layer 13 are placed in after vacuum canning 14, and sealed vacuum jacket 14 also stays deaeration pipe.The technique of sealing can realize by argon arc welding, vacuumizes step and completes by deaeration pipe.

The detailed process vacuumizing is as follows: first vacuum canning 14 being evacuated to vacuum is 2 * 10 ^-3pa, then puts into heating furnace by vacuum canning 14 and heats, and temperature is 250 ℃ ~ 350 ℃, then starts limit heating edge and vacuumizes, and then carries out incubation step, is incubated 3 hours ~ 4 hours.The inventor finds, treats target material assembly and carries out preheating, is conducive to improve on the one hand the welding efficiency of follow-up welding procedure, carries out on the other hand follow-up holding one's breath during technique under the condition of heating and thermal insulation, and deaeration pipe can deliquescing, more easily the afterbody of deaeration pipe is shut.The inventor also finds, when the temperature of vacuum canning external environment condition is 250 ℃ ~ 350 ℃, the volatile matter escape target material assembly of inside in target material assembly, vacuum in vacuum canning is increased on the contrary, so in described heating and insulating process, need to continue to vacuumize to vacuum canning 14, make the vacuum in vacuum canning 14 again reach 2 * 10 ^-3pa.Vacuum in this embodiment in vacuum canning 14 is 2 * 10 ^-3pa, is not limited to this value in the present invention, vacuum in vacuum canning 14 meets and is less than or equal to 2 * 10 ^-3pa.

In above-mentioned heating and thermal insulation process, if the temperature of heating is too low, component to be welded is heated and is insufficiently unfavorable for follow-up welding operation nor is beneficial to the carrying out vacuumizing; The excess Temperature of heating, the crystal grain of component to be welded is easily grown up, and crystallite dimension can surpass scope.The internal temperature that is incubated 2 hours ~ can realizes whole assembly to be welded for 5 hours reaches design temperature uniformly, if temperature retention time is too short, component internal temperature to be welded can not thermally equivalent, and vacuum does not reach requirement; If temperature retention time is long, the crystal grain of assembly to be welded is easily grown up, and crystallite dimension can surpass scope.If the vacuum in vacuum canning 14 is greater than 2 * 10 ^-3pa, the assembly to be welded in jacket can be oxidized in follow-up calendering technology; Vacuum in vacuum canning is the smaller the better.

To vacuum canning 14 insulations, after 2 hours ~ 5 hours, continuation keeps the state of vacuum canning 14 inner vacuum to its technique of holding one's breath, and is about to deaeration pipe sealing, makes an airtight vacuum environment of the inner formation of vacuum canning.The described technique of holding one's breath is to realize by machining and welding, in the present embodiment, can the afterbody of vacuum canning deaeration pipe be pounded and flatly then with argon arc welding, be sealed with iron hammer.Hold one's breath after technique, the vacuum of described vacuum canning is at least 2 * 10 ^-3pa.

After vacuum canning 14 is held one's breath, vacuum canning 14 is placed in welding equipment to carry out welding procedure, described welding equipment is high temperature insostatic pressing (HIP) stove.

Then,, please continue to refer to Fig. 6, execution step S14, utilizes heat and other static pressuring processes that described aluminium target 11 and the copper backboard 12 that is formed with silver-colored intermediate layer welded together to form target material assembly.

High temperature insostatic pressing (HIP) (hotisostatic pressing, HIP) be that assembly to be welded is placed in vacuum-packed vacuum canning 14, then under hot conditions, utilize highly pressurised liquid or gases at high pressure to apply each to impartial pressure to vacuum canning 14, make vacuum canning in this high temperature and high pressure environment, keep a period of time so that material to be welded is closely welded together.

In the present embodiment, the aluminium target 11 that is formed with silver-colored intermediate layer with the principle that copper backboard 12 carries out high temperature insostatic pressing (HIP) welding is:

Because vacuum canning 14 is by very thin thickness, having the preferably aluminium sheet welding of pressure conduction forms, externally under the effect of environmental stress, vacuum canning 14 can be realized good pressure conduction and make between the junction I to be welded of aluminium target 11 and the first junction I ' to be welded in silver-colored intermediate layer 13, mineralization pressure between the second junction II ' to be welded in silver intermediate layer 13 and the junction II to be welded of copper backboard 12, simultaneously because vacuum canning 14 is arranged in hot environment for a long time, between the first junction I ' to be welded in the solder side I of aluminium target 11 and silver-colored intermediate layer 13, can generation plastic deformation between the silver second junction II ' to be welded in intermediate layer 13 and the junction II to be welded of copper backboard 12 and high-temerature creep and the aluminium target 11 of realizing small size contacts with the crystal grain between silver-colored intermediate layer 13, copper backboard 12 contacts with the crystal grain between silver-colored intermediate layer 13, under continuous effect, crystal grain contact area expands gradually, finally reach place to be welded and can realize crystal grain contact, make between aluminium atom and silver atoms, between copper atom and silver atoms, form gravitational force between atoms.

Between aluminium atom and silver atoms, form after gravitational force between atoms between copper atom and silver atoms, the phase counterdiffusion between aluminium atom and silver atoms occur at place to be welded, between copper atom and silver atoms, at this moment be diffused as small size diffusion.Along with the lasting diffusion of aluminium atom, silver atoms and the copper atom at place to be welded and cause the various crystal defects such as distortion of lattice, dislocation, room, thereby caused each junction to be welded surface at place to be welded to enlarge markedly, further caused aluminium atom, silver atoms and copper atom in height state of activation, make the diffusive migration of aluminium atom, silver atoms and copper atom very rapid, the large area that is diffused as at this moment spreads.Large area diffuses to aluminium-silver metal key and the copper-silver metal key that forms Large-Area-Uniform, just reaches poised state, and now, large area diffusion stops, and welding process stops.Form aluminium-silver metal key of Large-Area-Uniform and the process of copper-silver metal key as follows, first the tiny area at place to be welded forms with aluminium-silver metal key and copper-silver metal key, then take aluminium-silver metal key of these tiny areas and the joint that copper-silver metal key is main type of attachment, in whole each junction to be welded, form aluminium-silver metal key and copper-silver metal key of Large-Area-Uniform, large area diffusion process finishes, thereby welding process finishes.

By selecting suitable technological parameter can make aluminium target 11 in the target material assembly after welding there is higher combination rate, weld strength with copper backboard 12, concrete, inventor finds to adopt following technological parameter to realize: ambient temperature is 300 ℃ ~ 350 ℃, utilize highly pressurised liquid or gases at high pressure to make external environment condition pressure be more than or equal to 90Mpa, be incubated 2 hours ~ 4 hours.Under these process conditions, can make the left space of assembly waiting disappear completely, make place to be welded all form metallic bond, realize the homogenising of metallic bond, increase solder bond rate and the weld strength of assembly to be welded.Ambient temperature of the present invention is that welding temperature welding temperature relative and prior art is lower, make the inner crystal grain of aluminium target 11 in target material assembly be not easy recrystallization occurs and grow up, the crystallite dimension that is the aluminium target 11 in target material assembly is less than 100 μ m, most of grain orientation is crystal orientation (200), make the internal organizational structure of aluminium target 11 meet sputter requirement, but also there is good sputter effect.

Be specially, if ambient temperature lower than 300 ℃, can not activate between the junction I to be welded of aluminium target 11 and the first junction I ' to be welded in silver-colored intermediate layer 13, the diffusion of the second junction II ' to be welded in silver-colored intermediate layer 13 and the atom between the junction II to be welded of copper backboard 12.If ambient temperature is higher than 350 ℃, the crystal grain of aluminium target 11 is easily grown up on the one hand, and the crystal orientation of aluminium target 11 easily changes; On the other hand, easily cause the waste of cost; In addition, if appearance environment temperature continues to raise, be greater than the fusing point of copper backboard 12 or aluminium target 11, easily make aluminium target 11 and 12 fusings of copper backboard.If external environment condition pressure lower than 90Mpa, can not activate between the junction I to be welded of aluminium target 11 and the first junction I ' to be welded in silver-colored intermediate layer 13 equally, the diffusion of the second junction II ' to be welded in silver-colored intermediate layer 13 and the atom between the junction II to be welded of copper backboard 12; External environment condition pressure is more high better, the restriction of just receiving at present process equipment.If temperature retention time is less than 2 hours, can not make the more uniform diffusion of the metallic bond of assembly to be welded, if temperature retention time 4 hours causes the waste of insulation cost.

In the present embodiment, with silver-colored intermediate layer 13, there is following effect:

Aluminium target in jacket 14 11 and copper backboard 12 are carried out in the process of high temperature insostatic pressing (HIP) welding, aluminium target 11 and copper backboard 12 thickness are large, more difficult distortion, and only have the silver-colored intermediate layer 13 of 0 μ m ~ 15 μ m to be easily out of shape, in welding process, utilize silver-colored plastic deformation and Plastic Flow, make the concentration gradient of diffusing atom at place to be welded larger, more easily promote aluminium atom, phase counterdiffusion between copper atom and silver atoms, accelerate the disappearance in diffusion space, place to be welded, can make aluminium target 11 and copper backboard 12 in welding process, there is shorter weld interval, improve welding efficiency.

When aluminium target 11 and copper backboard 12 weld, due to the sudden change of aluminium target 11 and copper backboard 12 physical and chemical performances, particularly because aluminium target 11 is different with the thermal coefficient of expansion of copper backboard 12, place to be welded easily produces very large thermal stress.Choose silver as intermediate layer 13, the diffusion activation energy of silver is lower, than other materials, more easily diffuse in aluminium target 11, more easily diffuse in copper backboard 12 simultaneously, be that place to be welded more easily forms gradient joint, can better avoid or reduce the thermal stress at place to be welded, thereby thereby avoid place to be welded to cause that distortion improves the weld strength at place to be welded.

When aluminium target 11 and copper backboard 12 weld, beyond form generation Solder for Al-Cu Joint Welding (AlCu) compound divided by metallic bond, carbon in copper and reactive aluminum also form aluminium carbide (AlC), and aluminium carbide belongs to fragility phase, easily make the place to be welded fracture of aluminium target 11 and copper backboard 12.Adopt silver to do intermediate layer 13 while carrying out high temperature insostatic pressing (HIP) welding, can suppress the appearance of aluminium carbide fragility phase, can also avoid or reduce place to be welded and form harmful eutectic impurity, to increase welding rate and the increase weld strength between aluminium target 11 and copper backboard 12.

In addition, due to vacuum canning 14, be not subject to the restrictions such as aluminium target 11 sizes and copper backboard 12 sizes, the vacuum canning 14 that large scale assembly to be welded is housed can be put into high temperature insostatic pressing (HIP) stove, adopt the welding procedure of high temperature insostatic pressing (HIP) under high temperature, condition of high voltage, vacuum canning 14 to be applied respectively and realizes uniform large-area welding to equalization pressure, form large-sized target material assembly.The weld welding rate of described large-sized target material assembly is high, weld strength is large and not yielding etc.

Then, the step S15 in please execution graph 1, after having welded, carries out coolingly to described vacuum canning, remove described vacuum canning to obtain described target material assembly.

After having welded, can make vacuum canning 14 cooling in air, be cooled to below 200 ℃, then by chemical method or mechanical means, remove vacuum canning 14 to obtain target material assembly, for example, can utilize turning process that vacuum canning 14 is removed, and then pass through the methods such as turning or line cutting, thereby make the target material assembly of final size.

Embodiment bis-

Embodiment bis-is that the method in the silver-colored intermediate layer 13 of silver-plated formation is for electroplating on the junction I to be welded of described aluminium target 11 with the difference of embodiment mono-.

Plating is the process of utilizing electrolysis principle silver-colored intermediate layer of silver-plated formation in the junction to be welded of aluminium target.During plating, silver metal is done anode, is oxidized to cation and enters electroplate liquid; The junction to be welded of aluminium target is done negative electrode, and the cation of silvering is reduced formation silvering in the junction to be welded of aluminium target.For getting rid of other cationic interference, and make silvering evenly, firmly, need cook electroplate liquid with the solution of silver ion, to keep the concentration of the silver ion in silvering constant.

Please refer to Fig. 7, in the present embodiment, silver metal 71 is connected on to anode 72, the junction I to be welded of aluminium target 11 is connected on to negative electrode 73.Anode and cathode is connected with the electrolyte solution that contains silver ion.Electroplating bath 74 passes to after galvanic power supply 75, and the silver metal 71 of anode can be oxidized, and loses electronics, silver ion in solution is in cathodic reduction, obtain electronics and form atom and accumulate in negative electrode top layer, that is, silver forms silver-colored intermediate layer 13 ' in the junction I to be welded of aluminium target 11 deposition.

Electroplate liquid comprises: silver chlorate (AgCl) 33g/L ~ 39g/L, potassium cyanide (KCN) 40g/L ~ 70g/L, potash (K ₂cO ₃) 10g/L ~ 15g/L.

The quality that adopts the silver-colored intermediate layer 13 ' that the method for electrosilvering forms on the junction I to be welded of aluminium target 11 is closely related with the welding effect of follow-up aluminium target 11 and copper backboard 12.The purity in the silver-colored intermediate layer 13 ' that color and luster is even and bright is higher, makes more silver diffuse in aluminium target 11 and copper backboard 12 in welding process, increases weld strength; Tiny and the fine and close silver-colored intermediate layer 13 ' of particle is more conducive to silver and diffuses to aluminium target 11 and copper backboard 12, has shortened diffusion time, has improved the welding efficiency of aluminium target 11 and copper backboard 12 and increase weld strength.Therefore,, for forming the high silver-colored intermediate layer 13 ' of quality, inventor has studied electrosilvering technique and has formed the major influence factors in silver-colored intermediate layer 13 ' and be provided with the preferably process conditions of electrosilvering, specific as follows:

In electroplate liquid, main component is silver chlorate, so the concentration of silver chlorate is larger on the impact of electroplating.The excessive concentration of silver chlorate, in the time of can causing some free silver ion to be present in electroplate liquid, the stability decreases of electroplate liquid, the silver-colored intermediate layer 13 ' obtaining is usually a bit darkish in color, and color and luster is inhomogeneous; The concentration of silver chlorate is too low, silver-colored the intermediate layer 13 ' [densification not that electroplating velocity declines and forms.

Potassium cyanide is complexing agent, and in electroplate liquid, the concentration of potassium cyanide is higher, and electroplate liquid is more stable, but but too highly also can affect electroplating velocity.

Potash is speed regulator in electroplate liquid, and the concentration of potash is higher, and deposition velocity can be faster, but excessive concentration can make chemical plating fluid decompose.Composition in the electroplate liquid of employing the present embodiment, guarantee is electroplated the electroplating velocity of existing maximum, has again good stability.

In the present embodiment, the major influence factors that adopts electrosilvering technique to form silver-colored intermediate layer 13 ' also comprises temperature, power supply and the plating time of cathode-current density, electroplate liquid.

Any plating solution has a cathode-current density scope that obtains good coating, and the minimum electrical current density that obtains good coating claims cathode-current density lower limit, and the maximum current density that obtains good coating claims the cathode-current density upper limit.In the present embodiment, described cathode-current density is 0.25A/dm ²~ 0.5A/dm ², when cathode-current density is too low, cathodic polarization effect is little, and the crystallization crystal grain in silver-colored intermediate layer 13 ' is thicker, and along with the increase of cathode-current density, the polarization of negative electrode also increases thereupon, and it is careful tight that the 13 ' crystallization of silver-colored intermediate layer also becomes thereupon; But the current density on negative electrode can not be excessive, can not surpass the higher limit allowing, otherwise, due near famine silver ion negative electrode, on the junction I to be welded of whole aluminium target 11, produce shape and produce shape as the loose silver-colored intermediate layer 13 ' of sponge as the silver-colored intermediate layer 13 ' of branch or on the junction I to be welded of whole aluminium target 11.

In the present embodiment, the temperature of described electroplate liquid is 15 ℃ ~ 20 ℃, and the silver-colored intermediate layer 13 ' crystallization that obtains is like this tiny and can accelerate deposition velocity, enhances productivity.Can improve in addition electric conductivity, promotion anodic solution, raising cathode efficiency, the coating internal stress etc. that reduces of solution.If the temperature of electroplate liquid is too high, accelerate cathode reaction speed and ion diffusion velocity, reduce cathodic polarization effect, can make 13 ' the crystallization chap of silver-colored intermediate layer.If the temperature of electroplate liquid is too low, silver cannot be electroplated on the junction I to be welded of aluminium target 11.

According to the difference of the number of phases of AC power and rectification circuit, can obtain various current waveform.Such as single-phase half-wave, single-phase full wave, three-phase semiwave and three-phase full-wave etc.Facts have proved, the waveform of electric current is all influential to the aspects such as consumption of the dispersibility of the crystalline structure of coating, brightness, plating solution and covering power, alloying component, additive.In the present embodiment, adopting transistor switch power is the pulse power.This power supply has that volume is little, efficiency is high, superior performance, ripple factor are stable. and be not subject to the features such as output current impact, and silver-colored intermediate layer 13 ' the crystalline structure exquisiteness and the brightness that at the junction I to be welded of aluminium target 11, form are high.In other embodiment, also can adopt direct current, also can obtain that crystalline structure is tiny, the good silver-colored intermediate layer 13 ' of brightness.

In addition, in electroplating process, had better not stir electroplate liquid, if electroplate liquid is stirred, must carry out regular or continuous filtration operation, to remove various solid impurities and the dregs in electroplate liquid, otherwise can reduce the adhesion in silver-colored intermediate layer 13 ' and the silver-colored intermediate layer 13 ' that forms is coarse, loose, porous on the junction I to be welded of aluminium target 11.To the stirring of electroplate liquid, can accelerate the convection current of electroplate liquid, near the silver ion that has made to consume negative electrode is supplemented in time, reduce the concentration polarization effect of negative electrode, thereby in the situation that other condition is identical, stirring can make coating particle become large, crystallization chap.

Finally, the welding situation of the target material assembly in above-described embodiment one and embodiment bis-is detected:

Utilize C-SCAN(Water Immersion Ultrasonic C-scan system) detect solder bond rate, its solder bond rate scope of target material assembly that should be comprised of aluminium target and copper backboard is more than 95%.Adopt stretching experiment machine to test its hot strength, can reach 100MPa left and right.The test of employing perpendicularity, the flexural deformation of target material assembly is very little.Adopt crystal orientation microscope test, in target material assembly, the grain size of aluminium target is controlled at below 100 μ m, and most of grain orientation of aluminium target is crystal orientation (200),, the internal organizational structure of aluminium target can meet the requirement of semiconductor target sputter, even in sputter procedure, can produce good sputter effect.The target material assembly aluminium target material assembly serviceability temperature that method forms thus can reach more than 600 ℃, and the phenomenon that target material assembly can not come off under such hot conditions also can be carried out normal sputtering technology.Result shows, adopts the welding performance of the aluminium target material assembly that in the present invention, welding method obtains very reliable.

Aluminium target in the present invention is not limited to the highly purified aluminium target of describing in above embodiment, can be also aluminium alloy target.The material of copper backboard can be fine copper, can be also copper alloy, and for example the trade mark is the copper alloy of C18000 and C18200.

Although the present invention with preferred embodiment openly as above; but it is not for limiting the present invention; any those skilled in the art without departing from the spirit and scope of the present invention; can utilize method and the technology contents of above-mentioned announcement to make possible change and modification to technical solution of the present invention; therefore; every content that does not depart from technical solution of the present invention; any simple modification, equivalent variations and the modification above embodiment done according to technical spirit of the present invention, all belong to the protection domain of technical solution of the present invention.

Claims

1. a welding method for target material assembly, is characterized in that, comprises the following steps:

Aluminium target and copper backboard are provided;

2. method according to claim 1, is characterized in that, in the junction to be welded of described aluminium target, silver-plated method is chemical plating or plating.

3. method according to claim 2, is characterized in that, the chemical plating fluid that described chemical plating adopts comprises silver salt solution and reductant solution, and described silver salt solution comprises silver nitrate 55g/L ~ 65g/L, NaOH 40g/L ~ 45g/L and ammoniacal liquor 40g/L ~ 50g/L; Described reductant solution comprises glucose (C ₆h ₁₂o ₆) 40g/L ~ 30g/L, tartaric acid (C ₄h ₆o ₆) 3g/L ~ 6g/L and ethanol (C ₂h ₅oH) 90g/L～110g/L, the volume ratio of described silver salt solution and reductant solution is 1:1, and the temperature of chemical plating fluid is 15 ℃ ~ 20 ℃, and the pH value of chemical plating fluid is 9.0 ~ 12.0, and the plating time of described chemical plating is 60min ~ 80min.

4. method according to claim 2, is characterized in that, the electroplate liquid that described plating adopts comprises silver chlorate (AgCl) 33g/L ~ 39g/L, potassium cyanide (KCN) 40g/L ~ 70g/L and potash (K ₂cO ₃) 10g/L ~ 15g/L, the temperature of described electroplate liquid is 15 ℃ ~ 20 ℃, described cathode-current density is 0.25A/dm ²~ 0.5A/dm ², the plating time of described plating is 50min ~ 70min.

5. method according to claim 1, is characterized in that, the thickness in described silver-colored intermediate layer is 10 μ m ~ 15 μ m.

6. method according to claim 1, is characterized in that, the described heat and other static pressuring processes that utilizes comprises being formed with the aluminium target in silver-colored intermediate layer and step that copper backboard welds together:

7. method according to claim 6, is characterized in that, the welding of aluminum that described vacuum canning is is 2.5mm ~ 3.0mm by thickness forms, and after described aluminium target and copper backboard are placed in vacuum canning, is evacuated to 2 * 10 to vacuum canning described in major general ^-3pa, then by described vacuum canning sealing.

8. method according to claim 7, is characterized in that, the process that described vacuum canning vacuumizes is the process that limit heating edge vacuumizes, and the temperature of described heating is 250 ℃ ~ 350 ℃.

9. method according to claim 1, is characterized in that, in described junction to be welded, before the step in the silver-colored intermediate layer of silver-plated formation, described junction to be welded is carried out to pretreatment, and described pretreatment comprises the following steps:

10. method according to claim 1, is characterized in that, after forming the step in silver-colored intermediate layer, by being formed with the aluminium target in described silver-colored intermediate layer and copper backboard, being placed in and also comprising step before the step in vacuum canning in the junction to be welded of described aluminium target: