CN102328157A - Method for manufacturing SnAgCu lead-free solder - Google Patents
Method for manufacturing SnAgCu lead-free solder Download PDFInfo
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- CN102328157A CN102328157A CN201110267897A CN201110267897A CN102328157A CN 102328157 A CN102328157 A CN 102328157A CN 201110267897 A CN201110267897 A CN 201110267897A CN 201110267897 A CN201110267897 A CN 201110267897A CN 102328157 A CN102328157 A CN 102328157A
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Abstract
The invention discloses a method for manufacturing SnAgCu lead-free solder, which comprises the following steps of: mixing raw materials according to proportions, heating to 500 DEG C under the protection of a covering agent and nitrogen gas or under the vacuum condition, smelting for 0.5-1h to obtain alloy melt; heating the alloy melt to a temperature not lower than a temperature range that the alloy melt generates liquid-state structure transformation, and preserving heat for 15-30min; cooling to 500 DEG C, preserving heat for 0.5h, and then casting and solidifying to obtain a lead-free solder alloy ingot; and finally machining the alloy ingot into lead-free solder by adopting a transmission machining way. According to the lead-free solder prepared by adopting the method disclosed by the invention, solidification tissues are remarkably thinned and evenly distributed; in the welding process, a reaction layer at the joint part is remarkably thinned and the roughness is reduced; the solder is easy to melt, and the expandability of the solder and the wettability of the solder with a copper substrate are remarkably improved; besides, the thermal stability of welding joint tissues is remarkably improved, and therefore the operation reliability of related products in the service process is improved.
Description
One, technical field
The present invention relates to a kind of preparation method of lead-free solder, specifically a kind of SnAgCu is the preparation method of ternary alloy leadless scolder.
Two, background technology
Tin-lead (Sn-Pb) brazing metal (welding rod, welding wire, soldering paste etc.) is because each item superior performance; Its processing performance reaches with low cost well in addition; Be used widely in various countries, like various electronics (computer, display, colour TV, mobile phone etc.), electrical equipment and instrument product, microelectronics Packaging always; The assembling of printed circuit board (pcb) comprises plug-in mounting (THT) and mounted on surface (SMT).Yet because the leaded electronic waste of nuisance that waits has significant damage to the mankind, lead poisoning can be brought out diseases such as leukaemia, ephrosis, heart disease, insanity, therefore, and the plumbous common recognition that has become the whole mankind of forbidding.The WEEE of European Union and RoHS instruction 6 kinds of harmful substances such as (in electric, the electronic product) forbidding Pb is in formal enforcement on July 1st, 2006.China Ministry of Information Industry has also passed through the related management method, and regulation was listed in the electronics and IT products that electronics and IT products pollute the keypoint control catalogue from July 1st, 2006 can not leadedly wait nuisance.From 1998, Japanese HITACHI, PANASONIC, SONY, TOSHIBA, electronics corporations such as FUJITSU actively carry out unleaded, and product reaches unleaded respectively wholly or in part at present.Though the U.S. does not carry out not having lead welding through making laws, because of receiving day, Europe competitive pressure, each major company of the U.S. is also in the solution of actively seeking not have lead welding." unleaded " of scolder become a kind of inexorable trend.
In recent years, doing big quantity research and adjustment aspect lead-free solder material itself and related process and the equipment both at home and abroad.Lead-free solder is the basis usually with Sn; Add Ag, Cu, Bi, Zn, In grade in an imperial examination 2 metallic element component alloys, and add the 3 4th kind of unit through trace and usually adjust its mechanical property (intensity, toughness, fatigue resistance etc.), physical and chemical performance (electric conductivity, thermal conductivity, non-oxidizability, corrosion resistance etc.) and processing performance (wetability, flowability, fusing point, fusion temperature scope etc.).According to serviceability temperature, lead-free solder mainly can be divided three classes: high temperature Sn-Ag (Cu) is; In warm Sn-Zn system; Low temperature Sn-Bi system.
Sn-Ag-Cu is that scolder is on the basis of Sn-Ag scolder, to add Cu to form owing to have that fusing point is low, wetability is higher relatively and advantage such as high comprehensive performance, be acknowledged as present combination property best, use the widest leadless welding alloy.The current Sn-Ag-Cu system that uses mainly contains the Sn3.0Ag0.5Cu that Japan thousand lives and U.S. Aiwa state university is held, and (addition of Ag is 3% of the raw material gross mass in the alloy compositions, and the addition of Cu is 0.5% of a raw material gross mass, and surplus is Sn; Hereinafter the statement of alloy compositions is analogized in this way) and Sn3.8Ag0.7Cu patented product and the quaternary alloy scolder Sn-Ag-Cu-Sb that on its basis, develops, Sn-Ag-Cu-Bi (USP4879096 and CAP1299471), Sn-Ag-Cu-Ni (USP4758407) and NCMS recommend the Sn-Ag-Cu-Zn that uses.Near eutectic point (at present definite eutectic point is still fuzzy, and nearly eutectic area can only be provided, and its fusion temperature is 217-221 ℃), its fusing point is just low more, and its melting region (being Mushy Zone) is also narrow more more for Sn-Ag-Cu ternary eutectic alloy, composition.Though add the fusing point that low melting point constituent element (Bi, In etc.) can reduce alloy, its melting region will increase, the butt welded seam reliability is unfavorable.Though can improve otherwise performance and add other constituent elements, but increase the difficulty that the melting preparation is produced.Moreover the mechanical property of Sn-Ag-Cu scolder is original just superior than Sn-Pb scolder, and needing working as of concern is the wetability and assembling temperature window (reduce fusing point, or reduce the melting region width the to reduce the backflow peak temperature) problem of scolder.
The Sn-Ag-Cu scolder is sprawled wetting the playing a leading role of reaction in the process on copper coin; When solder fusing begins; The LIQUID Sn atom spreads rapidly along substrate surface; And take the lead in sprawling the forward position at molten drop with Cu reaction bonded on the substrate and form skim reactant film (IMC), be referred to as pioneer's film (precursor film) on the document, the scolder molten drop is actually on pioneer's film and sprawls; And the Cu atom of sprawling substrate in the process spreads in the scolder molten drop through the reaction thin layer, and the Sn-Cu class in the molten drop is rolled into a ball admittedly bunch and to be adhered to thin layer that to promote that the conversion zone forming core increases big simultaneously.Like this, in the molten drop melt structure butt welded seam conversion zone growing state influence significantly, the group's bunch size in the scolder molten drop of conventional smelting preparation method is bigger, especially the Sn-Cu class is rolled into a ball admittedly and bunch is helped intermetallic compound Cu to substrate attachment
6Sn
5Forming core is grown up, and the reactant growth interface seems coarse, promotes conversion zone to thicken more; Viscosity is bigger greatly because of group's bunch size in the molten drop simultaneously, is unfavorable on coarse reactant interface, flowing sprawling.In a word, the scolder of conventional method preparation spreading wetting performance on the one hand remains further to be improved, and its weld seam conversion zone is thick partially on the other hand, and also coarse relatively with the interface of scolder, tissue defects is easy to generate, and the butt welded seam reliability is unfavorable.
In a word, the processing performance of reliability, welding or the presswork of scolder and formation joint thereof, the crucial category of genus lead-free solder.And the solidified structure of lead-free solder and joint thereof is determining dependability parameters such as intensity, toughness, fatigue resistance, in the welding process scolder to the sprawling of base-material, wetability also is one of key factor of scolder operation technique performance.
To above-mentioned subject matter, data at home and abroad shows, optimization and trace element (like rare earth) that the research of lead-free solder is mainly concentrated on into component selections, proportioning are on all kinds of Effect on Performance.Few people pay close attention to the preparation condition of unleaded brazing metal itself, such as the thermal history condition that influences the metal bath structure and properties.And in manufacture of materials and scientific research reality, people notice that for a long time often there are liquid-solid heredity in structure and aspect of performance.
Three, summary of the invention
The present invention aims to provide a kind of method of the SnAgCu of preparation lead-free solder, with obtain being prone to fusing, sprawl fast, to the copper base wetability is good, mechanical performance is good, the lead-free solder of joint microstructure good stability.
Technical solution problem of the present invention adopts following technical scheme:
The characteristics that the present invention prepares the method for SnAgCu lead-free solder are to operate according to the following steps:
Each raw material is pressed proportional quantity to be mixed; Under coverture protection, nitrogen protection or vacuum condition, be warming up to and obtained alloy melt in 500 ℃ of melting 0.5-1 hours; Alloy melt is warming up to the temperature that is not less than said alloy melt generation Liquid Structure transformation is incubated 15-30 minute, be cooled to 500 ℃ of insulations 0.5 hour then; Casting solidification obtains the leadless welding alloy ingot subsequently; Mode through conventional mechanical processing is processed into lead-free solder with said alloy pig at last.
The characteristics that the present invention prepares the method for SnAgCu lead-free solder also are: the said temperature that is not less than said alloy melt generation Liquid Structure transformation is 1050-1100 ℃.
Said each raw material constitutes by mass percentage: Ag3.0-4.0%, and Cu0.5-1.0%, surplus is Sn.The control of solder compositions proportioning and trace impurity is decided by manufacturer's product requirement during concrete the preparation.
Said proportional quantity is the amount that takes by weighing after the ratio metering in the formation of each raw material and qualification.
Said coverture is conventional covertures such as boric acid or borax.
The mode of said machining is the mode of pressure rolling, wire drawing or the processing of other conventional mechanicals.
Said scolder is processed into the scolder of forms such as paper tinsel, sheet, rod, silk or powdery according to the machining mode of routine.
Scientific basis of the present invention and technical foundation:
In recent years; Inventor and other researchers show with multiple means research; Some bianry alloy melt temperature-rise periods can occurrence temperature induce discontinuous liquid-liquid structure to change; Comprising the ANOMALOUS VARIATIONS of the responsive physical quantity of structures such as viscosity, thermal capacitance, resistance, in-fighting, and the diffraction result of some alloy melts shows, structural parameters generation flip-flop (F.Q.Zu et al such as atomicity NC in its atomic distance r1, ligancy N1, degree of order ξ, group bunch; PHYSICAL REVIEW LETTERS 89,125505 (2002); U.Dahlborg et al, Journal of Non-Crystalline Solids 353 (2007) 3005-3010; F.Q Zu et al; New physical phenomena:temperature-induced liquid-liquid transition in alloys and its effects upon solidification, Symposium on Extraction and Processing Division held at the TMS 2009 Annual Meeting and Exhibition, FEB 15-19; 2009 San Francisco CA; EPD CONGRESS 2009, PROCEEDINGS, 525-533).Through research to SnAgCu series lead-free solder melt property; The inventor finds to change (Liu Yongchi, Zu Fangdao etc., China Science & Technology University's journal in 1050 ℃ of following different temperatures interval (trace with composition changes) melt generation Liquid Structure; 2011 06 phase 535-539,555).Also find simultaneously; With under the low relatively temperature not the SnAgCu melt that changes of recurring structure compare; Liquid Structure takes place down and changes the remarkable refinement of solidified structure of SnAgCu melt afterwards in high temperature; And the scolder that so prepares not only welds the spreading wetting processing performance of process obviously to be improved, and welding back joint microstructure and reliability also obviously are improved.
The present invention is in view of the production difficulty of multicomponent alloy melting preparation; Just only select Sn-Ag-Cu three constituent elements; The raw material constituent is nearly eutectic composition Sn-Ag (3.0-4.0wt%)-Cu (0.5-1.0wt%); Purpose be obtain faster burn-off rate (result of the remarkable refinement of scolder crystal grain) in the welding process thus be easy to sprawl, avoid other elements to bring harmful effect for the solder performance aspect, also simplify the smelting operation process simultaneously.
Can know by achievement in research; At low-temperature region relatively (like Sn 3.5Ag0.7Cu alloy 400-600 ℃ of temperature range) and high-temperature area (like Sn 3.5Ag0.7Cu alloy 850-1050 ℃ of temperature range) the Liquid Structure transformation takes place for the SnAgCu ternary alloy three-partalloy temperature-rise period of nearly eutectic composition respectively more than liquidus curve; Wherein the transformation of low-temperature region (400-600 ℃) has invertibity relatively; Not obvious to the solidified structure influence, and the transformation of high-temperature area (850 ℃-1050 ℃) is irreversible, remarkable to solidified structure; Conventional smelting temperature is all far below 800 ℃, i.e. temperature before the melt structure irreversible transformation.
These scientific basis of the present invention just and technical foundation place.
For illustrating novel smelting technology action effect in the present invention, select the conventional melting scope of 500 ℃ of 1h among the embodiment respectively for use, and 500 ℃ of 0.5h+850 ℃ of 15 minutes two kinds of preparation technologies, compare with the result of preparation method's of the present invention smelting technology.
Compared with present technology, beneficial effect of the present invention is embodied in:
1, the SnAgCu lead-free solder that obtains of preparation method of the present invention is through the hyperthermia and superheating melting; The remarkable effect that melt structure changes is the remarkable refinement of solidified structure of scolder itself and is evenly distributed; And the tissue of mother metal can obtain more intact heredity through the temperature short time thermal history of nearly fusing point, and welding line joint is organized remarkable refinement.
2, only need the conventional constituent element of Sn, Ag and Cu among the preparation method of the present invention, need not add other constituent elements, reduce cost.
3, the SnAgCu lead-free solder that obtains of preparation method of the present invention; Because the result of the remarkable refinement of scolder crystal grain; In the welding process, obtaining faster, thereby the burn-off rate scolder is easy to sprawl; The peak temperature of Reflow Soldering also can suitably reduce like this, and reduces the possibility that peak temperature will reduce substrate damage.Simultaneously, narrow melting region helps the quick cooled and solidified of weld seam, reduces the probability of rosin joint.
4, the SnAgCu lead-free solder that obtains of preparation method of the present invention; Can form pioneer's film of fine and close relative smooth; And the melt viscosity that forms is less, and the wetability of scolder and base material is strong in the welding process, and the conversion zone attenuate of intersection; The joint shear strength obviously improves (5-12%), and Joint Reliability is improved.
5, preparation method of the present invention is simple to operation, helps popularizing, and has versatility.As long as guarantee that the highest smelting temperature is more than 1050 ℃ and be incubated and just be enough to reach the melting effect more than 15 minutes.
6, the heat aging test shows that the welding point heat endurance that the inventive method prepares scolder also obviously is improved, and this tissue, stability to product joint in the practical application is significant.
Four, description of drawings
Fig. 1 is the micrograph after the lead-free solder of different temperatures preparation is poured into a mould, and wherein scheming a is the lead-free solder of embodiment 1 preparation, and figure b is the lead-free solder of embodiment 2 preparations, and figure c is the lead-free solder that embodiment 3 prepares.As can be seen from Figure 1; Figure a is cooled to the scolder that 500 ℃ of melting 30min prepare by the scolder and the figure b of conventional temperature (500 ℃ of melting 60min) preparation at 850 ℃ of melting 15min subsequently; Nascent β-Sn phase that considerable amount is not only arranged in the solidified structure, and the intermetallic compound in the eutectic structure is rendered as very long needle-like; And the scolder of (1050 ℃ of melting 10min are cooled to 500 ℃ of melting 30min subsequently) melting preparation under the high temperature of figure c after melt structure changes; Nascent β-Sn mutually seldom in the solidified structure; The overwhelming majority is an eutectic, and the intermetallic compound in the eutectic structure is refined as hour hand shape even granular.
Fig. 2 is that the lead-free solder of the embodiment of the invention 3 preparation is sprawled photo on copper base.Wherein scheming b is the black and white design sketch that obtains with behind the photoshop processing figure a.Result according to such method obtains on computers with Photoshop and image-pro software processes, finally obtains spreading area and assembly average thereof (the spreading area data among Fig. 4).
Fig. 3 is the side view of lead-free solder on copper base of different temperatures preparation.Among Fig. 3 from left to right preparation temperature be respectively 500 ℃, 850 ℃ and 1050 ℃ (being the scolder of embodiment 1, embodiment 2 and embodiment 3 preparations).According to the side view picture result,, finally obtain angle of wetting and assembly average thereof (the angle of wetting data among Fig. 4) on computers with Photoshop and image-pro software processes.The angle of wetting that also can intuitively find out 1050 ℃ of melting preparation scolders in Fig. 3 side view obviously reduces.
Fig. 4 is statistical average result's the comparison of spreading area and angle of wetting of lead-free solder Reflow Soldering on copper coin of different temperatures preparation.Wherein scheme 240 ℃ of peak temperatures, the time 60s of the Reflow Soldering of a, 240 ℃ of peak temperatures, the time 120s of the Reflow Soldering of figure b.As can be seen from Figure 4; Handle the scolder for preparing after (embodiment 3) according to the inventive method; Spreading area under two kinds of reflow soldering process conditions (wetting area) obviously increases, angle of wetting (wetting angle) obviously reduces, and shows that the welding process performance for preparing scolder by the inventive method is able to obvious raising.
Fig. 5 is the stressed sketch map of scolder melt wettability equilibrium on copper base of the embodiment of the invention 3 preparations.This figure can help to understand from mechanism, and the roughness of intermetallic compound reactant film (IMC) and pioneer's film thereof (precursor film) is to sprawling the influence of characteristic and angle of wetting on scolder and the substrate interface.
Fig. 6 is seam organization and the micrograph (240 ℃ of the peak temperatures of Reflow Soldering on the copper base, time 120s) of conversion zone of the lead-free solder of different temperatures preparation.Wherein scheming a is the scolder of embodiment 1 preparation, and figure b is the scolder of embodiment 2 preparations, and figure c is the scolder of embodiment 3 preparations.As can be seen from the figure obviously attenuate and roughness reduction of the scolder welding back joint intersection intermetallic compounds layer (nitride layer, white layer) of embodiment 3 (the inventive method) preparation.
Fig. 7 is that the scolder (a) of conventional preparation condition (embodiment 1) preparation and the scolder (b) of the inventive method (embodiment 3) preparation weld the port pattern contrast after joint is broken with copper base, and the contrast of relevant shear intensity data (breaking portion occurs on the solder matrix).It is thus clear that the fracture of figure a is the compound characteristics of " cleavage+dimple ", the dimple characteristic (plasticity and toughness that reflection excellent) of the fracture of figure b for elongating, shear strength also obviously improves thereupon.
Fig. 8 is the heat stabilization test contrast of the scolder (a) of conventional preparation condition (embodiment 1) preparation and the scolder (b) that the inventive method (embodiment 3) prepares.Wherein scheming a is the situation of the scolder welding joint of conventional preparation condition (embodiment 1) preparation at 150 ℃ of timeliness 240h; Figure b is that the welding joint of scolder of the inventive method (embodiment 3) preparation is in the situation of 150 ℃ of timeliness 240h; Figure c is the Ageing Treatment of carrying out 0h, 120h, 240h and 480h under 150 ℃ of air atmosphere respectively, the variation tendency of intermetallic compound reactant film (IMC) thickness.It is thus clear that the thickness of the intermetallic compound reactant film (IMC) of the scolder (b) of the inventive method (embodiment 3) preparation and copper base welding joint increases slower in ag(e)ing process, and the size of the intermetallic compound of scolder inner (photo top) is much also little.
Five, the specific embodiment
Preparation method of the present invention is very simple; Prepare the not oxidized pollution of process as long as can guarantee alloy; And the insulation of the temperature (more than 1050 ℃) after melt structure changes appropriate time (is confirmed according to weight alloy and firing equipment; Generally within 30 minutes), other conditions are identical with conventional preparation technology.
Embodiment 1 and embodiment 2 are the contrast experiment of embodiment 3, are not the scopes that the present invention protects.
Embodiment 1:
SnAgCu is that the raw material of ternary alloy leadless scolder constitutes by mass percentage in the present embodiment:
Ag3.5％，Cu0.7％，Sn95.8％。
Present embodiment SnAgCu is that the ternary alloy leadless scolder is to prepare according to the following steps:
Each raw material mixed to be incorporated in being warming up to 500 ℃ of meltings under the nitrogen protection and obtaining alloy melt in 1 hour by proportional quantity, guarantee that alloy melting mixes, pour into alloy pig subsequently; Mode through machining is processed into scolder with said alloy pig at last.The form processing of scolder can be the mode of pressure rolling, wire drawing or the processing of other conventional mechanicals according to actual requirement, thereby obtains the scolder that form is paper tinsel, sheet, rod, silk, grain or powdery.Scolder is laminar in this example.
Embodiment 2:
SnAgCu is that the raw material of ternary alloy leadless scolder constitutes by mass percentage in the present embodiment:
Ag3.5％，Cu0.7％，Sn95.8％。
Present embodiment SnAgCu is that the ternary alloy leadless scolder is to prepare according to the following steps:
Each raw material mixed to be incorporated in being warming up to 500 ℃ of meltings under the nitrogen protection and obtaining alloy melt half an hour by proportional quantity, then said alloy melt is warming up to 850 ℃ of insulations 15 minutes; Be cooled to 500 ℃ of insulations 0.5 hour again, pour into alloy pig subsequently; Mode through machining is processed into scolder with said alloy pig at last.The form processing of scolder can be the mode of pressure rolling, wire drawing or the processing of other conventional mechanicals according to actual requirement, thereby obtains the scolder that form is paper tinsel, sheet, rod, silk, grain or powdery.Scolder is laminar in this example.
Embodiment 3:
SnAgCu is that the raw material of ternary alloy leadless scolder constitutes by mass percentage in the present embodiment:
Ag3.5％，Cu0.7％，Sn95.8％。
Present embodiment SnAgCu is that the ternary alloy leadless scolder is to prepare according to the following steps:
Each raw material mixed to be incorporated in being warming up to 500 ℃ of meltings under the nitrogen protection and obtaining alloy melt half an hour by proportional quantity, then said alloy melt is warming up to 1050 ℃ of insulations 15 minutes; Be cooled to 500 ℃ of insulations 0.5 hour again, pour into alloy pig subsequently; Mode through machining is processed into scolder with said alloy pig at last.The form processing of scolder can be the mode of pressure rolling, wire drawing or the processing of other conventional mechanicals according to actual requirement, thereby obtains the scolder that form is paper tinsel, sheet, rod, silk, grain or powdery.Scolder is laminar in this example.
The present invention sees (a) and (b), (c) among Fig. 1 to the action effect of scolder solidified structure: embodiment 1, embodiment 2, embodiment 3 different preparation method's gained scolder solidified structures; It is thus clear that; The solidified structure of embodiment 1, embodiment 2 does not have obvious difference; And the solidified structure of embodiment 3 significantly improves, and has reflected that the Melt Overheating Treatment that scolder prepares process must could obtain effect to improving the scolder tissue in the temperature after melt structure changes.
Embodiment 4:
Scolder with embodiment 1 preparation welds on copper base, and the reflow soldering technological parameter is respectively 240 ℃ of brazing temperatures, 60 seconds time, and 240 ℃ of brazing temperatures, 120 seconds time, and brazing flux selects for use Q/IEPZ02-91 type solder(ing) paste as brazing flux.The main scolder of investigating is sprawled effect and wetability, and experiment is carried out according to standard GB/T 11364-2008 " solder wetting property experimental technique ".
Embodiment 5:
Scolder with embodiment 2 preparation welds on copper base, and the reflow soldering technological parameter is respectively 240 ℃ of brazing temperatures, 60 seconds time, and 240 ℃ of brazing temperatures, 120 seconds time, and brazing flux selects for use Q/IEPZ02-91 type solder(ing) paste as brazing flux.The main scolder of investigating is sprawled effect and wetability, and laboratory reference standard GB/T 11364-2008 " solder wetting property experimental technique " is carried out.
Embodiment 6:
Scolder with embodiment 3 preparation welds on copper base, and the reflow soldering technological parameter is respectively 240 ℃ of brazing temperatures, 60 seconds time, and 240 ℃ of brazing temperatures, 120 seconds time, and brazing flux selects for use Q/IEPZ02-91 type solder(ing) paste as brazing flux.The main scolder of investigating is sprawled effect and wetability, and the experiment rules are carried out with reference to standard GB/T 11364-2008 " solder wetting property experimental technique ".
The present invention is to the action effect of scolder processing performance:
The spreading area of scolder and angle of wetting result see Fig. 4 a (240 ℃, 60 seconds) and Fig. 4 b (240 ℃, 120 seconds) after embodiment 4, embodiment 5, embodiment 6 solderings, and each data is obtained (seeing the illustrative method of Fig. 2 and Fig. 3) in the histogram by the statistical average as a result of 6 samples.As can be seen from Figure 4; Scolder according to the acquisition of the inventive method Processing of Preparation; Spreading area under two kinds of reflow soldering process conditions (wetting area) obviously increases, angle of wetting (wetting angle) obviously reduces, and shows that the welding process performance for preparing scolder by the inventive method is able to obvious raising.
The present invention welds the action effect of back joint intersection intermetallic compounds layer (IMC) to scolder: thickness and the roughness of the welding joint IMC (nitride layer, white layer) of the scolder of embodiment 4, embodiment 5, embodiment 6 (240 ℃, 120 seconds time on the copper base), see (a) and (b), (c) among Fig. 6 respectively.Visible by Fig. 6, obvious attenuate of the scolder welding back joint intersection intermetallic compounds layer (nitride layer, white layer) of the present invention's preparation and roughness reduce (Fig. 6 (c)).
Embodiment 7:
Scolder with embodiment 1 preparation carries out shearing test after welding on the copper base:
The simple shear lap joint form of experiment employing standard is done 3 experiments and is averaged.Brazing process parameter: 240 ℃ of brazing temperatures, 60 seconds time, the soldering slit is controlled between the 0.08-0.1mm.After soldering finishes, take out air cooling.Shearing experiment carries out on the CMT5105 electronic universal tester, and rate of extension is 2mm/min.
Embodiment 8:
Scolder with embodiment 3 preparations is carrying out shearing test after the welding on the copper base, and method is with embodiment 7.
The improvement effect of Joint Reliability: Fig. 7 was that the scolder (a) of conventional preparation condition (embodiment 7) preparation and the scolder (b) of the inventive method (embodiment 8) preparation contrast with the port pattern that copper base welds after joint is broken after the present invention welded scolder, and the contrast of relevant shear intensity data.It is thus clear that the present invention is to the scolder welding back Joint Reliability effect of having clear improvement.
Embodiment 9:
After welding on the copper base, carry out the heat stabilization test of joint with the scolder of embodiment 1 preparation:
The solder joint reflow brazing process parameter is 240 ℃ of brazing temperatures, 120 seconds time.Heat stabilization test adopts the heat aging method; The Ageing Treatment of 0h, 120h, 240h and 480h is carried out in test respectively under 150 ℃ of air atmosphere; Investigate the variation tendency of intermetallic compound reactant film (IMC) thickness, and the change in size of intermetallic compound contrasts in the scolder.
Embodiment 10:
After welding on the copper base, carry out the heat stabilization test of joint with the scolder of embodiment 3 preparations:
The solder joint reflow brazing process parameter is 240 ℃ of brazing temperatures, 120 seconds time.Heat stabilization test adopts the heat aging method; The Ageing Treatment of 0h, 120h, 240h and 480h is carried out in test respectively under 150 ℃ of air atmosphere; Investigate the variation tendency of intermetallic compound reactant film (IMC) thickness, and the change in size of intermetallic compound contrasts in the scolder.
The present invention welds the improvement effect of back joint heat endurance to scolder: heat aging test portion result sees (a) and (b), (c) of Fig. 8.Visible by Fig. 8; Compare with conventional preparation method (embodiment 9); The thickness that the inventive method prepares the intermetallic compound reactant film (IMC) of scolder and copper base welding joint increases obviously slow down (embodiment 10) in ag(e)ing process, and the size of the intermetallic compound of scolder inner (photo top) is much also little.As everyone knows, printed circuit board or electronic product unavoidably can produce heat and the temperature rising in running, and the heat endurance of solder joints tissue directly has influence on the operating reliability of product.Undoubtedly, the inventive method is to prepared scolder product joint microstructure, performance stable significant in practical application.
Claims (2)
1. method for preparing the SnAgCu lead-free solder is characterized in that operating according to the following steps:
Each raw material is pressed proportional quantity to be mixed; Under coverture protection, nitrogen protection or vacuum condition, be warming up to and obtained alloy melt in 500 ℃ of melting 0.5-1 hours; Alloy melt is warming up to the temperature that is not less than said alloy melt generation Liquid Structure transformation is incubated 15-30 minute; Be cooled to 500 ℃ of insulations 0.5 hour then, casting solidification obtains the leadless welding alloy ingot subsequently, and the mode through machining is processed into lead-free solder with said alloy pig at last.
2. preparation method according to claim 1 is characterized in that: the said temperature that is not less than said alloy melt generation Liquid Structure transformation is 1050-1100 ℃.
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| CN103273217A (en) * | 2013-05-29 | 2013-09-04 | 哈尔滨工业大学深圳研究生院 | Partially-reinforced high-reliability brazing filler metal and preparing method thereof |
| US9198302B2 (en) | 2012-07-18 | 2015-11-24 | Koninklijke Philips N.V. | Method of soldering an electronic component with a high lateral accuracy |
| CN109518019A (en) * | 2018-10-12 | 2019-03-26 | 北京康普锡威科技有限公司 | A kind of method of modified SnBi system hypoeutectic alloy and obtained alloy |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9198302B2 (en) | 2012-07-18 | 2015-11-24 | Koninklijke Philips N.V. | Method of soldering an electronic component with a high lateral accuracy |
| CN103273217A (en) * | 2013-05-29 | 2013-09-04 | 哈尔滨工业大学深圳研究生院 | Partially-reinforced high-reliability brazing filler metal and preparing method thereof |
| CN103273217B (en) * | 2013-05-29 | 2016-01-13 | 哈尔滨工业大学深圳研究生院 | High reliability solder of a kind of local strengthening and preparation method thereof |
| CN109518019A (en) * | 2018-10-12 | 2019-03-26 | 北京康普锡威科技有限公司 | A kind of method of modified SnBi system hypoeutectic alloy and obtained alloy |
| CN109518019B (en) * | 2018-10-12 | 2020-06-19 | 北京康普锡威科技有限公司 | Method for modifying SnBi series hypoeutectic alloy and alloy obtained by method |
| CN112157257A (en) * | 2020-09-17 | 2021-01-01 | 中国科学院电工研究所 | In-situ toughening method for tough and integral Cu/Sn/Ag welding material |
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