CN102500946A - Sn-Ag-Cu-Bi-Er low-silver and lead-free welding flux and preparation method for same - Google Patents
Sn-Ag-Cu-Bi-Er low-silver and lead-free welding flux and preparation method for same Download PDFInfo
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- CN102500946A CN102500946A CN2011103180924A CN201110318092A CN102500946A CN 102500946 A CN102500946 A CN 102500946A CN 2011103180924 A CN2011103180924 A CN 2011103180924A CN 201110318092 A CN201110318092 A CN 201110318092A CN 102500946 A CN102500946 A CN 102500946A
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Abstract
The invention relates to a Sn-based low-silver and lead-free welding flux containing a rare earth element Er as well as a preparation method for the same. The Sn-based low-silver and lead-free welding flux comprises the following components in percentage by mass: 0.3-2.0% of Ag, 0.3-0.7% of Cu, 2.0-3.0% of Bi, 0.01-0.15% of Er and the remaining of Sn, wherein Bi can reduce a melting point of a welding flux alloy but increase a melting range of the same; and Er can reduce the melting range. During the preparation of the welding flux, an intermediate alloy Sn-10Er is smelted under a vacuum state or in an atmosphere of protective gases, and the intermediate alloy is prepared into a lead-free welding flux alloy ingot according to the proportion of the alloy. The ingot can be directly regarded as the welding flux, and can also be prepared into a bar, a wire, a plate or powder for use; the welding flux has the advantages of low melting point (201-220 DEG C), small range of melting range, good wetting property, excellent mechanical property and technical performances as well as low cost.
Description
Technical field
The present invention relates to a kind of low-silver lead-free solder that contains rare earth erbium and preparation method thereof, belong to the manufacturing technology field of tin-base lead-free solder.
Background technology
Along with the development of electronic industry green manufacturing and the progress of electronics package technique, traditional Sn-Pb scolder is replaced by the lead-free solder of nonhazardous gradually.A kind of novel Lead-free Electronics Packaging scolder should have characteristics such as processing performance good (fusing point is low, the fusion temperature scope is little, wetability good, anticorrosive antioxygenic property is good, good conductivity), welding spot reliability good (bond strength is high, creep-resistant property good), cost are low.Up to now, the lead-free solder kind of having developed is a lot, is that Sn-3.5wt%Ag, Sn-0.7wt%Cu and SnAgCu are alloy by several kinds of lead-free solders that generally use, but also has some problems.Current large usage quantity, combination property are better, what receive that scientific research personnel and manufacturer pay close attention to is that SnAgCu is a scolder, can be applicable to the various forms of scolder; But its fusing point (about 217 ℃) is high to the requirement of materials to be welded and welding equipment far above the plumbous eutectic solder of traditional tin.Miniaturization development along with electronic devices and components; The electronics assembling will be adopted advanced surface mount process (SMT) more and more, and the Reflow Soldering of development technology is because process window is narrower thereupon, and packaging density is high; The thermal shock resistance of electronic devices and components is limited, requires to use more low-melting scolder.Therefore; In the quaternary solder alloy that is developed out by SnAgCu system Sn-Ag-Cu-Bi being arranged is alloy, Sn-(3.5 ~ 7.7) Ag-(1 ~ 4) Cu-(0 ~ 10) Bi that announces like USP5527628 and Sn-(3.5 ~ 4.5) Ag-(0 ~ 5) Cu-(0 ~ 9.3) Bi of USP5520752 announcement.These scolders have improved SnAgCu ternary scolder to a certain extent, but also have deficiency in some aspects, and bigger than normal like the fusion range (193 ℃ ~ 218 ℃) of the former alloy, the fatigue resistance of latter's alloy is on the low side.Find that through the retrieval of prior art document Lu Bin etc. (China YouSe Acta Metallurgica Sinica, the 17th the 4th phase of volume, 518-524,2007) mention the fusion range that in the SnAgCu scolder an amount of Er of interpolation can effectively reduce solder alloy, the crystal grain of refinement alloy; And US2009014746 has announced quaternary alloys such as Sn-3.5Ag-0.5Cu-1.0Er, proposes to add the wetability that rare earth element can improve scolder.
It is that the scolder cost is higher relatively that higher silver content makes SnAgCu; Particularly descending along with the rising of silver-colored valency and electronic product price in recent years; Its marketing resistance strengthens; Low-silver lead-free solder just becomes the emphasis of research and development, in the hope of guaranteeing to reduce the cost of scolder under the scolder serviceability prerequisite.First batch of low-silver lead-free solder Sn-0.3Ag-0.7Cu (SAC0307) was developed out and introduced to the market in 2007.Hundred million cities, Shenzhen reach to be discovered, add wetability that Bi can improve SAC0307 and reduce the scolder fusing point, but melting range can increase, and the postwelding mechanical property is had a negative impact.Sn-0.1Ag-3.0Cu-1.0Bi in the low easy-flo that USP4879096 early announces, its fusing point is 217 ℃, melting range is wide to reach 17 ℃.According to present technical process, the fusing point of scolder is preferably under 215 ℃, and melting range is less than 15 ℃.Therefore, the better low silver-colored low-melting point leadless scolder of lower, performance of R&D costs and the applied environment coupling inevitable requirement that is Electronic Packaging.
Summary of the invention
The purpose of this invention is to provide a kind of low silver, low melting point, little melting range, wetability is good, and mechanical performance and processing performance are better, service-strong Sn-Ag-Cu-Bi-Er low-silver lead-free solder and preparation method thereof.
For realizing the foregoing invention purpose, the present invention takes following technical scheme:
A kind of Sn-Ag-Cu-Bi-Er low-silver lead-free solder of the present invention is characterized in that it being that following each component and percentage by weight: Ag are arranged is 0.3-2.0%, and Cu is 0.3-0.7%, and Bi is 2.0-3.0%, and Er is 0.01-0.15%, and surplus is Sn; The purity of each component raw material is respectively: Bi >=99.99%, Er >=99.9%, Ag >=99.99%, Cu >=99.99%, Sn >=99.99%.
A kind of Sn-Ag-Cu-Bi-Er low-silver lead-free solder of the present invention is characterized in that the preferred composition of this scolder and content (percentage meter by weight) are: Ag is 1.0-2.0%, and Cu is 0.3-0.5%, and Bi is 2.0-3.0%, and Er is 0.05-0.10%, and surplus is Sn.
The preparation method of a kind of Sn-Ag-Cu-Bi-Er low-silver lead-free solder of the present invention is characterized in that comprising following process and step:
1. under vacuum state or protective gas atmosphere, adopt existing method of smelting and equipment to prepare intermediate alloy Sn-(10 ~ 12) Er;
2. chemical analysis is confirmed the actual content of Er among the intermediate alloy Sn-Er of refining; In vaccum sensitive stove, be converted into the weight of Sn-Er intermediate alloy and pure Cu, Ag, Bi, Sn then, and be prepared into Sn-Ag-Cu-Bi-Er solder alloy ingot blank by the composition of scolder of the present invention and weight proportion;
3. the above-mentioned alloy ingot blank that obtains is encapsulated in the quartz ampoule, at 300 ℃ of following remeltings, casting ingot-forming.Can also make the product of various ways such as welding rod, welding wire, weld tabs, soldered ball, welding powder, soldering paste, can be used for each welding link of Electronic Packaging or assembling.
The present invention through reducing Ag content, adds bismuth additions and Er and has obtained a kind of quinary alloy scolder Sn-Ag-Cu-Bi-Er on the basis of nearly eutectic SnAgCu alloy.
Silver content reduces, and the scolder fusing point can raise.Research shows, add Bi and can effectively remedy because of Ag content reduces the fusing point that causes and rise, and improve the wetability of scolder, but the fusion temperature scope of scolder can increase, and the mechanical property of postwelding solder joint is had a negative impact.And add the fusion temperature scope that rare earth element er can dwindle alloy, and especially make the fusion temperature scope increase problem that behind introducing Bi, causes be able to control, help improving the combination property of scolder.Add the mutual supplement with each other's advantages that has realized each element interaction in the time of Bi and Er.
Bismuth additions preferably is controlled at below 3.0% in the scolder of the present invention, and being higher than this value alloy melting temperature range will increase; And the solder embrittlement raising because the inclined to one side coazevation of Bi is sent as an envoy to, the comprehensive serviceability of deterioration scolder.The content of Er preferably is controlled at 0.05 ~ 0.15wt.%, when being higher than this scope, because the rare earth element chemical property is active, is easy to form rare earth compound, reduces the wetability of solder alloy; Also can reduce the intensity and the plasticity of alloy.In this scope, alloying element helps crystal grain thinning, wetability, improves the bond strength of welding procedure yield and solder joint.
Description of drawings
Fig. 1 is differential scanning calorimetry (DSC) analytic curve of embodiment 1,2,3 scolder samples.
Fig. 2 is the stress strain curve of the Cu/ scolder/Cu solder joint of embodiment 1 and comparative example.
The specific embodiment
The preparation of embodiment 1 Sn-1.5Ag-0.3Cu-3.0Bi-0.05Er
By each component weight percentage proportioning, Ag is 1.5%, and Cu is 0.3%, and Bi is 3.0%, and Er is 0.05%, and surplus is Sn.
Its preparation process is: in vacuum arc melting furnace, prepare Sn-10Er intermediate alloy 50g by weight ratio; Pure Sn that weighs up and Er are mixed, in vacuum arc furnace ignition, be heated to 1600 ℃, stir fusing, cool off behind the insulation 30min, the button ingot is processed in melt back 3 times.Take by weighing 0.5g Sn-10Er intermediate alloy, 1.5g Ag, 0.3g Cu, 3.0g Bi and 94.7g Sn; Fully mix to be placed on and carry out 900 ℃ of high melts in the vacuum induction melting furnace, insulation 30min is to guarantee to make the homogeneity of ingredients of alloy; Is 300 ℃ of following vacuum remeltings with the gained solder alloy in temperature,
Insulation 1h, air cooling subsequently, it is subsequent use to make the scolder ingot blank.
The preparation of embodiment 2 Sn-1.0Ag-0.3Cu-3.0Bi-0.05Er
By each component weight percentage proportioning, Ag is 1.0%, and Cu is 0.3%, and Bi is 3.0%, and Er is 0.05%, and surplus is Sn.
Its preparation method is as embodiment 1.
The preparation of embodiment 3 Sn-2.0Ag-0.3Cu-3.0Bi-0.05Er
By each component weight percentage proportioning, Ag is 2.0%, and Cu is 0.3%, and Bi is 3.0%, and Er is 0.05%, and surplus is Sn.
Its preparation method is as embodiment 1.
The preparation of embodiment 4 Sn-1.5Ag-0.3Cu-2.5Bi-0.05Er
By each component weight percentage proportioning, Ag is 1.5%, and Cu is 0.3%, and Bi is 2.5%, and Er is 0.05%, and surplus is Sn.
Its preparation method is as embodiment 1.
The preparation of embodiment 5 Sn-1.0Ag-0.3Cu-2.5Bi-0.05Er
By each component weight percentage proportioning, Ag is 1.0%, and Cu is 0.3%, and Bi is 2.5%, and Er is 0.05%, and surplus is Sn.
Its preparation method is as embodiment 1.
The preparation of embodiment 6 Sn-2.0Ag-0.3Cu-2.5Bi-0.05Er
By each component weight percentage proportioning, Ag is 2.0%, and Cu is 0.3%, and Bi is 2.5%, and Er is 0.05%, and surplus is Sn.
Its preparation method is as embodiment 1.
The preparation of embodiment 7 Sn-1.5Ag-0.3Cu-3.0Bi-0.1Er
By each component weight percentage proportioning, Ag is 1.5%, and Cu is 0.3%, and Bi is 3.0%, and Er is 0.1%, and surplus is Sn.
Its preparation method is as embodiment 1.
Comparative example Sn-3.0Ag-0.5Cu
By each component weight percentage proportioning, Ag is 3%, and Cu is 0.5%, and surplus is Sn
The performance of the embodiment of the invention 1,2,3 and comparative example is seen table 1.
The performance of table 1 Sn-Ag-Cu-Bi-Er scolder and SAC305 scolder relatively
Can find out from table 1: the more original Sn-3.0Ag-0.5Cu scolder of scolder according to the invention has lower fusing point, and change in resistance is little; And under same experimental conditions, the spreading area of embodiment 1 is maximum, explains that its wetability is good.
Fig. 1 is differential scanning calorimetry (DSC) analytic curve of present embodiment 1,2,3 scolder samples, and the melting characteristic of visible Sn-1.5Ag-0.3Cu-3.0Bi-0.05Er scolder is best from figure.
Fig. 2 is the tensile property of the Cu/ scolder/Cu solder joint of Sn-Ag-Cu-Bi-Er scolder of the present invention; Contrast Cu/Sn3.0Ag0.5Cu/Cu solder joint, its hot strength has decline slightly, but percentage elongation becomes big.
In conjunction with the tensile property of solder performance and Cu/ scolder/Cu solder joint, the combination property of Sn-1.5Ag-0.3Cu-3.0Bi-0.05Er scolder of the present invention is best.
Claims (3)
1. Sn-Ag-Cu-Bi-Er low-silver lead-free solder, it is characterized in that having following each component and percentage by weight: Ag is 0.3-2.0%, and Cu is 0.3-0.7%, and Bi is 2.0-3.0%, and Er is 0.01-0.15%, surplus is Sn;
The purity of each component metals raw material is respectively: Bi >=99.99%, Er >=99.9%, Ag >=99.99%, Cu >=99.99%, Sn >=99.99%.
2. a kind of Sn-Ag-Cu-Bi-Er low-silver lead-free solder according to claim 1 is characterized in that the preferred group of this scolder becomes: Ag is 1.0-2.0%, and Cu is 0.3-0.5%, and Bi is 2.0-3.0%, and Er is 0.05-0.10%, and surplus is Sn.
3. the preparation method of a Sn-Ag-Cu-Bi-Er low-silver lead-free solder is characterized in that it being that following process is arranged: at first under vacuum state, adopt existing method of smelting heating melting to prepare the Sn-10Er intermediate alloy; Get the concrete content of Er through chemical analysis after, be converted into the weight of Sn-Er intermediate alloy and each component and be prepared into the solder alloy ingot blank by above-mentioned weight proportion.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102962600A (en) * | 2012-12-14 | 2013-03-13 | 上海华庆焊材技术有限公司 | Multi-element alloy lead-free soldering flux |
| CN104289824A (en) * | 2014-09-30 | 2015-01-21 | 济南无线电十厂有限责任公司 | Stannum, argentum and copper lead-free solder and production method thereof |
| CN105945447A (en) * | 2016-06-28 | 2016-09-21 | 江苏阳明船舶装备制造技术有限公司 | SnAgCu-series lead-free brazing filler metal and preparation method |
| CN114289927A (en) * | 2021-12-28 | 2022-04-08 | 上海大学 | Lead-free solder |
| CN114559178A (en) * | 2021-12-21 | 2022-05-31 | 西安理工大学 | Sn-Bi-Ag series lead-free solder and preparation method thereof |
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| CN1621194A (en) * | 2004-12-17 | 2005-06-01 | 北京工业大学 | Rare earth contained SnAgCuEr tin based leadless solder and its preparation method |
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| CN101733576A (en) * | 2009-11-26 | 2010-06-16 | 上海大学 | Sn-Ag-Cu-Bi-Cr quinary alloy lead-free solder |
| CN101850480A (en) * | 2009-03-31 | 2010-10-06 | 宁波银羊焊锡材料有限公司 | Lead-free solder |
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| CN1689751A (en) * | 2004-04-24 | 2005-11-02 | 叶志龙 | Plumbum-free soldering tin |
| CN1621194A (en) * | 2004-12-17 | 2005-06-01 | 北京工业大学 | Rare earth contained SnAgCuEr tin based leadless solder and its preparation method |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102962600A (en) * | 2012-12-14 | 2013-03-13 | 上海华庆焊材技术有限公司 | Multi-element alloy lead-free soldering flux |
| CN104289824A (en) * | 2014-09-30 | 2015-01-21 | 济南无线电十厂有限责任公司 | Stannum, argentum and copper lead-free solder and production method thereof |
| CN105945447A (en) * | 2016-06-28 | 2016-09-21 | 江苏阳明船舶装备制造技术有限公司 | SnAgCu-series lead-free brazing filler metal and preparation method |
| CN114559178A (en) * | 2021-12-21 | 2022-05-31 | 西安理工大学 | Sn-Bi-Ag series lead-free solder and preparation method thereof |
| CN114289927A (en) * | 2021-12-28 | 2022-04-08 | 上海大学 | Lead-free solder |
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Application publication date: 20120620 |