CN100445018C - Lead-free solder - Google Patents
Lead-free solder Download PDFInfo
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- CN100445018C CN100445018C CNB2006100371365A CN200610037136A CN100445018C CN 100445018 C CN100445018 C CN 100445018C CN B2006100371365 A CNB2006100371365 A CN B2006100371365A CN 200610037136 A CN200610037136 A CN 200610037136A CN 100445018 C CN100445018 C CN 100445018C
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Abstract
The invention relates to a tin-zinc base non-lead soft solder with mixed rare earth, wherein it comprises Sn and Xn, and adds Bi, Co, and lanthanide series mixed rare earth on said tin-zinc base; the Zn is at 1.0-12.0%, Bi is 0.5-6%, Co is 0.001-2.0%, lanthanide series mixed rare earth is 0.01-1.2% and left is Sn. The invention can improve the non-lead solder, to obtain electric level, with uniform organism, better welding property and high anti-oxygen property. And it has low fusion point and low cost.
Description
Technical field:
The invention belongs to metal material, relate to the electronics brazing material field, refer in particular to a kind of tin-zinc-based leadless soft solder that mixes rare earth that contains.
Background technology:
Have many metals and alloy to cause very big harm for the mankind and environment in actual applications, people's environmental consciousness is strengthened having promoted industry to adjust accordingly.In electronic industry, many countries have just put into effect corresponding laws and regulations and have reduced the harm of its discarded object to environment.For example, on July 1st, 2006, the ROHS of European Union instruction is formally implemented, and all enterprises relevant with the European market electronic product all must reach its requirement, and this will impel electronic material further to accelerate to unleaded conversion.People have developed many lead-free solders, but existing lead-free solder also exists such as problems such as fusing point height, easily oxidation, cost height.
Silver is the poorest metal of corrosion resistance in the noble metal, and SAC alloy strength and wetability in the practical application are poor, and fusing point height and oxidation resistance is poor will produce many defectives.Requirement from soft pricker industry, the fusing point of unleaded cored solder is low, as far as possible near 183 ℃ of the eutectic temperatures of 63/37 leypewter, but SnAg3.5Cu0.5 alloy in Sn-Ag (Cu) series commonly used at present, its eutectic temperature is 217 ℃, fusing point still is higher, and intensity, wetability are relatively poor, remains further to be improved.
Use Bi in lead-free solder, Zn etc. can form the metal of eutectic point alloy with tin, can reduce the fusing point of scolder, but the mechanical property of these scolders existing problems, as poor ductility, thermal shock resistance difference etc.In addition, use low-melting metals such as Zn, Bi to fire lead-free solder, also have the problem of the easy oxidation in active metal.Therefore, seek that preparation technology is simple, well behaved lead-free solder and preparation method thereof is this area research personnel's goal in research.
Though tin zinc series alloy has certain defective, especially aspect non-oxidizability and mechanical property, the fusing point of SnZn and SnPb alloy is the most approaching, and cost is lower, so always be one of focus that domestic and international industry personage pays close attention to.This solves Welding Sn-Zn material system and sprawls the relatively poor problem of manufacturability, and with regard to the U.S., its relevant expert just explores in continuous research always, attempts to seek new valuable lead-free solder.U.S. Pat 5698160 (August 29 1996 applying date, open day on December 16th, 1997) record is the SnZnNiAgCu alloy, choosing adds a certain amount of Bi or In, this solder contains the Zn of 7-10%, the Ag of 0.1-3.5%, solder far departs from the SnZn eutectic composition, causes the solder molten temperature region big.The soldering difficulty, Ag content is big simultaneously, the cost height; That put down in writing is SnZnBi to U.S. Pat 5942185 (October 18 1997 applying date, open day on August 24th, 1999).This solder contains the Zn of 3-5%, and the Bi of 10-23% causes molten temperature region to surpass 30 ℃, and big like this molten temperature region has caused the soldering difficulty equally, and solder becomes fragile, and percentage elongation is low, is difficult for being drawn into welding wire; That put down in writing is SnZnBiGe to U.S. Pat 6503338 (April 28 2000 applying date, open day on January 7th, 2003), and P or Ge add as deoxidier, Bi content in this solder is at 2-15%, when Bi content was higher than 6%, the percentage elongation of solder obviously descended, and solder becomes fragile; U.S. Pat 6649127 (March 21 calendar year 2001 applying date, open day on November 18th, 2003) in the SnZn series alloy, add the manufacturability of sprawling that Bi, Ge, Cu or Bi, Ge, Ag, Cu improve the SnZn solder, but this patent alloy constituent element is many, the smelting process difficulty, the Cu that adds 0.3-3% or 0.3-1% simultaneously in the SnZn alloy, may produce the Sn6Cu5 intermetallic compound, make the joint of solder become fragile reliability decrease; U.S. Pat 6488888 (April 9 calendar year 2001 applying date, open day on December 3rd, 2002) be SnZnNiAgCu, this alloy can cause the solder molten temperature region to surpass 50 ℃ when selecting the Bi too high levels that adds, big like this molten temperature region can make the soldering difficulty, and solder becomes fragile, percentage elongation is low, is difficult for being drawn into silk.
Because there are many insoluble problems in tin zinc series alloy, has once once been treated coldly a period of time.But the intrinsic advantage of tin zinc series alloy makes it become one of focus of concern again, and in recent years, external many research institutions have all dropped into more manpower and financial resources in this regard.
In the past, the researcher had developed ternary and multi-component leadless alloys such as SnZnIn, SnZnAg, SnZnAl, SnZnBi and SnZnRe on SnZn eutectic alloy basis.With binary SnZn be the alloy phase ratio, the wettability of these alloys improves to a certain extent, but also has many defectives, does not still reach the level of SnPb scolder.
Summary of the invention:
Purpose of the present invention provides a kind of fusing point low just in order to overcome the defective of prior art, the relative better tin-zinc-based leadless soft solder that mixes rare earth that contains of mechanical property with wellability, and its non-oxidizability significantly improves, and the solder joint surface smoothness is obviously improved.
Another purpose of the present invention provides a kind of microstructure thinning, even, and cost is low, can extensively be fit to the tin-zinc-based leadless soft solder that mixes rare earth that contains of electron trade solder use.
For achieving the above object, the present invention is achieved through the following technical solutions: a kind of tin-zinc-based leadless soft solder that mixes rare earth that contains, on the basis of Sn and Zn, also be added with Bi, Co and group of the lanthanides mishmetal, weight ratio is the Zn of 1.0-12.0%, the Bi of 0.5-6%, the Co of 0.001-2.0%, the group of the lanthanides mishmetal of 0.01-1.2%, surplus is Sn.
The contrast prior art, the present invention adds Bi, Co and a small amount of group of the lanthanides mishmetal on the tin zinc-base, thereby improves lead-free solder tissue and performance, obtains the electron level lead-free solder.Its microstructure thinning, even has good electrical mechanism performance and welding performance; Its fusing point is low simultaneously, and cost is less, can extensively be fit to the electron trade solder and use.
The specific embodiment:
The tin-zinc-based leadless soft solder that mixes rare earth that contains of the present invention, consist predominantly of Sn and Zn, on the tin zinc-base, also add Bi, Co and group of the lanthanides mishmetal, weight ratio is the Zn of 1.0-12.0%, the Bi of 0.5-6%, the Co of 0.001-2.0%, the group of the lanthanides mishmetal of 0.01-1.2%, surplus is Sn.
In lead-free solder, use Bi, Zn etc. can form the metal of eutectic point alloy, can reduce the fusing point of scolder with tin.The present invention is also by interpolation Co, and micro-mishmetal component, thereby improves the method for lead-free solder performance, makes this low-melting-point metal scolder can possess mechanical property, wellability and non-oxidizability preferably.The inventive method manufacturability and functional improves weld strength and solder joint plastic deformation performance, can be used for being connected of electronic circuit and device.
The content that SnZn series leadless solder provided by the invention, this solder have following characteristics: Zn is controlled between the weight ratio 1.0-12.0%, and adds a spot of Bi, makes the molten temperature region of alloy little, and the soldering processes performance is better.The Zn percentage by weight is lower than 1.0% or surpass 12.0%, all can make alloy away from eutectic composition, and it is big that molten temperature region becomes, and makes welding that difficulty take place; The adding of Bi element improves the processing performance of sprawling of solder, and spreading area increases, and simultaneously a small amount of Bi increases the tensile strength of solder, but that percentage elongation falls is little, can satisfy the requirement of existing microelectronics surface-assembled fully; And Co (cobalt) can make the institutional framework of scolder become more meticulous, add cobalt and can also improve solderability in tin zinc bismuth solder, Co content of the present invention is at 0.001-2.0%, by a spot of group of the lanthanides mishmetal of further interpolation, further improve the percentage elongation of solder, make solder be easy to be drawn into welding wire.Mishmetal Re content should be lower than 1.2%, if surpass 1.2%, generates the fragility phase on the contrary easily, makes the solder embrittlement.Lead-free brazing provided by the present invention can be used for manual welding, wave-soldering and the reflow soldering process of microelectronics assembling, substitutes leaded SnPb solder.
If the measurement of performance is carried out according to GB GB 229.87, adopt the tension test standard of lead-free solder.Test result shows that the mechanical property of novel lead-free scolder of the present invention and wellability have tangible improvement.For containing secret solder hierarchy, add the elongation after fracture that some trace meters help improving scolder, thereby improve the performance of its plastic deformation.For the solder hierarchy that contains Zn, add the mechanical property that trace meter can improve scolder, comprise ultimate tensile strength, elongation after fracture and regulation disproportional elongation stress.Trace doped metal can not only improve part mechanical property and wellability, can also play the effect of the nuclei of crystallization in welding process, thereby prevents the generation of large scale intermetallic compound.Because the large scale intermetallic compound is the main predisposing factors of scolder fracture, therefore, this is to reducing the solder joint that lost efficacy easily in the industrial production, and it is significant improving the device global reliability.
The present invention be chosen on the tin zinc-base add other trace element mainly be the fusing point of tin zinc system very near the plumbous eutectic of tin, and tin, zinc is easy to get, cost is lower.
Zinc is very cheap, and almost the price with lead is identical, and can obtain at any time, and it also has very high efficient aspect the fusing point that reduces ashbury metal simultaneously.Yet because zinc has higher activity, its alloy is easy to take place oxidation in air.Perhaps will be overcoming these technology barriers by deactivation or extraordinary flux composition, but people require to prove containing the zinc scheme in bigger processing range now.
The zinc of certain content can make the solder fusing point reduce, if but the weight of Zn is too high, and greater than 12% o'clock, can cause the scolder fusing point to rise, and the temperature difference between the solid-liquid phase line strengthen.If the percentage by weight of Zn, does not then reach the effect that reduces fusing point less than 1.0%, and can cause the reduction of mechanical strength.
The present invention adds a certain amount of bismuth, can significantly improve the wetability of scolder, reduces the fusing point of scolder, and certain corrosion resistance is arranged.
Bismuth has excellent wetting capacity matter and better physical character, in that to reduce ashbury metal also apparent in view because of effect aspect the phase temperature, but liquidus temperature is not had such effect, therefore may cause bigger solid-liquid coexistence temperature range, and the too big leg that may cause of solidification temperature range promotes.
Non-eutectic alloy can solidify in a certain temperature range between liquidus temperature and solid-state temperature, and most of metallurgical expert advices are controlled at this temperature range in 10 ℃, so that form good solder joint, reduces defective.If the solder joint cracking then might take place in the alloy graining wider range.
Bismuth further reduces the solder fusing point, and wetability improves, and corrosion resistance is slightly improved.But the metal Bi of the weight proportion above 6% can play negative effect to the reliability of Welding Sn-Zn material.In experimentation, when we find that Bi content is higher, can segregation phenomena take place and cause solder joint to be peeled off; But (less than 0.5%) does not then have the effect that reduces fusing point when too low as if Bi content.
It mainly is that Co can crystal grain thinning and improve the mechanical property of soldering that the present invention introduces the Co element, improves the solderability of scolder simultaneously.
The condensation cured temperature height of cobalt, and by add cobalt in tin after, cobalt becomes nucleus, thereby the institutional framework of scolder is become more meticulous.In tin zinc bismuth solder, add cobalt and can also improve its solderability.In the present invention, the content of cobalt is chosen between the 0.001%-2.0%, and the wetability of lead-free alloy will weaken when being lower than this scope.When the addition of cobalt during greater than 2.0wt%, the fusing point of scolder can raise in addition; When simultaneously Co is too high, will and Sn between form bigger intermetallic compound, and cause the separation of solid-liquid phase line.The metal that the present invention adds trace can improve the mechanical properties such as elastic modelling quantity, elongation after fracture, regulation disproportional elongation stress of lead-free solder.
According to solid and molecular electronic theory, Co can increase the dark admittedly body atomic binding forces of tin zinc bismuth.Simultaneously, Co has also changed the valence electron structure of the inclined to one side poly structure unit of other alloying elements formation, thereby changed the mechanism of separating out of second phase under certain operating temperature, strengthened the thermal fatigue resistance of soldering, and reduced the angle welding that projection on via devices, occurs.
It mainly is in order to promote the microalloying of alloy, to improve the wetability and the non-oxidizability ability of scolder that the present invention introduces the group of the lanthanides mishmetal.
The phasor (as the solubility of rare earth element in metal) of rare earth and base metal is depended in the microalloying effect of rare earth element, the character of rare earth compound, shape and distribution, distribution and the diffusion velocity of rare earth in metal, and rare earth is to the distribution of other alloying element and the influence of diffusion velocity etc.
Rare earth is good alterant, also is a kind of potent microalloy element.The preliminary identification of microalloying effect of rare earth element mainly is rare earth atom poly-partially and other elemental interactions on crystal boundary, cause the variation of structure, chemical composition and the energy of crystal boundary, and the nucleation that influences other elemental diffusion and cenotype with grow up, finally cause the variation of scolder microstructure and property.Therefore the adding of group of the lanthanides mishmetal, its favourable effect is many-sided, the toughness of soldering obviously improves, and has improved the decay resistance of soldering simultaneously.
Institute adds group of the lanthanides mishmetal rare earth and has the microalloying effect, certain solid solution capacity is arranged in solder, it suppresses phosphorus sulphur and low melting point impurity lead, arsenic at the inclined to one side cumulative of crystal boundary, antimony forms the higher compound of fusing points in the segregation of crystal boundary or with these impurity, eliminates the illeffects of low melting point impurity.Rare earth can purify and strengthen crystal boundary simultaneously, hinders the formation and the expansion of intercrystalline crack, helps improving plasticity.
Add micro-mishmetal and also significantly improved the non-oxidizability of scolder, make the oxide layer surface fine and close more simultaneously, scolder is difficult for by further oxidation, thereby has significantly improved the oxidation resistance of scolder.
The group of the lanthanides mishmetal adds the tin-zinc-based leadless solder alloy that forms, and wetting moist significantly raising is organized finer and closely woven.
In addition, in the alloy smelting process, always have the impurity of trace, the group of the lanthanides mishmetal adds wherein can play catharsis, has reduced the adverse effect of impurity greatly.
Alloy scheme of the present invention is: the interpolation scope of Zn is 1.0-12%, and the interpolation scope of Bi is 0.5-6%, and the interpolation scope of Co is 0.001-2.0%, and the interpolation scope of group of the lanthanides mishmetal is 0.01-1.2%, and surplus is Sn.
The scolder that the present invention obtains, the volume shrinkage factor is minimum between its mushy stage, can be similar to think solid Volume is constant between liquid state, simultaneously because the thermal coefficient of expansion of this scolder is little, so its reliability with Other alloy phase ratio has significantly raising. This scolder has good processing characteristics, postwelding solder joint table Surface evenness and bright and clean all have significantly improve, be suitable for multiple microelectronic processing technology.
Claims (2)
1, lead-free solder consists predominantly of Sn and Zn, it is characterized in that: this lead-free solder also includes Bi, Co and group of the lanthanides mishmetal, weight ratio is the Zn of 1.0-12.0%, 0.5% Bi, the Co of 0.001-2.0%, 1.2% group of the lanthanides mishmetal, surplus are Sn.
2, lead-free solder according to claim 1 is characterized in that: the weight ratio of Zn gets 1.0%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100371365A CN100445018C (en) | 2006-08-16 | 2006-08-16 | Lead-free solder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100371365A CN100445018C (en) | 2006-08-16 | 2006-08-16 | Lead-free solder |
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| Publication Number | Publication Date |
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| CN1907634A CN1907634A (en) | 2007-02-07 |
| CN100445018C true CN100445018C (en) | 2008-12-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB2006100371365A Expired - Fee Related CN100445018C (en) | 2006-08-16 | 2006-08-16 | Lead-free solder |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017221425A1 (en) * | 2016-06-24 | 2017-12-28 | 朝日インテック株式会社 | Guide wire |
| CN106624433A (en) * | 2016-11-30 | 2017-05-10 | 安徽华众焊业有限公司 | Low-melting-point lead-free solder alloy |
| JP6344541B1 (en) * | 2017-08-17 | 2018-06-20 | 千住金属工業株式会社 | Fe erosion prevention solder alloy, cored wire solder, wire solder, cored wire solder, flux coated solder, and solder joint |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1390672A (en) * | 2002-05-10 | 2003-01-15 | 大连理工大学 | Leadfree SnZn-base alloy solder containing rare-earth elements |
| CN1400081A (en) * | 2001-06-28 | 2003-03-05 | 千住金属工业株式会社 | Lead-free welding flux alloy |
| JP2003275891A (en) * | 2002-03-22 | 2003-09-30 | Fujitsu Ltd | Solder paste, junction obtained by using the solder paste and electronic equipment provided with the junction |
| CN1586793A (en) * | 2004-07-16 | 2005-03-02 | 北京工业大学 | SnZn series lead-free welding flux |
| CN1673401A (en) * | 2004-03-23 | 2005-09-28 | 金庚大 | Low temperature leadless alloy |
| JP2005288478A (en) * | 2004-03-31 | 2005-10-20 | Toshiba Corp | Lead-free solder weld |
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2006
- 2006-08-16 CN CNB2006100371365A patent/CN100445018C/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1400081A (en) * | 2001-06-28 | 2003-03-05 | 千住金属工业株式会社 | Lead-free welding flux alloy |
| JP2003275891A (en) * | 2002-03-22 | 2003-09-30 | Fujitsu Ltd | Solder paste, junction obtained by using the solder paste and electronic equipment provided with the junction |
| CN1390672A (en) * | 2002-05-10 | 2003-01-15 | 大连理工大学 | Leadfree SnZn-base alloy solder containing rare-earth elements |
| CN1673401A (en) * | 2004-03-23 | 2005-09-28 | 金庚大 | Low temperature leadless alloy |
| JP2005288478A (en) * | 2004-03-31 | 2005-10-20 | Toshiba Corp | Lead-free solder weld |
| CN1586793A (en) * | 2004-07-16 | 2005-03-02 | 北京工业大学 | SnZn series lead-free welding flux |
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| CN1907634A (en) | 2007-02-07 |
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Address after: 523808 Guangdong province Dongguan City Songshan Lake Science and Technology Industrial Park Keyuan song library building B Room 201 Patentee after: Perfection Science and Technology (Dongguan) Co., Ltd. Address before: 523000 academic exchange center of Songshan Lake Science and Technology Industrial Park, Guangdong, Dongguan 308 Patentee before: Dongguan Professional Surface Technology Co., Ltd. |
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