CA2541637A1 - Pb-free solder alloy compositions comprising essentially tin (sn), silver (ag), copper (cu), phosphorus (p) and rare earth: cerium (ce) or lanthanum (la) - Google Patents
Pb-free solder alloy compositions comprising essentially tin (sn), silver (ag), copper (cu), phosphorus (p) and rare earth: cerium (ce) or lanthanum (la) Download PDFInfo
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- CA2541637A1 CA2541637A1 CA 2541637 CA2541637A CA2541637A1 CA 2541637 A1 CA2541637 A1 CA 2541637A1 CA 2541637 CA2541637 CA 2541637 CA 2541637 A CA2541637 A CA 2541637A CA 2541637 A1 CA2541637 A1 CA 2541637A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C13/00—Alloys based on tin
Abstract
A Pb-free solder alloy is designed from the Sn based substrate, which is a non-toxic and environmental friendly metal. The Pb-free solder includes a composition consisting essentially of 0.3 - 0.4 weight % Ag, 0.6 - 0.7 weight % Cu, 0.01 - 0.3 weight % P, 0.001 - 0.3 weight % Ce, optionally 0.001 - 0.3 weight % La, and a balance of Sn, having off--eutectic melting temperatures of about 217-227 degree Celsius.
0.001 - 0.3 weight % Trace amount of Ce and / or La rare earth added to the said composition, to enhance better micro-structural stability and to reduce the coarse Sn grains in the microstructure of the solder joint formed, during Hand Soldering, Wave Soldering and Reflow Soldering in Electronics Assembly Processes.
0.001 - 0.3 weight % Trace amount of Ce and / or La rare earth added to the said composition, to enhance better micro-structural stability and to reduce the coarse Sn grains in the microstructure of the solder joint formed, during Hand Soldering, Wave Soldering and Reflow Soldering in Electronics Assembly Processes.
Description
Pb-free Solder Alloy Compositions Comprisinn Essentially Tin (Sn), Silver (Ag), Copper (Cu), And Phosphorus (P) With Rare Earth: Cerium (Ce) or Lanthanum (La) Background of the Invention 1. Field of the Invention Despite Pb is a component of solder alloys in widespread use in the electronic industry, there is a drive to replace the use of Pb metal, because of its toxic nature. In addition to the toxicity of Pb, there are other problems concerning continued widespread use of the Sn-Pb and Pb-based solders. In United States, Canada, most of the Europe, and in Japan, the use of Pb in all commercial products, such as: vehicles, electronic toys, computers and appliances, shall all be banned.
2. Description of the Prior Art The excellent metallurgical wetting of 63% Sn and 37% Pb is thought to be promoted by the instantaneous formation of a thin layer of a very stable intermetallic compound at the molten solder interface. The interfacial inter-metallic compound that aids solder wetting is always based on Sn, not Pb. The role of Pb in promoting solderability is much less understood, but seems related to its ability to strongly suppress the liquid surface tension of the solder alloy, lowering the contact angel of the molten solder which leads to better spreading and more interacting surface area for the solder joint to form. The eutectic solidification reaction of 63% Sn and 37% Pb also generates a highly refined mixture of Sn and Pb phases that produces unusual strength from rather weak constituents.
In response to the possibility of a governmental ban or excessive taxation of Pb use, manufacturers and users of Pb-bearing solder for electronic and circuit joining applications recently have attempted to developed Pb-free solders as direct replacements for the conventional Sn-Pb solders in conventional hand/wave/reflow soldering processes employing general heating of an electronic wiring board to temperatures of 240-degree Celsius. Moreover, there is a need for such a solder that would be competitive in cost and as readily available as conventional Sn-Pb eutectic solders for high volume use.
A ternary, off-eutectic Sn-Ag-Cu solder alloy has been developed by the plumbing industry as a Pb-free solder with 96 weight % Sn, 3.5 weight % Cu, and 0.5 weight % Ag. This plumbing solder has a 227 degree Celsius of solidus temperature and 260 degree Celsius liquidus temperature, which would be considered not suitable for electronics manufacturers.
Recent developments of Pb-free solder alloys mainly involve the use of Ag, Bi, Cu, In, Sn, and Zn. Special attentions have been drawn on the solder composition comprising Sn, Ag, and Cu. Anderson et. al. of Iowa State University Research have reported the eutectic Pb-free solder comprising 93.6Sn/4.7Ag/1.7Cu and Sn/Ag/Cu/Ni/Fe, respectively.
Summary of the Invention This present invention provides a Pb-free solder comprising a compositions consisting essentially of Sn, Ag, Cu, P, and Ce or La, having a melting temperature of degree Celsius.
In one embodiment of the invention, the Pb-free solder consists essentially of 0.3 weight % Ag, 0.7 weight % Cu, 0.05 weight % P, 0.001-0.3 weight % Ce or La, and balance of weight % Sn. To the Sn/0.3Ag/0.7Cu/0.05P, 0.001 to 0.3 weight % of Ce or La is added to improve better micro-structural stability and hence reduce grain size of Sn in the solder composition, and the melting temperature is 217-227 degree Celsius.
In another embodiment of the invention, the Pb-free solder consists essentially of 0.4 weight % Ag, 0.6 weight % Cu, 0.05 weight % P, 0.001-0.3 weight % Ce or La, and balance of weight % Sn. To the Sn/0.4Ag/0.6Cu/0.05P, 0.001 to 0.3 weight % Ce or La is added to improve better micro-structural stability and hence reduce grain size of Sn in the solder composition, and the melting temperature is 217-227 degree Celsius.
The solder of the invention described here-above can be used as a replacement for Pb-containing solder in solder wave and other hand soldering processes in widespread use in the electronic and other industries.
The solder of the invention is advantageous not only from an environmental standpoint but also from the cost and availability standpoint in that the alloy compounds (Sn, Ag, Cu and P) are readily available at lower cost than the Pb-free solders including large amount of Bi, In, Zn, or Ga proposed to-date. Large volume solder applications especially will benefit from the low cost, high performance solder of the invention having the aforementioned advantages not possesses heretofore by other Pb-free solders.
The above brief description sets forth rather broadly the more important features of the present invention in order that the detailed description thereof that follows may be better understood, and in order that the present contributions to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and will form the subject matter of the claims appended hereto.
In this respect, before explaining the preferred embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood, that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for designing other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing Abstract is to enable the Intellectual Property Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms of phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, the Abstract is neither intended to define the invention or the application, which only is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
It is therefore an object of the present invention to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which has all of the advantages of the prior art and yet keep our environment green.
It is another object of the present invention to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which may be efficiently manufactured and marketed.
An even further object of the present invention is to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to the consuming public, thereby making such composition available to the buying public.
Still yet a further object of the present invention is to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which can be used to make Pb-free solder bar, wire, paste, BGA ball and anode in electronics industries.
These together with still other objects of the invention, along with the various features of novelty, which characterize the invention, are pointed out with particularity in the claims forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be made to the following detailed description of the preferred embodiments of the invention.
Description of the preferred Embodiment The Pb-free solder of the present invention is based on a composition essentially of about 0.3-0.4 weight % Ag, 0.6-0.7 weight % Cu, 0.01-0.3 weight % P, 0.001-0.3 weight % Ce or La, and balance weight % Sn, with the additional of Ce or La, not exceeding 0.3 weight % of the overall composition, to enhance better micro-structural stability and to reduce grain size of the resultant solder joints.
Preferably, for electronic solder applications using the solder wave process, the melting temperature range of the solder should not exceed 10 degree Celsius. This present invention has a solder melting range of 10 degree Celsius.
A preferred Pb-free solders of the invention are listed below, exhibiting off-eutectic melting temperatures:
(1). A electrical conductor Pb-free solder composition consisting essentially of 0.3 %
weight % Ag, 0.7 weight % Cu, 0.01-0.3 weight % P, 0.001-0.3 weight % Ce or La, balance Sn and unavoidable impurities, based on the weight of composition.
The melting temperature of the solder is in the range of 217 to 227 degree Celsius.
(2). A electrical conductor Pb-free solder composition consisting essentially of 0.4 %
weight % Ag, 0.6 weight % Cu, 0.01-0.3 weight % P, 0.001-0.3 weight % Ce or La, balance Sn and unavoidable impurities, based on the weight of composition.
The melting temperature of the solder is in the range of 217 to 227 degree Celsius.
The Pb-free solder of the present invention includes at least one non-metallic component consisting essentially of P, in an amount not exceeding 0.3 weight %.
The Pb-free solder of the present invention, which comprises Sn/(0.3-0.4)Ag/(0.6-0.7)Cu/(not exceeding 0.3)P/(0.001-0.3)Ce or La, is similar as the conventional Pb-free solder comprising Sn/3.OAg/0.5Cu in welding performance, conductivity, mechanical property, pliability and so on. But since the content of Ag of the Pb-free solder of the present invention is about one-tenth of other Pb-free solder comprising Sn/3.OAg/0.5Cu (Ag is trend to react with chemical agents, such as acid or alkali and so on, thereby to produce noxious substance), so the Pb-free solder of the present invention is more safe, and has no adverse effect to living beings and environments in potential. In addition, the content of Ag [less than 0.5%] of the Pb-free solder of the present invention, which comprises Sn/(0.3-0.4)Ag/(0.6-0.7)Cu/(not exceeding 1.0)P/(0.001-0.3)Ce or La, is less than that of conventional Pb-free SnAgCu solder, so the silver compounds which are generated in the reaction between silver and halogen component of the soldering flux, are not easy to form, as a result, the phenomenon of changing to black is slight.
The method for preparing 500 Kg of the Pb-free solder of the present invention is shown below:
1. 3.5 Kg of pure copper, 250 g Ce or La and 200 Kg of pure tin are added into a steel kettle, then heated to the temperature of 400 degree Celsius, and stirred for about 45 minutes;
2. The resulting mixture is cooled to the temperature of 300 degree Celsius, then 294.5 Kg pure tin is added into the steel kettle and stirred for about 45 minutes;
In response to the possibility of a governmental ban or excessive taxation of Pb use, manufacturers and users of Pb-bearing solder for electronic and circuit joining applications recently have attempted to developed Pb-free solders as direct replacements for the conventional Sn-Pb solders in conventional hand/wave/reflow soldering processes employing general heating of an electronic wiring board to temperatures of 240-degree Celsius. Moreover, there is a need for such a solder that would be competitive in cost and as readily available as conventional Sn-Pb eutectic solders for high volume use.
A ternary, off-eutectic Sn-Ag-Cu solder alloy has been developed by the plumbing industry as a Pb-free solder with 96 weight % Sn, 3.5 weight % Cu, and 0.5 weight % Ag. This plumbing solder has a 227 degree Celsius of solidus temperature and 260 degree Celsius liquidus temperature, which would be considered not suitable for electronics manufacturers.
Recent developments of Pb-free solder alloys mainly involve the use of Ag, Bi, Cu, In, Sn, and Zn. Special attentions have been drawn on the solder composition comprising Sn, Ag, and Cu. Anderson et. al. of Iowa State University Research have reported the eutectic Pb-free solder comprising 93.6Sn/4.7Ag/1.7Cu and Sn/Ag/Cu/Ni/Fe, respectively.
Summary of the Invention This present invention provides a Pb-free solder comprising a compositions consisting essentially of Sn, Ag, Cu, P, and Ce or La, having a melting temperature of degree Celsius.
In one embodiment of the invention, the Pb-free solder consists essentially of 0.3 weight % Ag, 0.7 weight % Cu, 0.05 weight % P, 0.001-0.3 weight % Ce or La, and balance of weight % Sn. To the Sn/0.3Ag/0.7Cu/0.05P, 0.001 to 0.3 weight % of Ce or La is added to improve better micro-structural stability and hence reduce grain size of Sn in the solder composition, and the melting temperature is 217-227 degree Celsius.
In another embodiment of the invention, the Pb-free solder consists essentially of 0.4 weight % Ag, 0.6 weight % Cu, 0.05 weight % P, 0.001-0.3 weight % Ce or La, and balance of weight % Sn. To the Sn/0.4Ag/0.6Cu/0.05P, 0.001 to 0.3 weight % Ce or La is added to improve better micro-structural stability and hence reduce grain size of Sn in the solder composition, and the melting temperature is 217-227 degree Celsius.
The solder of the invention described here-above can be used as a replacement for Pb-containing solder in solder wave and other hand soldering processes in widespread use in the electronic and other industries.
The solder of the invention is advantageous not only from an environmental standpoint but also from the cost and availability standpoint in that the alloy compounds (Sn, Ag, Cu and P) are readily available at lower cost than the Pb-free solders including large amount of Bi, In, Zn, or Ga proposed to-date. Large volume solder applications especially will benefit from the low cost, high performance solder of the invention having the aforementioned advantages not possesses heretofore by other Pb-free solders.
The above brief description sets forth rather broadly the more important features of the present invention in order that the detailed description thereof that follows may be better understood, and in order that the present contributions to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and will form the subject matter of the claims appended hereto.
In this respect, before explaining the preferred embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood, that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for designing other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing Abstract is to enable the Intellectual Property Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms of phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. Accordingly, the Abstract is neither intended to define the invention or the application, which only is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
It is therefore an object of the present invention to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which has all of the advantages of the prior art and yet keep our environment green.
It is another object of the present invention to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which may be efficiently manufactured and marketed.
An even further object of the present invention is to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which is susceptible of a low cost of manufacture with regard to both materials and labor, and which accordingly is then susceptible of low prices of sale to the consuming public, thereby making such composition available to the buying public.
Still yet a further object of the present invention is to provide a new and improved composition of an environmental friendly Pb-free solder alloy, which can be used to make Pb-free solder bar, wire, paste, BGA ball and anode in electronics industries.
These together with still other objects of the invention, along with the various features of novelty, which characterize the invention, are pointed out with particularity in the claims forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be made to the following detailed description of the preferred embodiments of the invention.
Description of the preferred Embodiment The Pb-free solder of the present invention is based on a composition essentially of about 0.3-0.4 weight % Ag, 0.6-0.7 weight % Cu, 0.01-0.3 weight % P, 0.001-0.3 weight % Ce or La, and balance weight % Sn, with the additional of Ce or La, not exceeding 0.3 weight % of the overall composition, to enhance better micro-structural stability and to reduce grain size of the resultant solder joints.
Preferably, for electronic solder applications using the solder wave process, the melting temperature range of the solder should not exceed 10 degree Celsius. This present invention has a solder melting range of 10 degree Celsius.
A preferred Pb-free solders of the invention are listed below, exhibiting off-eutectic melting temperatures:
(1). A electrical conductor Pb-free solder composition consisting essentially of 0.3 %
weight % Ag, 0.7 weight % Cu, 0.01-0.3 weight % P, 0.001-0.3 weight % Ce or La, balance Sn and unavoidable impurities, based on the weight of composition.
The melting temperature of the solder is in the range of 217 to 227 degree Celsius.
(2). A electrical conductor Pb-free solder composition consisting essentially of 0.4 %
weight % Ag, 0.6 weight % Cu, 0.01-0.3 weight % P, 0.001-0.3 weight % Ce or La, balance Sn and unavoidable impurities, based on the weight of composition.
The melting temperature of the solder is in the range of 217 to 227 degree Celsius.
The Pb-free solder of the present invention includes at least one non-metallic component consisting essentially of P, in an amount not exceeding 0.3 weight %.
The Pb-free solder of the present invention, which comprises Sn/(0.3-0.4)Ag/(0.6-0.7)Cu/(not exceeding 0.3)P/(0.001-0.3)Ce or La, is similar as the conventional Pb-free solder comprising Sn/3.OAg/0.5Cu in welding performance, conductivity, mechanical property, pliability and so on. But since the content of Ag of the Pb-free solder of the present invention is about one-tenth of other Pb-free solder comprising Sn/3.OAg/0.5Cu (Ag is trend to react with chemical agents, such as acid or alkali and so on, thereby to produce noxious substance), so the Pb-free solder of the present invention is more safe, and has no adverse effect to living beings and environments in potential. In addition, the content of Ag [less than 0.5%] of the Pb-free solder of the present invention, which comprises Sn/(0.3-0.4)Ag/(0.6-0.7)Cu/(not exceeding 1.0)P/(0.001-0.3)Ce or La, is less than that of conventional Pb-free SnAgCu solder, so the silver compounds which are generated in the reaction between silver and halogen component of the soldering flux, are not easy to form, as a result, the phenomenon of changing to black is slight.
The method for preparing 500 Kg of the Pb-free solder of the present invention is shown below:
1. 3.5 Kg of pure copper, 250 g Ce or La and 200 Kg of pure tin are added into a steel kettle, then heated to the temperature of 400 degree Celsius, and stirred for about 45 minutes;
2. The resulting mixture is cooled to the temperature of 300 degree Celsius, then 294.5 Kg pure tin is added into the steel kettle and stirred for about 45 minutes;
3. 1.5 Kg of pure silver is added into the steel kettle, then heated to the temperature of 370 degree Celsius, and stirred for about 45 minutes;
4. 250 g P is pulverized and added into the steel kettle and stirred for about minutes at the temperature of 370 degree Celsius.
The solder of the present invention can be provided in many forms as needed for particular solder applications. The solder of the present invention can be provided as solder wire, solder bar, solder ingot, and solder powder. The solder bar and ingot can be manufactured by convention solder smelting technique. The smelting solder should be stirred 360 30 degree Celsius for 45 minutes, then let drop to 300 degree Celsius. The solder the can be chilled cast, from 300 degree Celsius to 65 10 degree Celsius, into suitable steel molds to produce bars or ingots having high purity and compositional accuracy. The solder wire can be extruded from ingot into hollow wire, which is then filled with core flux.
The above brief description sets forth rather broadly the more important features of the present invention in order that the detailed description thereof that follows may be better understood, and in order that the present contributions to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and will form the subject matter of the claims appended hereto.
In this respect, before explaining the preferred examples of the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood, that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
It is an object of the present invention to provide a Pb-free solder alloy, addition of trace amount of P (0.01-0.3 weight %) and trace amount of rare earth (Ce or La in the range 0.00 1-0.3 weight %), can improve better micro-structural stability and reduce joint oxidation rate, respectively, hence, reduce the formation of course grain solder joint.
Furthermore, the surface of soldering tin is not trend to change black, so the amount of metal oxide produced in the steel kettle of solder can be reduced, and the defective fraction rate can be reduced during electro wiring board soldering.
Example 1 The Pb-free solder of this example consists of the following components, based on the weight %: 0.3 weight % Ag, 0.7 weight % Cu, 0.05 weight % Ce or La, 0.05 weight % P, and balance Sn.
Example 2 The Pb-free solder of this example consists of the following components, based on the weight %: 0.4 weight % Ag, 0.6 weight % Cu, 0.05 weight % Ce or La, 0.05 weight % P, and balance Sn.
The raw materials, weights thereof, processing steps and processing conditions for preparing the Pb-free solder have been described in detail in foregoing paragraphs. Now, the example 1 and 2 are listed in table 1. [see table 1]
[Table 1]
Tin Silver Copper Rare earth Phosphorus Melting Sn Ag Cu Ce or La P temperature Solidus Liquidus (1) 494.50 1.5 Kg 3.5 Kg 0.25 Kg 0.25 Kg 217 227 Kg (0.3%) (0.7%) (0.05%) (0.05%) (98.95%) (2) 494.75 Kg 2.0 Kg 3.0 Kg 0.25 Kg 0.25 Kg 217 227 (98.95%) (0.4%) (0.6%) (0.05%) (0.05%) Now, the melting points of the conventional Pb-free solder (3.5 weight % Ag, 0.7 weight % Cu, and 95.8 weight % Sn) and the Pb-free solder of the example 1 and described above, and the comparisons of appearance inspection thereof are shown in table 2. [see table 2]
[Table 2] The comparisons of appearance of the Pb-free solder of the examples of the present invention and the conventional Pb-free solder comprising SnAgCu.
Metal component of Pb-free solder Melting After contacting soldering flux (weight %) temperature () comprising 0.05 % halogen for 30 min Sn Ag Cu Ce or P Solidus Liquidus Solder Joints La (1) 98.9 0.3 0.7 0.05 0.05 217 227 Not change to black (2) 98.9 0.4 0.6 0.05 0.05 217 227 Not change to black Other 95.8 3.5 0.7 NIL NIL 217 227 Change to black Pb-free solder In order to inspect the influence of soldering flux comprising halogen (0.05 %) to the Pb-free solder of the examples of the present invention and the conventional Pb-free solder comprising SnAgCu, the test is performed to inspect the appearance of soldering tin points of the Pb-free solder alloy of examples of the present invention and the conventional Pb-free solder alloy, i.e. 0.05 ml soldering flux comprising 0.05 % halogen is added to the soldering tin points, after 30 min, the appearance of soldering tin points is inspected by visual, and the results are shown in table 2. From the table 2, it is found that the soldering tin points of examples have less influence of changing to black for the soldering flux comprising halogen, when the content of Ag is small (0.3 to 0.4 weight%), and the soldering tin points change to black, when the content of Ag is up to 3.5 weight %.
[Table 3] The comparisons of oxidation resistance of the Pb-free solder of the example of the present invention and the conventional Pb-free solder comprising SnAgCu.
Initial Remainder Burning Rate of Time of Holding weight weight loss burning holding temperature (Kg) (Kg) (Kg) loss (%) temperature ( ) (hour) Example 1 100.0 99.75 0.25 0.25 10 280 Example 2 100.0 99.72 0.28 0.28 10 280 Conventional 100.0 98.00 2.00 2.00 10 280 Pb-free solder In addition, the test is performed to measure the oxidation resistance of the Pb-free solder of examples of the present invention and the conventional Pb-free solder, i.e. the solders are hold at a temperature of 280 degree Celsius for 10 hours, then measured the rate of burning loss thereof, and the results are shown in table 3.
From the test of table 3, it is found that the rates of burning loss of the Pb-free solder of examples 1 and 2, to which (0.01 to 0.3 weight %) P and (0.001-0.3 weight %) Ce or La are added, are in the range of one-sixth to one-seventh of the rate of burning loss of the conventional Pb-free solder. The results show that the oxidation resistance of the Pb-free solder alloy, to which (0.01 to 0.3 weight %) P and (0.001-0.3 weight %) Ce or La are added, is better than that of the conventional Pb-free solder having formulation of 3.5 weight % Ag, 0.7 weight % Cu, and 95.8 weight % Sn.
As such, those skilled in the art will appreciate that the conception, upon which this disclose is based, may readily be utilized as a basis for designing other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. And the abstract of the present invention is just an abstract, not intended to be limiting as to the scope of the invention in any way.
The solder of the present invention can be provided in many forms as needed for particular solder applications. The solder of the present invention can be provided as solder wire, solder bar, solder ingot, and solder powder. The solder bar and ingot can be manufactured by convention solder smelting technique. The smelting solder should be stirred 360 30 degree Celsius for 45 minutes, then let drop to 300 degree Celsius. The solder the can be chilled cast, from 300 degree Celsius to 65 10 degree Celsius, into suitable steel molds to produce bars or ingots having high purity and compositional accuracy. The solder wire can be extruded from ingot into hollow wire, which is then filled with core flux.
The above brief description sets forth rather broadly the more important features of the present invention in order that the detailed description thereof that follows may be better understood, and in order that the present contributions to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and will form the subject matter of the claims appended hereto.
In this respect, before explaining the preferred examples of the invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood, that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
It is an object of the present invention to provide a Pb-free solder alloy, addition of trace amount of P (0.01-0.3 weight %) and trace amount of rare earth (Ce or La in the range 0.00 1-0.3 weight %), can improve better micro-structural stability and reduce joint oxidation rate, respectively, hence, reduce the formation of course grain solder joint.
Furthermore, the surface of soldering tin is not trend to change black, so the amount of metal oxide produced in the steel kettle of solder can be reduced, and the defective fraction rate can be reduced during electro wiring board soldering.
Example 1 The Pb-free solder of this example consists of the following components, based on the weight %: 0.3 weight % Ag, 0.7 weight % Cu, 0.05 weight % Ce or La, 0.05 weight % P, and balance Sn.
Example 2 The Pb-free solder of this example consists of the following components, based on the weight %: 0.4 weight % Ag, 0.6 weight % Cu, 0.05 weight % Ce or La, 0.05 weight % P, and balance Sn.
The raw materials, weights thereof, processing steps and processing conditions for preparing the Pb-free solder have been described in detail in foregoing paragraphs. Now, the example 1 and 2 are listed in table 1. [see table 1]
[Table 1]
Tin Silver Copper Rare earth Phosphorus Melting Sn Ag Cu Ce or La P temperature Solidus Liquidus (1) 494.50 1.5 Kg 3.5 Kg 0.25 Kg 0.25 Kg 217 227 Kg (0.3%) (0.7%) (0.05%) (0.05%) (98.95%) (2) 494.75 Kg 2.0 Kg 3.0 Kg 0.25 Kg 0.25 Kg 217 227 (98.95%) (0.4%) (0.6%) (0.05%) (0.05%) Now, the melting points of the conventional Pb-free solder (3.5 weight % Ag, 0.7 weight % Cu, and 95.8 weight % Sn) and the Pb-free solder of the example 1 and described above, and the comparisons of appearance inspection thereof are shown in table 2. [see table 2]
[Table 2] The comparisons of appearance of the Pb-free solder of the examples of the present invention and the conventional Pb-free solder comprising SnAgCu.
Metal component of Pb-free solder Melting After contacting soldering flux (weight %) temperature () comprising 0.05 % halogen for 30 min Sn Ag Cu Ce or P Solidus Liquidus Solder Joints La (1) 98.9 0.3 0.7 0.05 0.05 217 227 Not change to black (2) 98.9 0.4 0.6 0.05 0.05 217 227 Not change to black Other 95.8 3.5 0.7 NIL NIL 217 227 Change to black Pb-free solder In order to inspect the influence of soldering flux comprising halogen (0.05 %) to the Pb-free solder of the examples of the present invention and the conventional Pb-free solder comprising SnAgCu, the test is performed to inspect the appearance of soldering tin points of the Pb-free solder alloy of examples of the present invention and the conventional Pb-free solder alloy, i.e. 0.05 ml soldering flux comprising 0.05 % halogen is added to the soldering tin points, after 30 min, the appearance of soldering tin points is inspected by visual, and the results are shown in table 2. From the table 2, it is found that the soldering tin points of examples have less influence of changing to black for the soldering flux comprising halogen, when the content of Ag is small (0.3 to 0.4 weight%), and the soldering tin points change to black, when the content of Ag is up to 3.5 weight %.
[Table 3] The comparisons of oxidation resistance of the Pb-free solder of the example of the present invention and the conventional Pb-free solder comprising SnAgCu.
Initial Remainder Burning Rate of Time of Holding weight weight loss burning holding temperature (Kg) (Kg) (Kg) loss (%) temperature ( ) (hour) Example 1 100.0 99.75 0.25 0.25 10 280 Example 2 100.0 99.72 0.28 0.28 10 280 Conventional 100.0 98.00 2.00 2.00 10 280 Pb-free solder In addition, the test is performed to measure the oxidation resistance of the Pb-free solder of examples of the present invention and the conventional Pb-free solder, i.e. the solders are hold at a temperature of 280 degree Celsius for 10 hours, then measured the rate of burning loss thereof, and the results are shown in table 3.
From the test of table 3, it is found that the rates of burning loss of the Pb-free solder of examples 1 and 2, to which (0.01 to 0.3 weight %) P and (0.001-0.3 weight %) Ce or La are added, are in the range of one-sixth to one-seventh of the rate of burning loss of the conventional Pb-free solder. The results show that the oxidation resistance of the Pb-free solder alloy, to which (0.01 to 0.3 weight %) P and (0.001-0.3 weight %) Ce or La are added, is better than that of the conventional Pb-free solder having formulation of 3.5 weight % Ag, 0.7 weight % Cu, and 95.8 weight % Sn.
As such, those skilled in the art will appreciate that the conception, upon which this disclose is based, may readily be utilized as a basis for designing other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention. And the abstract of the present invention is just an abstract, not intended to be limiting as to the scope of the invention in any way.
Claims (10)
1. A Pb-free electrical conductor solder composition consisting essentially of about 0.3-0.4 weight % Ag, 0.6-0.7 weight % Cu, 0.001-0.3 weight % Ce, and not more than 0.3 weight % P, balance Sn and unavoidable impurities, based on the weight of composition.
2. A Pb-free electrical conductor solder composition consisting essentially of about 0.3-0.4 weight % Ag, 0.6-0.7 weight % Cu, 0.001-0.3 weight % La, and not more than 0.3 weight % P, balance Sn and unavoidable impurities, based on the weight of composition.
3. The Pb-free electrical conductor solder composition of claim 1 consisting essentially of 0.3 weight % Ag, 0.7 weight % Cu, 0.00 1-0.3 weight % Ce, and 0.01 to 0.3 weight % P, balance Sn and unavoidable impurities, based on the weight of composition, with melting temperature of 217 to 227 degree Celsius.
4. The Pb-free electrical conductor solder composition of claim 1 consisting essentially of 0.3 weight % Ag, 0.7 weight % Cu, 0.00 1-0.3 weight % La, and 0.01 to 0.3 weight % P, balance Sn and unavoidable impurities, based on the weight of composition, with melting temperature of 217 to 227 degree Celsius.
5. The Pb-free electrical conductor solder composition of claim 1 consisting essentially of 0.4 weight % Ag, 0.6 weight % Cu, 0.001-0.3 weight % Ce, and 0.01 to 0.3 weight % P, balance Sn and unavoidable impurities, based on the weight of composition, with melting temperature of 217 to 227 degree Celsius.
6. The Pb-free electrical conductor solder composition of claim 1 consisting essentially of 0.4 weight % Ag, 0.6 weight % Cu, 0.001-0.3 weight % La, and 0.01 to 0.3 weight % P, balance Sn and unavoidable impurities, based on the weight of composition, with melting temperature of 217 to 227 degree Celsius.
7. The Pb-free electrical conductor solder composition of any one of claims 1 to 2, wherein the content of P is less than 0.1 weight %.
8. The Pb-free electrical conductor solder composition of any one of claims 1 to 2, wherein the content of Ce is in the range of 0.001 to 0.1 weight %.
9. The Pb-free electrical conductor solder composition of any one of claims 1 to 2, wherein the content of La is in the range of 0.001 to 0.1 weight %.
10. The Pb-free electrical conductor solder composition of any one of claims 1 to 2, wherein the content of P is in the range of 0.01 to 0.08 weight %.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2541637 CA2541637A1 (en) | 2006-03-13 | 2006-03-13 | Pb-free solder alloy compositions comprising essentially tin (sn), silver (ag), copper (cu), phosphorus (p) and rare earth: cerium (ce) or lanthanum (la) |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2541637 CA2541637A1 (en) | 2006-03-13 | 2006-03-13 | Pb-free solder alloy compositions comprising essentially tin (sn), silver (ag), copper (cu), phosphorus (p) and rare earth: cerium (ce) or lanthanum (la) |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2541637A1 true CA2541637A1 (en) | 2007-09-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2541637 Abandoned CA2541637A1 (en) | 2006-03-13 | 2006-03-13 | Pb-free solder alloy compositions comprising essentially tin (sn), silver (ag), copper (cu), phosphorus (p) and rare earth: cerium (ce) or lanthanum (la) |
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| Country | Link |
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| CA (1) | CA2541637A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102581516A (en) * | 2012-03-27 | 2012-07-18 | 郑州机械研究所 | Super-plastic copper and phosphorous welding rod and preparation method thereof |
-
2006
- 2006-03-13 CA CA 2541637 patent/CA2541637A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102581516A (en) * | 2012-03-27 | 2012-07-18 | 郑州机械研究所 | Super-plastic copper and phosphorous welding rod and preparation method thereof |
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