JP2019002066A - Lead-free tin alloy and tin plated copper wire using the same - Google Patents

Abstract

To provide a lead-free tin alloy and a tin plated copper wire using the same.SOLUTION: There are provided a lead-free tin alloy using a metal composition such as tin, copper, nickel, antimony, bismuth or the like, and a tin plated copper wire 20 using the same, and plating work can be directly done on a lead-free tin alloy in a high temperature tin tank to which a lead-free tin alloy is charged under a condition that a flux is not needed to be applied to a copper wire 21. Since the lead-free tin alloy has excellent fluidity and wettability as compared to conventional lead-free tin alloys, the thickness of a formed tin plating layer 22 is relatively uniform and copper corrosion resistance is good, the copper wire 21 is prevented from being cut in a tin impregnation process.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a lead-free tin alloy, and more particularly, to a lead-free tin alloy used for displaying a copper wire surface and a tin-plated copper wire using the same.

A tin alloy and a tin plating layer are an alloy and a display layer having good weldability and a certain antioxidant ability, and are widely applied to conductive wires, electronic parts, and printed circuit boards.
For example, a tin-plated copper wire is a product in which the surface of a copper wire (a kind of conductive wire) is covered with a single layer of tin.
The tin covering layer isolates the contact between the internal copper wire and the outside world, prevents oxidation of the copper wire, and provides better weldability in the subsequent welding process.
In the tin-plated copper wire, a commonly used manufacturing method is to perform a tin-immersion process using a tin bath containing a tin solution and to plate the tin solution on the copper wire as shown in Patent Document 1.
Moreover, after cooling, as shown in FIG. 1, the entire tin-plated copper wire 10 forms a tin-plated layer 12 on the surface of the copper wire 11, so that the surface of the copper wire is covered with a tin layer that prevents oxidation of the copper wire. .

On the other hand, the quality of the tin-plated copper wire 10 is determined by the quality of the tin-plated layer 12 such as the degree of oxidation of the tin-plated layer 12 and whether the thickness of the tin-plated layer 12 is uniform.
In the prior art, the tin plating layer 12 uses a tin-lead alloy containing tin and lead as the tin plating layer 12 on the surface of the copper wire 11.
However, lead and its compounds significantly pollute the environment.
Therefore, in recent years when environmental protection awareness is increasing, the toxicity of lead has been emphasized, and the use of tin-lead alloys containing lead tends to be restricted internationally.
Thus, the lead-free tin alloy is replaced.

However, conventional lead-free tin alloys contain various types of metals in addition to tin, directly affecting the performance and properties of the material.
In general, the conventional lead-free tin alloy having a relatively high copper content has a poor fluidity of the tin solution in the tin bath of the immersion tin process.
Therefore, the conventional lead-free tin alloy tends to remain excessively on the local surface of the copper wire 11, causing not only unevenness (thickness unevenness) on the surface of the tin plating layer 12, but an excessive amount of lead-free tin alloy is adjacent to the surface. A tin bridge phenomenon that causes a short circuit is formed between two matching tinned copper wires 10.
In order to improve the fluidity of the tin solution of the conventional lead-free tin alloy, it is necessary to further increase the temperature of the tin solution.
However, as a result, the thin copper wire 11 is exposed to a high-temperature tin bath, and the thin copper wire 11 is broken in the above-described immersion tin process due to accelerated corrosion and dissolution by the tin solution due to the high temperature in the tin solution. It may cause slenderness and even break completely.
Thus, in the subsequent welding process, a situation in which the conductive quality of the tinned copper wire 10 is poor or cannot be conducted is caused.
The phenomenon in which the copper wire is eroded and dissolved in the tin solution is called a copper erosion phenomenon or copper corrosion property, and indicates the degree of corrosion of the lead-free tin alloy tin solution on the copper wire 11.
The higher the tin solution temperature, the faster the copper wire will elute, the more serious the copper wire will become slender, the higher the probability of breakage, and the easier it will occur.

In the conventional technique, after the flux is applied to the surface of the copper wire 11, the copper wire 11 already coated with the flux is dipped in a tin bath, and the conventional lead-free tin alloy and the copper wire 11 are combined to form the surface of the copper wire 11. In some cases, the tin plating layer 12 is formed.
By using flux, it is possible to work in a relatively low temperature tin bath, but there is a problem of flux residue.
The flux remaining in the tin-plated layer 12 may cause a corrosion phenomenon in the tin-plated layer 12, which deteriorates the weldability of the tin-plated copper wire 10 in the subsequent welding process and further makes it unusable. There is also a fear.

  In the subsequent welding process, in order to avoid that the tin-plated copper wire becomes unusable, in the tin bath of the immersion tin process, in a situation where no flux is applied to the copper wire, better fluidity, better How to develop a new lead-free tin alloy with wettability, better copper corrosion resistance (higher ability to prevent copper corrosion phenomenon), and a uniform thickness tin plating layer after cooling This is an issue that has been addressed by industry and academia for a long time.

Taiwan Patent Publication No. I402375B1

  The present invention has better wettability with respect to copper wire, can increase the tin plating speed, increase the production speed by the rapid tin plating speed, increase the production amount, and reduce the copper corrosion phenomenon The present invention relates to a lead-free tin alloy that can have a good fluidity in a tin bath at the same time, thereby forming a tin plating layer having a uniform thickness on the surface of a copper wire, and avoiding a bridge phenomenon.

  The lead-free tin alloy according to the present invention comprises 3.0 to 6.0 wt% copper, 0.05 to 0.35 wt% nickel, 0.005 to 0.1 wt% antimony and 0.005 to 0.1 wt%. The other is tin.

  The lead-free tin alloy of the first type basic embodiment according to the present invention includes 3.0 to 6.0 wt% copper, 0.05 to 0.35 wt% nickel, 0.005 to 0.1 wt% antimony, 0 0.005 to 0.1 wt% bismuth, the other being tin.

  The sum of the antimony weight percentage and the bismuth weight percentage in the lead-free tin alloy is less than 0.15 wt%.

  The sum of the antimony weight percentage and the bismuth weight percentage in the lead-free tin alloy is less than or equal to 0.105 wt%.

  The sum of the antimony weight percentage and the bismuth weight percentage in the lead-free tin alloy is less than or equal to 0.1 wt%.

  The lead-free tin alloy in the lead-free tin alloy contains 4.0 to 5.0 wt% copper.

  The lead-free tin alloy in the lead-free tin alloy contains 0.15-0.25 wt% nickel.

  The lead-free tin alloy in the lead-free tin alloy contains 0.005 to 0.05 wt% antimony.

  The lead-free tin alloy in the lead-free tin alloy contains 0.005 to 0.05 wt% bismuth.

  The lead-free tin alloy includes 4.5 wt% copper, 0.2 wt% nickel, 0.05 wt% antimony and 0.05 wt% bismuth.

  The tin-plated copper wire submitted by the present invention covers the surface of the copper wire with the lead-free tin alloy to form a tin-plated layer.

The present invention is a lead-free tin alloy composed of metals such as tin, copper, nickel, antimony, bismuth and the like, and since no lead is intentionally added, toxicity is greatly reduced.
As a result, in a situation where it is not necessary to apply flux to the copper wire, the copper wire is directly immersed in a high-temperature tin bath containing the lead-free tin alloy, and a tin plating operation is performed to produce a tin-plated copper wire. it can.
Moreover, since the lead-free tin alloy of the present invention is superior in fluidity and wettability compared to the conventional lead-free tin alloy, the thickness of the formed tin plating layer is relatively uniform, and the bridge phenomenon is reduced. And having better anti-corrosiveness to copper, it is possible to prevent the copper wire from being broken in the manufacturing process.
Furthermore, the tin-plated copper wire using the lead-free tin alloy can realize not only the uniform thickness of the surface tin-plated layer but also relatively high mechanical structure strength and anti-oxidation ability.

It is a structure schematic diagram of the conventional tin plating copper wire. It is a structure schematic diagram of the tin plating copper wire of the present invention.

The present invention provides lead-free tin alloys and products using lead-free tin alloys.
The lead-free tin alloy is substantially free of lead (Pb).
The phrase “substantially free of lead” means that in principle, no lead is intentionally added to the tin alloy.
For example, inevitable impurities or contact that are not intentional in the manufacturing process can be regarded as substantially free of lead or lead-free based on the gist of the present invention.
Moreover, since lead is often present in tin (Sn) or other metals in an impure state, a very small amount of similar impurities is very difficult to remove completely with common metallurgical techniques. .
The upper limits for lead contamination in various lead-free alloys are still undefined, but are defined as follows in the definitions of important association organizations in Japan, the US and Europe.
EU RoHS lwt% Pb
US JEDEC 0.2wt% Pb
0 of Japan JEIDA. lwt% Pb
Of these, wt% refers to weight percent, and wt% below in the text similarly refers to weight percent.

The lead-free tin alloy of the present invention is composed of a metal such as tin, copper (Cu), nickel (Ni), antimony (Sb), bismuth (Bi).
Lead-free tin alloy consists of 3.0-6.0 wt% copper, 0.05-0.35 wt% nickel, 0.005-0.1 wt% antimony, 0.005-0.1 wt% bismuth. Including others is tin.
The sum of the antimony weight percentage and the bismuth weight percentage is less than 0.15 wt%.

To avoid misunderstandings, the expression “others are tin” will be explained.
The above terms should not be understood to exclude insignificant but inevitable miscellaneous in other manufacturing processes.
Thus, “other than tin” is understood to be composed of tin plus inevitable impurities to supplement lead-free tin alloys up to 100 wt% weight percent, if any are present. It should be.
Further, the limitation of the numerical range in the present invention and the claims always includes the end value.

(Example)
Production of a lead-free tin alloy according to the invention:
The lead-free tin alloy according to the present invention is
Manufactured by a method including the following steps.
(1) Prepare a corresponding metal material based on the corresponding metal component and weight percent.
(2) The prepared material is heated and melted and cast to form a lead-free tin alloy.
The lead-free tin alloy according to the present invention can be manufactured using the manufacturing method disclosed in Patent Document 1.

Operation of a lead-free tin alloy according to the present invention:
The operation of the lead-free tin alloy according to the present invention is shown in FIG.
A lead-free tin alloy according to the present invention is bonded to form a tinned copper wire 20.
The tin-plated copper wire 20 covers the surface of the copper wire 21 with a lead-free tin alloy to form a tin-plated layer 22.
Since the lead-free tin alloy has better wettability with respect to the copper wire 21 in the tin bath (not shown), the speed of tin plating is increased and the speed of tin plating is increased. Speed can be increased, production can be increased, and copper corrosion can be reduced.
At the same time, the lead-free tin alloy according to the present invention has good fluidity in the tin bath, can form the tin plating layer 22 with a uniform thickness on the surface of the copper wire 21, and can avoid the bridge phenomenon.
The composition of the tin plating layer 22 and the lead-free tin alloy are homologous.

Effect evaluation and test of lead-free tin alloy according to the present invention:
Lead-free tin alloys are evaluated for copper corrosion by an anti-copper corrosion test.
The lead-free tin alloy is tested for tin plating rate by a wetness test.
The lead-free tin alloy is tested for fluidity by a fluidity test.

Anti-copper corrosion test:
A copper wire having a wire diameter of 0.1 mm is immersed in the lead-free tin alloy of the example or the comparative example, and the test is performed in a tin solution at 480 ° C.
Connect the copper wire to the circuit and measure the time taken for the copper wire to be completely melted and cut.
If it exceeds 2.5 seconds before cutting, it is determined that the copper corrosion resistance is good, and “◯” is displayed.
If it is between 2.0 and 2.5 seconds, it is determined that the copper corrosion resistance is possible, and “Δ” is displayed.
If it is 2.0 seconds or less, it is determined that anti-corrosion corrosion has failed, and “X” is displayed.

Fluidity test:
In this experiment, an iron frame was specially manufactured, a copper wire having a wire diameter of 0.1 mm was wound on the copper wire with an interval distance of 0.2 mm, and the copper wire interval distance between two adjacent copper wires was 20 pieces. Form.
After winding a copper wire and immersing an iron frame having a distance of 20 copper wires in a tin solution at 480 ° C. formed with the lead-free tin alloy of Example or Comparative Example for 1 second, Remove from the tin solution and place to cool.
This is magnified with an optical microscope, and whether or not a tin bridge has appeared between two adjacent copper wires, and if so, the quantity of the tin bridge is observed.
If a tin bridge smaller than or equal to one is formed between two adjacent copper wires, it is determined that the fluidity is good, and “◯” is displayed.
If there are 2 to 4 tin bridges, it is determined that fluidity is possible, and “Δ” is displayed.
If the number of tin bridges is greater than or equal to 5, it is determined that the fluidity has failed, and “X” is displayed.

Moisture test:
A copper piece having a thickness of 0.3 mm, a width of 10 mm and a length of 30 mm is used.
After the copper piece is eroded, a wetness test is performed by a wetting balance method in a tin solution at 380 ° C. formed with the lead-free tin alloy of Example or Comparative Example.
This test, a standard the Junshime time t _0.
The moistening time t ₀ is the time taken for the tin solution to form a moisture angle of 90 degrees with respect to the copper piece after the copper piece contacts the tin solution and breaks through the surface of the tin solution. Point to.
If the moistening time t ₀ is shorter than 1.5 seconds, it is determined that the moisturizing property is good, and “◯” is displayed.
If Junshime time _{t 0} is 1.5 to 2.0 seconds, it is determined that the Jun wet Allowed, displays "△".
If the moistening time t ₀ exceeds 2 seconds, it is determined that the moisturizing has failed and “X” is displayed.

Based on the manufacturing method of the lead-free tin alloy by this invention, the lead-free tin alloy of each alloy composition described in the following Table 1 is prepared.
Table 1 includes the lead-free tin alloys of Examples 1 to 14 according to the present invention, and Comparative Examples 1 to 8 for comparison with Examples.
Moreover, an anti-corrosion test, a fluidity test, and a moisture test were performed on Examples 1 to 14 and Comparative Examples 1 to 8, respectively, by the effect evaluation and test of the lead-free tin alloy according to the present invention.

The meaning of “remaining amount” displayed for Sn in Table 1 is “other than tin”.
Thus, the meaning of the term “other than tin” or “remaining amount” should be understood to be supplemented until the lead-free tin alloy is at a weight percent of 100 wt%.
In the same example or the same comparative example, three tests of an anti-copper corrosion test, a fluidity test, and a moisture test were conducted, and if one “X” appeared in the test result, the “total evaluation result” in Table 1 "X" is displayed in the "" column, and the examples or comparative examples do not meet the requirements of the present invention.
If one arbitrary “Δ” appears in the test result, “Δ” is displayed in the “overall evaluation result” column in Table 1, and the example or comparative example is said to meet the requirements of the present invention. That is.
If “○” appears in all three test results, “○” is displayed in the “Overall Evaluation Result” column in Table 1, and the examples not only meet the requirements of the present invention but also the best performance. It is an example.

In Table 1, since “◯” is displayed in the “overall evaluation result” column of Example 1, Example 1 is the best example.
The lead-free tin alloy contains 4.5 wt% copper, 0.2 wt% nickel, 0.05 wt% antimony, 0.05 wt% bismuth, the others are tin, and the antimony weight percentage (this implementation) The total of the example is 0.05 wt%) and the weight percentage of bismuth (this example is 0.05 wt%) is less than 0.15 wt% (this example is equal to 0.1 wt%).

In the process of the invention concept, a single metal cannot predict the characteristics exhibited in the entire alloy, and needs to be evaluated and known in the complicated manufacturing process (manufacturing process and preparation process) of the alloy. .
Moreover, by constantly and gradually changing the metals or components having similar properties, the ones having the necessary characteristics are searched for, and thus the properties of each metal or component are superior to those of the lead-free tin alloy composition. It is finally determined whether or not copper corrosion resistance, fluidity and wettability can be provided.
Therefore, Examples and Comparative Examples in Table 1 will be described as follows.

3.0-6.0 wt% copper:
The weight percentage of copper added to the lead-free tin alloy affects the superiority or inferiority of the anti-copper corrosion test.
If the weight percentage of copper is too low, the lead-free tin alloy cannot pass the anti-corrosion test.
If the copper weight percentage is too high, favorable anti-corrosion properties can be achieved, but the lead-free tin alloy cannot pass the flowability test and the wetness test.
Comparative Example 7 employs 2.0 wt% copper, which is labeled “X” in the anti-copper corrosion test, indicating that if the copper weight percentage is too low, the alloy cannot pass anti-corrosion. Yes.
Comparative Example 8 employs 7.0 wt% copper, which is indicated as “◯” in the anti-copper corrosion test, but in the flowability test, the moisture test, and the “overall evaluation result” column, “X”. If the copper weight percentage is too high, it indicates that the alloy cannot pass the flowability test and the wetness test.
Example 12 employs 3.0 wt% copper, Example 11 employs 4.0 wt% copper, Examples 1 to 10 employ 4.5 wt% copper, and Example 13 Employs 5.0 wt% copper, and Example 14 employs 6.0 wt% copper, but “△” or “◯” is displayed in the “overall evaluation result” column in Table 1. This indicates that inclusion of 3.0 to 6.0 wt% copper in the lead-free tin alloy can meet the requirements of the present invention.
In particular, when comparing Example 12 in which the copper content is increased to 3.0 wt% compared to Comparative Example 7 employing 2.0 wt% copper, the lead-free tin alloy of Example 12 meets the requirements of the present invention. doing.
Comparing Example 14 in which the copper content is reduced to 6.0 wt% compared to Comparative Example 8 employing 7.0 wt% copper, the lead-free tin alloy of Example 14 meets the requirements of the present invention. ing.

  As described above, it can be seen that the lead-free tin alloy according to the present invention is most excellent when it contains 4.0 to 5.0 wt% of copper.

0.05-0.35 wt% nickel:
Increasing the weight percentage of nickel added to the lead-free tin alloy provides favorable anti-corrosion properties, but may lead to the risk that the lead-free tin alloy will not pass the fluidity test and the moisture test.
Comparative Example 5 employs 0.01 wt% nickel and is labeled “X” in the anti-copper corrosion test, indicating that the alloy cannot pass anti-corrosion due to the nickel having an excessively low weight percentage. Yes.
Comparative Example 6 employs 0.4 wt% nickel, and “O” is displayed in the anti-copper corrosion test, but “X” is displayed in the fluidity test, the moisture test, and the “overall evaluation result” column. In other words, nickel alloys with excessively high weight percentages have failed to pass the fluidity test and the wetness test.
Example 8 employs 0.05 wt% nickel, Example 7 employs 0.15 wt% nickel, Example 9 employs 0.25 wt% nickel, and Examples 1 to 6 and Example 11 to Example 14 employ 0.2 wt% nickel, Example 10 employs 0.35 wt% nickel, and “△” or “◯” is displayed in the “Overall Evaluation Result” column in Table 1. This indicates that inclusion of 0.05 to 0.35 wt% nickel in the lead-free tin alloy can meet the requirements of the present invention.
Comparing Example 8 in which the nickel content is increased to 0.05 wt% compared to Comparative Example 5 employing 0.01 wt% nickel, the lead-free tin alloy of Example 8 meets the requirements of the present invention. ing.
Comparing Example 10 in which the nickel content was reduced to 0.35 wt% compared to Comparative Example 6 employing 0.4 wt% nickel, the lead-free tin alloy of Example 10 met the requirements of the present invention. ing.

  As described above, the lead-free tin alloy according to the present invention is best when it contains 0.15 to 0.25 wt% nickel.

It has already been found that the lead-free tin alloy according to the present invention cannot meet the requirements of the present invention unless 3.0 to 6.0 wt% copper and 0.05 to 0.35 wt% nickel are employed.
That is, the lead-free tin alloy according to the present invention is best when it contains 4.0 to 5.0 wt% copper and 0.15 to 0.25 wt% nickel.
Since the weight percentages of copper and nickel employed in Comparative Examples 5 to 8 do not already meet the above-mentioned conditions, all the examples in Table 1 and Comparative Examples 1 to 4 will be discussed below.

  The sum of the antimony weight percentage and the bismuth weight percentage is less than 0.15 wt%.

Increasing the weight percentage of antimony and bismuth added to the lead-free tin alloy can achieve good fluidity and moisture, but there is a risk that the lead-free tin alloy will not pass the anti-corrosion test.
The total of the antimony weight percentage value and the bismuth weight percentage value employed in Comparative Examples 1 to 3 is equal to 0.15 wt%.
The total of the antimony weight percent value and the bismuth weight percent value employed in Comparative Example 4 is equal to 0.2 wt%.
Comparative Examples 1 to 4 are all labeled as “X” in the anti-corrosion test, and have not passed the anti-corrosion test, but have good fluidity and moisture.
The antimony and bismuth employed in Example 6 were both 0.01 wt%, the antimony and bismuth employed in Examples 4 and 5 were both 0.055 wt%, and the antimony and bismuth employed in Examples 2 and 3 were used. Both bismuth was 0.105 wt%, and both antimony and bismuth employed in Examples 7 to 14 and Example 1 were 0.1 wt%. In Table 1, “△” or “ "○" is displayed, and if the total of the antimony weight percentage value and the bismuth weight percentage value contained in the lead-free tin alloy is less than 0.15 wt%, the requirement of the present invention can be met. Show.
In particular, in comparison with Comparative Example 1 in which both 0.15 wt% antimony and bismuth are employed, the combined content of antimony and bismuth is reduced to 0.15 wt% or less. When the numerical value is 0.1 wt%), the lead-free tin alloy of Example 1 meets the requirements of the present invention.

  The total amount of antimony weight percent and bismuth weight percent employed by the lead-free tin alloy according to the present invention is most preferred when it is less than or equal to 0.105 wt%.

  The lead-free tin alloy according to the present invention is more preferred when the sum of the antimony weight percentage value and the bismuth weight percentage value is less than or equal to 0.1 wt%.

0.005 to 0.1 wt% antimony:
Increasing the weight percentage of antimony added to the lead-free tin alloy can achieve favorable fluidity, but there is a risk that the anti-corrosion resistance will be reduced.
In Examples 2, 5, and 6, the weight percentages of copper, nickel, and bismuth are all homologous, and the weight percentage of antimony is 0.005 wt% in Example 6, 0.05 wt% in Example 5, respectively. Increase to 0.1 wt% of Example 2.
Care must be taken in the following.
The fluidity test results were raised from the acceptance of Example 6 (indicated as “Δ”) to the favorable results in Example 5 and Example 2 (indicated as “◯”). Is just the opposite of the results of the fluidity test.
The anti-corrosion test result is lowered from the favorable example 6 (indicated as “◯”) to the acceptable state in example 2 (indicated as “Δ”).
In Examples 2, 5, 6, and 1, “△” or “◯” is displayed in the “overall evaluation result” column in Table 1, and 0.005 to 0.1 wt% of antimony in the lead-free tin alloy It is shown that the requirement of the present invention can be met.

  The lead-free tin alloy according to the present invention is better when it contains 0.005 to 0.05 wt% antimony.

0.005-0.1 wt% bismuth:
When the weight percentage of bismuth added to the lead-free tin alloy is increased, a preferable moisture can be achieved, but there is a risk that the anti-corrosion property is deteriorated.
The weight percentages of copper, nickel and antimony in Examples 3, 4, and 6 are all similar, but the weight percentage of bismuth is 0.005 wt% of Example 6 and 0.05 wt% of Example 4, respectively. In Example 3, it is raised to 0.1 wt%.
Care must be taken in the following.
The wettability test result is raised from acceptable in Example 6 (indicated as “Δ”) to good in Example 3 (indicated as “◯”), but the anti-corrosion test result is wet. This is just the opposite of the sex test results.
The anti-corrosion test result has decreased from good (displayed as “◯”) in Example 6 to acceptable (displayed as “Δ”) in Example 3.
In Table 1, Examples 3, 4, 6, and 1, “△” or “◯” is displayed in the “overall evaluation result” column, and 0.005 to 0.1 wt% of bismuth in the lead-free tin alloy. Including this indicates that the requirement of the present invention can be met.

  The lead-free tin alloy according to the present invention is better when it contains 0.005 to 0.05 wt% bismuth.

The lead-free tin alloy of the present invention can be used for joining a copper wire and an object to be joined (for example, another metal wire) as a joining material in addition to being used for a tin-plated copper wire.
In the joining process, the copper wire and the object to be joined are preliminarily bonded by a physical method, and then the copper wire and the object to be joined are immersed together in a tin bath. Between the copper wire and the object to be joined, The lead-free tin alloy of the present invention is bonded by a bonding site formed.
In the present invention, the copper corrosion phenomenon can be mitigated and the fluidity of the tin solution can be improved, so that the copper corrosion phenomenon at the joining site can be reduced, the appearance of the joining site can be improved, and the bridging phenomenon at the joining site can be reduced. .

Compared with the prior art, the present invention is a lead-free tin alloy composed of metals such as tin, copper, nickel, antimony, bismuth and the like, and since lead is not intentionally added, toxicity is greatly reduced.
As a result, it is possible to manufacture a tin-plated copper wire by directly immersing the copper wire in a high-temperature tin bath containing a lead-free tin alloy and performing a tin-plating operation in a situation where it is not necessary to apply a flux to the copper wire. .
Moreover, since the lead-free tin alloy of the present invention is superior in fluidity and wettability compared to the conventional lead-free tin alloy, the thickness of the formed tin plating layer is relatively uniform, and the bridge phenomenon is reduced. And having better anti-corrosiveness to copper, it is possible to prevent the copper wire from being broken in the manufacturing process.
A tin-plated copper wire using a lead-free tin alloy has not only a uniform surface tin-plated layer thickness, but also can achieve relatively reliable mechanical structure strength and antioxidant capacity.

  The present invention has novelty that is a requirement for patent registration, has sufficient progress compared to conventional similar products, has high practicality, meets social needs, and has very high industrial utility value .

DESCRIPTION OF SYMBOLS 10 Tin plating copper wire 11 Copper wire 12 Tin plating layer 20 Tin plating copper wire 21 Copper wire 22 Tin plating layer

Claims (10)

  Lead-free tin alloy consists of 3.0-6.0 wt% copper, 0.05-0.35 wt% nickel, 0.005-0.1 wt% antimony and 0.005-0.1 wt% bismuth. A lead-free tin alloy characterized in that the other is tin.   2. The lead-free tin alloy according to claim 1, wherein the total sum of the antimony weight percentage and the bismuth weight percentage is less than 0.15 wt%.   3. The lead-free tin alloy according to claim 2, wherein the total sum of the antimony weight percent value and the bismuth weight percent value is less than or equal to 0.1 wt%.   The lead-free tin alloy according to claim 1, wherein the lead-free tin alloy contains 4.0 to 5.0 wt% copper.   The lead-free tin alloy according to claim 4, wherein the lead-free tin alloy contains 0.15 to 0.25 wt% of nickel.   The lead-free tin alloy according to claim 5, wherein the lead-free tin alloy contains 0.005 to 0.05 wt% of antimony.   The lead-free tin alloy according to claim 6, wherein the lead-free tin alloy contains 0.005 to 0.05 wt% of bismuth.   The lead-free tin alloy according to claim 7, wherein the sum of the antimony weight percent value and the bismuth weight percent value is less than or equal to 0.1 wt%.   The lead-free tin alloy according to claim 8, wherein the lead-free tin alloy includes 4.5 wt% copper, 0.2 wt% nickel, 0.05 wt% antimony, and 0.05 wt% bismuth. alloy.   The said tin plating copper wire coat | covers the surface of a copper wire with the lead-free tin alloy of Claim 1, and forms a tin plating layer, The tin plating copper wire characterized by the above-mentioned.