JP2008023591A - PROCESS FOR PRODUCING SnZn SOLDER MATERIAL - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for producing an SnZnAlSi solder by adding an AlSi mother alloy satisfying predetermined requirements into molten ZnSn. <P>SOLUTION: This process for producing an SnZnAlSi solder comprises a first step of previously preparing an AlSi mother alloy having a liquidus line temperature of 850°C or below and having an Si content of 0.5 to 30% by allowing Al and Si to simultaneously react in an atmosphere of 680 to 1,200°C and if needed, optionally previously preparing a CuSi mother alloy having an Si content of 0.5 to 35%, a second step of making an SnZn alloy having a Zn content of 3 to 50% a molten state, a third step of charging an AlSi mother alloy into a molten SnZn alloy to diffuse and homogeneously disperse Al and Si into the SnZn alloy, and a fourth step of cooling and solidifying an SnZn alloy having an oxygen content of 5 to 50 ppm, an Al content of 3 to 15 ppm, an Si content of 3 to 70 ppm, and an (Al+Si) content of 5 to 80 ppm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a method for producing Pb-less solder used for joining joints of electrical equipment, mechanical parts, decorative parts, and the like, and more particularly to a method for producing SnZnAlSi solder having a low rate of reduction in joint strength.

    Conventional soldering generally uses SnPb solder alloys (JIS, Z, 3282) from the viewpoint of melting temperature and wettability. The SnPb eutectic solder alloy has a feature that its eutectic temperature is 183 ° C., which is much lower than the melting point of the object to be joined, and that it is lower than the temperature at which many thermosetting resins start to gasify. Have.

    By the way, (A) the wettability with a to-be-joined member is good for a solder alloy. (B) It should be possible to perform a joining operation at a temperature that does not cause thermal damage to the members to be joined. (C) Do not generate extremely fragile compounds with the members to be joined. (D) The printing workability is good. (E) It is required that the rate of decrease in bonding strength after a long-time standing test under conditions of a temperature of 85 ° C. and a humidity of 85% is low.

The conventional SnPb-based solder alloy described above satisfies the requirements (A), (B), (C), (D), and (E). However, since Pb, which is toxic to recent environmental problems, is included, an environment-friendly Pb-free solder material is required, and recently SnZ-based solder has been proposed as a promising one.
SnZn solder has a melting temperature of 199 ° C. and has an advantage similar to that of a conventional SnPb eutectic solder. However, SnZn solder is preferentially oxidized with Zn that is highly oxidizable, and there is a problem in that a Zn oxide film is formed on the surface of the solder and the wettability between the solder and the bonded portion is hindered. Therefore, as a technique for suppressing the formation of Zn oxide in the surface layer, a technique for adding Al that is oxidized more preferentially than Zn is disclosed in the following patent document. Addition of Al is effective for the purpose of suppressing Zn oxide, but on the other hand, formation of a coarse structure mainly composed of Al oxide is observed in a part of SnZn after soldering. In addition, a problem has been pointed out that the bonding strength is reduced and the range of variation is increased.

    Japanese Patent Application No. 10-184806 discloses one additive component selected from the group consisting of Sn, Zn in a proportion of 3 to 21 wt% with respect to Sn, and Y, Al, Si. % Pb-free solder material is proposed.     Japanese Patent Application No. 11-092033 discloses Pb containing Zn and Sn as main components and an additive selected from Mg, Mn, Al, Si, Fe, Ge, C, N, B, H and ammonia. There has been proposed a method for forming a lead-free joining member, which includes a step of heating free solder to form a molten metal and a step of forming a solder layer on a metal surface.     Japanese Patent Application No. 2002-242812 discloses a Pb-free solder containing Sn as a main component and comprising 6 to 10% Zn, 0.0015 to 0.03% Mg, and 0.0010 to 0.006% Al. Materials have been proposed.     Japanese Patent Application No. 2002-537923 proposes a Pb-free solder material mainly composed of Sn and made of 3 to 14% Zn and 0.0020 to 0.0080% Al.

Problems to be solved by the invention

    However, the above-described conventional Pb-free solder and the method for forming the conventional Pb-free solder have taken into consideration the environmental problems, but have the following problems and are desired to be improved.

(1) In the Pb-free solder material described in Japanese Patent Application No. 10-184806, one type of Y, Al, and Si is added to 0.5% or less as an additive component that suppresses the temporal change of the SnZn solder material. A solder alloy is suggested. Although these additive components suppress the formation of Zn oxide and improve the wettability to some extent, the wettability varies. In addition, a method for producing a SnZn solder material that suppresses variations is not disclosed.
In other words, although it shows a certain degree of suppression effect on the Zn oxide generation problem of the outermost surface layer of SnZn solder, the auxiliary components such as Al and Si are simply present in SnZn, so that the wettability of It is not possible to solve variations and bonding strength variations. As a result of research, it has been found that a production method in which an AlSi master alloy having a predetermined ratio is added to molten SnZn in advance is effective.
(2) In the method for forming a lead-free joining member described in Japanese Patent Application No. 11-092033, a solder alloy obtained by adding an additive such as Al or Si to SnZn is heated, The process to do is shown. Although this technique also improves the wettability to some extent, as described above, it cannot solve the problems of the wettability variation and the bonding strength variation. Thus, although it has shown about the point provided with the process of heating and making a molten metal, and the process of forming this solder layer on a metal surface, there is no suggestion about the manufacturing method which manufactures solder alloy itself optimally.
(3) The Pb-free solder material described in Japanese Patent Application No. 2002-242812 is a solder alloy in which a predetermined amount of Mg and Al are simultaneously added to SnZn. Addition of Mg and Al prevents the formation of Zn oxide preferentially, and solves the wettability and the preservability of solder, but the wettability varies and the joint strength There is variation in the rate of decline. That is, it is suggested that sufficient SnZn solder cannot be obtained only by compositional improvement of adding Mg and Al to SnZn.
(4) The Pb-free solder material described in Japanese Patent Application No. 2002-537933 has the same effect of suppressing the generation of Zn oxide and improving wettability by the effect of a small amount of Al in SnZn. However, some of the generated Al oxides have diameters or widths exceeding 5 μm, and the degree of dispersion is not uniform.

    SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a SnZn-based solder material having a low rate of decrease in bonding strength in SnZn solder in consideration of environmental problems. In the production of SnZn solder, the present invention has developed a method for producing SnZnAlSi solder material using an AlSi master alloy under predetermined conditions, and has achieved the object by reducing the variation in the rate of decrease in bonding strength.

    That is, the production method of the present invention is to solidify at a predetermined cooling rate and to produce an AlSi master alloy having a predetermined liquidus temperature in order to improve the reduction rate of the SnZn alloy bonding strength. Is added as an additive component to the SnZn molten metal to optimize the (Al + Si) amount, (Si / Al) ratio and oxygen amount, and to provide a manufacturing method for manufacturing a SnZnAlSi solder having an oxygen amount of 30 ppm or less. Here, the predetermined cooling rate is a cooling rate until the molten AlSi alloy cools to room temperature. As a result, a manufacturing method for producing SnZnAlSi solder with improved wettability and improved joint strength reduction rate is obtained.

Means and actions to solve the problem

    The present inventors have completed a method for manufacturing a solder material that solves the problem of the rate of decrease in the bonding strength of (E) after using a solder material that does not contain Pb (lead).

    Here, the preferable state of the method for manufacturing a solder material according to the present invention is to provide a manufacturing method for improving the problem of decrease in bonding strength in (E). The patent document discloses a SnZn alloy to which Al, Si, and Mg are added as auxiliary components. However, this is not sufficient for obtaining a SnZn solder with an improved reduction rate of bonding strength, and optimization of its manufacturing conditions is important, such as using an AlSi mother alloy prepared separately under predetermined conditions as an additive component.

That is, the present invention is a manufacturing method characterized by using the AlSi mother alloy of the above-mentioned predetermined condition as an additive in a SnZn alloy in a molten state, wherein the oxygen amount is 5 to 50 ppm and the Al amount is 3 to 20 ppm. The present invention provides a manufacturing method for manufacturing a SnZnAlSi solder having a low bonding strength reduction rate in which only 5 to 30 ppm of Si is left.
Here, Al suppresses the formation of Zn oxide by selective oxidation of Zn in SnZn. Moreover, Si exhibits an effect that is more effective than Al in limiting the elution of Zn to the surface. If the amount of oxygen exceeds, for example, 50 ppm, blowhole formation is observed, so that a predetermined amount of Al and Si is required to suppress blowhole formation. When the amount of oxygen is small, the amounts of Al and Si are small.

As a first point, the present invention relates to a manufacturing method for manufacturing SnZnAlSi solder by adding an AlSi mother alloy separately prepared under predetermined conditions to SnZn being melted.
The second point is characterized by having a preferable liquidus temperature of 850 ° C. or lower. The present invention relates to a manufacturing method for manufacturing SnZnAlSi solder by adding an AlSi mother alloy.
A third point is that the amount of Si is in the range of 0.5 to 5 times the amount of Al.

First Embodiment of the Present Invention: The present invention is a method for producing a SnZnAlSi solder, characterized in that all of the first to fourth steps are sequentially performed.
A first step of preparing an AlSi master alloy containing 0.5 to 45% by weight of Si and the balance being Al (preparing a CuSi alloy to be used in combination with the AlSi master alloy if necessary) First step , Zn content is 3 to 50 wt. second step of the SnZn alloy melt is%, diffuse the AlSi base alloy, a third step of introducing into the SnZn alloy with a CuSi alloy to the molten state if necessary, Al and Si in the SnZn alloy Each of the fourth steps for producing a SnZn alloy in which only 3 to 50 ppm of oxygen, 3 to 20 ppm of Al, and 5 to 30 ppm of Si remain in the SnZn alloy after being dispersed and cooled and solidified. This is a method for producing a SnZnAlSi solder having a low rate of decrease in bonding strength, characterized in that the steps are sequentially provided.

    That is, in the third step, not only Al alone is added to the SnZn after cooling and solidification, but only Si is not added alone, but a master alloy made of both AlSi prepared in advance (CuSi alloy is also used if necessary) ) Is simultaneously added. A method for producing a SnZnAlSi alloy. In the AlSi master alloy, an AlSi master alloy containing 0.5 to 30%, preferably 0.5 to 20% of Si is used.

Compared to the melting temperature of Al of 660 ° C. and the melting temperature of Si of 1440 ° C., the AlSi master alloy having a composition range used in the production method of the present invention is sufficiently low because it uses an eutectic of Al and Si. It has a melting temperature (solidus temperature) of 577 ° C. Therefore, the viscosity becomes lower, and when the AlSi master alloy having the above composition range is added to the SnZn molten metal, there is an advantage that it diffuses at a high speed. This is extremely useful for a method of manufacturing a SnZn solder having a fine and uniform structure.
On the other hand, when the additive component is pear, in the case of only Al, in the case of only Si, when “Table 1” (Reference Examples 1 to 3) is used, a high melting point undissolved phase exists in SnZn. This is not preferred as a method for producing SnZn solder.
Moreover, when an AlMg alloy is manufactured with Al and Mg and this is put into a molten SnZn alloy, a plurality of AlMg intermetallic compounds are produced in the SnZn alloy. The presence of this AlMg intermetallic compound impairs the homogeneity of the structure of the solder alloy and is particularly undesirable because it causes variations in bonding strength, so the use of an AlMg alloy is excluded. The AlMg alloy has a clear difference as compared with the production method of the present invention using an AlSi master alloy, and is negative.

    In the first step, in the AlSi master alloy having an Si content of less than 0.5%, Si is segregated and distributed in the AlSi master alloy because of the small amount, which is not preferable as the master alloy. In order to alleviate this disadvantage, the lower limit of the amount of Si in the AlSi mother alloy is 0.5% or more (here, the Si amount is Si in the AlSi mother alloy prepared in advance, and SnZn solder) It is not the amount of Si in the inside). Moreover, the advantageous characteristic of AlSi having a solidus temperature of 557 ° C. cannot be fully utilized. When an AlSi master alloy having an Si content exceeding 45% is used, the liquidus temperature of the AlSi master alloy exceeds 1,000 ° C. When added to the SnZn molten metal, mainly Si particles, other Si oxides, Al The oxide often remains as an unmelted phase, impairs the uniformity of the structure of the SnZnAlSi alloy and contributes to variations in bonding strength, which is not preferable as a method for producing SnZn solder. If the amount of Si is about 30%, the liquidus temperature of the AlSi mother alloy is further reduced to 800 ° C., and when added to the SnZn molten metal, the unmelted phase is further reduced, which is preferable. Therefore, the amount of Si is 45% or less, preferably 30% or less. From the above, the amount of Si in the AlSi master alloy is 0.5 to 45%.

When an AlSi master alloy is added to a SnZn solder alloy molten metal having a Zn content of less than 3% , the liquidus temperature rises and the viscosity (fluidity) of the solder material during work decreases. When used as a solder for joining with Cu, generation of a CuSn compound proceeds.
When an AlSi master alloy is added to a SnZn alloy molten metal with a Zn content exceeding 50 %, it is necessary to consider the temperature effect on the bonded part due to an increase in soldering operation temperature due to an increase in liquidus temperature. . Further, an increase in Zn, which is an element having a significantly higher vapor pressure than Sn, causes a problem in terms of composition management due to a large compositional variation in the SnZn alloy during the melting work for manufacturing the alloy and after soldering.
Therefore, the manufacturing method of the present invention is based on the third step of adding the AlSi master alloy having the predetermined condition to the SnZn alloy in a molten state containing 3 to 50% Zn. In particular, when the step of adding the AlSi master alloy to the production of the SnZn alloy having the Zn content of about 9 % (third step) is applied, the SnZnAlSi solder having a lower bonding temperature is obtained. This is useful as a manufacturing method.

    In addition, if the amount of Si in the SnZnAlSi solder is only an AlSi master alloy, and if the amount of Si necessary to exert the effect is insufficient, a CuSi alloy is used in combination with the AlSi master alloy, and To do.

    In the first step, a predetermined amount of Al and Si are allowed to act simultaneously in an atmosphere maintained at a temperature of 680 ° C. or higher and 1200 ° C. or lower, whereby a liquid having a temperature of 1,000 ° C. or lower, preferably 850 ° C. or lower. 2. The method for producing a SnZnAlSi solder having a low bonding strength reduction rate according to claim 1, wherein an AlSi master alloy having a phase line temperature is prepared.

That is, the present invention is to produce an SnZnAlSi solder by adding an AlSi master alloy characterized by having a preferable liquidus temperature.
In the production of SnZnAlSi solder, the preferred liquidus temperature of the AlSi master alloy used is 1,000 ° C. or less. When an AlSi master alloy having a liquidus temperature exceeding 1,000 ° C. is used as an additive, the Al and Si in the SnZnAlSi solder after being put into SnZn and cooled and solidified is segregated, resulting in a decrease in wettability. In addition, an increase in the bonding strength variation width is observed, and this is not preferable as a method for producing SnZnAlSi solder with a low decrease rate of the bonding strength.

(A): When the predetermined amount of Al and Si is allowed to act in a temperature atmosphere controlled to a temperature lower than 680 ° C., the Al and Si in the resulting AlSi master alloy have a microscopically inhomogeneous composition distribution. Even if a method of manufacturing SnZnAlSi solder by introducing such an inhomogeneous distribution AlSi master alloy into SnZn, a SnZnAlSi solder having a large reduction rate of bonding strength and a large variation is obtained, which is a preferable manufacturing method. Absent.
(B) When the predetermined amount of Al and Si is allowed to act in a temperature atmosphere controlled at a temperature higher than 1200 ° C., Al and Si in the resulting AlSi master alloy have a higher melting point. When the molten phase is formed in a large amount and the AlSi master alloy in such a state is added (added) to SnZn, the bonding strength is also lowered due to the decrease in wettability. It becomes a SnZnAlSi solder having a low bonding strength reduction rate and a large variation, and is not preferable as a manufacturing method for manufacturing a SnZnAlSi solder having a low bonding strength reduction rate.
(C): The AlSi master alloy to be used in the production method of the present invention as described above is obtained by causing the predetermined amount of Al and Si to act simultaneously in a temperature atmosphere controlled in a temperature range of 680 ° C. or more and 1200 ° C. or less, The object is to prepare an AlSi master alloy having a liquidus temperature of 1,000 ° C. or less, preferably 850 ° C. or less and comprising 0.5 to 30% by weight of Si and the balance Al. As a result, an AlSi master alloy useful for producing a SnZnAlSi solder with a low reduction rate of bonding strength is obtained.

(A): In the case where only the component of the additive added to the molten SnZn is Al, in “Table 1” (Reference Example 2), when charged into the molten SnZn, Al does not diffuse quickly into the molten SnZn. As a result, generation of coarse Al oxide having a high melting temperature is observed, and the wettability as SnZn solder is inhibited. Therefore, it cannot be said that it is a preferable production method. (B): Component of additive added to SnZn molten metal In Table 1 (Reference Example 3) when Si is only Si, when charged into the SnZn molten metal, Si having a melting temperature exceeding 1400 ° C. does not diffuse quickly into the SnZn molten metal and the dispersibility of Si is poor. As a result, the formation of coarse Si oxide having a high melting temperature is observed, and the wettability as solder is hindered.
(C): When the component of the additive added to the SnZn molten metal is AlSi, in the case of an AlSi master alloy in which the ratio of Al to Si is less than 0.5, the flow of hot water of the AlSi master alloy itself As a result, the homogenization in the SnZn molten metal takes time, resulting in segregation of Al and Si, resulting in a SnZnAlSi solder having a high bonding strength reduction rate and a large variation, which is a preferable manufacturing method. Absent.
(D): In the case where the components of the additive added to the SnZn molten metal are Al and Si and the SiAl master alloy has a Si content exceeding 45%, the melting temperature of the AlSi master alloy itself is excessively increased. As a result, the flow of SnZn molten metal is inferior, and it takes time for homogenization, resulting in segregation of Al and Si, resulting in a SnZnAlSi solder with a high joint strength reduction rate and large variation, which is preferable manufacturing. It's not a method. Therefore, it becomes a preferable manufacturing method when the component of the additive added to the SnZn molten metal is an AlSi master alloy having a Si content of 0.5 to 45%.

    Second embodiment of the present invention: After the first step maintains Al at a temperature of 680 ° C. or higher and 1200 ° C. or lower, a predetermined amount of Si is allowed to act on the molten Al to obtain 1,000. 2. The method for producing a SnZnAlSi solder having a low rate of reduction in bonding strength according to claim 1, wherein an AlSi master alloy having a liquidus temperature of not higher than ° C. is prepared.

    That is, in the present invention, a predetermined amount of Si is allowed to act on the molten Al in a temperature atmosphere in which Al is maintained at 680 ° C. or more and 1200 ° C. or less, and the liquidus temperature is 1,000 ° C. or less and 0 Prepare an AlSi master alloy characterized by comprising 5 to 45% by weight of Si and the balance Al. The composition in the case where a CuSi alloy is used in combination as needed prepares a SiCu alloy containing 35% Si (first step). By causing a predetermined amount of Si to act on the molten Al, Al and Si in the SnZnAlSi solder are uniformly dispersed. Therefore, a method for producing a SnZnAlSi solder with less variation in the rate of decrease in bonding strength is provided.

    As shown above, when an AlSi master alloy containing 0.5 to 45% of Si is used as an additive, the flowability and wettability are improved to obtain a SnZnAlSi solder with a low rate of decrease in bonding strength and less variation. Thus, it can be said to be a preferable production method.

    Fourth Embodiment of the Present Invention: In the first step, the ratio of Si and Al in the AlSi master alloy added to SnZn is such that the amount of Si is 0.5 to 5 times the amount of Al. It is a manufacturing method of SnZnAlSi solder characterized by a certain thing.

That is, in the present invention, when the (Si / Al) ratio is less than 0.5 times, an undissolved portion is generated inside the joint. Conversely, when the (Si / Al) ratio exceeds 5 times, the melting point becomes unnecessarily high, which is not a good measure as an additive. Therefore, when the (Si / Al) ratio is 0.5 to 5 times, a good additive is obtained.
When the required amount of Si is insufficient, a CuSi alloy prepared in advance is used together with the AlSi mother alloy to compensate for the insufficient amount of Si. In order to obtain an appropriate melting temperature, it is important to use a CuSi alloy with 35% Si and the remaining Cu.

    Fifth embodiment of the present invention: In the first step, AlSi manufactured in advance at a cooling rate of 10 to 10,000 ° C./second until the molten AlSi master alloy is cooled to room temperature. 2. The method for producing a SnZnAlSi solder having a low bonding strength reduction rate according to claim 1, wherein a mother alloy is used.

That is, the present invention is characterized in that the cooling rate for melting the AlSi mother alloy is 10 to 10,000 ° C./second. This is useful as a means for producing an AlSi master alloy in which Al and Si have a fine and uniform structure. The use of such an AlSi master alloy having a fine and uniform structure as an additive to SnZn facilitates rapid diffusion into the SnZn molten metal and helps to uniformly distribute the SnZn. This is useful for a manufacturing method for manufacturing a SnZnAlSi solder with a low strength reduction rate and a small variation.
In order to obtain the AlSi master alloy in a molten state at a cooling rate of 10 to 10,000 ° C./second, cooling in a water-cooled container, collision with a rotating disk, and into space It can be easily manufactured by releasing it.
On the other hand, when the AlSi alloy in a molten state is kept warm and cooled at a rate of less than 10 ° C./second, it is not preferable because Al and Si are segregated. On the other hand, in order to cool the AlSi alloy in a molten state at a rate exceeding 10,000 ° C./second while being in contact with a refrigerant, for example, an economical burden becomes large, which is not a good idea.

    Sixth Embodiment of the Present Invention: In the third step, when the AlSi mother alloy is put into the molten SnZn alloy, the AlSi mother alloy is made of Sn foil, Zn foil, Al foil, Cu foil. The method for producing SnZnAlSi solder having a low rate of reduction in bonding strength according to claim 1, wherein the solder is added by being wrapped in any of the above.

    That is, the present invention provides a molten SnZn alloy in a state where the AlSi mother alloy is wrapped with any of Sn foil, Zn foil, Al foil, and Cu foil so that the molten atmosphere does not directly contact the AlSi mother alloy. Put in (add) and react rapidly while protecting. AlSi master alloy that suppresses contamination of AlSi master alloy from the melting atmosphere and oxidation of AlSi master alloy, and consequently reduces the amount of oxygen in SnZnAlSi solder and reduces the Zn oxide layer formed on the solder surface layer It is useful as a means of manufacturing.

Seventh embodiment of the present invention: In the third step, the AlSi master alloy or both the AlSi master alloy and the CuSi master alloy are added to the SnZn alloy in a molten state of 200 to 400 ° C. The method for producing SnZnAlSi solder having a low bonding strength reduction rate according to claim 1.
That is, since this manufacturing method has selected 200 to 400 ° C. as the addition temperature of the AlSi master alloy, it is effective in minimizing the AlSi master alloy from being excessively oxidized or denatured. The amount of oxygen in the manufactured SnZnAlSi solder can be controlled to 50 ppm or less, and a bonding strength of 10 N or more is ensured, so that a stable SnZnAlSi solder manufacturing method is obtained.
The lower limit of the amount of oxygen is 3 ppm from the viewpoint of productivity. If the amount of Si is less than 0.5% or the melting operation temperature in the first step when producing the AlSi master alloy is excessively high, the amount of oxygen exceeds 50 ppm, and the joint has pores. This is a method for producing SnZnAlSi solder in which the amount of oxygen in the solder is controlled to 3 to 50 ppm in order to cause generation and instability of bonding strength.

Action

In the SnZn solder material “Table 1” (Reference Example 1) not containing Al and Si, a large amount of Zn oxide is observed on the surface after bonding.
In order to solve the problem, SnZnAl solder material containing only a small amount of Al suppresses or reduces the formation of Zn oxide to some extent due to the presence of Al. It is observed that there are undissolved parts and pores (voids) centering on Zn oxide (Table 1) (Reference Example 2).
That is, in the SnZnAl solder material manufactured by a manufacturing method in which a small amount of Al is added alone to the SnZn molten metal, the presence of Al suppresses and reduces the formation of Zn oxide to some extent, but the solder inside after soldering, It is observed that there are still undissolved portions and pores (holes) centering on the Al oxide in a part of the portion.
Even in the SnZnSi solder material manufactured by adding Si alone to the SnZn molten metal, the formation of Zn oxide is suppressed and reduced to some extent by the presence of Si. In Table 1, it is observed that there are undissolved portions and pores (holes) centering on Zn oxide (Table 1).

In the manufacturing method in which a predetermined AlMg master alloy is added to the SnZn molten metal as an additive, the formation of fragile AlMg intermetallic compounds is recognized inside the bonded layer after bonding, and this is not a preferable manufacturing method.
On the other hand, the above-mentioned defect is suppressed in the SnZnAlSi solder material manufactured by the present manufacturing method in which a predetermined AlSi master alloy is added to the SnZn molten metal as an additive.
That is, in the manufacturing method using a predetermined ratio of AlSi master alloy as an additive, an important advantage is that Al and Si have a characteristic of showing a eutectic structure. And has a solidus temperature lower than 660 ° C., which is the melting point of Al, and the alloying is completed without leaving an unmelted portion. This is a characteristic obtained only when Al and Si are added together as an AlSi master alloy, and is an excellent manufacturing method "Table 1" (present invention).

As a result, the advantage of adding it as an AlSi master alloy is that it has the advantage of alloying with SnZn more rapidly than the manufacturing method of adding Al alone or Si alone, and the advantage of alloying at a lower temperature. As a result, in the SnZnAlSi solder This reduces the generation of unmelted parts in the solder and further contributes to the refinement of the solder structure after soldering. By this action, a method for producing a SnZnAlSi solder material having a low bonding strength reduction rate is obtained.
In the SnZnAlSi solder material in which AlSi coexists by the manufacturing method as described above, the above-mentioned problems of SnZn and SnZnAl are solved by a synergistic effect of simultaneously adding Si and Al in a predetermined AlSi master alloy. It is an excellent manufacturing method.
This manufacturing method is also applied to the step of coating the surface of the circuit board with the SnZnAlSi solder material.

When observing a solder layer left in a high-temperature and high-humidity environment at 85 ° C. and 85% humidity for 600 hours, SnZn solder (for example, 9% Zn balance Sn) according to the conventional manufacturing method without adding the AlSi mother alloy, Formation and coarsening of Zn oxide are caused by oxidation of Zn condensed on the surface layer. Moreover, the progress of cracks is observed along the interface between the Sn matrix and the coarsened Zn oxide inside the joint, leading to a reduction in joint strength. Furthermore, there is a large variation in the bonding strength depending on the size and amount of Zn oxide.
As described above, the effect of the AlSi master alloy in which Al and Si are present simultaneously is such that Al and Si are finely and uniformly dispersed, preventing the progress of cracks and further suppressing the decrease in bonding strength. . In addition, it contributes to fine and even distribution of the tissue. Another benefit is an improvement in the bonding strength variation width.

On the other hand, an AlSi master alloy manufactured with a small amount of Al and a small amount of Si corresponding to the amount of Al (the amount of Si with respect to Al is 0.5 to 5 times) is used as an additive. In the SnZnAlSi solder material manufactured by the manufacturing method of the present application according to the first process to the fourth process, generation of undesirable Zn oxide is suppressed.
However, for example, when Si is added as a 75% Al-25% Si master alloy, if Si is increased (increased), the amount of Al becomes higher, and the amount of Al in the AlSi master alloy and Si Since a preferable ratio range with respect to the amount (the amount of Si with respect to Al is 0.5 to 5 times) cannot be ensured, another alloy for increasing the amount of addition of Si is necessary, and the combined use of CuSi alloy is effective.

In the manufacturing method of the present invention in the manufacture of a SnZnAlSi solder material, a first step of preparing a CuSi master alloy together with an AlSi master alloy. A manufacturing method for manufacturing a SnZnAlSi solder material comprising: a second step of bringing SnZn into a molten state; and a third step of introducing the AlSi master alloy and CuSi master alloy into the molten SnZn molten metal. is there.
The CuSi master alloy is an alloy consisting of 35% Si and the balance being Cu. This adjusts the amount of Si in the SnZnAlSi solder material.

Comparison of manufacturing methods;
In the third step of the manufacturing method of the present invention, the conventional basic manufacturing method “Table 1” (Reference Example 1) for manufacturing SnZn solder without adding anything to the molten SnZn alloy. Manufacturing method “Table 1” (Reference Example 2) in which SnZn solder is manufactured by adding only Al to a molten SnZn alloy. Manufacturing method “Table 1” (Reference Example 3) in which SnZn solder is manufactured by adding only Si to a molten SnZn alloy. For each solder material manufactured by each of the manufacturing methods “Table 1” (Invention 1) of manufacturing an SnZn solder by adding an AlSi mother alloy to a molten SnZn alloy, the bonding temperature of each solder material is Table 1 shows a joining experiment in which the temperature was set to about 30 ° C. higher than the liquidus temperature.
The thickness of the Zn oxide formed on the surface layer and the degree of void formation were compared and measured by XMA and microscopic observation, and the results are shown in “Table 1”. The production method of the present invention exhibits a remarkable effect by adapting the AlSi master alloy to the production of SnZnAlSi.

    Furthermore, the advantage of the manufacturing method of the present invention when manufacturing the SnZn solder also contributes to the improvement of the bonding strength after being left in a high temperature and high humidity environment of 600 hours at 85 ° C. and 85% humidity. The degree of decrease in bonding strength after standing for 600 hours was in the range of about 5%.

    When only Al is added alone to the molten SnZn, Al is rapidly affected by a small amount of surrounding oxygen while melting, and Al becomes a highly viscous Al solution, which is extremely mobile (diffusion) in the SnZn molten metal. A part of the Al oxide having a high melting temperature, and as a result, the progress of alloying between the SnZn molten metal and the Al molten metal is delayed, resulting in an unmelted part. It can not be said that this is a preferable method for producing a solder material due to the formation of (mainly an Al oxide having a size exceeding 5 μm in width and width) and formation of a heterogeneous portion of the structure (“Table 1” reference example) 2).

    In the manufacturing method in which only Si is added alone to the SnZn molten metal, since Si has a very high melting temperature of 1440 ° C., Si does not readily melt and remains in a solid state, resulting in a non-uniform structure and the SnZn solder material. “Table 1” (Reference Example 3), which causes variations in mechanical properties and cannot be said to be a preferable method for producing a SnZn solder material.

    On the other hand, in the conventional basic manufacturing method for manufacturing SnZn solder without adding Al or Si to the SnZn molten metal, the formation of thick Zn oxide and a large number of pores are observed at the joint. "Table 1" (Reference Example 1) which is not a preferable production method.

    On the other hand, in the manufacturing method of the present invention having the configuration consisting of the first step to the fourth step, when an AlSi master alloy having a predetermined condition (finely dispersed) is added to the SnZn molten metal, the formation of Zn oxide is suppressed. However, the formation of the unmelted portion caused by Al as described above is eliminated, and the occurrence of the above problems is suppressed or reduced (this is less effective when Al alone or Sn alone is added). According to the manufacturing method of the present invention in which AlSi of a predetermined condition is added to SnZn, the effect of suppressing the amount of Zn concentrated in the SnZn solder surface layer (finally Zn oxide is formed on the surface portion) is beneficial. "Table 1" which functions in the present invention (the present invention and Examples 1 to 14 described later).

    When the SnZn solder is manufactured, an AlSi mother alloy is prepared, and the manufacturing method of the present invention in which it is added prevents the phenomenon of Zn concentration and elution of Zn when the solder hardens. That is, Zn is easily ionized and eluted, but when AlSi is finely concentrated on the surface, it is naturally difficult to dissolve Zn, and as a result, the corrosion resistance is further improved.

The invention's effect

    As described above, the first step of using the AlSi master alloy having a predetermined liquidus temperature manufactured by solidifying at a predetermined cooling rate as an additive into the SnZn molten metal and used for manufacturing the SnZnAlSi solder material In the manufacturing method including the fourth step, the synergistic effect of AlSi can suppress the aggregation of Zn generated inside the SnZn solder material, the generation of Zn oxide, and the generation of unmelted portions, It is possible to provide a method for producing a SnZnAlSi solder material having a uniform structure and a low rate of decrease in bonding strength and a small variation width.

BEST MODE FOR CARRYING OUT THE INVENTION

    Examples of the present invention will be shown below and will be described more specifically.

The present invention is a method for producing a SnZnAlSi solder material comprising four steps from a first step to a fourth step.
First step:
Hereinafter, a CuSi alloy is used in combination with an AlSi master alloy as necessary. First, in a melting furnace maintained at a furnace temperature of about 680 ° C. or more and about 1200 ° C. or less, AlSi master alloys (master alloys 1 to 4) including about 0.3% to 15% Si and the balance Al are prepared. did.
Furthermore, an AlSi master alloy (master alloy 5) comprising about 25% Si and the balance Al was prepared in a melting furnace maintained at a furnace temperature of about 800 ° C. or more and about 1200 ° C. or less.
Furthermore, an AlSi master alloy (master alloy 6) comprising about 30% Si and the balance Al was prepared in a melting furnace maintained at a furnace temperature of about 900 ° C. or more and about 1200 ° C. or less.
Further, an AlSi master alloy (master alloy 7) comprising about 35% Si and the balance Al was prepared in a melting furnace maintained at a furnace temperature of about 900 ° C.
Furthermore, an AlSi master alloy (master alloy 8) comprising about 50% Si and the balance Al was prepared in a melting furnace maintained at a furnace temperature of about 1100 ° C. or more and about 1200 ° C. or less.
In addition, as-formed AlSi can be used if it is sufficiently degassed.
Second step:
About the SnZn alloy containing about 15% or less of Zn content, it was in a molten state in a melting furnace maintained at about 300 ° C.
The SnZn alloy containing about 30% to 50% or less of Zn was put in a molten state in a melting furnace maintained at about 400 ° C.
About the SnZn alloy containing about 70% of Zn content, it was made into a molten metal state in a melting furnace maintained at about 450 ° C.
Third step:
100% Al, 100% Si, and each AlSi master alloy prepared in the first step are appropriately selected and put into each SnZn molten metal being melted in the second step, and Al, Si, and AlSi are put into SnZn. Disperse in (third step).
Fourth step:
The SnZn molten metal containing Al, the SnZn molten metal containing Si, and the SnZn molten metal containing AlSi were cooled and solidified to produce SnZnAl solder material, SnZnSi solder material, and SnZnAlSi solder material (fourth step).
In addition, when the purity of each material is not sufficiently good, or when the purity is not constant, and when the melting operation time is long or short, the amount of Al and Si after SnZn solder production generates oxide during the melting operation, And because it is consumed, it fluctuates.

なお，はんだ材中のＡｌ量とＳｉ量との比率を調整する為に、一部の試料についてはＳｉ量の調整の為に、ＡｌＳｉ母合金にＳｎＳｉ系合金を加える。ＳｎＳｉ系合金は、全組成に対して２３２℃の低い固相線温度を持つためＳｎＳｉ合金を添加材として活用するのが便利である。このＳｎＳｉ母合金も第１の工程と同様に準備できる。Joining conditions:
The prepared Al material was put into a ZnSn molten metal to produce SnZnAl solder for evaluation (Comparative Examples 1 and 5).
The prepared Si material was put into a molten ZnSn to produce an evaluation SnZnSi solder (Comparative Examples 2 and 6).
“Table 2”, “Table 3”, “Table 4”, and “Table 5” were manufactured by putting any of the mother alloys 1 to 8 selected from the prepared alloys into the ZnSn molten metal to produce SnZnAlSi solder for evaluation. (Comparative Examples 3-4, 7-16, Examples 1-14).

In order to adjust the ratio between the amount of Al and the amount of Si in the solder material, a SnSi-based alloy is added to the AlSi master alloy for adjusting the amount of Si for some samples. Since the SnSi alloy has a low solidus temperature of 232 ° C. with respect to the total composition, it is convenient to use the SnSi alloy as an additive. This SnSi master alloy can also be prepared in the same manner as in the first step.

Conditions for evaluating joint strength:
A comprehensive joint strength evaluation including actual assembly work was performed. A through-hole type composite substrate having a size of 150 mm width × 205 mm length × 1.5 mm thickness and a glass epoxy substrate were used as the substrate, and the surface thereof was subjected to a resist treatment. One component was a Cu lead (16 pins, 2.54 pitch) with a wire diameter of 0.6 mm coated with Au plating. In this case, it is difficult to accurately measure the bonding area between the lead wire and the bonded portion, but since the bonding area is almost the same, it was confirmed by a method of relatively comparing the bonding strength.
However, in this method, it is complicated to prepare for evaluation by using a substrate for each measurement. Therefore, as shown in FIG. By pulling in the direction of 45 ° (45 °), the bonding strength of the solder joint was confirmed. In addition, the joining strength in Tables 2-5 shows the measured value (N: Newton) about eight lead pins, The average value, the maximum value, and the minimum value were described. Since the bonding area (contact area) between the lead wire and the bonded portion is substantially the same, a relative comparison is possible.
When the bonding strength of Sn-38.1% Pb solder, which is the conventional standard, was measured with this bonding area, it showed a range of approximately 7 to 10 N. Therefore, 10 N is a guideline for the evaluation of the manufacturing method of the present invention. It was judged as good or bad.
In this experiment, using a soldering device in which the oxygen concentration was adjusted to less than 50 ppm and the solder materials shown in the table, the liquidus temperature of each solder material plus 30 ° C higher temperature was selected. Joined.

Comparison when Sn-38.1% Pb bonding strength is 1.0;
2.0 times or more (Evaluation S) Good 1.5 times or more to less than 2.0 times (Evaluation A) Good 1.2 times or more to less than 1.5 times (Evaluation B) Good 1.0 times or more Less than 1.2 times (Evaluation C) Good 0.8 times or more and less than 1.0 times (Evaluation W) Defect 0.5 times or more and less than 0.8 times (Evaluation X) Defect 0.3 times Above-less than 0.5 times (Evaluation Y) Defect Less than 0.3 times (Evaluation Z) Defect

Evaluation of variation width of joint strength measurement value; (ratio between maximum and minimum of 40 measured values)
Less than 20% (Evaluation a) Good 20% or more to less than 50% times (Evaluation b) Good 50% or more to less than 100% times (Evaluation c) Good 100% or more to less than 200% times (Evaluation d) Poor 200% or more (Evaluation e) Defect
Examples 1-4, Comparative Examples 1-6

“Table 2” (Comparative Example 1) was adjusted so that only Al was added to the SnZn molten metal and only 3 ppm of Al in Sn-9% Zn after melting remained.
And it adjusted so that only 3 ppm of Si amount in Sn-9% Zn after fusion | melting might remain | survived (Table 2) (comparative example 2). In Al (Comparative Example 1), it is easy to form an aggregate of highly viscous Al oxides. In Si (Comparative Example 2), high melting point Si remains in a solid state in SnZn, both of which are high-quality SnZn. It is not preferable as a manufacturing method for manufacturing a solder material ("Table 2"). As a result, the bonding strength under the above-described evaluation conditions is not preferable in that the average value is evaluation Y and the variation is evaluation d.
On the other hand, the bonding strength under the above-mentioned evaluation conditions in the AlSi master alloy with the Si amount of 0.5 to 30% was good as a manufacturing method because the average values were evaluations A to S and the variations were evaluations a to c. . However, the bonding strength when the Si amount is 35% and 50% is not preferable as a manufacturing method because the average value is evaluation Z and the variations are evaluations d to e.
Although a separately prepared SnSi alloy was also used, since the amount of Cu remaining in the solder is small and has little influence on the characteristics, the composition table in “Table 2” is prepared by excluding the amount of Cu.

That is, 100% Al, 100% Si (Comparative Examples 1-2). As an AlSi master alloy, Si amount is 0.1%, 0.2%, 0.5%, 4%, 15%, 30% (Comparative Examples 3 to 4. Examples 1 to 4). An AlSi master alloy containing 35% and 50% (Comparative Examples 5 to 6) was prepared (first step).
Next, after forming a SnZn molten metal (second step), the AlSi master alloy was charged into the molten metal, or Al and Si were charged (third step). These are cooled and solidified (fourth step) to obtain a SnZnAlSi solder material, a SnZnAl solder material, and a SnZnSi solder material.

    In the AlSi master alloy in which the amount of Si in the AlSi master alloy (not the amount of Si in the SnZn solder) is 0.5%, 4%, 15%, and 30% (Examples 1 to 4), cooling solidification is performed. According to observation of the internal structure of the solder when used as a solder material after the (fourth step), there is no undissolved Al, and Si is obtained in a SnZn homogeneous Al and a good SnZnAlSi solder in which AlSi is uniformly dispersed (implementation) Examples 1-4). It exhibits a bonding strength of 10N (Newton) or more and has a small variation width.

    However, in the AlSi master alloy in which the Si amount in the AlSi master alloy is 0.1% and 0.2% (Comparative Examples 1 and 2), the Si amount with respect to the Al amount is too small, and the Si amount is the target Si amount. Al is not more than 0.1%, and Al that functions to suppress the formation of Zn oxide is easily segregated, and aggregation of Al cannot be suppressed. Even if it is added to the SnZn molten metal, Al is contained in SnZn. Remains as an undissolved part and a good SnZnAlSi solder cannot be obtained, and there is a manufacturing complexity in adjusting the amount of Si (Comparative Examples 3 to 4). The bonding strength is extremely low.

Conversely, when an AlSi master alloy containing 35% and 50% Si (Comparative Examples 5 to 6) is used as an additive, high melting point Si does not melt sufficiently, and Si does not dissolve in the SnZn melt. It remains as a portion, a good SnZnAlSi solder cannot be obtained, and the bonding strength also varies widely.
Heating to a temperature of 1500 ° C. or more in order to melt the undissolved portion of Si causes excessive evaporation loss of Si. The composition of each solder obtained after the fourth step is shown in “Table 2”.
Examples 5-8, Comparative Examples 7-9

In Examples 1 to 4, the amount of Zn in the SnZn solder was about 9%. While adjusting the Zn content in the range of 1.3 to 90.3%, SnZnAlSi solder materials having the compositions shown in Table 3 were manufactured. In this experiment, the target was to contain Al and Si in the obtained SnZnAlSi solder material at approximately 3 to 5 ppm of Al and 5 to 18 ppm of Si. In order to control the ratio of Al and Si amounts to the target values, a separately prepared SnSi alloy was also used. However, since the amount of Cu remaining in the solder is small and has little influence on the characteristics, the composition shown in Table 3 is used. The table is prepared excluding the Cu amount.
When the amount of Zn in the SnZn solder is 3 to 50%, “Table 3” (Examples 5 to 8), the joint strength under the above evaluation conditions is an average value of evaluation S to C, and variation is evaluated to be b to c. The method was good.
SnZnAlSn Solder materials with various SnZn compositions with the goal of containing Al and Si in the same manner as in the previous examples, and containing 3 to 5 ppm Al and 5 to 18 ppm Si. did. The composition of each solder obtained after the fourth step is shown in “Table 3” (Examples 5 to 8).
When the Zn content in the SnZn solder is 1.3%, a SnZnAlSi solder having a large variation in bonding strength is obtained (Comparative Example 7). Further, SnZn solders with Zn content of 60% and 90% cause excessive increase in liquidus temperature and decrease in joint strength characteristics, and are excluded from solder materials to which the manufacturing method of the present invention is applied (Comparison Examples 8-9).
On the other hand, the production of the SnZn solder material containing 3 to 50% of Zn by applying the production method of the present invention showed stable characteristics in both joint strength and joint strength variation, as shown in “Table 3” ( Examples 5-8).
Examples 9-10, Comparative Examples 10-13

    In Examples 5 to 8, the influence on the bonding strength characteristics was investigated for the manufacture of solder materials having an Al amount of 3 to 6 ppm and an Si amount of about 3 to 18 ppm finally remaining in the SnZn solder material. However, the manufacturing method of the present invention is beneficial even when the Al content finally remaining in the SnZn solder material is 3 to 20 ppm and the Si content is expanded to 5 to 30 ppm. (Examples 9 to 10).

The prepared master alloy is selected. When the amount of Al in the solder after manufacture is 30 ppm and the amount of Si is 3 to 8 ppm (Comparative Example 10), the average value of the bonding strength is evaluated W, and the variation thereof is greatly evaluated d.
Further, when the Al amount is 70 and the Si amount is 3 to 10 ppm (Comparative Example 11), the average value of the bonding strength is in a favorable range in the evaluation C, but the variation is greatly large and becomes an evaluation e. There is no way. This is because the Al amount is significantly larger than the Si amount and there is an unmelted portion.
On the other hand, the amount of Al in the solder after manufacture is 3 to 4 ppm, and the amount of Si is 5 to 7 ppm (Example 9). When the Al amount is 17 to 20 ppm and the Si amount is 27 to 30 ppm (Example 10), the average value of the bonding strength is evaluated S to A, and the variation is also evaluated a to b, indicating excellent bonding strength characteristics. . This is a manufacturing method for obtaining a uniform solder structure with very few unmelted portions.
However, when the Al amount in the manufactured solder is 8 to 11 ppm, the Si amount is 68 to 75 ppm (Comparative Example 12), the Al amount is 13 to 15 ppm, and the Si amount is 95 to 125 ppm (Comparative Example 13), Even if the amount of Si is excessive, the presence of an unmelted portion of high melting point Si is observed, which is also unfavorable, resulting in a decrease in bonding strength and a large variation width.

From the above, the manufacturing method of the present invention is a SnZnAlSi solder material in which the amount of Si in the manufactured SnZn solder is 5 to 30 ppm and the amount of Al is 3 to 20 ppm (5 ppm ≦ Si ≦ 30 ppm. 3 ppm ≦ Al ≦ 20 ppm). It applies to the manufacturing method to manufacture (Examples 9-10). In this range, the relative bonding strength exceeded 20 N, and the manufacturing method had little variation.
On the other hand, when the Al amount is 30,70 ppm (Comparative Examples 10 to 11) and the Si amount is 68 to 75, 95 to 125 ppm (Comparative Examples 12 to 13), the relative bonding strength is lower than 20 N and the variation width is also large. It became a big manufacturing method. The composition of each solder is shown in “Table 4”.
Examples 11-15, Comparative Examples 14-17

The effect of the (Si / Al) ratio on the bonding strength characteristics was investigated for the manufacture of solder materials with an Al content of 3 to 20 ppm and an Si content of 2 to 30 ppm finally remaining in the SnZnAlSi solder material. However, when the (Si / Al) ratio is in the range of 0.5 to 5 times (Examples 11 to 14), the average value of the bonding strength under the evaluation conditions is evaluation S to B, and the variation is evaluation b to It became c and it was favorable as a manufacturing method.
However, when the Si / Al ratio is 0.2 times (Comparative Example 14), there is an unmelted Al portion, and when the Si / Al ratio is 8.4 times (Comparative Example 17), there is an unmelted Si portion. This is not preferable for the bonding strength characteristics. In Comparative Example 14, the amount of Si exceeds 100 ppm, and the presence of an unmelted Si portion is also recognized, which is not preferable for the bonding strength characteristics.
The results are shown in “Table 5”.

From the above, as a manufacturing method for manufacturing SnZnAlSi in which the ratio of the amount of Al remaining in SnZnAlSn to the amount of Si (Si / Al ratio) is in the range of 0.5 to 5 times, an AlSi master alloy is used as an additive. To do.
Comparative Examples 18-19

It is necessary to control the amount of oxygen in the SnZnAlSi solder to 3 to 50 ppm. When the amount of oxygen in the SnZnAlSi solder exceeds 50 ppm (Comparative Example 18), the bonding strength is less than 10N. If it is less than 3 ppm (Comparative Example 19), there is no problem in the bonding strength, but the productivity is inferior and variation is seen, so it is excluded. The SnZnAlSi solder shown in Examples 1 to 15 has an oxygen amount of 3 to 50 ppm.
Examples 16-17

    In the fourth step of the manufacturing method of the SnZnAlSi solder of the present invention, the circuit board having the necessary conditions is immersed in the melted SnZnAlSi, and the required circuit board surface is coated with the SnZnAlSi solder. (Example 16). In the fourth step of the method of manufacturing the SnZnAlSi solder of the present invention, a method of manufacturing a circuit board in which SnZnAlSi being melted is irradiated or sprayed with SnZnAlSi solder on a required portion of the surface of the circuit board with the necessary conditions ( Examples 17) and the like are included.

    As described above, the manufacturing method of the present invention is a highly safe SnZnAlSi solder material that does not contain Pb for joining electronic, electrical, or mechanical parts by adding an AlSi master alloy having a predetermined condition to the molten SnZn. The manufacturing method at the time of manufacturing can be provided.

    Illustration explaining the evaluation method of the joining method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 To-be-joined object 3 Solder material 4 Lead pin 5 Insulation clothing layer 6 Special pulling jig 7 Direction of pull

Claims (7)

First step, a second step of Zn amount is melted the SnZn alloy is 3 to 50 wt% the balance includes Si 0.5 to 30% by weight is prepared beforehand the AlSi base alloy consisting of Al, the The AlSi master alloy is put into the molten SnZn alloy, and the third step of diffusing and dispersing AlSi in the SnZn alloy, cooling and solidifying, the oxygen amount is 3 to 50 ppm, the Al amount is 3 to 3 A method for producing a SnZnAlSi solder having a low bonding strength reduction rate, comprising the fourth step of producing a SnZn alloy in which only 20 to 30 ppm and an Si content of 5 to 30 ppm are left.     In the first step, an AlSi master alloy having a liquidus temperature of 850 ° C. or lower is obtained by simultaneously acting the predetermined amount of Al and Si in an atmosphere maintained at a temperature of 680 ° C. or higher and 1200 ° C. or lower. The method for producing a SnZnAlSi solder having a low rate of decrease in bonding strength according to claim 1, wherein the method is prepared.     In the first step, Al is maintained at a temperature not lower than 680 ° C. and not higher than 1200 ° C., and then a predetermined amount of Si is allowed to act on the molten Al, whereby an AlSi matrix having a liquidus temperature of 850 ° C. or lower. An alloy is prepared, The manufacturing method of SnZnAlSi solder with a low joint-strength decreasing rate of Claim 1 characterized by the above-mentioned.     The ratio of Si and Al in the AlSi master alloy in the first step (Si / Al) ratio is 0.5 to 5 times. A manufacturing method of SnZnAlSi solder.     2. The bonding according to claim 1, wherein in the first step, the AlSi master alloy is manufactured at a cooling rate of 10 to 10,000 ° C./second until the AlSi alloy in a molten state is cooled to room temperature. A method for producing SnZnAlSi solder having a low strength reduction rate.     In the third step, when the AlSi master alloy is put into the molten SnZn alloy, the AlSi master alloy is added by being wrapped in one of Sn foil, Zn foil, Al foil, and Cu foil. The method for producing a SnZnAlSi solder having a low bonding strength reduction rate according to claim 1.     2. The joint strength reduction according to claim 1, wherein in the third step, the AlSi master alloy is added to a SnZn alloy in a molten state of 200 to 600 ° C., preferably 200 to 400 ° C. 3. Manufacturing method of SnZnAlSi solder with low rate.

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