JPWO2014021308A1 - Solder alloy for metal bonding and soldering method using the same - Google Patents

Abstract

To provide a high melting point soldering metal alloy capable of good soldering joining to many metals and a soldering method using the same. Solder alloy for metal bonding comprising Zn as a main component, further comprising 1.0 to 5.0 mass% Al and 0.01 to 0.5 mass% Si Alloy and soldering method using the same.

Description

  The present invention relates to a solder alloy used for all metal materials, and more particularly to a solder alloy mainly composed of Zn.

  With solder, the melting point is lower than the target base material and the alloy composition is set so that sufficient bonding is possible, and the raw materials that are the alloy components are heated and melted, and appropriate according to the soldering method It is an alloy that has been solidified into a simple shape.

  When joining metal materials using solder, the necessary properties are that the solder is melted by heating and soldering is performed properly, the strength and corrosion resistance are excellent even after joining, and the work is easy and From the economical aspect, it is desired that both the solder alloy and the operation cost are inexpensive. Today, with the development of electronics, the joining technology for joining electronic devices has dramatically advanced, and it is possible to join chip components represented by a component size of 0.4 mm × 0.2 mm.

  In fields other than electronics, there are friction soldering methods represented by aluminum joining. The friction soldering method is a method of removing oxides existing on the aluminum surface by heating the metal material to be soldered, making the solder in a semi-molten state, and rubbing from above with a stainless spatula. . However, the friction soldering method can be performed only in the case of joining aluminum and aluminum. In joining of aluminum and dissimilar metal (metal other than aluminum), pre-soldering is performed on the dissimilar metal side beforehand using a flux. There is an unavoidable method of cleaning, removing and removing the flux residue, and further heating and melting the aluminum and the dissimilar metal side solder.

  Examples of dissimilar metals that cannot be soldered using flux include titanium and titanium alloys, and cemented carbides such as high-speed steel. Materials that cannot be soldered depend on welding and the like. If the material of the solder has to be changed according to the material of the adherend, the productivity is lowered, and as a result, the solder joint can be separated. In addition, the concept of soldering is completed, resulting in a slowdown in technological evolution.

In the case where soldering is not possible, a stubborn oxide typified by Cr ₂ O ₃ is formed on the surface of stainless steel. Such oxides are stable and difficult to remove with flux. If oxide remains at the interface between the bonded solder and metal, soldering will not occur.

  In soldering, it is necessary to first remove the oxide on the surface of the joining metal, and then supply molten solder to the joint, so that the atoms of both metals diffuse to form an alloy layer. . When bonding is insufficient, oxide remains at the interface, but the oxide present at the interface cannot be visually confirmed. When the oxide remains in the soldered portion, the bonding strength is lowered, and when energized, the conductivity is lowered to cause heat generation.

  By the way, a solder alloy containing Zn and Al is known as a solder alloy conventionally used (for example, Patent Document 1). In the case of a solder alloy containing Zn and Al, when the Al content is around 5% by mass, the melting point is around 380 ° C., which is the eutectic point of Zn—Al (see FIG. 1). Further, when the Al content is 5% by mass or less, the lower the Al content, the higher the melting point and the temperature can be raised to a high temperature of 390 ° C. or higher. However, when measured with a differential scanning calorimeter, the eutectic point (380 ° C. From the fact that an endothermic peak is observed in the vicinity), it can be confirmed that melting has started at the stage of the eutectic point.

  The temperature of a device such as an automobile that is exposed to a high temperature for a long operating time may reach 300 ° C. or higher. If the melting point is near the eutectic point, the solder may melt and the device may be damaged. For these reasons, development of a solder alloy having a high melting point is desired.

  The Zn alloy described in Patent Document 2 has a high melting point of 390 ° C. or higher by setting the Al content to 1% by mass or less. However, when Al is contained in the solder component, when soldering a base material made of aluminum or an aluminum alloy, the base material is eroded due to excessive zinc in the solder component, so that the solderability to aluminum is inferior.

Japanese Patent Laid-Open No. 9-225678 JP 2006-167748 A

  Accordingly, it is an object of the present invention to provide a high melting point soldering metal alloy capable of good soldering and joining to many metals and a soldering method using the same.

  As a result of intensive studies by the present inventors to solve the problems of the present invention, the above object is a solder alloy for metal bonding mainly composed of Zn, and further comprising 1.0 to 5.0% by mass. It has been found that this is achieved by a solder alloy for metal bonding characterized by containing Al and 0.01 to 0.5% by mass of Si.

  Preferred embodiments of the solder alloy for metal bonding of the present invention are as follows.

(1) Further containing 0.3 to 2% by mass of Ni.
Thereby, an alloy in which the melting of the eutectic of Zn—Al is not confirmed can be produced.
(2) It further contains at least one element selected from the group consisting of Ge, Co, Cu, Cr, Mn and Fe in an amount of 0.05 to 2.0% by mass.
(3) Further containing Ge and / or Fe in an amount of 0.05 to 2.0 mass%.
(4) The Al content is 1.0 to 3.0 mass%.
(5) The Si content is 0.1 to 0.3% by mass.
(6) The Zn content is 90% by mass or more.

  Moreover, the said objective is achieved by the soldering method using the solder alloy for metal joining of this invention.

  Preferred embodiments of the soldering method of the present invention are as follows.

(1) Friction soldering method.
(2) Perform using a flux containing an inorganic compound containing halogen.
(3) the flux comprises at least LiCl, the KCl and ZnCl _2.

  The solder alloy of the present invention is capable of joining aluminum with metals such as stainless steel, nickel, copper, titanium, and alloys such as brass as well as joining aluminum members, and various soldering not limited to aluminum, Can be used for brazing applications. And since the solder alloy of this invention has high melting | fusing point, it can be used suitably as a solder alloy used for the apparatus exposed to high temperature, such as a motor vehicle.

It is a Zn-Al phase diagram. It is an Al-Si phase diagram. It is a Zn-Si phase diagram.

  The metal bonding solder alloy of the present invention will be described in detail below. The metal-bonding solder alloy of the present invention contains Al in an amount of 1.0 to 5.0% by mass, Si in an amount of 0.01 to 0.5% by mass, and, if necessary, additional elements described later, with the remainder being the main component. Zn.

  Components other than Zn in the present invention have the following effects. Al has a function of improving the oxidation of Zn and the embrittlement of Zn (Zn has poor spring property and is brittle). If the oxidation of the molten metal at a high temperature can be suppressed, the yield will be improved. The presence of Al in Zn is indispensable as an antioxidant action when melted. A metal or alloy having a high melting temperature generally has high strength. The Sn—Zn alloy has a melting point as low as 199 ° C., and experience shows that the strength is lower than that of an alloy having a higher melting point than this alloy. This alloy is effective in improving strength by adding a metal having a higher melting point based on zinc. On the other hand, the higher the melting point, the greater the oxidation of the metal during formation.

  In developing a solder alloy containing Zn as a main component, it was found that oxidation was remarkable in the region exceeding the melting point of Zn, which was not suitable for actual work. By adding Si, the melting point of Zn increases, and oxidation can be suppressed. Si has a high melting point of 1410 ° C. and reacts with oxygen at 900 ° C. or higher, but in the molten state, it forms many metal alloys or silicides and has a function of suppressing the formation of metal oxides. For this reason, oxidation of zinc and zinc alloy and entanglement of oxide occur in the process of manufacturing solder, and Si is effective in preventing these. Oxidation is inevitable if heating is performed in the atmosphere, since it is always heated and melted by soldering in actual work after the alloy is manufactured. However, the solder alloy to which Si is added can prevent the oxidation of Zn by preferentially reacting with Si by depriving of oxygen during the melting of the solder even in the work in the atmosphere. Can be made. Since the solder alloy of the present invention operates at relatively high temperatures, reliability is how to prevent oxidation.

  Also, assuming soldering work, the solidus line is 382 ° C. in the Zn—Al phase diagram in which zinc is the main component and the melting point for adding aluminum to this is 419.5 ° C. This eutectic temperature region exists in the range of 82.8 to 98.86% by mass of Zn from the Zn—Al phase diagram (FIG. 1). The eutectic region of the alloy phase diagram of this system has a constant solidification end temperature (melting start temperature) of 382 ° C. Since the composition may vary in the practical stage, the solder material is easy to work at a constant temperature of 382 ° C. during the heating and cooling processes. In FIG. 1, an internal transformation occurs at 275 ° C., and unless this transformation is suppressed, there is a risk that uneven heating will occur due to the soldering of the material to be joined having a large volume. As a result of trial manufacture to solve these problems, the addition of Ni was effective. Ni has the effect of suppressing melting at the eutectic point in addition to the effect of suppressing transformation.

  The content of Al in the solder alloy of the present invention is 1.0 to 5.0 mass%, preferably 1.0 to 3.0 mass%, more preferably 1.5 to 2.0 mass%. If the amount is less than 1.0% by mass, the effect of addition of Al is not observed, and a large amount of oxide is generated. Moreover, when it exceeds 5.0 mass%, not only melting | fusing point will fall but solderability will also fall.

  The content of Si in the solder alloy of the present invention is 0.01 to 0.5% by mass, preferably 0.1 to 0.5% by mass, and more preferably 0.1 to 0.3% by mass. If it is less than 0.01% by mass, the effect of addition of Si is not observed, and a large amount of oxide is generated during soldering. Moreover, when it exceeds 0.5 mass%, melting | fusing point will become high and will cause the yield fall by hot water flow deterioration. Further, from the Al—Si phase diagram of FIG. 2, Si has a high melting point, but since the eutectic is formed with Al at a predetermined ratio (Al: Si = 1: 8 to 10), the melting point is lowered. On the other hand, since the melting point decrease due to the eutectic formation does not occur in the Zn—Si phase diagram of FIG. 3, the melting of Si is easier than the melting with Al first than the single melting.

  The solder alloy of the present invention preferably contains Ni. The content of Ni is 0.3 to 2.0% by mass, preferably 0.5 to 1.5% by mass. When the Ni content is less than 0.3% by mass, the effect of adding Ni may not be sufficiently obtained, and a solder alloy having a transformation point or a eutectic point may be obtained. On the other hand, when the Ni content is more than 2.0% by mass, metal melting becomes difficult, and a large amount of oxide is generated, which may reduce the yield.

  In order to improve the mechanical properties and reliability of the solder, the solder alloy of the present invention includes at least one selected from the group consisting of Ge, Co, Cu, Cr, Mn and Fe in addition to Al, Si and Ni. You may add the above further element. The content of further elements is 0.05 to 2.0% by weight, preferably 0.05 to 1.0% by weight, particularly preferably 0.05 to 0.2% by weight. Within this range, it is possible to obtain a solder alloy that can be satisfactorily soldered without causing deterioration in hot-water flow and an increase in melting point.

  The content of Zn, which is the main component of the present invention, is the balance other than the above-described Al, Si, Ni and other elements, and is usually 90% by mass or more.

  The solder alloy of the present invention is a high melting point solder alloy having a melting point of 390 ° C. or higher, preferably 400 ° C. or higher. The upper limit of the melting point is not particularly limited, but is advantageously 500 ° C. or less from the viewpoint of workability. The solder alloy of the present invention may contain inevitable impurities that may occur during the manufacturing process. The shape of the solder alloy can be appropriately selected depending on the application, for example, a linear shape, a strip shape, a powder shape, or the like.

  The soldering method using the solder alloy of the present invention can be performed by a method similar to the conventional method. A friction soldering method, an ultrasonic soldering method, or a soldering method using a flux is preferable.

  In the friction soldering method, the solder is brought into direct contact with the metal adherend by grinding and removing the surface oxide film by mechanical friction while bringing the molten solder into contact with the surface oxide film of the metal adherend. This is a soldering method for adhering by diffusion. In addition, the ultrasonic soldering method uses the cavitation generated by ultrasonic vibration to peel and remove the surface oxide film while bringing the molten solder into contact with the surface oxide film of the metal adherend. This is a soldering method in which an adherend is brought into direct contact and bonded by diffusion of metal atoms.

  In the soldering method using a flux, it is preferable to use a flux containing an inorganic compound containing a halogen. By using this flux, the effect of the solder alloy of the present invention can be exhibited to the maximum.

The inorganic compound containing halogen is a metal halide, preferably an alkali metal halide. This metal is preferably selected from K, Li and Zn. Halogen is preferably chlorine or fluorine. Specific examples of the inorganic compound containing halogen include LiCl, KCl, ZnCl ₂ , LiF, and KF.

Particularly preferred flux is a flux comprising at least LiCl, the KCl and ZnCl _2. A more preferred flux is a flux containing LiCl, KCl, ZnCl ₂ and KF. Highly preferred flux is a flux comprising LiCl, KCl, and ZnCl _2, KF and LiF.

The content of each component in the flux is 10 to 40% by mass of LiCl, preferably 10 to 35% by mass, 10 to 40% by mass of KCl, preferably 28 to 40% by mass, 20 to 40% by mass of ZnCl ₂ , It is preferable that LiF is 0.01 to 5 mass%, preferably 2 to 4 mass%, and KF is 0.01 to 15 mass%, preferably 3 to 10 mass%. When this blending ratio is not satisfied, the flux does not function sufficiently and may cause non-wetting.

Hereinafter, the present invention will be described with reference to examples.
<Preparation of solder alloy>
Put the raw materials with the composition shown in Tables 1 and 2 into a container, heat them to the melting point or higher and melt them. After confirming that there is no undissolved material, remove the oxides sufficiently with a spatula and pour the molten metal into the mold. And cooled to obtain a solder alloy.

<Evaluation method>
1. Measurement of melting point Using a DSC thermal differential analyzer, the peak temperature of the output chart was taken as the melting point.

2. Solder spread test 1) Measure 0.3 g of the solder alloy prepared above and 0.1 g of flux on each 30 × 30 mm test piece, heat on a hot plate at 500 ° C., and 30 seconds after melting the solder Until heated. Composition of the flux used were, LiCl 30 weight%, KCl 40 mass%, ZnCl ₂ 20 mass%, KF is 7% by mass, LiF is 3 wt%.

  2) The spread ratio of the solder was measured according to JIS Z 3198. The evaluation was based on the presence / absence of solder bonding and the spreading rate. As the base material, Al, Ni, Cu and Ti were used as the pure metals, and iron alloys (stainless steel) and copper alloys (brass) were used as the alloys. Among the evaluations, x indicates that the solder alloy was not bonded to the base material. The results are shown in Tables 1 and 2.

3. Solderability test by flux soldering 1) A solution in which flux of the composition shown in Table 3 is mixed on a 1 mm thick, 30 × 30 mm aluminum plate in a mass ratio of flux: water: IPA = 8: 1: 1 0.05 g was adhered, and further 0.1 g of the solder produced in Example 1 was placed thereon and heated by gas.
2) The case where the solder spreads immediately after melting the solder is indicated as “◯”, the case where 5 seconds or more have passed before the solder is melted and spread out is indicated as “Δ”, and the case where the solder did not melt is indicated as “X”. The results are shown in Table 3.

  In the solder spread test, in the comparative example, it was not bonded to Ti, stainless steel, and brass in all the examples except the comparative example 2, but it was recognized that one or more of them were bonded in the examples. In particular, Example 6 containing Ge and Example 11 containing Fe also had a high melting point, and it was confirmed that they were bonded to all the base materials. Moreover, in Examples 3, 4, and 6 to 11 containing Ni, it was confirmed that there was no eutectic point.

  Furthermore, when the solder spread test was performed on the solder alloys of the combinations of Comparative Examples 1 to 4 and Examples 1 to 11 under the same conditions except that the temperature condition 500 ° C. of the hot plate of the solder spread test was changed to 560 ° C., Except for Comparative Example 2, almost the same results as those shown in Tables 1 and 2 were obtained. In Comparative Example 2, it was confirmed that the aluminum melted and the holes were opened.

Results object present inventors to solve the have conducted extensive studies of the present invention, the above object is 1. 0 to 5.0 wt% of Al, see contains 0.01 to 0.5 mass% of Si and 0.3 to 2.0 wt% of Ni, and the balance being Zn and unavoidable impurities It has been found that this is achieved by a solder alloy for metal bonding. By including 0.3 to 2% by mass of Ni, an alloy in which the melting of the eutectic of Zn—Al is not confirmed can be produced.

(1 ) It further contains at least one element selected from the group consisting of Ge, Co, Cu, Cr, Mn and Fe in an amount of 0.05 to 2.0% by mass.
( 2 ) Further containing Ge and / or Fe in an amount of 0.05 to 2.0 mass%.
( 3 ) The Al content is 1.0 to 3.0 mass%.
( 4 ) The Si content is 0.1 to 0.3% by mass.
( 5 ) The Zn content is 90% by mass or more.

Claims (11)

A solder alloy for metal bonding mainly composed of Zn,
Furthermore, 1.0-5.0 mass% Al and 0.01-0.5 mass% Si are included, The solder alloy for metal joining characterized by the above-mentioned.   The solder alloy for metal bonding according to claim 1, further comprising 0.3 to 2.0% by mass of Ni.   The at least one element selected from the group consisting of Ge, Co, Cu, Cr, Mn, and Fe is further included in an amount of 0.05 to 2.0% by mass. Solder alloy for metal bonding.   The solder alloy for metal bonding according to claim 1 or 2, further comprising Ge and / or Fe in an amount of 0.05 to 2.0 mass%.   5. The solder alloy for metal bonding according to claim 1, wherein the content of Al is 1.0 to 3.0% by mass.   The content of Si is 0.1-0.3 mass%, Solder alloy for metal joining of any one of Claims 1-5 characterized by the above-mentioned.   7. The solder alloy for metal bonding according to claim 1, wherein the Zn content is 90% by mass or more.   The soldering method using the solder alloy for metal joining of any one of Claims 1-7.   The soldering method according to claim 8, wherein the soldering method is a friction soldering method.   The soldering method according to claim 8, wherein the soldering is performed using a flux containing an inorganic compound containing halogen. The soldering method according to claim 10, wherein the flux includes at least LiCl, KCl, and ZnCl ₂ .

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