WO2019035197A1

WO2019035197A1 - Solder alloy for preventing fe erosion, flux cored solder, wire solder, flux cored wire solder, flux-coated solder and solder joint

Info

Publication number: WO2019035197A1
Application number: PCT/JP2017/029531
Authority: WO
Inventors: 基泰鬼塚; 陽子倉澤; 俊策吉川; 岳齋藤
Original assignee: 千住金属工業株式会社
Priority date: 2017-08-17
Filing date: 2017-08-17
Publication date: 2019-02-21
Also published as: JPWO2019035197A1; JP6344541B1; CN109673149A; PH12018501147A1; CN116174992A

Abstract

Provided are a solder alloy for preventing Fe erosion, a flux cored solder, a wire solder, a flux cored wire solder, a flux-coated solder and a solder joint which, in order to prolong the life of a soldering iron tip, suppress erosion of the soldering iron tip and by which adhesion of carbides to the soldering iron tip is suppressed. The present invention: includes an alloy composition comprising, in terms of mass%, 0.2-4.0% of Ag, 0.1-1.0% of Cu, 0.01-0.04% of Co, 0.025-0.1% of Ni and 0.007-0.015% of Fe, with the remainder comprising Sn; and has suppressed adhesion of carbides to a soldering iron tip and is used for Fe erosion prevention.

Description

Solder alloys for solder corrosion prevention, core solder, wire solder, core solder, flux coating solder, and solder joints

TECHNICAL FIELD The present invention relates to a solder alloy for preventing iron corrosion which can suppress corrosion of a tip and carbonization of a flux, core solder, wire solder, core wire solder, flux coated solder, and a solder joint.

Sn-Ag-Cu based lead-free solder alloys are mainly used for connection of terminals such as printed circuit boards. Sn-Ag-Cu based lead-free solder alloys are used in various processes such as flow soldering, reflow soldering, and soldering using a solder pot.

Soldering using a soldering iron includes manual soldering such as manual soldering. In recent years, the automation of soldering using a soldering iron has been advanced, and soldering has been performed automatically by a trowel robot.

The solder crucible is composed of a heating element and a tip, and the heat of the heating element is conducted to the tip to heat the tip. In order to efficiently conduct the heat of the heating element to the point, Cu having a good thermal conductivity is used as the core material of the point. However, when the solder comes in direct contact with Cu, Cu is eaten by Sn in the solder alloy, and the shape of the tip is deformed, making it difficult to use as a solder iron. Therefore, in order to suppress erosion by Sn, the erosion is coated with Fe and Fe alloy plating.

As described above, although the coating with Fe and Fe alloy plating is applied to the coating from the viewpoint of extending the life of the coating, the coating of the coating surface is coated as the number of solderings increases by the automation of the soldering. Eating has come to occur. The cause of the occurrence of corrosion of Fe and Fe alloy is that Sn and Fe in the solder alloy are alloyed by mutual diffusion and it becomes easy to dissolve in Sn in the molten solder. For this reason, there is a limit in the handling of the solder pot side, and a solder alloy in which the occurrence of Fe corrosion is suppressed has been studied.

Patent Document 1 proposes an alloy in which 0.1 mass% or more of Co is added to a Sn—Ag—Cu-based solder alloy. When Fe is added to a solder alloy, a Sn-Fe alloy is formed even if the content is very small. Therefore, in the invention described in Patent Document 1, 0.1% of Co belonging to the same Group 8 as Fe is used. By adding at least mass%, diffusion of Fe into the solder alloy is suppressed, and Fe corrosion can be prevented.

Patent No. 4577888 gazette

As described above, since the solder alloy described in Patent Document 1 contains 0.1% by mass or more of Co, Co disperses in the solder alloy and suppresses the diffusion of Fe into the solder alloy. It is possible to extend the previous life.

However, it has been found that as the life of the tip extends, new problems arise. Co also has the property of being easy to react with carbon, although it suppresses Fe eating. For this reason, when soldering is performed several thousand times, the problem of the carbide adhering to the point has surfaced.

Also, in soldering using a soldering iron, a flux based on rosin is generally used to break the oxide film on the terminal surface to make the solder easy to wet, and when soldering, together with the solder Rosin is also heated. At this time, Co in the solder alloy reacts with the carbon and oxygen of the rosin to form a large amount of carbides and causes the carbides to adhere to the forehead. The carbide adheres to the crucible due to a chemical reaction with Co, so it is difficult to remove the carbide from the crucible even by air cleaning. Therefore, as the frequency of use increases, the adhesion area of carbides increases, and eventually, soldering becomes difficult.

The subject of the present invention is a solder alloy for preventing iron corrosion, in which adhesion of a carbide to a tip is suppressed in order to suppress tip erosion for prolonging the life of the tip, core solder, wire solder An object of the present invention is to provide a core wire solder, a flux coating solder, and a solder joint.

The inventors of the present invention, in the alloy composition described in Patent Document 1, reduced the amount of adhesion of carbides to the tip due to the reduction of the Co content, but Fe corrosion was gradually generated as the Co content was reduced. I started. Therefore, in order to simultaneously achieve the prevention of Fe corrosion of the tip and the suppression of adhesion of carbides to the tip, the present inventors are to inhibit Fe corrosion in an alloy composition with a reduced Co content. Study was carried out.

In order to reduce the Fe content while reducing the Co content, it is conceivable to add Ni, which is a transition metal of the same family. Although Ni causes the melting point of the solder alloy to rise to form a compound with Sn, the addition of a small amount of Ni to such an extent as to compensate for the reduction of the Co content hardly causes the above-mentioned problems due to the large addition of Ni. However, the addition of only a small amount of Ni can not exert a sufficient Fe eating suppression effect.

Therefore, as a result of the addition of a small amount of Fe, which has been conventionally avoided, in order to form a compound with Sn without forming any solid solution in Sn, the present inventors accidentally suppress Fe corrosion. At the same time, it was found that the adhesion of carbides to the tip of the crucible was also suppressed.

In addition, the above study also shows that even if a large amount of Fe is added in addition to a large amount of Co, it reacts with the carbon and oxygen of rosin to generate a large amount of carbides as with Co, and thus knowledge that carbonization is promoted is obtained. The

In addition to these, it was found that when the Ag content in the alloy composition was increased, the wettability of the solder alloy was dramatically improved.

The present invention obtained by these findings is as follows.
(1) Ag: 0.2 to 4.0% by mass, Cu: 0.1 to 1.0%, Co: 0.01 to 0.04%, Ni: 0.025 to 0.1%, A solder alloy for preventing corrosion of iron according to claim 1, characterized in that it has an alloy composition comprising Fe: 0.007 to 0.015% and the balance being Sn.

(2) The solder alloy for preventing Fe corrosion as described in the above (1), which contains Ag: 2.3 to 4%.

(3) The core solder which has the solder alloy for Fe corrosion prevention as described in said (1) or said (2).

(4) A wire solder comprising the solder alloy for preventing Fe corrosion according to the above (1) or (2).

(5) The core wire solder which has the solder alloy for Fe corrosion prevention as described in said (1) or said (2).

(6) The flux coated solder according to any one of the above (1) to (5), wherein the surface of the solder is coated with a flux.

(7) A solder joint having the solder alloy for preventing Fe corrosion according to (1) or (2) above.

The invention is described in more detail below. In the present specification, “%” relating to the solder alloy composition is “% by mass” unless otherwise specified.

1. Alloy composition (1) Ag: 0.2 to 4.0% or less Ag is an element capable of improving the wettability of a solder alloy. When the content of Ag is 0.2% or more, the wettability is remarkably improved. Further, if the Ag content is 0.2% or more, in addition to the above effects, the melting temperature of the solder alloy is lowered, so that the set temperature of the solder can be lowered, and additionally, the occurrence of Fe corrosion is generated. Can also be suppressed. The lower limit of the Ag content is preferably 1.0% or more, and particularly preferably 2.3% or more. On the other hand, when the Ag content exceeds 4.0%, coarse compounds of SnAg crystallize out and cause defects such as bridges when soldering is performed. The upper limit of the Ag content is 4.0% or less, preferably 3.5% or less.

(2) Cu: 0.1 to 1.0%
Cu is an element capable of suppressing corrosion of the electrode when the material of the electrode is Cu. In order for Cu to exhibit the above effect, the lower limit of the Cu content is 0.1% or more, preferably 0.3% or more, and more preferably 0.5% or more. On the other hand, if the Cu content exceeds 1.0%, the soldering iron temperature can not be set in the temperature range of the soldering operation temperature (240 ° C. to 450 ° C.), and the thermal of the electronic parts to be soldered It will cause damage. The upper limit of the Cu content is 1.0% or less, preferably 0.7% or less.

(3) Co: 0.01 to 0.04% or less Co is an element that suppresses Fe corrosion. In order for Co to exhibit the above effect, the lower limit of the Co content is 0.01% or more, preferably 0.020% or more, and more preferably 0.025% or more. On the other hand, when the Co content exceeds 0.04%, carbonization is promoted because it reacts with carbon and oxygen of rosin to form a large amount of carbides. The upper limit of the Co content is 0.04% or less, preferably 0.035% or less.

(4) Ni: 0.025 to 0.1% or less Ni is an element capable of suppressing the corrosion to Fe. Moreover, Ni can improve the fatigue resistance of the solder alloy in addition to the above effects. In order to sufficiently exert these effects, the lower limit of the Ni content is 0.025% or more, preferably 0.035%. In addition, when the Ni content exceeds 0.1%, a compound with Sn is formed, the melting point of the solder alloy rises, and the solder temperature is kept within the temperature range of the soldering operation temperature (240 ° C to 450 ° C). It can not be set, causing thermal damage to the electronic component to be soldered. The upper limit of the Ni content is 0.1% or less, preferably 0.7% or less, and more preferably 0.5% or less.

(5) Fe: 0.007 to 0.015%
Fe is an effective element to suppress the elution of Fe into the solder alloy and to prevent the corrosion of the Fe alloy that covers the tip of the solder crucible. These effects can not fully be exhibited as Fe content is less than 0.007%. The lower limit of the Fe content is 0.007% or more, preferably 0.009% or more, and more preferably 0.010% or more. On the other hand, when the Fe content exceeds 0.015%, the occurrence of carbonization is promoted and a large amount of carbides adheres to the tip. Further, the melting temperature of the solder alloy becomes too high, and the set temperature of the solder crucible must be raised, which is not preferable from the viewpoint of the heat resistance temperature of the electronic component to be soldered. The upper limit of the Fe content is 0.015% or less, preferably 0.013% or less, and more preferably 0.011% or less.

(6) Remainder: Sn
The remainder of the solder alloy according to the invention is Sn. In addition to the above elements, unavoidable impurities may be contained. Even when including inevitable impurities, the above-mentioned effects are not affected. In addition, as described later, even if an element not contained in the present invention is contained as an unavoidable impurity, the above-mentioned effect is not affected.

2. Melting Temperature of Solder Alloy The solder alloy according to the present invention preferably has a melting temperature of 350 ° C. or less. This is because the tip temperature is usually heated to 350 to 450 ° C. during soldering with a soldering iron.

3. Ladder Solder, Wire Solder, Ladder Wire Solder, Flux Coated Solder The solder alloy according to the present invention is suitably used for core solder which has flux in advance. Moreover, it can also be used in the form of wire solder from the viewpoint of supplying solder to the crucible. Furthermore, it is also possible to apply to flux core solder in which flux is sealed in flux solder. Furthermore, flux may be coated on the surface of each solder. In addition to this, the flux may be coated on the surface of the solder having no flux in the solder.

The flux content in the solder is, for example, 1 to 10% by mass, and the rosin content in the flux is 70 to 95%. In general, since rosin is an organic compound and contains carbon and oxygen, the present invention is not limited to terminal functional groups and the like.

4. Solder Joint Further, “solder joint” in the present invention means a connection portion of an electrode, and the connection portion is formed of the solder alloy according to the present invention. Moreover, Cu, Ni, and Al are mentioned as a material of an electrode, The electrode by which Ni / Au plating was given to Cu electrode may be sufficient.

Solder alloys shown in Table 1 were produced. It was confirmed that all of these solder alloys have a melting temperature of 350 ° C. or less. The solder alloy was used to form a core solder and to evaluate Fe corrosion and carbonization. The evaluated results are shown in Table 1.
<Fe eaten>
Using an automatic soldering machine (JAPAN UNIX (registered trademark), UNIX (registered trademark) -413S), the tip temperature is 380 ° C., the solder feed speed is 10 mm / sec, and the solder feed amount is 1 shot. Soldering was performed in the air at 15 mm in the air, and while the air cleaning was performed on the tip once every 10 shots, Fe erosion of the tip was evaluated. The crucible used has a model number of P2D-R manufactured by JAPAN UNIX (registered trademark), and the surface of Cu, which is the core of the crucible, is plated with Fe with a thickness of 500 μm. Moreover, as for the core solder, the flux content in the solder was 3% by mass, and the rosin content in the flux was 90%.

In the evaluation method of Fe corrosion, at 25000 shots, a hole was opened in the Fe plating on the tip, and a state in which Cu of the core material was exposed was "X", and a state in which the hole was not open was "O".
<Carbonization>
Using an automatic soldering machine (JAPAN UNIX (registered trademark) UNIX (registered trademark) -413S), the tip temperature is 380 ° C., the solder feed speed is 10 mm / sec, and the solder feed amount is 1 shot. The soldering was carried out at 15 mm, and the carbonization of the tip was evaluated while performing air cleaning once every 10 shots. The used core solder is used in the evaluation of Fe corrosion.

In the evaluation method of carbonization, a state in which carbide was not attached to the Fe-plated portion of the tip at 5000 shots was regarded as "○○". At 3000 shots, the state in which no carbide was attached to the Fe-plated portion of the tip was regarded as “o”. The state in which carbides were attached to the Fe-plated portion of the tip at 3000 shots was taken as "x". When carbide adheres to the Fe plated portion of the tip, the contact area with the solder becomes small, and the solderability deteriorates.
<Zero cross time>
The zero crossing time was measured by the solderability test method by Meniscograph. Test conditions are based on JIS Z3197.

Temperature: melting point + 35 ± 3 ° C
Flux: RMA02 manufactured by Senju Metal Industries, Ltd.
Immersion depth: 2 mm, immersion speed: 20 mm / sec
Immersion time: 10 sec
Dimensions of feed material: 30 x 10 x 0.3 mm
Material: Cu
Less than 1.0 seconds is "○ ○", more than 1.0 seconds and less than 1.3 seconds is "○", and more than 1.3 seconds is "X".

As shown in Table 1, in each of Examples 1 to 23, the evaluation of "A" and "C" was evaluated as "Good", "Good" and "Good", respectively. The time evaluation was also ○ or ○. In particular, in Examples 1 to 13 in which the Ag content is 2.3% or more, good wettability was shown.

On the other hand, in Comparative Examples 1 and 3, the carbon content was x because the Co content was high. For this reason, evaluation of Fe eating was not performed.

In Comparative Example 2 and Comparative Example 4, the Fe corrosion was x because they do not contain Ni and Fe.

Comparative Example 5 had x wettability because it did not contain Ag.
In Comparative Example 6, carbonization was x because the Fe content was high.

The solder alloy according to the present invention is particularly suitable when soldering is performed several thousand times or more with a soldering iron. In the case of soldering by the iron robot, since the number of times of soldering reaches several thousand times immediately, it is possible to suppress the carbonization of rosin caused by the extension of the life of the soldering iron.

In Comparative Example 7, carbonization was x because the Fe content was high.
In Comparative Example 8, carbonization was x due to the high Co content.

Comparative Example 9 was Fe-poor x because it did not contain Fe.

Claims

Ag: 0.2 to 4.0% by mass, Cu: 0.1 to 1.0%, Co: 0.01 to 0.04%, Ni: 0.025 to 0.1%, Fe: 0 A solder alloy for preventing corrosion of iron, which has an alloy composition comprising 007 to 0.015% and the balance being Sn, in which adhesion of carbide to a tip of a tip is suppressed.
The solder alloy for preventing Fe corrosion according to claim 1, wherein Ag: 2.3 to 4% is contained.
A core solder containing the solder alloy for preventing Fe corrosion according to claim 1 or 2.
A wire solder comprising the solder alloy for preventing Fe corrosion according to claim 1 or 2.
A core wire solder comprising the solder alloy for preventing Fe corrosion according to claim 1 or 2.
The flux-coated solder according to any one of claims 1 to 5, wherein the surface of the solder is coated with a flux.
The solder joint which has the solder alloy for Fe corrosion prevention of Claim 1 or 2.