JP2017051984A - Solder alloy and solder composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solder alloy and a solder composition which can prevent blacking after solder while maintaining wettability and corrosion resistance.SOLUTION: The present invention provides a solder alloy comprising Sn, Bi, and at least one metal selected from the group consisting of Co and Ag, with a content of Bi of 10 mass% or more and 80 mass% or less, and a content of the metal of 0.005 mass% or more and 6.5 mass% or less.SELECTED DRAWING: None

Description

  The present invention relates to a solder alloy and a solder composition.

  In recent years, so-called lead-free solder alloys that do not contain lead have been widely known as solder alloys used for mounting electronic components on a substrate. As a lead-free solder alloy, generally an alloy containing Sn-Ag as a main component, an alloy containing Sn-Cu as a main component, an alloy containing Sn-Ag-Cu as a main component, and the like are known. These alloys have a problem of high melting point. As an alloy for lead-free solder having a relatively low melting point, there is an alloy containing Sn-Bi as a main component (hereinafter also referred to as Sn-Bi alloy).

  However, since Sn—Bi alloys are easily oxidized, when soldering is performed using a solder composition using such a solder alloy, darkening may occur in a joint after soldering. Such darkening may be detected as an error in, for example, an appearance inspection of a product after soldering. In such a case, the product may be determined as a defective product.

As a method for suppressing darkening in a solder alloy mainly composed of Sn—Bi, for example, a solder alloy to which a small amount of Al is added is described in Patent Document 1.
However, even the solder alloy described in Patent Document 1 has a problem that blackening cannot be sufficiently suppressed.

JP 2013-248664 A

  This invention is made | formed in view of the problem of the above-mentioned prior art, and makes it a subject to provide the solder alloy and solder composition which can fully suppress the blackening after soldering.

The solder alloy of the present invention is a solder alloy comprising Sn, Bi, and at least one metal selected from the group consisting of Co and Ag,
The Bi content is 10% by mass or more and 80% by mass or less, and the metal content is 0.005% by mass or more and 6.5% by mass or less.

  Such a solder alloy is a solder alloy composed of Sn, Bi, and at least one metal selected from the group consisting of Co and Ag, and the content of Bi and the metal is in the above range, When used in a solder composition as a solder alloy, darkening after soldering can be sufficiently suppressed.

  In the present invention, the metal may be Co, and the Co content may be 0.005 mass% or more and 0.3 mass% or less.

  When the metal is Co and the content of Co is within the above range, darkening after soldering can be more sufficiently suppressed.

  In the present invention, the metal is Co and Ag, and the Co content is 0.005 mass% to 0.3 mass%, and the Ag content is 0.1 mass% to 4.0 mass%. There may be.

  In the present invention, when the metal is Co and Ag and the content of Ag is within the above range, darkening after soldering can be more sufficiently suppressed.

  The solder alloy of the present invention is a solder alloy comprising Sn, Bi, Sb, and at least one metal selected from the group consisting of Co, Ag, and Ni, and the Bi content is 10% by mass. The total of the Sb content and the metal content is 0.1% by mass or more and 6.5% by mass or less.

  The solder alloy is a solder alloy composed of Sn, Bi, Sb, and at least one metal selected from the group consisting of Co, Ag, and Ni, and the content of Sb and the metal is within the above range. Therefore, when used as a solder alloy in a solder composition, darkening after soldering can be sufficiently suppressed.

  In this invention, 0.5 mass% or more and 6.3 mass% or less of Sb content may be sufficient.

  When the Sb content is within the above range, darkening after soldering can be more sufficiently suppressed.

  In the present invention, the metal may be Co, and the Co content may be 0.005 mass% or more and 0.3 mass% or less.

  When the metal is Co and the Co content is within the above range, darkening after soldering can be more sufficiently suppressed.

  In the present invention, the metal may be Ag, and the Ag content may be 0.1% by mass or more and 4.0% by mass or less.

  When the metal is Ag and the content of Ag is within the above range, darkening after soldering can be more sufficiently suppressed.

  In the present invention, the metal is Co and Ni, the Co content is 0.005 mass% to 0.3 mass%, and the Ni content is 0.05 mass% to 0.2 mass%. There may be.

  When the metal is Co and Ni and the content of Co and Ni is in the above range, darkening after soldering can be more sufficiently suppressed.

  The solder composition according to the present invention includes any one of the above solder alloys and a flux.

  ADVANTAGE OF THE INVENTION According to this invention, the solder alloy and solder composition which can fully suppress the blackening after soldering can be provided.

4 is an optical micrograph of the test piece of Example 3. The optical microscope photograph of the test piece of the comparative example 27.

  Below, the solder alloy and solder composition concerning the present invention are explained.

  The solder alloy according to the present embodiment is a solder alloy composed of Sn, Bi, and at least one metal selected from the group consisting of Co and Ag.

The solder alloy according to the present embodiment is a lead-free solder alloy containing Sn-Bi as a main component.
In the present embodiment, the lead-free solder is a lead-free solder defined in JIS Z 3282.

The Bi content is 10% by mass or more and 80% by mass or less, preferably 10% by mass or more and 70% by mass or less.
When the Bi content is in the above range, a low melting point solder alloy containing Sn-Bi as a main component can be obtained.

The solder alloy of this embodiment contains at least one metal selected from the group consisting of Co and Ag, in addition to Sn and Bi as the main components.
The total content of the metal in the solder alloy is 0.005% by mass to 6.5% by mass, preferably 0.01% by mass to 6.3% by mass.
The solder alloy of this embodiment can suppress darkening after soldering by including the metal in the above-described content range.

  The metal may be Co. In such a case, the Co content is 0.005 mass% or more and 0.3 mass% or less, preferably 0.01 mass% or more and 0.1 mass% or less, more preferably 0.01 mass% or more and 0 mass% or less. 0.05% by mass or less.

The metal may be Co and Ag.
In this case, the content of each metal is 0.005 mass% or more and 0.3 mass% or less, preferably 0.01 mass% or more and 0.1 mass% or less, more preferably 0.005 mass% or less. It is 01 mass% or more and 0.05 mass% or less, and content of Ag is 0.1 mass% or more and 4.0 mass% or less, Preferably, it is 0.3 mass% or more and 3.0 mass% or less.

The balance of the solder alloy of this embodiment is Sn.
In addition, in the remainder of the solder alloy of this embodiment, inevitable impurities other than Sn may be included in the range which does not inhibit the effect of the solder alloy of this embodiment.

Furthermore, another solder alloy of the present embodiment is a solder alloy composed of Sn, Bi, Sb, and at least one metal selected from the group consisting of Co, Ag, and Ni.
In this case, the total content of Sb and the metal is 0.1% by mass to 6.5% by mass, preferably 0.5% by mass to 6.3% by mass.
The solder alloy of the present embodiment can sufficiently suppress darkening after soldering by including each of the metals in the above-described content range.

In this case, the metal may be Co.
In such a case, each metal has a Co content of 0.005 mass% or more and 0.3 mass% or less, preferably 0.01 mass% or more and 0.1 mass% or less, more preferably 0.01 mass% or more. It is 0.05 mass% or less.

In this case, the metal may be Ag.
Each metal in such a case has an Ag content of 0.1% by mass to 4.0% by mass, and preferably 0.3% by mass to 3.0% by mass.

Further, the metal in this case may be Co and Ni.
In such a case, each metal has a Co content of 0.005 mass% or more and 0.3 mass% or less, preferably 0.01 mass% or more and 0.1 mass% or less, more preferably 0.01 mass% or more. It is 0.05 mass% or less, and Ni content is 0.05 mass% or more and 0.2 mass% or less, Preferably it is 0.005 mass% or more and 0.1 mass% or less.

  The content of each metal contained in the solder alloy of the present embodiment is a value measured by ICP emission spectroscopic analysis (method described in JIS Z3910).

  The melting temperature of the solder alloy of this embodiment is 110 ° C. or higher and 200 ° C. or lower, preferably 135 ° C. or higher and 180 ° C. or lower. When the melting temperature of the solder alloy is within the above temperature range, the reflow temperature can be set to an appropriate range. In addition, the melting temperature of the solder alloy as used in this embodiment means solidus temperature.

  Furthermore, the solder alloy of this embodiment can be in various shapes such as powder and rod.

Next, an embodiment of the solder composition of the present invention will be described.
The solder alloy of this embodiment can be a solder composition containing a solder alloy and a flux.

The flux is not particularly limited, and examples thereof include rosin flux, synthetic resin flux, and water-soluble flux. From the viewpoint of safety in waste disposal and manufacturing processes, a halogen-free or low-halogen flux is preferred.
In addition, the low halogen flux as used in this embodiment means the flux whose halogen density | concentration in a flux is 1500 ppm or less, Preferably it is 900 ppm or less.

A general lead-free solder alloy made of a Sn-Bi alloy is difficult to suppress oxidation of Bi when a solder composition is manufactured using a low halogen flux, and in particular, it is difficult to suppress darkening of the appearance after soldering. There is a problem.
However, since the solder alloy of this embodiment can sufficiently suppress darkening, blackening is hardly generated even when a solder composition is manufactured using a low halogen flux.

  The solder composition of the present embodiment has a flux of 5% by mass to 25% by mass, preferably 8% by mass to 20% by mass, and the solder alloy powder of 75% by mass to 95% by mass, preferably 80% by mass. It is preferable that the paste is a solder paste mixed with 92% by mass or less.

  The solder composition of this embodiment can sufficiently suppress the occurrence of darkening after soldering.

Further, even when an electronic component is mounted on a substrate using the solder composition of the present embodiment, solder wettability and soldering corrosion resistance do not decrease.
Therefore, the solder alloy and the solder composition of the present embodiment can suppress darkening without deteriorating the solder characteristics.

  Although the solder alloy and solder composition concerning this embodiment are as above, it should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  Next, examples of the present invention will be described together with comparative examples. In addition, this invention is limited to a following example and is not interpreted.

(Solder alloy)
A solder alloy having each composition shown in Table 1 was prepared by the following method.
《Solder alloy manufacturing method》
Among the metals shown in Table 1 other than Sn, refractory metals Co and Ni that are difficult to melt into Sn at 600 ° C. are adjusted to the mass% of Table 1 and added to Sn melted at 1000 ° C. Hold for 1 hour or longer and cast with an ingot mold.
Among the metals listed in Table 1, the low melting point metals Cu, Bi, Sb, Ge, Ag, Ga, and In, which are easily melted into Sn at 600 ° C., are adjusted so that the mass% is listed in Table 1. , Added to Sn melted at 600 ° C., held as it is for 1 hour or longer, and then melted into an ingot mold.
When a high melting point metal element and a low melting point metal are included, the high melting point metal is added to Sn melted at 1000 ° C. as described above, and then the melt of Sn and low melting point metal melted at 600 ° C. Is added to, and kept as it is for 1 hour or more, and then melted into an ingot mold.

<Measurement method of darkening>
Each solder ingot obtained by the above method was pulverized and pulverized, and observed by the following method to measure the presence or absence of darkening.
A solder paste obtained by mixing each solder powder and a low halogen rosin flux at a ratio of 20 wt% is screen-printed on a Cu plate so as to have a width of 4 mm, a depth of 2 mm, and a thickness of 200 μm. It was produced as a test piece that was soldered to a Cu plate by heating at 30 ° C. for 30 seconds to melt the solder alloy and cooled to room temperature at about 4 ° C./second.
The test specimen was observed with an optical microscope, and “black” was generated when darkening that could be visually identified was generated, and “none” when no blackening was observed.
As the optical microscope, KH-8700 manufactured by Hilox was used.
The results are shown in Table 1.

As is apparent from Table 1, no darkening was observed in the solder alloys of the examples.
On the other hand, darkening was observed in the solder alloys of the comparative examples.

In addition, the photograph which image | photographed the test piece of Example 3 was shown in FIG. 1, and the test piece which image | photographed the test piece of the comparative example 27 was shown in FIG. The picture was taken at a magnification of 50 times.
1 and 2, it can be seen that in the test piece of Example 3, the black line (darkening) around the solder that appeared in the test piece of Comparative Example 27 did not appear at all.

《Wetting test》
Solder alloy powder formed so as to have a composition of each metal shown in Table 2 was prepared as a solder paste in the same manner as described above.
Using each solder paste, the point A (the point where the recording line intersects the reference line and the force applied to the test piece is zero) shown in the test method of JIS Z 3197 “Wetting Balance Method”. Time) was measured as “zero crossing time”. The shorter the wetting time (zero crossing time), the faster the wetting and the better the wettability.
The results are shown in Table 2.

  As is clear from Table 2, each example had a short wetting time (zero crossing time) or equivalent compared to each comparative example.

Claims (9)

A solder alloy comprising Sn, Bi, and at least one metal selected from the group consisting of Co and Ag,
A solder alloy having a Bi content of 10% by mass to 80% by mass and a metal content of 0.005% by mass to 6.5% by mass.   The solder alloy according to claim 1, wherein the metal is Co, and the Co content is 0.005 mass% or more and 0.3 mass% or less.   The metal is Co and Ag, and the Co content is 0.005% by mass to 0.3% by mass, and the Ag content is 0.1% by mass to 4.0% by mass. Solder alloy described in 1. A solder alloy comprising Sn, Bi, Sb, and at least one metal selected from the group consisting of Co, Ag and Ni,
The solder alloy whose Bi content is 10 mass% or more and 80 mass% or less, and the sum total of content of Sb and said metal content is 0.1 mass% or more and 6.5 mass% or less.   The solder alloy according to claim 4, wherein the Sb content is 0.5 mass% or more and 6.3 mass% or less.   The solder alloy according to claim 4 or 5, wherein the metal is Co, and the Co content is 0.005 mass% or more and 0.3 mass% or less.   The solder alloy according to claim 4 or 5, wherein the metal is Ag, and the Ag content is 0.1 mass% or more and 4.0 mass% or less.   The metal is Co and Ni, and the Co content is 0.005 mass% to 0.3 mass%, and the Ni content is 0.05 mass% to 0.2 mass%. Or the solder alloy of 5.   A solder composition comprising the solder alloy according to claim 1 and a flux.