JP2016087670A - Solder material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solder material sealing the container of a surface mounting component and having a low liquidus temperature and a high solidus temperature.SOLUTION: A solder material is constituted as a solder paste where solder powders consisting of a quinary alloy of 32 mass% or less of Sn, 10 mass% or more and 17 mass% or less of Sb, 1 mass% or more and 4 mass% or less of Cu, 1 mass% or more and 9 mass% or less of In and the balance Ag and a flux are mixed. Therefore, solidus temperature becomes 260°C, preferably 280°C or higher, and liquidus temperature becomes 350°C or lower. The solder material having a difference between the solidus temperature and the liquidus temperature of, for example, within 60°C is realized, and it is suitable for sealing a mounting component.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solder material.

For example, a small electronic component such as a surface acoustic wave device or a crystal resonator is housed in a small container, configured as a surface mount component, and mounted on a substrate such as a wiring board.
At this time, a solder material is used as a sealing material for hermetically sealing the container of the surface mounting member.

In the process of mounting such a surface mounting component on the surface of the wiring board, for example, a surface mounting solder material is applied between the electrode pad of the surface mounting component and the electrode formed on the wiring board, and the reflow furnace For example, a reflow process of heating to a temperature around 260 ° C. is performed. The solder for surface mounting is melted by this reflow process, and the electrode pads of the surface mounting component and the electrode terminals of the wiring board are electrically connected.
However, if the solidus temperature, which is the temperature at which the solder material sealing the container is solidified, is low, the solder material will be remelted in the reflow process, and it will no longer be airtight in surface mount parts that require reduced pressure airtightness. The internal pressure may increase and the lid of the container may come off.

Therefore, the solder material used for sealing the surface-mounted component container is required to have a solidus temperature higher than 260 ° C. at which the solder material solidifies. Furthermore, in the step of sealing the surface mount component container, it is necessary to prevent melting of the adhesive for fixing the small component housed in the surface mount component. Therefore, since the solder material used as a sealing material is required to melt at the lowest possible temperature, the liquidus temperature is required to be low.
In addition, for products that are sealed by vacuuming the inside of the container, heating is performed in a vacuum atmosphere to melt the solder material, and then cooling and solidifying to seal the product. Because it is small, it takes a long time for cooling. For this reason, when the difference between the solidus temperature and the liquidus temperature is large, there is a problem that it takes a long time to seal the container.

As a sealing material for such a container, conventionally, a solder material in which gold and tin having a eutectic point at about 280 ° C. are used has been used. However, since gold is expensive, a solder material that does not use gold has been demanded in recent years. Further, as another example of a suitable solder material, a solder material using lead is known. However, a solder material not using lead is demanded in consideration of the environment.
Patent Document 1 describes a solder material whose main material is bismuth (Bi) having a solidus temperature of 255 ° C. or higher. However, Bi has a property that its volume expands at room temperature, and is not suitable as a sealing material that hermetically seals the gap between containers.

WO 2007/055308

  The present invention has been made under such circumstances, and an object thereof is to provide a solder material having a low liquidus temperature and a high solidus temperature.

The solder material of the present invention consists of at least a ternary alloy containing Sn, Ag, Cu, Sb and In,
The solidus temperature is higher than 260 ° C., for example, 280 ° C. or higher, the liquidus temperature is 350 ° C. or lower, and the liquidus temperature is higher than the solidus temperature. The solder material preferably has a temperature difference between the liquidus temperature and the solidus temperature within 60 ° C.

  More specifically, the solder material includes Sn of 32% by mass or less, Sb of 10 to 17% by mass, Cu of 1 to 4% by mass, In of 1 to 9% by mass, and the balance containing Ag and inevitable impurities. But you can. Furthermore, the solder material may be in the form of a paste mixed with a flux, or may be a preform that has been processed into a metal foil and then punched out.

  The solder material of the present invention is composed of at least a ternary alloy containing Sn, Ag, Cu, Sb and In, and by adjusting the amount of each component, the solidus temperature is higher than 260 ° C., for example at 280 ° C. or higher. Yes, the liquidus temperature can be 350 ° C. or lower, and the liquidus temperature can be higher than the solidus temperature. For this reason, for example, it is suitable as a solder material for sealing surface-mounted components.

It is a differential scanning calorific value curve of the solder material concerning Example 14. 10 is a differential scanning calorimetry curve of a solder material according to Example 9.

  First, the solder according to the present invention will be described with reference to preferred embodiments. The solder material according to the present embodiment includes Sn (tin) of 32 mass% or less, Sb (antimony) of 10 mass% or more and 17 mass% or less, and Cu (copper) of 1 mass% or more and 4 mass% or less. 1% by mass or more and less than 9.5% by mass, for example, 9% by mass or less of In (indium) and a solder powder composed of a ternary alloy consisting of Ag (silver) constituting the balance. It is comprised as a paste-like solder paste formed.

Sn is a dominant factor that determines the solidus temperature of the solder material. The larger the Sn composition ratio in the solder powder, the lower the solidus temperature. Since the solder material of the present invention is intended to set the solidus temperature to a temperature exceeding 260 ° C., for example, 280 ° C. or more, the Sn composition in the solder powder is preferably 32% by mass or less.
In is a dominant factor that determines the liquidus temperature, and as the composition ratio of In increases, the liquidus temperature tends to decrease. Since the solder material of the present invention is intended to set the liquidus temperature to 350 ° C. or lower, the In composition in the solder powder is preferably 1% by mass or more. However, as the In composition ratio increases, the solid content increases. Since the phase line temperature also decreases and the temperature range in which a solid-liquid state is reached widens and the liquidus line temperature tends to become unstable, it is preferably less than 9.5% by mass, and preferably 9% by mass or less. Even more preferred.

  Ag has an effect of maintaining the stability of the joining of the solder material. Good joint stability means that soldering is performed using the solder paste, and then the solder paste has high mechanical strength when melted and solidified. More specifically, in a surface-mounted component, it means that the bonding strength between the substrate and the lid is strong when the substrate and the lid are bonded with the solder paste.

  Cu has the effect of allowing the crystals between the compositions to conform. To adapt the crystals means to strengthen the bond between the crystals of each metal in the solder material. However, when Cu is added excessively, the melting temperature of the produced solder paste is significantly increased. Then, it adjusts so that 1 mass% or more and 4 mass% or less may be contained with respect to solder powder.

Further, for example, in a solder paste containing a large amount of Ag and Cu, the eutectic point becomes high and eutectic is likely to be formed at the time of forming the solder paste, but the eutectic point is lowered by adding, for example, 10% or more of Sb. This is preferable because it can be performed. However, if the composition ratio of Sb is too large, Sb is recrystallized in the molten solder paste, and crystals are scattered, so that the quality of the solder is lowered. Therefore, the composition of Sb in the solder powder is 17% by mass or less. It is preferable.
In addition, in order to improve the fluidity of the solder paste and to increase the mechanical strength of the solder paste, the solder paste includes trace elements such as Si, Ti, Ni, Fe, Mo, Cr, Mn, Ge, and Ga. In a range not exceeding 1%.

  A method for manufacturing a solder material according to an embodiment of the present invention will be described. 32 mass% or less Sn, 10 mass% or more, 17 mass% or less Sb, 1 mass% or more, 4 mass% or less Cu, 1 mass% or more, less than 9.5 mass%, for example, 9 mass% An ingot is produced by dissolving the metal powder containing the following In and mixing the remainder so as to be Ag, and then kneading. Each metal powder is preferably pulverized into particles.

  As a method for forming the particulate metal powder, for example, a known pulverizer such as a turbo mill, a roller mill, a centrifugal pulverizer, or a pulverizer can be used. The particle diameter of these metal powders is preferably in the range of an average particle diameter of 5 μm to 50 μm with a sphere equivalent diameter using a known particle size distribution measurement method such as particle image measurement or zeta potential measurement. When the particles are too large, the printability of the generated solder paste on the substrate is deteriorated, and when the particles are too small, the solder paste is heated and the wettability of the solder paste is deteriorated.

Subsequently, in vacuum, for example, a gas atomization method in which an ingot is melted in a heated crucible and sprayed in an air current such as nitrogen gas, or an ingot melted in a rotating plate shape rotating at high speed is continuously supplied, and centrifugal force A centrifugal spray atomizing method is used in which molten metal is sprayed around the rotating plate by using the above-mentioned.
As the flux constituting the solder paste, a flux containing a tackifier resin such as rosin, a thixotropic agent, an activator, a solvent and the like can be used. It can be used regardless of the difference in activity of the flux. Such solder powder and flux are mixed to produce a solder paste.

The solder material according to the above-described embodiment includes 32 mass% or less of Sn, 10 mass% or more, 17 mass% or less Sb, 1 mass% or more, 4 mass% or less Cu, 1 mass% or more, Since solder powder composed of a ternary alloy consisting of less than 9.5 mass%, for example, 9 mass% or less of In, and Ag constituting the balance is used, the solidus temperature is 260, as can be seen from the examples described later. A solder powder having a liquidus temperature of 350 ° C. or higher and a liquidus temperature higher than the solidus temperature can be obtained. For this reason, the solder material of the present invention can be manufactured at low cost, and is suitable as a solder material for sealing surface-mounted components.
Alternatively, the solder material may be formed into a foil-shaped preform by stretching the solder powder into a metal foil shape and then punching it out.
Furthermore, it is preferable that the temperature difference between the liquidus temperature and the solidus temperature is 60 ° C. or less.

  In order to confirm the effectiveness of the solder material of the present invention, the solidus temperature and the liquidus temperature were examined by changing various components and compositions of the alloy constituting the solder material. The solder material corresponding to the present invention is designated as Examples 1 to 28, and the solder material corresponding to the comparative example is designated as Comparative Examples 1 to 4.

[Example 1]
In the embodiment of the present invention, Sn is set to 28% by mass, Ag is set to 51.0% by mass, Sb is set to 17.0% by mass, Cu is set to 3.0% by mass, and In is set to 1.0% by mass. The solder material was manufactured by the manufacturing method described above.
[Examples 2-28]
A solder material was manufactured in the same manner as in Example 1 except that the composition ratio of the solder material was set as shown in Table 1 described later.
[Comparative Example 1]
Other than not using In and adding 0.02% each of Si and Ti as additives to the solder material and setting the composition ratio of Sn, Ag, Sb and Cu as shown in Table 1 below Produced a solder material in the same manner as in Example 1.
[Comparative Examples 2 and 3]
A solder material was manufactured in the same manner as in Example 1 except that In was not used and the composition ratio of Sn, Ag, Sb, and Cu was set as shown in Table 1 described later.
[Comparative Example 4]
A solder material was manufactured in the same manner as in Example 1 except that the composition ratio of Sn, Ag, Sb, Cu, and In was set as shown in Table 1 described later.

  For each of the solder materials manufactured as described above, the melting temperature range was measured based on JIS Z 3198-1, and the liquidus temperature and the solidus temperature were specified. The melting temperature range was measured by obtaining a differential scanning calorimetry curve using a differential scanning calorimeter Thermo plus EVO II / DSC8230 (manufactured by Rigaku).

1 and 2 show differential scanning calorimetry curves at various temperatures of the solder materials of Example 14 and Example 9, respectively. 1 and 2 show differential scanning calorimetry curves when the temperature is increased from room temperature (about 20 ° C.) to 450 ° C. at a rate of 10 ° C./min.
In the examples of FIGS. 1 and 2, since melting occurred suddenly, the tangent drawn at the point where the slope of the low-temperature curve of the straight line extending from the low-temperature base line to the high-temperature side and the low-temperature curve of the melting peak is maximized. The temperature at the point of intersection with was the solidus temperature.
In addition, the differential scanning calorimetry curves were respectively increased by increasing the temperature at a rate of 0.5 ° C / min, 1.0 ° C / min, 2.0 ° C / min, 5.0 ° C / min, 10.0 ° C / min. In each differential scanning calorimetry curve, extrapolation is the temperature at the intersection of the straight line obtained by extending the high-temperature base line to the low-temperature side and the tangent line drawn at the point where the slope of the high-temperature curve of the melting peak is maximum. The melting end temperature was determined, the relationship between the extrapolated melting end temperature and the square root of the heating rate in each differential scanning calorimetry curve was determined by a linear function, and the temperature axis intercept was taken as the liquidus temperature.

  As shown in FIG. 1, in the solder material of Example 14, the temperature drop start temperature is about 302 ° C., and the three peak tops (a) to (c) appearing in the differential scanning calorimetry curve are (a) 306 ° C., respectively. (B) Endothermic reactions were observed at 325 ° C. and (c) 331 ° C. In the solder material of Example 14, the solidus temperature was 303 ° C.

In the solder material of Example 9 shown in FIG. 2, the temperature drop start temperature is about 302 ° C., and the three peak tops (a) to (c) appearing in the differential scanning calorimetry curve are (a) 307 ° C. ( b) Endothermic reactions of 327 ° C. and (c) 342 ° C. were observed. In the solder material of Example 9, the solidus temperature was 301.5 ° C.
(Table 1)

According to this result, the liquidus temperature was higher than the solidus temperature in both Examples and Comparative Examples, but in Comparative Examples 1 to 3, the liquidus temperature was high and greatly exceeded 400 ° C. .
On the other hand, in Examples 1-28, solidus temperature was contained in the range of 284-340.6 degreeC, and liquidus temperature was 302-350 degreeC.

The liquidus temperature is lowered by adding 1.0% by mass or more of In to the solder material. However, if Sb is contained by 18.0% by mass or more, the error of the liquidus temperature becomes large. In addition, when the solder material contains more than 9.0% by mass of In and more than 32.0% by mass of Sn, the solidus temperature is lowered. According to this result, the solder material according to the embodiment of the present invention has a low liquidus temperature of 350 ° C. and a high solidus temperature of 280 ° C. or higher. Furthermore, paying attention to Comparative Example 23, by adding a little more In (as much as 0.5 mass%) than in Example 28, the solidus temperature rapidly decreases to around 220 ° C. Therefore, it can be understood from Table 1 that the solidus temperature can be set to a temperature exceeding 260 ° C. by adjusting the In composition ratio to be slightly higher than 9.0%.
In addition, the solidus temperature of Zn-Al alloy, Zn-Al-Mg alloy, and Bi-Ag alloy that are conventionally known are, for example, around 380 ° C, around 340 ° C, and around 260 ° C. There is a problem that it is difficult to use as a solder material because it matches the liquidus temperature.

Claims (6)

Made of at least a quinary alloy containing Sn, Ag, Cu, Sb and In,
A solder material characterized in that a solidus temperature is higher than 260 ° C., a liquidus temperature is 350 ° C. or lower, and a liquidus temperature is higher than a solidus temperature.   Sn is 32 mass% or less, Sb is 10 to 17 mass%, Cu is 1 to 4 mass%, In is less than 1 to 9.5 mass%, and the balance contains Ag and inevitable impurities. The solder material according to 1.   The solder material according to claim 1 or 2, wherein a temperature difference between the liquidus temperature and the solidus temperature is within 60 ° C.   The solder material according to any one of claims 1 to 3, wherein the solidus temperature is 280 ° C or higher.   The solder material according to any one of claims 1 to 4, wherein the solder material is in a paste form mixed with a flux.   5. The solder material according to claim 1, wherein the solder material is a preform that has been punched after being processed into a metal foil shape. 6.

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