KR20170130757A - Lead free solder composition with high ductility - Google Patents

Abstract

Disclosed is a lead-free solder composition, comprising: 0.02-6 wt% of stibium; 0.03-3 wt% of copper; 0.03-8 wt% of bismuth; 55-75 wt% of indium; 0.3-8 wt% of silver; 5-11 wt% of magnesium; 0.2-1.65 wt% of scandium; 0.2-2.4 wt% of ruthenium; and 10-45 wt% of tin. The lead-free solder composition of the present invention is suitable for soldering an electrical connection portion on a metalized surface of a glass because the lead-free solder composition has a solid-state temperature at 120C or higher, excellent ductility, and stability.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lead free solder composition,

The present invention relates to a lead-free solder composition, specifically a high ductility lead-free solder composition.

Generally, a rear window of an automobile is provided with an electric device such as a defrosting device arranged on a glass. In order to provide an electrical connection to an electrical device, a metal coating, usually of small area, is applied to the glass to obtain a metallized surface that is configured to be electrically connected to the electrical device, on which the electrical connection of the electrical device is soldered .

In the prior art, electrical connections are soldered onto the metallized surface of the window glass with lead (Pb) -containing solder. However, due to environmental pollution caused by lead, the use of lead is more restricted, and lead-free solder is beginning to be used in soldering applications. For example, conventional lead-free solders having a tin (Sn) content as high as 80% or more are used in some industries.

However, glass is fragile and can lead to glass cracks when soldering electrical devices to glass with conventional tin-free, lead-free solders. In addition, soldering two materials (e.g., glass and copper) having different thermal expansion coefficients may stress the solder during cooling of the solder joint or during subsequent temperature excursions. On the other hand, a solder composition suitable for soldering an electrical device to glass should have a melting point (i.e., liquidus temperature) low enough to prevent cracking of the automotive glass in the soldering process, which results in a higher melting point and corresponding higher process temperature Because the thermal expansion coefficient increases the adverse effect of mismatching, so that a higher stress is applied to the solder during cooling. Therefore, the solder must have excellent ductility. On the other hand, the melting point of the solder composition must be sufficiently high such that the solder does not melt during normal use of the vehicle, such as when the vehicle is exposed to sunlight with the windows closed and under very harsh environmental conditions.

The conventional lead-free solder composition that has been already disclosed contains indium (In) of 64.35 to 65.65 wt%, tin (Sn) of 29.7 to 30.3 wt%, silver (Ag) of 4.05 to 4.95 wt%, and copper Cu) (hereinafter, this solder is referred to as "65 indium solder").

However, indium-containing solders usually have a much lower melting point than other solders. For example, for solid state temperatures, lead solder is 160 ° C versus 65 ° indium solder is 109 ° C. For liquid temperatures, lead solder is 224 ° C versus 65 ° indium solder is 127 ° C. Generally, the higher indium content of the solder degrades the solidus temperature of the solder. According to some vehicle manufacturers, the solder joints must be able to withstand the elevated temperatures, so the indium containing solder should have good ductility at temperatures of -40 ° C to 120 ° C and solid-state temperatures of at least 120 ° C without any further degradation.

Also, when soldering multiple closely spaced electrical connections, the soldering of the electrical connections affects adjacent soldered electrical connections, so the solder must be highly stable and ductile. Otherwise, adjacent electrical connections are likely to melt again and crack.

Accordingly, it is an object of the present invention to provide a process for the production of silver, which comprises 0.02 to 6% by weight of stibing, 0.03 to 3% by weight of copper, 0.03 to 8% by weight of bismuth, 55 to 75% by weight of indium, 0.3 to 8% Lead-free solder composition comprising from about 10 to about 11 weight percent magnesium, from about 0.2 to about 1.65 weight percent scandium, from 0.2 to 2.4 weight percent ruthenium, and from 10 to 45 weight percent tin.

Preferably, the lead-free solder composition may comprise 1.2 to 1.4% by weight of scandium.

Preferably, the lead-free solder composition may comprise from 1.0 to 1.1 wt% ruthenium.

The lead-free solder composition may have a solidus temperature in the range of 120 to 135 占 폚.

In addition, the solder composition may have a liquidus temperature ranging from 130 to 145 占 폚.

Preferably, the lead-free solder composition may comprise 3 to 4% by weight of stibing.

Preferably, the lead-free solder composition may comprise from 4 to 5% by weight of bismuth.

The lead-free solder composition of the present invention is suitable for soldering electrical connections on a metallized surface of glass with a solid-state temperature of 120 ° C or higher and excellent ductility and stability.

The present disclosure will be described in detail below in conjunction with some embodiments. It should be understood that the specific embodiments described herein are not intended to limit the invention, but merely illustrate the invention.

The present disclosure provides lead-free solder compositions suitable for soldering electrical components to glass. Illustratively, such soldering is required in the manufacture of the rear window of an automobile, which includes a window defroster, which is comprised of an electrically resistive defrost line embedded in the inner surface of the rear window or deposited on the inner surface. The thawing line is electrically connected to a pair of electrical contact strips (e.g., battery contact surfaces called bus bars) positioned on the inner surface of the rear window. The electrical contact strip may comprise a conductive coating deposited on the inner surface of the rear window. Typically, the electrical contact strip is formed of a silver-containing material.

In order to overcome the problems of the prior art, according to an embodiment of the present invention, there is provided a method of manufacturing a semiconductor device comprising: 0.02 to 6 wt% of stibing, 0.03 to 3 wt% of copper, 0.03 to 8 wt% of bismuth, 55 to 75 wt% There is provided a lead-free solder composition comprising 0.3 to 8 wt% silver, 5 to 11 wt% magnesium, 0.2 to 1.65 wt% scandium, 0.2 to 2.4 wt% ruthenium, and 10 to 45 wt% tin.

In one embodiment, the lead-free solder composition comprises scandium and ruthenium, wherein scandium is effective at reducing particle size and is characterized by an increase in recrystallization temperature, improved stability and ductility of the solder, and ruthenium has a high melting point, And high corrosion resistance, which improves the strength, heat resistance and corrosion resistance of the solder and prevents cracking of the solder joint, raises the solid phase temperature of the solder composition to a range of from 120 to 135 占 폚, and the liquidus temperature of the solder composition is from 130 to 145 ≪ / RTI >

In some embodiments, the lead-free solder composition may comprise 1.2 to 1.4 wt%, more preferably 1.3 wt%, of scandium.

In some embodiments, the lead-free solder composition may comprise 1.0 to 1.1 wt%, more preferably 1.05 wt% ruthenium.

In some embodiments, the lead-free solder composition may comprise 3 to 4 wt% stibium and 4 to 5 wt% bismuth.

In some embodiments, the lead-free solder composition may comprise 6 to 10 wt%, preferably 7 to 9 wt%, more preferably 8 wt% magnesium. In some embodiments, the lead-free solder composition may comprise 8 to 9 weight percent magnesium.

As described above, the lead-free solder composition of the present invention has a solid-state temperature ranging from 120 to 135 占 폚 and a liquidus temperature ranging from 130 to 145 占 폚. Specifically, the solid phase temperature is defined as the temperature at which the alloy begins to melt. Below the solid phase temperature, the material is a complete solid phase with no molten phase. The liquidus temperature is the maximum temperature at which crystals (unmelted metal or alloy) can coexist with the melt. Above the liquid temperature, the material is a homogeneous phase consisting solely of molten metal. The solder processing temperature is higher than the liquid temperature by the temperature value determined by the soldering technique.

The solder composition of the present invention does not contain lead and has a higher working temperature than other solders of the same type, typically about 105 ° C. In addition, the solder composition of the present invention is far superior in ductility and stability to lead-free solder compositions of the prior art.

The combination of bismuth and copper and other elements improves the overall performance of the solder composition, including increased expectations of the operating temperature of the solder and improved mechanical performance of the solder under certain conditions.

In some embodiments, the lead-free solder composition may have a solidus temperature in the range of 120 to 135 占 폚.

Also in some embodiments, the lead-free solder composition may have a liquidus temperature in the range of 130 to 145 占 폚.

In some embodiments, the lead-free solder composition may comprise 3 to 4 weight percent stibb.

In some embodiments, the lead-free solder composition may comprise from 4 to 5% by weight of bismuth.

The lead-free solder composition of the present invention is suitable for soldering electrical connections on a metallized surface of glass with a solid-state temperature of 120 ° C or higher and excellent ductility and stability.

Now, the crack preventing performance of the solder joint formed by the lead-free solder composition of the present invention is shown in Table 1 below by comparing Examples and Comparative Examples of the present invention.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Content (% by weight) Stibium One 2.3 4 4.3 5 4 5 Copper 0.1 0.5 One 1.4 2 One 2 Bismuth 0.5 1.5 3 5 7 3 5 indium 55 60 65 70 75 50 60 silver 0.5 1.5 2.5 4 6 2.5 4 magnesium 5 7 8 9 10 8 9 scandium 0.2 0.6 1.1 1.4 1.65 0.05 1.8 ruthenium 0.2 0.9 1.6 2.0 2.4 0.05 2.9 Remark 10 20 25 30 40 30 40 crack v v v v v x x ductility Good Good Good Good Good Bad Bad

week:

√: No cracks in adjacent solder joints during soldering

X: Cracking of adjacent solder joints during soldering

As can be seen from the above table, when the amount of scandium contained in the solder composition is in the range of 0.2 to 1.65 wt%, the solder joint formed of the lead-free solder composition of the present invention may not crack in the subsequent process. However, if the amount of scandium contained in the solder composition is less than 0.2 wt% or exceeds 1.65 wt%, the anti-cracking performance of the solder is deteriorated. Further, when the amount of ruthenium contained in the solder composition is in the range of 0.2 to 2.4 wt%, the solder joint formed by the lead-free solder composition of the present invention has excellent ductility. However, if the amount of ruthenium contained in the solder composition is less than 0.2 wt% or exceeds 2.4 wt%, the softening performance of the solder is deteriorated.

High temperature storage test

The ductile performance of the lead-free solder according to an embodiment of the present invention is tested by a high temperature storage test. In this test, the temperature of the climate-controlled chamber was kept constant at 120 ° C, and the electrical connection and the metallization surface soldered by the solder of this invention to the electrical connection were placed in a temperature controlled test chamber, Newton's weights were suspended for 24 hours at the electrical connections. After 24 hours elapsed, the electrical connection was pulled out (at ambient temperature) with a force of 50 N by a digital meter for 3 seconds. As a result, cracking of the electrical connections did not occur during this test.

As is known, preferred embodiments of the present invention and related technical principles are only as described above. It should be understood by those skilled in the art that the present disclosure is not limited to the specific embodiments described herein. It will be apparent to those skilled in the art that various modifications, alterations, and alternatives are possible without departing from the scope of protection of the present invention. Therefore, although the present disclosure is described in detail by way of the above embodiments, it is not limited to the above embodiments, and may include other equivalent embodiments without departing from the concept of the present disclosure. The scope of the present disclosure falls within the scope of the appended claims.

Claims (5)

A lead-free solder composition comprising:
0.02 to 6% by weight of stibium,
0.03 to 3% by weight of copper,
0.03 to 8% by weight of bismuth,
55 to 75% by weight of indium,
0.3 to 8% by weight of silver,
5 to 11% by weight of magnesium,
0.2 to 1.65% by weight of scandium,
0.2 to 2.4 wt% ruthenium, and
10 to 45% by weight of tin
≪ / RTI > The lead-free solder composition of claim 1 comprising 1.2 to 1.4 wt% of scandium. The lead-free solder composition of claim 1, comprising from 1.0 to 1.1 percent by weight of ruthenium. The lead-free solder composition according to claim 1, wherein the solid-phase temperature of the lead-free solder composition is 120 to 135 占 폚. The lead-free solder composition according to claim 3, wherein the liquidus temperature of the lead-free solder composition is 130 to 145 占 폚.