KR20170108743A - Lead free solder composition with high ductility - Google Patents

Abstract

According to an embodiment of the present invention, provided is a lead-free solder composition which comprises: 0.02-6 wt% of stibium; 0.03-3 wt% of copper; 0.03-8 wt% of bismuth; 55-68 wt% of indium; 0.3-8 wt% of silver; 5-11 wt% of magnesium; 0.3-1.45 wt% of scandium; 0.6-1.8 wt% of cerium; and 10-45 wt% of tin. According to the present invention, a solidus line temperature of the lead-free solder composition is not less than 120C, and has excellent ductility and stability to be suitable to solder an electric connector on a metal surface on glass.

Description

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

The present invention relates to a lead-free solder composition, and more particularly to a lead-free solder composition having high ductility.

BACKGROUND OF THE INVENTION [0002] A rear window of an automobile includes an electrical device, such as a defroster, generally located on a glass. In order to provide an electrical connection to the electrical device, a small metal coated area is usually applied to the glass to obtain a metal surface for electrical connection with the electrical device. The electrical connector of the electrical device may also be soldered to a metal surface.

Conventional electrical connectors are soldered onto a glass surface by a solder containing lead (Pb) on a metal surface. However, due to environmental pollution caused by lead, the use of lead is becoming increasingly limited, and for this reason lead-free solders that do not contain lead in the soldering process have begun to be used. For example, lead-free solders having a high tin (Sn) content of 80% or more are generally used in some industries.

However, glass is fragile and conventional lead-free solders with high tin content tend to cause cracking of the glass in the process of soldering electrical devices on the glass. Moreover, when soldering two materials (e.g., glass and copper) that have significantly different coefficients of thermal expansion (CTE), stress is applied to the solder due to cooling of the solder joints or subsequent temperature drift. Therefore, solder compositions suitable for electrical devices soldered on glass, on the one hand, have a high melting point of the solder composition and correspondingly high process temperatures, which increase the coefficient of thermal expansion mismatch and can place high stresses on the solder during the cooling process , A melting point (in other words, a liquidus temperature) that is low enough not to cause cracking of the glass during the soldering process. As a result, the solder needs further to have good ductility.

On the other hand, the melting point of the solder composition is required to be sufficiently high such that the automobile is in the sun when the window is closed, or is insoluble during normal use of the vehicle, such as in extreme harsh environmental conditions.

(Ag), and 0.25% -0.75% copper (Cu) as the prior art, which is an alloy containing 64.35% -65.65% indium (In), 29.7% -30.3% tin (Sn), 4.05% -4.95% Solder compositions are known. (Hereinafter referred to as " 65 indium solder "),

However, indium-containing solders generally have a melting point that is too low compared to other solders. For example, the solidus temperature of the lead solder is 160 ° C, while the lead temperature of the 65-indium solder is 109 ° C, while the liquidus temperature of the lead solder is 224 ° C. The line temperature is 127 ° C. Generally, the high indium content of the solder leads to a low solidus temperature of the solder. Some automobile manufacturers require solder joints to be maintained at high temperatures, so that indium-containing solders must have a ductility lower than 120 占 폚 and excellent ductility without deterioration of performance at -40 占 폚 to 120 占 폚.

Moreover, the soldering of the plurality of electrical connectors is arranged so close that the soldering of the electrical connector can affect other electrical connectors that are soldered adjacent to each other, and for that reason, the high stability and ductility of the solder is essential. Otherwise, the solder of the adjacent electrical connector may melt again or crack.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lead-free solder composition having excellent ductility and stability, which is suitable for soldering an electrical connector to a metal surface on a glass.

According to an embodiment of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: 0.02 wt% to 6 wt% stibium; 0.03 wt% to 3 wt% copper; 0.03 wt% to 8 wt% (bismuth), 55 to 68 wt% indium, 0.3 wt% to 8 wt% silver, 5 wt% to 11 wt% magnesium, 0.3 wt% to 1.45 wt% Lead free solder composition comprising scandium, from 0.6 wt% to 1.8 wt% cerium, and from 10 wt% to 45 wt% tin.

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

Preferably, the lead-free solder composition may comprise from 0.7% to 0.8% by weight of cerium.

The lead-free solder composition may have a solidus temperature of 120 < 0 > C to 135 < 0 > C.

Further, the lead-free solder composition may have a liquidus temperature of 130 캜 to 145 캜.

Preferably, the lead-free solder composition may comprise 3 wt% to 4 wt% antimony.

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

The lead-free solder composition of the present invention is suitable for soldering an electrical connector to a metal surface on a glass because the solidus temperature is not lower than 120 占 폚 and has excellent ductility and stability.

The present invention will be described in more detail with reference to some embodiments described below. The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these embodiments.

The present invention provides lead-free solder suitable for soldering electrical components on glass. For example, such soldering is required to manufacture a rear window of a vehicle that includes a window defroster in the form of an electrical resistance defrost line embedded or deposited on the inner surface of the rear window. The defrost line is electrically connected to a pair of electrical contact strips (also referred to as electrical contact surfaces, buss bars) located on the inner side of the rear window. The electrical contact strip may be made of a conductive coating on the inner surface of the rear window. Generally, the electrical contact strip is formed of a material comprising silver.

In order to overcome the problems of the prior art, an embodiment of the present invention is directed to a method of manufacturing a semiconductor device comprising 0.02 wt% to 6 wt% stubium, 0.03 wt% to 3 wt% copper, 0.03 wt% to 8 wt% (bismuth), 55 to 68 wt% indium, 0.3 wt% to 8 wt% silver, 5 wt% to 11 wt% magnesium, 0.3 wt% to 1.45 wt% Lead scandium, from 0.6 to 1.8 weight percent cerium, and from 10 to 45 weight percent tin.

In this embodiment, the lead-free solder composition comprises scandium and cerium. Scandium has the effect of reducing the grain size and raising the recrystallization temperature to increase the ductility and stability of the solder. Since cerium has a high melting point, high strength and strong corrosion resistance, the strength, heat resistance and corrosion resistance of the solder are improved to prevent cracking of the solder joint, and the solidus temperature of the solder composition is set to 120 to 135 DEG C, Lt; 0 > C to 145 < 0 > C.

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

In some embodiments, the lead-free solder composition may comprise from 0.7 wt% to 0.8 wt%, more preferably 0.75 wt% of cerium.

In some embodiments, the lead (Pb) -free solder composition may include 3 wt% to 4 wt% antimony and 4 wt% to 5 wt% bismuth.

In some embodiments, the lead-free solder composition may comprise from 6 wt% to 10 wt%, preferably 7 wt% to 9 wt%, more preferably 8 wt% magnesium. In yet another embodiment, the lead-free solder composition can comprise from 8 wt% to 9 wt% magnesium.

As described above, the lead-free solder composition of the present invention has a solidus temperature of 120 캜 to 135 캜 and a liquidus temperature of 130 캜 to 145 캜. The solidus temperature is effectively defined as the temperature at which the alloy begins to melt. At temperatures below the solidus temperature, the material is a complete solid without melt phase material. The liquidus temperature is the highest temperature that can coexist with the melt phase of the crystal (insoluble metal or alloy). At temperatures above the liquidus temperature, only molten phase materials are present. The solder process temperature is determined by the soldering technique and is higher than the liquidus temperature.

The solder composition of the present invention does not contain lead and has a higher working temperature than other solders, generally about 105 캜. In addition, the solder composition of the present invention has better ductility and stability as compared to conventional lead-free solder compositions.

The combination of bismuth and copper with other components can improve the overall performance of the solder composition, including expected solder operating temperature rise and mechanical performance in certain states.

In some embodiments, the lead-free solder composition may have a solidus temperature of 120 < 0 > C to 135 < 0 > C.

Further, in some embodiments, the solder composition may have a liquidus temperature of from 130 캜 to 145 캜.

In some embodiments, the lead-free solder composition may comprise from 3 wt% to 4 wt% antimony.

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

The lead wire temperature of the lead-free solder composition of the present invention is not lower than 120 占 폚, and has excellent ductility and stability, and is therefore suitable for soldering an electrical connector to a metal surface on a glass.

Now, as shown in the following Table 1, crack prevention performance of a solder joint formed of lead-free solder according to the present invention will be described through comparison of Examples and some comparative examples.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Content (% by weight) antimony 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 57 60 65 68 57 60 silver 0.5 1.5 2.5 4 6 2.5 4 magnesium 5 7 8 9 10 8 9 scandium 0.3 0.6 1.1 1.2 1.45 0.2 1.8 cerium 0.6 0.6 1.0 1.2 1.8 0.05 2.0 Remark 10 20 25 30 40 30 40 Crack occurrence v v v v v x x ductility Good Good Good Good Good Poor Poor

In Table 1, v indicates that no cracks occurred in adjacent solder joints during soldering, and x indicates that cracks occurred in adjacent solder joints during soldering.

As can be seen from the above table, when the lead-free solder of the present invention contains 0.3 wt% to 1.45 wt% of scandium in the solder composition, it is possible to avoid occurrence of cracks in the solder joint in the subsequent process. However, it was confirmed that the solder composition containing less than 0.3% by weight of scandium or containing more than 1.45% by weight of scandium had a deteriorated cracking performance of the solder. In addition, when the lead-free solder of the present invention contains 0.6 wt% to 1.8 wt% of cerium in the solder composition, it is confirmed that the lead-free solder has excellent ductility. However, it was confirmed that the ductility of the solder was lowered in the case of the solder composition containing less than 0.6 wt% of cerium or more than 1.8 wt% of cerium.

High temperature storage test

The ductility was tested through a high temperature storage test of lead-free solder according to an embodiment of the present invention. In the test, the electrical connector with the electrical connector brazed by the solder of the present invention and the metal surface were placed in the climate control chamber, and while the climate control chamber was maintained at a temperature of 120 ° C for 24 hours, I have. After 24 hours, the electrical connector was pulled for 3 seconds at ambient temperature with a force of 50 N of Digital force gauge, but no break due to cracks in the electrical connector occurred during the test.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (5)

0.02% to 6% by weight of stubium,
0.03% to 3% by weight of copper,
0.03 wt% to 8 wt% bismuth,
55% to 68% by weight of indium,
0.3% to 8% by weight of silver,
5% to 11% by weight of magnesium,
0.3% by weight to 1.45% by weight of scandium,
From 0.6% to 1.8% by weight of cerium, and
A lead-free solder composition comprising 10 wt% to 45 wt% tin. The method of claim 1,
And the scandium comprises from 1.0 wt% to 1.1 wt%. The method of claim 1,
And the cerium comprises 0.7 wt% to 0.8 wt%. The method of claim 1,
Wherein the solidus temperature of the lead-free solder composition is between 120 < 0 > C and 135 < 0 > C. 4. The method of claim 3,
Wherein the liquidus temperature of the lead-free solder composition is 130 占 폚 to 145 占 폚.