KR20180012082A - Lead free solder composition with high ductility - Google Patents

Abstract

Disclosed is a lead-free solder composition, which comprises: 0.02-6 wt% of antimony; 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; 0.2-1.55 wt% of scandium; 0.2-2.0 wt% osmium; and 10-45 wt% of tin. According to the present invention, the lead-free solder composition has the solidus temperature of at least 120 °C and secures ductility and safety at a good quality. Therefore, the present invention is suitable for soldering an electric connector on a metallized surface on a glass phase.

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 lead-free solder compositions, and particularly lead-free solder compositions with high ductility.

BACKGROUND OF THE INVENTION Automotive rear windows typically include electrical devices such as defrosters located on glass. To provide an electrical connection to an electrical device, a small area of metallic coating is generally applied to the glass to obtain a metallized surface that is configured to be electrically connected to the electrical device, and then the electrical connector of the electrical device is soldered onto the metallized surface can do.

In the prior art, electrical connectors are soldered onto a metallized surface on glass with solder containing lead (Pb). However, due to environmental pollution caused by lead, lead-free solders are beginning to be used in soldering applications, as the use of lead is increasingly limited. For example, in some industries conventional lead-free solders are employed that contain a high tin (Sn) content, such as greater than 80%.

However, since glass is brittle, conventional lead-free solders with high tin content tend to cause cracking of the glass during soldering of electrical devices on glass. Further, the step of soldering two materials (e.g., glass and copper) having substantially different coefficients of thermal expansion (CTE) may be performed during cooling of the solder joint, or during subsequent temperature excursion, Stresses on the solder. On the one hand, therefore, a solder composition suitable for soldering an electrical device on glass, because a higher melting point and correspondingly higher processing temperature amplifies the adverse effects of CTE mismatch and imposes a higher stress on the solder during cooling It is necessary to have a sufficiently low melting point (i.e., liquidus temperature) so as not to cause cracking of the automobile glass during the soldering process. As a result, it is further required that the solder has good ductility. On the other hand, the melting point of the solder composition needs to be high enough so that the solder does not melt during normal use of the vehicle, such as when the car is in a sunny location or under extreme harsh environmental conditions.

Lead solder composition having a weight percentage of 64.35% -65.65% indium (In), 29.7% -30.3% tin (Sn), 4.05% -4.95% silver (Ag), and 0.25% -0.75% copper Referred to as "65 indium solder") have been conventionally disclosed.

However, indium containing solders usually have much lower melting points than other solders. For example, a 65 indium solder has a solidus temperature of 109 占 폚 as compared to 160 占 폚 of a lead solder and a liquidus temperature of 127 占 폚 as compared to 224 占 폚 of the solder. Generally, the higher indium content in the solder causes the lower solid-state temperature of the solder. Some vehicle manufacturers want the solder joints to withstand the temperature rise so that indium-containing solders should have a solid-state temperature above 120 ° C without any performance degradation, and should have good ductility over a temperature range of -40 ° C to 120 ° C do.

In addition, in soldering a plurality of closely spaced electrical connectors, the solder must have high stability and ductility, since the soldering of one electrical connector will affect the adjacent soldered electrical connector, otherwise the solder of the adjacent electrical connector The possibility of re-melting and cracking will be high.

Accordingly, it is an object of the present invention to provide a process for the preparation of antimony, comprising 0.02 wt% to 6 wt% antimony, 0.03 wt% to 3 wt% copper, 0.03 wt% to 8 wt% bismuth, 55 wt% to 75 wt% To 8% silver, 5% to 11% magnesium, 0.2% to 1.55% scandium, 0.2% to 2.0% osmium, and 10% to 45% Lead-free solder composition.

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

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

The solid phase temperature of the lead-free solder composition may range from 120 占 폚 to 135 占 폚.

In addition, the liquidus temperature of the solder composition may range from 130 캜 to 145 캜.

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

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 has a solid-state temperature of 120 ° C or higher, has good ductility and stability, and is therefore suitable for soldering electrical connectors on a metallized surface on glass.

The invention will be further illustrated in further detail below with some embodiments. It is to be understood that the particular embodiments described herein are not intended to limit the invention, but merely to illustrate the invention.

The present invention provides lead-free solder compositions suitable for soldering electrical components on glass. Illustratively, such soldering is required for the manufacture of automotive rear window including a window defroster composed of an electrically resistive defrost line embedded within or deposited on the inside surface of the rear window. The defrost line is electrically connected to a pair of electrical contact strips (i.e., electrical contact surfaces, also referred to as bus bars) located on the inner surface of the rear window. The electrical contact strip may be comprised of a conductive coating deposited on the inner surface of the rear window. Typically, the electrical contact strip is formed from a silver-containing material.

In order to overcome the problems of the prior art, embodiments of the present invention may comprise 0.02 wt% to 6 wt% antimony, 0.03 wt% to 3 wt% copper, 0.03 wt% to 8 wt% bismuth, 55 wt% Magnesium, 0.2 to 1.55 wt.% Scandium, 0.2 wt.% To 2.0 wt.% Osmium, and 10 wt.% To 20 wt.% Indium, 0.3 wt.% To 8 wt.% Silver, 5 wt.% To 11 wt.% Magnesium, Lead-free solder composition comprising 45 wt% tin.

In an embodiment, the lead-free solder composition comprises scandium and osmium, wherein scandium has the effect of reducing the grain size and raising the recrystallization temperature and improving the ductility and stability of the solder, while the osmium has a high High temperature strength, and corrosion resistance, can prevent cracking of the solder joint, and can prevent the solid phase temperature of the solder composition from being raised to a temperature of from 120 캜 to 135 캜 And the liquidus temperature of the solder composition is increased to within the range of 130 캜 to 145 캜.

In some embodiments, the lead (Pb) -free solder composition may comprise 1.2 wt.% To 1.4 wt.%, More preferably 1.3 wt.% Scandium.

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

In some embodiments, the lead (Pb) -free solder composition may comprise 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 some other embodiments, the lead-free solder composition may comprise from 8 wt% to 9 wt% magnesium.

As noted above, lead-free solder compositions of the present invention have a solidus temperature in the range of 120 캜 to 135 캜 and a liquidus temperature in the range of 130 캜 to 145 캜. The solid phase temperature is effectively defined as the temperature at which the alloy begins to melt. Below the solidus temperature, the material is completely solid and there is no molten phase. The liquidus temperature is the maximum temperature at which crystals (unmelted metal or alloy) can coexist with the melt. If the liquid temperature is exceeded, the material is homogeneous and consists only of the melt. The solder processing temperature is higher than the liquid temperature by the frequency determined by the soldering technique.

The solder composition of the present invention has no lead and has a working temperature higher than the working temperature of other solders of the same type, typically about 105 ° C. In addition, the solder composition of the present invention has much better ductility and stability as compared to prior art 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 an expected increase in the operating temperature of the solder and an improvement in the mechanical performance of the solder under certain conditions.

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

In some further embodiments, the liquidus temperature of the solder composition may range 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% bismuth.

The lead-free solder composition of the present invention is suitable for soldering an electrical connector on a metallized surface on a glass, since the solidus temperature is not less than 120 캜 and has good ductility and stability.

With reference now to a comparison between embodiments of the present invention and some comparative examples, the crack-preventing performance of solder joints formed by lead-free solder compositions of the present invention, as shown in Table 1 below, will be described.

Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Comparative Example 1 Comparative Example 2


content
(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 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 1.55 0.05 1.8 osmium 0.2 0.9 1.6 1.8 2.0 0.05 2.9 Remark 10 20 25 30 40 30 40 crack √ √ √ √ √    ×    × ductility Good Good Good Good Good Bad Bad

week:

√: No cracks in adjacent solder joints during soldering

X: Cracks occur in adjacent solder joints during soldering

As can be seen from the above table, cracking of the solder joint formed by the lead-free solder composition of the present invention can be prevented in subsequent processes when scandium is contained in the solder composition in an amount ranging from 0.2 wt% to 1.55 wt% . However, when scandium is contained in an amount of less than 0.2 wt% or more than 1.55 wt% in the solder composition, the crack-preventing performance of the solder is deteriorated. Additionally, when the amount of osmium in the solder composition is in the range of 0.2 wt% to 2.0 wt%, the solder joint formed by the lead-free solder composition of the present invention has good ductility. However, when the content of osmium in the solder composition is less than 0.2 wt% or more than 2.0 wt%, the softening performance of the solder is lowered.

High temperature storage test

The high temperature storage test tests the ductile performance of lead-free solders of embodiments of the present invention. In this test, the temperature of the climate controlled chamber was maintained at a constant 120 ° C, the metallization surface, on which the electrical connector and the solder of the present invention were soldered onto it, was placed in the climate control chamber, From Newton for 24 hours. After the end of 24 hours, the electric coupler was pulled by a digital force gauge for 3 seconds with a force of 50 N (at ambient temperature) and no cracks were separated from the electrical coupler during this test.

It is noted that the preferred embodiments of the present invention and applied technical principles are described only as above. It should be understood by those skilled in the art that the present invention is not limited to the specific embodiments described herein. Those skilled in the art will be able to make various obvious changes, readjustments, and alternatives without departing from the scope of protection of the present invention. Therefore, while the present invention is illustrated in detail by the foregoing embodiments, the present invention is not limited to only those embodiments, and may further include many other equivalent embodiments without departing from the spirit of the present invention . The scope of the invention is in accordance with the appended claims.

Claims (5)

0.02% to 6% by weight of antimony,
0.03% to 3% 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% magnesium,
0.2% to 1.55% by weight of scandium,
0.2% to 2.0% by weight osmium, and
A lead free solder composition comprising 10 wt% to 45 wt% tin. The method according to claim 1,
1. A lead-free solder composition comprising 1.2 wt% to 1.4 wt% scandium. The method according to claim 1,
1. A lead-free solder composition comprising 1.0 wt% to 1.1 wt% osmium. The method according to claim 1,
Wherein the solidus temperature is in the range of 120 < 0 > C to 135 < 0 > C. The method of claim 3,
Wherein the liquidus temperature is in the range of 130 占 폚 to 145 占 폚.