Lead-free solder based on indium-tin-silver

Abstract

Described herein are indium-tin-silver alloys suitable for use as lead-free solders. The alloys can comprise indium primarily or tin primarily. The alloys can further comprise copper, nickel, and iron or copper, antimony, and zinc. The compositions can be used to solder electrical connectors (18, 30) to electrical contact surfaces (16) on glass assemblies (10). Also described herein are methods of forming the alloys.

Description

[0001] This application is a divisional application filed again with respect to divisional application 202211008509.1. Divisional application 202211008509.1 is a divisional application filed with respect to divisional application 202110190195.0, which is a divisional application of the invention patent application entitled "Lead-free solder based on indium-tin-silver" with PCT international application number PCT / US2016 / 032076, international application date of 2016-05-12, application number 201680028036.8 that entered the Chinese national phase. Technical Field

[0002] This invention relates to a solder, particularly a lead-free solder based on indium-tin-silver. Background Technology

[0003] Windshields and rear windows of vehicles (such as automobiles) often include electrical devices located within or on the glass. These devices are typically antennas or defrosters. To provide an electrical connection to these devices, a small area of ​​metallic coating is applied to the glass to create a metallized surface for electrical connection. An electrical connector, used to connect lead or lead itself, is then soldered to the metallized surface. The connector is typically soldered to the metallized surface of the glass using lead (Pb) solder. Due to environmental concerns and / or regulatory requirements in various countries, most industries now use or plan to use lead-free solder in soldering applications. Conventional lead-free solders used in some industries contain high tin (Sn) content, such as over 80%. Lead-free solder used on automotive glass, as described herein, is disclosed in U.S. Patent No. 6,253,988, issued July 3, 2001, to John Pereira (hereinafter referred to as “Pereira”). Among several lead-free solders, Pereira discloses solders with the following weight percentages: 64.35% to 65.65% indium (In), 29.7% to 30.3% tin (Sn), 4.05% to 4.95% silver (Ag), and 0.25% to 0.75% copper (Cu) (hereinafter referred to as "65 Indium Solder").

[0004] Soldering devices to automotive glass presents numerous challenges not encountered in other applications. Automotive glass tends to be brittle, and conventional high-tin lead-free solders used in other applications often cause it to crack. While materials such as ceramics and silicon may appear similar to automotive glass in some respects, solders partially suitable for soldering ceramic or silicon devices are not suitable for soldering automotive glass. The significantly different coefficients of thermal expansion (CTE) of the two materials (e.g., glass and copper in this application) impose stress on the solder during cooling after the weld joint is formed, or during subsequent temperature shifts. The solder needs to have a sufficiently low melting point (liquidline) to prevent cracking of the automotive glass during the soldering process, as a higher melting point and correspondingly higher processing temperature increase CTE mismatch and impose higher stress during cooling. However, the solder's melting point needs to be high enough so that it does not melt during normal use of the vehicle, such as when the vehicle is in direct sunlight with the windows closed, or under other extreme environmental conditions. However, indium-containing solders typically have melting points much lower than other solders. For example, compared to the solidus temperature of lead solder (160°C), the solidus temperature of 65In solder is 109°C, and compared to the liquidus temperature of lead solder (224°C), the liquidus temperature of 65In solder is 127°C. Some vehicle manufacturers expect their glass products to withstand elevated temperatures (e.g., 110°C for one manufacturer and 120°C for another) without any performance degradation.

[0005] Therefore, there is a need for lead-free solder suitable for use on glass, which can withstand higher elevated temperatures while providing all the other properties required for this application compared to currently available compositions.

[0006] The topics discussed in the background section are mentioned only within the background section and should not be assumed to be prior art. Similarly, the problems mentioned in the background section or related to the topics in the background section should not be assumed to have been known prior in the prior art. The topics in the background section merely represent different methods, which may themselves be inventions. Summary of the Invention

[0007] According to one embodiment of the invention, an indium-tin-silver based solder is provided. A first embodiment is an alloy suitable for use as a solder, the alloy having a mixture comprising: about 40 wt% tin, about 0.5 wt% copper, about 50 wt% indium; about 4.5 wt% silver, about 1.8 wt% to about 2.1 wt% nickel, and about 2.9 wt% to 3.2 wt% iron. The alloy may contain about 1.8 wt% nickel and about 3.2 wt% iron. Alternatively, the alloy may contain about 2.1 wt% nickel and about 2.9 wt% iron.

[0008] The second embodiment is an alloy suitable for use as a solder, the alloy having a mixture comprising: about 14% to about 15% tin, about 1% antimony, about 1% copper, about 5% to about 6% silver, about 1% to about 3% nickel, about 1% zinc, and about 75% indium. The alloy may contain about 14% tin, 5% silver, and about 3% nickel. Alternatively, the alloy may contain about 15% tin, 6% silver, and about 1% nickel.

[0009] The third embodiment is an alloy suitable for use as solder, the alloy having a mixture comprising about 75% by weight tin, about 5% by weight silver, and about 20% by weight indium.

[0010] The fourth embodiment is an alloy suitable for use as solder, the alloy having a mixture comprising about 7% by weight tin, about 3% by weight silver, and about 90% by weight indium.

[0011] According to another embodiment of the invention, an electrical connection on a glass assembly is provided. A fifth embodiment is an electrical connection on a glass assembly, the electrical connector comprising a glass assembly, an electrical contact surface on the glass assembly containing silver, and an electrical connector soldered to the electrical contact surface on the glass assembly by an alloy layer suitable as solder, the alloy having a mixture comprising: about 40 wt% tin, about 0.5 wt% copper, about 50 wt% indium; about 4.5 wt% silver, about 1.8 wt% to about 2.1 wt% nickel, and about 2.9 wt% to 3.2 wt% iron. The alloy may contain about 1.8 wt% nickel and about 3.2 wt% iron. Alternatively, the alloy may contain about 2.1 wt% nickel and about 2.9 wt% iron.

[0012] The sixth embodiment is an electrical connection on a glass assembly, the electrical connection comprising the glass assembly, an electrical contact surface containing silver on the glass assembly, and an electrical connector soldered to the electrical contact surface on the glass assembly by an alloy layer suitable as solder, the alloy having a mixture comprising about 14% to about 15% wt% tin, about 1% wt% antimony, about 1% wt% copper, about 5% to about 6% wt% silver, about 1% to about 3% wt% nickel, about 1% wt% zinc, and about 75% wt% indium. The alloy may contain about 14% wt% tin, 5% wt% silver, and about 3% wt% nickel. Alternatively, the alloy may contain about 15% wt% tin, 6% wt% silver, and about 1% wt% nickel.

[0013] The seventh embodiment is an electrical connection on a glass assembly, the electrical connector comprising a glass assembly, an electrical contact surface containing silver on the glass assembly, and an electrical connector soldered to the electrical contact surface on the glass assembly by an alloy layer suitable for use as solder, the alloy having a mixture comprising about 75% by weight tin, about 5% by weight silver, and about 20% by weight indium.

[0014] The eighth embodiment is an electrical connection on a glass assembly, the electrical connection comprising the glass assembly, an electrical contact surface containing silver on the glass assembly, and an electrical connector soldered to the electrical contact surface on the glass assembly by an alloy layer suitable for use as solder, the alloy having a mixture comprising about 7% by weight tin, about 3% by weight silver, and about 90% by weight indium.

[0015] According to another embodiment of the invention, a method for forming an indium-tin-silver based solder is provided. A ninth embodiment is a method for forming an alloy suitable for use as a solder, said method being formed by mixing tin, copper, indium, silver, nickel, and iron together. The method includes the steps of: adding tin to provide about 40% of the alloy weight; adding copper to provide about 0.5% of the alloy weight; adding indium to provide about 50% of the alloy weight; adding silver to provide about 4.5% of the alloy weight; adding nickel to provide about 1.8% to about 2.1% of the alloy weight; and adding iron to provide about 2.9% to about 3.2% of the alloy weight. The steps of adding nickel and adding iron are accomplished by adding a nickel-iron alloy to provide about 5% of the alloy weight, wherein the nickel-iron alloy comprises about 36% to about 42% by weight of nickel and about 58% to about 64% by weight of iron. The resulting alloy may contain about 1.8% by weight of nickel and about 3.2% by weight of iron. Alternatively, the resulting alloy contains approximately 2.1% by weight nickel and approximately 2.9% by weight iron.

[0016] A tenth embodiment is a method for forming an alloy suitable for use as a solder, the method comprising mixing tin, antimony, copper, indium, silver, nickel, and zinc together to form the alloy. The method includes the steps of: adding tin to provide about 14% to about 15% of the alloy weight; adding antimony to provide about 1% of the alloy weight; adding copper to provide about 1% of the alloy weight; adding silver to provide about 5% to about 6% of the alloy weight; adding nickel to provide about 1% to about 3% of the alloy weight; adding zinc to provide about 1% of the alloy weight; and adding indium to provide about 75% of the alloy weight. The resulting alloy may contain about 14% by weight of tin, 5% by weight of silver, and about 3% by weight of nickel. Alternatively, the alloy may contain about 15% by weight of tin, 6% by weight of silver, and about 1% by weight of nickel.

[0017] The eleventh embodiment is a method for forming an alloy suitable for use as a solder, the method comprising mixing tin, indium, and silver together to form the alloy. The method includes the steps of: adding tin to provide approximately 75% of the alloy by weight; adding silver to provide approximately 5% of the alloy by weight; and adding indium to provide approximately 20% of the alloy by weight.

[0018] The twelfth embodiment is a method for forming an alloy suitable for use as a solder, the method comprising mixing tin, indium, and silver together to form the alloy. The method includes the steps of: adding tin to provide approximately 7% of the alloy by weight; adding silver to provide approximately 3% of the alloy by weight; and adding indium to provide approximately 90% of the alloy by weight. Attached Figure Description

[0019] The invention will now be described by way of example with reference to the accompanying drawings, in which:

[0020] Figure 1 This is an interior view of a car rear window, which includes an electric defroster according to one embodiment.

[0021] Figure 2 According to one embodiment, the cross-section is shown as welded to Figure 1 A side view of an electrical connector with electrical contacts on a rear window, the connector having a rear window, electrical contacts, and solder.

[0022] Figure 3A and 3B This is a schematic diagram of a power connector, which is soldered using the solder composition of the present invention according to one embodiment;

[0023] Figure 4 This is a schematic diagram of a power connector being soldered to a windshield using the solder composition of the present invention according to one embodiment;

[0024] Figure 5 This is a temperature versus time curve during a temperature cycling test of an embodiment of the solder composition of the present invention according to one embodiment.

[0025] Figure 6 This is a schematic diagram of a tensile test using a force gauge to test the properties of the solder composition of the present invention according to one embodiment; and

[0026] Figure 7 This is a schematic diagram of a tensile test using weights to test the properties of the solder composition of the present invention according to one embodiment. Detailed Implementation

[0027] This invention provides a solder composition suitable for soldering electrical components to glass for electrically connecting electrical devices within or on the glass. See also Figure 1 The glass assembly (10), such as the rear window 10 of a car (e.g., also known as a backlight in Europe), is used as a non-limiting illustrative example. The rear window 10 includes a window defroster 12, which is composed of resistive defrosting lines 14 embedded in or deposited on the inner surface of the rear window 10. The defrosting lines 14 are electrically connected to a pair of electrical contact strips (electrical contact surfaces, also known as bus bars) 16 located on the inner surface of the rear window 10. The electrical contact strips 16 are composed of a conductive coating deposited on the inner surface of the rear window 10. Typically, the electrical contact strips 16 are formed of a silver-containing material.

[0028] The rear window 10 may additionally include, or alternatively include, an antenna 24 for receiving radio signals (e.g., an antenna connected to a radio receiver (not shown)). The antenna 24 has a conductive antenna element 26 embedded in or deposited on the inner surface of the rear window 10. The antenna element 26 is electrically connected to an electrical contact strip 16 located on the inner surface of the rear window 10. The electrical contact strip 16 is formed of a conductive coating deposited on the inner surface of the rear window 10. Typically, the electrical contact strip 16 is formed of a silver-containing material.

[0029] When soldering components to automotive glass, several challenges arise that are not present in other applications. To address concerns from original equipment manufacturers (OEMs) regarding the use of lead-free solder on automotive glass, automotive glass suppliers such as CLEPA (European Association of Automotive Suppliers) have developed several tests, including temperature cycling, climactic humidity, climactic temperature with humidity, and high-temperature storage. To address OEMs' concerns about solder melting points, one test involved storing glass samples soldered to connectors at 105°C for 500 hours while suspending 500g weights from each connector; the connectors did not detach from the glass during the test. However, OEMs (such as the European Automobile Manufacturers' Association, ACEA) have proposed temperatures as high as 115°C to 120°C.

[0030] The solder compositions of this invention have been developed to address the concerns of OEMs as described above. See also Figure 2Using standard soldering processes (e.g., resistance soldering apparatus, or flame, microflame, hot iron, hot air, and induction heating), the power connector 18 or antenna connector 30 is soldered to the respective electrical contact strips 16 on the rear window 10 using layer 20 of the solder composition of the present invention. Soldering can be performed in the ambient atmosphere without requiring an inert gas environment. The power line 22 can then be electrically connected to the power connector 18 to provide power to the window defroster 12, or the antenna line 28 can be electrically connected to the antenna connector 30 to provide a connection between the antenna 24 and the radio receiver (see [link]). Figure 1 Solder performance tests and results are provided below.

[0031] A first embodiment of an indium-tin-silver based alloy (hereinafter referred to as Alloy I) suitable for use as a solder is a mixture comprising: about 40 wt% tin, about 0.5 wt% copper, about 50 wt% indium; about 4.5 wt% silver, about 1.8 wt% to about 2.1 wt% nickel, and about 2.9 wt% to 3.2 wt% iron. Alloy I comprises about 1.8 wt% nickel and about 3.2 wt% iron. Alternatively, Alloy I may comprise about 2.1 wt% nickel and about 2.9 wt% iron.

[0032] The term “approximately X%” as used in this article can mean: for elements containing less than 25% by weight of the alloy, the percentage of the element can be changed by ±0.5% by weight; or for elements containing more than 25% by weight of the alloy, the percentage of the element can be changed by ±2% by weight.

[0033] Alloy I can also be characterized as a mixture comprising about 40 wt% tin, about 0.5 wt% copper, about 4.5 wt% silver, and about 5 wt% nickel-iron alloy, and about 50 wt% indium, wherein the nickel-iron alloy comprises about 36 wt% to about 42 wt% nickel and about 58 wt% to about 64 wt% iron. According to one embodiment, the nickel-iron alloy comprises about 36 wt% nickel and about 64 wt% iron. This specific nickel-iron alloy is commonly known by the trade name INVAR. According to one embodiment, the nickel-iron alloy comprises about 42 wt% nickel and about 58 wt% iron. This specific nickel-iron alloy is commonly known by the trade names ALLOY 42 or NILO 42. Alloy I has a solidus temperature of about 109.18°C and a liquidus temperature of about 115.39°C.

[0034] The solidus temperature is actually the temperature at which an alloy begins to melt. Below the solidus temperature, the substance is completely solid with no molten phase. The liquidus temperature is the highest temperature at which a crystalline (non-molten metal or alloy) can coexist with a melt. Above the liquidus temperature, the material is homogeneous, consisting only of the melt. Welding temperatures are a few degrees higher than the liquidus temperature; the exact difference is determined by the welding technique.

[0035] A second embodiment of an indium-tin-silver based alloy (hereinafter referred to as Alloy II) suitable for use as a solder is a mixture comprising about 14 to about 15 wt% tin, about 1 wt% antimony, about 1 wt% copper, about 5 to about 6 wt% silver, about 1 wt% to about 3 wt% nickel, about 1 wt% zinc, and about 75 wt% indium. Alloy II may comprise about 14 wt% tin, 5 wt% silver, and about 3 wt% nickel, hereinafter referred to as Alloy IIA. Alternatively, Alloy II may comprise about 15 wt% tin, 6 wt% silver, and about 1 wt% nickel, hereinafter referred to as Alloy IIB. Alloy IIA has a solidus temperature of about 122.41°C and a liquidus temperature of about 135.66°C. Alloy IIN has a solidus temperature of about 123.68°C and a liquidus temperature of about 138.38°C.

[0036] A third embodiment of an indium-tin-silver based alloy (hereinafter referred to as Alloy III) suitable for use as a solder is a mixture comprising about 75% by weight tin, about 5% by weight silver, and about 20% by weight indium. Alloy III has a solidus temperature of about 177.26°C and a liquidus temperature of about 188.29°C.

[0037] A fourth embodiment of an indium-tin-silver based alloy (hereinafter referred to as Alloy IV) suitable for use as a solder is a mixture comprising about 7% by weight tin, about 3% by weight silver, and about 90% by weight indium. Alloy IV has a solidus temperature of about 134.58°C and a liquidus temperature of about 139.58°C.

[0038] Another embodiment of the invention relates to electrical connections on glass assemblies, such as... Figure 1 and 2 As shown, the electrical connection includes: a glass assembly, a silver-containing electrical contact surface on the glass assembly, and an electrical connector, the electrical connector being soldered to the electrical contact surface on the glass assembly with a layer of solder. In four different embodiments of this electrical connection, the solder can be any of alloys I, II, III, or IV.

[0039] Other embodiments of the invention relate to a method for forming an alloy suitable for use as a solder. According to a first embodiment of the method for forming alloy I, the method includes the steps of: adding tin to provide about 40% of the alloy weight; adding copper to provide about 0.5% of the alloy weight; adding indium to provide about 50% of the alloy weight; adding silver to provide about 4.5% of the alloy weight; adding nickel to provide about 1.8% to about 2.1% of the alloy weight; and adding iron to provide about 2.9% to about 3.2% of the alloy weight. In one specific embodiment, alloy I comprises about 1.8% by weight of nickel and about 3.2% by weight of iron. In another specific embodiment, alloy I comprises about 2.1% by weight of nickel and about 2.9% by weight of iron.

[0040] The steps of adding nickel and adding iron are accomplished by adding a nickel-iron alloy to provide approximately 5% of the alloy by weight, wherein the nickel-iron alloy comprises approximately 36% to approximately 42% by weight of nickel and approximately 58% to approximately 64% by weight of iron. In one specific embodiment, the nickel-iron alloy comprises 36% nickel and 64% iron (INVAR), and in another specific embodiment, the nickel-iron alloy comprises 42% nickel and 58% iron (ALLOY 42). This provides the advantage that the process of adding elements to alloy I is simplified by weighing and adding a single amount of commercially available nickel-iron alloy (rather than weighing and adding a first amount of nickel and a second amount of iron separately).

[0041] According to a second embodiment of the method for forming Alloy II, the method includes the steps of: adding tin to provide about 14% to about 15% of the alloy weight; adding antimony to provide about 1% of the alloy weight; adding copper to provide about 1% of the alloy weight; adding silver to provide about 5% to about 6% of the alloy weight; adding nickel to provide about 1% to about 3% of the alloy weight; adding zinc to provide about 1% of the alloy weight; and adding indium to provide about 75% of the alloy weight. According to one embodiment, Alloy II comprises about 14% by weight tin, 5% by weight silver, and about 3% by weight nickel. According to another embodiment, Alloy II comprises about 15% by weight tin, 6% by weight silver, and about 1% by weight nickel.

[0042] According to a third embodiment of the method for forming alloy III, the method includes the steps of: adding tin to provide about 75% of the alloy weight; adding silver to provide about 5% of the alloy weight; and adding indium to provide about 20% of the alloy weight.

[0043] According to a fourth embodiment of the method for forming alloy IV, the method includes the steps of: adding tin to provide about 7% alloy weight; adding silver to provide about 3% alloy weight; and adding indium to provide about 90% alloy weight.

[0044] Content performance test and results

[0045] I. Temperature Cycling Test

[0046] The test sample was a windshield with power and antenna connectors 18 and 30 welded with alloys II and IV. Figure 3A and 3B Schematic diagrams of bridging end power connectors 18a and 18b are shown, each having a raised, elongated bridge extending between two spaced solder pads 19 located at both ends. Hereinafter, power connectors 18a and 18b are referred to as power connector 18. The area of ​​each solder pad 19 is approximately 64 mm². 2 And as Figure 4 As shown, the thickness of the solder composition is approximately 0.5 mm. The power connector 18 is soldered to the rear window 10 as follows: a solder ingot is rolled into a solder strip, the solder strip is reflowed onto a base copper material in continuous strips, the solder strip is shaved to a uniform size, the ends are stamped and formed using a standard tool, flux is applied to the solder surface, and the power connector 18 is soldered to the target area of ​​the electrical contact strip 16 of the rear window 10 using a resistance soldering apparatus with an energy input range of approximately 750 watt-seconds to approximately 1050 watt-seconds, for example, approximately 900 watt-seconds, followed by cooling while holding the power connector 18 in place in the rear window 10 for approximately 8 seconds to approximately 12 seconds, for example, approximately 10 seconds.

[0047] In this experiment, such as Figure 5 As shown, the temperature of the climate control chamber cycles as follows: over a total period of 8 hours, it is raised from room temperature (approximately 20°C) to -40°C, held at -40°C for 90 minutes, then raised to 105°C over a period of 120 minutes, before returning to room temperature. Figure 5 As indicated by the arrows, a 14V current load is applied through power line 22 starting from the end of the -40°C step and ending at the end of the 105°C step. After 20 cycles, as... Figure 6 As shown, in the tensile test 300 (at room temperature), each power connector 18 was pulled in a direction substantially perpendicular to the solder layer 20 and the rear window 10 to a force of 50 Newtons on an electronic force gauge for 3 seconds. The electronic force gauge was connected to the power connector 18 at approximately the midpoint between the solder pads 19 via a hook 320 and was manually operated via a handle 330. No failures occurred in this test.

[0048] II. Thermal Insulation Test

[0049] The test sample was a windshield with power and antenna connectors 18 and 30 welded with Alloy II and Alloy IV. In this test 400, as... Figure 7 As shown, the temperature of the climate control box was maintained at 105°C for 96 hours, with a 14V current load applied for 15 minutes per hour through power line 22. During the entire 96 hours, a 10-Newton mechanical load was applied directly vertically downwards with gravity to power connector 18, substantially perpendicular to the solder layer 20 and rear window 10 (applied by attaching a weight 410 to power connector 18 via a hook 420 located approximately at the midpoint between solder pads 19). A similar 3-Newton mechanical load was applied to antenna connector 30. After the 96-hour test, each power connector 18 was... Figure 6 As shown and described above, a pulling force (at room temperature) was applied to an electronic force gauge (Mark-10, Long Island, New York, model BG50) at a rate of 280 to 360 Newtons for 3 seconds. During this test, the power connector 18 did not fail. The antenna connector 18 was similarly tested with forces ranging from 30 to 70 Newtons. Ten of the 18 antenna connectors 18 soldered with Alloy IV failed.

[0050] III. High-Temperature Storage Test

[0051] The test sample was a windshield with power and antenna connectors 30 and 18 welded with Alloy II and Alloy IV. In this test, the temperature of the climate control box (in a relatively dry but uncontrolled environment) was maintained at a constant 105°C for 24 hours without any electrical or mechanical load on the power connectors 18. After 24 hours, each power connector 18 was... Figure 6 As shown and described above, a pulling force (at room temperature) was applied to the electronic force gauge, ranging from 210 to 290 Newtons, for 3 seconds. Antenna connector 30 was similarly tested by pulling each antenna connector 18 with a force ranging from 50 to 75 Newtons. During this test, neither the power supply nor the antenna connectors 18 and 30 failed.

[0052] IV. Tests with long-term electrical load

[0053] The test sample was a windshield with power and antenna connectors 18 and 30 welded with Alloy II. In this test, the temperature of the climate control box (relatively dry but uncontrolled humidity) was maintained at a constant 105°C for 500 hours under a 14V electrical load. After 500 hours, each power connector 18 was... Figure 6 As shown and described above, a pulling action was performed (at room temperature) until a force of 50 Newtons was applied to the electronic force gauge for 3 seconds. No failures occurred in this experiment.

[0054] V. Thermal Shock Test

[0055] The test sample was a windshield with power and antenna connectors 18 and 30 welded with Alloy IV. In this test, one cycle consisted of heating the sample to 105°C for 1 hour in a climate-controlled chamber without electrical or mechanical load, followed by complete immersion in cold water (approximately 23°C or lower, from a refrigerator). After each cycle, the sample was dried with compressed air. After 5 cycles and subsequently 10 cycles, each power connector 18 was... Figure 6 As shown and described above, the antenna connector 18 was subjected to a pulling force (at room temperature) of 17 to 290 Newtons on an electronic force gauge for 3 seconds. Similarly, the antenna connector 18 was tested with a pulling force of 50 to 80 Newtons. No failures were observed in this test.

[0056] VI. High Humidity Test: Constant Climate

[0057] The test sample was a windshield with power and antenna connectors 18 and 30 welded with Alloy II. The samples were exposed in an ambient chamber at a constant temperature of 80°C and >96% RH for a total of 504 hours. From the moment the specified temperature and humidity were reached, a current of 14V (approximately 22A) was applied to the power connector 18 for 15 minutes, and thereafter, a load was applied for 15 minutes every 24 hours until the end of the 504 hours. After the 504 hours, each power connector 18 was... Figure 6 As shown and described above, a pulling action was performed (at room temperature) until a force of 50 Newtons was applied to the electronic force gauge for 3 seconds. No failures occurred in this experiment.

[0058] VII. Performance of Windshield Washer Fluid

[0059] The test sample was a windshield with power and antenna connectors 18 and 30 welded with Alloy II and Alloy IV. In this test, the power and antenna connectors 18 and 30 were immersed in a simulated windshield washer fluid (69.5% distilled water, 20% ethanol, 10% isopropanol, 0.5% ethylene glycol, and 0.09% sodium lauryl sulfate) at 23°C for 24 hours. After 24 hours, each power connector 18 was... Figure 6 As shown and described above, a pulling force (at room temperature) was applied to the force gauge to a force of 70 to 310 Newtons for 2 seconds. Each antenna connector 30 was similarly tested with a force of 60 to 85 Newtons. No failures were observed in this test.

[0060] VII. Salt spray test

[0061] The test sample was a windshield with power and antenna connectors 18 and 30 welded with Alloy II. In this test, the test sample was exposed to salt spray in a test chamber for 96 hours. The salt concentration was 5%, and the pH was 6.5 to 7.2. The salt spray temperature was set at +35°C ± 2°C, and the tower temperature was set at +48°C, with an air pressure of 16 to 18 psi. After 96 hours, each power connector 18 was... Figure 6 As shown and described above, a force of 50 Newtons was applied for 2 seconds at room temperature. No failures occurred in this experiment.

[0062] The solder composition of this invention is a lead-free alloy that transmits high operating temperatures and, depending on the subject application, imparts mechanical properties combining strength and ductility, as well as physical properties of wetting and stability, while providing the required manufacturability. The required manufacturability includes sufficiently low processing temperatures to mitigate or eliminate manufacturing defects or failures, and to mitigate or eliminate silver scavenging (purification) that frequently occurs in soldering silver-containing metallized electrical contact surfaces. This is achieved through indium-tin-silver based materials, or indium-tin-silver based materials that can be metallurgically alloyed, precipitated, or dispersed with copper, nickel, and iron or antimony.

[0063] As used in this application, in some embodiments, solder compositions consisting essentially of the listed materials are limited to the specified materials and those materials that do not substantially affect the fundamental and novel properties of the solder composition and the electrical connector containing the solder composition. The fundamental and novel properties of the solder composition include thermal properties (e.g., liquidus temperature and solidus temperature) and mechanical properties (e.g., performance tests as described herein).

[0064] In addition to providing environmentally friendly lead-free materials, the present invention also has many advantages, such as providing lead-free solder that can be used on automotive glass, provides the necessary mechanical properties of both strength and ductility, and can withstand the required elevated operating temperatures while maintaining the required low manufacturing processing temperatures.

[0065] Although the invention has been described with reference to preferred embodiments, it is not intended to be limited in this way, but rather to be limited only by the scope set forth in the appended claims. Furthermore, the use of the terms first, second, etc., does not indicate any significant order, but is used to distinguish one element from another. Additionally, the use of the terms an, a, etc., does not indicate a limitation on quantity, but rather indicates the presence of at least one of the stated items.

Claims

1. An alloy suitable for use as a solder, said alloy comprising: Tin, approximately 14% by weight to approximately 15% by weight; Approximately 1% by weight of antimony; Approximately 1% by weight of copper; Approximately 5% to 6% by weight of silver; Approximately 1% to 3% by weight of nickel; Approximately 1% by weight of zinc; and Approximately 75% by weight of indium, of which, "Approximately X%" means: for elements containing less than 25% by weight of the alloy, the percentage of the element changes by ±0.5% by weight, or for elements containing more than 25% by weight of the alloy, the percentage of the element changes by ±2% by weight.

2. The alloy as described in claim 1, characterized in that, The alloy contains about 14% by weight tin, about 5% by weight silver, and about 3% by weight nickel.

3. The alloy as described in claim 1, characterized in that, The alloy contains about 15% by weight tin, about 6% by weight silver, and about 1% by weight nickel.

4. The alloy as described in claim 1, characterized in that, The solidus temperature of the alloy is in the range of 122°C to 124°C, and the liquidus temperature is in the range of 136°C to 138°C.

5. An electrical connection on a glass assembly, comprising: Glass components; The silver-containing electrical contact surface on the glass assembly; Electrical connectors; as well as The alloy layer as described in claim 1, suitable for use as solder, is located between the electrical connector and the electrical contact surface, thereby attaching the electrical connector to the electrical contact surface.

6. The electrical connector as claimed in claim 5, characterized in that, The alloy contains about 14% by weight tin, about 5% by weight silver, and about 3% by weight nickel.

7. The electrical connector as claimed in claim 5, characterized in that, The alloy contains about 15% by weight tin, about 6% by weight silver, and about 1% by weight nickel.

Images