US20070036670A1

Movatterモバイル変換

Info

Publication number: US20070036670A1
Application number: US11/359,864
Authority: US
Inventors: John Pereira
Original assignee: Antaya Technologies Corp
Current assignee: Antaya Technologies Corp
Priority date: 2005-08-12
Filing date: 2006-02-22
Publication date: 2007-02-15

Abstract

A solder composition having a mixture of elements including tin, indium, silver, and bismuth, and can include about 30% to 85% tin and about 15% to 65% indium.

Description

RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No. 11/202,640, filed Aug. 12, 2005. The entire teachings of the above application are incorporated herein by reference.

BACKGROUND

Electrical connectors are typically used for making electrical connections to devices such as antennas and defrosters, which are incorporated on or embedded within automotive glass. The electrical connectors are commonly soldered to the glass with a solder that contains lead. Due to environmental concerns, most industries are currently using or planning to use low or non-lead solders for various soldering applications. A common non-lead solder employed in some industries, contains a high tin (Sn) content, for example 95% tin. However, there are difficulties encountered when soldering devices to automotive glass that are not present in other fields. Automotive glass tends to be brittle, and the common high tin, non-lead solders that are suitable for use in other applications can typically cause cracking of the automotive glass. Although materials such as ceramics and silicon might appear to be similar in some respects to automotive glass, some solders that are suitable for soldering to ceramic or silicon devices are not suitable for soldering to automotive glass.

SUMMARY

The present invention provides a solder article that can be suitable for soldering to automotive glass and can be lead free.

The solder article can be a multilayer solder article that includes a layer of a first non-lead solder for bonding to an electrically conductive material. A layer of a second non-lead solder can be on the layer of the first solder. The second solder can have a lower melting temperature than the first solder. The melting temperature of the second solder can be below about 310° F.

In particular embodiments, the second solder can be suitable for soldering to automotive glass and can be a softer material than the first solder. The first solder can have a melting temperature of about 465° F. and the second solder can have a melting temperature of about 250° F. The first solder can be a tin and silver composition having about 70% or greater tin, and the second solder can have an indium, tin, silver and copper composition of at least about 40% indium and less than about 55% tin. In some embodiments, the second solder can have a composition of about 50% or more indium, a maximum of about 30% tin, about 3% to 5% silver and about 0.25% to 0.75% copper. In one embodiment, the first solder can be about 95% tin and about 5% silver, and the second solder can be about 65% indium, about 30% tin, about 4.5% silver and about 0.5% copper. The layers of the first and second solders can have a combined thickness ranging between about 0.007 to 0.040 inches, and in some embodiments, can be about 0.013 to 0.015 inches. The layer of the first solder can range between about 0.005 to 0.010 inches thick. The layer of the second solder can range between about 0.001 to 0.008 inches thick, and in some embodiments, can range between about 0.005 to 0.008 inches thick. The layers of the first and second solders can be bonded on a base substrate formed of electrically conductive material. The base substrate can be made of sheet metal such as a band of copper. The multilayer solder article can be an electrical device such as an electrical connector.

An electrical device in the present invention can include a base formed of electrically conductive material. A layer of a first non-lead solder can be on the base. A layer of a second non-lead solder can be on the layer of the first solder. The second solder can have a lower melting temperature than the first solder. The melting temperature of the second solder can be below about 310° F.

The present invention additionally provides a method of making a multilayer solder article including providing a layer of a first non-lead solder. A layer of a second non-lead solder can be bonded against the layer of the first solder by cold rolling the layers of the first and second solders together between a pair of rollers. The layer of the second solder can have a lower melting temperature than the layer of the first solder. The melting temperature of the second solder layer can be below about 310° F.

In particular embodiments, the layer of the first solder can be formed on a surface of a base substrate formed from a sheet of electrically conductive material. A sheet of the first solder can be applied on the surface of the base substrate and melted on the base substrate with a heat source. The first solder can be a band which is applied on a base substrate band. Flux can be applied between the first solder and the base substrate. The first solder can be trimmed to a desired dimension on the base substrate. A band of the second solder can be cold rolled on the first solder. Cold rolling of the second solder against the first solder can be performed without requiring pre-treatment of mating surfaces of the first and second solders. The combined thickness of the layers of the first and second solders can be reduced by about 30% to 50% during the cold rolling. The layers of solder can be heated with a heat source after cold rolling. The first and second solders can be aligned with each other before cold rolling within a guide device, which can be stationary.

The second solder can be selected to be softer than the first solder. The first solder can have a melting temperature of about 465° F. and the second solder can have a melting temperature of about 250° F. The first solder can have a tin and solder composition having about 70% or greater tin, and the second solder can have an indium, tin, silver and copper composition of at least about 40% indium and less than about 55% tin. In some embodiments, the second solder can have a composition of 50% or more indium, a maximum of about 30% tin, about 3% to 5% silver and about 0.25% to 0.75% copper. In one embodiment, the first solder can be about 95% tin and about 5% silver, and the second solder can be about 65% indium, about 30% tin, about 4.5% silver and about 0.5% copper.

The base substrate can be formed from sheet metal such as a band of copper. The multilayer solder article can be further formed into an electrical device such as an electrical connector. The layers of the first and second solders can have a combined thickness ranging between about 0.007 to 0.040 inches, and in some embodiments, can be about 0.013 to 0.015 inches. The layer of the first solder can range between about 0.005 to 0.010 inches thick. The layer of the second solder can range between about 0.001 to 0.008 inches thick, and in some embodiments can range between about 0.005 to 0.008 inches thick.

The present invention further provides a method of soldering an electrical device to automotive glass including providing a layer of a first non-lead solder on the electrical device. A layer of a second non-lead solder is provided on the layer of the first solder. The second solder can have a lower melting temperature than the first solder. The melting temperature of the second solder can be below about 310° F. The electrical device can be oriented relative to the automotive glass to position the layer of the second solder against the glass. A preselected amount of heat can be applied to the second solder for melting the layer of the second solder without substantively melting the layer of the first solder for soldering the electrical device to the automotive glass.

The layer of the first solder can be provided on a metal base of the electrical device which can be formed of copper. The first and second solders can have similar configurations, dimensions, compositions and properties as those previously discussed above.

The present invention also provides an electrical device including a base formed of electrically conductive material, and a layer of a first non-lead solder on the base. A layer of a second non-lead solder is on the layer of the first solder. The second solder can have a composition including tin, indium, silver and copper. The second solder has a lower melting temperature than the first solder.

In particular embodiments, the second solder can have a melting temperature below about 360° F. In some embodiments, the second solder can have a melting temperature below about 315° F., and in other embodiments, the second solder can have a melting temperature below about 310°0 F. The second solder can have a composition including at least about 50% tin, at least about 10% indium, about 1% to 10% silver, and about 0.25% to 0.75% copper. In one embodiment, the second solder can include about 60% tin, about 35% indium, about 4.5% silver, and about 0.5% copper. The second solder can have a melting temperature of about 300° F. The first solder can include tin and silver with about 70% or greater tin. The first solder can include about 95% tin and about 5% silver. The first solder can have a melting temperature of about 465° F. The base can be made of sheet metal such as copper. The electrical device can be an electrical connector.

The present invention additionally provides a multilayer solder article including a layer of a first non-lead solder for bonding to an electrically conductive material, and a layer of a second non-lead solder on the layer of the first solder. The second solder can have a composition including tin, indium, silver and copper. The second solder can have a lower melting temperature than the first solder and can be suitable for soldering to automotive glass.

In particular embodiments, the first and second solders can be as described herein. In addition, the article can further include a base substrate formed of an electrically conductive material on which the layers of the first and second solders are bonded. The base substrate can be made of sheet metal such as a band of copper.

The present invention can also provide a method of making a multilayer solder article including providing a layer of a first non-lead solder, and bonding a layer of a second non-lead solder against the layer of the first solder by cold rolling the layers of the first and second solders together between a pair of rollers. The second solder can have a composition including tin, indium, silver and copper. The layer of the second solder has a lower melting temperature than the layer of the first solder.

The present invention can further provide a method of soldering an electrical device to automotive glass including providing a layer of a first non-lead solder on the electrical device. A layer of a second non-lead solder is provided on the layer of the first solder. The second solder can have a composition including tin, indium, silver and copper. The second solder has a lower melting temperature than the first solder. The electrical device can be oriented relative to the automotive glass to position the layer of the second solder against the glass. A preselected amount of heat can be applied to the second solder for melting the layer of the second solder without substantially melting the layer of the first solder for soldering the electrical device to the automotive glass.

In particular embodiments, the first and second solders can be as described herein.

The present invention can also provide a solder composition having a mixture of elements including tin, indium, silver, and bismuth, and can include about 30% to 85% tin and about 15% to 65% indium.

In particular embodiments, the solder composition can further include copper. The composition can include about 1% to 10% silver, about 0.25% to 6% bismuth, and about 0.25% to 0.75% copper. In some embodiments, the composition can include about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. The composition can include about 50% to 83% tin, and about 15% to 45% indium. The composition can have a solidus temperature below about 315° F.

The present invention can also provide a solder composition having a mixture of elements including tin, indium, silver, and bismuth, and can include about 30% to 85% tin, about 13% to 65% indium, and about 0.25% to 4% bismuth.

In particular embodiments, the composition can include copper. The composition can include about 1% to 10% silver, and about 0.25% to 0.75% copper. In some embodiments, the composition can include about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. The composition can include about 50% to 83% tin, and about 13% to 45% indium. In some embodiments, the composition can include about 15% to 45% indium. The composition can have a solidus temperature below about 315° F.

The present invention can also provide a solder composition having a mixture of elements including tin, indium, silver, bismuth and copper, and can include about 30% to 85% tin and about 13% to 65% indium.

The present invention can also provide a solder composition including tin, indium and silver, and having more than about 60% tin and a solidus temperature below about 330° F.

In particular embodiments, the solidus temperature can be below about 315° F. The composition can further include bismuth, and some embodiments can further include copper.

The present invention can also provide a method of forming a solder composition including mixing tin, indium, silver, and bismuth together, and including about 30% to 85% tin, and about 15% to 65% indium.

The present invention can also provide a method of forming a composition including mixing tin, indium, silver, and bismuth together, and including about 30% to 85% tin, about 13% to 65% indium, and about 0.25% to 4% bismuth.

The present invention can also provide a method of forming a solder composition including mixing tin, indium, silver, bismuth and copper together, and including about 30% to 85% tin, and about 13% to 65% indium.

The present invention can also provide a method of forming a solder composition including mixing tin, indium and silver together, including more than about 60% tin, and providing the composition with a solidus temperature below about 330° F.

The present invention can also provide a method of soldering including providing a solder composition having a mixture of elements including tin, indium, silver and bismuth, and including about 30% to 85% tin, and about 15% to 65% indium. The solder composition is then melted with a soldering device.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1 is a schematic drawing of an embodiment of an apparatus for forming a multilayer solder article.

FIG. 2 is a front schematic view of an embodiment of a rolling device or mill depicted inFIG. 1.

FIG. 3 is a front view of an embodiment of a guide for guiding material into the rolling mill.

FIG. 4 is a cross section of a clad band having a base substrate clad with a layer of a first or higher melting temperature solder.

FIG. 5 is a schematic drawing of an embodiment of a process and apparatus for forming the clad band ofFIG. 4.

FIG. 6 is a cross section of an embodiment of a multilayer solder article including a base substrate having a multilayer solder with a layer of a first or higher melting temperature solder and a layer of a second or lower melting temperature solder covering the first solder.

FIG. 7 is a schematic drawing of an electrical connector having a multilayer solder prior to soldering to automotive glass.

FIG. 8 is a schematic drawing of the device ofFIG. 7 after soldering to automotive glass.

FIG. 9 is an inside view of a rear window of an automobile including an electrically operated defroster.

FIG. 10 is a side view of an electrical connector soldered to an electrical contact on the rear window ofFIG. 9, with the rear window, electrical contact and solder being shown in section.

DETAILED DESCRIPTION

FIG. 1 depicts an embodiment of anapparatus10 for forming a multilayer solder article24 (FIG. 6). Themultilayer solder article24 can have amultilayer solder15 which can include afirst solder13 and asecond solder16. When forming themultilayer solder article24, a clad ribbon, strip, belt or band12 (FIG. 4), having an electricallyconductive base substrate11 and a layer of afirst solder13 on one surface, can be pulled from a roll12aat an unwind station. Thefirst solder13 can be a higher melting point or temperature solder. Thebase substrate11 can be a ribbon, strip, belt or band of sheet metal suitable for forming electrical devices, such as electrical connectors, by stamping.

Theclad band12 can be moved through aguide20 to align theclad band12 with a rolling device or mill14 (FIG. 2). A ribbon, strip, belt orband16bof a second or lower melting point ortemperature solder16 can be pulled from aroll16aat an unwind station for positioning on or over the highermelting temperature solder13. Thesecond solder16 can be softer or more ductile than thefirst solder13. Theband16bof thesecond solder16 can be moved through the guide20 (FIG. 3) for alignment with both theclad band12 and the rollingmill14. Theguide20 can align theband16bof thesecond solder16 relative to or with thefirst solder13 and thebase substrate11.

Theband16bof thesecond solder16 and theclad band12 can be cold rolled together by rollingmill14 between first or upper18a,and second or lower18brollers of aroll system18. Cold rolling can combine or bond thesecond solder16 with thefirst solder13 to form themultilayer solder article24. Aheating station26 can be positioned after the rollingmill14 for heating themultilayer solder article24 to ensure a sufficient bond between thefirst solder13 and thesecond solder16, but without melting the

solders

13 or16. Theheating station26 can be a flame heater positioned under thebase substrate11 as shown, or in other embodiments, can be an oven, hot air gun, etc. The multilayer solder article24 (FIG. 6) can then be wound up in aroll24aat a windup station.

In particular embodiments, theguide20 can be secured to the rollingmill14 close to therollers18a/18b.The position of theguide20 can be adjusted by an adjustment device22 (FIG. 1). Theguide20 can include a first orupper portion32 and a second orlower portion34 which are shaped and fastened together to form alongitudinal passage36 through the guide20 (FIG. 3). Thelower portion34 can have agroove34awhich is sized to guide thebase substrate11 through theguide20 and theupper portion32 can have agroove32awhich is sized and positioned for guiding theband16bof thesecond solder16 in alignment with thefirst solder13 on thebase substrate11. Theguide20 can commence the combining of thesecond solder16 with thefirst solder13 and thebase substrate11. The downstream end of theguide20 can be contoured such as in a tapered or curved manner in order to be positioned closely between and adjacent to

rolls

18aand18b.

In one embodiment, thegroove34acan be about 0.01 inches wider and 0.004 inches higher than the width and thickness of thebase substrate11. In addition, thegroove32acan be about 0.025 inches wider than the width of thesolder13 on thebase substrate11 and about 0.010 inches higher than the combined height or thicknesses of thefirst solder13 and theband16bof thesecond solder16.

Referring toFIGS. 1 and 2, the rollingmill14 can include aframe30 to which the

rolls

18aand18bare rotatably mounted about first or upper17a,and second or lower17baxes, respectively. Agear system28 can be connected to theroller system18 for causing the

rolls

18aand18bto rotate in unison. Thegear system28 can include a first orupper gear28athat is secured to roll18aalongaxis17a,and a second orlower gear28bthat is secured to roll18balongaxis17b.

Gears

28aand28bcan be engaged or intermeshed with each other. The rollingmill14 can be driven by amotor drive29, or can be rotated by the movement of the cladband12 and thesecond solder16 passing between the

rolls

18aand18b.Thespace35 between the

rolls

18aand18bcan be adjusted by anadjustment fixture33 to provide the desired amount of pressure on theclad band12 andsolder16 during the rolling process in order to bond thesecond solder16 to thefirst solder13 by cold rolling. In some embodiments, thespace35 between

rolls

18aand18bcan be set to reduce the initial combined height or thickness of thefirst solder13 and thesecond solder16 by about 30% to 50%. Theadjustment fixture33 can include a pair ofcylinders31, for example, hydraulic or pneumatic cylinders, for positioningroll18aandaxis17arelative to roll18bandaxis17b,and providing rolling pressure. Thecylinders31 can be secured to anadjustable plate37, which can be adjusted, for example, with adjustment screws (not shown) to change the position of thecylinders31.

The cold rolling by rollingmill14 can be performed without requiring pretreatment of the mating surfaces of the first13 and second16 solders (for example, the removal of contaminants such as oxides, by chemical, energy or mechanical means). The thickness reduction and material deformation of the first13 and second16 solders during the cold rolling process can provide sufficient pressure, heat or material changes for bonding to occur between the layers of the first13 and second16 solders. In some embodiments, theheating station26 can be omitted. In other embodiments, thebase substrate11 can be omitted so that the first13 and second16 solders are alone combined by the rollingmill14 to form a multilayer solder article. Theguide20 can be modified to accommodate the omission of thebase substrate11.

Theband9 of thefirst solder13 can initially be about 0.016 inches thick and the thickness of thefirst solder13 can be reduced to about 0.005 to 0.010 inches thick by trimming, machining or skiving. Thickness reduction can also include cold rolling. Theband16bof thesecond solder16 can initially be about 0.010 inches thick and the thickness of thesecond solder16 can be reduced to about 0.005 to 0.008 inches thick by trimming and/or cold rolling. The total thickness ofmultilayer solder15 can be about 0.013 to 0.015 inches thick. In some embodiments, themultilayer solder15 can be about 0.007 to 0.040 inches thick. In other embodiments,solder13 can be even thinner or omitted, and the layer of thesecond solder16 can range between about 0.001 to 0.008 inches thick. Depending upon the application at hand, the thicknesses can be even higher or lower than those described above. Thesecond solder16 can be softer and more ductile than thefirst solder13. In particular embodiments, themultilayer solder15 can be formed of generally lead free compositions that are suitable for cold rolling by the rollingmill14 ofapparatus10.

Referring toFIG. 4, theclad band12 can be pre-formed prior to being processed byapparatus10. This can be accomplished by embodiments of theapparatus8 depicted inFIG. 5 where a moving band of thebase substrate11 can haveflux46aapplied to a surface of thebase substrate11 at aflux station46, such as by a brush, roller dispenser, etc. A ribbon, strip, belt orband9 of the first or highermelting temperature solder13 can be applied by aroller48 over theflux46aand against thebase substrate11. Theband9 of thefirst solder13 can then be melted or reflowed at aheating station50, such as by flames, oven, hot air gun, etc., to melt and bond theband9 to thebase substrate11 as reflowedsolder9a.If desired, a skiving or trimmingstation52 can be included for trimming the reflowedsolder9aand/or thebase substrate11 to result in cladband12 with a trimmedlayer9bof the first or highermelting temperature solder13 at desired dimensions. The desired dimensions can be thickness and/or width. The trimming can also be performed on a separate processing machine. Theclad band12 can be wound up in a roll12afor processing onapparatus10. In some embodiments, theclad band12 can be fed directly into rollingmill14 for combining with theband16bof thesecond solder16. Althoughflux46ahas been described for treating the surfaces to allow thefirst solder13 to bond to thebase substrate11, other suitable treatments can be employed.

Referring toFIG. 6, themultilayer solder article24 produced by apparatus10 (FIG. 1) can have amultilayer solder15 where the first or highermelting temperature solder13 can be positioned or bonded against thebase substrate11 and the second or highermelting temperature solder16 can be bonded over thefirst solder13. Themultilayer solder15 can be a strip that is narrower than thebase substrate11 and can be located along a longitudinal axis of thebase substrate11, for example, the central longitudinal axis. As a result, only a portion of thebase substrate11 can be covered by themultilayer solder15 so that side margins of thebase substrate11 are exposed. Thebase substrate11 can be made of a material, such as sheet metal that is suitable for forming into electrical devices. In one embodiment,base substrate11 can be made of copper, for example, C110 that is about 0.031 inches thick and about 1.812 inches wide. Thebase substrate11 can be trimmed down to a width of about 1.56 inches. Themultilayer solder15 can be about 0.620 inches wide and centered onbase substrate11 with about 0.448 inch margins on each side. Depending upon the situation at hand, other materials such as steel can be employed, and thebase substrate11 and/ormultilayer solder15 can have other suitable dimensions.

In some embodiments, the width of thebase substrate11 can be trimmed before stamping begins. Thebase substrate11 can be trimmed by a trimmingstation52, onapparatus8,apparatus10, or on a separate processing machine. Themultilayer solder15 can also be trimmed to desired configurations and dimensions by trimmingstation52 onapparatus10, or on a separate processing machine. For example, the width and/or thickness of themultilayer solder15 can be trimmed. In addition, the layer of thefirst solder13 can be made narrower than the layer of thesecond solder16 to reduce the possibility of thefirst solder13 from contacting soldering surfaces. Alternatively, asecond solder16 that is wider than thefirst solder13 can also be cold rolled over thefirst solder13.

Referring toFIG. 7, themultilayer solder article24 can be formed into solder clad electrical devices of various configurations, including anelectrical connector40, such as by stamping processes, by feeding theroll24ainto the appropriate processing machinery. Theelectrical connector40 can include aconnector portion38 which is formed from thebase substrate11 into a desired configuration, for example, to engage a mating connector. Themultilayer solder15 can be located on theelectrical connector40 in a location suitable for solderingelectrical connector40 to a surface, such as on abase39. The layer of the first or highermelting temperature solder13 can be sandwiched between the base39 of theconnector portion38 and the layer of the second or lowermelting temperature solder16.

For embodiments of theelectrical connector40 that are suitable for soldering toautomotive glass42, thefirst solder13 can have a composition that is suitable for bonding to the material ofconnector portion38, for example, copper, and thesecond solder16 can have a composition that is suitable for bonding to aterminal pad44 on the surface ofautomotive glass42. The first or highermelting temperature solder13 can be a tin (Sn) and silver (Ag) solder, for example, having about 70% or greater tin, by weight. For example, in one embodiment,solder13 can be a tin and silver, solder having a composition of about 95% tin and about 5% silver, by weight (95Sn 5Ag). In other embodiments,solder13 can have a variety of different amounts of tin, such as about 97Sn 3Ag, 90Sn 10Ag, 80Sn 20Ag, etc. In addition, some of the silver can be replaced by other elements. Although thefirst solder13 is suitable for being bonded to theconnector portion38, thefirst solder13 might not be suitable for soldering to theautomotive glass42, and might cause cracking of theglass42. It has been observed by the Applicant that high tin solders typically cause cracking of automotive glass.

On the other hand, the second or lowermelting temperature solder16 can have a lower tin (Sn) content and high indium (In) content to allow soldering toautomotive glass42 without cracking theglass42. Thesecond solder16 can be positioned on thebase39 ofconnector portion38 to contact theautomotive glass42 and also to prevent contact of thefirst solder13 with theglass42. Thesecond solder16 can have an indium (In), tin (Sn), silver (Ag) and copper (Cu) composition with at least about 40% indium, less than about 55% tin, and the balance being about 3% to 5% silver and 0.25% to 0.75% copper, by weight. Some embodiments ofsolder16 can have at least about 50% indium and about 45% or less tin. For example,solder16 can have a composition of more than 50% indium, a maximum of about 30% tin, about 3% to 5% silver and about 0.25% to 0.75% copper. In one embodiment,solder16 can be about 65% indium, about 30% tin, about 4.5% silver and about 0.5% copper, by weight. The indium content can even be higher than 65%, thereby further reducing the percentage of tin. An example of a suitable solder composition forsolder16 is disclosed in U.S. Pat. No. 6,253,988, issued Jul. 3, 2001, the entire teachings of which are incorporated herein by reference. The multilayer solder article can be formed with the desired solder compositions, and then, if desired, formed into electrical devices orelectrical connectors40.Solder13 andsolder16 can both include silver to prevent or reduce the scavenging of silver from theautomobile glass42.

Referring to FIGS.7 and8, when solderingelectrical device40 toautomotive glass42, asoldering device54 can apply a selected or programmed amount ofheat56 for soldering theelectrical device40 to theterminal pad44 of theautomotive glass42. Thesoldering device54 can be microprocessor controlled and the amount of required heat can be preselected or preprogrammed, for example in watt/sec. Such a soldering device is commercially available from Antaya Technologies Corporation, in Cranston, R.I. The programmed amount ofheat56 can melt the second or lowermelting temperature solder16 for soldering theelectrical device40 to theglass42 without substantially melting the first or highermelting temperature solder13. Preferably, the first or highermelting temperature solder13 does not melt at all, but slight melting is permitted, as long as there is not too much mixing of the two layers of

solder

13 and16. If the tin content next to theglass42 increases too much by the migration of tin from the layer of thefirst solder13 into the layer of thesecond solder16, cracking of theglass42 can occur.

In one embodiment, themultilayer solder article24 and resulting electrical device orelectrical connector40 can have afirst solder13 having a composition of 95Sn 5Ag, and asecond solder16 having a composition of 65In 30Sn 4.5Ag 0.5Cu. The melting point or melting temperature (liquidus) of a 95Sn 5Agfirst solder13 is about 465° F. (241° C.), and the solidus is about 430° F. (221° C.). The melting point or melting temperature (liquidus) of a 65In 30Sn 4.5Ag 0.5Cusecond solder16 is about 250° F. (121° C.), and the solidus is about 245° F. (118° C.). As can be seen, the difference in melting temperatures between the 95Sn 5Agfirst solder13 and the 65In 30Sn 4.5Ag 0.5Cusecond solder16 can be about 215° F. Such a differential between the two melting temperatures can permit thesecond solder16 to be melted without substantially melting thefirst solder13. Whensolder13 has a composition of 95Sn 5Ag andsolder16 has a composition of 65In 30Sn 4.5Ag 0.5Cu, about 500 to 650 watt/sec ofheat56 can be a suitable range for melting thesecond solder16 but not thefirst solder13. The amount of heat that is applied can differ depending upon the size and thickness of theconnector portion38 and the volume ofsolder16. In other embodiments, about 650 to 750 watt/sec can be suitable.

By having thesecond solder16 with a melting temperature below about 310° F., for example about 250° F., soldering thesecond solder16 to theautomotive glass42 at such a low temperature can minimize thermal stress on theautomotive glass42. In addition, the extent of cooling that thesecond solder16 experiences while cooling from the melting temperature to room temperature (for example down to about 70° F.) can be as little as a 180° F. temperature drop. Therefore, the amount of thermal shrinkage experienced by thesecond solder16 can be kept to a minimum due to the small temperature drop, thereby minimizing the shrinkage differential between thesecond solder16 and theautomotive glass42.Automotive glass42 has a very low coefficient thermal expansion relative to solder16, and does not shrink as much assolder16 during cooling. Furthermore, by including a high indium content, thesolder16 can be ductile or soft enough to absorb thermal expansion differences between thesolder16 and theautomotive glass42 without cracking theglass42. One or more of these factors can allow thesecond solder16 to solder toautomotive glass42 without cracking theglass42.

In other embodiments, the melting temperatures of the first13 and second16 solders can vary depending upon the situation at hand and the compositions chosen. The melting temperature of thefirst solder13 can be lower than 465° F., for example, about 350° F., or can be higher, for example, above 500° F., and even as high as about 650° F. The melting temperature of the second solder can be below 250° F., for example, as low as 135° F., or can be higher than 310° F., for example 500° F. to 550° F. The compositions chosen for the first13 and second16 solders should have at least about a 100° F. difference in melting temperature to more easily enable the melting of thesecond solder16 without substantially melting thefirst solder13. It may be possible to have smaller differences in melting temperature depending upon the precision at which theheat56 can be delivered and the compositions employed.

It has been found through further testing that additional embodiments of thesecond solder16 can have a greater range of tin and indium and be compatible or suitable for soldering on automotive glass without cracking or spalling the glass. Additional embodiments of thesecond solder16 can have a composition with 55% or more tin (Sn) and 40% or less indium (In). The composition of thesecond solder16 can have less than 90% tin (Sn) and greater than 10% indium (In), which in comparison to a high tin solder such as 95 Sn 5 Ag, is lower tin and high indium. The balance can be about 1% to 10% silver (Ag) (often about 1% to 6%), and about 0.25% to 0.75% copper (Cu). Embodiments of thesecond solder16 can have a melting temperature at about 360° F. and below, and often about 320° F. and below. In some embodiments, the melting temperature can be below about 315° F. and in other embodiments, can be below about 310° F.

In one embodiment, thesecond solder16 can be about 60% tin (Sn), about 35% indium (In), about 4.5% silver (Ag) and about 0.5% copper (Cu). The exact percentages can vary slightly due to normal variations in manufacturing, for example, about 59% to 61% Sn, about 34% to 36% In, about 4% to 5% Ag and about 0.4% to 0.6% Cu. The melting point or melting temperature (liquidus) can be about 300° F. (149° C.) and the solidus can be about 235° F. (113° C.). In another embodiment, thesecond solder16 can be about 50% Sn, about 46% In, about 3.5% Ag and about 0.5% Cu. The exact percentages can vary slightly due to normal variations in manufacturing, for example, about 49% to 52% Sn, about 45% to 47% In, about 3% to 4% Ag and about 0.4% to 0.6% Cu. The melting point or melting temperature (liquidus) can be about 240° F. (116° C.) and the solidus can be about 235° F. (113° C.). These compositions of thesecond solder16 can be used with afirst solder13 having 95 Sn 5 Ag, as well as other suitable compositions, including those previously described.

A common composition range of the additional embodiments of thesecond solder16 can be at least about 50% tin, at least about 10% indium, 1% to 10% silver (often about 2% to 6%), and about 0.25% to 0.75% copper. In some situations, it is understood that further elements can also be included in thesecond solder16 composition in addition to the tin, indium, silver and copper, typically, a relatively small percentage in comparison to the tin and indium.

The present invention also provides another non-lead solder composition that can be alone suitable for soldering electrical components to automotive glass for electrically connecting to electrical devices within or on the glass, as well as suitable for use as thesecond solder16 of a multilayer solder. Referring toFIG. 9, the rearautomotive glass window60 of an automobile is employed as an illustrative example for soldering electrical components to automotive glass.Automotive glass window60 can include awindow defroster62 consisting of electricallyresistive defrosting lines64 embedded within or deposited on the inner surface ofwindow60. The defrosting lines64 can be electrically connected to a pair ofelectrical contacts66 located on the inner surface of theglass60. Theelectrical contacts66 can consist of a conductive coating deposited on the inner surface of theglass60. Often,electrical contacts66 are formed from silver.

Referring toFIG. 10, thesolder composition70 can be employed to solder anelectrical connector72 to eachelectrical contact66 on theglass60.Power lines74 can then be electrically connected toelectrical connectors72 to provide power to window defroster62 (FIG. 9). Soldering of theelectrical connectors72 to theelectrical contacts66 onglass60 withsolder composition70 can be conducted by resistance soldering. Alternatively, any conventional soldering apparatus can be employed to meltsolder composition70, for example, a soldering iron.

Solder composition

70 can include tin (Sn), indium (In), silver (Ag), and bismuth (Bi).Solder composition70 can have a lower amount of tin than found in common high tin solder compositions. This can help prevent cracking and/or spalling ofautomotive glass60 during soldering. Sufficient indium can providesolder composition70 with a relatively low melting point or temperature (liquidus) as well as mechanical properties which can prevent cracking and/or spalling ofautomotive glass60.

Although too much bismuth can makesolder composition70 brittle, the proper amount of bismuth in combination with the other elements can providesolder composition70 with a sufficiently low solidus temperature that also can help prevent cracking and/or spalling ofautomotive glass60, without makingsolder composition70 too brittle. The bismuth can provide a paste range between the liquidus and solidus temperatures which can be as small as about 30° F. and as large as about 140° F. A proper amount of bismuth can keep the solidus temperature below about 330° F., commonly below about 315° F. Some embodiments of thesolder composition70 can have a solidus temperature of about 310° F. and less, for example, about 305° F. and less. The silver insolder composition70 can preventsolder composition70 from scavenging silver from theelectrical contact66 into thesolder composition70. Finally, copper (Cu) can be included withinsolder composition70 for improving wetting.

By providing thesolder composition70 with a relatively low melting temperature, thermal stress on theautomotive glass60 can be minimized. In addition, by providing the solder composition with a relatively low solidus temperature, the extent of cooling that thesolder composition70 experiences while cooling from the solidus temperature to room temperature can be minimized. Therefore, the amount of thermal shrinkage experienced by thesolder composition70 after solidification can be kept to a minimum due to a relatively small temperature drop, thereby minimizing the shrinkage differential and stresses between thesolder composition70 and theautomotive glass60. As previously mentioned, by including sufficient indium content, thesolder composition70 can be ductile or soft enough to absorb thermal expansion differences between thesolder composition70 and theautomotive glass60 without cracking and/or spalling theglass60.

A common compositional range forsolder composition70 can be about 30% to 85% tin, about 13% to 65% indium (often about 15% to 65%), about 1% to 10% silver, and about 0.25% to 6% bismuth, by weight. Some embodiments can include about 50% to 85% tin (often about 50% to 83%), and about 13% to 45% indium (often about 15% to 45%). Additional embodiments can include about 66% to 85% tin (often about 66% to 83%), and about 13% to 26% indium (often about 15% to 26%). Particular embodiments can include about 70% to 80% tin, and about 15% to 26% indium. Further embodiments can include copper, for example 0.25% to 0.75%. In some embodiments there can be about 1% to 6% silver, about 0.25% to 4% bismuth and about 0.25% to 0.75% copper.

To makesolder composition70, ingots of indium, tin, silver, bismuth and copper can be melted and mixed together. Alternatively, the elements can be melted from powder form or a desired combination of ingots, powder and/or existing solder compositions. Themixed solder composition70 can then be cast, extruded or rolled into a shape suitable for soldering, for example, a ribbon, wire, etc. If desired, thesolder composition70 can be formed into a paste.

In one embodiment,solder composition70 can include about 51% tin, about 42% indium, about 3.5% silver, about 3% bismuth and about 0.5% copper. The actual percentages can vary slightly due to normal variations in manufacturing, for example about 49% to 52% tin, about 40% to 44% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. The melting point or temperature (liquidus) can be about 253° F. (123° C.) and the solidus can be about 223° F. (106° C.), resulting in a paste range of about 30° F.

In another embodiment, thesolder composition70 can include about 60% to 63% tin, about 28% to 33% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. For example,solder composition70 can include about 62% tin, about 30% indium, about 5% silver, about 2.5% bismuth, and about 0.5% copper. The melting point or temperature (liquidus) can be about 311° F. (155° C.) and the solidus can be about 226° F. (108° C.), resulting in a paste range of about 85° F. In another example, thesolder composition70 can include about 62% tin, about 32% indium, about 4.5% silver, about 1% bismuth and about 0.5% copper. The melting point or temperature (liquidus) can be about 336° F. (169° C.) and the solidus can be about 199° F. (93° C.), resulting in a paste range of about 137° F. The coefficient of thermal expansion (CTE) can be about 11×10⁻⁶/° F. (19.7×10⁻⁶/° C.).

In still another embodiment, thesolder composition70 can include about 68% tin, about 24% indium, about 6% silver, about 1.5% bismuth and about 0.5% copper. The actual percentages can vary slightly, for example, about 66% to 69% tin, about 22% to 26% indium, about 1% to 7% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. The melting point or temperature (liquidus) can be about 360° F. (182° C.) and the solidus can be about 235° F. (113° C.), resulting in a paste range of about 125° F. The coefficient of thermal expansion (CTE) can be about 10.9×10⁻⁶/° F. (19.6×10⁻⁶/° C.).

In another embodiment, thesolder composition70 can include about 70% to 74% tin, about 18% to 26% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. For example, thesolder composition70 can include about 72% tin, about 19% indium, about 5% silver, about 3.5% bismuth and about 0.5% copper. The melting point or temperature (liquidus) can be about 370° F. (188° C.) and the solidus can be about 273° F. (134° C.), resulting in a paste range of about 97° F. The coefficient of thermal expansion (CTE) can be about 10.8×10⁻⁶/° F. (19.5×10⁻⁶/° C.). In another example, thesolder composition70 can include about 72% tin, about 24% indium, about 2% silver, about 1.5% bismuth and about 0.5% copper.

In another embodiment, thesolder composition70 can include about 73% to 78% tin, about 17% to 22% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. For example,solder composition70 can include about 75% tin, about 19% indium, about 3.5% silver, about 2% bismuth and about 0.5% copper. The melting point or temperature (liquidus) can be about 381° F. (194° C.) and the solidus can be about 284° F. (140° C.), resulting in a paste range of about 97° F. The coefficient of thermal expansion (CTE) can be about 10×10⁻⁶/° F. (18×10⁻⁶/° C.) and the density can be about 7.4 g/cm³. In another example, thesolder composition70 can include about 75% tin, about 20.5% indium, about 2.5% silver, about 1.5% bismuth and about 0.5% copper. The melting point or temperature (liquidus) can be about 372° F. (189° C.) and the solidus can be about 278° F. (137° C.), resulting in a paste range of about 94° F. In another example, thesolder composition70 can include about 77% tin, about 18% indium, about 3% silver, about 1.5% bismuth and about 0.5% copper. The melting point or temperature (liquidus) can be about 379° F. (193° C.) and the solidus can be about 297° F. (147° C.), resulting in a paste range of about 82° F. The coefficient of thermal expansion (CTE) can be about 8.8×10⁻⁶/° F. (15.9×10⁻⁶/° C.).

In another embodiment, thesolder composition70 can include about 78% to 85% tin, about 13% to 16% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper. For example,solder composition70 can include about 80% tin, about 15% indium, about 3.5% silver, about 1% bismuth and about 0.5% copper. The melting point or temperature (liquidus) can be about 390° F. (199° C.) and the solidus can be about 304° F. (151° C.), resulting in a paste range of about 86° F. The coefficient of thermal expansion (CTE) can be about 8.5×10⁻⁶/° F. (15.3×10⁻⁶/° C.). In another example, thesolder composition70 can also include about 83% tin, about 13% indium, about 2.5% silver, about 1% bismuth, and about 0.5% copper. The melting point or temperature (liquidus) can be about 399° F. (204° C.) and the solidus can be about 305° F. (152° C.), resulting in a paste range of about 94° F. The coefficient of thermal expansion (CTE) can be about 7.6×10⁻⁶/° F. (13.7×10⁻⁶/° C.). In some situations, the indium content can be about 12% to 16%.

While this invention has been particularly shown and described with references to particular embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

For example, theapparatus10 can be employed for bonding more than two layers of solder together, resulting in a multilayer solder article, electrical device or electrical connector having more than two layers of solder. In addition, the mating surfaces of thesolders13/16 can be pretreated for bonding purposes. In embodiments where the multilayer solder article does not have abase substrate11, the multilayer solder article can be subsequently bonded or positioned relative to products requiring soldering. A rolling process can also be used to bond thefirst solder13 to thebase substrate11. Althoughmultilayer solder article24 has been shown and described to be formed employing cold rolling processes, alternatively,article24 and/or electrical device orconnector40 can be formed employing other processes, for example, deposition or reflow processes. Ultrasonic or resistance welding devices can also be employed for bonding desired layers of material together. For example, the solders can be applied to thebase substrate11 by welding processes. Although particular solder compositions have been described for the first13 and second16 solders, alternatively other solder compositions can be employed for various applications, including compositions containing lead. Embodiments of the apparatuses and resulting articles, electrical devices, electrical connectors shown and described, can also be for non automotive applications. Thefirst solder layer13 can be used to compensate for uneven surfaces and can be omitted when very flat surfaces are encountered.

Although particular solder compositions have been described for soldering to automotive glass, alternatively, the solder compositions can be employed for soldering to other types of glass such as used in buildings or any other material where a low melting or solidus point solder is desirable. In addition, although particular solidus and liquidus temperatures have been given, such temperatures can vary depending upon the elements present and the percentages of those elements. Furthermore, in some embodiments, additional elements may be added to the solder compositions or substituted for elements in the solder compositions, for example, antimony, zinc, nickel, iron, gallium, germanium, cadmium, titanium, tellurium, platinum, etc.

Claims

1. A solder composition having a mixture of elements comprising tin, indium, silver, and bismuth, and including about 30% to 85% tin and about 15% to 65% indium.

2. The solder composition ofclaim 1 further comprising copper.

3. The solder composition ofclaim 2 in which the composition includes about 1% to 10% silver, about 0.25% to 6% bismuth, and about 0.25% to 0.75% copper.

4. The solder composition ofclaim 3 in which the composition includes about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

5. The solder composition ofclaim 1 in which the composition includes about 50% to 83% tin.

6. The solder composition ofclaim 5 in which the composition includes about 15% to 45% indium.

7. The solder composition ofclaim 1 in which the composition has a solidus temperature below about 315° F.

8. A solder composition having a mixture of elements comprising tin, indium, silver, and bismuth, and including about 30% to 85% tin, about 13% to 65% indium, and about 0.25% to 4% bismuth.

9. The solder composition ofclaim 8 further comprising copper.

10. The solder composition ofclaim 9 in which the composition includes about 1% to 10% silver, and about 0.25% to 0.75% copper.

11. The solder composition ofclaim 10 in which the composition includes about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

12. The solder composition ofclaim 8 in which the composition includes about 50% to 83% tin.

13. The solder composition ofclaim 12 in which the composition includes about 13% to 45% indium.

14. The solder composition ofclaim 12 in which the composition includes about 15% to 45% indium.

15. The solder composition ofclaim 8 in which the composition has a solidus temperature below about 315° F.

16. A solder composition having a mixture of elements comprising tin, indium, silver, bismuth and copper, and including about 30% to 85% tin and about 13% to 65% indium.

17. The solder composition ofclaim 16 in which the composition includes about 1% to 10% silver, about 0.25% to 6% bismuth, and about 0.25% to 0.75% copper.

18. The solder composition ofclaim 17 in which the composition includes about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

19. The solder composition ofclaim 16 in which the composition includes about 50% to 83% tin.

20. The solder composition ofclaim 19 in which the composition includes about 13% to 45% indium.

21. The solder composition ofclaim 20 in which the composition includes about 15% to 45% indium.

22. The solder composition ofclaim 18 in which the composition comprises about 66% to 85% tin, and about 13% to 26% indium.

23. The solder composition ofclaim 16 in which the composition has a solidus temperature below about 315° F.

24. The solder composition ofclaim 16 in which the composition comprises about 70% to 80% tin, and about 15% to 26% indium.

25. The solder composition ofclaim 16 in which the composition comprises about 70% to 74% tin, about 18% to 26% indium, about 1% to 6% silver, about 0.25% to 4% bismuth and about 0.25% to 0.75% copper.

26. The solder composition ofclaim 16 in which the composition comprises about 73% to 78% tin, about 17% to 22% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

27. The solder composition ofclaim 16 in which the composition comprises about 78% to 85% tin, about 13% to 16% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

28. A solder composition comprising tin, indium and silver, and including more than about 60% tin, the composition having a solidus temperature below about 330° F.

29. The solder composition ofclaim 28 in which the solidus temperature is below about 315° F.

30. The solder composition ofclaim 29 further comprising bismuth.

31. The solder composition ofclaim 30 further comprising copper.

32. A method of forming a solder composition comprising mixing tin, indium, silver, and bismuth together, and including about 30% to 85% tin and about 15% to 65% indium.

33. The method ofclaim 32 further comprising mixing copper.

34. The method ofclaim 33 further comprising mixing about 1% to 10% silver, about 0.25% to 6% bismuth, and about 0.25% to 0.75% copper.

35. The method ofclaim 34 further comprising mixing about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

36. The method ofclaim 32 further comprising mixing about 50% to 83% tin.

37. The method ofclaim 36 further comprising mixing about 15% to 45% indium.

38. The method ofclaim 32 further comprising providing the composition with a solidus temperature below about 315° F.

39. A method of forming a solder composition comprising mixing tin, indium, silver, and bismuth together, and including about 30% to 85% tin, about 13% to 65% indium, and about 0.25% to 4% bismuth.

40. The method ofclaim 39 further comprising mixing copper.

41. The method ofclaim 40 further comprising mixing about 1% to 10% silver, and about 0.25% to 0.75% copper.

42. The method ofclaim 41 further comprising mixing about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

43. The method ofclaim 39 further comprising mixing about 50% to 83% tin.

44. The method ofclaim 42 further comprising mixing about 13% to 45% indium.

45. The method ofclaim 43 further comprising mixing about 15% to 45% indium.

46. The method ofclaim 39 further comprising providing the composition with a solidus temperature below about 315° F.

47. A method of forming a solder composition comprising mixing tin, indium, silver, bismuth and copper together, and including about 30% to 85% tin and about 13% to 65% indium.

48. The method ofclaim 47 further comprising mixing about 1% to 10% silver, about 0.25% to 6% bismuth, and about 0.25% to 0.75% copper.

49. The method ofclaim 48 further comprising mixing about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

50. The method ofclaim 47 further comprising mixing about 50% to 83% tin.

51. The method ofclaim 50 further comprising mixing about 13% to 45% indium.

52. The method ofclaim 51 further comprising mixing about 15% to 45% indium.

53. The method ofclaim 49 further comprising mixing about 66% to 85% tin and about 13% to 26% indium.

54. The method ofclaim 47 further comprising providing the composition with a solidus temperature below about 315° F.

55. The method ofclaim 47 further comprising mixing about 70% to 80% tin, and about 15% to 26% indium.

56. The method ofclaim 47 further comprising mixing about 70% to 74% tin, about 18% to 26% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

57. The method ofclaim 47 further comprising mixing about 73% to 78% tin, about 17% to 22% indium, about 1% to 6% silver, about 0.25% to 4% bismuth, and about 0.25% to 0.75% copper.

58. The method ofclaim 47 further comprising mixing about 78% to 85% tin, about 13% to 16% indium, about 1% to 6% silver, about 0.25 to 4% bismuth, and about 0.25% to 0.75% copper.

59. A method forming a solder composition comprising mixing tin, indium and silver together, including more than about 60% tin, and providing the composition with a solidus temperature below about 330° F.

60. The method ofclaim 59 further comprising providing a solidus temperature below about 315° F.

61. The method ofclaim 60 further comprising mixing bismuth.

62. The method ofclaim 61 further comprising mixing copper.

63. A method of soldering comprising:

providing a solder composition having a mixture of elements comprising tin, indium, silver, and bismuth, and including about 30% to 85% tin and about 15% to 65% indium; and

melting the solder composition with a soldering device.