Abstract:
A lead-free solder alloy consisting essentially of, by weight, 3.0% to 3.5% silver, greater than 1% to about 15% copper, the balance tin and incidental impurities, and having an effective melting range of about 215°C to about 222°C. The solder alloy is noneutectic, and therefore characterized by solidus and liquidus temperatures, the former being in a range of about 215°C to about 218°C, while the latter is about 290°C or more. However, the melting mechanism exhibited by the alloy is such that the alloy is substantially all melted and does not exhibit a "mushy zone" above the effective melting range, enabling the alloy to behave similarly to the SnAgCu eutectic alloy
Abstract:
A lead-free solder alloy suitable for forming solder joints of a surface-mount integrated circuit device, such as a flip chip. The solder alloy has a sufficiently low liquidus temperature to achieve desirable reflow properties at temperatures of 240°C and less, and is therefore compatible with integrated circuit processes. The solder alloy has a sufficiently high solidus temperature to ensure that solder joints formed with the alloy exhibit suitable mechanical properties at application temperatures up to 150°C when mounting a component to a laminate substrate. The solder alloy generally contains, in weight percent, about 7 to about 11% indium, about 2.5 to about 3.5% silver, and about 0.5 to about 1.5% copper, the balance tin and incidental impurities.
Abstract:
An improved vertical integrated circuit device package (10) that eliminates or reduces the need for wire bond connections and/or solder connections is provided. The package includes a vertical device (14) having electrodes (20,21) on opposite surfaces, and a compressed spring member (12c) that is used to establish compression electrical connections between the electrodes (20) and corresponding electrically conductive elements (24).
Abstract:
A method by which semiconductor wafers (10, 12) can be solder bonded to form a semiconductor device, such as a sensor with a micromachined structure (14). The method entails forming a solderable ring (18) on the mating surface of a device wafer (10), such that the solderable ring (18) circumscribes the micromachine (14) on the wafer (10). A solderable layer (20, 26, 28) is formed on a capping wafer (12), such that at least the mating surface (24) of the capping wafer (12) is entirely covered by the solderable layer (20, 26, 28). The solderable layer (20, 26, 28) can be formed by etching the mating surface (24) of the capping wafer (12) to form a recess (16) circumscribed by the mating surface (24), and then forming the solderable layer (26) to cover the mating surface (24) and the recess (16) of the capping wafer (12). Alternatively, the solderable layer (28) can be formed by depositing a solderable material to cover the entire lower surface of the capping wafer (12), patterning the resulting solderable layer (28) to form an etch mask on the capping wafer (12), and then to form the recess (16), such that the solderable layer (28) covers the mating surface (24) but not the surfaces of the recess (16).
Abstract:
A tin-lead solder alloy containing copper and/or nickel and optionally silver, palladium, platinum and/or gold as its alloying constituents. The solder alloy consists essentially of, by weight, about 5% to about 70 % tin, up to about 4% silver palladium, platinum and/or gold, about 0.5 % to about 10% copper and/or nickel, the balance lead and incidental impurities. The presence of copper and/or nickel in the alloy has the beneficial effect of inhibiting the dissolution and leaching of silver from a silver-containing thick-film, such as a conductor (18) or solder pad (16), into the molten solder alloy during reflow. In addition, solder joints (22) formed of the solder alloy form a diffusion barrier layer (24,26) of intermetallic compounds that inhibit solid-state interdiffusion between silver from a silver-containing thick-film (16,18) and tin from the solder joint (22).
Abstract:
A tin-lead solder alloy containing copper and optionally silver as its alloying constituents. The solder alloy consists essentially of, by weight, about 55% to about 75% tin, about 11% to about 44% lead, up to about 4% silver, nickel, palladium, platinum and/or gold, greater than 1% to about 10% copper, and incidental impurities. The solder alloys contain a small portion of CuSn intermetallic compounds, and exhibit a melting mechanism in which all but the intermetallic compounds melt within a narrow temperature range, though the actual liquidus temperature of the alloys may be considerably higher, such that the alloys can be treated as requiring peak reflow temperatures of about 250°C or less. The intermetallic compounds precipitate out to form a diffusion barrier that increases the reliability of solder connections formed therewith.
Abstract:
A system (10) and method (300) for supporting an electronic component (12) attached to a circuit board (14). solder paste (40) is applied to a solder pad (16) underneath and aligned with a non-wetting region (18) of an electronic component (12) to form a support (34) formed of solder to prevent electronic component (12) lead (26) flexing. The amount of solder for forming the support (34) and the size of the solder pad (16) are selected to bring the support (34) into contact with, or in close proximity to, the non-wetting region (18).
Abstract:
A liquid metal rotary connector (16) for a vehicle steering mechanism (10) utilizes a conductive alloy comprising Gallium, Indium, Tin and Zinc to electrically couple stationary and rotary terminals (26a, 26b; 28a, 28b) of the connector (16). The alloy is a liquid at ambient temperatures, and has a melting point of -36°C, though testing has shown that it operates satisfactorily at temperatures as low as -40°C. In a preferred arrangement, the rotary connector (16) provides a two-wire connection through which power is supplied from the steering column (12) to the steering wheel (14), and electronic modules (22, 24) located in the steering column (12) and the steering wheel (14) support bi-directional data communication through voltage and current modulation of the supplied power.