Abstract: The object of this invention is to employ a solder alloy comprising tin/lead/silver in order to provide a wider solidification range and achieve balance between the surface tensions of both side of a small leadless component. The expanded solidification range slows the melting and wetting time so as to balance the surface tension of the molten solder, and in turn reduces the tombstoning frequency. The preferred Ag concentration is 0.2-0.5% in weight, the more preferred Ag concentration is 0.3-0.4% in weight. For reflow soldering of small leadless components, the pastes made with the alloy compositions of Sn62.6Pb37Ag0.4 and Sn63Pb36.6Ag0.4 results in improvements in tombstoning.

Abstract: A high lead solder exhibiting improved wettability to metal substrates, an advantageously controlled melting range, and excellent thermal fatigue properties. It comprises about 98-100% lead and a minor amount, typically about 0.0005-0.1 wt %, based on the total weight of the solder composition, of an alkali metal selected from the group consisting of Na, K, and Li. Additional embodiments additionally comprise an amount of a grain-size controlling additive, e.g., 0.001-0.5 wt % (based on the total weight of all the components in the solder composition) selected from the group consisting of Ce, Ba, La, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, Y, Lu, Sc, Mg, Na, Se, Te, oxides thereof and mixtures thereof, in amount effective to control the Pb grain size; and 0-1 wt % of an element selected from the group consisting of Sn, In, Bi, Sb, Ag, Au, and Ga, and mixtures thereof.

Abstract: An integrated solder preform array is composed of a metal or metal alloy suitable for use in a soldering or bonding process. The preform includes a series of discrete solder islands disposed in a desired matrix. Each island contains a hole for receiving a pin, and bridging strands for joining each of said islands in a matrix. The bridging strands are formed of the same solder material as the islands, with the solder preform containing a substantially uniform coating of tin over its entire outer surface for the purpose of improving solder wetting and therefore elimination of unwanted shorting of circuits and other electrical components being soldered.

Abstract: An integral solder preform is disclosed for application to a printed circuit card having first and second sides, a first edge and first and second pluralities of conductive pads disposed on the respective first and second sides of the printed circuit card in respective first and second predetermined conductive pad arrangements. The integral solder preform has first and second pluralites of solder pads having respective first and second solder pad arrangements which are maintained in position by a plurality of bridging solder bands. The first and second solder pad arrangements correspond to the first and second predetermined conductive pad arrangements and are spaced apart by a predetermined distance by spacing solder bands.

Abstract: A low melting point solder alloy comprising effective amounts of tin, silver and indium.

Abstract: A lead-free alloy suitable for soldering comprising from about 82% to about 90% tin, from about 4.5% to about 6% zinc, from about 3.5% to about 6% indium and from about 1% to about 5% bismuth. The melting temperature of the alloy is preferably below 190.degree. C. and the alloy preferably has a pasty range of less than 10.degree. C.

Abstract: A low melting point solder alloy comprising effective amounts of tin, silver and indium.

Abstract: An alloy composition comprising effective amounts of bismuth, indium, lead, tin, and gallium, which is especially suited for lens blocking.

Abstract: A low melting point solder alloy comprising effective amounts of tin, zinc and indium.

Abstract: A solder preform containing a series of islands that are joined together in a matrix by bridging bands. Each band has a reduced cross-sectional area in its midregion. In one form of this invention, at least some of the islands contain pin receiving holes formed therein and solder tabs that are arranged to frictionally engage a pin that is passed into the hole to prevent the preform from being misaligned or dislodged from the pins and which at the time of bonding, prewets the pins to promote flowing of solder to the pins from the islands to form a superior solder joint.

Abstract: Indium-containing feedstocks, such as flue dusts from a refining or smelting process, are treated to increase the concentration of indium and at the same time to reduce the concentrations of lead, copper, and arsenic. The flue dusts are treated in a sodium-doped lead bath at temperatures of 675.degree. to 800.degree. C. Soda ash in the amount of 15 to 35 weight percent is blended with the feed stock and added to the sodium-doped lead bullion. The sodium reacts with the dusts to form a liquid dross, which is removed, cooled, and crushed. The powdered dross is water leached to remove the sodium salts. The indium remains in the filler cake and can be processed by conventional methods for the recovery of indium. About 95% of the indium reports to the filter cake, while lead retention in the filter cake is only about 5-15% of the initial lead content in the dust. A majority of the zinc also reports to the filter cake.

Abstract: An indium-metal braid-indium sandwich is formed by applying indium ribbons to upper and lower surfaces of a metal braid and then working the sandwich, e.g., between rollers. The resulting product has enhanced tensile strength and stiffness, yet retains the attributes of indium for application as a gasket, gland, or seal.

Abstract: An indium-metal braid-indium sandwich is formed by applying indium ribbons to upper and lower surfaces of a metal braid and then working the sandwich, e.g., between rollers. The resulting product has enhanced tensile strength and stiffness, yet retains the attributes of indium for application as a gasket, gland, or seal.

Abstract: A method and apparatus for ultrapurification of indium and other metals having a wide liquid range and low vapor pressure. The purification method involves producing a small-diameter stream of liquified metal, directing this stream along a predetermined path while subjecting it to a high vacuum and heating it to vaporize volatile impurities, then collecting and solidifying the purified stream. The method is optimally practiced in the ultrahigh vacuum and substantially zero gravity environment of outer space. Apparatus for practicing the method in outer space employs a containerless refining zone in which the stream of liquid metal being purified is directed along a path defined by edges of thin guides fabricated of material which is not substantially wetted by the liquid metal. Heating of the liquid metal stream is accomplished via RF coils surrounding the guides defining the stream path. Upon collection, the purified metal stream may be further subjected to a secondary refining process.

Abstract: A process for manufacturing combination covers for closing and sealing an electronic package that includes a ceramic lid having a noble metal base frame thick-filmed onto the lid and fired therewith to fuse the base metal to the lid. A gold-tin solder frame is placed over the base frame and bonded thereto to complete the cover.

Abstract: A combination ceramic sealing cover for a semiconductor package has a flat ceramic lid member with metallization applied as a foundation for a seal ring or frame portion. On the metallized layer is a gold-tin solder layer, in the form of either a solder ring that is tack welded on, or solder paste that is screened onto the base metallization and furnace reflowed.

Abstract: A lid for closing an electronic package that exhibits high resistance to corrosion. The lid includes a metal substrate and a multi-layered protective coating which has low porosity when compared to a single layer coating of the same thickness yet has good soldering properties that enables the lid to be hermetically sealed to the package container. The multi-layer coating includes an initial electroplated layer of nickel followed by a thin interlayer of a noble metal and a second layer of nickel electroplated over noble metal. A top layer of gold is then electroplated over the nickel-noble metal-nickel sandwich to complete the lid structure.