The present invention relates to paste compositions comprising an indium metal powder; and an organic vehicle. The organic vehicle includes one or more C8-C18 fatty acids; a salt formed from a C4-C6 carboxylic acid and a tertiary alkanolamine; a cationic catalyst; a thixotrope; and a diluent.

The present invention relates to paste compositions comprising an indium metal powder; and an organic vehicle. The organic vehicle includes one or more C8-C18 fatty acids; a salt formed from a C4-C6 carboxylic acid and a tertiary alkanolamine; a cationic catalyst; a thixotrope; and a diluent.

Some implementations of the disclosure are directed to a thermal interface material. In some implementations, a method comprises: applying a solder paste between a surface of a heat generating device and a surface of a heat transferring device to form an assembly; and reflow soldering the assembly to form a solder composite, wherein the solder composite provides a thermal interface between the heat generating device and the heat transferring device, wherein the solder paste comprises: a solder powder; particles having a higher melting temperature than a soldering temperature of the solder paste, wherein the solder paste has a volume ratio of solder powder to high melting temperature particles between 5:1 and 1:1.5; and flux.

A lead-free solder alloy may comprise tin, silver, copper, bismuth, cobalt, and antimony. The alloy may further comprise nickel. The silver may be present in an amount from about 2.0% to 2.8% by weight of the solder. The copper may be present in an amount from about 0.2% to 1.2% by weight of the solder. The bismuth may be present in an amount from about 0.0% to about 5.0% by weight of the solder. In some embodiments, the bismuth may be present in an amount from about 1.5% to 3.2% by weight of the solder. The cobalt may be present in an amount from about 0.001% to about 0.2% by weight of the solder. The antimony may be present in an amount between about 0.0% to about 0.1% by weight of the solder. The balance of the solder is tin.

A solder alloy has an alloy composition consisting of, in mass %, Ag: 0 to 4%, Cu: 0.1 to 1.0%, Ni: 0.01 to 0.3%, Sb: 5.1 to 7.5%, Bi: 0.1 to 4.5%, Co: 0.001 to 0.3%, P: 0.001 to 0.2%, and the balance being Sn.

A solder alloy has an alloy composition consisting of, in mass %, Ag: 0 to 4%, Cu: 0.1 to 1.0%, Ni: 0.01 to 0.3%, Sb: 5.1 to 7.5%, Bi: 0.1 to 4.5%, Co: 0.001 to 0.3%, P: 0.001 to 0.2%, and the balance being Sn.

In a layered bonding material 10, a coefficient of linear expansion of a base material 11 is 5.5 to 15.5 ppm/K and a first surface and a second surface of the base material 11 are coated with pieces of lead-free solder 12a and 12b.

A flux comprising an organic acid; a solvent; and polyoxyethylene behenyl alcohol having an average number of moles of ethylene oxide added of 7 to 40 mol.

A lead-free solder ball is provided which suppresses interfacial peeling in a bonding interface of a solder ball, fusion defects which develop between the solder ball and solder paste, and which can be used both with Ni electrodes plated with Au or the like and Cu electrodes having a water-soluble preflux applied atop Cu. The lead-free solder ball for electrodes of BGAs or CSPs consists of 1.6-2.9 mass % of Ag, 0.7-0.8 mass % of Cu, 0.05-0.08 mass % of Ni, and a remainder of Sn. It has excellent resistance to thermal fatigue and to drop impacts regardless of the type of electrodes of a printed circuit board to which it is bonded, which are Cu electrodes or Ni electrodes having Au plating or Au/Pd plating as surface treatment.

A lead-free solder ball is provided which suppresses interfacial peeling in a bonding interface of a solder ball, fusion defects which develop between the solder ball and solder paste, and which can be used both with Ni electrodes plated with Au or the like and Cu electrodes having a water-soluble preflux applied atop Cu. The lead-free solder ball for electrodes of BGAs or CSPs consists of 1.6-2.9 mass % of Ag, 0.7-0.8 mass % of Cu, 0.05-0.08 mass % of Ni, and a remainder of Sn. It has excellent resistance to thermal fatigue and to drop impacts regardless of the type of electrodes of a printed circuit board to which it is bonded, which are Cu electrodes or Ni electrodes having Au plating or Au/Pd plating as surface treatment.