A solder preform in the shape of a solder tube or washer includes: a cylindrically shaped solder alloy body including an inner surface, an outer surface, a first end, a second end, a first opening located at the first end, and a second opening located at the second end, the second end interlocking with the first end, and the first opening and the second opening cut along an entire height of the solder alloy body; and a flux core embedded in the solder alloy body between the inner surface and the outer surface, the flux core including a thermochromic indicator. During reflow soldering, the flux core including the thermochromic indicator flows out of the first opening of the first end and the second opening of the second end to coat the inner surface of the solder alloy body and the outer surface of the solder alloy body.

A solder alloy essentially consists of tin, silver, copper, bismuth, antimony, and cobalt. Relative to a total amount of the solder alloy, the silver content is 2 mass % or more and 4 mass % or less, the copper content is 0.3 mass % or more and 1 mass % or less, the bismuth content is more than 4.8 mass % and 10 mass % or less, the antimony content is 3 mass % or more and 10 mass % or less, the cobalt content is 0.001 mass % or more and 0.3 mass % or less, and the tin content is the remaining portion.

A solder alloy essentially consists of tin, silver, copper, bismuth, antimony, and cobalt. Relative to a total amount of the solder alloy, the silver content is 2 mass % or more and 4 mass % or less, the copper content is 0.3 mass % or more and 1 mass % or less, the bismuth content is more than 4.8 mass % and 10 mass % or less, the antimony content is 3 mass % or more and 10 mass % or less, the cobalt content is 0.001 mass % or more and 0.3 mass % or less, and the tin content is the remaining portion.

A solder composition for use in solder joints of printed circuit boards (PCBs), including a compound layer comprising an alloy of bismuth and tin; and a graphene coating positioned on the compound layer.

A solder paste including metal powders, constituted by an alloy powder including bismuth and silver, and a tin powder, the alloy powder including bismuth and silver including silver at a ratio of greater than or equal to 0.1 wt % and less than or equal to 11.0 wt % is provided.

Embodiments describe high aspect ratio and fine pitch interconnects for a semiconductor package, such as a package-on-package structure. In an embodiment, the interconnects are formed with a no-slump solder paste. In an embodiment, the no-slump solder paste is printed in an uncured state, and is then cured with a liquid phase sintering process. After being cured, the no-slump solder paste will not reflow at typical processing temperatures, such as those below approximately 400° C. According to embodiments, the no-slump solder paste includes Cu particles or spheres, a solder matrix component, a polymeric delivery vehicle, and a solvent. In an embodiment, the liquid phase sintering produces a shell of intermetallic compounds around the Cu spheres. In an embodiment, the sintering process builds a conductive metallic network through the no-slump solder paste.

Embodiments describe high aspect ratio and fine pitch interconnects for a semiconductor package, such as a package-on-package structure. In an embodiment, the interconnects are formed with a no-slump solder paste. In an embodiment, the no-slump solder paste is printed in an uncured state, and is then cured with a liquid phase sintering process. After being cured, the no-slump solder paste will not reflow at typical processing temperatures, such as those below approximately 400° C. According to embodiments, the no-slump solder paste includes Cu particles or spheres, a solder matrix component, a polymeric delivery vehicle, and a solvent. In an embodiment, the liquid phase sintering produces a shell of intermetallic compounds around the Cu spheres. In an embodiment, the sintering process builds a conductive metallic network through the no-slump solder paste.

One aspect of the disclosure provides an iron-based hardfacing layer which includes hard or wear resistant phases resulting at least in part from dissolution of silicon and/or boron carbide particles into a liquid iron-based metal during the fabrication process. In an embodiment, the hardfacing layer is formed by a fusion welding process in which carbide particles are added to the molten weld pool. In an example, the filler metal supplied to the welding process is a mild steel. In an embodiment, the hardness as measured at the surface of the hardfacing ranges from 40 to 65 HRC. In an example, the iron-based hardfacing layer also includes tungsten carbide particles.

Some embodiments relate to a semiconductor device package, which includes a substrate with a contact pad. A non-solder ball is coupled to the contact pad at a contact pad interface surface. A layer of solder is disposed over an outer surface of the non-solder ball, and has an inner surface and an outer surface which are generally concentric with the outer surface of the non-solder ball. An intermediate layer separates the non-solder ball and the layer of solder. The intermediate layer is distinct in composition from both the non-solder ball and the layer of solder. Sidewalls of the layer of solder are curved or sphere-like and terminate at a planar surface, which is disposed at a maximum height of the layer of solder as measured from the contact pad interface surface.

Some embodiments relate to a semiconductor device package, which includes a substrate with a contact pad. A non-solder ball is coupled to the contact pad at a contact pad interface surface. A layer of solder is disposed over an outer surface of the non-solder ball, and has an inner surface and an outer surface which are generally concentric with the outer surface of the non-solder ball. An intermediate layer separates the non-solder ball and the layer of solder. The intermediate layer is distinct in composition from both the non-solder ball and the layer of solder. Sidewalls of the layer of solder are curved or sphere-like and terminate at a planar surface, which is disposed at a maximum height of the layer of solder as measured from the contact pad interface surface.