This tin or tin alloy electroplating solution according to one aspect contains a soluble salt (A) including at least a stannous salt, one or more compounds (B) selected from the group consisting of an organic acid, an inorganic acid, and a salt thereof, a surfactant (C) that is a polyoxyethylene polycyclic phenyl ether sulfuric acid ester salt represented by the following General Formula (1), and a leveling agent (D).

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In General Formula (1), m is an integer of 1 to 3, n is an integer of 10 to 30, and X is a cation.

A stackable via package includes a substrate having an upper surface and a trace on the upper surface, the trace including a terminal. A solder ball is on the terminal. The solder ball has a solder ball diameter A and a solder ball height D. A via aperture is formed in a package body enclosing the solder ball to expose the solder ball. The via aperture includes a via bottom having a via bottom diameter B and a via bottom height C from the upper surface of the substrate, where A<B and 0=<C<1/2×D. The shape of the via aperture prevents solder deformation of the solder column formed from the solder ball as well as prevents solder bridging between adjacent solder columns.

Flexible electrical devices comprising electrode layers on softening polymers and methods of manufacturing such devices, including lift-off processes for forming electrodes on softening polymers, processes for forming devices with a patterned double softening polymer layer, and solder reflow processes for forming electrical contacts on softening polymers.

A circuit assembly with an electrical connection between two individual Printed Circuit Boards (PCBs) or Circuit Card Assemblies (CCAs) that are vertically stacked with a connection formed entirely of solder and with a gap in between surfaces that components may occupy. Coalescing solder paste merges between the surfaces when it is in a liquid state to form a solder bridge. The resultant assembly can be encapsulated to form a solid monolithic electronic assembly to improve robustness and allow the assembly to better withstand compressive forces.

Systems and methods for applying solder to a pin. The methods comprising: disposing a given amount of solder on a non-wetable surface of a planar substrate; aligning the pin with the solder disposed on the non-wetable surface of the planar substrate; inserting the pin in the solder; and/or performing a reflow process to cause the solder to transfer from the planar substrate to the pin.

A printed wiring board includes a base insulating layer, a conductor layer formed on the base insulating layer and including conductor pads, a solder resist layer formed on the base insulating layer such that the solder resist layer is covering the conductor layer and having openings exposing the conductor pads, respectively, and plating bumps formed on the conductor pads such that each of the plating bumps includes a base plating layer formed in a respective one of the openings of the solder resist layer, and a top plating layer formed on the base plating layer. The plating bumps are formed such that the base plating layer has an upper surface and a side surface including a portion protruding from the solder resist layer and having a rough surface and that the top plating layer has a hemispherical shape and is covering only the upper surface of the base plating layer.

Systems and methods for applying solder to a pin. The methods comprising: disposing a given amount of solder on a non-wetable surface of a planar substrate; aligning the pin with the solder disposed on the non-wetable surface of the planar substrate; inserting the pin in the solder; and performing a reflow process to cause the solder to transfer from the planar substrate to the pin.

A method for circuit fabrication includes defining a solder bump, including a specified solder material and having a specified bump volume, to be formed at a target location on an acceptor substrate. A transparent donor substrate, having a donor film including the specified solder material, is positioned such that the donor film is in proximity to the target location on the acceptor substrate. A sequence of pulses of laser radiation is directed to pass through the first surface of the donor substrate and impinge on the donor film so as to induce ejection from the donor film onto the target location on the acceptor substrate of a number of molten droplets of the solder material such that the droplets deposited at the target location cumulatively reach the specified bump volume. The target location is heated so the deposited droplets melt and reflow to form the solder bump.

A method of attaching a chip to the substrate with an outer layer comprising via pillars embedded in a dielectric such as solder mask, with ends of the via pillars flush with said dielectric, the method comprising the steps of: (o) optionally removing organic varnish, (p) positioning a chip having legs terminated with solder bumps in contact with exposed ends of the via pillars, and (q) applying heat to melt the solder bumps and to wet the ends of the vias with solder.

Examples are disclosed related to forming solder joints between printed circuits by using radiant heat. One example provides a method of manufacturing an electronic device, the method comprising aligning a contact of a first printed circuit with a via of a second printed circuit. The method further comprises applying radiant heat via an infrared light source to a second surface of the second printed circuit, the radiant heat incident on the via to cause the via to conduct heat to solder located at an interface of the contact and the via, and after heating the solder to reflow, cooling the solder, thereby forming a solder joint between the contact of the first printed circuit and the via of the second printed circuit.