Abstract: Described herein are methods for forming welded connections to flexible interconnect circuits and assemblies comprising such connections. An assembly can include a flexible circuit and an electrical component subassembly. The flexible circuit may comprise a first insulating layer, a conductive layer, and a second insulating layer. The conductive layer may comprise aluminum and may be stacked between the first insulating layer and the second insulating layer. The electrical component subassembly may comprise an electrical component and an interconnecting structure. The electrical component may comprise a base, a contact pad comprising copper and stacked with the base, and a component opening extending through each of the base and the contact pad. The interconnecting structure may be stacked between the contact pad and the conductive layer. The interconnecting structure may be attached to the contact pad and be welded to the conductive layer by a weld plug.

Abstract: Described herein are methods for forming welded and soldered connections to flexible interconnect circuits and assemblies comprising such connections. An assembly can include a weldable transition unit having a transition pad and a solderable pad. The transition pad may comprise aluminum and can be welded to the aluminum conductive trace of a flexible interconnect circuit. The solderable pad can be soldered to the electrical contact of a device (e.g., a resistor, capacitor). In some examples, the weldable transition unit may comprise a stiffener mechanically connected to the transition pad to provide mechanical support of the transition pad and devices soldered to the transition pad. In some examples, the device soldered to the weldable transition unit may include one or more individual electronic components. In some examples, the device soldered to the weldable transition unit may be a printed circuit board (PCB) having solderable traces.

Abstract: The present invention relates to a process for eliminating low solder ball shear strength in electronic packages and interconnect substrates, and the resulting electronic package or interconnect substrates. In the present invention interconnect substrates are processed to provide a conductive surface contact with a layer of gold that forms a more substantial bond with a solder ball to increase the solder ball shear strength value, especially when the solder ball and corresponding conductive surface contact are electrically coupled to internal power and/or ground planes.