Microfeature workpieces having alloyed conductive structures, and associated methods are disclosed. A method in accordance with one embodiment includes applying a volume of material to a bond pad of a microfeature workpiece, with the volume of material including a first metallic constituent and the bond pad including a second constituent. The method can further include elevating a temperature of the volume of material while the volume of material is applied to the bond pad to alloy the first metallic constituent and the second metallic constituent so that the first metallic constituent is alloyed generally throughout the volume of material. A thickness of the bond pad can be reduced from an initial thickness T1 to a reduced thickness T2.

When soldering a package having an electrode on which Ni/Au or AgPd alloy is plated, to a printed circuit board having a Cu electrode or an electrode on which Cu is plated, a solid-phase diffusion layer is formed within a layered solder material for bonding different species of electrodes. The layered solder material is composed of a solder material of SnAgCu series or SnSb series and a solder material of SnAgCuNi series or SnPb series. The electrode on which Ni/Au or AgPd alloy is plated and the Cu electrode or the electrode on which Cu is plated are soldered with the solder material of SnAgCu series or SnSb series being attached to the Cu electrode and the solder material of SnAgCuNi series or SnCu series being attached to the electrode on which Ni/Au or AgPd alloy is plated. This restrains formation of intermetallic compounds and provides high bonding reliability.

A preform structure for soldering a semiconductor chip arrangement includes a carbon fiber composite sheet and a solder layer formed over the carbon fiber composite sheet.