Ultra-miniature electrical contacts and method of manufacture

An ultra-miniature electrical contact comprising:

• an elongated conductive body formed of at least two layers of different metals selectively deposited upon each other;
• a portion of the contact being adapted to be fixed to a substrate;
• a remaining portion of the contact being permanently bent into a coil and lying above the substrate as a result of differential expansion of metal layers;
• and
• an outer stiffening metal layer being deposited over the plurality of metal layers, the stiffening metal layer being of metal electrodeposited from a palladium plating solution such that the contact has sufficient strength and resilience to effect stable low-resistance connection to a member to be contacted.

An assembly of ultra-miniature electrical contacts mounted on a substrate and suitable for electrical contact to contact areas of a device such as an integrated circuit, at least one of the ultra-miniature electrical contacts comprising:

• an elongated conductive body having two ends and formed of at least two layers of metals selectively deposited upon each other;
• one metal layer having a coefficient of thermal expansion higher than that of other layers;
• one end of the body of the contact being adapted to be affixed to the substrate, the body of the contact by differential expansion of metal layers being bent above the one fixed end of the contact and the substrate;
• at least a portion of the body of the contact near its other end being bent down toward the substrate as a result of differential expansion of metal layers;
• and
• an outer stiffening metal layer being electrodeposited on the other layers to give substantial strength and resiliency to the contact.

An assembly of ultra-miniature electrical contacts mounted on a substrate and suitable for making electrical contact to surface pads of a device such as an integrated circuit (IC), said assembly comprising:

• a substrate;
• an elongated conductive body formed on the substrate as at least two layers of different metals selectively deposited upon each other, one layer being a thin ribbon-like strip continuous along the body, another layer being selectively deposited on the one layer for a short distance along the one layer;
• a portion of the contact being affixed to the substrate;
• a remaining portion of the contact being permanently bent into a three-dimensional shape above the substrate as a result of differential expansion of metal layers;
• and
• an outer stiffening metal layer being deposited over the plurality of metal layers such that the contact has sufficient strength and resilience to effect stable low-resistance electrical contact to a surface pad of an IC device.