Ultra-miniature electrical contacts and method of manufacture

A method of forming ultra-miniature electrical contacts comprising the steps of:

• providing an insulated substrate on which conductive circuit traces can be deposited;
• defining by photolithography areas on the substrate;
• selectively depositing within each area at least two layers of metal upon each other to form a conductive body of a contact with one metal layer having a coefficient of thermal expansion higher than that of another layer and one end of the contact being fixed to the substrate;
• heating the body of the contact so that by differential expansion of metal layers the contact for most of its length beyond its fixed end is bent above the substrate, and at least a portion of the body near its other end is bent down toward the substrate;
• and
• over-plating with an outer metal layer the other metal layers to give substantial strength and resiliency to the contact, said outer layer consisting of a stiffening metal.

A method of forming an assembly of ultra-miniature electrical contacts mounted on a substrate and suitable for contacting contact areas of a device, the method comprising the steps of:

• providing an insulated substrate on which conductive circuit traces can be deposited;
• defining by photolithography areas on the substrate where contacts are to be located;
• depositing in each of the defined areas a conductive body of a contact having at least two layers of different metals selectively deposited upon each other with an end portion of one metal layer being connected to a portion of conductive traces on the substrate;
• heating each contact body so that by differential expansion of the metal layers the contact is permanently bent into a three-dimensional shape above the substrate;
• and
• depositing an outer metal layer over the plurality of metal layers so that the contacts have sufficient strength and resilience to effect stable low-resistance electrical contact to contact areas of a device said outer layer consisting of a stiffening metal.

A method of forming electrical contacts comprising the steps of:

• providing an insulated substrate on which conductive circuit traces can be deposited;
• defining by photolithography regions on the substrate;
• selectively depositing within selected areas of the regions at least two layers of metal upon each other to form a conductive body of a contact with one metal layer having a coefficient of thermal expansion higher than that of another layer and with one end of the contact being fixed to the substrate;
• heating the body of the contact so that by differential expansion of metal layers the contact for most of its length beyond its fixed end is permanently bent into a coil above the substrate;
• and
• covering the at least two layers of metal with a third metal layer to add additional strength and resiliency to the contact, said metal layer consisting of a stiffening metal.