A strain gage is disclosed comprising a backing strip and a strain grid having enlarged terminal lengths. Elongated tabs having integral, tapered connectors are also bonded to the backing strip. The connectors are bonded to the enlarged terminal lengths and are angled therefrom at approximately 45.degree. - 65.degree. from the direction of major strain when the gage is bonded to a test specimen. The tabs are also disposed in the same angular relationship. A cover sheet overlies the grid and tabs with apertures providing access to the latter.
A method of making a foil-type electrical resistance strain gage having a gage factor of at least 4. A PtW foil is adhesively bonded to a polyimide substrate with an FEP adhesive cured under heat and pressure. The foil is spin-coated with a positive photoresist, masked, and exposed to ultraviolet light. The exposed photoresist is then developed, permitting wet etching of the foil to form a gage pattern on the substrate, which is then preferably cured.
A precision resistor has a thin resistive foil cemented to a much thicker rigid substrate. The foil has formed therein a pattern defining the resistive path between terminal pads. Copper leads can be spot-welded directly to these pads without damage to the junction. To that end, apertures are provided through the terminal pads, through which cement softened by the spot-welding heat can locally expand and gas evolved under pressure can escape, all without adversely affecting the junction and without substantial lifting of the terminal pads from the substrate.
A resistance strain gauge in which a resistance layer is applied to a carrier and provided with terminal elements is particularly characterized in that a patterned, thin, non-self-bearing resistance layer is materially bonded to a synthetic layer, and that the resistance layer is overlapped by a patterned, solderable contact layer and is materially bonded to the contact layer.
A mechanical force to electrical signal transducer includes a flexible metal body operable as a beam in which a bending strain is to be measured as a measure of a mechanical force. At least a part of one surface of the metal body includes an electrical insulating material with a resistance element formed from a layer of a thick film resistor ink of the type used for thick film integrated circuits fused upon the electrical insulating material. A plurality of such transducers may be combined in a weighing scale, with the individual transducers electrically interconnected to provide for electrical summing of the transducer signals to provide a total weight measurement.
