Rockwell International Corporation

Boeing North American, Inc.

Rolin K Asatourian

Winfred L Morris

Michael Royston James

Donald E Cooper

A focal plane array (FPA) including a layered composite structure having several layers of materials with differing thermal expansion coefficients (TECs) and thicknesses to stabilize and maintain FPA performance during thermal cycling and excursions. An optical substrate is coupled to a multiplexer through a network of indium bumps. The typical TEC mismatch of the layered materials is offset by particularly selecting the types of materials used and the thicknesses of the individual layers of the FPA. Consequently, undesirable deflections and distortion of the multiplexer and the indium bumps are minimized, thereby substantially improving FPA reliability.

Imbalanced layered composite focal plane array structure

A hybrid focal plane array (FPA) structure including a soft, localized, and thick epoxy for supporting the FPA on a cooling device. The hybrid FPA arrangement includes a crystalline optical substrate with a layer of an optically sensitive material disposed on one surface of the substrate. The optically sensitive side of the substrate layer is coupled to a MUX chip via an interconnection scheme. The layered configuration of the detector, the optically-sensitive material, interconnection network, and the MUX is mounted to a platform or dewar cold plate with a pliable, thick epoxy which is locally deposited onto the platform to effectively form a raised mounting cushion which supports the MUX and reduces deleterious effects resulting form a close coupling of the FPA to the mounting platform.

Stabilized hybrid focal plane array structure

A focal plane array (FPA) mounted in an imbalanced configuration including several layers of materials with differing thermal expansion coefficients (TECs), moduli of elasticity, and thicknesses to maintain surface planarity and improve the reliability of the FPA during thermal cycling and excursions. An optical substrate is coupled to a multiplexer through an array of indium bumps. The typical TEC mismatch between the optical substrate and the multiplexer is eliminated by forcing the multiplexer to exhibit an effective TEC equal to that of the optical substrate by particularly selecting the types of materials used and the thicknesses of the individual layers of the composite structure. Consequently, undesirable deflections and distortion of the multiplexer and the indium bumps are minimized, thereby substantially improving FPA reliability.

Imbalanced composite focal plane array

A hybrid focal plane array (FPA) structure including a Balanced Composite Structure (BCS) in which several layers of materials having differing thermal expansion coefficients stabilize the FPA during cryogenic cooling. An optical substrate with a layer of an optically sensitive material detects impinging radiation. The optically sensitive material is coupled to a multiplexer (MUX) substrate via interconnection bumps. The MUX is bonded to a layer of a material having a high TEC. A rigid core layer is sandwiched between the MUX and a balancing layer formed of a material having similar mechanical and geometrical characteristics to the MUX substrate. The three-layer BCS consisting of the MUX, the rigid core layer and the balancing layer is designed to have an effective TEC matching that of the optical substrate. The bumps and the optically sensitive material are thus protected from undesirable stresses generated during thermal excursions, thereby resulting in substantially improved FPA reliability.

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Fullerton, CA, United States of America

Rolin K Asatourian