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Green Tape™ Provides High Reliabilty for Satellite Control Circuits

Space Systems/Loral Inc. of Palo Alto, CA, a leader in the aerospace industry, produces direct-broadcast, relay communications and weather satellites. The company's substrate fabrication division has turned to DuPont's Green Tape™ technology to meet the demand for high-reliabilty hybrids.

Challenge: Reducing Control Circuit Crowding

One type of circuit currently produced by Loral Inc. is the Control Circuit, used to regulate power to microwave modules. Initially, Loral's Control Circuits were designed and manufactured using conventional thick film processes; however, circuit density required 5-mil lines and spaces. The fine lines created high IR loss, and circuit design was complex and crowded. The crowding created difficulty during component attach in hybrid assembly.

Solution: Multilayer Circuits Using Green Tapeā„¢

The solution was to use DuPont's Green Tape™ technology to create a multilayer circuit. The Control Circuit was expanded in the z axis by the addition of several layers. This expansion allowed Loral's manufacturing team to use 10-mil lines and spaces, resulting in lower line loss and resistance. And by simplifying the top layer pattern, Green Tape™ enabled the hybrid assemblers to focus on the emergence patterns.

Green Tape™ also allows the Control Circuit's RF stripline and microstrip features - as well as bias control circuitry - to be integrated into a single LTCC package. Integration into a single package has several advantages: high weight savings (due to dense circuit design), high reliability (due to fewer interconnects), quick prototype turnaround, and the ability to implement immediate design changes, as well as flexible design options.

The control circuit shown has eight layers, nine conductive layers (including ground plane), 10-mil lines and spaces, and an average of 150 vias per layer. The circuit was manufactured as part of a 12-up array using DuPont's 951 Tape, 5734 for the conductors, and 5718 for the via fill.

Satellite hardware must perform reliably in a rigorous environment for an extended period of time, and over a wide temperature range. The Green TapeTM Control Circuit has passed rigorous aerospace standards, including temperature cycling of -55 to 125° F.

For more information, call DuPont at 1-800-284-3382, press 3.