Thermal Characterization of a Twist Capsule Flex-PCB for Solar Array Drive Assembly

Details

Supervisors

Herman, Benoît ; Louis Dechambre

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électromécanicien, à finalité spécialisée: mécatronique

Abstract

enThis thesis investigates the thermal behaviour and redesign of the Flex-PCB power-transfer architecture used in a twist-capsule Solar Array Drive Assembly (SADA) developed by Aerospacelab. A lumped-parameter thermal model was developed and compared with Thermal Vacuum (TVAC) measurements. In the isolated Flex-PCB configuration, the model reproduced the measured temperature rise with a maximum relative error of 7.6% and predicted that approximately 80% of the generated Joule heat was rejected by radiation. Testing in the complete twist-capsule identified the connector as a major thermal limitation of the original design. Based on these results, a redesigned architecture was proposed. A 16-position right-angle connector was selected, and an experimentally corrected IPC-2221 sizing method led to a retained trace width of 2.45 mm. A geometric model further indicated that reducing the rotor diameter from 55 mm to 50 mm allows the required angular range to be reached with an estimated Flex-PCB length of 556 mm. The fatigue analysis predicts a copper lifetime well above the 120,000-cycle qualification objective. The redesigned assembly has not yet been validated with all five Flex-PCBs powered simultaneously. A dedicated five-Flex TVAC campaign therefore remains the main verification step before qualification.