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Absfrucf-Extended Man missions will require vehicles to siwive a large number of extended temperature cycles. To address this issue for electronics, previous strategies have placed electronics in a "warm electronics box" where thermal management is more easily maintained. However, that strategy limits number and location of electronics. An alternative strategy allows electronics to be remotely located on actuator and wheel arms with no heating, which has the advantage of distributed control. This strategy requires the electronics to survive the Martian extremes of-I20 to +2O"C for the duration of the mission. In addition, wheel motor controllers may be mounted directly on the motor casing extending the temperature range on the warm side to +XS°C (including somz margin). Since missions may last 18 months or more and with day-night cycles on Mars at about 26 hours this will mean exposure to approximately 500 cycles. Typical testing is performed to 3x the number of cycles giving the electronics a testing requirement of -120 to + 8 5 T for 1,500 cycles.A chip on board strategy was selected and a parallel approach of materials characterization and physics of failure with engineering experimentation is being used to address the issues of a large temperature swing with many cycles. A full factorial experiment, designed to highlight expected failure modes from the physics of failure analysis, is being conducted. The experiment is designed to evaluate different substrate materials, different die attach materials and different encapsulants or coatings. Combinations of these materials are being evaluated on a test vehicle with a range of die sizes in an effort to determine lifetime and to verify failure modes. Initial results will be presented.

Miniaturization of electronic packages will play a key role in future space avionics systems. Smaller avionics packages will reduce payloads while providing greater functionality for information processing and mission instrumentation. Current surface mount technology discrete passive devices not only take up significant space but also add weight. To that end, the use of embedded passive devices, such as capacitors, inductors and resistors will be instrumental in allowing electronics to be made smaller and lighter. Embedded passive devices fabricated on silicon or like substrates using thin film technology, promise great savings in circuit volume, as well as potentially improving electrical performance by decreasing parasitic losses. These devices exhibit a low physical profile and allow the circuit footprint to be reduced by stacking passive elements within a substrate. Thin film technologies used to deposit embedded passive devices are improving and costs associated with the process are decreasing. There are still many challenges with regard to this approach that must be overcome. In order to become a viable approach these devices need to work in conjunction with other active devices such as bumped die (flip chip) that share the same substrate area. This dictates that the embedded passive devices are resistant to the subsequent assembly processes associated with die attach (temperature, pressure). Bare die will need to be mounted directly on top of one or more layers of embedded passive devices. Currently there is not an abundant amount of information available on the reliability of these devices when subjected to the high temperatures of die attach or environmental thermal cycling for space environments. Device performance must be consistent over time and temperature with minimal parasitic loss. Pretested and assembled silicon substrates with layers of embedded capacitors made with two different dielectric materials, Ta2O5 (Tantalum Oxide) and benzocyclobutene (BCB), were subjected to the die attach process and tested for performance in an ambient environment. These assemblies were subjected to environmental thermal cycling from −55°C to 100°C. Preliminary results indicate embedded passive capacitors and resistors can fulfill the performance and reliability requirements of space flight on future missions. Testing results are encouraging for continued development of integrating embedded passive devices to replace conventional electronic packaging methods.