Ph.D. Thesis Colloquium


                                         Ph.D. Thesis Colloquium 

NAME OF THE CANDIDATE   :  Ms. Manju S Nair 

DEGREE                                   :  Ph.D. (ERP) 

TITLE OF THE THESIS            :  Self-healing in space electronics circuits.

SUPERVISORS                        :   Prof. Sanjiv Sambandan & Dr. Sreelal (ISRO)

DATE & TIME                           :   Monday, 17th January 2022 at 02:00 PM. 

VENUE                                      :  Online (Microsoft team) Link



     Self-healing in space electronics carries the possibility of creating a paradigm shift in engineering space systems with lesser complexity and mass. Space electronics plays a crucial role in the success of a mission as it acts as the brain, linking diverse systems and generates synergy. The possibility for the faults to develop are more in spacecraft due to long-duration exposure to operating environments of temperature, vacuum, radiation and cyclic operations. Space electronic packages consist of printed circuit boards, and they, in turn, have numerous crisscrossing copper tracks carrying crucial signals. Open interconnect faults that may occur in these tracks during the package operation plays a crucial role in the operational reliability of the mission. These damages can lead to degraded performance, progressive failures detrimental to the payload or the satellite itself.

     In space missions during the fault scenarios, troubleshooting and repair are almost impossible from the ground unless there is an automatic active healing system in the spacecraft itself. The thesis contains an exhaustive literature review regarding the studies conducted globally in this area. However, all those self-healing processes mandated alterations in the process chain of PCB fabrication, as in the case of stretchable conductive tracks and microencapsulated capsules. The primary goal of this thesis was to find an active space-qualified self-healing technique that does not pose a hindrance to the production chain of space electronics PCBs. As part of research studies in this thesis, eFASH was finalised, and extensive studies were carried out to assess the efficacy of this system in simulated conditions of the space environment. The fresh possibilities of mediums for eFASH, space compatibility studies on mediums and encapsulants, successful demonstration of eFASH in these innovative mediums, and eFASH demonstration in space simulated conditions are novelty factors of this thesis. The development of a self-diagnosed, self-correcting system for space electronics that periodically tests the track integrity and self-heals, restoring the functionality, is another contribution presented in this thesis.

     The studies in the first part of this thesis focus on eFASH studies with new suitable mediums. This part also covers the characterisation studies of eFASH carried out by perturbing various influential parameters, which provide insight into the process. The mediums that supported eFASH were only subjected to further space compatibility studies covered in the later sections of the thesis.

   The subsequent part of this thesis presents the studies under ASTM E595, and ASTM D2196-15NB standards on characterising various parameters like outgassing and viscosity of the eFASH compatible different mediums qualified in the first part. This part also focuses on research work carried on space-compatible encapsulants needed for the eFASH dispersion packaging essential in eFASH enabled PCBs.The research on the effectiveness of the eFASH method and its sustainability under space vacuum conditions when subjected to thermal extremes is also presented here.

     The third part of the thesis deals with the efficacy studies of the eFASH selfhealing technique in a vibratory environment. This section elaborates on the characterisation studies conducted in various vibration modalities like sine and random profiles, various frequencies, modes and magnitudes.

    The final part deals with the concept, design and development of an autonomous embedded boosted eFASH healing system and its features. The periodic prognostic testing approach adopted in this thesis is also elucidated here.

The thesis contains several novel findings as answers to these questions :

• The suitable self-healing technique for space electronics inflicting minimum/no repercussions on the existing manufacturing line of the space-qualified PCBs.

• The demonstration eFASH with novel mediums other than commercial silicone oil.

• Identification of new space compatible mediums for eFASH and encapsulant for dispersion packaging.

• The efficacy of eFASH in space simulated conditions of thermovacuum and vibration, demonstrating its feasibility.

• An expandable pluggable prognostic system for autonomous recovery in the case of single and multiple co-occurring track open faults.

    The research presented in this thesis is pertinent in the context of the advances in micro and nanosatellite technology constrained with severe mass and size restrictions. This eFASH self-healing in space electronic packages can ensure additional reliability to the subsystems boosting their capability of surviving launch, separation, docking, landing manoeuvres and meeting indented objectives during transit, in orbit and landing. This will, in turn, extend the usable life span of the spacecraft too.

     This thesis contains many original studies and novel conclusions that can transmute space electronics with eFASH enabled PCBs. The research work presented in this thesis can lay the foundation for further investigations, which will be beneficial for self-healed space electronics. This thesis acts as an enabler for future space technology in the facet of the emerging space economy.


                                                         ALL ARE WELCOME 


Date(s) - 17/01/2022
2:00 pm - 3:30 pm

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