TRIO-CINEMA 1 UCB, 2/08/2010 End of Summer Review Kevin Jenkins Mechanical Engineering Space Sciences Laboratory University of California, Berkeley

TRIO-CINEMA 2 UCB, 2/08/2010 Agenda Solar Arrays PCB Redesign Assembly Testing Vibration Testing Test setup STEIN Attenuator Safety Circuit Torque Coils Prototype assembly and testing

TRIO-CINEMA 3 UCB, 2/08/2010 Solar Array Previous PCB design Red traces here are surface traces on board Stripe design allows for large enough contact area Stripes require epoxy to be close to edges of cells PCB Redesign

TRIO-CINEMA 4 UCB, 2/08/2010 Solar Array PCB Redesign Conferred with Yashraj Khaitan in India for advice Triangular red traces on surface of board Epoxy can stay away from edges of cells

TRIO-CINEMA 5 UCB, 2/08/2010 Solar Array PCB Redesign One configuration with wider tabs for greater strength and versatility of screw placement Other configuration with smaller tabs that do not block sun sensor FOV where placed

TRIO-CINEMA 6 UCB, 2/08/2010 Solar Array Assembly Cells within pairs are matched by current to within 5%, usually better Pairs within a panel are matched by voltage as closely as possible Cells and pairs are numbered for reference

TRIO-CINEMA 7 UCB, 2/08/2010 Solar Array Assembly Start with board, tabs machined Roughen board surface with scotchbrite and then clean with alcohol Apply silver epoxy mixture with a razor blade, cleaning any mistake spots with a swab

TRIO-CINEMA 8 UCB, 2/08/2010 Solar Array Assembly Cells are placed with a vacuum chuck onto the panel Cell placement may be adjusted with the vacuum chuck once they are placed on the board

TRIO-CINEMA 9 UCB, 2/08/2010 Solar Array Assembly Boards are inspected under a microscope for proper cell placement prior to cure Contact pads must be uncovered, cells may not be touching

TRIO-CINEMA 10 UCB, 2/08/2010 Solar Array Assembly Boards are encapsulated with CV material from nusil Optically clear Protects from radiation and particulates Structural adhesive Controlled volatility

TRIO-CINEMA 11 UCB, 2/08/2010 Solar Array Assembly CV comes in two components Must be mixed and then deaerated before application

TRIO-CINEMA 12 UCB, 2/08/2010 Solar Array Assembly Encapsulant is applied to board with camel-hair brush Panel must be deaerated again after application

TRIO-CINEMA 13 UCB, 2/08/2010 Solar Array When air pressure is reapplied to board after dearation, encapsulant fills gaps under cell This helps bond the cells to the panel Panels must be electrically tested before and after encapsulant application Assembly

TRIO-CINEMA 14 UCB, 2/08/2010 Solar Array Testing Panels are first tested for electrical performance Testing may be focused on individual cells or entire panels depending on wiring Testing was conducted in 2 settings: Controlled lab light Sunlight

TRIO-CINEMA 15 UCB, 2/08/2010 Solar Array Testing Panels electrically tested at several stages of assembly Want to know what effect different components have on power Main tests are after diode placement and after encapsulant

TRIO-CINEMA 16 UCB, 2/08/2010 Solar Array Testing Panels are sent through thermal cycling to determine durability One Thermal cycle is 45 minutes at 100°C, then 20 minutes at -20°C, plus warm- up and cool-down times A test is 3 cycles Electrical testing is repeated after thermal cycling

TRIO-CINEMA 17 UCB, 2/08/2010 Solar Array Testing Testing was necessary to determine whether to use diodes Compared power loss with diodes to loss from back- current in cells with shadow Shadowed ½, 1, 2, and 3 pairs to determine current losses

TRIO-CINEMA 18 UCB, 2/08/2010 Solar Array Testing Results for Panel #5 Shadow Testing CoveredTestPair Current (mA)Panel (mA) Cell 7aNo Shadow Shadow0242 Pair 7No Shadow Shadow Pairs 7, 8No Shadow Shadow Pairs 5, 7, 8No Shadow Shadow

TRIO-CINEMA 19 UCB, 2/08/2010 Solar Array Tested panels for induced magnetic field Tested in periodic pattern to separate panel signal from earth noise Magnetic gradient determined on [0,5] inches through panel normal axis Testing also conducted along panel horizontal axis at 2 inches from panel plane Testing

TRIO-CINEMA 20 UCB, 2/08/2010 Testing Solar Array

TRIO-CINEMA 21 UCB, 2/08/2010 Vibration Testing Testing Setup Test assembly designed to hold solar panels, STEIN, and mag. boom All brackets needed to have resonance above 1000Hz to be used in test

TRIO-CINEMA 22 UCB, 2/08/2010 STEIN Attenuator Safety Circuit Nanomuscles on attenuator have been worn down and overheated due to accidental misuse A 556 safety timer was designed to allow for proper cooldown between firings 150ms on, 60s disabled

TRIO-CINEMA 23 UCB, 2/08/2010 Torque coils Prototype assembly and testing Full-size prototype bult to test field and practicality of construction Prototype’s generated field gradient determined through testing Proposed number of turns barely fit in setup, possibly due to winding technique

TRIO-CINEMA 24 UCB, 2/08/2010 Thank You