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HV boards 1.FIRST ASDBLR HV PROTO BOARD: leakage currents on 100nA CH, humidity at cern. 2. TRIAL 1 Encapsulate caps in Printed Circuit Board 20-80 C schock, Ileak 1nA, (later increase) 3 broken caps Sparking under cap’s Test cycles 10-80C for 2 weeks, 3. TRIAL 2 improved casting, pick and place paste, no cleaning slurry Still broken capacitors (not HV but mechanical) Curved boards 4. TRIAL 3 Still broken caps Now thermal shocks -40 to +120 C Most probably Rework solder problem 5. TRIAL 4 Now better mounting on flat bad, ‘no rework’ , capacitor monitorring Status HV boards
