Test of HV Prototype Boards for LHCb Outer Tracker NIKHEF, Amsterdam The Netherlands 2003-10-16.
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Transcript of Test of HV Prototype Boards for LHCb Outer Tracker NIKHEF, Amsterdam The Netherlands 2003-10-16.
HV Boards
Johanson Capacitors PCB Embedded
Working HV = 1,600V
Mass Production: 1,950
Test items:
Leakage Current
Capacitance
Micro-cracks inside Caps
x 32
Experimental Setup (cont.)
HV = 2kV, Thermal Cycling = 20oC ~73oC,
Time = 24days, 15 boards are tested
Temperature Cycling • Temperature Cycle: 20oC 45 min.
20oC 73oC 15 min.
73oC 45 min.
73oC 20oC 15 min.
• Relative Humidity, not controlled, but kept low when temperature goes down
Due to unknown error of the temperature control system
Leakage Currents
Leakage currents of 15 boards are logged,
as well as the temperature and relative humidity
One Thermal Cycle
Left: with gnd net on HV board connected
Right: only 32 output pins of capacitors connected
Contribution from HV to gnd net on HV board:
~1nA@T=20oC and ~10nA@T=73oC
Correlation with Temperature and RH
Spread at T=73oC (T=20oC) is caused by time needed to warm up (cool down) the capacitors inside PCB
Not sensitive to RH anymore
Spikes
It is highly suspected that:
T goes down to <0oC due to unknown error;
ice formed on the board surface;
T goes up to 0oC, ice turns to be water to make board surface conductive
current spike occurs
Leakage current at T=20oC
Ileak of each board ↓
< 2nA, including the component from HV to gnd net on HV boards
Capacitance Measurement
• 480 Capacitors 479: ~30pF less than before
1: 187pF, 2/3 of other capacitors
• A crack found under microscope