1. Bond with current pulses Bond without current pulses A closer look with 40500 frames/second video equipment Single frames have been digitized and a quantitative analysis has been performed.  Bonds were excited with limited number of pulses to measure the amplitude of the motion versus the number of pulses and the dumping ratio. 40 pulses in a row Free decay of the motion Conclusions Wire-bond failures induced by resonant vibrations in the CDF silicon detector Time line of the silicon integration in CDF for RunII Long after the end of commissioning a non negligible rate of permanent failures started to show up. Both failure modes are consistent with loosing the continuity on power lines on the non- accessible part of the detector. DVDD JUMPER connection  Loss of the Z side information  Wire bonds lying on a plane that is orthogonal to the magnetic field DOIM power connection  Loss of all information from the module  Wire bonds lying on a plane that contains the B Field vector but have a step up from a substrate to the other These are not the wire-bonds with the largest current in the system! Current surges (fusing the bond) were ruled out Aging mechanisms were ruled out JUMPER route control, power and data between r  and rZ sides of the double sided SVXII modules. DOIM are laser diodes packages that drive data from the tracking volume to the VME crates. Magnetic field. Lorentz Forces DOIM Bonds step up from the CPC to the substrate Similar motion as on the Jumper with 1/10 current Jumper Bonds Oscillating Current Most of the failures were tracked down to anomalous trigger conditions during data taking. Trigger TORTURE tests (to explore dead-time at high trigger rates) Synchronous!.  Fake triggers generated according to the fixed beam structure. Synchronous!. SVX3 chip can go in a HIGH occupancy (100%) mode if 5 th L1A is issued (buffer is only 4 deep) Synchronous!.  Long readout time drives CDF into issuing trigger with a fixed time interval between each other. Synchronous!. The wire-bonds that fail have relatively large  I during data taking. Up to 150 mA  I for the DVDD JUMPER bonds. No more than 40-50 mA  I for the DOIM bonds DOIM current DVDD JUMPER current AVOID trigger conditions that could resonate the bonds.  Administrative and Run-Control software. Understood and removed all possible spurious sources of the 5 th L1A  TS (Trigger Supervisor) firmware and Command Signal strength changes Current swing minimization  Reduce the power output of the bus drivers  Minimization of noise occupancy Trigger Inhibit on resonance (in place and being commissioned) CURRENT Minimization CDF operational response A perfect Wire-bond While resonated a crack grows at the heel The bond breaks on a time scale of minutes Wire-bonds break due to fatigue stress on their heel induced by resonant vibration. These resonant vibrations are a direct consequence of the oscillating Lorentz forces induced by the magnetic field on wire-bonds with non-DC current. Resonated bondPulled bond Resonant frequencies 2-3 natural resonant frequencies up to 50 kHz (range of interest for CDF) for realistically shaped bonds. Each resonant frequency f can be excited with pulses at f, f/2, f/4 etc The resonant system has a very high Q. The width of the resonance is about 1-200 Hz. Differently shaped bonds imply different resonant frequencies. Last fall the CDF experiment faced a crisis due to internal unrecoverable failures on the silicon detector. The source of the failures has been understood to be simple physics mechanisms that could have been taken into account during the design and construction of the hardware. Counter measures have been studied, developed and applied to the CDF experiment. Since these implementations are in place, no other failures have occurred. Gino Bolla, Purdue University for the CDF RUN2 Silicon Group9 th Pisa Meeting, La Biodola, Elba Italy, May 25-31 Small drops of encapsulant ( Sylgard 186 Silicone Elastomer from Dowcorning) limit the oscillation amplitude by more than a factor of 50 by covering just the first 50-100  m of the wire. We were not able to break these wire-bonds! Not real encapsulant