Prequalification document Amsterdam, 3 April 2003 Fred Hartjes, (Paul de Jong), Sandra Muijs, Joop Rövekamp
Overview • This document contains the results of all QA tests performed during the assembly of the prequalification modules • Description of the assembly and the QA procedure followed at NIKHEF can be found in separate documents • In total 3 modules have been assembled and tested: 1 mechanical dummy and 2 electrical dummies • The first half of this document contains the reception test that are used for component selection • The second half describes the test on the completed modules
Component reception tests • Sensors: • IV curves • (Quick check under microscope to look for obvious defects) • Hybrids: • Visual inspection under microscope • Metrology (z-plane) • Electrical test: confirmation sequence • Spine: • Thickness verification
Sensor reception tests: IV curves • For both electrical modules sensors from batch 5005 were used: • module K5-511: wafers 5 and 6 • module K5-512: wafers 1 and 13 • Wafer 5005-13 was selected even though it has an early breakdown, • but this module is an electrical dummy so we did not want to use the • best components we had in stock. • Also Wafer 5005-1 has a breakdown, but only at very high voltages.
Wafers selected for module K5-511 Wafers 5005-5 and 5005-6. IV-curves measured at NIKHEF, compared with those measured by the manufacturer CiS (from the database info). Results agree very well.
Wafers selected for module K5-512 Wafers 5005-1 and 5005-13 IV-curves measured at NIKHEF, compared with those measured by the manufacturer CiS (from the database info). Wafer #1 has a breakdown above 400V, which is obviously not observed by the manufacturer Wafer #13 has a clear early breakdown, but it remains inside the manufacturer’s specs (< 20 A at 350V) Wafers are selected for dummy modules only.
Metrology results • While assembling K5-511 we had a problem with the tooling while using for the first time a spine with a reinforced tongue. As a result the spine and far-end washer have been moved across about 200 µm in X while the main washer is about 150 µm too high in Z. However the position of the relevant items (detectors, hybrid, fan-ins) has not been affected. The tooling has been modified to avoid this error in future.
Hybrid reception tests: visual inspection K5-511 • K5-511 VDC surface looks scratched. Big pads in the middle are seriously damaged (probably not problematic). Some of the lines might be affected. weblink to picture of VDC • DORIC has low bonds (weblink to picture of DORIC). • ABCD S4 damaged edge (from dicing) on hybrid side, under bonds. • ABCD S10 drop of spit (?) on input pad. • One ABCD chip was not correctly glued. As a result, the bonds touch the edge of the chip (weblink to picture). • None of these little defects caused problems in the electrical tests later.
Hybrid reception tests: visual inspection K5-512 • VDC: some damage (see picture of the VDC) • DORIC: surface looks scratched (see picture of the DORIC) • ABCD S1 has a scratch • None of the defects seems to cause problems in the electrical tests
Hybrid reception tests: z metrology K5-511 • Hybrid is V-shaped around the cooling block with an amplitude of 150 – 200 µm, possibly due to the assymetry between the upper and the lower kapton flex. This appears to be a typical phemenon for most hybrids • In contrast to the hybrids used for the NIKHEF miniproduction in 2002, the HV tongues do no longer curl up
Hybrid reception tests: z metrology K5-512 • Hybrid is again V-shaped with an amplitude of 150 – 200 µm
Module QA tests • Metrology of the module after bonding • Thermal cycling and again metrology • Full electrical characterisation • IV curve of the module after bonding
Module K5-511 z metrology • Z metrology of the module before thermal cycling.
Module K5-511 xy metrology • before thermal cycling
Module K5-511 z metrology after thermal cycling • The module has been cycled 10 times from –30 to +50 degrees and back, in ~24 hrs • The z metrology is much worse after thermal cycling.
IV curves module 511 IV curves at different stages during the assembly: In blue, the sum of the IV curves of the individual wafers (reception tests) In orange, the corresponding measurements made by CiS In green, the sum of the front and back wafer after they have been glued to the spine In red, the IV curve of the module, after bonding The breakdown behaviour of the unbonded glued wafers is observed before in earlier modules made at NIKHEF. It appears to be typical behaviour for CiS wafers: as long as they are unbonded, the behaviour is rather unpredictable.
IV curves module K5-512 IV curves at different stages during the assembly: In blue, the sum of the IV curves of the individual wafers (reception tests) In orange, the corresponding measurements made by CiS In green, the sum of the front and back wafer after they have been glued to the spine In red, the IV curve of the module, after bonding The breakdown did not disappear after bonding, so these wafers were indeed not good enough to build modules (NB they were selected for dummy modules only).
Study of bond heights in K5-511 • Bond heights all tuned not to exceed 0.5 mm above chip and fan-in surface • Lower bonds all exceed 0.5 mm above detector edge