Active Sensors Unit assembly process for the ATLAS High Granularity Timing Device D. Lacour for LPNHE Paris group 1. Introduction: Calice Si-W calorimeter concept 2. Gluing and positioning automated device description 3. Gluing tests on different geometries 4. Summary - next steps Didier Lacour LPNHE Santa Cruz, March 2016 1
Calice Si-W calorimeter concept Active sensor unit: Si sensors PCB Electronics Sensors are glued with a 20um precision and reproducible process. Glue is dispended in order to form 200 um thick dots. 2
Calice detector layers assembly and tests Assembly done with gluing and positioning robots: automated system developed in the framework of the Calice R&D program Electrical test to control the sensors before gluing, to check the short cuts immediately after gluing to measure the I(V) curves Metrology using a coordinate measuring machine (tri-dim machine): squaring, parallel edges, size, thickness flatness 3
Gluing and positioning automated process Cartesian robot (XYZ monitoring) : arm supporting suction cup and camera. Control cabinet of the positioning robot Plate for one wafer Hinged plate for 4 sensors PCB plate Gluing robot Glue dispenser Plate for GelPak box + wafer Syringes for glue deposition 4
Assembly steps Position 4 sensors, one by one (cartesian robot): each sensor is taken from the supporting plate and driven to the hinged plate to be placed at the right position. Done four times, very precisely thanks to a map which has been defined before. The position is also checked with the camera. The sensors are maintained with a vacuum pressure system (-1 bar). Deposit glue onto the PCB (dispenser robot): 2 syringes are used to dispense glue. The PCB is also maintained with a vacuum pressure system (-1 bar). The plate with 4 sensors is tuned onto the PCB. The two plates are maintained together during the glue polymerisation. Heating resistances are used for the polymerisation (40 C) 5
Gluing tests on different geometries Calice geometry 4 wafers / PCB Sensor parameters Dimension up to 90 x 90 mm Pads 5 x 5 mm Thickness 330 µm 256 X 4 = 1024 glue dots Glue dots After gluing (glass plate) 6
Gluing tests on different geometries First test with dummy boards with copper pads using Calice pattern Matrix pitch : 5 mm Pad dimension : 3 x 3 mm, limit for the process Decrease the capacitance value 7
Gluing test on 3 X 3 and 2 X 2 prototype geometry 4 geometries : 3 X 3 matrix Copper pads: 1.7*1.7 mm² Inter-pad gap: 0.3 mm 2 X 2 matrix Copper pads: 1.7*1.7 mm² Inter-pad gap: 0.3 mm 2 X 2 matrix Copper pads: 2.7*2.7 mm² Inter-pad gap: 0.3 mm 3 X 3 matrix Copper pads: 2.7*2.7 mm² Inter-pad gap: 0.3 mm To simulate 3*3 pads pin diode 2*2 pads LGAD 8
Gluing test on 3 X 3 and 2 X 2 prototype geometry The dummy PCB is extremely flat PCB, and is not equipped ( no components) Glass plate : 9 cm X 9cm 300 µm thick 9
Test on 3 X 3 mm prototype geometry: 3 X 3 and 2 X 2 pads Dispenser pressure: 2 3 bar Glue thickness: 200 µm Test on 2 X 2 mm prototype geometry Dispenser pressure: 0.5 bar Need to reduce the amount of glue to prevent short-circuits Minimum glue thickness for mechanical support = 150 um Then, the amount of glue is no longer sufficient to ensure electrical contact 10
Summary - next steps Pitch mm Pads surface mm² inter-pad gap mm Dispenser pressure bar Glue thickness µm mechanical strength / electrical contact / no short-circuit 5.5 5 X 5 0.5 3-4 200 OK 3 2.7 X 2.7 0.3 2 3 200 OK 2 1.7 X 1.7 0.3 0.5 150 NO For the time being, 3 X 3 mm pads geometry is compatible with the gluing process The method does not allow an electrical contact for 2 X 2 mm pads geometry Next steps: Gluing test with round copper pads smaller than the glue dots (as small as possible) to decrease the PCB capacitance Use thinner glass plates (100-150 µm) to check handling method Study the radiation hardness of the glue at JSI (AIDA2020) Fluence levels: 5.10 15 n/cm², 2.10 16 n/cm², 5.10 16 n/cm² - Samples : electrical et mechanical behavior of the glue after irradiation. Study the thermo-mechanical effects : thermal aging at -20 C of one ASU 11