Tooling and assembly of US stavelet at Berkeley S. Díez Cornell, C. H. Haber, M. Defferrard, R. Witharm Sept 6th, 2012 Berkeley mechanical meeting, 5th-7th September 2012

 We developed simple tooling for manual assembly and testing of the US stavelet in a quick and easy way  Shield-less tape co-cured in between 0-90 CF layers  Double-sided: DC-DC and serial (serial side shown in the picture)  Al shielding still in one of the modules (honeycomb re-profiled in that region)  Al + polycarbonate inserts to place DC-DC converters (15 mm wide) Stavelet core 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting2

Mechanical tools for manual stavelet assembly  Stavelet frame  Core attached with 2 mm dowel pins Holes and slots drilled on core plastic inserts  Vertical 5 mm pins on stavelet frame  Module pickup tool + dowel pins  Based on module construction tools  Linear bearings on pickup tool  Modules picked up from module mounting jig by adding removable dowel pins 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting3

Stavelet attachment  Holes and slots drilled on stavelet polycarbonate inserts  2mm slip fit pins located with set screws on frame  Allows precision placement of core wrt frame 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting4

Pins for module placement  Stavelet is placed on the frame before locating the vertical pins on the frame  Metrology measurements determine the location of HV reference pads on the bus tape with respect to the stavelet frame  Pickup tool is referenced wrt those reference pads  Location of vertical pins is then determined  Allows re-positioning of the core anytime knowing the location of the reference pads 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting5

Module gluing 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting6 Silver epoxy : ● HV contacts to sensor backplane ● Two contacts (as opposed to previous stavelets) Fishing lines : ● 150 μm diameter ● Height control ● Allow to remove the SE4445 (but probably not the silver epoxy...) Three layers of low tack (blue tape) mask for SE4445 Very similar to the one used at RAL Additional Kapton tape layer to avoid electrical contact between HV backplane and CF shielding

Module placement  Module is vacuumed down on the ASICs and picked up from the module construction jig  The module is picked up with sensor-ASIC wire bonds (PUT gives 500 μm clearance)  Removable dowel pins keep the pickup tool in place  Linear bearings on the pickup tool fit the vertical pins on the frame  Fishing line controls glue thickness, it could also be done with washer shims on the pins 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting7

Glue trials 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting8 2 layers mask: ~160 μm of glue No glue spreading at all 3 layers mask: ~ 240 μm of glue (may need to change mask layout)

Other components  EoS and BCC boards attached with double sticky tape  DC-DC power:  Power bus tape (+1Wire lines) modification required due to higher current (~ 10 A) with respect to serial powering (~ 5A)  Converters go on top of the tape, there is a significant step (~ 550 μm) wrt the lateral inserts that prevents thermal contact between converters and Al inserts Step is even higher on the Al shielded module since the inserts were trimmed (~750 μm) AlN ceramic pieces glued down the inserts and the converters backplane with FH-5313 epolite to overcome the step and to get good thermal contact  EoS board doesn’t stand 10 A either >10A rated wires soldered directly on tape 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting9

US Stavelet so far  Started with DC-DC side, 3 out of 4 modules placed 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting10

Position of modules with respect to tape 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting11 ΔxΔx ΔyΔy Distance (mm) Module 0Module 1Module 2 (Al shield) Module 0Module 1 Module 2 (Al shield)  2 points per module on the power side  Δx = 1009 ± 146 μm  Δy = 565 ± 72 μm

 Target values and clearance: Δx = 500 μm, Δy = 0  Average glue thickness ~ 175 μm for all 3 modules Modules relative position 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting12 Module 1Module 0 Module 2 (Al shielding) 322 μ m 47 μ m 441 μ m 484 μ m 170 μ m 453 μ m

Stavelet electrical performances  3 DC-DC modules mounted so far  Module 0 was badly damaged during its removal from its individual test frame Last step in the process before placement on core, only one that didn’t involve test (now it does)  “Good” news is that now we can study module removal techniques… 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting13

I-V curves modules 1 and 2  IV curves during operation (cooled down, N2, LV power on)  FZ2 series II sensors (higher currents than FZ1 series)  Roughly an extra μA with respect to individual on both cases 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting14 Module 1Module 2 (Al shielding)

 Very fresh results (very first measurement of stavelet with 3 (2) modules)  ENC noise on module 1 is reduced by ~ e just by placing module 2  Excellent ENC noise results for module 1 ENC noise modules 1 and 2 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting15 646e 663e 633e 611e Module 1 Module 2 (Al shielding) 639e 663e 633e 601e

Hybrid to hybrid reference path  Low inductance connection required between GNDs of both hybrids of each module  Usual bus tape connects them through Al shielding  That is why the Cu squares are for in our tape  Problem: the (shortest path) pad for one of the hybrids is covered by the sensor Comes from the tape layout, not the module placement  Have to perform some surgery to achieve low inductance connection  Reduced noise of left hybrids by > 50e 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting16

NTCs and Sensirion humidity sensors  Data taken by sctdaq right after 3PointGain test  T Chiller = 9 C  Test box flooded with N 2 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting C23.4C21.5C21.4C23.8C22.0C 19.1C 3.4%RH 15.0C 4.5%RH

Lessons learned  The tools allow placement of the modules on the stavelet with a precision of ~150 μm  At a very first glance, and comparing with UK DC-DC stavelet, CF shielding works electrically as well as Al shielding  Al shielded module shows no particular advantage electrically wrt CF module  NTC measurements show uniform thermal behavior of all 3 modules  Pickup tool propagates quite some errors (location of module on pickup jig, hybrid gluing, cable deformation, location of bearing pins,…)  It would be better to have more control on the Z dimension, and also making the frame compatible with WB equipment  Still work in progress; will be interesting to see how serial side comes out 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting18

Future  Removal and replacement of defective module  Last DC-DC module and serial powering side to be populated in the following weeks  Modules already in hand (built at Santa Cruz)  Extensive electrical measurements foreseen in the near future  Second US stavelet (SP, single-sided) for BNL/Penn to be assembled with these tools  US-type core with CF side pipes Have to look for different attachment pins (“V-shaped” pins) 6th Sept 2012S. Díez Cornell, Berkeley mechanical meeting19