Berkeley status

Aug 10th, 2012

US stavelet: status

Already glued the first 2 modules of the DC-DC side of the US stavelet First electrical tests just performed last night

M. Defferrard contributed to most of this work during the last 3 months, some of the next slides are his

04/20/23 2

Stavelet core

04/20/23 3

Aluminum shielded module for comparison

Initial idea was to start with shielded module, but that would have many complications during the assembly (glue application, placing of converters,…)Decided to go from the EoS side to the other

Mounting tools

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Pickup tool

Stavelet frame

● Pick the Modules by vacuum on top of the ABCNs, leaving enough clearance for the wirebonds.● Place them precisely on the Core : ~ 500 μm between the silicon sensors, pads for wire bonding.

Module placement

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Linear bearings allow the pick-up tool to move vertically but not horizontally

Module position controlled by the dowel pins.

Gluing

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Silver epoxy :● Electrically conductive● HV contacts to sensor backplane● Two contacts (as opposed to previous stavelets)

Fishing lines :● 125 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

Glue spreading

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2 layers mask: 160 μm of glue

no glue spreading

3 layers mask: 240 μm of glue

Glue spreads, but not perfect

(may need to change mask layout)

First 2 modules glued

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US stavelet so far

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LV power supply soldered on DC-DC tape

STAR connection to DC-DC converters

Carbon fiber shielding connection Pins + set screws for precision positioning of the core

Module 0

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Horrible looking scratch on guard ring

Sensor current goes > 100 uA at -5 V, also when cooled down

Ohmic behavior

How and when? Sensor was tested prior to be used for a module, and as an individual module Picture on slide 8 shows the scratch already (if you look carefully)

That was taken right after the gluing on the core, meaning that this was not caused during the DC-DC converters placement, soldering of “star' connection, LV cable soldering, or final bonding stage

Hard to believe the pickup process did something like that to the sensor The scratch looks like if it was made with metal tweezers

My conclusion is that I did that to the sensor when removing the glue on the corners of the hybrid that attached the module to the individual test frame Only previous step that did not involve subsequent testing

The module will probably be very difficult to remove due to the silver epoxy for the HV contacts We decided to leave it there and glue the second module (we can still disable it with the 1-

wire control)

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Other HV: SCT HV supplies on a VME rack

HV controller on Labview developed by M. Defferrard

LV: Sorensen XPF60-20D (60 V, 20 A) dual output power supply (can power both the serial and the DC-DC side at the same time) Looks identical to CPX400DP from TTi So far controlled manually

Cooling and shielding box around the stavelet frame HSIO borrowed from UK batch (thanks) Latest software and firmware versions installed and working (thanks Peter, Matt,

Bruce!) USB-RJ11 1 wire interface and interface board Followed bonding schemes for DC-DC stavelet that Peter circulated last week (thanks

Peter!)

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First tests First tests from yesterday evening: Module 0 (broken sensor, not biased)

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Hybrid 55 Hybrid 56

~ 1100 e ~ 1100 e

First tests First tests from yesterday evening: Module 1:

Roughly 100e more than individual module (DC-DC powered) Very fresh results! (this is just the very first test of the stavelet from last night)

14

Hybrid 57 Hybrid 58

~ 710 e ~ 650 e