1. Berkeley status
Aug 10th, 2012

2. 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
12/17/2017

3. Stavelet core
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
12/17/2017

4. Mounting tools 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.
12/17/2017

5. Module placement
Linear bearings allow the pick-up tool to move vertically but not horizontally
Module position controlled by the dowel pins.
12/17/2017

6. Gluing Silver epoxy : Electrically conductive
HV contacts to sensor backplane
Two contacts (as opposed to previous stavelets)
Three layers of low tack (blue tape) mask for SE4445 
Very similar to the one used at RAL
Fishing lines :
125 μm diameter
Height control
Allow to remove the SE4445 (but probably not the silver epoxy...)
12/17/2017

7. Glue spreading 3 layers mask: 240 μm of glue
Glue spreads, but not perfect
(may need to change mask layout)
2 layers mask: 160 μm of glue
no glue spreading
12/17/2017

8. First 2 modules glued
12/17/2017 8

9. US stavelet so far
Pins + set screws for precision positioning of the core
Carbon fiber shielding connection
LV power supply soldered on DC-DC tape
STAR connection to DC-DC converters
12/17/2017

10. Module 0 Horrible looking scratch on guard ring
Sensor current goes > 100 uA at -5 V, also when cooled down
Ohmic behavior
12/17/2017

11. 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)
12/17/2017

12. 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!)
12/17/2017

13. First tests First tests from yesterday evening:
Module 0 (broken sensor, not biased)
Hybrid 55
Hybrid 56
~ 1100 e
~ 1100 e
12/17/2017

14. 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)
Hybrid 57
Hybrid 58
~ 710 e
~ 650 e