A Low Mass On-chip Readout Scheme for Double-sided Silicon Strip Detectors

A Low Mass On-chip Readout Scheme for Double-sided Silicon

Strip Detectors

13th February 2013

C. Irmler, T. Bergauer, A. Frankenberger, M. Friedl, I. Gfall, A. Ishikawa, C. Joo, D.H. Kah, R. Kameswara, K.H. Kang,

E. Kato, G. Mohanty, K. Negishi, Y. Onuki, N. Shimizu, T. Tsuboyama, S. Schmid, M. Valentan

VCI 2013, 13th Vienna Conference on Instrumentation

VCI 2013, C. Irmler (HEPHY Vienna)

Outline

• Introduction• Assembly• Cooling• Summary

213th February 2013


Motivation

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~1 km in diameter

Super KEKB Belle II

Linac

About 60km northeast of Tokyo

• Super KEKB– Electron-positron collider– 7 GeV e- on 4 GeV e+

– Center of mass energy: Y(4S) (10.58 GeV)

– Target luminosity: ~81035 cm-2s-1

• Belle II detector– Refurbishment of all sub-

detectors– 40 times higher luminosity– Faster readout


Silicon vertex detector

413th February 2013

Belle II SVD:• 4 layers of 6 inch DSSDs• Radii 38 to 135 mm• Readout: APV25

– 40 MHz / Tp= 50 ns– 192 cells analog pipeline– ENC = 250 e + 36 e/pF

• Minimize capacitive load!• Chips closest to sensors

strips chip-on-sensor• Keep material budget low

Belle (SVD2):• 4 layers of 4 inch DSSDs• Radii: 20 to 88 mm• Readout: VA1TA

– 5 MHz / Tp = 800 ns– no pipeline– ENC = 180 e + 7.5 e/pF

• Read out from edge of ladders– long pitch adapters– up to 3 ganged sensors


a) Top view:

APV25 chips(thinned to 100µm)

3-layer kapton hybrid

fanout for n-side (z)DSSD

single-layer flex wrapped to p-side (r-phi)

cooling pipeCF sandwich ribs

The Origami chip-on-sensor concept

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• CF reinforced ribs• 6” DSSD• 1mm Airex sheet• 3-layer flex circuit• Thinned APV25 (100µm)• Connection to Strips:

– PA on top side– wrapped PA for bottom

• Single cooling pipe

• Trade-off between material budget & SNR

• 0.55 X0 (averaged)

b) Side view (cross section): APV25(thinned to 100µm)

CF sandwich ribs(mech. support)

cooling pipe

DSSDAirexKapton

wrappedflex fanout

n-side

p-side


Belle II SVD Origami ladder

• Exploded drawing of a L6 ladder• 3 different Origami flex designs

– backward (-z), short tail– center (ce), for central sensor, long tail– forward (+z), routed along slanted sensor, complex shape

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Outline


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445 mm

125 mm

The evolution of Origami modules

• 2008: Introduction of concept• 2009: Feasibility shown with 4” DSSD module• 2010: First full-size module with 6” DSSD• 2011: Re-design to fit mechanical requirements of

Belle II SVD ladders

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• How to assemble ladder withtwo or more Origami flexes?

• Not possible sensor by sensor• Combined procedure required• 2-DSSD Origami module

– 2 HPK DSSDs– Two types of Origami flexes (-z and ce)– Single-layer PA0/PA1/PA2

Assembly of a 2-DSSD Origami module

913th February 2013


Attaching of pitch adapters (PA1 & PA2)

1013th February 2013

• Align PAs to p-side of sensor • Picked up with a vacuum jig• Apply mask and glue

– Ensures uniform thickness– Future: cutting plotter

• Place back onto sensor• Curing of glue


Attaching Origami flexes• Wire bonding p-side• Placing sensors onto an

assembly bench• Optical alignment

(not done this time)• Attaching Airex sheets

(in future: 1 per ladder)• Glue Origami PCBs

– pre-assembled APV chips– first CE – then –z

• Wire bonding n-side


-zCE


Bend and glue PA1, PA2


• PA1 & PA2 have to be bent toward top side

• Micro positioner with vacuum head

• Apply glue using masks• Pre-bend PA and align

vacuum head• Align PA to APV and

lower down• Glue curing• Followed by ~2500 wire

bonds

Custom vacuum nozzle


Attaching CF ribs• Mount ribs on jig• Place rib jig onto

assembly bench• Dispense glue• Place sensors

onto ribs• Distance given by

precise spacers• Cure glue• Remove spacers

and lower down assembly bench



Outline




Cooling of Origami APV chips


Cooling pipe

• ~10 W per ladder• Efficient CO2 cooling• Single cooling pipe for several

ladders– Little space for connections– Outer 1.6 mm

• Custom fixture to hold the pipe


Cooling contact requirements


• Re-mountable cooling pipe (no glue …)• Easy and safe mounting (bond wires …)• Avoid stress at sensor (thermal expansion)• Efficient heat transfer

– large contact area– compensate height differences of APVs– thermally conductive gap pads

• Electrically isolating• Radiation hard material


Thermally conductive gap pad• Heatload/APV: 0.35W• Coolant temperature: -20°C• Tube:

– stainless steel AISI 316L – wall thickness 100μm

• Gap pad: 86/125 Keratherm– λ [W/mK]: 1.5W/mK– Very soft, 1mm thick– Radiation hardness was

tested in October 2012

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Pipe clampHinge clamp:• PEEK G450• micro water jet cutting

– fabrication tolerance: 0.01 mm– Max. wall thickness: 20 mm– Min. inner radius:

0.1 mm

• Disadvantage: 2 parts• Prototypes tested on

2-DSSD module

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Cooling pipe mounting• Clamp bases glued

onto Origami PCB• Keratherm strips

placed onto APV chips

• Pipe put into camp bases

• Clamps closed



Final Module with cooling pipe



Improved version of clamp


• Material: PEEK• Improved shape• Single part• Clamp force: ~3 N• Prototypes tested

on dummy• Works well• Easy to assemble

22VCI 2013, C. Irmler (HEPHY Vienna)

Performance of CO2 cooling

13th February 2013

•Temperature measured at 4 locations of the 2-DSSD module•Stable operation for ~18 hours•Nominal temperature: -20°C•All temperatures within precision of probes no warming of coolant•Efficient heat transfer between chips and pipe (coolant)

Tem

pera

tur [

°C]

Time

Module InletModule OutletOrigami –zOrigami ce


Beam test performance• Beam test performed @ CERN SPS in October 2012• 120 GeV/c (mainly pions)• Module operated with CO2 cooling at -20 °C• Signal-to-noise ratio:


CLW Origami -z Origami cep n p n

1 15.0 29.7 16.7 19.42 11.5 15.6 12.8 10.1

3+ 11.3 14.6 12.4 11.7weighted avg. 12.6 21.7 13.7 14.2

• Many noisy channels due to wire bonding problems (new wire bonder)• Origami –z performed well (compared to single-sensor modules)• Origami ce suffered from noisy channels


Outline




Summary• Origami chip-on-sensor concept

– A low mass on-chip readout for 6” DSSD (0.55 X0 avg.)– Feasibility proven by several prototypes– Will be utilized for the Belle II SVD– Assembly procedure shown for a 2-DSSD module

• Two-phase CO2 Cooling:– Single tube for several ladders– Design and prototypes of tube clamp available

• Beam test @ CERN in October 2012• Ladder production scheduled for autumn 2013!


26VCI 2013, C. Irmler (HEPHY Vienna)

Thank You

13th February 2013


Backup Slides



Belle II SVD


APV25 chips

Cooling pipe

Origami ladder

Sensor underneath flex circuit

Pitch adapter bentaround sensor edge

End ring (support)


Team

K. Kamesh (TIFR), C. Irmler (HEPHY), Y. Onuki (Tokyo U.), K. Negishi (Tohoku U.)


E. Kato(Tohoku U.)

N. Shimizu(Tokyo U.)


Origami PCBs

3 types of 3-layer Origami PCBs:– backward (-z), short tail– center (ce), for central sensor, long tail– forward (+z), routed along slanted sensor, complex shape


-z

ce

+z


Pitch Adapters

• All available in single- and double-layer designs

• PA0: short, n-side, glued onto Origami PCB

• PA1: first half of p-side strips

• PA2: second half of p-side strips


Bond pads of single-layer PAs


Attaching Airex

• We used one piece per sensor• Later we will use a single sheet per ladder


12

3 4


Attaching Origami hybrids

1. Aligned CE to sensor2. Lifted it with Origami jig3. Applied glue4. Put back onto assembly bench5. Waited until glue has been cured6. Removed Origami jig7. Aligned –z to sensor8. Repeated from step 2.



Attaching Origami CE


1 2

3

4

5


Attaching Origami -z



Bend and Glue PA1, PA2 – Apply Mask


4: flatten glue

2

3: dispense glue

1: apply mask

5: remove mask


Final Module in Frame


Top and bottom views (w/o cooling pipe)

Documents

A Low Mass On-chip Readout Scheme for Double-sided Silicon Strip Detectors