origami chip-on-sensor design: progress and new developments 19th september 2012 twepp 2012, c....

Origami Chip-on-Sensor Design:Progress

andNew Developments

19th September 2012

TWEPP 2012, C. Irmler (HEPHY Vienna)

TWEPP 2012, Oxford University


Outline

• Introduction• Status• 2-DSSD Module• Cooling• Summary

219th September 2012


Motivation

• Belle II SVD ( M. Friedl)

• Super KEKB– 7 GeV e- on 4 GeV e+

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


~1 km in diameter

Super KEKB Belle II

Linac

About 60km northeast of Tokyo

• SVD Requirements:– Twice as large– Low material budget– Low occupancy– Fast readout (APV25)– High SNR– Chips closest to sensor

strips

Origami Chip-on-Sensor Concept


The Origami Chip-on-Sensor Concept


• CF reinforced ribs• 6” DSSD• 1mm Airex sheet• 3-layer polyimide PCB• Thinned APV25 • Connection to Strips:

– PA on top side– wrapped PA for bottom

• Single cooling pipe

• Trade-off between material budget & SNR

• 0.55 X0 (averaged)

a) Top view:

APV25 chips(thinned to 100µm)

3-layer kapton hybrid

fanout for n-side (z)DSSD

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

cooling pipeCF sandwich ribs

side view(below)

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


APV25 chips

Cooling pipe

Origami ladder

Sensor underneath flex circuit

Pitch adapter bentaround sensor edge

End ring (support)


Belle II SVD

• 4 layers of 6” DSSDs• Radii: 38/80/105/135 mm • 2/3/4/5 sensors per ladder• Origami PCBs in L4-6• L3 & edge sensors read out by

conventional hybrids• 3 different PCB designs



Outline




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


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, beam test with CO2 cooling, …



2012

• How to assemble ladder withtwo or more Origami PCBs?

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

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


2-DSSD Origami Module


Outline




Assembly Location

• Kavli IPMUInstitute for the Physics and Mathematics of the Universe

• Belongs to Tokyo University

• Kashiwanoha Campus• New clean room and lab

for L6 ladder assembly


~30km north of Tokyo


Team

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


E. Kato(Tohoku U.)

N. Shimizu(Tokyo U.)


Attaching of PA1 & PA2


• Almost unchanged procedure• PAs were aligned to sensor and

then picked up with a vacuum jig• New: mask to apply glue• Ensures uniform thickness• Future: cutting plotter

mask samples

Graphtec CE5000-60


Attaching Origami PCBs• 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


• Already established procedure

• Micro positioner with vacuum head

• Masks to dispense glue• Pre-bend PA and align

vacuum head• Align PA to APV and

lower down• Glue curing• Followed by ~2500 wire

bonds


Final Module in Frame


Top and bottom views (w/o cooling pipe)


Outline




Cooling Pipe


Cooling pipe

• Single cooling pipe forseveral ladders– Little space for connections– Outer 1.6 mm

• Custom fixture to hold the pipe


Cooling Contact – Pipe on APV25 Chips

Requirements:• Re-mountable cooling coil (no glue …)• Easy and safe mounting (bond wires …)• Electrically isolating• Radiation hard material• Avoid stress at sensor• Efficient heat transfer

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



Thermal simulationsThermally conductive Gap Pads

• Heatload/APV: 0.35W• Coolant temperature: -20°C• Tube: stainless steel AISI 316L, wall 50μm

• Gap pad: 86/125 Keratherm• λ [W/mK]: 1.5W/mK• Very soft, 1mm thick• Radiation hardness? Will be tested in October

19th September 2012 22


Pipe Fixture – First Concepts

• Prototype 'big' screw clamp • One part clamp

Screws Too bulkyStructure is fragileand the contactsurface is small

Large force necessary to snap tube intothe clamp



Pipe Fixture – Improved Design

Hinge clamp:• PEEK G450• micro water jet cutting

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

0.1mm

• Disadvantage: 2 parts• First prototypes delivered• Used on 2-DSSD module



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


27TWEPP 2012, C. Irmler (HEPHY Vienna)

Performance of CO2 Cooling

•Three 6” Origami modules were tested in a 120 GeV beam (October 2011)•Stable operation of CO2 cooling system for 3 days•The sum of bias currents of sensors decreases from >70µA to ~20µA

19th September 2012

0 1000 2000 3000 4000 5000 6000 70000

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

time [s]

bia

s cu

rren

t [n

A]

Bias current of all

3 modules vs. time

CO2 system

off CO2 system on

24h

4h

Pressure reduction for lower temperature


2-DSSD Origami Module Performance

• A week ago: first source test of new module with CO2 cooling

• So far the module works well • Ready for beam test in October


preliminary


Outline




Summary

• Origami chip-on-sensor concept adapted to fit requirements of Belle II SVD ladders– 6” sensor, three flex designs

• Assembly procedure extension to full ladder– in progress

• Design and first prototypes of pipe fixture• Recently assembled a 2-DSSD Origami module• Beam test and irradiation in October 2012• Start of ladder production scheduled for

summer 2013!


31TWEPP 2012, C. Irmler (HEPHY Vienna)

Thank You

19th September 2012


Spare Slides



Improved Version of One Part Clamp



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 sensor

2. Lifted it with Origami jig

3. Applied glue

4. Put back onto assembly bench

5. Waited until glue has been cured

6. Removed Origami jig

7. Aligned –z to sensor

8. Repeated from step 2.



Attaching Origami hybrids


1 2

3

4 & 5


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


Pre-bend and attach stopper


Stopper for PAs

pre-bended PA

6

align vacuum head to assembly bench and PA

design concept of PA stopper


Align PA to APV chips


7: PA to APVs

8: lower down

9: cure glue

Bond pads visible

Thermally conductive Gap Pad• Responsible for Origami cooling: Annekatrin Frankenberger • Selection of thermally conductive materials with different properties.

42TWEPP 2012, C. Irmler (HEPHY Vienna)19th September 2012

86/125Keratherm

2000S40Bergquist

575-NS Parker Chomerics

Sil Pad 800Bergquist

λ [W/m K] 1.5 2.0 1.2 1.6

Hardness [Shore 00]

10 30 70 Shore A 91

Thickness [mm] 0.5 - 5 0.5 – 3.1 0.5 – 2.5 0.1

Silicone x x -- x

Radiation hardness

? ? ? x

Gamma irradiation tests (@ Mol in October)


Thermal simulationsThermally conductive Gap Pads

• Heatload/APV: 0.35W• Coolant temperature: -20°C• Tube: stainless steel AISI 316L, wall 50μm

• Gap pad: Sil Pad 800 Bergquist• λ [W/mK]: 1.6W/mK• Hardness Shore A: 91• Thickness: 0.1mm

good contact? Adjusting unevennes?



Tube fixtureDisplacement simulation

Necessary displacement UX = -0.4mm

Acting force 1.4N


origami chip-on-sensor design: progress and new developments 19th september 2012 twepp 2012, c....

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