Construction and Status of the Origami Module Prototype

C. Irmler, M. Friedl

HEPHY Vienna

Contents

• SuperSVD & Origami Concept • APV25 Thinning • Origami Hybrid • Module Assembly • Open Issues • Summary • Outlook

8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 2

SuperSVD Layout

20 [cm] 10 layers 6 5 4

4 layers of double sided strip sensors

0 3 1+2

Double-layer of DEPFET pixels

-30 -20 -10 0 10 20 30 40 [cm] • Tentative geometry  optimization is underway • New central pixel double-layer using DEPFET (see PXD session) • 4 strip layers of 6” DSSDs

(see talk by M. Valentan)

• Every sensor is

read out individually

to maintain good SNR – red: Origami chip-on-sensor concept – green: read out by conventional hybrid 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 3

Origami Chip-on-Sensor Concept

pit ch adapt er (int egrat ed int o flex) cooling pipe APV25 t hinned down t o 100µm Zylon rib Flex (100µm) Rohacell (1000µm) sensor (300µm) (drawing not to scale) • Thinned APV25 with flex circuit (Kapton) sits on sensor • Providing shortest possible connections to the strips  high SNR 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 4

• • •

Sketch of the Outermost Ladder (Layer 6)

Composed of 5 x 6” double-sided sensors Center sensors have Origami structure Border sensors are conventionally read out from sides ca. 60cm Structural element (Zylon) Cooling pipe Electronics for border sensor Connector (Nanonics) Flex circuits Electronics for border sensor Cooling block (end ring) 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 5

APV25 Thinning

• One wafer (319 good dies) thinned down from 300 µm to 106 µm and diced by French company EDGETEK / WSI • Received 314 good dies (5 lost = 98.4% yield) • 16 thinned APVs mounted onto 4 hybrids • Compared to 1 hybrid with 4 standard APVs Thinned APV25

Measurement Results:

• All APVs show similar signal and noise figure • Proper calibration curve • No measurable differences between normal and thinned chips Standard APV25 

Thinning has no effects on APV functionality and signal quality!

8 July 2009 APV25 Calibration Curve 3rd Open Meeting of the Belle II Collaboration, C. Irmler 6

Origami Hybrid – Final Layout

2 p-side APV chips 4 n-side APV chips 2 p-side APV chips Connectors (on both sides) 8 July 2009 Animal farm (mascots of creators) Flex fanouts to be Wrapped around the sensor edge • •

3-layer

flex hybrid design

p- and n-sides

are separated by 80V bias • n-side

pitch adapter

is integrated in hybrid 3rd Open Meeting of the Belle II Collaboration, C. Irmler 7

Origami Hybrid - Flexes

8 July 2009 • • • • • 3 pcs. of each type ordered at

CERN

PCB workshop in Feb. 09 Delayed reception of parts: – Hybrid: 22 April – Fanouts: 6 June Module assembly started very late at 10 June.

Not enough time to finalize module before Belle II GM However, assembly is in progress 3rd Open Meeting of the Belle II Collaboration, C. Irmler 8

Origami Hybrid – PCB Quality

• We faced some problems – A couple of bad vias (cured by soldering thin wires) – Some bad integrated fanouts (see photo below) – Bad bondability of the integrated fanout 8 July 2009 Good Bad 3rd Open Meeting of the Belle II Collaboration, C. Irmler 9

Module Assembly Step 1

• • SVD 3 Hamamatsu DSSD top side: 152 µm pitch (z) bottom side: 50 µm pitch (rφ) 8 July 2009 • • • • •

Gluing fanouts onto bottom side

Custom jig (porous stone inlay) for gluing and wire bonding Two component epoxy paste adhesive Araldite® 2011 Microscope used to align fanouts against sensor and hybrid Distance between flexes is important 3rd Open Meeting of the Belle II Collaboration, C. Irmler 10

Module Assembly Step 2

• • • •

APV25 chips are glued onto the Hybrid

Two component conductive adhesive Alignment under microscope Steps 1 & 2 can be performed in parallel 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 11

Module Assembly Step 3

• • • •

Wire bonding between fanouts and sensor

Fully automated bonder F&K Delvotec 6400 Processing of bottom side is finished everything worked fine 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 12

Module Assembly Step 4

Gluing hybrid onto Rohacell foam

(can be done in parallel with step 3) 8 July 2009

Hybrid is kept up by tape

1. Cutting out Rohacell 2. Applying glue 3. Placing hybrid onto Rohacell 4. Adjustement 5. Putting weights to keep flat

There must be sufficient glue underneath bond pads!

Rohacell held by vakuum

3rd Open Meeting of the Belle II Collaboration, C. Irmler 13

Module Assembly Step 5

•

Flip sensor and fanouts

• Using another jig  jig2 • Jigs are stuck together with 3 alignment pins • Connect jig2 to vacuum • Turning over • Plug off vacuum from jig1 • Remove jig1 • Further assembling has to be done on jig2 • Fanouts are more rigid than expected • We bent and fixed them in order to force their final form 8 July 2009 2 openings to protect bottom side bond wires 3rd Open Meeting of the Belle II Collaboration, C. Irmler 14

Module Assembly Step 6

• Wire bonding of

APV25 power and control

lines bottom APV25 •

Electrical test of hybrid

– some bad vias – repaired with thin wires – one APV with I2C failure • Hybrid PCB design is okay • 7 of 8 APV chips are working well • Excellent internal calibration results top APV25 8 July 2009 APV25 calibration curves of Origami hybrid 3rd Open Meeting of the Belle II Collaboration, C. Irmler 15

Module Assembly Step 7

• Gluing the hybrid onto top side of sensor • Aligning pitch adapter to strips on sensor • We also tried to bend the fanouts and checked their alignment – seems to be okay – probably a mechanical tool for alignment and gluing of fanouts will be necessary – softer fanouts for SVD production preferable – single layer design by other company (Casio?) 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 16

Module Assembly Step 8

• Until this point there were no problems which could not be solved • Next task: connecting Origami to sensor by wire bonding – No matching bond parameters could be found – Bonds on integrated pitch adapter didn’t attach • Possible Reasons: – To little glue underneath the bond pads?

– Bad gold coating of pads?

– ... something else?

– Has to be investigated!

– It already worked well with the Flex-Module in 2006 • Workaround: – We checked the bondability of the pitch adapter of another Origami sample  seemed to be OK – We cut it out, glued it onto the integrated one and tried to bond again 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 17

Module Assembly Step 8 continued

• Yesterday evening we received really

bad news

from Vienna: – A corner of the sensor was broken during the second bonding attempt.

– We actually do not know the reason for this accident.

– Was the sensor weakened by too many attempts to bond at the same location in order to find working parameters?

– Malfunction of the bonding machine?

Usually it stops automatically when anything goes wrong.

– … something else?

• • Anyway, this module is damaged and can not be finalized 

R.I.P.

We have to investigate the reasons once we are back in Vienna.

8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 18

Module Assembly Step 8 continued

Photos of the broken sensor: 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 19

Module Assembly – Open Issues

• Bonding of sensor and hybrid – principal bondability proven after the accident (see photo below) • Bend and glue the fanouts onto the top side of the module • Connect the APV frontend with the pitch adapters by wire bonds • We will use the damaged module for tests of the above tasks • Mounting of cooling pipe and support structure • Mechanical frame for beam test 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 20

Summary

• First attempt to assemble an Origami module • After delayed delivery of flexes, assembly has only been started on 6 June • Good progress since then • Some issues with quality of flexes – A couple of bad vias – Some cases of bad integrated fanouts – Bad bondability of the integrated fanout – We shall receive new and hopefully better samples within the next two weeks from the CERN workshop • Accident during bonding  sensor is broken • We have to restart from the beginning… 8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 21

Outlook

8 July 2009

We don’t give up!

3rd Open Meeting of the Belle II Collaboration, C. Irmler 22

BACKUP SLIDES

8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 23

Origami Hybrid – Flexes 2

8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 24

Module Assembly Step 7a

8 July 2009 3rd Open Meeting of the Belle II Collaboration, C. Irmler 25