Construction and Status of the Origami Module Prototype C. Irmler HEPHY Vienna.

Construction and Status of the Origami Module Prototype

C. Irmler

HEPHY Vienna

2Christian Irmler, HEPHY Vienna10 July 2009

Contents

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


SuperSVD Layout

0

0

10

1+23

45

6[cm] layers

[cm]

20

-10-20-30 10 20 30 40

• Tentative geometry optimization is underway• New central pixel double-layer using DEPFET• 4 strip layers of 6” DSSDs• Every sensor is read out individually to maintain good SNR

– red: Origami chip-on-sensor concept– green: read out by conventional hybrid

Double-layer of DEPFET pixels

4 layers of double-sided strip sensors


Origami Chip-on-Sensor Concept

• Thinned APV25 with flex circuit (Kapton) sits on sensor

• Strips of bottom side are connected by short flex fanouts, which are wrapped around the sensors edge

• All readout chips are on top side in a row single common cooling pipe

• Providing shortest possible connections to the strips high SNR

(drawing not to scale)

APV25(thinned to 100µm)

zylon ribcooling pipe

DSSDRohacellKapton

zylon rib

APV25 cooling pipe

4-layer kapton hybrid

integrated fanout(or: second metal)

DSSD

single-layer flex wrapped to p-side


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

Cooling block (end ring)

Connector (Nanonics)

Structural element (Zylon) Cooling pipe

Flex circuits

Electronics for border sensor

Electronics for border sensor

ca. 60cm


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

Measurement Results:• All APVs show similar signal and noise figure• Proper calibration curve• No measurable differences between normal

and thinned chips

Thinning has no effects on APV functionality and signal quality! APV25 Calibration Curve

Thinned APV25

Standard APV25


Origami Hybrid – Final Layout

4 n-side APV chips

2 p-side APV chips 2 p-side APV chips Connectors(on both sides)

Flex fanouts to beWrapped aroundthe sensor edge

• 3-layer flex hybrid design• p- and n-sides are

separated by 80V bias• n-side pitch adapter is

integrated in hybrid

Animal farm (mascots of creators)


Origami Hybrid - Flexes

• 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 finalized yet


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– New samples are underway

Good Bad


Module Assembly Step 1

• 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

SVD 3 Hamamatsu DSSD

• top side: 152 µm pitch (z)

• bottom side: 50 µm pitch (rφ)



• APV25 chips are glued onto the Hybrid

• Two component conductive adhesive

• Alignment under microscope

• Steps 1 & 2 can be performed in parallel



• Wire bonding between fanouts and sensor • Fully automated bonder F&K Delvotec 6400• Processing of bottom side is finished• everything worked fine



Gluing hybrid onto Rohacell foam (can be done in parallel with step 3)

Rohacell held by vakuum

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 flatThere must be sufficient glue

underneath bond pads!


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

2 openings to protect bottom side bond wires



• Wire bonding of APV25 power and control lines

• 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

bottom APV25

top APV25

APV25 calibration curves of Origami hybrid



• 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?)



Origami module ready for bonding n-side (top) strips

• Until this point there were no problems which could not be solved • Next task: connecting Origami to sensor by wire bonding


Module Assembly Step 8 continued

• 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



• Mid of this week 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.



Photos of the broken sensor:


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


• 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…

Summary


Outlook

We don’t give up!


BACKUP SLIDES


Origami Hybrid – Flexes 2


Module Assembly Step 7a

Construction and Status of the Origami Module Prototype C. Irmler HEPHY Vienna.

Documents

Transcript of Construction and Status of the Origami Module Prototype C. Irmler HEPHY Vienna.