alice silicon strip detector module assembly with single-point tab interconnections 1) introduction...

ALICE Silicon Strip Detector Module Assembly with Single-Point TAB Interconnections

1) Introduction2) Collaboration3) ALICE SSD module4) Assembly phases5) Single-Point TAB interconnections6) Bond quality assurance

a) pull testsb) bond breaking mechanisms and bond strengthsc) electrical tests

7) Thermal cycling studies8) Assembly status

M.Oinonen at LECC 2005, Heidelberg, 14th of September 2005

Si strip detectors at ALICE ITS

ALICE ITS: 2 pixel, 2 drift and 2 strip (SSD) detectors layers, 1698 SSD

modules with 2.6 106 channels, > 7 106 bonds

ALICE ITS

Minimization of mass: thin and flexible structures used with polyimide-Al

cables

Flexible interconnections based on Ukrainian technology (space and military industry) strong role of Ukrainian institutes and industry

pixel

strip

drift


ALICE SSD Collaboration

IreS, Strasbourg: HAL25 front-end

chips, sensors, module assembling, database, general coordination

NIKHEF & Utrecht: general coordination & quality control, design of cables, test setups,

module folding, module readout Kiev & Kharkov:

cable and subhybrid design & production,

manpower

Helsinki: module assembling, long-term

reliability studies

Trieste: module assembling, sensors

and sensor tests

Nantes: ladder assembling


Assembly phases / 1

Kharkov

Helsinki, Strasbourg,

Trieste


Assembly phases / 2


Trieste


ALICE Silicon Strip Detector module

Thin and flexible interconnections with Al-polyimide cables

Readout via flexible hybrids on both N and P side

Double-sided sensor with 2 x 768 channels = 1536 detectors

2 x 6 HAL25 front-end Chips on Flex (CoF), 128 ch’s each


Assembly phases / 3: Folding

M.Oinonen at LECC 2005, Heidelberg, 14st of September 2005

To be able to install the modules

in ladders

Challenges the quality of spTAB interconnections !


Trieste

Production line equipment / Helsinki(see: http://www.hip.fi/research/detlab/index_en.htm)

- semiautomatic bonder (Kulicke&Soffa 4523AD)- automatic bonder (F&K Delvotec 6400)

- movable (XYZ) & rotary () bond head flexible- 200 x 150 mm bonding area with 1 m resolution- ultrasonic TAB and wire bonding (10 000 wires)

- vacuum oven - ovens (Memmert ULP 400 and UM 200)- X-Y-Z table with Labview control- pressure dispensers- microscopes (50 x – 500 x)- N2 chambers for storing

line for ALICE SSD module production


Single-point Tape-Automated Bonding (spTAB)

Bond

Etched window

Bonding pad

Al lead

Chip/sensor

Polyimide

One bond at a time by using ultrasonic bonding

machine and a special wedge

Modified wirebonders used with 60 kHz US

frequency:

F&K Delvotec 6400 (aut)K&S 4523AD (man)


Bond quality assurance / methods

1) Pull tests

a) Manually with a gramometerb) PC controlled with a special setup

3) Electrical tests

Operation of the protection diodes in the HAL25 chips (chip bonds)Operation of hybrids (hybrid bonds)Noise characteristics (sensor bonds)

2) Optical 3D tests

Understanding of the bond failure mechanismsSpin-off: search for nondestructive & 3D techniques for quality control


Quality assurance / pull tests

1) Chip & cable with one bond2) Vacuum stage

3) Pull hook with step motor control

4) PC controlled scale

Both manual and PC controlled pull tests give consistent results


Quality assurance / pull test results

Bond type Trace width (m)

Trace thickness

(m)

Max. pull strength (gf)

High quality bonds (gf)

Chip i/o 36 14 8-9 > 5-6

Sensor 36 14 8-9 > 5-6

Subhybrid 80 14 15-16 > 8-9

Experience: such a high quality bond has less probability to fail under folding operations and thermal cycles compared to the bonds with

lower pull strength


Quality assurance / failure modes

a) Lift-offs and heel breaks in pull testsb) Weak bonds or non-attachments during mass production due to contaminants or cable geometry (bending, narrow bond openings)


Spin-off developments

Scanning White-Light Interferometer in fast and non-destructive bond quality control [1]

[1] H. Seppänen et al., Scanning White-Light Interferometry in Quality Control of Single-Point Tape Automated Bonding, in the Proceedings of the SPIE International Symposium Photonics North, September

27-29, 2004, Ottawa, Canada.


Quality assurance / optical studies

Excess of US power or bond force

overdeformation small height, low pull strengths

heel breaks / open circles

bond height (m)

-2 0 2 4 6 8

bond

pul

l str

engt

h (g

f)

0

2

4

6

8

10

lift-offsheel breaks

a) lack of US power / bond force

b) contamination / geometry problem

high bonds, low pull strengths

lift-offs / closed circles

Both modes present at the maximum pull strength


Quality assurance / lift-off patterns

Largest strength reached when part of the trace is left attached on the pad:typical for a good spTAB bond in ALICE SSD application

Selection of lift-off patterns used to develop the bond process for the SSD chip bonds (F&K Delvotec 6400).

US power (m.u.) 20 25 30 35

Lift-off pattern

Failure type lift-off lift-off heel-break/(partial lift-

off)

heel-break/(partial lift-

off)

Pull strength (gf) 3,5 6,0 9,0 8,5


Quality assurance / electrical tests for Helsinki chip bonding process

On average 99,74 % bonding yield after first-go (incl. dip!)Dip of 92% due to contaminations and cable geometry (new facility)

Date

01.0

6.20

04

01.0

7.20

04

01.0

8.20

04

01.0

9.20

04

01.1

0.20

04

01.1

1.20

04

01.1

2.20

04

01.0

1.20

05

01.0

2.20

05

01.0

3.20

05

01.0

4.20

05

01.0

5.20

05

01.0

6.20

05

01.0

7.20

05

01.0

8.20

05

Bo

nd

ing

yie

ld (

%)

90,0

92,0

98,8

99,2

99,6

100,0

100,41st-go bonding yield


1) Bond failures tend to start from the end of the

bond rows

Thermal expansion most probable cause

Thermal cycling studies: induced failures

2) Bonds made during “dip” of 92% yield fail

earlier

Bonding quality DOES matter !


Thermal cycling studies for Time-to-First-Failure (TTFF)

Chip bonds Framed chips

Subhybrids Subhybrids

Test location FMI/

HIP

FMI/

HIP

SRTIIE HIP

samples 4732 26 2 6

Ttest (C) 100 100 160 65

Ncycles >782 >782 >150 >389

m 3.5 3.5 2 2

TTFF(years) >>20 >>20 >9.6 >12.3

FMI = Finnish Meteorological Institute, HelsinkiHIP = Helsinki Institute of Physics, Helsinki

SRTIIE = Scientific Research and Technological Institute of Electronics Engineering, Kharkov

Note! JEDEC JEP122B

consistentlyfollowed in

these studies


ALICE SSD framed chip production(10th of Sept, 2005)

Quality Q = 100- defected channels

Yield defined as components having Q > 98

Location Bonded Yield (%)

HEL 5659 89.6

STR 4761 88.6

TRI 4600 90.6

total 15020 89.6


The same yields in all the sites!

ALICE SSD hybrid production (10th of Sept 2005)

Quality Q = 100- defected channels

Yield defined as components having Q > 90

Location Bonded Yield (%)

HEL 868 97.4

STR 349 87.1

TRI 631 95.2

total 1848 94.7


ALICE SSD module production (10th of Sept 2005)

Test setup just taken in use within the

collaboration: no reliable yield yet available !

Losses most probable, since the most challenging operations ahead: folding,

ladder assembly etc.

Anyway, success in chip & hybrid assembly

shows the spTAB process OK


alice silicon strip detector module assembly with single-point tab interconnections 1) introduction...

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