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Air based self-assembly of silicon chips on foils
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Transcript of Air based self-assembly of silicon chips on foils
1Airflow based self-assembly of silicon chips on foils | 13
Air based self-assembly of silicon chips on foils
Name: B. van LeeuwenCoach: Dr.Ir. M. TichemProfessor: Prof.dr. U. StauferSpecialisation: Production TechnologyConcern: Holst CentreCoach: Prof. Andreas Dietzel, PhDDate: 08-07-2009
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Contents
• Introduction• Holst centre• Micro assembly
• Problem description• Simulation
• Dynamic simulation using COMSOL
• Dynamic simulation using Matlab• Practical test
• Test setup
• Test results• Applicability• Results
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Introduction
•Joint venture of TNO and IMEC-NL•Research in future products
• System-in-foil: Low cost, flexible electronics which can be integration in disposable every day products
Holst centre
Source: Holst Centre
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Introduction
• Problems appearing in micro assembly:• Scaling effect sticking effect
• Gripping and grasping difficult (delicate parts):• Solution Self-assembly
• Self-assembly: • Processes in which a disordered system of pre-existing
components forms an organized structure or pattern.
(http://en.wikipedia.org/wiki/Self-assembly)
• Self-assembly can be based on different physical phenomena:• For example: Mechanical, Fluidic or Gas based processes
Micro assembly
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Problem description
• Intelligent package, produced on roll-to-roll production
• Placement of flexible chips on flexible foil
• Chip placed on first foil, than laminated with second foil• First foil makes placement possible• Second foil takes care of electrodes
and connections
Context
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Problem description
• Multi scale issue (large foil, small chips, accurate positioning)
• Ultra low cost, high volume production process
Solution: Coarse placement followed by self-assembly
• Only air basedassembly treated
Target loca tion
F ina l positionFo il on ro ll
Context
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Problem description
• Air flow based self-assembly• Holes in foil will allow air through foil
by backside overpressure.• Velocity gradient above surface of
foil.• Chip will float and drift to final target
location.• Different designs possible
•Main problem• Design a foil in a way that: the
chip drift to the target location by airflow
Context
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Simulation
• 2D FEM simulation, solving the Navier-stokes equations using COMSOL.
• For different foil designs (velocity profiles)• Obtaining static data
• 2D motion, solving the equations of motion using Matlab.• Data form COMSOL stored in lookup tables• Motion calculated using ODE solver• Motion displayed
Dynamic simulation using COMSOL and Matlab
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Simulation
The inlet velocity is imposed at the lower boundary and is defined by the friction of the nozzles:
Dynamic simulation using COMSOL
4
121
1
1
( ) ( )128 ( )
In which:
hole diameter
pressure underneath foil
( ) pressure above foil
thickness of foil
( ) pitch between holes
dynamic viscosity of air
dv p p p x
L b x
d
p
p x
L
b x
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Simulation
Static simulation implemented for a certain chip position
Dynamic simulation using COMSOL
0
0
The force in 2D on the underside of the chip:
The moment on the chip:
1 2
l
l
NF p dx m
M l p s dx N
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Simulation
• Storing the obtained data lookup tables, dependent on x, y and φ
• Multiple lookup tables for:• Forces and moments• Different velocity profiles.
• Not all angle, y-position combinationspossible because of geometry
Dynamic simulation using Matlab
X
Y
P hi
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SimulationDynamic simulation using Matlab
2 2
( , , ) sinF
( , , ) cosF
M
In which:
Moment of inertia [kgm ] (source:[D])3
Gravity force on chip [N]
Lift force on c
lift
x
liftgy
lift
z
g
lift
F x ym x x
mF x y
m y y Fm
MJ
J
mJ l
F m g
F
hip obtained from COMSOL [N]
Moment on chip obtained from COMSOL [Nm]liftM
The equations of motion can now be formulated
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SimulationDynamic simulation using Matlab
Solving the equations of motion leads to the moving chip.
0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01
-1
0
1
2
3
4
5
6
x 10-3 Motion of chip t = 2.029
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Practical test
Features of test setup• Overpressure in box by fan• Foil attached on top• Pressure measurement for feedback• Events observed by camera
Test setup
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ApplicabilityPractical applicability
Foil
A ir pocketA ir supply
Self alignm entprocess
Aligned chip
Movingdirection
Chip supply onreel
• Integration possibilities• Chip supply• Chip alignment• Chip fixation
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Results
• Working simulation software• Dynamic simulation using an array of static FEM calculations
• Practical proof of concept• Design and build of test setup• Successful testing of foil design
• Practical applicability• Possible integration with other production steps• Manny possibilities
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Simulation (backup slide)
Lookup tables for damping in y-direction:• New forces calculated with initial speed• New force subtracted from force without initial speed• Force linearization round zero becomes damping force
Dynamic simulation using COMSOL
-0.01 v[m/s]
F lift
F lift_v1
F(v)
F [N ]
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Calculation (backup slide)
Chip levitation height, foil 7 comparison
0
50
100
150
200
250
300
0 100 200 300 400 500 600
Pressure [pa]
levi
tati
on
hei
gh
t [u
m]
Foil 7, measurement
Foil 7, calc. without impulse
Foil 7, calc. with impulse
Foil 7, calc. FEM