Prestazioni elettromagnetiche di materiali compositi e di plastiche

Corso di Elettrotecnica V.O.
Corso di Laurea di Ingegneria Aerospaziale
a.a. 2001-2002
• Prestazioni schermanti di pannelli in
materiale composito e di strutture scatolari:
ƒ risultati numerici
Prestazioni elettromagnetiche di
materiali compositi e di plastiche
con rivestimento schermante
ƒ risultati sperimentali
• Tecniche per il miglioramento delle
prestazioni schermanti di materiali
compositi e plastici
Prof. M.S. Sarto
1
Shielding effectiveness of infinite plane
CARATTERISTICHE DEL PANNELLO
MULTISTRATO
2
3
4
ε1
µ0
σ1
ε2
µ0
σ2
ε3
µ0
σ3
ε4 ε5
µ0 µ0
σ4 σ5
d2
d3
d = 1 mm
d4
120
100
εr1 = εr3 = 2
1
d1
[dB] 140
d1 = d3 = 0.2 mm
Multilayer panel
5
d5
2
σ1 = σ3 = 10 kS/m
80
d2 = d4 = 0.2 mm
εr2 = εr4 = 4
60
5 layers
1 layer
σ2 = σ4 = 50 S/m
d5 = 0.2 mm
40
10
εr5 = 3
4
10
6
10
8
10
10
frequency [Hz]
σ5 = 1 kS/m
Analytical ()
3
FDTD (- - -)
4
T = 15 ns
Analysis of 2D-configurations
18.6
18.6
y [m]
y [m]
0
0
n
L
n
Hz
ε 0 , µ0
Ey
Ey
∆t = 0.05 ns
L = 90 cm
∆x = 3 cm
Hz
-18.6
5-layers panel
-18.6
-18.6
• Incident TM plane wave
-1.2
0
x [m]
-0.6
18.6
0
0.6
∆t = 0.05 ns
9
y [m]
0
0
-9
∆x = 3 cm
-2
0
x [m]
-1
0
9
1
2
-9
-4
0
x [m]
-2
0
9
9
9
y [m]
y [m]
0
0
t = 100 ns
4
2
6
-9
-9
-9
4
2
Hz [mA/m]
Ey [V/m]
0
18.6
tr = 5 ns te = 200 ns L = 3 m ∆t = 0.05 ns ∆x = 3 cm
-9
-9
-2
t = 100 ns
9
y [m]
0
x [m]
Hz [mA/m]
5
L=3m
-4
1.2
Ey [V/m]
• Space- and time discretization defined by ∆x , ∆t
T = 5 ns
-18.6
0
0
x [m]
0.4
0.8
Ey [V/m]
7
9
1.2
-9
1.5
0
x [m]
9
1.75
2
Hz [mA/m]
t = 100 ns
8
T = 5 ns
∆t = 0.05 ns
L=3m
∆x = 3 cm
5-layers panel
ε 0 , µ0
L
Ey
9
9
y [m]
y [m]
0
0
n
L
-9
-9
-9
Hz
0
x [m]
θ = 45°
-2
0
-1
-9
9
1
-5
2
Ey [V/m]
0
x [m]
0
Hz [mA/m]
t = 100 ns
9
9
5
10
tr = 5 ns te = 200 ns L = 90 cm ∆t = 0.05 ns ∆x = 3 cm
5-layers panel
L
Ey
Hz
L
n
9
9
y [m]
y [m]
0
0
-9
θ = 0°
-9
-9
0
x [m]
L
-0.6
ε 0 , µ0
0
9
0.6
1.2
-9
1.55
Ey [V/m]
11
t = 100 ns
0
x [m]
9
1.85
1.65
1.75
Hz [mA/m]
12
T = 15 ns
5-layers panel
Ey
L
n
Hz
18.6
18.6
y [m]
y [m]
0
0
-18.6
-18.6
θ = 0°
L
-1.5
ε 0 , µ0
0
x [m]
18.6
0
1.5
CONFIGURAZIONE DI TEST
15
t = 100 ns
Ê iy = 50 kV/m ,
25
τ1 = 5 ns ,
τ2 = 200 ns
• FDTD grid:
70 cm
70 cm
Eiy
14
E yi (t ) = Eˆ yi [exp(− t τ 2 ) − exp(− t τ1 )]
i
30
4
2
• Incident EMP plane wave:
Hz
Ey
20
0
Hz [mA/m]
εmr = 4 , εfr = 2 , σf = 5 kS/m , ρf = 20% - 32%
70 cm
10
-2
-4
18.6
• Carbon fiber composite panel:
0.1 cm
30
0
x [m]
3D-FDTD analysis
carbon fiber
composite panel
35
-18.6
Ey [V/m]
13
5
∆x = 3 cm
ε 0 , µ0
-18.6
35
∆t = 0.05 ns
L = 90 cm
0°/ 90°/ 0°
∆x = ∆y = ∆z = 5 cm , ∆t = 0.083 ns
n
Hiz
15
16
EM field penetration inside the metalliccomposite box
Experimental analysis
Bounded-wave EMP simulator
Ey - open box
measured
antenna
2 (kV/m)/div
8
22 m
control
room
y
z
Hz
Ey
x
Ey [kV/m]
6
compositemetallic
box
n
computed
4
2
fiber optic cables
0
120 m
−2
−4
Useful volume of dimensions 8 m × 8 m × 8 m
100 ns/div
0
200
17
400
time [ns]
600
800
18
Ey - closed box
Hz - open box
measured
10 (V/m)/div
computed
30
measured
computed
Ey [V/m]
50 (A/m)/div
150
20
100
10
ρf = 32%
50
0
-10
100 ns/div
Hz [A/m]
ρf = 20%
0
0
200
400
time [ns]
600
800
100 ns/div
19
− 50
0
200
400
time [ns]
600
800
20
Induced current in the inner wire
Hz - closed box
open box
measured
5 (A/m)/div
computed
15
measured
Hz [A/m]
computed
2 A/div
12
ρf = 20%
10
I [A]
10
8
ρf = 32%
6
5
4
2
200 ns/div
0
0
400
800
time [ns]
1200
0
1600
−2
0
100 ns/div
200
400
time [ns]
600
21
22
SHIELDING EFFECTIVENESS OF METALLICCOMPOSITE ENCLOSURES
closed box
Ey field:
measured
[
computed
SE E (r; ω) = 20 log E yi (r; ω) E y (r; ω)
I [A]
0.2 A/div
]
1.6
[
ρf = 20%
1.2
0.8
]
E y (r; ω) = F E y (r; t )
i
Ey
ρf = 32%
0.4
Ey
0
200 ns/div
[
]
E yi (r; ω) = F E yi (r; t )
0
400
800
time [ns]
1200
1600
23
E yi (r; t )
i
E y (r; t )
i
i
Hz
Hz
without the metallic-composite
box
with the metallic-composite
24
box
800
Hz field:
[
SE H (r; ω) = 20 log H zi (r; ω) H z (r; ω)
90
]
[d B ]
SEE
60
[
[
]
]
S E (in d e fin ite p a n e l)
H z (r; ω) = F H z (r; t )
H zi (r; ω) = F H zi (r; t )
30
Ey
i
Ey
H zi (r; t )
i
H z (r; t )
0
i
i
Hz
Hz
without the metallic-composite
box
SEH
10
5
7
6
10
10
fre q u e n c y [H z ]
10
8
with the metallic-composite
box
25
Misure di SE con il metodo ASTM
26
SE campione in fibra di carbonio 1 mm (Sample2)
(guida d’onda coassiale)
120
1a misura
Sample1
Fibra di carbonio
2 mm
Sample2
Fibra di carbonio
1 mm
100
2a misura
3a misura
80
SE (dB)
Materiale
Spessore
60
40
Sample3
Sample4
Struttura a sandwich, fibra di vetro
1 mm, fibra di carbonio 2mm, fibra
di vetro 1 mm
4 mm
Fibra di carbonio
1.5 mm
20
0
27
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
2,0
Frequenza (GHZ)
28
Misure di SE con il metodo delle camere
riverberanti (presso NIST, Boulder , CO)
SE campione in fibra di carbonio 1,5 mm (Sample4)
120
1a misura
100
2a misura
SE (dB)
110
80
70
60
50
40
0,0
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
Materiale con cui sono realizzati
Spesso
re
Sample1
Campione di riferimento
(piatto di metallo)
Fibra di carbonio
2 mm
Sample3
Struttura a sandwich, fibra di vetro 1 mm,
fibra di carbonio 2 mm, fibra di vetro 1 mm
4 mm
Sample4
Fibra di carbonio
1.5 mm
Sample5
Fibra di vetro con retina in nastro di rame
1.5 mm
Sample6
Tessuto in gomma
0.5 mm
Sample3’
Struttura a sandwich senza fibra di vetro
sul bordo
4 mm
Sample2
3a misura
90
Campioni
2,0
Frequenza (GHz)
29
Fibra Carbonio d=1 mm (sample 2)
55
SE (dB)
50
45
SE(2) 1a misura
SE(2) 2a misura
SE(2) 3a mis+abs
SE(2) 4a mis+abs+steel-wool
SE(2) 5a mis+steel-wool
80
75
70
65
SE (dB)
60
30
Fibra in Carbonio d=1,5 mm (sample 4)
SE(2) 1a misura
SE(2) 2a misura
SE(2) 3a mis+abs
SE(2) 4a mis+abs+steel-wool
SE(2) 5a mis+steel-wool
65
1 mm
40
35
60
55
50
45
30
40
25
0
2
4
6
8
10
12
14
16
35
18
30
Frequenza (GHz)
0
31
2
4
6
8
10
Frequenza (GHz)
12
14
16
18
32
Tessuto in gomma d=0.5 mm (sample 6)
SE campione in fibra di vetro (sample5)
75
SE(2) 1a misura
SE(2) 2a misura
SE(2) 3a mis+abs
70
65
SE(2) 4a mis+abs+steel-wool
SE(2) 5a mis+stee-wool
55
SE (dB)
SE (dB)
60
50
78
SE(2) nastro di ram e in pos paral 2.5 cm
68
SE(2) nastro di ram e pos paral 0.5 cm
58
SE(2) nastro di ram e a griglia 0.25x0.5 cm
48
SE(2) nastro di ram e a griglia 0.25x0.25 cm
38
45
28
40
18
8
35
-2
30
0
2
4
6
8
10
12
14
16
Frequenza (GHz)
18
Sam ple1
Sam ple2
Sam ple3
Sam ple4
Sam ple6
Sam ple3'
90
80
SE (dB)
70
2
4
6
8
10
12
14
16
18
Frequenza (G H z)
34
ENHANCEMENT OF THE SE OF COMPOSITE
MATERIALS AND PLASTICS BY
DEPOSITION OF THIN FILMS
Valori di SE per i campioni in composito
100
0
33
• Dual Ion Beam Sputtering of thin films on
composite materials
• Innovative lightweight shields to reduce the
radiated emissions from PCBs
60
50
40
30
20
10
0
2
4
6
8
10
12
14
16
18
F requenza (G H z)
35
36
DUAL ION BEAM SPUTTERING OF THIN
FILMS ON COMPOSITE MATERIALS
OBJECTIVES
To improve the shielding performances of plastics and
composite materials:
• Metallization of plastic and composite substrates
• The Dual Ion Beam Sputtering (DIBS) technique
• Thin conductive coatings
• The experimental tests:
¾ SE
¾ Adhesion
¾ Abrasion
¾ Oxidation
• Minimum increase of weight
• Environmentally “clean” deposition technique
• Radio-frequency range, up to a few GHz
• Singel-layer coatings
• Multilayered coatings
• Sandwich structures
37
38
State of the art in shielding coatings
Metallization of plastic and composite
substrates
• PVC
: polyvinyl chloride
• GFRP : Glass Fiber Reinforced Plastic
9 layers of glass fiber tissue embedded in
epoxy resin
• CFRP : Carbon Fiber Reinforced Plastic
6 layers of carbon fiber tissue embedded in
epoxy resin
39
Technique
%
Target
Electroplating
40
Cu
Cu-Ni
>25
2-4 + 0.3
90-110
80-100
Conductive paint
50
Cu-Ag
Ni-Ag
Ag
18-37
5-25
5-17
60-75
75-85
80-90
Vacuum
metallization
5
Al
5-10
60-80
Others
5
Key-issues:
•
•
•
•
•
electrical conductivity
packing factor
adhesion
resistance to abrasion
resistance to corrosion and
oxidation
• costs
Thickness [µm]
SE [dB]
Limitation of existing techinques:
Electroplating:
• waste disposal
• only metallic material
Conductive paint:
• high porosity (use of Ag)
• difficulties in process control
40
The D.I.B.S. system at ENEA
Research Center “La Casaccia”
Rome, Italy
Dual Ion Beam Sputtering
(D.I.B.S.)
60 turns/min
substrate
+
Ar + O2
target
ion
source
Ar
+
substrate
ion
source
GUN2:
etching
(1 min)
GUN1:
sputtering
targets
pumping
system
p ≈ 10-4 mbar
41
42
Experimental Tests
Advantages:
SE measurement: standard set-up ASTM 4935/89
• Relatively low temperature (T < 50°C)
Ö suitable for plastic and composite
substrates
•
•
•
•
•
•
•
High control (thickness, masking)
Low porosity
Good uniformity
Multilayer coatings
Thin films
Both metallic and non-metallic target materials
Environmentally clean
43
• Frequency range : 30 kHz - 1 GHz
• 50 Ω - TEM coaxial waveguide
• External-shell diameter : 84 mm
44
Adhesion test: MIL-A-A113
Oxidation test: ISO 9022-2
• to apply the certified scotch
• to check the film detachment
• exposition of the sample to damp environment (T = 55°C,
90% - 95% of relative humidity)
• two cycles of 3 hours
Abrasion test:
MIL-CCC-C-440
• certified pumice rubber
abrader equipped with a
motorized linear slide
• 20 strokes over the
coating surface with the
rubber tip loaded up to
2½ pounds
45
Optimum design process
single-layer
film
simulation
film no.1
film no.2
substrate
Substrate :
optimization
abrasion
thickness
[µm]
oxidation
SE measurement
NO
YES
Nichel
0.46
Thickness
distribution along
the sample axis
?
END OF PROCESS
8.1 cm
8.4 cm
SE measurement
adhesion
3.5 cm
• Copper (Cu)
• Nickel (Ni)
DIBS deposition
multilayered
film
Single-Layer Coatings
Target material :
film
substrate
46
0.44
dmax= 0.46 µm
0.42
d = 0.42 µm
0.40
dmin= 0.38 µm
0.38
47
0
10
20
30
40
50
60
distance from the sample edge [mm]
70
48
80
GFRP substrate
R=d/t
d : film thickness
t : deposition time
growth rate
[nm/s]
tCu = 37 min
RCu = 2.04 ⋅10-4 µm/s
copper
Copper
0.20
Experimental
results
70 dB
d = 0.42 µm
GFRP / Ni (d)
40
20
0.16
0
Target
material
0.10
30
40
50
60
70
Sensitivity to film
thickness
80
Experimental results
49
Target
material
thickness
[µm]
tNi
[min]
Nickel
2d = 0.84
d = 0.42
d/2 = 0.21
120
60
30
PVC/Ni(d)
PVC/Ni(d/2)
80 dB80
40
1.45e7
0.7
0.42
58
Cu
5.8e7
0.7
0.42
68.5
600
variation of : ±6dB
900
50
( )
GFRP/Ni(d)/abrasione
80
7080 dB
GFRP / Ni (d)
40
GFRP / Cu (d)
60
40
GFRP / Cu (d)_abr.
20
20
300
600
900
1 GHz
0
300
600
frequenza [MHz]
[MHz]
frequency
900
1 GHz
• Nickel: SE reduction of about 4dB (from 30 kHz to 1 GHz)
1 GHz
SEdB = SEdB1(σ,µ,f) + SEdB2(σ,d)
SEdB2(σ,d) = 20 log10(σ d)
SE
[dB]
Abrasion test
frequenza [MHz]
frequency
[MHz]
frequenza [MHz]
[MHz]
frequency
1000
1 GHz
Ni
0
300
thickness
[µm]
GFRP / Ni (d)_abr.
20
800
packing
density
60
GFRP / Ni (2d)
GFRP / Ni (d)
GFRP / Ni (d/2)
60
600
conductivity
[S/m]
SE [dB]
20
distance from the sample edge [mm]
SE [dB]
10
400
frequenza [MHz]
frequency
[MHz]
Numerical results
0.12
0
200
30 kHz
tNi = 60 min
RNi = 1.28 ⋅10-4 µm/s
Nickel
nickel
0.14
SE [dB]
GFRP / Cu (d)
60
0.18
0
GFRP/Cu(d)
GFRP/Ni(d)
80
SE [dB]
Growth rate of the film
51
• Copper: SE reduction of 5dB-15dB (from 30 kHz to 1 GHz)
• for f > 500 MHz : SENi > SECu
52
Oxidation test
GFRP / Ni (2d)
GFRP / Ni (2d)_1st cycle
PVC/Ni(2d)/1
invecchiamento(3h)
GFRP
/ Ni (2d)_2nd cycle
90 dB
80
PVC/Ni(2d)/2° invecchiamento(6h)
SE [dB]
90 dB90
SE [dB]
CFRP / Cu (d)
60
30
60
40
0
0
300
600
900
frequenza[MHz]
[MHz]
frequency
20
1 GHz
The SE of the Ni-film is not affected by oxidation,
because Ni is a “passive” metal
0
300
600
Conclusions on single-layer coatings
6dB SE reduction after 3h-cycle
-
54
15dB SE reduction after 6h-cycle
( )
PVC/Ni(d)
80 dB80
y Cu-growth rate ≅ 2 Ni-growth rate
GFRP / Cu (d) / Ni (d)
GFRP / Cu (d)
GFRP / Ni (d)
60
SE [dB]
y Cu-resistance to abrasion and oxidation <<
Ni- resistance to abrasion and oxidation
Objective
substrate
20
110 dB
100
SE [dB]
40
Alluminio
120
film no.1
film no.2
1 GHz
Multilayer coatings - GFRP substrate
SECu> SENi
Multilayered coatings
900
frequenza[MHz]
[MHz]
frequency
The SE of the Cu-film is strongly affected by oxidation
53
y σCu ≅ 4 σNi
CFRP/Cu(d) CFRP / Cu (d)_1st cycle
CFRP/Cu(d)/1° invecchiamento(3h)nd
CFRP / Cu (d)_2 cycle
CFRP/Cu(d)/2° invecchiamento(6h)
0
400
600
frequenza [MHz]
frequency
[MHz]
800
1000
1 GHz
55
900
1 GHz
Cu (d) : 37 min
Ni (d) : 60 min
Cu (d) / Ni (d) : (37+60) min = 97 min
56
N.B. : It is not required to open the vacuum cell to change the target material
Deposition time:
40
200
600
frequency [MHz]
60
0
300
frequenza [MHz]
0.5 mm-thick
aluminum plate
80
Multilayer coatings - CFRP substrate
100
100 dB
• Minimum Ni-film thickness to assure satisfactory
mechanical properties and to speed up the deposition
process
CFRP/Cu(d)/Ni(d)
PVC/Cu(d)/Ni(d)
80
SE [dB]
Multilayer coatings - Optimization
CFRP / Cu (d) / Ni (d)
GFRP / Cu (d) / Ni (d)
• Maximum SE with fixed deposition time of about 100
min.
60
Numerical predictions:
40
tCu[min] tNi[min] tTOT [min] dCu[µm]
20
0
300
600
900
frequenza [MHz]
[MHz]
frequency
1 GHz
85
12
97
88
14
102
dNi [µm] SEc [dB]
0.97
0.088
77.5
1.0
0.1
77.7
57
Multilayer coatings - Optimization
Conclusions on multilayer coatings
CFRP substrate
CFRP / Cu
120
110 dB
58
CFRP/Cu/Ni.ott
(opt)CFRP/Cu(d)/Ni(d)
/ Ni (opt)
• Ni-film thickness of 0.1 µm assure
satisfactory mechanical properties
• Total required deposition time of 102 min
100
Alluminio
110 dB
CFRP/Cu/Ni.ott 100/90 dB
0.5 mm-thick Al plate
120
120 dB
CFRP / Cu (d) / Ni (d)
60
SE [dB]
SE [dB]
140
80
40
10 dB
20 dB
100
15 dB
90 dB
20
0
300
600
frequenza [MHz]
frequency
[MHz]
900
1 GHz
1 GHz
80
CFRP / Cu (opt) / Ni (opt)
0
The optimized coating passed successfully the adhesion-abrasion59
oxidation tests
300
600
frequenza [MHz]
frequency
[MHz]
900
1 GHz
60
Sandwich structures (PVC substrate)
INNOVATIVE LIGHTWEIGHT SHIELDS
TO REDUCE THE RADIATED
EMISSIONS FROM PCBs
120
90
• The new shield: materials and realization process
60
• Mechanical properties and geometrical characteristics
30
30 kHz
• EM shielding effectiveness measurements:
1 GHz
• ASTM 4935D tests
• tests in anechoic chamber
Ni 0.42 µm - PVC 3 mm - Ni 0.42 µm
Cu 0.42 µm - PVC 3 mm - Ni 0.42 µm
Ni 0.42 µm - PVC 3 mm
61
62
The New Shield Concept
Realization of the shield
Applications:
polycarbonate
125 µm
nickel 50 nm
sputtering
•mobile telecommunications
•automotive electronics
•medical systems
tin 5 µm
electroplating
Characteristics:
Planar Foil
Thermoforming
Process
• lightweight
• high level shielding effectiveness
3D-Formed
Shield of Any
Shape
• easy to assemble and remove
• different bonding systems available
• thermo-formable in any shape
63
64
Materials and Metallization Process
Sputtering:
Electroplating:
√ non-conducting substrate
√ fast
⊗ long deposition time
⊗ require conductive substrate
The Thermoforming Process
heating source [T1]
tin
planar
foil
Polycarbonate:
polycarbonate
√ good thermoformability
√ no degradation by ultraviolet radiations, chemicals and heat
Tin:
Nickel:
√ high ductility
√ good mechanical and
chemical properties
√ good thermoformability
√ good resistivity against
corrosion
heated metal plate [T2]
shape of the
shielding box
vacuum
√ conductive substrate
for tin coating deposition
• temperature: T1,T2 ≅ 200°C
• maximum elongation ≅ 200%
√ not toxic
65
Effect of thermoforming on shield thickness
The tin-layer thickness distribution is no more uniform after the
thermoforming
66
Effect of thermoforming on shield thickness
Profile of the tin-layer thickness of a thermoformed shielding box
[measurement method based on x-ray fluorescence]
Methods used for measurement of the tin-layer thickness:
• optical evaluation of samples by microscope
[mm]
• measurements of the weight of samples
• X-Ray fluorescence
Average thickness distribution of tin layer:
• corners
• edges
T ≅ 2 ÷ 3 µm
T ≅ 2.5 ÷ 3.5 µm
• side faces
T ≅ 3 ÷ 5 µm
• top face
T ≅ 4 ÷ 5 µm
67
[mm]
[mm]
[mm]
68
Effect of Aging on Shield Material
Adhesion Test
• Evaluation of degradation of performances due to aging
“Tape Test”:
• Samples are kept for 96 hours at 80ºC, 90% humidity
• a certified adhesive tape is applied on the tin layer of the
shielding foils
• DC resistance is measured before and after the test
production
lot
A
B
C
D
before
aging test
R [mΩ]
24.70
26.95
26.09
25.60
after
aging test
R [mΩ]
25.18
26.92
26.44
26.25
variation
of R
[%]
1.96
-0.12
1.36
2.54
• the tape is removed
variation of R
samples not subj.
to test [%]
1.78
0.76
2.92
• the test is passed if no residual of tin is deposited on the
removed tape
9 The effect of aging on material is negligible
9 All samples tested passed the test
69
SE Measurements
70
SE Measurements
Coaxial Waveguide
Coaxial Waveguide
Scheme of the test set-up
Test standard ASTM 4935D:
Electrical Engineering Department - University of Rome “La Sapienza”
√ widely used
Network Analyzer
√ high accuracy and reproducibility
HP 8753E
Sample
Holder
load
sample
√ limited external influences
87 mm
n
E
34 mm
H
⊗ only planar samples
Sample
⊗ limited frequency range: ~ 30 MHz - 1.5 GHz
Coaxial
Cables
71
5 mm
reference
sample
72
SE Measurements
Coaxial Waveguide
Results - Measured values of Shielding Effectiveness
SE Calculation
Shielding Calculation – Three Layer Structure
E0
H0
Ed
n
Hd
H0
n
1 2 3
Tin Nickel
E0
Hd
Φ1
Φ2
Φ3
Ed
Transmission matrix:
Polycarb.
[Φ ] = [Φ1 ][Φ 2 ][Φ 3 ]
 Ed  Φ11 Φ12   E0 
 H  = Φ
 
 d   21 Φ22   H 0 
73
74
SE Calculation
SE Calculation
Comparison between measured and computed data
Comparison between measured and computed data
Physical parameters of the
three-layer shield used for
the SE calculation
∆ [µ m ] σ [ S/m] ε r µ r
3 ; 5 ; 7 8 ⋅ 106 1 1
tin
0.05 1.5 ⋅ 107 1 1
nickel
125
polycarb.
~ 10-14 2.9 1
Comparison between the
measured and the calculated
SE level, using the three-layer
model
[average value in frequency
range 30 MHz - 1.5 GHz]
Measured and
Calculated SE,
in the case
∆TIN = 5 µm
∆ TIN Measured Calculated
SE [dB]
[µ m] SE [dB]
3
72.48
73.40
5
78.92
77.81
7
80.35
80.94
75
76
SE Calculation
SE Calculation
Approximation of One Layer Structure
Approximation of One Layer Structure
• σpolycarb =
10-14
S/m ⇒ Polycarbonate layer is neglegible
freq
[MHZ]
100
1000
1500
• dnickel = 50 nm ⇒ Nickel layer is neglegible
ONE LAYER MODEL (ONLY TIN CONSIDERED)
SEdB = AdB + RdB + BdB
AdB = 20 ⋅ log10 eγ ⋅d
3 µm
73.11
73.12
73.14
SE [dB]
R [dB]
5 µm 7 µm
77.55 80.48 79.54
77.67 80.90 69.54
77.81 81.41 67.78
3 µm
1.46
4.63
5.67
A [dB]
5 µm 7 µm
2.44 3.42
7.72 10.80
9.45 13.23
3 µm
-7.89
-1.05
-0.31
B [dB]
5 µm 7 µm
-4.43 -2.48
0.41 0.56
0.58 0.40
absorption
(η0 + η )
2
RdB = 20 ⋅ log10
reflection
4 ⋅η 0 ⋅η
2
 η − η  − 2⋅γ ⋅d
 ⋅ e
BdB = 20 ⋅ log10 1 −  0
 η0 + η 
reflection is the dominant component of the SE
multiple
reflection
77
Shielding Measurements
Anechoic Room
78
Shielding Measurements
Anechoic Room
Scheme of test set-up
√ wide frequency range
EMC Lab - NLR (National Dutch Aerospace Laboratories)
√ 3D samples
Emitting Antenna
√ study of the influence of
the bonding system on SE
1.2 m
1m
Horn Antenna
Emitting
Antenna
Sample
Under Test
Receiving
Antenna
SE ⇒ comparison of the
received signals:
• open aperture
IN
⊗ reflection
OUT
1.6 m
⊗ resonances
⊗ limited dynamic range
Far Field
Configuration
⊗ influence of source
OUT
• sample occluding the aperture
79
IN
80
Shielding Measurements
Anechoic Room
Scheme of test set-up
Shielding Measurements
Anechoic Room
Connection Systems - Flat
EMC Lab - NLR (National Dutch Aerospace Laboratories)
Emitting Antenna
1m
Printed Loop
Antenna
(Magnetic Dipole)
IN
OUT
IN
REFL
FORW
OUT
Near Field
Configuration
OUT
shielding
box
plastic frame
that presses
the shield to
PCB
PCB
IN
Simple
Wide Contact Area
Need of an External Pressing Tool
Strong Pressure Required
81
Shielding Measurements
Anechoic Room
Connection Systems - Embossing
82
Shielding Measurements
Anechoic Room
Connection Systems - Glue
shielding
box
shielding
box
contact
area
plastic frame
that presses
the shield to
PCB
PCB
glue
Narrow Border Width (>0.8 mm)
PCB
Low Pressure Required Due to the
“Spring Effect” of the Embossed Shape
Need of an External Pressing Tool
83
No External Pressing Tool Required
Need of Glue
Complex Border Shape
84
Shielding Measurements
Anechoic Room
Results - Far Field - Frequency Range 1÷2 GHz
Shielding Measurements
Anechoic Room
Results - Near Field - Frequency Range 1÷2 GHz
Average SE [dB] :
Average SE [dB] :
Flat
Embossing
Glue
Flat
Embossing
Glue
67.6
67.1
62.9
Boxes Tested :
Flat
Embossing
Glue
Boxes Tested :
23
5
3
Flat
Embossing
Glue
85
Shielding Measurements
63.8
66.4
54.8
9
3
3
86
Anechoic Room
Results - Far Field - After Induced Aging
Shielding Measurements
Anechoic Room
Results - Far Field - Frequency Range 2÷4 GHz
Average SE [dB] :
Average SE [dB] :
Flat
Embossing
Flat
Embossing
65.3
65.9
Boxes Tested :
Flat
Embossing
87
73.8
75.4
Boxes Tested :
3
18
Flat
Embossing
88
5
9