Communications, Computer & Consumer Electronics Business Unit
AXICOMAXICOM
The Design Challenges Involved in Miniaturization of Electromechanical
Relays
Dr. Werner Johler
Tyco Electronics AXICOM
Switzerland
52nd IEEE Holm Conference on Electrical Contacts
2CC&CE
AXICOM RelaysAXICOM Relays
Characteristics Telecom / Signal Relays
•Low contact resistance [m ]
and high insulation
resistance [M ]
•High insulation > 2500V
– Between open contacts
– Between load and control
circuit
•Switching range from µV to
250V and nA to 5A
•Resistant against
electromagn. interference
•Robust against
– over-current
– over-voltage
– over-temperature
•Reliable even in harsh
environment
•Linear characteristic
•Good RF characteristics
•Easy to use
•Cost effective
3CC&CE
AXICOM RelaysAXICOM Relays
Overview
I Introduction
II Miniaturization
III Relay Protection
IV Contact Reliability in Miniaturized Relays
V Isolation, Dielectric and Surge Characteristics
VI Thermal Limitations
VII Alternatives to Electromechanical Relays
VIII Conclusions
4CC&CE
AXICOM RelaysAXICOM Relays
Challenges to Relays in Electronic Circuits
•extremely low loads with
– voltages - µV, but also 1500 Vrms
– currents – nA, but also 500 A
• load and monitoring circuits in parallel in the same
switching devices
• load and monitoring circuits in sequence during the
lifetime of the relay
•high and low temperature exposure
•higher reliability and increased safety requirements
•zero defect expectation
5CC&CE
AXICOM RelaysAXICOM Relays
Relay - Requirements
control unit / magnet system contact side / contact system
relay
mechanical resistance(shock, vibration,..) processing
(solderbilityt, terminal planarity, ..)
contact load(current/voltage)
life time(electrical/machanical)
enviroment(climate,gas,detergent..)
temperatureisolation system(dielectric strength,isolation resistance)
Volume, PCB-space-(lxhxw)
sound emission
power supplier
cost/price
tim e
contact resistance
6CC&CE
AXICOM RelaysAXICOM Relays
Miniaturization of Telecom Relays
339
1050
2200
7133
60
112.5
200
457
100
30
10
5
1
10
100
1000
10000
1G - 1965 2G -1980 3G - 1990 4G - 1999 5G
Vo
lum
e [m
m3]
1
10
100
1000
Bo
ard
spac
e [m
m2
] /
To
lera
nce
[µ
m
Volume [mm3] Boardspace [mm2] Tolerance [µm]
?
7CC&CE
AXICOM RelaysAXICOM Relays
Key Characteristics
140140150Coil power [mW]
13011085Thermal res. [K/W]
3/35/57/6Op./rel. time [ms]
2500
1500
2500
1500
1500
1500
Surge Coil– contacts
Contacts
223Max .cont. current [A]
220/250220/250220/250Max. cont. voltage [V]
60 / 62.560 / 62.560 / 62.5Load power [W/VA]
1.5 - 242 – 483 – 48Coil voltage [V]
10 x 6 x 5.6515 x 7.5 x 1020 x 10 x 11Dimensions [mm]
4th Generation3rd Generation2nd Generation
8CC&CE
AXICOM RelaysAXICOM Relays
Relay - Elements
Housing - Protection
Actuator – Magnetic circuit
Spring set – Contact system
9CC&CE
AXICOM RelaysAXICOM Relays
Actuator
•small in size
•low-power consumption
•high-force and high-displacement
•similar characteristics than springs
•ability to store energy for bistable (latching)
switching characteristic
•highly efficient
•high-speed of operation
10CC&CE
AXICOM RelaysAXICOM Relays
Actuator Principles
Linear force-displacement-characteristic
Force
Powerdissipation
Conclusion Coil heating Small displacement
Electromagnetic
Actuator
Electro-
static
Piezo-
electric
F
d
F
d
F
d
Thermal
F
d
F k d U c d* * *31F k I c d* *2
P I~ 2P V~ /1 0 0
F ANI
d0
2
2* * F A
V
d0
2
2* *
11CC&CE
AXICOM RelaysAXICOM Relays
Non polarized Magnetic circuitp
0
4
8
12
16
20
24
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Armature travel (mm)
Sp
rin
g s
et-
arm
atu
re-
forc
e (
cN
)
operate V
release V
12CC&CE
AXICOM RelaysAXICOM Relays
Polarized Magnetic Circuit
Armature
Permanent Magnet
Coil
YokeS
N
13CC&CE
AXICOM RelaysAXICOM Relays
Polarized Magnetic Circuit
Armature
Permanent Magnet
Coil
Yoke
SN
S
14CC&CE
AXICOM RelaysAXICOM Relays
Polarized Relay
-16
-12
-8
-4
0
4
8
12
0 50 100 150 200 250
Armature travel (my)
Arm
atur
e fo
rce
(cN)
0 V
release V
nom V operate V
contact set
15CC&CE
AXICOM RelaysAXICOM Relays
Coil Arrangement
Standard Coil Flat Coil
16CC&CE
AXICOM RelaysAXICOM Relays
Spring set – Contact system
• large contact distance and high insulation resistance in the
open condition
•high contact force and low contact resistance in the closed
condition
•optimum relative movement during contact closing
•high contact opening force
•minimum contact bouncing during contact closing and
opening
•provide the necessary insulation between open contacts,
between adjacent contacts and between coil and contacts
•high resistance against mechanical shock and vibration
17CC&CE
AXICOM RelaysAXICOM Relays
Contact Gap
Sensitivity
Initial End of Life
Dielectric & Surge
Size of Relay
19CC&CE
AXICOM RelaysAXICOM Relays
Plastics
PBT
PPO
PPS
PEK
LCP
PAI
PET
PP
PA6/66
PE-LD
PI
PC
PMMA
SANPVC
PS
High Performance
(HDT > 150°C)
Technical Polymers
(HDT = 100 - 150°C)
Commodities
Pri
ce
/ P
erf
orm
an
ce
amorphous semicrystalline
PEIPES
PPAPSU
SAN ABS
PA 46PAR
Plastics Pyramide
PE-HD
FP
PE UHMW
LFT
POM
COC
20CC&CE
AXICOM RelaysAXICOM Relays
Copper Materials
200 300 400 500 600 700 800 900 1.000
Ele
ctr
icalco
nd
ucti
vit
y(M
S/m
)
Ele
ctr
ica
lc
on
du
cti
vit
y(%
IA
CS
)
Rp0,2 (MPa)
0
10
20
30
40
50
10
20
30
40
50
60
70
80
90
100
0
1.100 1.200
CuZn15 M15
CuSn0,15 K81CuCrAgFeTiSi K88
CuCrSiTi K75
CuFe2P K65
E-Cu K32SE-Cu K14
CuNi18Zn20 N18CuNi9Sn3 L49
CuNi3SiMg K55
CuSn3Zn9 S12
CuZn30 M30
CuSn4 B14CuZn23Al3Co S23
CuSn8 B18
CuNiSi C19010
K57
CuNi1SnP C19025
CuBe2 C172
CuTi3 C199
Edelstahl X12CrNi177
21CC&CE
AXICOM RelaysAXICOM Relays
Permanent Magnets
Year
En
erg
y D
en
sit
y
Ferrite
steel
22CC&CE
AXICOM RelaysAXICOM Relays
Contacts
Galvanically spot platted
contacts
Multilayer contact -
welded
0.35 mm
0.1
35
mm
Precious metal = 4 µm Precious metal = 55 µm
24CC&CE
AXICOM RelaysAXICOM Relays
Overview
I Introduction
II Miniaturization
III Relay Protection
IV Contact Reliability in Miniaturized Relays
V Isolation, Dielectric and Surge Characteristics
VI Thermal Limitations
VII Alternatives to Electromechanical Relays
VIII Conclusions
25CC&CE
AXICOM RelaysAXICOM Relays
Protection of Relays IEC 61810-7
• RT 0 unenclosed: not provided with a protective case
• RT I dust protected: provided with a case which protects its
mechanism from dust
• RT II flux proof: A relay capable of being automatically soldered with
no migration of solder fluxes beyond the intended areas.
• RT III: wash tight: A relay capable of being automatically soldered and
subsequently undergoing a washing process to remove flux residues
without allowing the ingress of flux or washing solvents
• RT IV sealed: A relay provided with a case which has no venting to the
outside atmosphere and having a time constant better than
2 x 104 s.
• RT V: hermetically sealed: A sealed relay having an enhanced level of
sealing assuring a time constant better than 2 x 106s.
26CC&CE
AXICOM RelaysAXICOM Relays
Contamination
•Sealed housings protect relays from external
contamination but
•Internal contamination
–Particles
–Oil and grease from production
–Silicon
–Outgassing products from insulating materials
27CC&CE
AXICOM RelaysAXICOM Relays
Particles – Critical Size
contact
contact
particle
0 10 20 30 40 50 60
contact force [cN]
0
2
4
6
8
10
12
14
part
icle
siz
e[u
m]
28CC&CE
AXICOM RelaysAXICOM Relays
Impact Ambient Temperature
CH02.167
Konta
ktw
iders
tan
d[O
hm
]
1000 Schaltungen
0 85 170 255 340 425
-3 10
-2 10
-1 10
0 10
1 10
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
0
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
Number of operations [thousands]
Conta
ct R
esi
stance
[O
hm
]
CH02.167
Konta
ktw
iders
tan
d[O
hm
]
1000 Schaltungen
0 85 170 255 340 425
-3 10
-2 10
-1 10
0 10
1 10
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
0
Leer
150
C
Pro
be
Raum
80
C
100
C
120
C
150
C
Number of operations [thousands]
Conta
ct R
esi
stance
[O
hm
]
29CC&CE
AXICOM RelaysAXICOM Relays
Outgassing of Insulating Materials
initial
Magnetic wire
optimized initial
Plastics
optimized0
200
400
600
800
1000
ou
tga
ssin
gra
t e[p
pm
]
120°C 200°C 250°C
30CC&CE
AXICOM RelaysAXICOM Relays
Gastight/Hermetically Plastic Sealed Relays
•Lifetime of 25 years must be met
•50% of the initial filling at the end of life
•Survival of 3 times SMD soldering processes –
peak temperature 260°C
31CC&CE
AXICOM RelaysAXICOM Relays
Gas Penetration Plastics
A B C D E
plastic material
0
20
40
60
80
100
120
ga
sp
erm
ea
bil
ity
(a
rbit
rary
un
its
)
N SF 2 6
32CC&CE
AXICOM RelaysAXICOM Relays
SF6 Partial Pressure
0 100 200 300 400 500
time ( years )
0
10
20
30
40
50
60
70
80
90
100
SF
-p
art
i alp
res
su
r e(
kP
a)
6
25
93
35CC&CE
AXICOM RelaysAXICOM Relays
Integrity of Plastic Housings
• Stress during soldering
– SMD soldering process
• Stress during relay life
– Thermal endurance
– Damp heat
– Rapid change of temperature
– Pressure storage
– Temperature cycle IEC60950
– Climatic sequence
initial final c-c no nc0
20
40
60
80
100
conta
c tre
sis t
anc e
(m
Ohm
)
1
2
3
4
5
die
l ect
r ic
withst
and
voltage
(kV
)
0
p
Rapid change of temperature
36CC&CE
AXICOM RelaysAXICOM Relays
SMD Soldering – Lead Free Process
0 50 100 150 200 250 300 350 400 450 5000
50
100
150
200
250
300
tem
per a
tur e
[°C
]
37CC&CE
AXICOM RelaysAXICOM Relays
Pressure = f(temperature)
Theory
Reality
Humidity
Outgassing products
plastics
magnetic wire
resin
Additional pressureincrease
pressure
sensor
oven
DUT
..
constT
Vp
38CC&CE
AXICOM RelaysAXICOM Relays
0 50 100 150 200 250 300 350
temperature [°C]
0,5
1
1,5
2
2,5
3
3,5
4
pr e
ssu
r e[ b
ar]
theory
poormaterialsand/ormoisture
theoryoptimizedmaterialsand dry components
Pressure = f (temperature)Optimized Situation
Outgassing products- Pressure increaseMoisture- Pressure increase
39CC&CE
AXICOM RelaysAXICOM Relays
Water vapor transmission of plastics
Oxygen Permeability [cm3 mm/m2 day bar]
Water Vapor Transmission Rate [g mm /m2 day]
��
��
��
��
��
��
0,001 0,01 0,1 1 10 1000,001
0,01
0,1
1
10
100
LCP
HDPE
PCTFE
PET
Nylon 6
PVDC
40CC&CE
AXICOM RelaysAXICOM Relays
Impact Humidity
��
��
� � ��
0 200 260 440
time in [s]
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
inte
rna
l pre
ssu
re in
cre
ase
[mb
ar]
Manufa
ct.
14d@
23°C
-50%
r.h.
Dry
pack
14d@
55°C
-95%
r.h.
14d
@55°C
- 95%
r.H
.
ESD
bag
14d
@55°C
- 95%
r .H
.
��
��
� � ��
0 200 260 440
time in [s]
40
60
80
100
120
140
160
180
200
220
240
260
280
t em
pe
rat u
rein
[°C
]
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
inte
rna
l pre
ssu
re in
cre
ase
[mb
ar]Initial
43CC&CE
AXICOM RelaysAXICOM Relays
Overview
I Introduction
II Miniaturization
III Relay Protection
IV Contact Reliability in Miniaturized Relays
V Isolation, Dielectric and Surge Characteristics
VI Thermal Limitations
VII Alternatives to Electromechanical Relays
VIII Conclusions
44CC&CE
AXICOM RelaysAXICOM Relays
Contact Materials
•Gold - layer
– Au
– AuAg 8 ... 10
– AuNi 2 ... 5
– AuPd 2 ... 4
– AuCo 0.2 .... 0.5
•Contact - layer
– AgNi 10 ... 20
– AgPd 60
– PdRu 10
– W
– Ru
AgPd 60
Cu Ni 30 Fe
AuAg 8
0.3 mm
0.1
33
mm
Ag Ni 20
Cu Ni 30 Fe
AuNi 2
0.3 mm
0.1
4m
m
47CC&CE
AXICOM RelaysAXICOM Relays
Gold Based Contact Materials
•Deposition process
– Sputtered gold layers
– Rolled gold layers
– Electro deposited gold layers
Standard
Annealed
– Cleanness of Contacts
– Relay Manufacturing
48CC&CE
AXICOM RelaysAXICOM Relays
Welding Process – Resistive Welding
Cu electrode
Cu electrode
Base material
Contact
profile
50CC&CE
AXICOM RelaysAXICOM Relays
Low Contact Force
0 500 1000 1500 2000 2500
Number of operation [thousands]
0.01
0.1
1
10Contact circuit resistance [ohm]
Fc = 2 cN Ambient = Air
0 500 1000 1500 2000 2500
Number of operation [thousands]
0.01
0.1
1
10Contact circuit resistance [ohm]
Fc = 2 cN Ambient = SF6
51CC&CE
AXICOM RelaysAXICOM Relays
Material transfer
Dielectric and surge
Endurance Timing
Operate & Release
Sticking & Bridging
52CC&CE
AXICOM RelaysAXICOM Relays
Reqiurements for Switching Contacts in Telecom / Signal Relays
–Low and stable contact resistance
–High resistance against welding during
switching electrical load
–No or minimum material transfer/forming of pip
and crater during DC switching
–Low contact erosion
–Low contact material thickness
–Low cost
53CC&CE
AXICOM RelaysAXICOM Relays
Test Samples
•Hermetically sealed - plastic relay
– Defined switching atmosphere
N2
SF6
Any Mixtures of gases
– Time constant better 1011 s
– Lifetime > 25 years
– Pressure and characterisiticsnot depending on altitude
54CC&CE
AXICOM RelaysAXICOM Relays
Contact Material – Switching atmosphere
Cu
5µm W or Ru1.5 µm Au
0.35 mm
0.1
35
mm
W and Ru have a high tendency towards oxidation
Inert switching atmosphere required (N2, SF6 etc.)
1.5 µm Au
0.35 mm
CuNi 30
25 µm
0.35 mm
CuNi 30
55 µm AgNi 20
55CC&CE
AXICOM RelaysAXICOM Relays
•Contact loads
– 125 V/0.24 A - 30 W resistive
– 24 V / 1.25 A - 30 W resistive
– Cable load open end 10 m/48 V
– No load and CC0 test ( 30mV/ 10mA)
•Number of operations:
– 500 000 resistive loads
– 1 600 000 cable load
•Contact material / Atmosphere
– Ru + Au in 100% N2
– Ru + Au in 100% SF6
– W + Au in 100% N2
– W + Au in 100% SF6
Experimental Parameters – Telecom Relays
56CC&CE
AXICOM RelaysAXICOM Relays
0 100 200 300 400 500
number of operation [thousands]
0,01
0,1
1
10contact circuit resistance [ohm]
PdRu10 + Au in SF6- 125 V/0.24 A
0 100 200 300 400 500
number of operation [thousands]
0,01
0,1
1
10contact circuit resistance [ohm]
Ru + Au in N2- 125 V/0.24 A
0 100 200 300 400 500
number of operation [thousands]
0,01
0,1
1
10contact circuit resistance [ohm]
Ru + Au in SF6- 125 V/0.24 A
0 100 200 300 400 500
number of operation [thousands]
0,01
0,1
1
10contact circuit resistance [ohm]
W + Au in N2- 125 V/0.24 A
Electrical Endurance 125 V / 0.24 A
0 100 200 300 400 500
number of operation [thousands]
0.01
0.1
1
10contact circuit resistance [ohm]
W + Au in SF6- 125 V/0.24 A
AgNi20+Au-N2
AgPd+Au-N2
PdRu10+Au-N2
PdRu10+Au-30%SF6
PdRu10+Au-SF6
Ru+Au-SF6
Ru+Au-N2
W+Au-SF6
W+Au-N2
contact material and ambient gas
0,01
0,1
1
conta
c tre
sis t
anc e
[ Ohm
]
57CC&CE
AXICOM RelaysAXICOM Relays
AgNi 20 + Au
100%N2
Make and Break - 125V/0.24A - 30 W
AgPd 60 + Au
100%N2
PdRu 10 + Au
100% SF6
W + Au
100%N2
W + Au
100% SF6
W + Au
100% SF6
Ru + Au
100% N2
Ru + Au
100% SF6
Contact Erosion – 125V / 0.24V
58CC&CE
AXICOM RelaysAXICOM Relays
Material Transfer 125V/0.24A - 30 W
Make and Break AgNi 20 + Au in 100%N2
59CC&CE
AXICOM RelaysAXICOM Relays
Material Transfer 125 V/0.24 A
AXICOM Communication Relays
0
20
40
60
80
100
120
-20
-40
-60
-80
-100
-120
Ma
xim
um
de
pt h
of
ero
sio
n[u
m]
An
od
eC
ath
od
e
AgNi20+Au
100% N2
bre
ak
+
ma
ke
ma
ke
bre
ak
AgPd60+Au
100% N2
bre
ak+
ma
ke
ma
ke
bre
ak
PdRu10+Au
100% N2
bre
ak
+
ma
ke
ma
ke
bre
ak
PdRu10+Au
30% SF6
bre
ak
+
ma
ke
ma
ke
bre
ak
PdRu10+Au
100% SF6
bre
ak
+
ma
ke
ma
ke
bre
ak
bre
ak
+
ma
ke
ma
ke
+
bre
ak
Ru+Au
SF6 N2
bre
ak
+
ma
ke
ma
ke
+
bre
ak
Ru+Au
SF6 N2
60CC&CE
AXICOM RelaysAXICOM Relays
Sticking Contacts 125 V/0.25 A
NC
M&B
NC
Mak
e
NC
Bre
ak
NO
M&B
NO
Mak
e
NO
Bre
ak
0
20
40
60
80
100
sti
ck
ing
co
nta
ct s
[%]
W+Au-N2 W+Au-SF6 Ru+Au-N2
Ru+AuSF6 PdRu10+Au-100%SF6 PdRu10+Au-30%SF6
PdRu10+Au-100%N2 AgPd60+Au-100%N2 AgNi+Au-N2
64CC&CE
AXICOM RelaysAXICOM Relays
Overview
I Introduction
II Miniaturization
III Relay Protection
IV Contact Reliability in Miniaturized Relays
V Isolation, Dielectric and Surge Characteristics
VI Thermal Limitations
VII Alternatives to Electromechanical Relays
VIII Conclusions
65CC&CE
AXICOM RelaysAXICOM Relays
Isolation System Relay
•Coil to contacts
–Solid + gaseous
•Open contacts
–Gaseous
•Adjacent contacts
–Solid + gaseous
66CC&CE
AXICOM RelaysAXICOM Relays
Isolation
•Defined by
– Isolation resistance @ 500VDC
– Dielectric AC or DC
– Surge
– Clearance and creepage distances
•Depends on
– Distance
– Geometry
– Material / gas type
– Pressure
– Humidity
67CC&CE
AXICOM RelaysAXICOM Relays
Isolation, Dielectric and SurgeCharacteristics
•Telecom relays must be capeable to withstand
– 2500 V surge voltage (2 /10 µs)
– 1500 Vrms – 1 minute
– 500 A pulse current (8 /20 µs)
– Continuous current of 60A / 5s
69CC&CE
AXICOM RelaysAXICOM Relays
Dielectric and Surge
0,001 0,01 0,1 1 10 100 1000
pressure x electrode distance ( 100 kPa . mm )
0,1
1
10
100
1000
die
lec t
ric
withst
and
voltage
(kV
)
N2SF6
0,2
2,51,5
0,6
70CC&CE
AXICOM RelaysAXICOM Relays
Dielectric and Surge – 4G relay
nc1 nc2 no1 no2 c-c nc1 nc2 no1 no2 c-c0
1
2
3
4
5
die
lec
tric
wit
hsta
nd
vo
ltag
e(
kV
)
N2 SF6
71CC&CE
AXICOM RelaysAXICOM Relays
Isolation –Application
IEC 60950 IEC 60335-1 IEC 60730-1
EN 60950temperature cut-outs.
household and similar thermostats and
business equipment electrical applliances similar controls.
b + s b + s b + s
double insulation
contact- coil- contact- coil- contact- coil-
consisting side side side side side side
basic-insulation 1.5 kV 1.5kV 1.25 kV 2.5kV 2.0 kV 2.5kV
plus
supplementary
insulation min. 0.4mm min. 1mm min. 1mm
r r r
1.5kV 3.75kV 4.0kV
reinforced
insulation
min. 0.4mm min. 1mm min. 1mm
if no mechanical stress min. 2mm min. 2mm
b + s b + s b + s
basic-insulation
plus
1.5kV 2.5kV 2.5kV
supplementary 1.5 kV 1.25kV 2.0kV
insulation 1.5kV 2.5kV 2.5kV
with two layers
r r r
reinforced
insulation
3.0kV 3.75kV 4.0kV
with 3 layers
(or 2 layers)
3.0kV
reinforced insulation compromises three layers of insulation
material for which all combinations of two layers together
pass the electric strenght test for reinforced insulation.
creepage distances/
clearances between 5/4mm 8/8mm 8/6mm
contact and coil
The statet CTI-value
is valid for these IIIa / IIIb > 250 > 250
plastic parts which
bear terminals
IEC/EN 60950Business Equipment
IEC/EN 60335-1Household a. similar
IEC/EN 60730Temperature cut outs
72CC&CE
AXICOM RelaysAXICOM Relays
Isolation, Dielectric and SurgeCharacteristics
– The insulation of a gaseous isnulation can be increased by
Bigger gap
Higher pressure
Better insulating gas
– Gastight relay housings enable the use of better insulating gases such as SF6 which results
reduction of contact gap
increases the capability of the whole isolation system
73CC&CE
AXICOM RelaysAXICOM Relays
Overview
I Introduction
II Miniaturization
III Relay Protection
IV Contact Reliability in Miniaturized Relays
V Isolation, Dielectric and Surge Characteristics
VI Thermal Limitations
VII Alternatives to Electromechanical Relays
VIII Conclusions
74CC&CE
AXICOM RelaysAXICOM Relays
Thermal Limitations
•Relay parameters are temperature depending
•Thermal resistance is increasing with smaller
designs
•Relays are used in higher ambient temperature –
engine compartment
•Materials are suitable only for a certain
temperature range
•Safe operation required, even hot start
75CC&CE
AXICOM RelaysAXICOM Relays
2nd - 4th Generation - Miniaturization
Volume
Surface
Thermal
resistance
0
500
1000
1500
2000
2500
2G 3G 4GRelay Generation
Vo
lum
e [
mm
3]
/ S
urf
ace
[m
m2]
0
20
40
60
80
100
120
140
Th
erm
al
Re
sis
tan
ce
[K
/W
]
76CC&CE
AXICOM RelaysAXICOM Relays
Coil operating range – Physical Dimensions
Urel
Uop
2G max.125°C
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
Urel
Uop
3G max.125°C2G max.125°C
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
Urel
Uop
4G max.125°C
3G max.125°C2G max.125°C
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
Urel
Uop
4G max.150°C
4G max.125°C
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
77CC&CE
AXICOM RelaysAXICOM Relays
Operating Temperature Range – Coil Power
Urel
Uop
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
Urel
Uop
80mW - 0A
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
Urel
Uop
80mW - 0A
140mW -0A
200mW - 0A
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
78CC&CE
AXICOM RelaysAXICOM Relays
Operating Temperature Range – Current
Urel
Uop
140mW -0A
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
Urel
Uop
140mW -0A140mW-
2x1A
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
Urel
Uop
140mW -0A
140mW-
2x2A
140mW-
2x1A
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
2,2
2,4
2,6
2,8
3
3,2
3,4
-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Ambient Temperature [°C]
Co
il o
pe
rate
vo
lta
ge
[U
/U
N]
79CC&CE
AXICOM RelaysAXICOM Relays
Coil operating range – Latching Relays
Non latch
100mW
Non latch
200mW0
1
2
3
4
5
6
7
8
9
10
11
12
13
-60 -40 -20 0 20 40 60 80 100 120 140
Ambient Temperature [°C]
Co
il v
olt
ag
e [
U/U
N]
Non latch
100mW
Latching
100mW-5%
Non latch
200mW
Latching
200mW-5%
0
1
2
3
4
5
6
7
8
9
10
11
12
13
-60 -40 -20 0 20 40 60 80 100 120 140
Ambient Temperature [°C]
Co
il v
olt
ag
e [
U/U
N]
Non latch
100mW
Latching
100mW-5%
Non latch
200mW
Latching
200mW-5%
Limiting
voltage
0
1
2
3
4
5
6
7
8
9
10
11
12
13
-60 -40 -20 0 20 40 60 80 100 120 140
Ambient Temperature [°C]
Co
il v
olt
ag
e [
U/U
N]
80CC&CE
AXICOM RelaysAXICOM Relays
Thermal Limitations – Telecom / Signal Relays
•Smaller deisgns have a higher thermal resistance
and a smaller area of safe operation
•Self heating of the coil results in considerable
temperature increase
•Higher current has the major contribution to the
self heating
•Better materials allow an increase of the maximum
permitted relay temperature
•At high ambient temperatures the use of latching
relays is strongly recommended
81CC&CE
AXICOM RelaysAXICOM Relays
Overview
I Introduction
II Miniaturization
III Relay Protection
IV Contact Reliability in Miniaturized Relays
V Isolation, Dielectric and Surge Characteristics
VI Thermal Limitations
VII Alternatives to Electromechanical Relays
VIII Conclusions
82CC&CE
AXICOM RelaysAXICOM Relays
Comparison - AlternativesElectro-
mechanicalTelecom/
Signal Relay
MEMSRelay(SiR)
ReedRelay
Transis-tor
SolidStateRelay(SSR)
Opto-coupler
On Resistance very low medium low high high high
Off Resistance very high very high very high low low high
Galvanic separationcontrol – loadload circuit
yesyes
yesyes
yesyes
nono
yesno
yesno
Leakage current no no no yes yes yes
Dielectric/Surge very high medium medium low high high
DC switching yes yes yes yes yes yes
AC switching yes yes yes no yes no
Linearity yes yes yes no no no
Resistance tooverload
very high average average low low low
Resistance toexcess temperature
very high high high low low low
Resistance to EMI high average high low low low
Control power medium very low medium very low medium low
Board-space medium low medium very low high low
Switching frequency medium medium medium very high low very high
Noise, electromagn. medium low medium very low very low very low
Noise, acoustic high low medium low low low
Endurance medium high medium very high very high very high
Cost medium medium high very low high low
83CC&CE
AXICOM RelaysAXICOM Relays
Overview
I Introduction
II Miniaturization
III Relay Protection
IV Contact Reliability in Miniaturized Relays
V Isolation, Dielectric and Surge Characteristics
VI Thermal Limitations
VII Alternatives to Electromechanical Relays
VIII Conclusions
84CC&CE
AXICOM RelaysAXICOM Relays
Development of Relay Technology
•Smaller size – better performance enabled by
– FEM (Finite Element Method)
– maximum efficiency permanent magnets
– efficient magnetic circuits based on the see-saw principle
– flat coil technology for miniaturized design
– overmoulded coils and ENG (Electro-Negative Gases)
technology
– miniaturized multilayer contacts with sputtered gold surfaces
– low outgassing and high-temperature insulation materials
85CC&CE
AXICOM RelaysAXICOM Relays
Innovations Telecom/Signal Relays
•Miniaturization is driving relay innovations
•Miniaturization results in
–Reduced contact forces
–Reduced contact break forces
–Reduced over travel
•Miniaturized relays capable to provide
–Unchanged switching characteristic
86CC&CE
AXICOM RelaysAXICOM Relays
Innovations Telecom/Signal Relays
•Gas tight plastic sealed housings enables
–use of inert and higher insulating gases
–higher insulating gases e.g. SF6 enablesreduction of dielectric distances
•Minimizing the contact erosion allows
–reduce the initial contact gap
–Enable the use of best combination of contact material and ambient gas
–further reduction of the size of electromechanical relays