Confidential
Reliability
of
Spring Contacts





Basics of electrical spring contacts
Micro-vibration
Temperature cycling
Industrial atmosphere
Shock & Vibration
1
Confidential
Customer Concerns
Advantages
General Considerations
Spring Contact
Solder Contact (PIN)
Comments
Utilization of PCB area
+
o
No through-holes
Connection of power module to
PCB
++
-
No alignment and
tolerance problems
Equipment investment for
inverter production
++
-
No solder line
needed
Inverter assembly time and cost
++
o
Easy mounting
Rework and field service
+
o
Contact resistance
o
++
Contact stability in temperature
cycling
+
o
Contact stability in industrial
environment
+
+
Contact stability under shock
and vibration
+
o
++
+
o
-
Excellent
Good
Adequate
Bad
No fatigue of solder
contacts (cold
joints)
No fractures as in
solder contacts
Comparison Spring contact / Solder contact
2
Qualification Standards – SEMiX™
Confidential
Test
Test Conditions
Standard
High Temperature Reverse Bias
IGBT 600/1200 V
1700 V
1000h, VGE = 0V
95% VDSmax / VCEmax,
Tc = 140°C
Tc = 125°C
IEC 60747
High Temperature
Gate Stress
High Humidity
High Temperature
Reverse Bias
1000h,  VGSmax / VGEmax,
Tvjmax
1000h , 85°C, 85% RH
VDS/VCE= 80% VDSmax/VCEmax,
max. 80V, VGE = 0V
04
High Temperature Storage
1000h, T = + 125°C
IEC 60068 Part 2-2
05
Low Temperature Storage
1000h, T = - 40°C
IEC 60068 Part 2-1
06
Temperature Cycling
100 cycles
- 40°C + 125°C
IEC 60068 Part 2-14
Test Na
07
Power Cycling
20000 load cycles
Tj = 100K
IEC 60749-34
08
Vibration
Sinusoidal Sweep, 5 g,
x, y, z – axis, 2h/axis
IEC 60068 Part 2-6
Test Fc
09
Shock
Halfsinusoidal Pulse, 30 g,
x, y, z direction, 3x/direction
IEC 60068 Part 2-27
Test Ea
10
Tensile Strength
No
01
02
03
IEC 60747
IEC 60068 Part 2-67
IEC 60068 Part 2-21
Test Ua1
SEMIKRON Standard Qualification Test Program
3
Confidential
Qualification Standards - SEMiX™
Failure Criteria:
IGSS / IGES
IDSS / ICES
RDS(on) / VCE(sat)
VGS(th) / VGE(th)
:
:
:
:
Rth(j-c)
thjh
Visol
:
:
+ 100 % of the upper specification limit
+ 100 % of the upper specification limit
+ 20 % of the initial value
+ 20 % of the upper specification limit
- 20 % of the lower specification limit
+ 20 % of the initial value
not below the specification limit
Failure Criteria for Module Qualification
4
Confidential
Qualification Standards - SEMiX™
Contact Resistance of Sense and Auxiliary Contacts
Set-up:
short circuit bonded or continuous copper area DBC,
current sensor contact pads
max. change: 400 mΩ for
ΔRc:
C
o
n
d
a
i
t
i
o
n
s
:
m
e
a
s
.
c
u
l
i n
r
r
e
n
t
:
1
0
m
A
(
p
u
l s
e
)
p
a
i
,
5
V
r
o
v
1
0
1
T
e
m
p
e
r
a
t
u
r
e
C
y
c
0
f
p
o
l
0
i
t
n
a
s
(
g
c
y
=
e
c
l
l
2
i
m
e
s
2
5
0
i
0
t
a
Ω
m
t
i
o
p
e
r
p
i n
)
n
I
E
C
6
0
0
6
8
P
a
r
t
2
-
1
4
g
-
4
0
°
C
+
1
°
C
T
e
s
t
N
a
SEMIKRON Additional Reliability Test Program
5
Confidential
Contents





Basics of electrical spring contacts
Micro-vibration
Temperature cycling
Industrial atmosphere
Shock & Vibration
6
Confidential
Basics on electrical spring contacts
mating and
unmating force
contact force
Rc
typ. 50N/mm²
typ. 10N/mm²
20-100N/mm²
Types of electrical pressure contact
7
Confidential
Basics on electrical spring contacts
 Metallic platings
(Mating/un-mating forces &
contact forces):
 Contact forces in pressure
contacts of power modules:
 SnPb or Sn
-
2.5 - 20 N
 Ag
-
1 - 20 N
 Ni / Au flash
-
1-2 N
 Ni / AuCo 0.2%
-
1-2 N
 Mini SKiiP
 SEMiX
5-6 N
3-5 N
Plating systems for different pressure ranges
8
Basics on electrical spring contacts
Confidential
(P. Slade, Electrical Contacts, 1999)
Electrical contact is formed by A-Spots
9
Confidential
Basics on electrical spring contacts
a – spot radius /
µm
constriction
resistance / 
0,01
0,88
0,1
8,8 · 10-2
1
8,8 · 10-3
10
8,8 · 10-4
O.K. for 20 A
100
8,8 · 10-5
O.K. for 200 A
no significant
T-rise
(P. Slade, Electrical Contacts, 1999)
a-Spot radius on Cu for different currents
10
Basics on electrical spring contacts
Function
Typ. voltage range
Typ. current range
Impact of resistance change
MiniSKiiP
Confidential
Sensor Contact
Control Contact
Load Contact
0V to 5V
nA to mA
High
-15V to 15V
mA to 3A
Low
2V to 1700V
up to 20A
Very low
SEMiX
Different application ranges for electrical pressure contacts
11
Confidential
MiniSKiiP contact spring:
The contact springs for MiniSKiiP II are made of “K88”, a
copper alloy by German supplier “Wieland”.
Thickness of the spring material: 0.3 mm  0.05 mm
The contact spring is silver plated. The thickness of that
plating is varying over the springs surface and given in
the sketch below. To reduce tarnishing, the silver plating
is passivated by an additional inorganic conversion
layer (SnCl2) or a metallic plating with a thickness <<
1µm.
MiniSKiiP II Contact spring
12
Confidential
Contents





Basics of electrical spring contacts
Micro-vibration
Temperature cycling
Industrial atmosphere
Shock & Vibration
13
Confidential
Micro-vibration
clamping
fixture
piezo actuator
contact force
R
I V
PCB
PCB
spring pins
fixing screw
module housing
ΔRc
DBC
mounting plate
Tribometer Test – Schematic Set-up
14
Micro-vibration
Confidential
Source:
P.G.Slade: Electrical contacts:
principles and application, Marcel
Dekker, Inc. 1999, pp 343-345
Classification of micro-vibration test results
15
Confidential
Micro-vibration
Travel range  100 µm
Frequencies  20 Hz
Typical test conditions:
10 - 30 µm
5-10 Hz
Tribometer (A) - Test equipment for micro-vibration
16
Confidential
Micro-vibration
MiniSKiiP II. Generation Spring / PCB HAL SnPb
0,010
pair of springs #1
0,005
pair of springs #2
Delta R [Ohm]
0,000
-0,005
-0,010
Test conditions:
Frequency:
Amplitude:
Sample Rate:
Cycles:
1 Hz
50µm
5s
4,65 Mio.
(Test time:
~54 days)
-0,015
-0,020
-0,025
-0,030
0,0E+00
1,0E+06
2,0E+06
3,0E+06
4,0E+06
5,0E+06
number of cycles
Micro-vibration test result on Ag-Spring contact system
17
Confidential
Contents





Basics of electrical spring contacts
Micro-vibration
Temperature cycling
Industrial atmosphere
Shock & Vibration
18
Confidential
Temperature cycling of contact system
Experimental parameters
• Temperature cycling test: -40°C to +125°C
• During T-cycling: no current load on contacts
• Rc test: 10mA, 5V voltage limitation in open circuit
• Testing current over a pair of spring pins
• Rc limit: 400m
per pair of spring pins
(after 100 cycles)
I V
FR4
PCB
Rc1
Rc4
SnPb
K88 Ag plated
Initial R depends on
• Rc of 4 pressure contacts
• current paths
Rc2
DBC
Al
Rc3
Cu
Al2O3
General set-up of TC contact resistance tests
19
Confidential
Temperature cycling of contact system
MiniSKiiP II. Generation / PCB SnPb
500
Standard Lead PCB
450
#1
#2
Specification limit
#3
#4
400
delta Rc / mOhm
#5
#6
350
300
250
200
150
100
50
MA 040435
0
0
20
40
60
80
100
120
140
160
180
200
number of temperature cycles
Temperature cycling results for contact resistance tests
20
Confidential
Temperature cycling of contact system
MiniSKiiP II. Generation / PCB Ni/Au flash
500
RoHS compatible
450
#0
#7
#8
#9
#10
#11
#12
Specification limit
delta Rc / mOhm
400
350
300
250
C
200
150
100
50
MA 040435
0
0
20
40
60
80
100
120
140
160
180
200
number of temperature cycles
Temperature cycling results for contact resistance tests
21
Confidential
Temperature cycling of contact system
MiniSKiiP II. Generation / different PCBs
500
050566
1 Chem. Sn PCB
450
Specification limit
2 Chem. Sn PCB
R [m]
400
1 Ni/Au-flash PCB
350
2 Ni/Au-flash PCB
300
1 HAL Sn PCB
2 HAL Sn PCB
250
1 HAL SnPb PCB
200
2 HAL SnPb PCB
150
100
50
0
0
50
100
150
200
250
number of temperture cycles
Temperature cycling results for contact resistance tests
22
Confidential
Contents





Basics of electrical spring contacts
Micro-vibration
Temperature cycling
Industrial atmosphere
Shock & Vibration
23
Confidential
Industrial atmosphere
ISA-S71.04-1985 Standard:
Environmental Conditions for Process Measurement and Control Systems: Airborne Contaminants
There are four classes of industrial atmospheres with respect to copper reactivity.
G1 – Mild
An environment sufficiently well-controlled such that corrosion is not a factor in determining
equipment reliability.
G2 – Moderate
An environment in which the effects of corrosion are measurable and may be a factor in
determining equipment reliability.
G3 – Harsh
An environment in which there is a high probability that corrosive attack will occur.
These harsh levels should prompt further evaluation resulting in environmental controls
or specially designed and packed equipment.
GX – Severe
An environment in which only specially designed and packaged equipment would be
expected to survive. Specifications for equipment in this class are a matter of negotiations
between user and supplier.
Corrosive Atmosphere Test Conditions
condition
unit
H2 S
NO2
Cl2
SO2
T
RH
duration
[ppm]
[ppm]
[ppm]
[ppm]
[°C]
%
days
ISA-S71.04
class GX
DIN EN 60068-2- IEC 60068- IEC 60068- SEMIKRON
test
60 Ke
2-43
2-42
method 3
Kd
Kc
conditions
>0.05
>1.25
>0.1
>0.3
25
<50%
0.1
0.2
0.02
10-15
30
75
21
25
75
10
25
25
75
10
0.4
0.5
0.1
0.4
25
75
21
EN 60721-3-3
class 3C2
0.36
0.53
0.1
0.38
Corrosive atmosphere conditions
24
Industrial atmosphere
Confidential
IEC 60068-2-43
Atmosphere:
10 ppm H2S
Temperature:
25°C
Relative humidity: 75 %
Volume flow:
>volume*3/h
Duration:
10 days
No current load during storage
SEMiX with HAL SnPb PCB in industrial atmosphere
25
Confidential
Industrial atmosphere
Corrosive atmosphere results: IEC 60068-2-43
Module
Rc [m]
GT/ET
GB/EB
GT/ET
GB/EB
Module
Rc [m]
GT/ET
GB/EB
GT/ET
GB/EB
#1
#2
#3
#4
Rc before Rc after Rc before Rc after Rc before Rc after Rc before Rc after
[m]
[m]
[m]
[m]
[m]
[m]
[m]
[m]
219
222
218
221
230
236
225
217
248
247
251
268
225
232
230
236
3
3
6
-8
-1
17
7
6
#5
#6
#7
#8
Rc before Rc after Rc before Rc after Rc before Rc after Rc before Rc after
[m]
[m]
[m]
[m]
[m]
[m]
[m]
[m]
220
223
214
214
226
231
222
226
225
216
245
250
237
243
234
237
3
0
5
4
-9
5
6
3
Cu normal
Cu normal
Cu normal
Ag normal
Mass before Mass after
Test
Test
[g]
[g]
2,1528
2,164
2,2612
2,2721
2,1938
2,2044
35,544
35,5443
Mass Gain
[%]
0,5203
0,4820
0,4832
0,0008
SEMiX with HAL SnPb PCB in industrial atmosphere
26
Industrial atmosphere
Confidential
SEMIKRON Test Conditions
Atmosphere:
0.5 ppm NO2
0.4 ppm H2S
0.1 ppm Cl2
0.4 ppm NO2
Temperature:
25°C
Relative humidity: 75 %
Volume flow:
>volume*3/h
Duration:
21 days
No current load during storage
Corrosive atmosphere test: SEMIKRON Conditions
27
Confidential
Industrial atmosphere
Kontakt
T1/T2
G1/Ex1
G2/Ex2
#1A
Rc before Rc after
[m]
[m]
117,9
119,0
119,5
119,8
83,1
85,0
Rc
[m]
1,11
0,22
1,86
#4A
Rc before Rc after
[m]
[m]
98,8
100,8
102,3
102,7
87,4
88,6
Rc
[m]
2,05
0,39
1,21
Kontakt
T1/T2
G1/Ex1
G2/Ex2
#2A
Rc before Rc after
[m]
[m]
127,6
129,4
117,8
118,4
92,5
93,0
Rc
[m]
1,75
0,61
0,51
#5A
Rc before Rc after
[m]
[m]
111,7
113,3
105,3
107,8
76,7
77,6
Rc
[m]
1,66
2,5
0,94
Kontakt
T1/T2
G1/Ex1
G2/Ex2
#3A
Rc before Rc after
[m]
[m]
123,8
125,6
119,6
121,4
87,6
87,9
Rc
[m]
1,83
1,76
0,27
#6A
Rc before Rc after
[m]
[m]
99,0
101,0
98,8
100,8
90,4
94,4
Rc
[m]
1,98
1,98
4,01
SEMiX with HAL SnPb PCB in industrial atmosphere
28
Confidential
Contents





Basics of electrical spring contacts
Micro-vibration
Temperature cycling
Industrial atmosphere
Shock & Vibration
29
Vibration & Shock on contact system
Confidential
Standard test conditions:
Sinusoidal sweep
10 - 1000 Hz
10-12 Hz: constant
amplitude = 17.5mm (pp)
12-1000 Hz: constant
acceleration = 5g
1 Octave/min.
 6:40 min per sweep
20 sweeps per axis
 2:20 hrs per axis
Vibration Test (external test lab) - Test conditions
30
Confidential
Vibration & Shock on contact system
Current Monitoring
MV 200
10
100
10
100
DUT 1
-
DUT 2
+12V
10
100
DUT n
Contact Monitoring
(detects contact breaks >1µs)
Vibration test (external test lab) – Monitoring for contact break
31
Vibration & Shock on contact system
Confidential
No contact interruption >1µs detected
Vibration test (external test lab) – Test results SEMiX
32
Vibration & Shock on contact system
Confidential
Vibration test (external test lab) – Test results MiniSKiiP
33
Vibration & Shock on contact system
Confidential
Standard test conditions:
half-sinusoidal pulse
peak acceleration 30g
shock width 18ms
3 shocks in each direction
(±x, ±y, ±z)
18 shocks in total
Shock Test (external test lab) - Test conditions
34
Confidential
Qualification of functional modules
Typ:
Name:
SKiiP 26 NHB 065 V1
Parameter:
Lechner
Vormessung Schock und Vibration-Test
MA:
03/08/26
Dat.:
17.10.2003
25°C
statische
Werte
Nr.
37
37
37
37
37
37
37
37
Zweig
IGBT 1
IGBT 3
IGBT 5
IGBT 2
IGBT 4
IGBT 6
D B+
Brake
IC=1mA
VGE = + 25V
VGE = - 25V
IC =50A
IC = 25A
VR = 612V
VGE = VCE
VCE = 0V
VCE = 0V
VGE = 15V
VGE = 0V
VGE = 0V
VGE(th)
3,86
3,86
3,87
3,86
3,86
3,85
V
V
V
V
V
V
V
IGES
< 10
< 10
< 10
< 10
< 10
< 10
nA
nA
nA
nA
nA
nA
nA
IGES
< 10
< 10
< 10
< 10
< 10
< 10
nA
nA
nA
nA
nA
nA
nA
3,86
V
< 10
nA
< 10
nA
Typ:
V
V
V
V
V
V
V
1
V
Name:
SKiiP 26 NHB 065 V1
Parameter:
VCEsat
2,15
2,14
2,16
2,05
2,07
2,09
3,00
2,16
VCERV
1,49
1,50
1,51
1,56
1,53
1,48
1,69
V
V
V
V
V
V
V
V
Lechner
Nachmessung Schock und Vibration-Test
ICES
3
2
3
2
2
2
1,6
1,1
V(BR)CES
IR = 10 mA
µA
µA
µA
µA
µA
µA
µA
µA
µA
V(BR)CES
734
729
726
728
739
737
728
733
MA:
03/08/26
Dat.:
15.01.2004
V
V
V
V
V
V
V
V
V
Nr.
37
37
37
37
37
37
37
37
Zweig
IGBT 1
IGBT 3
IGBT 5
IGBT 2
IGBT 4
IGBT 6
D B+
Brake
VGE = + 25V
VGE = - 25V
IC =50A
IC = 25A
VR = 612V
V(BR)CES
VGE = VCE
VCE = 0V
VCE = 0V
VGE = 15V
VGE = 0V
VGE = 0V
IR = 10 mA
V
V
V
V
V
V
V
IGES
< 10
< 10
< 10
< 10
< 10
< 10
nA
nA
nA
nA
nA
nA
nA
IGES
< 10
< 10
< 10
< 10
< 10
< 10
nA
nA
nA
nA
nA
nA
nA
VCEsat
2,37
2,40
2,36
2,36
2,42
2,39
3,88
V
< 10
nA
< 10
nA
2,43
V
V
V
V
V
V
V
1
V
VCERV
1,59
1,63
1,62
1,73
1,69
1,64
1,83
V
V
V
V
V
V
V
V
ICES
4,6
4,6
4,2
3,9
3,7
3,8
1,1
0,4
µA
µA
µA
µA
µA
µA
µA
µA
µA
V(BR)CES
733
735
728
736
743
737
728
740
in spec.
ICES
in spec.
VGE(th) in spec.
VCE(sat) in spec.
3.6kV o.k.
Rth(j-h) not tested
IC=1mA
VGE(th)
3,88
3,88
3,89
3,88
3,88
3,86
IGES
Viso
25°C
statische
Werte
6 devices tested
(VF in spec.)
V
V
V
V
V
V
V
V
V
Vibration & shock test - Results MiniSKiiP® II
35
Confidential
Thank You Very Much For Your Kind Attention
36