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1
Confidential
Reliability
of
Spring Contacts Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration
2
Confidential
Comparison Spring contact / Solder contact
General Considerations
++ Excellent
+ Good
o Adequate
- Bad
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 Ad
van
tag
es
Rework and field service + o
Contact resistance o ++
Contact stability in temperature cycling + o
No fatigue of solder contacts (cold
joints)
Contact stability in industrial environment + +
Cu
sto
mer
Co
nc
ern
s
Contact stability under shock and vibration + o No fractures as in
solder contacts
3
Confidential
SEMIKRON Standard Qualification Test Program
Qualification Standards – SEMiX™
No Test Test Conditions Standard
01
High Temperature Reverse Bias
IGBT 600/1200 V 1700 V
1000h, VGE = 0V 95% VDSmax / VCEmax,
Tc = 140°C Tc = 125°C
IEC 60747
02 High Temperature
Gate Stress 1000h, VGSmax / VGEmax,
Tvjmax IEC 60747
03 High Humidity
High Temperature Reverse Bias
1000h , 85°C, 85% RH VDS/VCE= 80% VDSmax/VCEmax,
max. 80V, VGE = 0V IEC 60068 Part 2-67
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 IEC 60068 Part 2-21
Test Ua1
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Confidential
Failure Criteria for Module Qualification
Qualification Standards - SEMiX™
Failure Criteria:
IGSS / IGES : + 100 % of the upper specification limit IDSS / ICES : + 100 % of the upper specification limit RDS(on) / VCE(sat) : + 20 % of the initial value VGS(th) / VGE(th) : + 20 % of the upper specification limit - 20 % of the lower specification limit Rthjh : + 20 % of the initial value Visol : not below the specification limit
Rth(j-c)
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Confidential
SEMIKRON Additional Reliability Test Program
Qualification Standards - SEMiX™
Contact Resistance of Sense and Auxiliary Contacts
Set-up: short circuit bonded or continuous copper area DBC, current sensor contact pads ΔRc: max. change: 400 mΩ for a pair of pins (= 200 mΩ per pin) Conditions: meas. current: 10 mA (pulse), 5V voltage limitation
01 Temperature Cycling 100 cycles
-40°C + 125°C IEC 60068 Part 2-14
Test Na
6
ConfidentialContents
Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration
7
Confidential
Types of electrical pressure contact
contact force
mating and unmating force
Rc
Basics on electrical spring contacts
typ. 50N/mm² typ. 10N/mm² 20-100N/mm²
8
Confidential
Plating systems for different pressure ranges
Contact forces in pressure contacts of power modules:
Mini SKiiP 5-6 N
SEMiX 3-5 N
Metallic platings (Mating/un-mating forces & contact forces):
SnPb or Sn - 2.5 - 20 N
Ag - 1 - 20 N
Ni / Au flash - 1-2 N
Ni / AuCo 0.2% - 1-2 N
Basics on electrical spring contacts
9
Confidential
Electrical contact is formed by A-Spots
(P. Slade, Electrical Contacts, 1999)
Basics on electrical spring contacts
10
Confidential
a-Spot radius on Cu for different currents
a – spot radius /µm
constrictionresistance /
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 Ano significantT-rise
(P. Slade, Electrical Contacts, 1999)
Basics on electrical spring contacts
11
Confidential
Different application ranges for electrical pressure contacts
Basics on electrical spring contacts
Function Sensor Contact Control Contact Load Contact Typ. voltage range 0V to 5V -15V to 15V 2V to 1700V Typ. current range nA to mA mA to 3A up to 20A Impact of resistance change High Low Very low MiniSKiiP
SEMiX
12
Confidential
MiniSKiiP II Contact spring
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.
13
ConfidentialContents
Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration
14
Confidential
Tribometer Test – Schematic Set-up
contact forcepiezo actuator
spring pins fixing screw
R
clampingfixture
PCB
module housing
mounting plate
PCBI V
DBC
ΔRc
Micro-vibration
15
Confidential
Classification of micro-vibration test results
Source:
P.G.Slade: Electrical contacts: principles and application, Marcel Dekker, Inc. 1999, pp 343-345
Micro-vibration
16
Confidential
Tribometer (A) - Test equipment for micro-vibration
Travel range 100 µm Frequencies 20 Hz
Typical test conditions:10 - 30 µm 5-10 Hz
Micro-vibration
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Confidential
Micro-vibration test result on Ag-Spring contact system
Test conditions:
Frequency: 1 Hz Amplitude: 50µmSample Rate: 5sCycles: 4,65 Mio.
(Test time: ~54 days)
MiniSKiiP II. Generation Spring / PCB HAL SnPb
-0,030
-0,025
-0,020
-0,015
-0,010
-0,005
0,000
0,005
0,010
0,0E+00 1,0E+06 2,0E+06 3,0E+06 4,0E+06 5,0E+06
number of cycles
De
lta
R [
Oh
m]
pair of springs #1
pair of springs #2
Micro-vibration
18
ConfidentialContents
Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration
19
Confidential
General set-up of TC contact resistance tests
PCB
Al2O3Cu
Al
SnPb
I V
Rc1 Rc4
Rc2Rc3
DBC
K88 Ag plated
FR4
Initial R depends on
• Rc of 4 pressure contacts
• current paths
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: 400mper pair of spring pins
(after 100 cycles)
Temperature cycling of contact system
20
Confidential
Temperature cycling results for contact resistance tests
Temperature cycling of contact system
MiniSKiiP II. Generation / PCB SnPb
0
50
100
150
200
250
300
350
400
450
500
0 20 40 60 80 100 120 140 160 180 200
number of temperature cycles
de
lta
Rc
/ m
Oh
m
#1
#2
#3
#4
#5
#6
Specification limit
MA 040435
Standard Lead PCB
21
Confidential
MiniSKiiP II. Generation / PCB Ni/Au flash
0
50
100
150
200
250
300
350
400
450
500
0 20 40 60 80 100 120 140 160 180 200
number of temperature cycles
del
ta R
c /
mO
hm
#0
#7
#8
#9
#10
#11
#12
Specification limit
MA 040435
C
Temperature cycling results for contact resistance tests
Temperature cycling of contact system
RoHS compatible
22
Confidential
Temperature cycling results for contact resistance tests
Temperature cycling of contact system
MiniSKiiP II. Generation / different PCBs
0
50
100
150
200
250
300
350
400
450
500
0 50 100 150 200 250
number of temperture cycles
R [
m
]
1 Chem. Sn PCB
2 Chem. Sn PCB
1 Ni/Au-flash PCB
2 Ni/Au-flash PCB
1 HAL Sn PCB
2 HAL Sn PCB
1 HAL SnPb PCB
2 HAL SnPb PCB
Specification limit
050566
23
ConfidentialContents
Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration
24
Confidential
Corrosive atmosphere conditions
ISA-S71.04-1985 Standard: Environmental Conditions for Process Measurement and Control Systems: Airborne ContaminantsThere 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 beexpected to survive. Specifications for equipment in this class are a matter of negotiations between user and supplier.
Industrial atmosphere
ISA-S71.04 DIN EN 60068-2-60 Ke
IEC 60068-2-43
IEC 60068-2-42 EN 60721-3-3
condition unit class GX method 3 Kd Kc class 3C2
H2S [ppm] >0.05 0.1 10-15 0.4 0.36NO2 [ppm] >1.25 0.2 0.5 0.53Cl2 [ppm] >0.1 0.02 0.1 0.1SO2 [ppm] >0.3 25 0.4 0.38
T [°C] 25 30 25 25 25RH % <50% 75 75 75 75
duration days 21 10 10 21
SEMIKRON test
conditions
Corrosive Atmosphere Test Conditions
25
Confidential
SEMiX with HAL SnPb PCB in industrial atmosphere
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
Industrial atmosphere
26
Confidential
SEMiX with HAL SnPb PCB in industrial atmosphere
ModuleRc before Rc after Rc before Rc after Rc before Rc after Rc before Rc after
[m] [m] [m] [m] [m] [m] [m] [m]
GT/ET 219 222 218 221 230 236 225 217GB/EB 248 247 251 268 225 232 230 236
Rc [m] GT/ETGB/EB
ModuleRc before Rc after Rc before Rc after Rc before Rc after Rc before Rc after
[m] [m] [m] [m] [m] [m] [m] [m]
GT/ET 220 223 214 214 226 231 222 226GB/EB 225 216 245 250 237 243 234 237
Rc [m] GT/ETGB/EB -9 5 6 3
3 0 5 4
67
-86
3-1
317
#1 #2 #3 #4
#8#7#6#5
Corrosive atmosphere results: IEC 60068-2-43
Industrial atmosphere
Mass before Test
Mass after Test Mass Gain
[g] [g] [%]Cu normal 2,1528 2,164 0,5203Cu normal 2,2612 2,2721 0,4820Cu normal 2,1938 2,2044 0,4832Ag normal 35,544 35,5443 0,0008
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Confidential
Corrosive atmosphere test: SEMIKRON Conditions
SEMIKRON Test Conditions
Industrial atmosphere
Atmosphere: 0.5 ppm NO2
0.4 ppm H2S0.1 ppm Cl20.4 ppm NO2
Temperature: 25°C
Relative humidity: 75 %
Volume flow: >volume*3/h
Duration: 21 days
No current load during storage
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Confidential
SEMiX with HAL SnPb PCB in industrial atmosphere
Industrial atmosphere
Rc before Rc after Rc Rc before Rc after RcKontakt [m] [m] [m] [m] [m] [m]
T1/T2 117,9 119,0 1,11 98,8 100,8 2,05G1/Ex1 119,5 119,8 0,22 102,3 102,7 0,39G2/Ex2 83,1 85,0 1,86 87,4 88,6 1,21
Rc before Rc after Rc Rc before Rc after RcKontakt [m] [m] [m] [m] [m] [m]
T1/T2 127,6 129,4 1,75 111,7 113,3 1,66G1/Ex1 117,8 118,4 0,61 105,3 107,8 2,5G2/Ex2 92,5 93,0 0,51 76,7 77,6 0,94
Rc before Rc after Rc Rc before Rc after Rc Kontakt [m] [m] [m] [m] [m] [m]
T1/T2 123,8 125,6 1,83 99,0 101,0 1,98G1/Ex1 119,6 121,4 1,76 98,8 100,8 1,98G2/Ex2 87,6 87,9 0,27 90,4 94,4 4,01
#1A #4A
#2A
#3A #6A
#5A
29
ConfidentialContents
Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration
30
Confidential
Vibration Test (external test lab) - Test conditions
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 & Shock on contact system
31
Confidential
Vibration test (external test lab) – Monitoring for contact break
Vibration & Shock on contact system
Current MonitoringMV 200
Contact Monitoring(detects contact breaks >1µs)
DUT 1
DUT 2
DUT n
10 100
10 100
10 100
+12V-
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Confidential
Vibration test (external test lab) – Test results SEMiX
No contact interruption >1µs detected
Vibration & Shock on contact system
33
Confidential
Vibration test (external test lab) – Test results MiniSKiiP
Vibration & Shock on contact system
34
Confidential
Shock Test (external test lab) - Test conditions
Standard test conditions:
half-sinusoidal pulse
peak acceleration 30g
shock width 18ms
3 shocks in each direction (±x, ±y, ±z) 18 shocks in total
Vibration & Shock on contact system
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Confidential
Vibration & shock test - Results MiniSKiiP® II
Name: MA:
Dat.:
Nr. Zweig VGE(th) V IGES nA IGES nA VCEsat V VCERV V ICES µA V(BR)CES V37 IGBT 1 3,86 V < 10 nA < 10 nA 2,15 V 1,49 V 3 µA 734 V37 IGBT 3 3,86 V < 10 nA < 10 nA 2,14 V 1,50 V 2 µA 729 V37 IGBT 5 3,87 V < 10 nA < 10 nA 2,16 V 1,51 V 3 µA 726 V37 IGBT 2 3,86 V < 10 nA < 10 nA 2,05 V 1,56 V 2 µA 728 V37 IGBT 4 3,86 V < 10 nA < 10 nA 2,07 V 1,53 V 2 µA 739 V37 IGBT 6 3,85 V < 10 nA < 10 nA 2,09 V 1,48 V 2 µA 737 V37 D B+ 3,00 1 1,69 V 1,6 µA 728 V37 Brake 3,86 V < 10 nA < 10 nA 2,16 V 1,1 µA 733 V
25°C
VGE = 15V
VR = 612V V(BR)CES
VGE = 0V VGE = 0V IR = 10 mA
Parameter: Vormessung Schock und Vibration-Test 17.10.2003
statische Werte
IC=1mA VGE = + 25V VGE = - 25V IC =50A IC = 25A
VGE = VCE VCE = 0V VCE = 0V
Typ: SKiiP 26 NHB 065 V1 Lechner 03/08/26
6 devices tested
IGES in spec.
ICES in spec.
VGE(th) in spec.
VCE(sat) in spec.
Viso 3.6kV o.k.
Rth(j-h) not tested
(VF in spec.)
Name: MA:
Dat.:
Nr. Zweig VGE(th) V IGES nA IGES nA VCEsat V VCERV V ICES µA V(BR)CES V37 IGBT 1 3,88 V < 10 nA < 10 nA 2,37 V 1,59 V 4,6 µA 733 V37 IGBT 3 3,88 V < 10 nA < 10 nA 2,40 V 1,63 V 4,6 µA 735 V37 IGBT 5 3,89 V < 10 nA < 10 nA 2,36 V 1,62 V 4,2 µA 728 V37 IGBT 2 3,88 V < 10 nA < 10 nA 2,36 V 1,73 V 3,9 µA 736 V37 IGBT 4 3,88 V < 10 nA < 10 nA 2,42 V 1,69 V 3,7 µA 743 V37 IGBT 6 3,86 V < 10 nA < 10 nA 2,39 V 1,64 V 3,8 µA 737 V37 D B+ 1 1,83 V 1,1 µA 728 V37 Brake 3,88 V < 10 nA < 10 nA 2,43 V 0,4 µA 740 V
Typ: SKiiP 26 NHB 065 V1 Lechner 03/08/26
Parameter: Nachmessung Schock und Vibration-Test 15.01.2004
statische Werte
25°C
IC=1mA 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
Qualification of functional modules
36
Confidential
Thank You Very Much For Your Kind Attention