1 Confidential Reliability of Spring Contacts n Basics of electrical spring contacts n...

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Confidential

Reliability

Spring Contacts Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration

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Comparison Spring contact / Solder contact

General Considerations

++ Excellent

+ Good

o Adequate

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

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 + +

Contact stability under shock and vibration + o No fractures as in

solder contacts

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SEMIKRON Standard Qualification Test Program

Qualification Standards – SEMiX™

No 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

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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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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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

ConfidentialContents

Basics of electrical spring contacts Micro-vibration Temperature cycling Industrial atmosphere Shock & Vibration

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Types of electrical pressure contact

contact force

mating and unmating force

Basics on electrical spring contacts

typ. 50N/mm² typ. 10N/mm² 20-100N/mm²

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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

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Electrical contact is formed by A-Spots

(P. Slade, Electrical Contacts, 1999)

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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)

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Different application ranges for electrical pressure 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

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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.

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Tribometer Test – Schematic Set-up

contact forcepiezo actuator

spring pins fixing screw

clampingfixture

module housing

mounting plate

PCBI V

Micro-vibration

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Classification of micro-vibration test results

Source:

P.G.Slade: Electrical contacts: principles and application, Marcel Dekker, Inc. 1999, pp 343-345

Micro-vibration

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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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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

0,0E+00 1,0E+06 2,0E+06 3,0E+06 4,0E+06 5,0E+06

number of cycles

pair of springs #1

pair of springs #2

Micro-vibration

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General set-up of TC contact resistance tests

Al2O3Cu

Rc1 Rc4

Rc2Rc3

K88 Ag plated

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

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Temperature cycling results for contact resistance tests

MiniSKiiP II. Generation / PCB SnPb

0 20 40 60 80 100 120 140 160 180 200

number of temperature cycles

Specification limit

MA 040435

Standard Lead PCB

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MiniSKiiP II. Generation / PCB Ni/Au flash

0 20 40 60 80 100 120 140 160 180 200

number of temperature cycles

Specification limit

MA 040435

RoHS compatible

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MiniSKiiP II. Generation / different PCBs

0 50 100 150 200 250

number of temperture cycles

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

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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

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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

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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

#1 #2 #3 #4

#8#7#6#5

Corrosive atmosphere results: IEC 60068-2-43

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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Corrosive atmosphere test: SEMIKRON Conditions

SEMIKRON Test Conditions

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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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

#3A #6A

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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

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Vibration test (external test lab) – Monitoring for contact break

Current MonitoringMV 200

Contact Monitoring(detects contact breaks >1µs)

10 100

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Vibration test (external test lab) – Test results SEMiX

No contact interruption >1µs detected

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Vibration test (external test lab) – Test results MiniSKiiP

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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

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Vibration & shock test - Results MiniSKiiP® II

Name: MA:

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

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:

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

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

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Thank You Very Much For Your Kind Attention

1 Confidential Reliability of Spring Contacts n Basics of electrical spring contacts n...

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