Isograph Reliability Software Overview of Prediction Methods.

Isograph Reliability Software

Overview of Prediction Methods


MIL-217 F Notice 2

...AEQbp


MIL-217 Categories• Hybrid• IA, Plated Through Holes• IA, Surface Mount Tech• External• Capacitor• Micro, EEPROM• Micro, Not EEPROM• Resistor• Diode, Low Frequency• Diode, High Frequency• Transistor, LF Bipolar• Transistor, LF FET

• Transistor, Unijunction• Transistor,HF HP Bipolar• Diode, Laser• Transistor,HF GaAs FET• Transistor,HF Si FET• Detector, Isolator, Emit• Thyristor, SCR• Transistor,LN HF Bipolar• Hybrid Layer• Laser, Helium/Argon• Laser, CO2 Sealed• Laser, CO2 Flowing


MIL-217 Categories• Laser, NdY/Ruby, Krypton• Laser, NdY/Ruby, Xenon• Tube, NOT TWT/Magnetron• Tube, Travelling Wave• Tube, Magnetron• Micro, SAW Device• Micro, VHSIC/VLSI CMOS• Microprocessor, Digital• Micro, PLA/PAL• Micro, Linear• Micro, Digital• Micro, GaAs MMIC

• Transformer• Coil• Meter, Elapsed Time• Synchro/Resolver• Motor• Relay, Solid State/TD• Relay, Mechanical• Switch• Circuit Breaker• Fuse• Filter, Electronic• Lamp


MIL-217 Categories• Quartz Crystal• Meter, Panel• Miscellaneous• Connection• Connector, General• Connector, Socket• Alpha-Numeric Display• Micro, GaAs Digital• Bubble Memory


Mil-217 Variable Wirewound Resistor

EQVRTAPSbp

))273

273(exp()358

273exp(0062.0 5

TSTb

792.025

)( 23

TAPSTAPS

N


Mil-217 Variable Wirewound Resistor

R= 1.0 for 10 to 2K ohms, 1.4 for >2K to 5K ohms and 2.0 for >5K to 20K ohmsApplied

Voltage/RatedVotage

V

0 to 0.1 1.10>0.1 to 0.2 1.05>0.2 to 0.6 1.00>0.6 to 0.7 1.10>0.7 to 0.8 1.22>0.8 to 0.9 1.40>0.9 to 1.0 2.00


Mil-217 Variable Wirewound ResistorQuality

QS 0.02R 0.06P 0.2M 0.6

MIL-R-27208 3.0Lower 10

EnvironmentE

GB 1.0GF 2.0GM 12NS 6NU 20AIC 5AIF 8AUC 9AUF 15ARW 33SF 0.5MF 18ML 48CL 870


Bellcore (Telcordia) TR-332 Issue 6• Steady-state failure rate• First year multiplier• Methods :

– Method I– Method II - Unit– Method II - Devices– Method III(a) - Unit– Method III(a) - Devices– Method III(b) - Unit– Method III(b) - Devices– Method III(c) - Unit


Bellcore Categories• Hybrid• IC, Digital• IC, Gate Arrays, PAL• IC, Microprocessor• IC, Analog/Linear• IC, Static RAM• IC, Dynamic RAM• IC, ROM/PROM/EPROM• Opto-Electronic Device• Alpha-Numeric Display• Transistor• Diode

• Thermistor• Resistor, Fixed• Resistor, Variable• Resistor, Network• Capacitor• Inductor• Connector• Switch• Relay• Rotating Device• Miscellaneous• Computer System


Non-Operating Periods

PartTypes

GroundActive toGroundPassive

AirborneActive toAirbornePassive

AirborneActive toGroundPassive

NavalActive toNavalPassive

NavalActive toGroundPassive

SpaceActive toSpacePassive

SpaceActive toGroundPassive

IntegratedCircuits

0.08 0.06 0.04 0.06 0.05 0.1 0.3

Diodes 0.04 0.05 0.01 0.04 0.03 0.2 0.8… … ………


Phased Missions• Phase time length• Environment• Temperature• Operating/Non-operating


NSWC Standard• Mechanical Components• Combines statistical data with physics of

failure


NSWC Categories• Seal, Static or Gasket• Seal, Dynamic• Spring, Compression/Ext.• Spring, Torsion• Washer, Curved• Washer, Waved• Washer, Belleville• Spring, Cantilever• Spring, Beam• Solenoid• Valve, Poppet• Valve, Sliding Action

• Bearing• Gear• Spline• Actuator• Pump Shaft• Pump Fluid Driver• Filter• Brake Lining• Clutch Lining• Electric Motor Brush• Electric Motor Winding• Fastener


NSWC Categories• Rod or Shaft• Housing or Casing• Compressor


Overview of RDF 2000 Telcordia/MIL-217 failure rate is function of :

• Physical characteristics of component• Operating conditions – temperature and

environment• Test data (field/laboratory)• Component quality


Overview of RDF 2000 RDF 2000 failure rate is function of :

• Physical characteristics of component• Operating conditions – temperature only


Overview of RDF 2000 Why does RDF 2000 ignore environment and quality?

• Environment“Observed defects are due to thermo-mechanical constraints

on components mounted on PCBs…in studied environments no defect due to shock or vibration was observed…”

• Quality“… choose manufacturers who have quality best practice…in

these conditions no longer necessary to take into consideration quality factors…”


Overview of RDF 2000 • Varying operational conditions are considered

using multiple phases• Phase modes are :

– On/off– Permanent/dormant (in storage)

• Workbench allows up to 5 separate phases• Phases applied at the Workbench block level


Overview of RDF 2000 RDF 2000 applies the following factors for considering the effects of temperature :

• The effect of operating the component at a particular temperature whilst it is switched on (PI_t).

• The effect (PI_n) of :– Varying ambient temperature when the component is in storage

or permanently workingOR– The temperature rise/fall when the component is cycled

between switched on and switched off.• Both PI_t and PI_n are summed over all the phases


RDF 2000 Example• Consider single phase, 100% permanently

working• Data required for block:

– Tae, outside ambient temperature– Tal, ambient temperature around card– Tac, card (PCB) temperature– dT, variation in outside ambient temperature– N, number of thermal cycles per year


RDF 2000 Example

Calculate PI_t sum• Calculate junction temperature based on the

component power, thermal resistance and the card temperature. Eg Tj = Tac + deltatj

• Use the junction temperature to look up PI_t• Repeat this for each phase• Sum PI_t over the phases

offon

iiy

it

.

1


RDF 2000 Example

• For example consider diode with Tac = 35, deltatj = 40 hence Tj = 75. From p 36 of standard look up PI_t as 4.4 .

• Thus Pi_t sum = 4.4 * 100 / 100 = 4.4

offon

iiy

it

.

1


RDF 2000 Example

Calculate PI_n sum• Use the number of cycles per year calculate PI_n:

– <= 8760 cycles per year then PI_n = N ^ 0.76– > 8760 cycles per year then PI_n = 1.7 * N ^ 0.60

• Calculate deltati:– For on/off phase then deltati = (deltatj/3 + Tac – tae– For a permanently on or dormant phase then deltati = dT

• Sum PI_n and deltati over the phases

68.0

1).( ii

j

in


RDF 2000 Example

• For example consider permanently working diode with N = 12000 cycles per year and dT = 15.

• PI_n = 1.7 * 12000^0.60 = 476• Deltati = 15 ^ 0.68 = 6.3• Thus PI_n sum = 476 * 6.3 = 2999

68.0

1).( ii

j

in


RDF 2000 Example

• Simplified form of failure rate equation for diode is :(Die base failure rate) * PI_t sum + 2.75e-3 * (package base failure rate) * PI_n sum

• So typical example using values calculated before:= 0.7 * 4.4 + 2.75e-3 * 2.0 * 2999 = 19.57

Isograph Reliability Software Overview of Prediction Methods.

Documents

Transcript of Isograph Reliability Software Overview of Prediction Methods.