1. Reliability Assessment & Growth
Objectives
Basic Understanding of Conventional and Reliability Statistics
6 Sigma Quality Levels and Basic Statistical Data Analysis
Introduction to Reliability Prediction Methods and Databases
Environmental, Electrical, Mechanical and other Stresses
Introduction to Reliability Growth Strategies
Defining a COMMON Reliability Prediction Database for your team
Calculate a Reliability Prediction using basic parts count methods
Define economically viable warranty using the Reliability Prediction

2. Reliability Assessment & Growth
Deliverable 1 – Individual for each Block (Excel & 1 PPT Slide)
Decide which Reliability Database your team will use
Determine your applicable environment
Update your BLOCK BOM (Bill of Materials) to current design
Find the appropriate “p” stress factors and l values
Compile your overall BLOCK l and MTBF using the Excel Tool
Summarize in 1 PPT slide to include in your block slide package
Conclusions or takeaways about …
What is the total block FITs and resultant MTBF?
What are the dominant parts for unreliability?
What if anything could be done to improve the reliability?

3. Reliability Assessment, Growth
Deliverable 2 – Product Level/Team (Excel File & PPT Slides)
Compile the overall Product l (Fits) and MTBF by Totaling Block l
Calculate R(warranty) (100 - % failures) in the original Warranty Period
Then, find a modified warranty period by finding “t” for R(t) = 0.99 (99%)
Decide as a Team which direction to proceed below;
A: Eliminate/change “low hanging fruit” reliability problem components to improve your design to meet the original warranty target
B: Change your product warrant to Time = R(99%) However your warranty must be reasonable for your product type
Update your requirements table, slides, etc if needed to reflect new warranty
- Summarize the above calculations to show the following in PPT slides
Conclusions or takeaways about …
Use the Template Slide or Show a Table of Block Numbers, Names, Block l, Total l and MTBF
Identify the dominant parts for unreliability? ( highest individual l)
Did you Change the Warranty Period, or Improve the Design, or Both ?
What design improvements can you or or will you make to increase reliability?
Tell the story of what happened in this exercise

4. Reliability Assessment, Growth
Optional Deliverable – Product Level/Team (PPT Slide)
Compile a 10 year life stress model using Voltage, Thermal and Vibration stresses for your product that quantifies the following (see template)
Total # of power cycles
Max Voltage Input
Max Range of thermal cycles
Max Number of thermal cycles
Max Vibration in Grms and Total Duration
Max Shock Grms and Total Repetitions
Document the Stress Model in ppt slide
For each of the above stresses, determine the acceleration strategy.
For Coffin-Manson thermal cycle, use exponent of 2 to be conservative
Compile and Document the Reliability Growth Plan by using the Template as shown
Add any additional details regarding the plan such as number of samples tested

5. 595 Standard Failure Rates in FITs
Component Type
Method A - l
Method B - l
Method C - l
Method D - l
Method E - l
BJT/FET
5.0
3.8
3.2
7.6
4.0
Switch
44.0
30.0
1.0
20.0
Metal Film Res
0.7
2.5
0.05
0.2
Carbon Res
18.2
2.7
1.1
2.6
Varistor, tc Res
6.0
10.0
Electrolytic Cap
210
22.0
120
16.0
Polyester Cap
8.5
2.0
3.0
0.5
7.0
Tantalum Cap
15.0
8.0
Ceramic Cap
0.25
1.2
Si PN, Shottkey, PIN Diode
2.4
1.6
3.6
Zener Diode
13.6
17.4
18.8
70.0
LED
9.0
280
65.0
BJT Dig IC <100 Gates
138
2.3
6.7
BJT Dig IC < 1000 Gates
150
1.5
MOS Dig IC < 1000 Gates
27.3
301
13.3
MOS Dig IC => 1000 Gates
55.0
550
2.2
31.0
EM Coil Relay
385
302
220
715
SSR, Optocoupler
105
47.0
190
12.0
BJT Linear IC < 1000 Transistors
14.0
27.0
4.3
50.0
MOS Linear IC < 1000 Transistors
19.0
54.0
Transformer < 1VA
33.0
90.0
60.0
Transformer > 1VA

6. 595 Standard Failure Rates in FITs
Component Type
Method A - l
Method B - l
Method C - l
Method D - l
Method E - l
Plastic Shell Connector, Plug, Jack
100.0
55.0
150.0
120.0
105.0
Metal Shell Connector, Plug, Jack
33.0
18.0
57.0
40.0
35.0
Pb, NCd, Li, Lio, NmH Battery
7.0
1.0
50.0
8.0
22.0
Quartz Crystal Thru Hole
115.0
113.8
113.2
117.6
114.0
Quartz Crystal SMT
15.0
34.0
30.0
51.0
20.0
Quartz Oscillator Module CMOS
10.0
12.5
10.5
Diode Bridge
4.8
1.6
3.6
2.4
LED Display
19.0
280
165.0
21.0
LCD Display
119.0
215.0
380
1165.0
206.0
BJT Linear IC > 1000 Transistors
217.0
41.3
91.0
MOS Linear IC > 1000 Transistors
29.0
74.0
113.3
Metallic Fuse
12.0
27.0
Photocell-diode Optical Sensor
77.0
111.0
Peizo Ultrasonic Transducer
1200
900
2000
1450
Proximity Sensor
350
1000
750
810
550

7. 595 Standard Stress Factors
Factor Definitions (may not represent standard models)
pT = Temperature Stress Factor = e[Ta/(Tr-Ta)] – 0.4
Where Ta = Actual Max Operating Temp, Tr = Rated Max Op Temp, Tr>Ta
pV = Cap/Res/Transistor Electrical Stress Factor = e[(Va)/Vr-Va]-2.0
Where Va = Actual Max Operating Voltage, Vr = Abs Max Rated Voltage, Vr>Va
pE = Environmental (Overall) Factor >>>
Indoor Stationary = 1.0
Indoor Mobile = 2.5
Outdoor Stationary = 3.0
Outdoor Mobile = 5.0
Automotive = 7.0
pQ = Quality Factor (Parts and Assembly)
Mil Spec/Range Parts = 0.75
100 Hr Powered Burn In = 0.75
Commercial Parts Mfg Direct = 1.0
Commerical Parts Distributor = 1.25
Hand Assembly Part = 3.0

8. Example: Method A, 0-50C Ambient, Indoor Mobile, Distributor Components
+5VDC
+12VDC
C1 0.1uf 50V
Polyester
C4 0.1uf 50V
Ceramic
+5VDC
LED
Vf=1.5V
R1 2KW 1/4W
Brand A Metal Film
Vin
BPLR
OP AMP
C2 0.1uf 50V
Polyester
5V 1W
Zener
74HCT14
R2 150W 1/4W
Brand B Metal Film
C3 10uf 15V
Electrolytic
-12VDC
Part
Max Tr
Max Vr pT pV pE pQ C1
105C
 50V
 2.082
 0.186
 2.5
 1.25 C2 C3
85C
 15V
 3.773
 0.223 C4
125C
50V 
 1.548
 0.151 R1
120C
20V
 1.643
 0.232 R2
150C 6V
 1.249
 0.549
Zener Diode
100C
N/A
 2.318
1.0
Op Amp
36V
 1.0
74HCT14 7V
 1.649
1.25 
LED  
lFITS
10.29
10.29
552.2
1.46
0.83
1.50
23.18
67.73
217.77
106.16
Fits  Yrs MTBF

9. Block Reliability Estimation Tool

10. Project Reliability Rollup
Initial 90 Day Warranty Period Selected would result in 3% total failures
Consider setting warranty to 1 month or 30 days based on the 1% Total Failure Guideline or …. Decrease l Total

11. Optional Reliability Test Plan
Stress
24 Hour
Model
10 Year Model
Accelerated Stress Model
Accelerated 1 Cycle Time
Acceleration Factor
Max Input Voltage
N/A
Number of Power Cycles
Thermal Range
Number of Therm Cycles
Max Shock Grms
Number of Shock Cycles