Reliability Report

AOS Semiconductor
Product Reliability Report
AO4812/AO4812L,
rev B
Plastic Encapsulated Device
ALPHA & OMEGA Semiconductor, Inc
495 Mercury Drive
Sunnyvale, CA 94085
U.S.
Tel: (408) 830-9742
www.aosmd.com
Feb 16, 2006
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This AOS product reliability report summarizes the qualification result for AO4812. Accelerated
environmental tests are performed on a specific sample size, and then followed by electrical test
at end point. Review of final electrical test result confirms that AO4812 passes AOS quality and
reliability requirements. The released product will be categorized by the process family and be
monitored on a quarterly basis for continuously improving the product quality.
Table of Contents:
I.
II.
III.
IV.
V.
Product Description
Package and Die information
Environmental Stress Test Summary and Result
Reliability Evaluation
Quality Assurance Information
I. Product Description:
The AO4812 uses advanced trench technology to provide excellent RDS(ON) and low gate charge.
The two MOSFETs make a compact and efficient switch and synchronous rectifier combination
for use in buck converters. AO4812 is Pb-free (meets ROHS & Sony 259 specifications).
AO4812L is a Green Product ordering option. AO4812 and AO4812L are electrically identical.
Absolute Maximum Ratings TA=25°C unless otherwise noted
Parameter
Symbol
Maximum
Units
Drain-Source Voltage
VDS
30
V
Gate-Source Voltage
VGS
±20
V
Continuous Drain
Current
TA=25°C
TA=70°C
Pulsed Drain Current
TA=25°C
Power Dissipation
TA=70°C
Junction and Storage
Temperature Range
Thermal Characteristics
Parameter
Maximum Junction-toAmbient
Maximum Junction-toAmbient
Maximum Junction-to-Lead
6.9
ID
5.8
IDM
30
2
PD
W
1.44
TJ, TSTG
-55 to 150
Symbol
t ≤ 10s
SteadyState
SteadyState
A
RθJA
RθJL
°C
Typ
Max
Units
48
62.5
°C/W
74
110
°C/W
35
40
°C/W
2
II. Die / Package Information:
Process
AO4812
AO4812L (Green Compound)
Standard sub-micron
Standard sub-micron
low voltage N channel process low voltage N channel process
Package Type
Lead Frame
Die Attach
Bond wire
Mold Material
Filler % (Spherical/Flake)
Flammability Rating
Backside Metallization
Moisture Level
SOIC-8
Copper with Solder Plate
Ag epoxy
2 mils Au wire
Epoxy resin with silica filler
90/10
UL-94 V-0
Ti / Ni / Ag
Up to Level 1 *
SOIC-8
Copper with Solder Plate
Ag epoxy
2 mils Au wire
Epoxy resin with silica filler
100/0
UL-94 V-0
Ti / Ni / Ag
Up to Level 1*
Note * based on info provided by assembler and mold compound supplier
III. Result of Reliability Stress for AO4812 (Standard) & AO4812L (Green)
Test Item
Test Condition
Time
Point
Solder
Reflow
Precondition
Standard: 1hr PCT+3
cycle [email protected]°c
Green: 168hr 85°c
/85%RH +3 cycle
[email protected]°c
Temp = 150°c ,
Vgs=100% of Vgsmax
0hr
HTGB
HTRB
HAST
Pressure Pot
Temperature
Cycle
Temp = 150°c ,
Vds=80% of Vdsmax
130 +/- 2°c , 85%RH,
33.3 psi, Vgs = 80% of
Vgs max
121°c , 15+/-1 PSIG,
RH=100%
-65°c to 150°c ,
air to air, 0.5hr per cycle
168 / 500
hrs
1000 hrs
168 / 500
hrs
1000 hrs
100 hrs
96 hrs
250 / 500
cycles
Number
of
Failures
0
Lot Attribution
Total
Sample
size
Standard: 49 lots
Green: 16 lots
9625 pcs
17 lots
1394 pcs
(note A*)
77+5 pcs /
lot
17 lots
1394 pcs
(note A*)
77+5 pcs /
lot
Standard: 33 lots
Green: 13 lots
2530 pcs
0
50+5 pcs /
lot
3575 pcs
0
50+5 pcs /
lot
3520 pcs
0
(note B**)
Standard: 49 lots
Green: 16 lots
(note B**)
Standard: 49 lots
Green: 15 lots
(note B**)
0
0
50+5 pcs /
lot
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III. Result of Reliability Stress for AO4812 (Standard) & AO4812L (Green)
Continues
DPA
Internal Vision
Cross-section
X-ray
CSAM
NA
5
5
5
5
5
5
0
NA
5
5
0
Bond Integrity
Room Temp
150°c bake
150°c bake
0hr
250hr
500hr
40
40
40
40 wires
40 wires
40 wires
0
Solderability
230°c
5 sec
15
15 leads
0
Die shear
150°c
0hr
10
10
0
Note A: The HTGB and HTRB reliability data presents total of available AO4812 and AO4812L
burn-in data up to the published date.
Note B: The pressure pot, temperature cycle and HAST reliability data for AO4812 and AO4812L
comes from the AOS generic package qualification data.
IV. Reliability Evaluation
FIT rate (per billion): 1.2
MTTF = 95129years
In general, 500 hrs of HTGB, 150 deg C accelerated stress testing is equivalent to 15 years of
lifetime at 55deg C operating conditions (by applying the Arrhenius equation with an activation
energy of 0.7eV and 60% of upper confidence level on the failure rate calculation). AOS reliability
group also routinely monitors the product reliability up to 1000 hr at and performs the necessary
failure analysis on the units failed for reliability test(s).
The presentation of FIT rate for the individual product reliability is restricted by the actual burn-in
sample size of the selected product (AO4812). Failure Rate Determination is based on JEDEC
Standard JESD 85. FIT means one failure per billion hours.
Failure Rate = Chi2 x 109 / [2 (N) (H) (Af)] = 1.83 x 109 / [ 2 (17×164) (1000) (258) ] = 1.2
MTTF = 109 / FIT = 8.33 x 108hrs = 95129 years
Chi² = Chi Squared Distribution, determined by the number of failures and confidence interval
N = Total Number of units from HTRB and HTGB tests
H = Duration of HTRB/HTGB testing
Af = Acceleration Factor from Test to Use Conditions (Ea = 0.7eV and Tuse = 55°C)
Acceleration Factor [ Af ] = Exp [Ea / k ( 1/Tj u – 1/Tj s )]
Acceleration Factor ratio list:
Af
55 deg C
70 deg C
85 deg C
100 deg C
115 deg C
130 deg C
150 deg C
258
87
32
13
5.64
2.59
1
Tj s = Stressed junction temperature in degree (Kelvin), K = C+273.16
Tj u = The use junction temperature in degree (Kelvin), K = C+273.16
k = Boltzmann’s constant, 8.617164 X 10-5eV / K
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V. Quality Assurance Information
Acceptable Quality Level for outgoing inspection: 0.1% for electrical and visual.
Guaranteed Outgoing Defect Rate: < 25 ppm
Quality Sample Plan: conform to Mil-Std-105D
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