Reliability Report

AOS Semiconductor
Product Reliability Report
AO4900/AO4900L,
rev A
Plastic Encapsulated Device
ALPHA & OMEGA Semiconductor, Inc
495 Mercury Drive
Sunnyvale, CA 94085
U.S.
Tel: (408) 830-9742
www.aosmd.com
Dec 28, 2004
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This AOS product reliability report summarizes the qualification result for AO4900. 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 AO4900passes 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 AO4900 uses advanced trench technology to provide excellent R DS (ON) and low gate charge. The
two MOSFETs make a compact and efficient switch and synchronous rectifier combination for use in
DCDC converters. A Schottky diode is co-packaged in parallel with the synchronous MOSFET to boost
efficiency further. AO4900L (Green Product) is offered in a lead-free package.
Absolute Maximum Ratings T A=25°C unless otherwise noted
Parameter
Symbol
Drain-Source Voltage
VDS
30
V
Gate-Source Voltage
VGS
±12
V
ID
6.9
Continuous
Drain Current
TA=25°C
A
TA=70°C
B
IDM
Pulsed Forward Current B
IFM
TA=25°C
A
TA=70°C
Junction and Storage
Temperature Range
Thermal Characteristics
MOSFET
Maximum Junctiont = 10s
to-Ambient
Maximum JunctionSteadyto-Ambient
State
Maximum JunctionSteadyto-Lead
State
Schottky
Units
5.8
Pulsed Drain Current
Schottky reverse voltage
Continuous
TA=25°C
Forward Current A
TA=70°C
Power
Dissipation
MOSFET
A
40
VKA
30
V
3
IF
2
A
40
PD
TJ , TSTG
Symbol
RθJA
RθJL
2
2
1.44
1.44
-55 to 150
-55 to 150
Typ
Max
48
62.5
74
110
35
40
W
°C
Units
°C/W
2
Thermal Characteristics
Schottky
Maximum JunctionT = 10s
to-Ambient
Maximum JunctionSteadyto-Ambient
State
Maximum JunctionSteadyto-Lead
State
Symbol
RθJA
Typ
Max
47.5
62.5
71
110
32
40
RθJL
Units
°C/W
II. Die / Package Information:
Process
AO4900
AO4900L (Green Compound)
Standard sub-micron
Standard sub-micron
low voltage N channel process low voltage N channel process
Package Type
Lead Frame
Die Attach
Bondwire
Mold Material
Filler % (Spherical/Flake)
Flammability Rating
Backside Metallization
Moisture Level
8 lead SOIC
Copper with Solder Plate
Silver epoxy
2 mils Au wire
Epoxy resin with silica filler
50/50
UL-94 V-0
Ti / Ni / Ag
Up to Level 1 *
8 lead SOIC
Copper with Solder Plate
Silver 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 AO4900 (Standard) & AO4900L (Green)
Test Item
Test Condition
Time Point
Lot Attribution
Total
Sample size
Number of
Failures
Solder
Reflow
Precondition
Normal: 1hr PCT+3
cycle IR reflow@240 ° c
(260° c for Green)
0hr
Normal: 2 lots
Green: 1 lot
495 pcs
0
HTGB
Temp = 150 C,
Vgs=100% of Vgsmax
168 / 500
hrs
Normal: 2 lots
Green: 1 lot
246 pcs
0
1000 hrs
(Note A*)
168 / 500
hrs
Normal: 2 lots
Green: 1 lot
1000 hrs
(Note A*)
77+5 pcs / lot
HTRB
Temp = 150 C, Vds=80%
of Vdsmax
246 pcs
0
77+5 pcs / lot
HAST
Pressure Pot
130 +/- 2 C, 85%, 33.3
psi, Vgs = 80% of Vgs
max
121 C, 15+/-1 PSIG,
RH=100%
100 hrs
Normal: 2 lots
Green: 1 lot
165 pcs
0
50+5 pcs / lot
96 hrs
(Note B**)
Normal: 2 lots
Green: 1 lot
165 pcs
0
50+5 pcs / lot
Temperature
Cycle
-65 to 150 deg C, air to
air, 0.5hr per cycle
250 / 500
cycles
(Note B**)
Normal: 2 lots
Green: 1 lot
165 pcs
0
50+5 pcs / lot
(Note B**)
3
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 AO4900and AO4900L
burn-in data up to the published date.
Note B: The pressure pot, temperature cycle and HAST reliability data for AO4900L comes from
the AOS generic green compound package qualification data.
IV. Reliability Evaluation
FIT rate (per billion): 7.20
MTBF = 15854 years
500 hrs of HTGB, 150 deg C accelerated stress testing is equivalent to 15 years of lifetime at 55
deg 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 (AO4900). Failure Rate Determination is based on JEDEC
Standard JESD 85. FIT means one failure per billion hours.
2
9
Failure Rate = Chi x 10 / [2 (N) (H) (Af)] = 1.83 x 10
9
8
MTBF = 10 / FIT =1.39x 10 hrs = 15854 years
9
/ [2 (492) (1000) (258.24)] = 7.20
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 = 55C)
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 = Boltznan’s constant, 8.617164 X 10E -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
Contacts:
Wei Liu
Engineer of Failure Analysis and Reliability
[email protected]
Fred Chang
Manager of Failure Analysis and Reliability
[email protected]
Wilson Ma
Senior Director of Quality Assurance
[email protected]
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