Reliability Report

AOS Semiconductor
Product Reliability Report
AO4800B/AO4800BL,
rev A
Plastic Encapsulated Device
ALPHA & OMEGA Semiconductor, Inc
495 Mercury Drive
Sunnyvale, CA 94085
U.S.
Tel: (408) 830-9742
www.aosmd.com
Oct 15, 2007
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This AOS product reliability report summarizes the qualification result for AO4800B. 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 AO4800B 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.
I.
Product Description
Package and Die information
Environmental Stress Test Summary and Result
Reliability Evaluation
Quality Assurance Information
Product Description:
The AO4800B 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. Standard Product AO4800B is Pb-free (meets ROHS & Sony 259
specifications).
Absolute Maximum Ratings TA=25°C unless otherwise noted
Parameter
Symbol
Maximum
Units
Drain-Source Voltage
VDS
30
V
Gate-Source Voltage
VGS
±12
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
40
1.9
PD
W
1.2
TJ, TSTG
-55 to 150
Symbol
T ≤ 10s
SteadyState
SteadyState
A
RθJA
RθJL
°C
Typ
Max
Units
55
62.5
°C/W
90
110
°C/W
40
48
°C/W
2
II. Die / Package Information:
AO4800B
Process
Package Type
Lead Frame
Die Attach
Bond wire
Mold Material
Filler % (Spherical/Flake)
Flammability Rating
Backside Metallization
Moisture Level
AO4800BL (Green Compound)
Standard sub-micron
Standard sub-micron
Low voltage N channel process Low voltage N channel process
8 leads SOIC
8 leads SOIC
Copper with Ag spot
Copper with Ag spot
Ag epoxy
Ag epoxy
S: Cu 2mils; G: Au 1.3mils
S: Cu 2mils; G: Au 1.3mils
Epoxy resin with silica filler
Epoxy resin with silica filler
90/10
100/0
UL-94 V-0
UL-94 V-0
Ti / Ni / Ag
Ti / Ni / Ag
Up to Level 1 *
Up to Level 1*
Note * based on info provided by assembler and mold compound supplier
III. Result of Reliability Stress for AO4800B (Standard) & AO4800BL (Green)
Number
of
Failures
Test Item
Test Condition
Time
Point
Lot Attribution
Total
Sample
size
Solder
Reflow
Precondition
Standard: 1hr PCT+3
cycle reflow@260°c
Green: 168hr 85°c
/85%RH +3 cycle
reflow@260°c
Temp = 150°c ,
Vgs=100% of Vgsmax
0hr
Standard: 7 lots
770 pcs
0
168 / 500
hrs
1 lot
82 pcs
0
1000 hrs
(Note A*)
168 / 500
hrs
1 lot
1000 hrs
(Note A*)
100 hrs
Standard: 3 lots
165 pcs
0
96 hrs
(Note B**)
Standard: 4 lots
50+5 pcs /
lot
220 pcs
0
50+5 pcs /
lot
385 pcs
0
HTGB
HTRB
HAST
Pressure Pot
Temp = 150°c ,
Vds=80% of Vdsmax
130 +/- 2°c , 85%RH,
33.3 psi, Vgs = 80% of
Vgs max
121°c , 29.7psi,
100%RH
(Note B**)
Temperature
Cycle
-65°c to 150°c ,
air to air
250 / 500
cycles
Standard: 7 lots
(Note B**)
77+5 pcs /
lot
82 pcs
0
77+5 pcs /
lot
50+5 pcs /
lot
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III. Result of Reliability Stress for AO4800B (Standard) & AO4800BL (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
245°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 AO4800B and
AO4800BL burn-in data up to the published date.
Note B: The pressure pot, temperature cycle and HAST reliability data for AO4800B and
AO4800BL comes from the AOS generic package qualification data.
IV. Reliability Evaluation
FIT rate (per billion):128
MTTF = 891years
In general, 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 (AO4800B). 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 (164) (168) (258)] = 128
MTTF = 109 / FIT = 7.81 x 106hrs =891years
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
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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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