1
AOS Semiconductor
Product Reliability Report
AO4946/AO4946L, rev A
Plastic Encapsulated Device
ALPHA & OMEGA Semiconductor, Inc
495 Mercury Drive
Sunnyvale, CA 94085
U.S.
Tel: (408) 830-9742 www.aosmd.com
Apr 12, 2007
2
This AOS product reliability report summarizes the qualification result for AO4946. 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 AO4946 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. Product Description
II. Package and Die information
III. Environmental Stress Test Summary and Result
IV. Reliability Evaluation
V. Quality Assurance Information
I. Product Description:
The AO4946 uses advanced trench technology with a monolithically integrated Schottky diode to
provide excellent RDS(ON) and low gate charge. This device is suitable for use as a low and high
side switch in SMPS and general purpose applications. Standard product AO4946 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
TA=25°C 8.6
Continuous Drain
Current TA=70°C IDSM 6.9
Pulsed Drain Current IDM 40
A
Avalanche Current IAR 16
A
Repetitive avalanche energy
L=0.3mH EAR 38
mJ
TA=25°C 2.0
Power Dissipation TA=70°C
PDSM
1.3
W
Junction and Storage
Temperature Range TJ, TSTG -55 to 150 °C
Thermal Characteristics FET1 and FET 2
Parameter Symbol Typ Max Units
Maximum Junction-to-
Ambient T ≤ 10s 48 62.5 °C/W
Maximum Junction-to-
Ambient
Steady-
State
RθJA
74 90 °C/W
Maximum Junction-to-Lead Steady-
State R
θ
JL 32 40 °C/W
3
II. Die / Package Information:
AO4946 AO4946L (Green Compound)
Process Standard sub-micron Standard sub-micron
low voltage N channel process low voltage N channel process
Package Type 8 leads SOIC 8 leads SOIC
Lead Frame Copper with Ag spot Copper with Ag spot
Die Attach Ag epoxy Ag epoxy
Bond wire S：2mils Cu; G: 1.3mils Au S：2mils Cu; G: 1.3mils Au
Mold Material Epoxy resin with silica filler Epoxy resin with silica filler
Filler % (Spherical/Flake) 90/10
100/0
Flammability Rating UL-94 V-0 UL-94 V-0
Backside Metallization Ti / Ni / Ag Ti / Ni / Ag
Moisture Level 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 AO4946 (Standard) & AO4946L (Green)
Test Item Test Condition Time
Point Lot Attribution Total
Sample
size
Number
of
Failures
Solder
Reflow
Precondition
Standard: 1hr PCT+3
cycle reflow@260°c
Green: 168hr 85°c
/85%RH +3 cycle
reflow @260°c
0hr Standard: 83 lots
Green: 29 lots
17380 pcs
0
HTGB
Temp = 150°c ,
Vgs=100% of Vgsmax 168 / 500
hrs
1000 hrs
1 lot
(Note A* )
82 pcs
77+5 pcs /
lot
0
HTRB
Temp = 150°c ,
Vds=80% of Vdsmax 168 / 500
hrs
1000 hrs
1 lot
(Note A* )
82 pcs
77+5 pcs /
lot
0
HAST 130 +/- 2°c , 85%RH,
33.3 psi, Vgs = 80% of
Vgs max
100 hrs Standard: 81 lots
Green: 16 lots
(Note B**)
5335 pcs
50+5 pcs /
lot
0
Pressure Pot 121°c , 29.7 psi ,
100%RH 96 hrs Standard: 83 lots
Green: 20 lots
(Note B**)
5665 pcs
50+5 pcs /
lot
0
Temperature
Cycle -65°c to 150°c ,
air to air 250 / 500
cycles Standard: 87 lots
Green: 29 lots
(Note B**)
6380 pcs
50+5 pcs /
lot
0
4
III. Result of Reliability Stress for AO4946 (Standard) & AO4946L (Green)
Continues
DPA
Internal Vision
Cross-section
X-ray
NA
5
5
5
5
5
5
0
CSAM
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 AO4946 and AO4946L
burn-in data up to the published date.
Note B: The pressure pot, temperature cycle and HAST reliability data for AO4946 and AO4946L
comes from the AOS generic package qualification data.
IV. Reliability Evaluation
FIT rate (per billion): 128
MTTF =891 years
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 (AO4946). 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 = 891 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:
55 deg C 70 deg C 85 deg C 100 deg C 115 deg C 130 deg C 150 deg C
Af 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
5
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
