Reliability Report

AOS Semiconductor
Product Reliability Report
AO4906/AO4906L,
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 27, 2005
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This AOS product reliability report summarizes the qualification result for AO4906. 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 AO4906passes 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 AO4906 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 DCDC converters. A Schottky diode is co-packaged in parallel with the synchronous
MOSFET to boost efficiency further. Standard Product AO4906 is Pb-free (meets ROHS & Sony
259 specifications). AO4906L is a Green Product ordering option. AO4906 and AO4906L are
electrically identical.
Absolute Maximum Ratings TA=25°C unless otherwise noted
Parameter
Symbol
Mosfet
Schottky
Units
Drain-Source Voltage
VDS
30
V
Gate-Source Voltage
VGS
±12
V
Continuous
Drain Current
TA=25°C
ID
TA=70°C
6
Pulsed Drain Current
IDM
Schottky reverse voltage
VKA
Continuous
Forward Current
TA=25°C
TA=70°C
Pulsed Forward Current
Power
Dissipation
TA=25°C
TA=70°C
Junction and Storage
Temperature Range
7
30
3
IF
2
TJ, TSTG
A
40
IFM
PD
A
40
2
2
1.44
1.44
W
-55 to 150
-55 to 150
°C
2
Thermal Characteristics
MOSFET
Maximum Junctiont ≤ 10s
to-Ambient
Maximum JunctionSteadyto-Ambient
State
Maximum JunctionSteadyto-Lead
State
Thermal Characteristics
Schottky
Maximum Junctiont ≤ 10s
to-Ambient
Maximum JunctionSteadyto-Ambient
State
Maximum JunctionSteadyto-Lead
State
Symbol
Typ
Max
48
62.5
74
110
RθJL
35
40
Symbol
Typ
Max
47.5
62.5
71
110
32
40
RθJA
RθJA
RθJL
Units
°C/W
Units
°C/W
II. Die / Package Information:
Process
AO4906
AO4906L (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
8 lead SOIC
Copper with Solder Plate
Silver epoxy
2 mils Au wire
Epoxy resin with silica filler
90/10
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
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III. Result of Reliability Stress for AO4906 (Standard) & AO4906L (Green)
Test Item
Test Condition
Time Point
Solder
Reflow
Precondition
Standard: 1hr PCT+3
cycle reflow@260°c
Green: 168hr 85°c /85RH
+3 cycle reflow@260 °c
Temp = 150°c,
0hr
HTGB
Vgs=100% of Vgsmax
Lot Attribution
Total
Sample size
Number of
Failures
Standard: 49 lots
Green: 16 lots
9625 pcs
0
168 / 500
hrs
9 lots
738 pcs
0
1000 hrs
(note A*)
168 / 500
hrs
9 lots
1000 hrs
(note A*)
100 hrs
Standard 33 lots
Green: 13 lots
77+5 pcs / lot
HTRB
Temp = 150°c,
Vds=80% of Vdsmax
738 pcs
0
77+5 pcs / lot
HAST
130 +/- 2°c, 85%, 33.3 psi,
Vgs = 80% of Vgs max
2530 pcs
0
50+5 pcs / lot
Pressure Pot
121°c, 15+/-1 PSIG,
RH=100%
96 hrs
(note B**)
Standard: 49 lots
Green: 16 lots
3575 pcs
0
50+5 pcs / lot
Temperature
Cycle
-65°c to 150°c, air to air,
0.5hr per cycle
250 / 500
cycles
(note B**)
Standard: 49 lots
Green: 15 lots
3520 pcs
0
50+5 pcs / lot
(note B**)
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 AO4906and AO4906L
burn-in data up to the published date.
Note B: The pressure pot, temperature cycle and HAST reliability data for AO4906and AO4906L
comes from the AOS generic package qualification data.
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IV. Reliability Evaluation
FIT rate (per billion): 2.5
MTTF = 45662 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 (AO4906). 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 (9×164) (1000) (258)] = 2.5
MTTF = 109 / FIT = 4.0 x 108hrs = 45662 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
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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