AOS Semiconductor Product Reliability Report

AOS Semiconductor
Product Reliability Report
AO4912/AO4912L,
rev B
Plastic Encapsulated Device
ALPHA & OMEGA Semiconductor, Inc
495 Mercury Drive
Sunnyvale, CA 94085
U.S.
Tel: (408) 830-9742
www.aosmd.com
Nov 7, 2005
1
This AOS product reliability report summarizes the qualification result for AO4912. 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 AO4912passes 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 AO4912 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 DC-DC converters. A Schottky diode is co-packaged in parallel with the synchronous
MOSFET to boost efficiency further Standard Product AO4912 is Pb-free (meets ROHS & Sony
259 specifications). AO4912L is a Green Product ordering option. AO4912 and AO4912L are
electrically identical.
Absolute Maximum Ratings TA=25°C unless otherwise noted
Parameter
Symbol
Drain-Source Voltage
Gate-Source Voltage
Continuous
Drain Current
TA=25°C
Max Q2
Units
VDS
30
30
V
VGS
±20
±12
V
ID
8.5
7
6.8
6.4
40
30
2
2
1.28
1.28
W
-55 to 150
-55 to 150
°C
TA=70°C
Pulsed Drain Current
Power
Dissipation
Max Q1
IDM
TA=25°C
TA=70°C
PD
Junction and Storage
Temperature Range
TJ, TSTG
Parameter
Symbol
Reverse Voltage
VDS
Continuous
Forward
Current
TA=25°C
Pulsed Forward Current
Power
Dissipation
IF
TA=70°C
B
TA=25°C
TA=70°C
Junction and Storage
Temperature Range
Maximum Schottky
30
3
A
Units
V
2.2
IFM
PD
TJ, TSTG
20
A
2
1.28
W
-55 to 150
°C
2
Thermal Characteristics
MOSFET Q1
Maximum Junctiont ≤ 10s
to-Ambient
Maximum JunctionSteadyto-Ambient
State
Maximum JunctionSteadyto-Lead
State
Thermal Characteristics
MOSFET Q2
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
48
62.5
74
110
RθJL
35
40
Symbol
Typ
Max
47.5
62.5
71
110
32
40
RθJA
RθJA
RθJA
RθJL
Units
°C/W
Units
°C/W
Units
°C/W
II. Die / Package Information:
Process
AO4912L (Green Compound)
AO4912
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 AO4912 (Standard) & AO4912L (Green)
Test Item
Test Condition
Time Point
Solder
Reflow
Precondition
Standard: 1hr PCT+3
cycle IR [email protected] °c
Green: 168hr 85/85
THB+3 cycle IR
[email protected] °c
0hr
HTGB
Temp = 150°c,
Vgs=100% of Vgsmax
Lot Attribution
Total
Sample size
Number of
Failures
Standard: 49 lots
Green: 16 lots
9625 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 33 lots
Green: 13 lots
77+5 pcs / lot
HTRB
Temp = 150°c,
Vds=80% of Vdsmax
0
82 pcs
77+5 pcs / lot
HAST
130 +/- 2°c, 85%, 33.3 psi,
Vgs = 80% of Vgs max
0
2530 pcs
50+5 pcs / lot
Pressure Pot
121°c, 15+/-1 PSIG,
RH=100%
96 hrs
(note B**)
Standard: 49 lots
Green: 16 lots
0
3575 pcs
50+5 pcs / lot
Temperature
Cycle
-65 to 150°c, air to air,
0.5hr per cycle
250 / 500
cycles
(note B**)
Standard: 49 lots
Green: 15 lots
0
3520 pcs
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 AO4912and AO4912L
burn-in data up to the published date.
Note B: The pressure pot, temperature cycle and HAST reliability data for AO4912and AO4912L
comes from the AOS generic package qualification data.
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IV. Reliability Evaluation
FIT rate (per billion): 21
MTTF = 5436 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 (AO4912). Failure Rate Determination is based on JEDEC
Standard JESD 85. FIT means one failure per billion hours.
2
9
9
Failure Rate = Chi x 10 / [2 (N) (H) (Af)] = 1.83 x 10
9
7
MTTF = 10 / FIT =4.76 x 10 hrs =5436 years
/ [2 (164) (1000) (258)] = 21
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 10E -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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