selecting the right mitigation for bgas and...
TRANSCRIPT
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com© 2004 – 2010
Selecting the Right Mitigation for BGAs and QFNs
DfR Webinar
March 31, 2016
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o Ball grid array (BGA*) and quad flat pack no-lead (QFN)
are increasingly the packaging of choice for most
integrated circuit (IC) devices
Motivation
*Includes chip scale packaging (CSP)
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BGAs: Almost 2/3rd of Semiconductor Packaging Revenue
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QFNs: Most Popular IC Packaging by Volume
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o Thermal Performance
o qja for the QFN is half of leaded counterparts (2X increase in power dissipation)
o Electrical Performance
o Inductance for QFN ishalf of leaded counterparts (no leads, shorter wire bonds)
o Size and Cost
o ‘Poor Man’s BGA’
Why QFNs?
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Why BGAs? The Right Packaging can be Worth $2.5 Billion
www.valuewalk.com/2015/12/apple-iphone-7-a10-chip-solely-tsmc/
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Why Not BGAs and QFNs?
o Greater risk of solder joint failure (thermal cycling,
vibration, mechanical shock)
Cycles to failure
-40 to 125C QFP: >10,000
BGA: 3,000 to 8,000
QFN: 1,000 to 3,000CSP / Flip Chip: <1,000
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o Option 1: Don’t Use Them
o Increasingly not an option
o Option 2: Physics of Failure
o Change the design; predict time to failure
and change the placement, PCB materials,
or housing to meet reliability goals
o Option 3: Underfill/Staking
o Don’t change the design; apply a
polymeric material to reduce strain
on the solder joint
How to Mitigate Risk of QFNs and BGAs
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Background
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o The U.S. Navy and multiple companies funded DfR
Solutions to develop deep expertise in the performance of
Pb-free solders under harsh environments
o Thermal Cycling, Vibration, Mechanical Shock
o Through two SBIRs (Phase I and II)
o Goals
o Develop a methodology to predict vibration and mechanical shock
performance over a range of temperatures (not just 25°C)
o Identify optimum mitigation strategies (corner stake, edge bond,
underfill)
Background
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o Four (4) loading conditions of concern to modern
electronics
o Thermal Cycling (low-cycle fatigue)
o Mechanical Shock / Drop
o Bending (Cyclic or Overstress)
o Vibration (high-cycle fatigue)
Background
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Thermal Cycling Failure Behavior
o Driven by different expansion/contraction behaviors
o Because solder is connecting two materials that are expanding /
contracting at different rates (GLOBAL)
o Because solder is expanding / contracting at a different rate than
the material to which it is connected (LOCAL)
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o This differential expansion and contraction introduces
stress into the solder joint
o This stress causes the solder to deform (aka, elastic and plastic
strain)
o The extent of this strain
(that is, strain range or
strain energy) tells us the
lifetime of the solder joint
o The higher the strain, the
more the solder joint is damaged,
the shorter the lifetime
Thermal Cycling Failure Behavior (cont.)
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o Low cycle fatigue (LCF) is driven by inelastic strain (Coffin-Manson)
o Difficult to provide predictions under 100 events/cycles
o Considered relevant out to 10,000 cycles
o High cycle fatigue (HCF) is driven by elastic strain (Basquin)
o Primarily vibration, but can be bending as well
o Failures above 100,000 cycles
Mechanical Cycling (Shock, Bending, Vibration)
b
f
f
e NE
2
-0.05 < b < -0.12; 8 < -1/b < 20
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Option 2: Physics of Failure
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o Knowing the critical drivers for solder joint fatigue, we can
develop predictive models and design rules
Drivers for Solder Joint Thermo-Mechanical Failures
CTE of Board
Elastic Modulus (Compliance) of Board
CTE of Component
Elastic Modulus (Compliance) of Component
Length of Component
Volume of Solder
Thickness of Solder
Solder Fatigue Properties
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Predictive Models – Physics of Failure (PoF)
o Modified Engelmaier for Pb-free Solder (SAC305)
o Semi-empirical analytical approach
o Energy based fatigue
o Determine the strain range (Dg)
o C is a correction factor that is a function of dwell time and
temperature, LD is diagonal distance, a is coefficient of
thermal expansion (CTE), DT is temperature cycle, h is
solder joint height
Th
LC
s
D DDD ag
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Predictive Models – Physics of Failure (PoF)(cont.)
o Determine the shear force applied to the solder joint
o F is shear force, L is length, E is elastic modulus, A is the area, h
is thickness, G is shear modulus, and a is edge length of bond pad
o Subscripts: 1 is component, 2 is board, s is solder joint, c is bond
pad, and b is board
o Takes into consideration foundation stiffness and both
shear and axial loads
D
aGGA
h
GA
h
AE
L
AE
LFLT
bcc
c
ss
s
9
2
221112
aa
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Predictive Models – Physics of Failure (PoF)(cont.)
o Determine the strain energy dissipated by the
solder joint
o Calculate cycles-to-failure (N50), using energy
based fatigue models
10019.0
D WN f
sA
FW DD g5.0
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Validation of Physics of Failure (Thermal Cycling)
BGA
QFN
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o “The Sherlock analysis that DfR solutions did last year predicted
that the QFN would fail first during thermal cycling <sic>. At the
time last year we did not agree with what Sherlock was telling us,
but after lots of $$$ and thermal cycles, Sherlock was right.
It was a very important lesson learned about thermal cycling life
of large QFN packages on boards that are epoxy laminated to
aluminum chassis<sic>. This is something that we would not have
guessed to be a problem. But it was.
Sherlock now has added merit for us to consider using on other
new product reliability analyses”
- John DeCamp, Manufacturing Engineer
Validation – ViaSat
21
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o “Following discussions with DfR and confirmation of the PCB material, from the supplier, I was able to refine the model for the QFN package and the PCB construction to predict the first failure of a QFN package at around 700 cycles.
It was interesting to note that the PCB material choice significantly altered Sherlock’s predicted solder joint life and choice of PCB material needs to be carefully considered from this perspective.
Subsequent real cycling of the test board has indeed produced a failure at around 770 temperature cycles and so appearing to add some (albeit limited) validation of the Sherlock prediction.
With the refined model failures of well soldered BGA joints were not predicted by Sherlock till around 3000 cycles. Our supplier has now finished the thermal cycles on the real boards seeing no BGA failures after about 1200 cycles.”
Validation – Rolls Royce
22
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Influence of PCB Properties
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o During vibration, board-level strain is
proportional to solder or lead strains
and therefore can be used to make
time-to-failure predictions
o Requires converting
cycles-to-failure displacement
equations (Steinberg) to use strain
o The critical strain for the package
types is a function of package style,
size, lead geometry
High Cycle Fatigue (Prediction)
n
ccNN
0
0
Lcc
ζ is analogous to 0.00022B but
modified for strain
c is a component packaging function
L is component length
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o Incorporate a 2x safety factor per Steinberg (f reduced by 50%)
Validation of Physics of Failure (Vibration)
Cycles to
Failure
SAC305SnPbSolder Alloy
4.6
116
fN
8.7
71
fN
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o Step 1: Implement in Component Engineering
o Each new request to add a part to the approved vendors list (AVL) should be assessed for risk of solder joint failure (ie, all QFNs and BGAs)
o Step 2: Benchmark PoF Prediction
o Run a PoF simulation and compare to supplier’s test data
o If no test data, identify reliability by similarity (RBS) equivalent
o If RBS, decide to either test or move forward with PoF only
o Step 3: Perform PoF before Layout
o After layout is too late to change the design (stackup, bond pad sizing, stencil thickness, placement, attachments, etc.)
Developing a PoF Process
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Option 3: Underfill/Staking
(Thermal Cycle Mitigation)
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o Underfill has been used since to mitigate flip chip solder
risk since the late 1980’s
o Up to two orders of magnitude improvement in lifetime
o Has led to interest in mitigating thermal cycling risks with
BGAs
o However, far less substantive research on the influence of underfill
and thermo-mechanical fatigue of 2nd level interconnects
o General trends can be identified through review of
published work and the use of physics of failure (PoF)
Thermal Cycle Mitigation: BGA
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o BGA
o 12.5MM X 12.5MM X 1.2MM
o 900 Solder Balls (0.4mm pitch, 0.25mm dia., 0.11mm height)
o Die size 8MM X 8MM
o Thermal Cycle
o 15C to 85 C, 10 Hours cycle
o PCB
o CTE of 15.8 ppm/°C
o Modulus of 44 GPa
Step 1: PoF-Based Simulation on BGA with No Underfill
Sherlock predicts a
lifetime of 1500 cycles
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o Glass Transition Temperature (Tg) of 102°C
o Coefficient of Thermal Expansion (CTE) of 55 ppm/°C
o Elastic Modulus (E) is 3 GPa
Step 2: Adjust PoF Prediction Based on Underfill Properties
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o Tg has limited influence as long as it is greater than
maximum temperature during thermal cycling
o Derived approach
o Assumed adjustment factor
is 1 for Tg above 100°C
and 0.1 for Tg at 25C
o Assume a logarithmic
response to change in Tg
o Based on thermal cycle
of 0 to 100C
Tg and Life Adjustment Factor
y = 0.6ln(x) - 1.8
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140
Fati
gue
Life
Co
rrec
tio
n F
acto
r
Tg in Degrees Celsius
Tg Fatigue Correction Factor
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o Underfill CTE is almost always greater than 20 ppm/°C
CTE and Life Adjustment Factor
Figure 8 From “A Parametric Study of Flip Chip Reliability Based on Solder
Fatigue Modelling: Part II - Flip Chip on Organic” by Scott F. Popelar
y = 9000x-2
1
10
100
1000
10000
0 10 20 30 40 50 60
Fati
gue
Lif
e C
orr
ect
ion
Fac
tor
Underfill CTE (ppm/C)
CTE Fatigue Life Correction
Model doesn’t work for values below CTE of solder
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o Since most underfill have modulus close or near 2 GPa
the fatigue life correction factor at 2 is set to near 1
Modulus and Life Adjustment Factor
Figure 7 From “A Parametric Study of Flip Chip Reliability Based on Solder
Fatigue Modelling: Part II - Flip Chip on Organic” by Scott F. Popelar
Model doesn’t work for values below 2
y = e-0.05x
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 5 10 15 20
Fatigue
Lif
e C
orr
ect
ion
Fact
or
Modulus (GPa)
Modulus Fatigue Life Correction
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o Maximum temperature of 85°C below Tg of 102C
o CTE is relatively high 55 ppm/ C
o Modulus is nominal 3 GPa
o Prediction formula (not PoF-based)
𝑒−0.05𝐸 × 9000g−2 × 0.6 ln 𝑇𝑔 − 1.8Where
E = modulus in GPa
g = CTE in ppm/ C
Tg = Glass Transition Temperature in C
Life Adjustment Factor
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o Predicted life increase using underfill is 2.5X
o Sherlock Prediction (no underfill): 1500 cycles
o Prediction with Adjustment Factor (underfill): 3750 cycles
Life Adjustment Factor: Results
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o Underfill is not always the best optiono Expensive
o Time-consuming
o Low throughput
o Increasing interest in the use of edge bonding to provide a similar degree of protectiono Or, at the very least, not to reduce time to
failure (if edge bond is used for vibration or shock mitigation)
o Evaluated through thermal cycle testingo -55C to +125C (thermal cycle), 15 min dwells,
1000 cycles
o Mid-size BGAs (256 and 288 I/O)
Thermal Cycle Mitigation: Edge Bonding
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o Minimal to no improvement [66 ppm/C, Two Tgs (-39 and 77)]
0%
20%
40%
60%
80%
100%
120%
0 200 400 600 800 1000
thermal cycles
cu
mu
lati
ve f
ail
ure
Choc. Chip, Scotchweld 2214
Edge Bond, EMAX 904-GEL
Edge Bond, Loctite 3128
Edge Bond, Loctite 3705
Edge Bond, Namics 1583-2
Edge Bond, Scotchweld 2214
Edge Bond, Zymet UA-2605
As Manufactured
A-CABGA56-.5mm-6mm-DC
A-CABGA288-.8mm-19mm-DC
A-CABGA256-1.0mm-17mm-DC
no underfilled parts failed
B Edge Bond (not reworkable)
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C Edge Bond
o Minimal to no improvement [40 ppm/C, Tg of 45C]
0%
20%
40%
60%
80%
100%
120%
0 200 400 600 800 1000
thermal cycles
cu
mu
lati
ve f
ail
ure
Choc. Chip, Scotchweld 2214
Edge Bond, EMAX 904-GEL
Edge Bond, Loctite 3128
Edge Bond, Loctite 3705
Edge Bond, Namics 1583-2
Edge Bond, Scotchweld 2214
Edge Bond, Zymet UA-2605
As Manufactured
A-CABGA56-.5mm-6mm-DC
A-CABGA288-.8mm-19mm-DC
A-CABGA256-1.0mm-17mm-DC
no underfilled parts failed
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D Edge Bond
o 50% improvement [23 ppm/C, Tg of 80C]
0%
20%
40%
60%
80%
100%
120%
0 200 400 600 800 1000
thermal cycles
cu
mu
lati
ve f
ail
ure
Choc. Chip, Scotchweld 2214
Edge Bond, EMAX 904-GEL
Edge Bond, Loctite 3128
Edge Bond, Loctite 3705
Edge Bond, Namics 1583-2
Edge Bond, Scotchweld 2214
Edge Bond, Zymet UA-2605
As Manufactured
A-CABGA56-.5mm-6mm-DC
A-CABGA288-.8mm-19mm-DC
A-CABGA256-1.0mm-17mm-DC
no underfilled parts failed
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0%
20%
40%
60%
80%
100%
120%
0 200 400 600 800 1000
thermal cycles
cu
mu
lati
ve f
ail
ure
Choc. Chip, Scotchweld 2214
Edge Bond, EMAX 904-GEL
Edge Bond, Loctite 3128
Edge Bond, Loctite 3705
Edge Bond, Namics 1583-2
Edge Bond, Scotchweld 2214
Edge Bond, Zymet UA-2605
As Manufactured
A-CABGA56-.5mm-6mm-DC
A-CABGA288-.8mm-19mm-DC
A-CABGA256-1.0mm-17mm-DC
no underfilled parts failed
A Edge Bond (Reworkable)
o Substantial improvement [30 ppm/C, Tg of 90C]
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o The lower the CTE and the higher the Tg, the better the
mitigation
o Smaller BGAs may be at some risk of reduced time to
failure
o 6mm BGA (not shown in graphs) failed slightly faster with edge
bonding
o Staking can potential provide the necessary mitigation at
substantially lower cost and higher throughput
Thermal Cycle Migitation (Underfill/Staking): Conclusion
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Option 2: Underfill/Staking
(Vibration/Shock Mitigation)
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o SBIR:
Assess vibration and shock performance over a range of
temperatures
o SBIR Consortium:
Identify optimum mitigation strategies for vibration and
mechanical shock (corner stake, edge bond, underfill)
Research Focus
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SBIR: Experimental Setup, Parts
Package Style Package Type Pitch Manufacturer
Chip Component 1206 0W resistor N/A Panasonic
Chip Component 2512 0W resistor N/A Stackpole
Chip Component 1812 120W ferrite bead N/A TDK
C-Lead SMC 3126 C-Lead Schottky Diode N/A Fairchild
CSP (chip scale package) CSP97 (CVBGA97) 0.4 Practical
Mid-Size BGA (ball grid array) BGA484 (PBGA484) 1.0 Practical
Large BGA (ball grid array) BGA1156 (PBGA1156) 1.0 Practical
TSOP Type I (thin small-outline package) TSOP48, Type I 0.5 Topline Electronics
TSOP Type II (thin small-outline package) TSOP54, Type II 0.8 Topline Electronics
QFP (quad flat pack) QFP100 0.5 Practical
QFN (quad-flat no-leads) QFN68 0.5 Practical
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o Mechanical Shock at 125°C
was implemented through the
use of in-board heating traces
o Mechanical Shock at -55°C
was implemented through
the use of an insulated
box attached to the drop
plate
SBIR: Experimental Setup, Environments (cont.)
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o Because extensive sinusoidal vibration testing was
performed on a range of components in SBIR Phase I,
Sinusoidal Vibration was limited to one displacement
condition
o Sinusoidal Vibration model developed and validated
o Executed on a modified Unholtz-Dickie
SBIR: Experimental Setup, Environments (cont.)
Condition Displacment Frequency* Temperature (°C)
1 90 mils 160-165 Hz 25
2 90 mils 160-165 Hz 125
3 90 mils 160-165 Hz (-55)
*5 to 10Hz below natural frequency
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o Frequency range was adjusted to account for board response and the tendency of the component to fail under vibration
o PSD curve was applied for 80 Hz above and 80 Hz below the natural frequency of the board
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BGA484 and BGA1156: Experimental Design
Test Temp Stress Level Finish Solder Alloys
Shock 25°C 550G ENIG SnPb, SAC305, SAC105
Shock 25°C 550G OSP SnPb, SAC305, SAC105
Shock 25°C 900G ENIG SnPb, SAC305, SAC105
Shock 25°C 900G OSP SnPb, SAC305, SAC105
Shock 25°C 1500G ENIG SnPb, SAC305, SAC105
Shock 25°C 1500G OSP SnPb, SAC305, SAC105
Random 25°C 0.1G2/Hz OSP SAC105
Random 125°C 0.1G2/Hz OSP SnPb, SAC305, SAC105
Random (-55)°C 0.1G2/Hz OSP SnPb, SAC305, SAC105
Random 25-125°C 0.1G2/Hz OSP SnPb, SAC305, SAC105
Test Temp Stress Level Finish Solder Alloys
Shock 25°C 750G ENIG SnPb, SAC305, SAC105
Shock 25°C 750G OSP SnPb, SAC305, SAC105
Shock 25°C 1500G ENIG SnPb, SAC305, SAC105
Shock 25°C 1500G OSP SnPb, SAC305, SAC105
Shock 25°C 2500G ENIG SnPb, SAC305, SAC105
Shock 25°C 2500G OSP SnPb, SAC305, SAC105
Shock 125°C 2500G ENIG SnPb, SAC305, SAC105
Shock 125°C 2500G OSP SnPb, SAC305, SAC105
Shock (-55)°C 2500G ENIG SnPb, SAC305, SAC105
Shock (-55)°C 2500G OSP SnPb, SAC305, SAC105
Sinusoidal 25°C 90mils OSP SAC105
Sinusoidal 125°C 90mils OSP SAC105
Sinusoidal (-55)°C 90mils OSP SAC105
Random 25°C 0.1G2/Hz OSP SnPb, SAC305, SAC105
Random 125°C 0.1G2/Hz OSP SnPb, SAC305, SAC105
Random (-55)°C 0.1G2/Hz OSP SnPb, SAC305, SAC105
Crack Initiation (-55)°C – 125°C ENIG SnPb, SAC305, SAC105
Crack Initiation (-55)°C – 125°C OSP SnPb, SAC305, SAC105
Crack Initiation 25°C – 125°C ENIG SnPb, SAC305, SAC105
Crack Initiation 25°C – 125°C OSP SnPb, SAC305, SAC105
BGA484 BGA1156
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o All failures were solder joint failures
o Identified very clear trends in regards to solder alloy and
temperature
BGA484 and BGA1156: Mechanical Shock
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o SAC105 and SAC305 show strong sensitivity to temperature
o Minimal difference between OSP / ENIG
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o SnPb solder clearly superior, even at room temperature,
to SAC105 and SAC305 at high strain rates
o Minimal difference between OSP and ENIG
BGA 1156: Mechanical Shock
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o A temperature dependent failure trend can be seen, with hotter temperatures failing first. o At higher temperatures the crack propagates through the bulk solder, while
at lower temperatures it propagates along the IMC.
BGA484: Sinusoidal Vibration
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o Able to create design curve from test results from SBIR
Phase I and mechanical shock and vibration test results
BGA484 and BGA1156: Design Curves
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o Components ‘generally’ behaved as expected
o Either already known or explained based on mechanical response
or material behavior
o Allows for the development of a vibration as a function of
temperature capability in Sherlock
o Lower stresses tends to reduce differentiation among
solder alloys
o True for both mechanical shock and vibration
Overall Trends
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
o Edge bond/Corner Stake: Zymet & Namics
o Underfill: Loctite & Namics
Experimental Design – Mitigation (BGA208)
Corner Stake Edge Bond Underfill
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
o Mechanical Shock:
o 1500G, 0.5 millisecond pulse
o -55C, 25C, 125C
o Sinusoidal Vibration
o 90 mils displacement
o Situated 5-10 Hz below natural frequency
Experimental Design
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Shock/Drop and Corner StakingReliaSoft Weibull++ 7 - www.ReliaSoft.com
Probability - Weibull
Corner Stake BGA\1583: Corner Stake BGA\UA 2605: Corner Stake BGA\SnPb: Corner Stake BGA\SN100C: Corner Stake BGA\SAC:
Number of Drops
Un
reli
ab
ilit
y,
F(
t)
10.000 1000.000100.0001.000
5.000
10.000
50.000
90.000
99.000
x 4
Probability-Weibull
Corner Stake BGA\SACWeibull-2PRRX SRM MED FMF=12/S=3
Data PointsProbability L ine
Corner Stake BGA\SN100CWeibull-2PRRX SRM MED FMF=10/S=5
Data PointsProbability L ine
Corner Stake BGA\SnPbWeibull-2PRRX SRM MED FMF=10/S=5
Data PointsProbability L ine
Corner Stake BGA\UA 2605Weibull-2PRRX SRM MED FMF=4/S=11
Data PointsProbability L ine
Corner Stake BGA\1583Weibull-2PRRX SRM MED FMF=6/S=9
Data PointsProbability L ine
Melissa KeenerDfR Solutions8/7/20123:55:11 PM
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Shock/Drop and Edge BondingReliaSoft Weibull++ 7 - www.ReliaSoft.com
Probability - Weibull
Edge Bond BGA\1583: Edge Bond BGA\VA2605: Edge Bond BGA\SN100C: Edge Bond BGA\SnPb: Edge Bond BGA\SAC:
Number of Drops
Un
reli
ab
ilit
y,
F(
t)
10.000 1000.000100.0001.000
5.000
10.000
50.000
90.000
99.000
x 4
Probability-Weibull
Edge Bond BGA\SACWeibull-2PRRX SRM MED FMF=12/S=3
Data PointsProbability L ine
Edge Bond BGA\SnPbWeibull-2PRRX SRM MED FMF=10/S=5
Data PointsProbability L ine
Edge Bond BGA\SN100CWeibull-2PRRX SRM MED FMF=10/S=5
Data PointsProbability L ine
Edge Bond BGA\VA2605Weibull-2PRRX SRM MED FMF=7/S=8
Data PointsProbability L ine
Edge Bond BGA\1583Weibull-2PRRX SRM MED FMF=6/S=9
Data PointsProbability L ine
Melissa KeenerDfR Solutions8/14/20123:57:00 PM
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Shock/Drop and UnderfillReliaSoft Weibull++ 7 - www.ReliaSoft.com
Probability - Weibull
Underfill\BGA L3549: Underfill\SN100C: Underfill\SnPb: Underfill\SAC305:
Number of Drops
Un
reli
ab
ilit
y,
F(
t)
10.000 1000.000100.0001.000
5.000
10.000
50.000
90.000
99.000
x 4
x 15
Probability-Weibull
Underfill\SAC305Weibull-2PRRX SRM MED FMF=12/S=3
Data PointsProbability L ine
Underfill\SnPbWeibull-2PRRX SRM MED FMF=10/S=5
Data PointsProbability L ine
Underfill\SN100CWeibull-2PRRX SRM MED FMF=10/S=5
Data PointsProbability L ine
Underfill\BGA L3549Weibull-1PMLE SRM MED FMF=0/S=15
Susp PointsProbability L ine
Melissa KeenerDfR Solutions8/31/201211:20:58 AM
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Mitigation Technique Mitigation Material Benefit
Corner StakingA 3 times better than baseline
C 2 times better than baseline
Edge BondingA 10 times better than baseline
C 2 times better than baseline
UnderfillB No failures during testing
D 10 times better than baseline
Effect of Mitigation: Mechanical Shock
Mitigation Technique Mitigation Material Benefit
Corner StakingA 100 times better than baseline
C No change from baseline
Edge BondingA 100 times better than baseline
C 100 times better than baseline
UnderfillB 10 times better than baseline
D >100 times better than baseline
Mitigation Technique Mitigation Material Benefit
Corner StakingA No change from baseline
C No change from baseline
Edge BondingA 5 times better than baseline
C 5 times better than baseline
UnderfillB 10 times better than baseline
D 3 times better than baseline
-55C
25C
125C
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Mitigation Technique Mitigation Material Benefit
Corner StakingA No change from baseline
C No change from baseline
Edge BondingA 30 times better than baseline
C No change from baseline
UnderfillB No failures during testing
D 80 times better than baseline
Effect of Mitigation: Sinusoidal Vibration
Mitigation Technique Mitigation Material Benefit
Corner StakingA No failures during test
C No change from baseline
Edge BondingA No failures during test
C No failures during test
UnderfillB 35 times better than baseline
D No failures during test
Mitigation Technique Mitigation Material Benefit
Corner StakingA 20 times worse than baseline
C 20 times worse than baseline
Edge BondingA No change from baseline
C 40 times worse than baseline
UnderfillB No change from baseline
D One failure during testing
-55C
25C
125C
© 2004 - 2007© 2004 - 20109000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
o The value of mitigation can be quantified
o Sherlock now offers coating/potting/staking module
o Simple design solutions (underfill everything) can be
evaluated against simple manufacturing solutions (change
stackup, bond pads)
o Sometimes less is more
o Sometimes less is not enough!
Conclusion
Coating/Potting