SiP Module Mold Flowability Experiment Result
and Simulation Study
Presenters:JEONG YongHyuk - STATSChipPAC
April 19, 2018
Agenda
• Project Background & Objectives
• SiP Module information
• Experiment
• Simulation
• Data analysis
• Correlation between simulation and experiment
• Conclusion
Project Background & Purpose
4
Heterogeneous integration of diverse circuit types into a SiP
What is SiP ?
➢ System in Package
▪ Combine dies with different nodes and different
passive components
▪ Advantage in small footprint, Flexibility, Faster time-
to-market, Mixing of technologies and Higher
performance
Problem Statements
5
Complex
& Narrower design
Apple Watch(Source: chipworks)
Narrower component to component
33x33mm PKG, 36 components
Component to Component : Min. 500um
➢ SiP turns to be complex
▪ Increased number of components in a given space
▪ Narrower gap between die-to-passive or passive-to-passive
▪ Narrower clearance between Mold top to components
Purpose
➢ Need to understand molding and its impact
▪ To understand the filling characteristics per density of
components on a substrate
▪ To understand failure modes(Flow behavior, Incomplete fill,
Voids, etc.)
6
Filling characterization with Moldex3D
Potential voids
Incomplete filling
Scope
7
➢ Mold flow ability study
▪ Compare the mold flow ability for different SiP designs by
simulation and experiment
▪ Short shot test was proceeded to visualize the flow and
compare with simulation
▪ Metrologies include visual inspection, X-ray inspection and
scanning acoustic microscopy for void inspection
▪ Failure analysis by X-section and SEM & EDX analysis
8
Project Members
SiP Module Information
SiP Module Information
10
Package type SiP
Package body 9x15mm
Die size 6.6x6.6mm
Die thickness 200 um
Max. PKG total height 1.320 mm
Substrate thickness 4L: 342um
Passive components
3225 Inductor
2016 Inductor
0402 Capacitor
0201 Capacitor
01005 Capacitor
Strip 240 x 95mm
Unit mount 132 units
Single PKG overview
Strip substrate overview
SiP Design
Components Density
11
#1 #2 #3
42% Density 49% Density 65% Density
SiP Design
Mold Clearance
12
Side view
Mold ClearanceClearance
1 25um
2 40um
3 40um(L1,3225) & 225um(L2, 2016)
IC
SiP DesignKeep-Out
13
Inductor
(L1)
3.2mm
0.075mm
Capacitor
0201
0.6mm
0.015mm
Capacitor
0402
1.0mm
0.015mm
Inductor
(L2)
2.0mm
0.025mm
Leg information Gap btw PAD to PAD Gap btw Components to Components
Leg# Item All PADIC Die to Passive
(Die-Inductor / Die –Capacitor)
Inductor to Inductor(L1-L2)
Inductor to Capacitor(L2-0402)
Capacitor to Capacitor(0402-0201)
#1 Narrow 75um 100um / 90um 125um 115um 105um
#2 Mid 100um 125um / 115um 150um 140um 130um
#3 Wide 125um 150um / 140um 175um 165um 155um
Component outline
PAD
IC
0.100mm
0.025mm
0.075mm
0.125mm 0.075mm
0.115mm
0.075mm
0.105mm
Molding Compound
14
4 mold resins are used for Simulation & Experiment
Experiment
DoE Plan
16
Leg# EMC Component Density Mold clearance Keep-out design
*1 #3 42% 20um 100um
*2 #3 49% 20um 100um
*3 #3 65% 20um 100um
4 #3 49% 10um 100um
5 #3 49% 37um 100um
6 #3 65% 20um 75um
7 #3 65% 20um 125um
8 #1 42% 20um 100um
9 #1 49% 20um 100um
10 #1 65% 20um 100um
11 #2 42% 20um 100um
12 #2 49% 20um 100um
13 #2 65% 20um 100um
14 #4 42% 20um 100um
15 #4 49% 20um 100um
16 #4 65% 20um 100um
* Shortshot test was conducted
Experiment Flow
17
Substrate design & fabrication
Solder Paste Printing
SMT
Reflow
Molding
Post Mold Cure
Die attach & Cure
Mold pre-bake & Plasma cleaning
Void inspection by TSAM
Singulation
Void Inspection by CSAM
Data analysis & report
Experiment
18
Sample before molding process
Density Unit image Strip image
42% Density
49% Density
65% Density
19
Mold process
Molding Process (Mold chase design and Flow information)
Flow
direction
Mold Chase design(Total 24 gates & 19EA vent holes)
Strip image before Molding process
1 Pellet diameter 14mm
2 Height 24mm
3 Weight 7g
4 Plunger Diameter 14mm
5 Plunger Height 45mm
6 Plunger Transfer profile setting(Position vs. Speed) See below picture
7 Plunger position vs. time See below picture
8 Transfer pressure vs. time Total time 22.5 sec
Molding process parameter(same as simulation)
Experiment
20
Molding Process(Shortshot test)
42% Density 49% Density 65% Density
30% Fill
50% Fill
80% Fill
Incomplete
filling
Mold Filling Simulation
22
Mold Filling Simulation
Leg# EMCComponent
DensityMold clearance Keep-out design
1 All 4 types 42% 20um 100um
2 All 4 types 49% 20um 100um
3 All 4 types 65% 20um 100um
4 All 4 types 49% 10um 100um
5 All 4 types 49% 37um 100um
6 All 4 types 65% 20um 75um
7 All 4 types 65% 20um 125um
Pellet & plunger set-up
1 Pellet diameter 14mm
2 Height 24mm
3 Weight 7g
4 Plunger Diameter 14mm
5 Plunger Height 45mm
6 Plunger Transfer profile setting(Position vs. Speed) See below picture
7 Plunger position vs. time See below picture
8 Transfer pressure vs. time Total time 22.5 sec
Mold Filling Simulation
Mesh information (1)
#1 #2
#3 #4
25
Mesh information (2)
• Geometry View #5~#7
No. #1 #2 #3 #4 #5 #6 #7
Mesh
count11,439,840 12,510,672 15,629,570 12,510,672 12,362,107 16,084,870 18,07,557
Volume
cc11.48 10.98 9.96 10.97 10.99 9.41 9.96
#5 #6 #7
Venting analysis
• Pressure of air in the filling stage
– Default filling process(assumed fully vacuum in melt
front)
– Enabled venting analysis(the air zone would be
formulated and compressed during filling analysis)
Pair=0
Pair=Pair zone
Venting analysis
• Consider the trapped air behavior and
venting slot effect
H
L
W
Cavity
H,
Vent slot depth
W,
Vent slot width
depthslot vent :H
slot width vent :W
designeron assignedlength slot vent :L
,LH
W123
Qp
Effect of component density
• The higher the component density will lead to
the evident edge flow behavior due to the
unbalanced melt front flow.
Leg# EMCComponent
DensityMold clearance Keep-out design
1 All 4 types 42% 20um 100um
2 All 4 types 49% 20um 100um
3 All 4 types 65% 20um 100um
Simulation of Leg #1
29
voids
• Leg #1
IC
Passive
Die
Simulation of Leg #4
30
voids
• Leg #4
IC
Passive
Die
Data analysis
32
Void inspection(3D X-ray)
• Identify solder voiding under
passive component
• Not clearly identify EMC voiding by
3D X-ray
Metrology
SONOSCAN GEN 6
Location Machine Frequency (MHz) TSAM CSAM depth
A Sonoscan 100 V X
B Sonix 110 V X
C Sonoscan D900 15 V 0.5~1.0㎜ and 0.8~1.2㎜
D Hitachi 50 X NA
E Sonoscan GEN6 50 and 15 X NA
SAT Machine
SAT inspection
Sonix Echo
TSAM Data
34
Voiding analysis by TSAM
Leg# EMC Component Density Mold clearance Keep-out designTSCAN
Voiding %
1 #3 42% 20um 100um 0.0%
2 #3 49% 20um 100um 0.0%
3 #3 65% 20um 100um 0.0%
4 #3 49% 10um 100um 0.0%
2 #3 49% 20um 100um 0.0%
5 #3 49% 37um 100um 0.0%
6 #3 65% 20um 75um 0.0%
3 #3 65% 20um 100um 0.0%
7 #3 65% 20um 125um 0.0%
8 #1 42% 20um 100um 0.0%
9 #1 49% 20um 100um 0.0%
10 #1 65% 20um 100um 0.0%
11 #2 42% 20um 100um 0.0%
12 #2 49% 20um 100um 0.0%
13 #2 65% 20um 100um 0.0%
14 #4 42% 20um 100um 0.0%
15 #4 49% 20um 100um 0.0%
16 #4 65% 20um 100um 0.0%
TSAM Data - Image
35
Void inspection(TSAM)
• No void from TSAM
CSAM Data
36
Void inspection(CSAM)
2
Die
All Die has black spots on the die
X-Sectioning
37
Failure analysis for black spots
Void
Void
X-section line
X-section line
Size: 95.3x168.9um
Size: 72.4x104.3um
SEM & EDX Analysis
38
Failure analysis for black spots
Correlation
Correlation of flow behavior
Simulation Short shot test
42 %
Component
density
49 %
Component
density
65 %
Component
density
Correlation of flow behavior
Without venting analysis Enhanced venting analysisShort shot test
Conclusion
SiP Moldability
43
No visual defect such as incomplete filling with all design and 4 EMCs
Component density is not dominant factor on Moldability
Keep-out design is not dominant factor on Moldability
Mold clearance is not dominant factor on Moldablity
Small black spots are detected for all legs and it is not direct
correlation between SiP design
Black spots might be not used optimized molding process with 4
candidate molding compounds
Well correlation of flow pattern between simulation and experiment
Recommendation
44
No Issue by Current transfer molding techniques when fine filler EMCs
with 82%~87% filler contents are used. However, compression molding
system is required if SiP strip size is bigger and more complicated SiP
design are required.
Viscosity
46
• #1 vs #2 #3 vs #4
#2 has higher viscosity than #1
at temperature = 175 degree C
#3 has higher viscosity than #4
at temperature = 175 degree C
▪ Viscosity at 175’C: #2(higher) > #1 > #3 > #4(lower)
Curing Kinetic Reaction
47
• #1 vs #2 #3 vs #4
#1 has faster curing kinetic than #2
at temperature = 175 degree C
#4 has fastest curing kinetic than #all
at temperature = 175 degree C
▪ Curing kinetic reaction: #4(faster) > #1, #3 > #2(slower)
Pressure-Volume-Temperature-Cure (PVTC) Measurement
• The relationship between isothermal-isobaric volume
shrinkage and the time is expressed as
0
0
0
0
.,h
hh
V
VVCS ii
constTpi
CSi : sample chemical shrinkage at any instant time ti
V0 : sample volume at starting time t0
Vi : sample volume at any instant time ti
h0 : sample height at starting time t0
hi : sample height at any instant time ti
Upper mold
Lower
mold
Lower
mold
plunger
sample
PVTC Measurement
• Kinetic model from DSC can used to transfer (t vs. volume
change) to (Conversion vs. chemical shrinkage)
Ref : A Novel Integrated Warpage Prediction Model Based on Characterization of Viscoelasticity
in Time Domain and Chemical Shrinkage for Molded Underfill, IMPACT 2015
Pressure P1 P2 P3
Volume shrinkage at fully cured
under 175 degree C
1.4% 1.6% 1.8%
PVTC Measurement for different material
50
Note :
Material #1 has lowest shrinkage behavior from the material measurement.
Material name EMC #1 EMC #2 EMC #3 EMC #4
Average filler size(μm) 5 3 3 1
Filler content (wt%) 87 85 82 82
Tg (oC) 135 135 135 135
CTE above Tg (1/oC) 35 45 55 55
CTE below Tg (1/oC) 10 12 14 14
Modulus (GPa) 21 20 17 16
Chemical shrinkage
(%)0.52 0.56 0.64 0.67
EMC #1
EMC #4