SiP Module Mold Flowability Experiment Result and ...

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


Leg# EMCComponent

DensityMold clearance Keep-out design

1 All 4 types 42% 20um 100um







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


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




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


▪ 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


#4 has fastest curing kinetic than #all


▪ 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

SiP Module Mold Flowability Experiment Result and ...

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