TI OMAP4430 POP SMT Design Guideline

SWPA182B
TI OMAP4xxx POP SMT
Design Guideline
Michael Chen (TITL PKG)
Kenji Masumoto (HIJI PKG)
Shawn Wu (TITL PKG)
Kurt Wachtler (WTBU PKG)
We Support
1
Agenda:
X Package Introduction
X OMAP4 SMT Process sharing
9Stencil/PCB design guide
9Memory chip flux/solder dipping in 1-step mounting
9The example of Pick & Place machine condition setting
9Reflow profile recommendation
9SMT experiment examples
X Q& A
2
OMAP4XXX POP Packages
Memory
OMAP 4
System Board
3
Mechanical Drawing of OMAP4xxx CBS (TMV)
OMAP4xxx
Top View
Bottom View
4
OMAP4xxx TMV
A-Dimension
D2
D3
5
Mechanical Drawing of Memory Chip
Memory Chip
Bottom View
6
Agenda:
X Package Introduction
X OMAP4 SMT Process sharing
9Stencil/PCB design guide
9Memory chip flux/solder dipping in 1-step mounting
9The example of Pick & Place machine condition setting
9Reflow profile recommendation
9SMT experiment examples
X Q& A
7
Stencil/PCB design guide for P0.4 OMAP4
PWB Land & Stencil aperture design Recommendation for pitch 0.4mm
Solder Mask Defined
SMD
PWB Design
A
B
Ball Pitch
Stencil Design
Thickness Opening
B
SMD*
0.4mm
A
NSMD
Non Solder Mask Defined
0.23 0.28 0.08/0.1 0.25
0.08/0.1 0.20
(Zone C)
0.28 0.23 0.08/0.1 0.25
0.08/0.1 0.20
(Zone C)
(Zone A+B)
(Zone A+B)
NSMD
B
• Avoid VIP( Via in Pad) design. If should do it, the plugged via
with flatten surface is recommended.
A
Zone C
Zone B
Zone A
• SMD design is more suggested than NSMD to prevent the
solder starvation form trace neck or irregular joint shape.
• Trace design: No big ground with several pads connection or
wide trace neck.
• Square opening of Stencil can get more volume for joint print.
8
Package on Package (POP)
Surface Mount Assembly Process Flow
• Screen print solder paste to PCB
• Pick and place OMAP BGA
OMAP
PCB
• Dip Memory package into flux or paste
• Place on top of OMAP package
Memory
Flux Dip Station
Memory
OMAP
PCB
• Reflow to form POP stack
9
Memory chip flux/solder dipping
recommendation in 1-step mounting
“A” memory DC package, is dipped into flux with variable depth
Memory Chip
Ball height
Variable depth of flux
e.g. 20% dipping
e.g. 50% dipping
Ball height
50% depth
66%
50%
50% is appropriate
dipping depth
Flux/solder past dip depth:
From the evaluation, the optimal results at 50-70 % flux dip and solder paste.
10
Flux/Solder Paste Depth Measurement
Gauge of height measurement
Flux/paste dipping depth was
measured by using height gauge
shown in below picture.
Flux/Paste Dipping feeder
Roll & measure
Good dip sample
Bad dip sample
Flux or Paste
The dipping performance contributed the top level soldering yield directly.
11
Measurement of flux depth (Example)
12
Condition of PnP M/C setting (example)
Placement Parameters:
Panasonic NPM
9SMT M/C Brand: Panasonic
9Type: NPM
Next Production Modular
9Device Placement: OMAP4 + Memory Chip
9Placement method: By 1-step
9Fiducial marks recognition for placement:
By Board fiducial
9Pick up Nozzle type: 1004
9Nozzle size: ~8mm (with robber tip)
9Memory Vision sequence: Pickup + Camera
vision + Memory Dipping + Placement
9Dwell time of memory dipping: 400ms ~1 sec
9Placement Force (N) or placement depth (um):
For OMAP4: package height+1~2.5N (push down)
For Memory Chip: package height+1~2.5N (push down)
Nozzle type: 1004
13
Bottom and Top BGA Placement
Surface Mounter: Fuji NXT
Memory Package
Flux Dipping Reservoir
Ideal Flux Depth = 50-60%
14
Temperature – Degrees C
Profile Recommendation for OMAP4xxx (TMV)
250
200
150
100
50
Preheating Stage
Reflow Cool Down
Time
Reflow conditions:
¾ RT to 150°C
¾ Pre –heat temp(150~200 °C)
¾ Time above melting 220°C
¾Peak temp
¾ Cool down rate
1~3°C/s
60~120sec
50~80sec
240-250°C
2~6°C/sec (max.)
9 Evaluated solder paste:
9 Shenmao PF-606-P (SAC305)
9 Tamura TLF-204-19A
9 Evaluated Memory dip flux/paste:
9 Senju M705-TVA03.9F (Paste)
9 Senju Deltalux-901K3 (Flux)
9 <700 ppm O2 reflow atmosphere is recommended to
provide the widest process window.
9 The real profile must be fine-tuned for each product to
meet the optimized soldering results
15
PCB panel
16
POP profile test board example
3
2
1
b.
-Thermal couple test locations: see above picture
-Thermal couple test points:
a. The central point btw PCB & OMAP
b. The central point btw OMAP & Memory
-Total 6 test points
a.
17
2-pass reflow: Pre-stack tray for FCPOP
To check temperature profile
Pre-stack tray designed for TI OMAP3430
Bottom POP is supported by
this rib to depopulated ball area
Pre-stack tray designed for TI OMAP3430
18
Agenda:
X Package Introduction
X OMAP4 SMT Process sharing
9Stencil/PCB design guide
9Memory chip flux/solder dipping in 1-step mounting
9The example of Pick & Place machine condition setting
9Reflow profile recommendation
9SMT experiment examples
X Q& A
19
OMAP4xxx SMT Evaluation
Preliminary experiments performed concurrent to
package design and material selection
Experiments
Dippable mat'l
Dipping plate depth
Reflow Atmosphere
Reflow preheat time (sec)
Dwell time for TMV package
placement (ms)
Dwell time for memory
package dipping (ms)
Dwell time for memory
package placement (ms)
Sample Size
Rejects
Yield
1
2
3
4
5
6
7
Senju
Deltalux901K3
Flux
160um
N2
70-80
Flux
170um
Air
80-90
Flux
170um
N2
80-90
Flux
170um
N2
60-65
Flux
170um
Air
60-65
Paste
140um
N2
70-80
Senju
Deltalux901K3
Flux
170um
N2
70-80
300
300
300
300
300
300
300
300
300
300
300
600
600
300
300
300
300
300
500
500
500
1635
114
93%
204
0
100%
2310
5
100%
1700
37
98%
972
0
100%
216
3
99%
700
8
99%
Senju Senju Senju Senju Senju M705529D-1 529D-1 529D-1 529D-1 TVA03.9-F
Total Air Atmosphere
Sample Size
3335
Rejects
151
Yield
95.5%
Total N2 Atmosphere
Sample Size
4402
Rejects
16
Yield
99.6%
Summary:
• Nitrogen atmosphere better than air
• Senju 529D-1 better in air than Senju 901K3*
• Dipping depth too deep*
*reference follow up tests in this report
20
OMAP4xxx DOE Experiments
21
OMAP4xxx DC (TMV) SMT Evaluation
DOE1
22
DOE1 Set Up
OMAP4 Package
Memory Package
SMT Board
Bottom BGA Paste
Top BGA Flux or Paste
Solder Stencil
Thickness (um)
Shape
Outer Four Rows
Diameter (um)
Inner Rows
Diameter (um)
Memory Package
Dipping Depth (um)
Reflow Profile
Pre-heat time
Time above Liquid
Peak temp and time
Reflow Atmosphere
Sample Size
Yield
Opens (DC net test)
Shorts (X-Ray)
Flux Dipping
Paste Dipping
OMAP4 CBS Daisy Chain
OMAP4 CBS Daisy Chain
Mock Up
Mock Up
NSMD Pads
SMD Pads
Shenmao PF-606-P (SAC305)
Senju Deltalux-901K3
(No-Clean dipping flux)
Laser and electro-polished
Shenmao PF-606-P (SAC305)
Senju M705-TVA03.9F
(SAC305, No-Clean dipping paste)
Laser and electro-polished
80
Round
80
Round
250
250
200
200
120 - 140um
See other table
70-80 sec
70-80 sec
65 - 75 sec
65 - 75 sec
245-250oC
245-250oC
Nitrogen (700 O2 ppm)
Nitrogen (700 O2 ppm)
540 packages
270
0/540
See other table
0/540
See other table
23
DOE1 Results
Run 1
Flux Dipping
Run 2
Paste Dipping
190um
190um
Senju Deltalux-901K3
(No-Clean dipping flux)
> 8 hours
Senju M705-TVA03.9F
(SAC305, No-Clean dipping paste)
120 - 140um
See below table
540 ea
270ea
0/540
See below table
0/540
See below table
Memory Ball Height
Top BGA Flux or Paste
Warm up time
Memory Package
Dipping Depth (um)
Sample Size
Yield
Opens (DC net test)
Shorts (X-Ray)
Run
2-1
Bottom BGA Paste
Warm up time
Top BGA Paste
Warm up time
Memory Package Dipping
Depth (um)
Yield
Opens (DC net test)
Shorts (X-Ray)
30 min
2-2
See below table
2-3
2-4
2-5
Shenmao PF-606-P (SAC305)
> 18 hours
Senju M705-TVA03.9F (SAC305, No-Clean dipping paste)
> 18 hours
140
125
124
122
122
0/54
54/54
0/54
2/54
0/54
0/54
0/54
0/54
0/54
0/54
24
Top BGA Typical Solder Joint Defects
Defect: Random single or double non-wet solder joints
Root Causes:
• Insufficient flux
• OMAP and/or Memory solder ball height and gap variation during
the reflow process
Solution: Flux volume transfer control
25
POP SMT Process Variables
Paste &
Flux
Solder Paste
and Flux
Application
Solder
Stencil
Solder Alloy
Solder
% Metal
Particle Size
Paste
Thixotropy/
Slump
Viscosity
Package
l
el
Dw me
Ti
y
h
pt rac
De c u
Ac U p
m
ar
W
Opening
Memory Dip
Print
Speed
Size
Flux/Paste
Material
Squeegee Volume Transfer
Opening
pressure
shape
Thickness
Snap off
Surface
Separation
Flux
Mfg
Shelf/
finish
Speed
Activation Working Life
Method
SMT
Success
Memory Pkg
BGA Pitch Solder
Atmosphere:
Bd & Panel
Alloy
Pkg Size
Air or N2
Design
• TI Controlled
Accuracy
Warpage
• Standard POP
Temperature
TMV Size Solder
Pressure
Ball Size
Variables
Profile &
BOM
Warpage
• POP-TMV
Uniformity
Thermal
Dwell Time
Mold Cap
Variables
Pad Design
Load
Thickness
Pick &
Reflow
Customer
Board
Place
Process
26
OMAP4xxx DC (TMV) SMT Evaluation
DOE2
27
DOE2 Set up: Screen Print Stencil Design & Reflow Process
Stencil Designs
Shape
1
2
Round 80 Round
Variable,
80
Nano
Variable
3
4
Round
80
Square
80
Uniform
5
6
7
8
Square Square 80
Round 100 Round 100
80
variable
Uniform
Uniform
Variable
Nano
Thickness (um)
80
80
80
80
80
80
100
100
Zone C
Zones A & B
Opening Ratio
Zones C
Zone A & B
250
200
250
200
250
250
250
250
250
200
250
200
210
210
255
255
0.78
0.63
0.78
0.63
0.78
0.78
0.78
0.78
0.78
0.63
0.78
0.63
0.53
0.53
0.64
0.64
Option 1
Option 2
Option 3
R/T-120C
70
R/T-120C
90
R/T-120C
110
120-180c
90
120-180c
110
120-180c
130
235
60
o
3 /sec
240-245
80
o
3 /sec
245-250
100
o
3 /sec
Reflow Profiles
Preheat Zone
Temperature
Time
Soak Zone
Temperature
Time
Reflow Zone
Peak Temperature
Time above Liquid
Cooling Zone
28
DOE2: Solder Paste
and Flux
Flux for memory dipping:
Senju DELTALUX 901K3
Solder paste for POP mount:
Tamura TLF-204-19A
Solder paste for memory dipping:
Senju M705-TVA03.9-F
29
DOE2 Results
Stencils
Legs
1 4 5 7 8
POP Memory Process
Dipping
Material
Paste:
Senju M705TVA03.9F
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Flux:
Senju 901K3
(15 air bake,
150oC, 8 hrs)
Dipping
Depth
(um)
105
140
180
140
130
130
130
130
130
130
130
130
130
130
Reflow
Profile
Reflow
Atmosphere
N2
A B C Air
Qt'y
<700ppm
O2
Opens
Shorts
Bott
Top
om
Any
Bottom
Top
100%
100%
100%
100%
100%
99.5%
100%
100%
100%
100%
100%
100%
100%
100%
100%
100%
0%
65%
100%
99.5%
99.5%
100%
0%
0%
99%
0%
6%
100%
0
0
Yield
216
216
54
216
216
216
216
216
216
108
108
216
108
108
0
0
0
0
0
1
0
0
0
0
0
0
0
0
76
0
1
1
0
216
108
1
216
102
0
0
0
54
0
0
0
0
0
0
0
0
0
0
0
130
108
0
108
0
100%
0%
130
108
0
0
0
100%
100%
108
N/A
N/A
N/A
N/A
N/A
108
N/A
N/A
N/A
N/A
N/A
108
108
2862
0
0
0
0
0
0
100%
100%
100%
100%
16
(15 air bake,
150oC, 8 hrs)
17-1
N/A (PreStack)
17-2
N/A (PreStack)
17-1a
17-2b
Paste:
Senju M705140
TVA03.9F
Flux:
130
Senju 901K3
17-1 pre-stack
17-2 pre-stack
Total
30
Memory Dipping Defect Example
Black ring is flux wetting bottom of memory
package: pulled flux off solder ball
130um ( actual depth)
140um ( actual depth)
Flux Legs
Flux Dipping Mat'l
1
2
Senju Deltalux-901K3
Senju Deltalux-901K3
Dipping
Depth
140um
130um
Flux viscosity with continuous stirring
Reflow Peak
Temp (oC)
240-245
240-245
Reflow
Atmosphere
N2 (<700ppm O2)
N2 (<700ppm O2)
Package
Quantity
216
216
Yield
65%
100%
Flux transfer to memory package is critical:
• Type of flux
• Viscosity of flux
• Dipping depth
• Dwell time of package in flux tray
31
Paste Dipping Experiment Result
105um ( actual depth)
140um ( actual depth)
Reflow Peak
Dipping
Depth (um)
Temp (oC)
Paste
Legs
Paste Dipping Mat'l
1
Senju M705-TVA03.9F
105
2
Senju M705-TVA03.9F
140
3
Senju M705-TVA03.9F
180
240-245
240-245
240-245
180um ( actual depth)
Reflow
Atomosphere
N2 (<700ppm O2)
N2 (<700ppm O2)
N2 (<700ppm O2)
Package
Yield
Q'ty
216
100%
216
100%
54
0%
32
DOE2 Result
Summary:
• Bottom BGA yield robust vs. stencil design
• Top BGA yield sensitive to flux dipping process
• Depth
• Viscosity
• Dwell time
• Top BGA dipping in paste successful: verification
required
• Nitrogen atmosphere (<700ppm O2) required in this test
• Experiments will continue to define assembly capability in
an Air reflow atmosphere
33
OMAP4xxx DC (TMV) SMT Evaluation
DOE3
34
DOE3 Set up:
Reflow Profile
Preheat Zone
Temperature
Time
R/T-120C
90
Soak Zone
Temperature
Time
120-180c
110
Stencil Design
Shape
Surface Finish
Thickness (um)
Opening Diameter(um)
Zone C
Zones A & B
250
200
100% Volume Transfer Rate
3
3926991
Zones C (um )
Reflow Zone
Peak Temperature
Time above Liquid
Cooling Zone
240-245
80
o
3 /sec
Material in DOE3
Round 80 Variable
Laser Job nano coating
80
3
Zone A & B (um )
2513274
Opening Ratio
0.78
0.63
Zones C
Zone A & B
Recommended
reflow
atmosphere
Paste
Senju M705-TVA03.9K
Air
Paste
Senju TVA 107K
Air
Flux
Senju Deltalux 529D-1
Air
Flux
Senju Deltalux-GTN68-HF
Air
Notes
[Halogen Free ROLO (<500ppm) per JSTD004A, No-Clean Dip Paste]
[Halogenated ROL1 per JSTD004A, No-Clean
Dip Paste]
[Halogenated ROL1, No-Clean Dip Flux]
[Halogen Free ROLO (<500ppm) per JSTD004A/B, No-Clean Dip Flux]
35
DOE3: Results
Dipping Dipping
With
Dwell
Depth
EMI
Memory Dipping Mat'l
Time
(Actual
Shield
(ms)
depth)
Senju TVA
130
600
No
1
Tamura TLF-204-19A
Paste
107K
Senju TVA
130
900
No
2
Tamura TLF-204-19A
Paste
107K
Senju M705130
600
No
3
Tamura TLF-204-19A
Paste
TVA03.9K
Senju M705130
900
No
4
Tamura TLF-204-19A
Paste
TVA03.9K
Senju M705130
600
No
5
Tamura TLF-204-19A
Paste
TVA03.9K
Senju M705130
900
No
6
Tamura TLF-204-19A
Paste
TVA03.9K
Senju
7
Tamura TLF-204-19A
Flux
Deltalux
130
600
No
529D-1
Senju
8
Tamura TLF-204-19A
Flux
Deltalux
130
900
No
529D-1
Senju
9
Tamura TLF-204-19A
Flux
Deltalux130
600
No
GTN68HF
Senju
10
Tamura TLF-204-19A
Flux
Deltalux130
900
No
GTN68HF
Senju
11
Tamura TLF-204-19A
Flux
Deltalux130
900
Yes
GTN68HF
Senju
Tamura TLF-204-19A
Flux
Deltalux130
900
No
12*
GTN68HF
Senju TVA
Tamura TLF-204-19A
Paste
130
900
No
13*
107K
*Preconditioned: 150C for 1.5 hrs in Air, followed with 8 hrs at 85RH/85C
DOE
Leg
Bottom BGA Printing
Material
Reflow
N2
Air (O2<700
ppm)
Totals
Q'ty
#
#
Yield %
Opens Shorts
Panels
PKGs
4
216
1
0
99.5
19
1000
0
0
100
1
54
24
0
56
1
54
19
0
65
1
54
0
0
100
1
54
0
0
100
1
54
13
0
76
1
54
22
0
59
4
216
1
0
99.5
19
1000
0
0
100
3
18
0
0
100
2
108
108
0
0
2
108
108
0
0
59
2990
36
DOE3 Result
Summary:
• Flux and Paste chemistry and rheology are critical factors
for use in an air reflow atmosphere
• Time out of refrigeration and time worked in dipping tray
affects coating uniformity
• Dipping time change from 600ms to 900ms improved yield
• A paste that did not work in air worked in nitrogen reflow
atmosphere
• Bottom BGA process continues to be robust
• Pre-conditioned parts shifted and yielded zero bottom BGA
connections: X-ray of top BGA looked normal but unable
to test due to lack of connection through bottom BGA
37
Brush with flux for repair in TMV level (1)
1
2
4
3
5
-Use cotton swab to apply adequate flux at the side-walls of defective POP.
-Reflow then Check in X-ray (see next slide) & O/S test.
Size
5
Evaluate samples
Test result (Xray, O/S)
Flux type
Repair level
OK
NG
Senju 529D-1
TMV
5
0
38
Brush with flux for repair in TMV level (2)
1
1 2
1
2
2
3
1 2
3
Non-wet Solder Joint
The non-wetting TMV joints show as
3 balls overlapped with bottom BGA
ball in X-ray inspection.
Repaired Solder Joint
The defect TMV joints are re-healed
& show as 2 balls overlapped with
bottom BGA ball in X-ray inspection.
39
Backup
40
Solder ball analysis by X-ray -1
1-pass reflow
Picture: POP and Memory mount on PCB. Before reflow.
Solder paste printing check was good. Memory is mount on POP by flux
with good accuracy.
41
Solder ball analysis by X-ray -2
1-pass reflow
Bottom
NSMD
Top
Picture: Memory mounted by flux, NSMD board, After reflow
Memory solder ball was jointed with POP showing good barrel shape
42
Solder ball analysis by X-ray -3
1-pass reflow
Picture: Memory mounted by flux, SMD board, After reflow
Memory jointed with POP with good barrel shape.
No anomaly is found for POP solder balls.
43
Solder ball analysis by X-ray -4
1-pass reflow
Picture: Memory mounted by solder paste, SMD board, After reflow
Excess solder paste caused solder ball short
44
Solder ball analysis by X-ray -5
1-pass reflow
Picture: Memory mounted by solder paste, SMD board, After reflow.
Reduced solder paste dipping depth then solder ball short did not happen
45
Solder ball analysis by X-ray -6
1-pass reflow
2nd reflow result. Run POP+Memory mount board reflow again
Paste dip, After reflow, SMD pad
Package upward
Paste dip, After reflow, SMD pad
Package downward
2nd Reflow
2nd Reflow
Memory solder ball joint did not change by 2nd reflow
46
Solder Paste
Screen Printing
Printed Paste
Solder Stencil
47
Solder Reflow
Reflow Profile
Reflow Setup
Reflow Oven
48
Calculating Solder Paste Volume to
Prevent Shorts in the Center Array
Pre-Reflow
Max. Reflow Temperature
Post-Reflow Room Temperature
Factors affecting location of neutral point:
• Number and location of solder balls
Neutral solder ball at
• Solder surface tension
maximum reflow temperature • Pad shape
(nominal height)
• Weight of OMAP and Memory packages
• Phone board warpage
• Temperature ramp, uniformity & maximum
• Paste
• Reflow atmosphere
Sketches not to scale
49