Introduction of IMS Technology for Advanced Solder
Bumping on Wafers / Laminates
Senju Metal Industry Co.,TW Deputy General Manager
Lewis Huang
Science & Technology IBM Research – Tokyo
Yasumitsu Orii, PhD
What is IMS (Injection Molded Solder) technology ?
Mask (resist)
Injection of molten pure solder into through holes in N2 environment
→ molten solder wets on metal pads (or metal pillars) w/o flux.
→ formation of IMCs (intermetallic compounds) at solder/pad interface.
→ solidify solders in N2 environment.
Very simple process
Green process
• No flux, No formic acid
• Minimum solder waste
Pure solder injection
• Higher solder volume
• Extendible to very fine pitch
• Solder alloy flexibility
One pass for multiple solder sizes Wafer or laminate
Metal pad
IMS head
Molten Solder
Transfer
Solder
Mold fill
• C4NP (C4 New Process) for wafer bumping
- in volume production in IBM since 2007
Glass mold
Mold fill + Transfer -> ”One Process”
Wafer
Reusable Mask IMS for laminate bumping
- ideal for high volume solder
- available to skip solder bumping on chip side.
Mask-less IMS for laminate bumping
- ideal for low cost & fine pitch
application
IMS with Resist Mask for wafer/laminate bumping
- Direct solder deposition on
wafers/laminates without transfer
Solder
IMS (Injection Molded Solder) technologies
Kapton mask Remove mask
Laminate
Solder
As received laminate
Cu pillar Resist mask
Strip resist mask
Laminate
Resist mask Solder
Cu or Ni UBM
Wafer
Resist mask IMS & strip resist mask
& Etching seed layers
C4 bump
Solder Capped Cu pillar bump
IMS (Injection Molded Solder) technologies
No voids in solders
Easy control of alloy composition
Can make very high volume
solder on laminates & wafers
Good for island type I/O pads
such as laminates
No voids in solders
Easy control of alloy composition
No limitation in a size
No limitation in pitch
Very low cost
→ No mask & no alignment
→ No cost increase in finer pitch
No voids in solders
Easy control of alloy composition
Can make very high volume
solder on laminates & wafers
Can be applied to finer pitch
below 100 um pitch
Can be applied to panel size
laminates and wafers
Tooling investment is required
Difficulty of high volume
production
Currently, only singulated
laminate or wafer is possible.
Tooling investment is required
Lower solder volume
Tooling investment is required
Photolithography is required
Need some evaluation or
development for the resist
materials and process on high
volume production
Mask-less IMS Reusable mask IMS IMS with resist mask
Tec
hn
olo
gy
Pro
s.
Co
ns.
laminate laminate Wafer or laminate
Target area (Possibility of IMS technology)
IMS has a wide capability of the solder bumping compared with the commercially available bumping technologies;
- from wider pitch (big bump) to finer pitch (small bump) applications
- flexibility of solder alloy from pure Sn to ternary with minor alloy doping
Wafer IMS technology
solder bumping on wafers
20μm Cu
1μm Cu
2μm Ni
SAC 305
60
μm
2
0
Wafer IMS results on different Cu thickness
• 40μm thick Cu pillar • 2μm thick Cu UBM
As received
After IMS
After stripping dry film
Dry film (60μm) Cu pillar
• Particular geometry achieved is unique in industry.
Straight sidewalls w/ round top of the solder bump on pillar
→ No need additional reflow. It should help with fine pitch.
• Molten solder injection w/o flux → No voids in solders.
• Ability to control solder composition readily.
• No change in throughput even though solder volume increased.
Cu UBM Dry film
SAC 305 Dry film SAC 305 Dry film
Wafer IMS bumping results on 8 inch wafer
50μm
50μm diameter
50μm
75μm diameter
Wafer IMS demonstration with various opening size in 8 inch wafer !!!
solder bump solder bump
Demonstrated Wafer IMS bumping with 8 inch wafer
Opening size : 50μm ~ 200μm
Shape : Circle & Square
100μm,
250μm
pitch
75μm,
125μm
pitch
200μm,
400μm
pitch
50μm,
200μm
pitch
75μm,
175μm
pitch
150μm,
300μm
pitch
75μm,
225μm
pitch
75μm,
150μm
pitch
175μm,
350μm
pitch
Wafer bumping technologies
Micro-ball mounting Electroplating Wafer IMS
HVM tooling is in market
→ bumping down to 60um dia.
balls.
Enough knowledge for processes,
qualification, and cost.
Ability to control solder
composition readily.
No voids in solders.
HVM tooling is in market.
Enough knowledge for processes,
qualification, and cost.
Easy to achieve fine pitch.
Ability to control solder composition readily.
→ Not limited to binary composition. Bump height uniformity, even for different I/Os size and shape and Cu pillars have non-uniformity.
No need of flux. No voids in solders. Green process / Minimum waste Head change : solder alloys change.
If company does not have solder plating tools, easy to start IMS with low cost.
Question of manufacturing tool
availability for bumping 25um dia.
balls. → Tooling development could
be required for fine pitch.
Cost increase for making and
handling small size balls.
No way to use different I/Os size.
Only pure Sn or binary solder
composition. Solder composition uniformity. Possible voids in plated solders. Additional reflow after solder plating.
Cost difference in Cu plating vs. solder plating.
Cost for plating solutions and handling chemical waste of plating solutions.
Process & material optimization required.
(prototype tool : ready, material : under
development)
HVM tooling optimization.
Ad
van
tag
es
Co
nce
rns
Tec
hn
olo
gy
Laminate IMS Technology
solder bumping on organic laminates
~ 63
μm
Solder mask
Cu pad
Organic Laminate
Laminate IMS technologies
Organic laminate
(a) Alignment mask
(c) Solidification of solder
Reusable film mask
(b) Molten solder injection
N2
(d) Mask separation
(d) Reflow w/ flux
wide
(c) Solidify solder
(a) As received laminate
Organic laminate
Solder
resist (SR)
• Mask-less • Reusable Mask
(b) Apply resist mask
(c) Opening resist mask (lithography)
(a) Opened SR
Organic laminate
(f) Reflow (optional)
(e) Strip resist mask
(d) IMS in nitrogen
Solder
• IMS with resist mask
(b) IMS
N2
Laminate IMS technologies
• A: Mask IMS (132μm pitch)
Average Std
17.9 mm 1.8
• B: Mask-less IMS (132μm pitch)
No residue on solder resist
~ ideal for low cost (very fine pitch) ~
Solder height above solder
Solder volume and bump height are depended on solder resist opening design.
I
H
G
F
E
D
C
B
A
IMS bump height distribution tighter then with paste printing
Mask IMS bump height over solder resist
*Mask IMS
53.3μm over SR.
Summary
IMS technology was demonstrated
→ with organic substrates and wafers
→ on different Cu thickness
(Capable for solder capped Cu pillar structure)
→ with 8 inch size wafers
→ with 13μm diameter and 50μm height bumps
→ with TSV (Through Silicon Via)
“IMS” is an attractive technology, and IMS has many
possibilities as well as solder bumping ! Bumping on Si / Organic / Glass IP
BGA ball bumping
TSV filling
Pre-soldering on C4 pads
Laminate via filling
© 2013 Senju Metal Industry Co., Ltd. All rights reserved.
Senju Metal Industry Co.,ltd
Introduction of IMS technology for advanced
solder bumping on wafers / laminates
Equipment Portion
Key Features
－Fine Pitch
－Flux less
－Solder Alloy Flexibility
－Variable bumps
－Green Process
Contents
－IMS Tools, Structure &
Process
－Micro Bump Status
－Cross Section, IMC &
Bump Height
IMS Tools（Laboratory tool)
Developed year: 2011 2013
IMS-50 IMS-200
2014 (Evaluating now)
IMS-300
IMS-50: □50mm
IMS-200: 8 inch wafer
IMS-300: 12 inch wafer
<Work size>
IMS Head
Heating plate
Heating plate
Cooling plate
Index table
1st Stage
2nd Stage
Loader / Unloader
Pre-heater
3rd Stage IMS 4th Stage
Cooling
Carrier
Tool structure
Touch panel operation
Condition~
Solder ： SAC305
3rd stage ： 250℃
Solder temp ： 250℃
Head pressure ： 0.3MPa
Solder pressure ： 0.06MPa
Head speed ： 2mm/s
Resist thickness: 20um
17
wafers / Laminates
Melting solder
N2 pressure
IMS process
・Mask
・SR
・DFR
Micro bump status (Under Φ50um)
Pad
Diameter Φ50um Φ40um Φ30um Φ20um
Pitch 100um 80um 60um 40um
×500
×1500
Condition~
Solder ： SAC305
3rd stage ： 250℃
Solder temp ： 250℃
Head pressure ： 0.3MPa
Solder pressure ： 0.06MPa
Head speed ： 2mm/s
Resist thickness: 20um 8 inch wafer
19
Pad
Diameter Φ50um Φ40um Φ30um Φ20um
Pitch 100um 80um 60um 40um
Cross
section
IMC
19
×3000 ×2000 ×1700 ×1500
Measured value (N=20) Unit: um Ave. SD
Φ50 10.7 11.2 11.3 11.5 12.3 12.0 11.5 10.9 11.9 11.6 11.2 11.0 11.1 10.9 11.8 12.0 12.0 12.0 11.5 11.2 11.48 0.459
Φ40 10.7 11.4 10.1 10.2 11.5 11.6 11.4 11.1 11.7 12.0 10.5 10.7 10.4 11.4 11.8 11.5 10.7 10.3 10.3 10.5 10.98 0.609
Φ30 8.2 8.0 8.3 7.9 9.8 8.1 8.0 9.4 9.0 8.1 9.2 8.6 9.5 8.5 9.3 8.0 9.5 9.1 9.3 9.0 8.73 0.631
Φ20 5.4 5.3 4.5 4.3 4.6 5.2 4.8 5.3 5.2 5.3 5.3 4.4 4.8 4.3 4.7 4.9 4.5 4.5 4.4 5.6 4.86 0.411
Bu
mp
he
igh
t
Resist
opening
size
Wafer
Re
sis
t: 2
0u
m
Solder: SAC305
Solder temp: 250℃
Plate temp: 250℃
Solder pressure: 0.06MPa
Head speed: 2mm/sec
Resist thickness: 20um
Laboratory location：Senju Metal Industry Co.,Ltd HQ
23 Senju Hashido-Cho Adachi-ku Tokyo, Japan 120-8555
<Contact person>
Takashi Nauchi
Email: [email protected]
～Technical support～
Laboratory & Evaluation
IMS Demonstration
Sample Preparation
Evaluation & Inspection
Clean room: Class 1000 (0.5um)
IMS-50 IMS-200
If you are interested in IMS
technology, please contact us!
<Representative person>
Lewis Huang / 黃 智 堯
Email: [email protected]
Key Features
－Fine Pitch
－Flux less
－Solder Alloy Flexibility
－Variable bumps
－Green Process
SMIC HQ in Tokyo
SMIC Factory in Tochigi SMIC Product Lineup
Thanks for your attention!!!
