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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Innovative Approach to
MEMS Contactor
Norihiro OhtaNidec-Read Corporation – Kyoto, Japan
BiTS Workshop
March 4 - 7, 2018Conference Ready
mm/dd/2014
Pete RoganNidec SV TCL – Tempe, AZ
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Overview
• Background
• MEMS Spring Probe Definition
• Manufacturing Process Detail
• Design Process Detail
• Advanced Features
• Performance Data
• Technology Road Map
• Conclusions
Innovative Approach to MEMS Contactor 2
Human Hair
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Background
• Advanced packaging technologies driving requirements for
innovation in the contactor space
• Fan-out WLCSP (FOWLP) and copper pillar interconnects are
pushing requirements for low-cost, flexible probe technologies
• The confluence of applications and packaging requires more than
a “one size fits all” approach
• A MEMS spring pin developed for IC substrate contact test
fixtures is finding new applications in WLCSP, socket, and flip
chip probe applications
Innovative Approach to MEMS Contactor 3
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
MEMS Spring Pin Probe Definition• Simple structure with spring and snap-fixed two plungers
• Low resistance and high CCC
Innovative Approach to MEMS Contactor4
PCB Side Plunger
MEMS Spring
Various Tip Shape
(Crown, Needle, Flat・・・)
Snap-fit Fix
DUT Side Plunger
Stable contact against MLC/MLO
Photo-Lithography Method
Inner Au-Plating
Electroforming Ni-Pipe
Low Resistance
High Accuracy Inner/Outer Dia.
Flexible Spring design
by Exposure data
H3C Plunger + Au-Plating
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Manufacturing Process – Electroformed Pipe
Innovative Approach to MEMS Contactor 5
Step 1 - Stainless wire acts as mandrel for electroforming process
Step 2 – Au Plating
Step 3 – Ni Alloy plating
• Automated continuous process
Inner diameter accuracy ±1µm
Inner Au Plating
Outer diameter accuracy ±1µm
High accuracy Ni pipe
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Manufacturing Process – Photolithography
Innovative Approach to MEMS Contactor 6
Θ Motion
Z-Motion
Laser Unit
Ni Pipe
Resist
Coat
Laser Expose
Develop
Etch Resist Remove Core wire
Remove
Clean
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Manufacturing Process – Photolithography
Innovative Approach to MEMS Contactor 7
After Resist Coat/
Laser Expose/Develop After Etch After Resist Removal
After Core Wire Removal
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Design Process – Fundamental Equations
Innovative Approach to MEMS Contactor 8
δ=8𝑁𝑎𝐷3𝑃
𝐺𝑑4
Na= number of turns
G = Modulus of
transverse elasticity
d
D
P
δ δ
D
τ=8𝐷𝑃
𝜋𝑑3
δ =0.9𝜋𝑁𝑎𝐷3𝑃(𝑏2+ℎ2)
𝐺𝑏3ℎ3
τ =0.8𝐷𝑃 (2×𝑏+ℎ)
𝑏2×ℎ2
P
h
b
Adapt fundamental
coil spring equations
to account for thin
rectangular cross
section of MEMS
spring
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Design Process Effect of Design Parameters on Spring Force and Stroke
Innovative Approach to MEMS Contactor 9
h
(1)
(2)
(3)
h Na×2
h×2
Sp
rin
g F
orc
e⇒
Stroke⇒
(2)(1)
(3)
δ(Stroke) =0.9𝜋𝑵𝒂𝐷3𝑃(𝑏2+𝒉2)
𝐺𝑏3𝒉3
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Innovative Approach to MEMS Contactor 10
h
(1)
(2)
h
D×2
D
Stroke⇒
δ(Stroke) =0.9𝜋𝑁𝑎𝐷3𝑃(𝑏2+ℎ2)
𝐺𝑏3ℎ3S
prin
g F
orc
e⇒
(2)(1)
Design Process Effect of Design Parameters on Spring Force and Stroke
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Advanced Features
• Current Path ・・・ Low resistance and high CCC
Innovative Approach to MEMS Contactor 11
Current Path
Stroke
Primary current path is through the low-resistance plunger and center barrel section
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Advanced Features – Spring Rotation
Design With RotationTorque action helps break
through oxide layers
Innovative Approach to MEMS Contactor 12
Rotation
Angle
X°
0°
Rotation
Angle
0°
X°
2
Design Without RotationAxial force with no torque
minimizes bump/pad damage
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Innovative Approach to MEMS Contactor
Advanced Features – Plunger Tip Shape
• Select tip shape appropriate for the application
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Crown
Rotation
No-Rotation
Flat
Needle
Round
Solder
Bump
Al Pad
Au Pad
Cu Pillar
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Performance Data – Current Carrying Capability
Innovative Approach to MEMS Contactor 14
Test Method per ISMI Probe Council Current Carrying Capability Measurement Guideline
CCC performance is maximized at full design stroke
Maximum plunger/
barrel overlap
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Performance Data – Custom Spring Force by Design
Innovative Approach to MEMS Contactor 15
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Performance Data – Durability Test
Innovative Approach to MEMS Contactor 16
Over Travel (µm)
–
Consistent Force over Life
.Number of Cycles
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Performance Data – Durability Test Diagram
17Innovative Approach to MEMS Contactor
Au Wafer
1M Cycles 200 Cycles
↓
Cleaning
Room Temp (25°C)
Cres on Bump
Room Temp
Mechanical Cycling
700
Cycles
↓
Cleaning
↓
300
Cycles
↓
Cleaning
PCB
Probe Head
100 Probes
Bump Wafer Bump Wafer Bump Wafer
Low Temp (-40°C)
Cres on Bump
High Temp (125°C)
Cres on Bump
Cres Stress Test
200 Cycles
↓
Cleaning
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Page 18
Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Performance Data – Durability Test25°C Bump Contact Performance
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OD vs Cres @ Room Temp 200TD @ OD300µm
・N = 100 probes
・Stable Cres < 2Ω
Φ0.095mm
8.7mm
Innovative Approach to MEMS Contactor
After 1M Cycles After 1M Cycles
Cycles
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
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OD vs Cres at Cold Temp 200TD (OD300µm)
• Low temperature performance generally consistent with room temp.
• Cres improvement after cleaning more pronounced
Innovative Approach to MEMS Contactor
Performance Data – Durability Test- 40°C Bump Contact Performance
After 1M Cycles After 1M Cycles LT
Cycles
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
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OD vs Cres at Cold Temp 700+300TD (OD300µm)
• High temperature performance remains <2Ω up to 200 cycles
• Cres Stress Test shows significant degradation 200-700 cycles
• Cres performance stabilizes after cleaning
Innovative Approach to MEMS Contactor
Performance Data – Durability Test125°C Bump Contact Performance
After 1M Cycles After 1M
Cycles
After700TD
Tip cleaning
After 1kTD
Tip cleaning Skip 200TD
Tip cleaning
Cycles
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
21Innovative Approach to MEMS Contactor
Performance Data – Frequency
• S-G 160um
• SPICE simulation application
• Probe only simulation
Φ0.095mm
8.7mm
Φ0.072mm
4.9GHz
Frequency
• S21 (-3db, rectangular wave)
• 1.6GHz (=4.9GHz/3)
Test Result
Test Condition
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Performance Data – Probe Mark Bump Damage
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• Probe mark is smaller @ low temp but Cres remains stable
• Probe mark becomes larger @ high temp
Innovative Approach to MEMS Contactor
125°C
- 40°C
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Performance Data Heat Resistant Ni Alloy Spring Material
Innovative Approach to MEMS Contactor 23
Full Stroke
160℃20hr
180℃20hr
140℃20hr
200℃20hr
-40℃20hr
30%
10%
20%
Sh
rin
kag
eR
ati
o
50%
40%
30%
10%
20%
50%
40%
Standard Alloy
High Temp Alloy
Low Temp High Temp Shrinkage
R.T.R.T.
Shrinkage Ratio =Full Stroke
Shrinkage
Temp(℃)
Initial
Length
After
Length
Hot Plate
Exposure
*High Temp Alloy used for all data in this presentation
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
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Technology Road Map
350 300 250 200 150 130 100 80 65 55・・・・・
Manufacturing
Coming Soon
Development(Ongoing)
Pathfinding
Pitch (µm)
Φ95µm Φ70µm Φ50Φ120µm
Φ41µmΦ125µm
350-250µm Pitch
WLCSP/IC Socket
180-100µm Pitch
Flip ChipSoC/AP 80µm - 110µm Pitch, copper pillar, micro-bump
Tight Pitch, Small Pad 50µm - 80µm Pitch
Innovative Approach to MEMS Contactor 24
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Technology Road Map
Highly Scalable MEMS Technology
Innovative Approach to MEMS Contactor 25
Φ95/80µm
Pitch200μm
Pitch150μm
Φ50/40µm
Pitch 65μm
Φ125/100µm
Φ41/32µm
Pitch 55μm
With the same basic probe structure, it is easy to adapt design
from wide pitch to narrow pitch
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Touch Down! - Contact TechnologyBiTS 2018Session 2A Presentation 4
March 4-7, 2018Burn-in & Test Strategies Workshop www.bitsworkshop.org
Conclusions
• The MEMS SPRING PROBE technology can easily provide small
diameter probes that can not be realized with conventional coil springs
• Simple structure realizes high CCC and low CRES which is stable over
life and temperature
• Minimize Bump damage by Rotation control and free tip shape
• Alloy material Spring can be used under high temperature
• Roadmap to 55 µm pitch
• Wide variety of pin specs achievable using common manufacturing
process and no hard tooling
Innovative Approach to MEMS Contactor 26
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