inemi Nano-Attach inemi Member Report

Transcription

1 inemi Nano-Attach inemi Member Report Nano-Attach Team 4 September 2008

2 Thrust Area: Miniaturization TIG: Board Assembly Nano-Attach Project Novem ber 08 Develop low or room temperature assembly processes that have the potential to improve field reliability, streamline manufacturing and reduce costs Strategy Issues Graphics Research and develop nanotechnology based dry adhesive technologies (e.g., nano-velcro or biomimetic ( gecko foot ) systems) that can be used to replace solder attach systems Develop techniques to integrate nanostructures with electronic components & identify cost effective implementation schemes Project Lead: Hope Chik (Formerly Motorola) Project Co-Lead: None Limited global suppliers of nanomaterials Novel technology with need to develop new evaluation methods / techniques Phase 1 completed. Need to decide whether to continue with Phase 2. Tactics Milestones and/or Deliverables Plan Actual Phase 1: Define requirements necessary to adapt nano-structure attachment schemes in electronic assembly. Identify and evaluate currently available nano-attach technologies and explore these approaches Phase 2: Demonstrate feasibility with proof-ofconcept material evaluation (mechanical, electrical, thermal properties) Phase 3: Demonstrate nano-attach assembly prototype Initiative Launched SOW & PS Completed Define requirements for Electronic Systems Nano-attachment benchmarking for Electronics Sysstems Final Project Team Slide Presentation 4Q-06 1Q-07 2Q-07 3Q-07 2Q-08 Final Membership Slide Presentation 3Q-08 4Q-06 1Q-07 2Q-07 3Q-07 3Q-08 1

3 inemi Nano-Attach Team Members Page 2

4 Executive Summary & Project Outline Nano-Attach Team 26 June 2008

5 Table of Contents 1. Executive Summary & Project Outline 2. Background 3. Applications Targeted 4. Requirements & Technology Gaps 5. Phase 2 Attributes Page 4

6 Nano-Attach Project Goals Phase 1: Discovery and Concept Development Define application requirements Benchmarking nano-attach technology Cost effective implementation Currently at this stage completed Phase 1 pre-phase 2 Go / No Go Phase 2: Evaluation and Proof-of-Concept Material study Design guidelines Assembly development Go / No Go Phase 3: Demonstration and Prototype Build working prototype Develop supply chain Page 5

7 Phase 1: Discovery and Concept Development Deliverables: Publish design targets for industrial development Publish design targets derived from Phase 1 findings Generate interest in the electronics industry Attract new players Accelerate development Refine project plan, deliverables, and timeline for Phase 2 Publish summary for inemi members Recommend go/no-go for Phase 2 Issue: Is the material technology mature enough to have a high probability of success in Phase 2? Gate 1: Go / No Go Page 6

8 Phase 2: Evaluation and Proof-of-Concept Deliverables: Define and develop evaluation vehicle(s) Define materials characterization methods Performance assessment using evaluation vehicle(s) Assembly Reliability Develop material design guidelines Publish summary of test results Refine project plan and timeline for Phase 3 Publish summary for inemi members Recommend go/no-go for Phase 3 Issue: Is the technology mature enough to have a high probability of success in Phase 3? Gate 2: Go / No Go Page 7

9 Phase 3: Demonstration and Prototype Deliverables: Demonstrate prototype device Present prototype vehicle test results Supply chain identified Publish summary for inemi members Recommend next steps Page 8

10 Background & Motivation Nano-Attach Team 26 June 2008

11 Electronic Assembly Process: Example Component Placement Prepared boards Screen Print Mass Reflow Assemblies Solder paste Parts Drawbacks: Use of elevated temperatures (mass reflow, selective soldering, conductive adhesive curing, etc.) Introduces thermal excursions increasing reliability risks to components and boards Exacerbated with even higher temperature Pb-free assembly processes Individualized solutions for temperature-sensitive components Page 10

12 Biomimetic Inspiration E. Arzt, S. Gorb, and R. Spolenak, From Micro to Nano Contacts in Biological Attachment Devices, PNAS, 100, (2003). Evidence in nature of the use of micro- and nano-scale features as the terminal endings of the foot hairs Heavier species tend to exhibit finer adhesion structures Efficient attachment mechanism allows the species to climb walls or hang on ceilings Page 11

13 What is Nano-Attach Technology? Single-sided Attachment Scheme: One set of nanostructure on one surface Implementation: On board or on component Adhesion Mechanism: van der Waals forces component board nanostructures Double-sided Attachment Scheme: Two sets of nanostructures are required One set of nanostructure on each surface Examples: Hook & loop 2 hooks Macro-scale hook & loop Adhesion Mechanisms: van der Waals forces Mechanical adhesion Entanglement Hook and loop The project is focusing on the single-side attachment approach Page 12

14 Van der Waals Forces Intermolecular forces Present between any and every two surfaces Typical forces between 10 and 1,000 nn per contact point Material dependent Why do two objects tend not to stick together? Major Reason Why? Lack of surface contact points Page 13

15 Definitions: Nomenclature Component Intermediate layer(s) [optional] Component Interface Nanostructure Interface Intermediate layer(s) [optional] Substrate interface Substrate Page 14

16 Definitions: Chirality of Carbon Nanotubes Nanotube Structure Details: Chirality Nanotubes are created by rolling up a hexagonal lattice of carbon (graphite). Rolling the lattice at different angles creates a visible twist or spiral in the nanotube's molecular structure, though the overall shape remains cylindrical. This twist is called chirality. Based on the rolling angle, three types of nanotubes are possible: armchair, zigzag, or chiral. A thirty degree roll (green to blue) produces an armchair pattern and a zero degree roll (green to red) makes a zigzag. Any intermediate angle produces a chiral nanotube. The names 'armchair' and 'zigzag' refer to the pattern of carbon bonds around the tube's circumference. The nanotube's chirality, along with its diameter, determine its electrical properties. The armchair structure has metallic characteristics. Both zigzag and chiral structures produce band gaps, making these nanotubes semiconductors. Page 15

17 What is Nanotechnology? Human hair: 50, ,000 nm What is Nano, Nano 101, Forbes/Wolfe 2002 Page 16

18 How does nanotechnology help in adhesion? Why do two surfaces tend not to stick together? Due to surface roughness Without nanotechnology: Surface 1 Surface 2 With nanotechnology: Surface 1 Number of Contact Points: 1,000,000 /cm 2 1,000,000,000 /cm 2 Surface 2 1,000,000,000,000 /cm 2?? Page 17

19 Example of Nano-Attach Assembly Process Prepared boards Solder paste X Screen XPrint Component Placement Mass Reflow X Assemblies Parts Potential benefits with nanotechnology approach: Room temperature process Streamline manufacturing Improve field reliability Simplified rework Reduce cost Page 18

20 Targeted Applications & Requirements Nano-Attach Team 4 September 2008

21 Library of Opportunities: Potential Applications Mechanical / Structural: Replacement of glue, screws, welding of sheets Packaging / housings Opto-electronic packaging Plug / connectors Thermal Connections: Heat sinks, thermal-electric, interconnects Fans Discrete Components: Resistors, capacitors, inductors, switches, OP amps, RF shield Leaded devices, SMTs IC Chips: Memory, microprocessors, power electronics, control modules, BGAs, flip chip Die attach, embedded packaging, 3D packaging Specialty Parts: Skin / tissue attachment Page 20

22 Library of Opportunities: Mechanical Requirements Adhesion Strength Electrical Mechanical Thermal Weld Structural Solder Epoxy Tape Glue Fan Screws Plug / Connectors Modules / Board Heat sink Electronic Component Opto-Electronics Skin / Tissue Chip / BGA Mechanical Requirements increasing Page 21

23 Library of Opportunities: Electrical Requirements Adhesion Strength Electrical Mechanical Thermal Weld Solder Module / Board IC Chip / BGA Epoxy Discrete Component Opto-Electronics Tape Electrical Requirements increasing Page 22

24 Library of Opportunities: Thermal Requirements Adhesion Strength Electrical Mechanical Thermal Weld Solder Epoxy Fan Module / Board Discrete Component Heat sink IC Chip / BGA Opto-Electronics Tape Thermal Requirements increasing Page 23

25 Proposed Applications by Team: Categorized Mechanical / Structural: RF Shield Attach RF Shields RF Shield Flex Circuit Placement Electrical Connector Thermal Connections: Heat Sink Attach Heat Sink Power Components with Attached Heat Sinks Sweat Soldering of Power Amplifier Modules Integrated Heat Spreader Temperature Sensitive: Opto-Module Attach Flex Circuit to PCB Connection Surface Mount Flex Tab Attach Flex Circuit Connector Temperature Sensitive Components Lamination Process Photo-Sensor Flip Chip Attach Page 24

26 Proposed Applications: Categorized (con t.) Discrete Components: High Voltage Transformer Power Components (high current density) with Attached Heat Sinks Daughter Board Attachment Surface Mount Components Cap Attachment 3D Component Attachment IC Chips: Thin Area Array Devices QFN, DFN, LGA CSP, BGA, CGA BGA Attachment Repair of Balled Devices Gull-Winged Leaded Devices Flip Chip Attachment Photo-Sensor Flip Chip Attach Die Attachment High Frequency Die Attach Page 25

27 Targeted Applications Mechanical / Structural: RF Shield Attach Thermal Connections: Heat Sink Low powered Power Module Heat Sinks Focused on those that currently require additional mechanical attachment Temperature Sensitive: Components Examples: Photo-Sensor Flip Chip Attach & Opto-Module Low Temperature Flex Components Surface Mount Components (Low Pitch / High Contact Area): Discrete (Active and Passives) IC Chips (Fine Pitch / Low Contact Area): Array Devices Perimeter Devices Die Attach Basic attachment types include: line, area, and point attachments Page 26

28 Technology Gaps & Requirements Nano-Attach Team September 4, 2008

29 Targeted Applications: RF Shield Attach Heat Sink Power Module Heat Sinks Temperature Sensitive SM Components Low Temperature Flex Components Discrete SM (Active and Passives) IC Chips (Fine Pitch / Low Contact Area): Array Devices Perimeter Devices Die Attach Page 28

30 Targeted Applications: Mechanical Requirements Power Heat Sinks Contact Area per Attachment Terminal Heat Sinks RF Shields Low Temperature Flex Components Die Attach Temperature Sensitive Discrete SM SM Components Array Devices Complexity of Attachment (ease of execution) Page 29

31 Targeted Applications: Mechanical Requirements 10 weight (g) / contact (cm 2 ) 1 Power Heat Sinks Die Attach Heat Sinks RF Shields Array Devices Temperature Sensitive SM Components Low Temperature Discrete Flex Components SM 0.1 Decreasing Feature Size Complexity of Attachment (ease of execution) Page 30

32 Targeted Applications: Electrical Requirements Array Devices Complexity of Mechanical Requirements Temperature Sensitive Low Temperature SM Components Flex Components Discrete SM RF Shields Die Attach Complexity of Electrical Requirements (ease of execution) Page 31

33 Targeted Applications: Thermal Requirements Complexity of Mechanical Requirements Temperature Sensitive SM Components Power Heat Sinks Die Attach Heat Sinks Complexity of Thermal Requirements (ease of execution) Page 32

34 Technology Gaps (Mechanical Attachment) Parameters to be used in evaluation Pull strength Shear / Tensile Peel Compression Fatigue Mechanical degradation Thermal degradation Fracture characteristics / fracture mechanics Creep behavior Izod impact test Shock and vibration Drop (Limited or Lack of Experimental Data Currently Available) Page 33

35 Technology Gaps (Mechanical Attachment con t.) Properties as a function of: Contact pressure (distribution and influence of placement force, ) Temperature dependencies Humidity Reattachment / repair (attachment / reattachment dependencies) Other environmental dependencies Page 34

36 Technology Gaps (Mechanical Attachment con t.) Where will these parameters be evaluated? 1. Substrate interface Substrate surface properties (contact composition [tin, gold, copper, indium, ], etc.) Transferred Direct deposit Composite mixture What are cleanliness requirements of the mating surfaces to achieve above properties? 2. Component interface (if needed) Surface roughness of attachment surfaces Component surface properties (contact composition [tin, gold, copper, indium, ], etc.) Page 35

37 Technology Gaps (Mechanical Attachment con t.) Nanotube properties that will affect these parameters 1. Properties of individual nanotubes Young s Modulus Surface characteristics (hydrophobic, hydrophilic, ) Operational environmental stresses (pollution, pressure [hypobaric] sensitivity, ) 2. Properties of nanotube system Dependencies on nanotube interfacial area Density of nanotubes (attachment points) Patterning Hierarchical characteristics Page 36

38 Technology Gaps (Electrical Contact / Conductivity ) Parameters to be used in evaluation 1. Series resistance 2. Maximum current carrying capacity 3. Breakdown voltage 4. Radiation Sensitivity Electromagnetic radiation (RF interference, EMI, EMC, ) Nuclear / Atomic / Magnetic Radiation 5. EOL resistance (simulated accelerated aging) Page 37

39 Technology Gaps (Electrical Contact / Conductivity con t.) Properties as a function of: 1. Contact pressure (distribution and influence of placement force, ) 2. Contact area 3. Temperature 4. Humidity 5. Frequency response 6. Repeated attach/reattach cycles (attachment / reattachment dependencies) 7. Other environmental dependencies Page 38

40 Technology Gaps (Electrical Contact / Conductivity con t.) Where will these parameters be evaluated? 1. Substrate interface / surface properties Contact composition [tin, gold, copper, indium, ] What are cleanliness requirements of the mating surfaces to achieve above properties? Sensitivity to cleaning chemistry 2. Component interface Surface roughness of attachment surfaces Is there a limiting layer if intermediate layer(s) is(are) needed? Contact composition [tin, gold, copper, indium, ] Page 39

41 Technology Gaps (Electrical Contact / Conductivity con t.) Nanotube properties that will affect these parameters 1. Properties of individual nanotubes Growth environmental parameters» Diameter (Single-walled, multi-walled)» Chirality - chiral angle and diameter (semiconducting or metallic)» Surface characteristics (hydrophobic, hydrophilic, ) Operational environmental stresses (e.g. carbon nanotubes are studied for their chemical sensor capabilities) 2. Properties of nanotube system Dependencies on nanotube interfacial area and structure Density of nanotubes (attachment points) Page 40

42 Technology Gaps (Thermal Contact / Conductivity) Parameters to be used in evaluation 1. Thermal resistance (z direction) 2. Thermal conductivity (xy direction) 3. Thermal capacitance (transient behavior) Properties as a function of: 1. Contact pressure (distribution and influence of placement force, ) 2. Contact area 3. Temperature 4. Humidity 5. Repeated attach/reattach cycles (attachment / reattachment dependencies) 6. Other environmental dependencies Page 41

43 Parameters: Mechanical 1. Pull strength Shear /Tensile Peel Compression 2. Fatigue Mechanical degradation Thermal degradation 3. Fracture characteristics / fracture mechanics Creep behavior Izod impact test Shock and vibration Drop 4. Other parameters A. Contact pressure (distribution and influence of placement force, ) B. Temperature dependencies C. Humidity D. Reattachment / repair (attachment / reattachment dependencies) E. Other environmental dependencies F. As a function of others Page 42

44 Parameters: Electrical 1. Series resistance 2. Maximum current carrying capacity 3. Breakdown voltage 4. Radiation sensitivity Electromagnetic radiation (RF interference, EMI, EMC, ) Nuclear / Atomic / Magnetic Radiation 5. EOL resistance (simulated accelerated aging) 6. Other parameters A. Contact pressure (distribution and influence of placement force, ) B. Contact area C. Temperature D. Humidity E. Frequency response F. Repeated attach/reattach cycles (attachment / reattachment dependencies) G. Other environmental dependencies (pressure, atmospheric conditions, ) H. As a function of others Page 43

45 Parameters: Thermal 1. Thermal resistance (z direction) 2. Thermal conductivity (x-y direction) 3. Thermal capacitance (transient behavior) 4. Other parameters A. Contact pressure (distribution and influence of placement force, ) B. Contact area surface roughness C. Temperature D. Humidity E. Repeated attach/reattach cycles (attachment / reattachment dependencies) F. Other environmental dependencies G. As a function of others Page 44

46 Technology Impact Nano-Attach Team 4 September 2008

47 Targeted Applications: Mechanical Requirements Power Heat Sinks Contact Area per Attachment Terminal Heat Sinks RF Shields Low Temperature Flex Components Die Attach Temperature Sensitive Discrete SM SM Components Array Devices Complexity of Attachment (ease of execution) Page 46

48 Targeted Applications: Mechanical Requirements 10 weight (g) / contact (cm 2 ) 1 Power Heat Sinks Die Attach Heat Sinks RF Shields Array Devices Temperature Sensitive SM Components Low Temperature Discrete Flex Components SM 0.1 Decreasing Feature Size Complexity of Attachment (ease of execution) Page 47

49 Targeted Applications: Electrical Requirements Array Devices Complexity of Mechanical Requirements Temperature Sensitive Low Temperature SM Components Flex Components Discrete SM RF Shields Die Attach Complexity of Electrical Requirements (ease of execution) Page 48

50 Targeted Applications: Thermal Requirements Complexity of Mechanical Requirements Temperature Sensitive SM Components Power Heat Sinks Die Attach Heat Sinks Complexity of Thermal Requirements (ease of execution) Page 49

51 Compared to solder, using Nano-Attach Technology Would Simplify Assembly Enhance / Improve Functionality Economic Benefits RF Shield Neutral Worse-Neutral (frequency dependant) Worse Neutral Heat Sink (low power) Neutral Better Better Neutral Better (size dependant) Power Module Heat Sinks Neutral Better Better Better Temperature Sensitive SM Components Better Worse Better (application dependant) Neutral Better Low Temperature Flex Components Neutral Better (pitch dependant) Neutral Better Low Moderate Discrete SM Worse Worse Neutral Worse Neutral Array Devices Worse Neutral (planarity dependant) Worse Neutral Better (capability to repair) Die Attach Neutral Better Neutral Better Neutral Better Legend: Worse, Neutral, Better Page 50

52 Generic Assembly Cost Model: Traditional Soldering Screen Print Pick & Place Mass Reflow Selective Soldering PWBs solder paste components solder paste components Capital Investment (Equipment): Screen print Pick & Place Mass Reflow Selective Soldering Materials: Solder paste PWBs Components Page 51

53 Generic Assembly Cost Model: Nano-Attach Screen Print Pick & Place Mass Reflow Selective Soldering PWBs X X X solder Xpaste components solder components X X paste Capital Investment (Equipment): Pick & Place Materials: Components PWBs with nanostructures Assumption: start with best case scenario, work back from there Page 52

54 Generic Assembly Cost Model: Comparison Transition from Traditional Solder to Nano-Attach Technology Elimination of: Addition of: Capital Investment (Equipment): Screen print Mass Reflow Selective Soldering Materials: PWBs with nanostructures Materials: Solder paste Page 53

55 Phase 2 Attributes Nano-Attach Team September 4, 2008

56 Parameters to be used in evaluation Pull strength Shear /Tensile Peel Compression Fatigue Mechanical degradation Technology Gaps Summary Thermal degradation Fracture characteristics / fracture mechanics Creep behavior Izod impact test Shock and vibration Drop Properties as a function of: Contact pressure (distribution and influence of placement force, ) Temperature dependencies Humidity Reattachment / repair (attachment / reattachment dependencies) Other environmental dependencies Mechanical Attachment Overview Where will these parameters be evaluated? Substrate interface Substrate surface properties (contact composition [tin, gold, copper, indium, ], etc.) Transferred Direct deposit Composite mixture What are cleanliness requirements of the mating surfaces to achieve above properties? Component interface (if needed) Surface roughness of attachment surfaces Component surface properties (contact composition [tin, gold, copper, indium, ], etc.) Nanotube properties that will affect these parameters Properties of individual nanotubes Young s Modulus Surface characteristics (hydrophobic, hydrophilic, ) Operational environmental stresses (pollution, pressure [hypobaric] sensitivity, ) Properties of nanotube system Dependencies on nanotube interfacial area Density of nanotubes (attachment points) Patterning Hierarchical characteristics Page 55

57 Technology Gaps Summary Electrical Contact / Conductivity Overview Parameters to be used in evaluation 1. Series resistance 2. Maximum current carrying capacity 3. Breakdown voltage 4. Radiation sensitivity Electromagnetic radiation (RF interference, EMI, EMC, ) Nuclear / Atomic / Magnetic Radiation 5. EOL resistance (simulated accelerated aging) Properties as a function of: 1. Contact pressure (distribution and influence of placement force, ) 2. Contact area 3. Temperature 4. Humidity 5. Frequency response 6. Repeated attach/reattach cycles (attachment / reattachment dependencies) 7. Other environmental dependencies (pressure, atmospheric conditions, ) Where will these parameters be evaluated? 1. Substrate interface / surface properties 2. Contact composition [tin, gold, copper, indium, ] 3. What are cleanliness requirements of the mating surfaces to achieve above properties? 4. Sensitivity to cleaning chemistry 5. Component interface 6. Surface roughness of attachment surfaces 7. Is there a limiting layer if intermediate layer(s) is(are) needed? 8. Contact composition [tin, gold, copper, indium, ] Nanotube properties that will affect these parameters 1. Properties of individual nanotubes 2. Growth environmental parameters Diameter (Single-walled, multi-walled) Chirality - chiral angle and diameter (semiconducting or metallic) Surface characteristics (hydrophobic, hydrophilic, ) 3. Operational environmental stresses (e.g. carbon nanotubes are studied for their chemical sensor capabilities) 4. Properties of nanotube system 5. Dependencies on nanotube interfacial area and structure 6. Density of nanotubes (attachment points) Page 56

58 Technology Gaps Summary Parameters to be used in evaluation 1. Thermal resistance (z direction) 2. Thermal conductivity (x-y direction) 3. Thermal capacitance (transient behavior) Properties as a function of: 1. Contact pressure (distribution and influence of placement force, ) 2. Contact area surface roughness 3. Temperature 4. Humidity 5. Repeated attach/reattach cycles (attachment / reattachment dependencies) 6. Other environmental dependencies Where will these parameters be evaluated? 1. Substrate interface / surface properties Contact composition / surface material [tin, gold, copper, indium, ] Cleanliness requirements of the mating surfaces to achieve above properties Sensitivity to cleaning chemistry 2. Component interface Surface roughness of attachment surfaces Is there a limiting layer if intermediate layer(s) is(are) needed? Contact composition / surface material [tin, gold, copper, indium, ] Thermal Contact / Conductivity Overview Nanotube properties that will affect these parameters 1. Properties of individual nanotubes Diameter (Single-walled, multi-walled) Chirality - chiral angle and diameter (semiconducting or metallic) Surface characteristics (hydrophobic, hydrophilic, ) Operational environmental stresses (e.g. carbon nanotubes are studied for their chemical sensor capabilities) 2. Properties of nanotube system Dependencies on nanotube interfacial area and structure Density of nanotubes (attachment points) Dependency on nanotube mix (semiconducting vs. metallic) Density of conductive particles (dispersion uniformity) Page 57

59 Information Needed to Develop Evaluation Vehicle Nano-material Structure (Nanostructure Level) Identify available material systems (i.e. carbon nanotube based, polymer based, composite, etc.) Which material system(s) should we choose to explore / evaluate? Application spaces [prioritized listing] Mechanical attachment (component to board) (essential) Electrical contact / conductivity (interfacial resistivity) Thermal contact / conductivity (interfacial resistance) Electromechanical (e.g. resettable / programmable fuse, electrically actuated contact, etc ) Both electrical and thermal (possible interactions, positive and/or negative) Page 58

60 Information Needed to Develop Evaluation Vehicle Layer Structure (System Level) Investigating material layer structures in Phase 2 is essential in developing the device prototypes for Phase 3 where the nanostructures will need to be incorporated into the component/board pads Is an intermediate layer necessary and for what material systems? Consider the deposition or formation on a pre-existing contact structure (mechanical, electrical, and/or thermal) implies no intermediate layer If the nanostructures need an intermediate layer (carrier), characterizing the nanostructure and the intermediate layer as an unit will be critical (single and/or double sided nano-structures) How does layer structure affect the performance (i.e. electrical, thermal, mechanical) of the nanostructure system? Investigating interfacial performance of mechanical, thermal, and electrical behavior of joint structures with common electronic packaging materials Page 59

61 Relative Performance of Materials Polymers Carbon Nanotubes Embedded Polymers Semiconductor / Metallic Nanowires Mechanical strength low - moderate high low - moderate moderate Electrical conductivity low high moderate moderate - high Thermal conductivity low - moderate high moderate moderate - high Density low - moderate high low - moderate moderate - high Ease of fabrication moderate moderate difficult / research moderate - difficult Electronic assembly Carbon nanotubes (CNTs) may provide best path Page 60

62 Baseline Material Properties Comparison Common Material Systems Performance Carbon Nanotubes Tensile Strength High-strength steel alloys ~2 GPa ~63 GPa [1] Current Carrying Capacity Copper wires ~1 x 10 6 A/cm 2 up to 1 x A/cm 2 [2] Thermal Diamond 3,320 W/m*K up to 6,000 W/m*K [3] [1] M.F. Yu, O. Lourie, M.J. Dyer, K. Moloni, T.F. Kelly, R.S. Ruoff, Strength and Breaking Mechanism of Multiwalled Carbon Nanotubes Under Tensile Load, Science, 287, 637 (2000). [2] B.Q. Wei, R. Vajtai, and P.M. Ajayan, Reliability and Current Carrying Capacity of Carbon Nanotubes, Appl. Phys. Lett., 79, 1172 (2001). [3] J. Hone, M. Whitney, C. Piskoti, and A. Zettl, Thermal Conductivity of Single-Walled Carbon Nanotubes, Phys. Rev. B, 59, R2514 (1999). Page 61

63 Evaluation Vehicle Assumptions Evaluation Vehicle A (Direct Growth) Carbon nanotube based system Vertically aligned nanostructures Nanostructures directly grown on surface Substrates: Si and Cu Single-sided adhesion scheme (i.e. Gecko like) Adhesion requires only a preload force Sample sizes cover spectrum of dimensions Need repeatable contact area application Need strong adhesion between growth substrate and nanostructures Page 62

64 Evaluation Vehicle Assumptions (con t.) Evaluation Vehicle B (Transfer) Carbon nanotube based system Vertically aligned nanostructures Nanostructures grown in a separate process (growth substrate irrelevant) Nanostructures transferred onto contact (i.e. stamping process) Single-sided adhesion scheme (i.e. Gecko like) Adhesion requires only a preload force Sample sizes cover spectrum of dimensions Need repeatable contact area application Need something easy to peel (substrate irrelevant), to separate from growth substrate Transfer Technology Papers [1] A. Kamar, V.L. Pushparaj, S. Kar, O. Nalamasu, P.M. Ajayan, R. Baskaran, Contact Transfer of Aligned Carbon Nanotube Arrays onto Conducting Substrates, Appl. Phys. Lett., 89, (2006). [2] L. Zhu, J. Xu, Y. Xiu, D.W. Hess, and C.P. Wong, Controlled Growth of Well-Aligned Carbon Nanotubes and Thier Assembly, Adv. Pack. Mat. Int. Sym., 123 (2006). Page 63

65 Test Coupon: Mechanical 2 Mounting hole Substrate 1 Test Material Nanostructure material Top View Stack-up View Nanostructure material: Evaluation Vehicle A: CNTs grown on substrate Evaluation Vehicle B: CNTs transferred onto dummy substrate Test pad materials: flash gold, Cu, intentionally oxidized Cu, Cu (OSP coating), Si, printed conductor (AgPt, AgPd) on ceramic, Al (heatsinks), and anodized Al. Page 64

66 Test Coupon: Electrical 2 Measurement Substrate 1 Test Material Nanostructure material Mounting hole Top View Stack-up View Page 65

67 Evaluation Module Design Parameters: Electrical Coupon Size: Pad: Feature sizes (device dependence) Suggest coupon as initial test vehicle Coupon size: 1 x 2 maximum Use two coupons per attachment (asymmetrical design) Need one pad on coupon for nano attach material and one trace to a continuity pad/via. Design coupons in an array with various pad diameters May need a thermal via in test pad area Pad Material: (depends on temperature of nano attach) 1 st choice if FR4 2 nd choice is Alumina (ceramic hybrid material) Surface finish: ENIG, Im-Sn or OSP depending on nano material requirements Alumina would use PbAg pads or be plated with NiAu Page 66

68 Test Coupon: Thermal 8 mm Laser Beam Substrate 8 mm Nanostructure Material Nanostructure material Top View Stack-up View Total thickness is 2mm + 2mm = 4 mm Different materials substrates can be used if the thermal conductivity is known. Page 67

69 Temperature Thermal Conductivity Measurement: Using Laser Flash Measuring thermal diffusivity ( ) and calculate thermal conductivity: k = *Cp* Sample size: 8mm x 8mm about 2mm thick Page 68

70 Thermal Conductivity Measurement: One Example TIM = tot ( x/k) top - ( x/k) bottom Laser flash is useful for quantifying effects of voiding on thermal impedance Page 69

71 contacts: Jim McElroy Bob Pfahl