Flexible Hybrid Electronics, MEMS and Sensors in the Automotive Industry and Related Transportation Markets Workshop 9/13/2017 InMold Electronics John Crumpton
Agenda What is InMold Electronics Enabling Technology Paste Constituents & Processing Steps DuPont s Technical Approach Collaboration Stretch Characterization Reliability Testing 2
What is InMold Electronics (IME)? General concept outlined: A printed electronic circuit, which has undergone a thermoforming and injection molding process. The circuit remains functional as the conducting tracks contour the 3D shape. The circuitry may or may not have mounted components. IME is a natural fit with existing processes - IMD/FIM (Film Insert Molding) - Base technology from the 1990s - Essentially combines film, graphics and electronics, in one, forming a 3D fully integrated functional electronic device (with the option of adding components) How is this achieved: - development of stretchable inks which can withstand the high temperature processes Conventional Ag ME602 (5043) 3
IME In 3 Easy Steps From paste to functional device! (1) Printing (2) Thermoforming (3) Over-Molding Enabling Technology Thermoformed Conventional Ag ME602 (5043) 4
Enabling Technology - Paste Constituents & Key Features Polymer Solvent Elastic/Stretchable Good adhesion to PC Withstands high temperatures Solubilizes polymer Good screen print properties Compatible with PC & graphic inks Filler Conductor Dielectrics Ag, Carbon...etc different for under/over print, cross-over Functional Ink Balance of conductivity & stretchability Balance of viscosity, good printing properties Compatibility with substrates / graphic inks / other pastes from the IME family 5
InMold Electronics Why the big fuss? This technology is ideally suited for the integration of Capacitive Switches and interconnecting tracks there are potential IME benefits for various Industries Ford Overhead Console Aviation Industry Lower weight Fewer cables Lower cost Good aesthetics Lighter Appliance Industry Lower cost Design freedom Thermoformable 3D Electronics Uniqueness Design Simplified Builds Reliable No movable parts Less space Automotive Lighter Less space Design freedom Reliability Ease of assembly Design aspect should not to be underestimated Allowing novel designs for enhanced product appeal Why the big fuss? It s a versatile technology which can be used in a number of different markets, to provide various advantages, over conventionally built products 6
Enabling Technology Automobiles Past 7
Enabling Technology Automobiles Current 8
Enabling Technology Automobiles Future 9
Enabling Technology Design Benefits 10
Broad Outline of Processing Steps Design & Electronics Common Process Flow Substrate Graphic inks Screen printing Ag / Functional inks Protection layer * Dry / Cure PC / Other film ~ 250-350 um Drying Oven Film inmold (Film-insert molding) Thermoforming Cut & trim Injection molding Device assembly Completion Vacuum or high air pressure > 150 ºC ~ 275-325 C Parts & components PC 11
Processing (1) & Collaboration/Partners (2), (3) Design & Electronics Processing 1 Collaboration 2 Substrate Graphic inks Screen printing Ag / Functional inks Protection layer * Dry / Cure PC / Other film ~ 200-300 um Drying Oven Collaboration 3 Film inmold (Film-insert molding) Thermoforming Cut & trim Injection molding Device assembly Completion Vacuum or high air pressure > 150 ºC ~ 275-325 C Parts & components PC 12
Processing 1 Functional pastes are screen printed on a substrate of choice, with/without graphic inks. - The pastes are dried to remove the solvents. - Multilayers are fabricated by repeating the print/dry steps Multilayer Structure Drying A critical processing parameter - It s important to ensure complete solvent removal Screen Printing guidance & details can be obtained from the data sheets - composition properties and processing information is included (1) Temperature < 120⁰C for PC (best 110⁰C to 120⁰C) (2) Time - dependent on drier efficiency (3) Air - Good airflow is essential 13
Box Oven / Static Drying ME60 Ag How to Establish the Box Oven Profile ME602 With fan assisted ventilation 10 parts separately printed & dried for each drying condition Good drying Looking at the spread of resistance values per drying group: Box Oven - Drying time needed approx 20min 14
Belt Oven Drying ME60X Ag and R&D Samples Resistance [Ohm] 10000000 1000000 100000 10000 1000 100 10 1 Time-Resistance curve all pastes @ 120 C 0.0 20.0 40.0 60.0 80.0 100.0 Time [s] ME101 ME602 ME603 200528-3B 200528-3C 200528-3BC 200528-3G 200528-3H 200528-3GH 200630-3A 15
Design & Electronics Self capacitance / Mutual capacitance Touch Sensing Electronics Has been commercial for many years. Semiconductor companies have considerable documentation, design guides and support. - Texas Instruments - Microchip-Atmel - Cypress Semiconductors - Freescale DuPont does not participate in the supply of electronic components or design of the Capacitive Touch Sensors Design guidelines for Capacitive Switches are readily available from various Semiconductor manufacturers e.g. Microchip-Atmel 16
Enabling Technology Design Benefits Moving the user interface closer to the embedded electronics 17
Collaboration 2 Bayer (Covestro) Example Joint paper was presented at Lope-C 2012 - we investigated the capabilities of new formable Ag - we checked various radii and shapes and assessed performance by measuring resistance Experimental Parameters The substrate was Polycarbonate. - Bayer Makrofol DE was used. Various advantages which include high heat resistance, toughness, elasticity over a wide temperature range, good stiffness and excellent electrical insulation properties. High Pressure Forming (HPF) method was used - Niebling semi-automatic SAMK 400 equipment. The film was formed at temperature of 160 C-170 C (for 8s) with compressed air pressure at 100 bar 18
Collaboration 2a Substrates & Graphic Inks To provide a good IME solution to the Industry, various challenges exist: - from materials and processes to equipment used Collaboration with technology leaders and specialized innovators is therefore essential Substrates & Graphic Inks Substrates Covestro (Bayer) - PC Sabic, - PC DuPont Teijin Films - Formable PET Courtesy of Tactotek Graphic Inks Proell - mostly EU - customer projects Nazdar - mostly USA Working with substrates & graphic inks to resolve show-through (witness marks) 19
Collaboration 3 - Thermoforming Applying heat & pressure - shapes the printed film to the 3D molding tool 9 6 8 5 7 4 Forming Test Pattern Tracks 1 9 printed over different geometries & radii 3 1 2 High pressure forming Formech IMD600 Vacuum forming Example of Thermoformed Parts Tracks 1 9 Resistance before & after thermoforming Sample K1 Sample K2 Resistance Resistance Track Before After Before After nos Forming Forming (Ω) (Ω) (Ω) (Ω) 9 7.0 6.8 7.0 8.1 8 5.4 7.8 5.6 11.0 7 6.8 12.1 6.7 O/C 6 6.4 14.6 6.9 20.0 5 5.2 12.8 5.5 O/C 4 6.0 5.0 6.4 6.7 3 6.6 10.1 6.7 16.8 2 5.5 10.9 5.7 28.3 1 6.2 17.4 6.3 O/C K1- Lower resistance increase K2-2x Open Circuits Niebling High pressure forming Niebling - Heat map demonstrating heat distribution 20
Collaboration 3a Thermoforming Example Customer Sintex Tooling - parts were thermoformed DuPont tested at 85ºC/85%RH As-Printed ME602 Resistance Various Test Areas Fine Line Printing Thermoformed ME602 Resistance 5043 ME772 ME772 ME772 5043 Poly-Carbonate 5043 170A Poly-Carbonate Cross-overs Dielectric Under-Print Dielectric Over-Print 21
Collaboration 3b Tactotek Example Contents Cone Design for stretch testing Stretch vs Resistance measurements for improved characterisation New technology need reliability data Summary of environmental testing at 85⁰C/85%RH & thermal cycling from -40⁰C to +85⁰C 22
Stretch Characterization Cone Design Cone shape design used to check progressive stretch performance 15 10 % Stretch % Stretch 5 Printed tracks = 1.0mm, 0.5mm, 0.2mm Cell Values X Direction Cell Values Y Direction Draw Depth mm Reference grid Thermoformed grid Stretch measurements calculated from printed grid: Stretch was in 3 dimensions measured as x, y and z (draw depth) - in y direction < 5% - in x direction, progressive increase - in z direction, progressive draw depth 23
Stretch Characterization - Elongation & Resistance Resistance Increase (Ω) Cone shape design used to check progressive stretch performance Conductor = ME602 Ag (5043) Resistance increase with progressive stretch for 1mm tracks Printed tracks = 1.0mm, 0.5mm, 0.2mm ME602 Thermoformed Resistance vs 3D Stretch 2000 1800 1600 1400 1200 1000 800 600 400 200 0 Track # A A0 A9 A8 A7 A6 A5 A4 DrawDepth mm 0 2.5 5.0 7.5 9.5 12.0 14.0 16.0 Stretch % 0 25 25 30 35 40 45 45 Stretch Values X (%) & Draw Depth Z (mm) 24
Design Incorporated Various Test Areas Under/over print LED s attached with ME901 conducting adhesive Cone Carbon over print Cross-overs Interdigitated Capacitance Design 25
Test Results 2400hrs at 85⁰C/85%RH Resistance (mω/sq) Resistance vs Time with increasing conductor stretch ME602-1mm track width 500 450 400 350 300 250 200 No Stretch/ No Draw Depth Stretch 25% D/depth 2.5mm Stretch 25% D/depth 5.0mm Stretch 30% D/depth 7.5mm Stretch 35% D/depth 9.5mm Stretch 40% D/depth 12.0mm Printed tracks = 1.0mm, 0.5mm, 0.2mm 150 100 50 0 0 200 400 600 800 1000 1200 1400 1600 Time (Hrs) ME602 Ag Conductor - Good 85⁰C/85%RH performance through to 1500hrs 26
Resistance (mω/sq) Reliability Test Results - Summary Accelerated Environmental Ageing 85ºC/85%RH 250 200 ME602-1mm track width - Accelerated Ageing at 85⁰C/85% Resistance vs Time for No stretch & 25% stretch No Stretch/ No Draw Depth Stretch 25% D/depth 2.5mm ME602 Ag Conductor - Good 85⁰C/85RH performance through to 2400hrs 150 Interdigitated Capacitance Design 100 50 0 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 Time (Hrs) Thermal Cycling LED s attached with ME901 conducting adhesive -40⁰C to +85⁰C, Cycles 2hr cycle with 10' hold 0 100 250 400 ME602 Capacitance (pf) 1.6 1.5 1.4 1.5 ME603 Capacitance (pf) 1.6 1.5 1.3 1.5 Functional LEDs following 1500hrs at 85⁰C/85%RH 27
Reliability Testing - Component Attach Customers want to attach LEDs and other components on 2D sheets and then thermoform Traditional conductive Adhesives have high adhesion but poor flexibility 28
Flex Adhesion LEDs bent around 1 inch rod Flex Testing of Conductive Adhesives 12A 12D ME901 Traditional Thermoset New applications require continued development of material 29
Summary / Conclusions New stretchable ink technology, which fits well into existing IMD/IML processes, provides the ability to create novel and fully integrated functional 3D circuitry This technology is referred to as InMold Electronics It s a versatile technology, ideally suited to Capacitive Switch applications, particularly for Automotive Surfaces and Appliances A comprehensive suite of compatible inks have been developed which include conductors, dielectrics, adhesives and transparent conductors Accelerated environmental test performance at 85ºC/85%RH and thermal cycling (from -40ºC to +85ºC) has demonstrated a robust and reliable technology 30
IME Product Portfolio Product Composition Rs mω/ /25um Comments ME602 Ag ~ 45 PC friendly & for over-printing on Graphic inks ME603 Ag ~35 PC compatible & improved Ag show-through (on Proell inks) ME60x New - In development ME101 Ag 15 RFID NFC antenna ME10x New In-development ME703 Dielectric Under-print High K (improved S/N ratio for Capacitance switching) ME772 Dielectric Over-print protection - solvent base ME777 New over-print with UV blocking additive. In scale-up ME774 Dielectric x-overs/multilayer, UV cure low elongation areas > 1.2KV BDV ME775 Dielectric x-overs, solvent base 3-4 layers (25um), print on graphics inks ME776 Dielectric x-overs, solvent base 3-4 layers improved PC compatibility & bowing ME77x New In-development ME801 T/Conductor < 500 Ω/ Transparent Conductor High LED/light transmission >90% ME802 T/Conductor 3-4 KΩ/ /25um Translucent Conductor lower cost, higher resistance ME901 Ag Adhesive 60 1 component stretchable ME80x New In-development ME201 Carbon 100 Ω/ /25um Overprint for connectors & to inhibit Ag migration Selector Guide & Data Sheets - Inmoldelectronics.dupont.com 31
Example of Construction and Paste Options Dielectric - over-print protection ME772 Solvent based Dielectric for x-overs ME775/ME776 Transparent Conductor ME801 Conducting Adhesive ME901 Translucent Conductor ME802 RFID NFC - Antenna ME101 LED Attach ME901 Dielectric - under-print ME775/ME776 Interconnecting tracks ME602/ME603 Ag 32
Thank you, John Crumpton DuPont Photovoltaic & Advanced Materials Wilmington, DE 19805