InMold Electronics

John Crumpton

Flexible Hybrid Electronics, MEMS and Sensors in the Automotive Industry and Related Transportation Markets Workshop 9/13/2017

Agenda

– What is InMold Electronics

– Enabling Technology

– Paste Constituents & Processing Steps

– DuPont’s Technical Approach – Collaboration

– Stretch Characterization

– Reliability Testing

2

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)

What is InMold Electronics (IME)?

Conventional Ag ME602 (5043)

How is this achieved:

- development of stretchable inks which can

withstand the high temperature processes

3

IME In ‘3 Easy Steps’

From paste to functional device !

(1) Printing (2) Thermoforming (3) Over-Molding

Thermoformed Conventional Ag ME602 (5043)

Enabling Technology

4

Enabling Technology - Paste Constituents & Key Features

Polymer

‘Filler’

Solvent

Elastic/Stretchable

Good adhesion to PC

Withstands high temperatures

Solubilizes polymer

Good screen print properties

Compatible with PC & graphic inks

Conductor Ag, Carbon...etc

Dielectrics 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?

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

Design

Good aesthetics

Lower cost

Reliable

No movable parts

3D Electronics

Uniqueness

Simplified Builds

Thermoformable

Design aspect should not to be underestimated

Allowing novel designs for enhanced product appeal

Less space

Lighter

Automotive

Lighter

Less space

Design freedom

Reliability

Ease of assembly

Ford Overhead Console

Aviation Industry

Lower weight

Fewer cables

This technology is ideally suited for the integration of Capacitive Switches and interconnecting tracks

there are potential IME benefits for various Industries

Appliance Industry

Lower cost

Design freedom

6

7

Enabling Technology – Automobiles Past

8

Enabling Technology – Automobiles Current

Enabling Technology – Automobiles Future

9

10

Enabling Technology – Design Benefits

Broad Outline of Processing Steps

Common Process Flow

Film inmold (Film-insert molding)

Thermoforming Cut & trim Injection moldingDevice assembly Completion

PC / Other film

~ 250-350 umOven

Vacuum or high air pressure

> 150 ºC Parts

& components

PC

Drying

~ 275-325°C

Design &

Electronics

Screen printing

Ag / Functional inks Protection layer*Substrate Dry / Cure

Graphic inks

11

Processing (1) & Collaboration/Partners (2), (3)

Film inmold (Film-insert molding)

Thermoforming Cut & trim Injection moldingDevice assembly Completion

PC / Other film

~ 200-300 umOven

Vacuum or high air pressure

> 150 ºC Parts

& components

PC

Drying

~ 275-325°C

Design & Electronics

Screen printing

Ag / Functional inks Protection layer*Substrate Dry / Cure

Graphic inks

Collaboration 2

Collaboration 3

12

Processing 1

Processing 1

Multilayer Structure

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

Screen Printing – guidance & details

can be obtained from the data sheets

- composition properties and processing

information is included

Drying

A critical processing parameter

- It’s important to ensure complete solvent removal

(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

• Looking at the spread of resistance values per drying group:

Box Oven - Drying time needed approx 20min

With fan assisted ventilation

Good drying

How to Establish the Box Oven Profile

10 parts separately printed &

dried for each drying condition

ME602

14

15

1

10

100

1000

10000

100000

1000000

10000000

0.0 20.0 40.0 60.0 80.0 100.0

Re

sist

ance

[O

hm

]

Time [s]

Time-Resistance curve all pastes @ 120°C

ME101

ME602

ME603

200528-3B

200528-3C

200528-3BC

200528-3G

200528-3H

200528-3GH

200630-3A

Belt Oven Drying ME60X Ag and R&D Samples

16

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

Design & Electronics

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

17

Enabling Technology – Design Benefits

Moving the user interface closer to the embedded electronics

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

Covestro (Bayer) - PC

Sabic, - PC

DuPont Teijin Films - Formable PET

Graphic Inks

Proell - mostly EU

- customer projects

Nazdar - mostly USA

19

Substrates & Graphic Inks

Courtesy of Tactotek

Working with substrates & graphic inks to resolve show-through (witness marks)

Collaboration 3 - Thermoforming

20

9

8

7

6

5

4

3

2

1

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

Resistance Resistance

Sample K1 Sample K2

Forming Test Pattern

Tracks 1–9 printed over

different geometries &

radii

Tracks 1–9 – Resistance before & after thermoforming

K1- Lower resistance increase K2- 2x Open Circuits

Formech IMD600

Vacuum forming

Niebling

High pressure

forming

Niebling - Heat map demonstrating heat distribution

Example of Thermoformed Parts

High pressure forming

Applying heat & pressure

- shapes the printed film

to the 3D molding tool

Collaboration 3a – Thermoforming Example

21

ME772

Poly-Carbonate

5043

5043

ME772 ME772

Poly-Carbonate

5043170A

Various Test Areas

Cross-overs Dielectric Under-Print Dielectric Over-Print

Fine Line Printing

As-Printed ME602 Resistance

Thermoformed ME602 Resistance

Customer Sintex Tooling

- parts were thermoformed

DuPont tested at 85ºC/85%RH

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

Collaboration 3b – Tactotek Example

Stretch Characterization – Cone Design

Cone shape design used to check progressive stretch performance

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

Printed tracks = 1.0mm, 0.5mm, 0.2mm

23

15

10

5

DrawDepthmm

% Stretch

Cell Values

Y Direction

% Stretch

Cell Values

X Direction

Stretch Characterization - Elongation & Resistance

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

0

200

400

600

800

1000

1200

1400

1600

1800

2000

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

Res

ista

nce

Incr

ease

(Ω

)

Stretch Values X (%) & Draw Depth Z (mm)

ME602 Thermoformed Resistance vs 3D Stretch

24

Design Incorporated Various Test Areas

Interdigitated Capacitance Design

LED’s attached with ME901

conducting adhesive

Carbon over print

Cross-overs

Under/over print

Cone

25

Test Results – 2400hrs at 85⁰C/85%RH

Printed tracks

= 1.0mm, 0.5mm, 0.2mm

ME602 Ag Conductor

- Good 85⁰C/85%RH performance through to 1500hrs

26

0

50

100

150

200

250

300

350

400

450

500

0 200 400 600 800 1000 1200 1400 1600

Re

sist

ance

(m

Ω/s

q)

Time (Hrs)

Resistance vs Time with increasing conductor stretch ME602 - 1mm track width

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

Reliability Test Results - Summary

Thermal Cycling

-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

Accelerated Environmental Ageing 85ºC/85%RH

Functional LEDs following

1500hrs at 85⁰C/85%RH27

LED’s attached with ME901

conducting adhesive

Interdigitated Capacitance Design

0

50

100

150

200

250

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

Res

ista

nce

(m

Ω/s

q)

Time (Hrs)

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

28

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

29

12A 12D ME901TraditionalThermoset

Flex Adhesion – LEDs bent around 1 inch rod

New applications require continued development of material

Flex Testing of Conductive Adhesives

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

31

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

Example of Construction and Paste Options

32

Transparent

Conductor

ME801

Interconnecting tracks

ME602/ME603 Ag

Conducting

Adhesive

ME901

Dielectric

- over-print protection ME772

Solvent based

Dielectric

for x-overs

ME775/ME776

Translucent

Conductor

ME802

LED Attach

ME901

Dielectric

- under-print ME775/ME776

RFID – NFC

- Antenna ME101

Thank you,

John Crumpton DuPont Photovoltaic & Advanced Materials Wilmington, DE 19805