1. Conformal Inkjet Direct Write on Aerospace Components Industrial Doctorate Centre and BAE Systems Mau Yuen Chan Prof. Alan Champneys Dr. Jagjit Sidhu Dr. Paul Warr

2. This Presentation • What is direct write (DW)? • Differences in method to traditional lithography • Benefits of DW? • What advantages it brings • The challenges faced during the study • The DW system

3. Direct Write • A freeform patterning and deposition technique • Completes patterning and deposition simultaneously • Encompasses different deposition techniques • Droplet • Laser • Flow • Tip • No single ‘perfect’ technique • Innovative applications

4. Comparison to Convention • Lithography • Requires the use of masks • Large material wastage • Changes to designs costly • Etch step limits substrate material type • Substrates must be relatively planar • High capital cost • Direct Write • Freeform patterning • Low material wastage • Mass customisation • Variety of substrate materials possible • Substrates can be non-planar • Lower capital costs

5. Benefits for • Benefits: • Higher material efficiency • Mass customisation • Increased design freedom • Integrated functionality • COPE Project • Replacing electronic wiring with DW solution

6. The Helmet Shell • Aerospace Helmet used by pilots • Recognised as the most advanced helmet in the world • Undergoes further development to keep competitiveness • Even during the project study • Features: • Complex concave Shape • Carbon fibre substrate • Head tracking system; composed of LEDs and flexible connectors for wiring

7. The DW Process Design Execution Evaluation

8. Challenges

9. Inks and substrates Electroplating Multi-discipline Mechatronics Physical Chemistry Printing system Multi-layers Electrical Engineering Mechanical Engineering Computer Science Control Systems Electrochemistry Post-processing Thermal Science & Physical Chemistry DW printed component Business

10. MasterCam® • The ‘creative brain’ • MasterCam is a CAD/CAM design software • Originally a software program for milling applications • Used to manipulate CAD models and design DW tracks • Output: Movement scripts for the motion controller

11. 5-axis Motion Controller • The ‘arm’ • A motion control robot with five degrees of freedom giving it a large work envelop • All tools mounted onto working face • Required mechanical integration • Precision controlled (0.001mm accuracy) 150µm 100µm 50µm

12. Inkjet Printer • The ‘pen’ • Single nozzle jetting device (MicroFab) • Inks used • Polymer dielectric ink • Silver conductive nanoparticle ink • Can jet many materials • May require post-processing to functionalise

13. Bluewave® System • UV energy delivery system • Required for curing polymer dielectric ink • Controllable and localised output • Curing regime affects silver behaviour

14. iCure™ System • Thermal spot delivery system for sintering • Delivers focussed broad-band optical energy • + Controlled thermal exposure • + Superior electrical properties than oven sintering • - Difficulty on thermally conductive substrates • - Inks needed to be modified to match process

15. Thermal Damage • 4-point bend test used to investigate possible thermal damage caused by iCure process • Sintering requires at least 2.0W of energy • Speeds kept constant • Failure modes: • Compression – Resin failure • Tension – Fibre pull out • Significant loss in mechanical stability at more intense exposures

16. Electroplating • Chosen as a method of improving electrical conductivity of DW tracks • Improvement to DW track conductivities (reaching ~50-70% bulk Cu) • Uses brush plating method to deposit copper • Several designs iterated: • Improvement to electrolyte flow • Higher current density • Lower surface damage to copper deposit • Be able to navigate around complex 3D structures • Automatic feed/extract system for fluid • Further improvements: • Use of local cathode ‘ring’ for local connection

17. Connector Tabs • Communications with the manufacturer • Requirements capturing • Resolving needs and expectations • Suitable for existing processes • Several designs created for manufacturer’s approval • Final design: Connector tab (c) • Soldered into place • Flexible

18. The DW Helmet • Aim: To replace chunky wiring in helmet shell with an integrated DW solution • DW elements successfully fabricated onto a section of the helmet shell • Hardware and DW elements were connected • DW elements passed preliminary round of aerospace durability tests

19. Conclusions • DW electronics demonstrated on an aerospace component • Developed a process that can fabricate DW electronics onto complex 3D structures • Future work: • Innovative full DW solutions to electronic applications • Repair work on damaged DW components • Scaling of process for full manufacturing environments

20. The End Questions?