1. 1 Airflow based self-assembly of silicon chips on foils | 13 Air based self-assembly of silicon chips on foils Name:B. van Leeuwen Coach:Dr.Ir. M. Tichem Professor:Prof.dr. U. Staufer Specialisation:Production Technology Concern:Holst Centre Coach:Prof. Andreas Dietzel, PhD Date:08-07-2009

2. 2 Airflow based self-assembly of silicon chips on foils | 13 Contents Introduction Holst centre Micro assembly Problem description Simulation Dynamic simulation using COMSOL Dynamic simulation using Matlab Practical test Test setup Test results Applicability Results

3. 3 Airflow based self-assembly of silicon chips on foils | 13 Introduction Joint venture of TNO and IMEC-NL Research in future products System-in-foil: Low cost, flexible electronics which can be integration in disposable every day products Holst centre Source: Holst Centre

4. 4 Airflow based self-assembly of silicon chips on foils | 13 Introduction Problems appearing in micro assembly: Scaling effect  sticking effect Gripping and grasping difficult (delicate parts): Solution  Self-assembly Self-assembly: Processes in which a disordered system of pre-existing components forms an organized structure or pattern. (http://en.wikipedia.org/wiki/Self- assembly) Self-assembly can be based on different physical phenomena: For example: Mechanical, Fluidic or Gas based processes Micro assembly

5. 5 Airflow based self-assembly of silicon chips on foils | 13 Problem description Intelligent package, produced on roll-to-roll production Placement of flexible chips on flexible foil Chip placed on first foil, than laminated with second foil First foil makes placement possible Second foil takes care of electrodes and connections Context

6. 6 Airflow based self-assembly of silicon chips on foils | 13 Problem description Multi scale issue (large foil, small chips, accurate positioning) Ultra low cost, high volume production process Solution: Coarse placement followed by self-assembly Only air based assembly treated Context

7. 7 Airflow based self-assembly of silicon chips on foils | 13 Problem description Air flow based self-assembly Holes in foil will allow air through foil by backside overpressure. Velocity gradient above surface of foil. Chip will float and drift to final target location. Different designs possible Main problem Design a foil in a way that: the chip drift to the target location by airflow Context

8. 8 Airflow based self-assembly of silicon chips on foils | 13 Simulation 2D FEM simulation, solving the Navier-stokes equations using COMSOL. For different foil designs (velocity profiles) Obtaining static data 2D motion, solving the equations of motion using Matlab. Data form COMSOL stored in lookup tables Motion calculated using ODE solver Motion displayed Dynamic simulation using COMSOL and Matlab

9. 9 Airflow based self-assembly of silicon chips on foils | 13 Simulation The inlet velocity is imposed at the lower boundary and is defined by the friction of the nozzles: Dynamic simulation using COMSOL

10. 10 Airflow based self-assembly of silicon chips on foils | 13 Simulation Static simulation implemented for a certain chip position Dynamic simulation using COMSOL

11. 11 Airflow based self-assembly of silicon chips on foils | 13 Simulation Storing the obtained data lookup tables, dependent on x, y and φ Multiple lookup tables for: Forces and moments Different velocity profiles. Not all angle, y-position combinations possible because of geometry Dynamic simulation using Matlab

12. 12 Airflow based self-assembly of silicon chips on foils | 13 Simulation Dynamic simulation using Matlab The equations of motion can now be formulated

13. 13 Airflow based self-assembly of silicon chips on foils | 13 Simulation Dynamic simulation using Matlab Solving the equations of motion leads to the moving chip.

14. 14 Airflow based self-assembly of silicon chips on foils | 13 Practical test Features of test setup Overpressure in box by fan Foil attached on top Pressure measurement for feedback Events observed by camera Test setup

15. 15 Airflow based self-assembly of silicon chips on foils | 13 Practical test Test results

16. 16 Airflow based self-assembly of silicon chips on foils | 13 Applicability Practical applicability Integration possibilities Chip supply Chip alignment Chip fixation

17. 17 Airflow based self-assembly of silicon chips on foils | 13 Results Working simulation software Dynamic simulation using an array of static FEM calculations Practical proof of concept Design and build of test setup Successful testing of foil design Practical applicability Possible integration with other production steps Manny possibilities

18. 18 Airflow based self-assembly of silicon chips on foils | 13 End of slide show, click to exit.

19. 19 Airflow based self-assembly of silicon chips on foils | 13 Simulation (backup slide) Lookup tables for damping in y-direction: New forces calculated with initial speed New force subtracted from force without initial speed Force linearization round zero becomes damping force Dynamic simulation using COMSOL

20. 20 Airflow based self-assembly of silicon chips on foils | 13 Calculation (backup slide)