4 Application...............................................................................30 3 Handling concept and Simulation tool..................................22 2 Modelling of capillary forces..................................................11 1

Contents

Introduction...1

1 State of the art...2

1.1 Microsystems...2

1.2 Forces acting in the microworld...4

1.3 Handling principles for microassembly...5

1.4 Capillary gripper...9

2 Modelling of capillary forces...11

2.1 Fundamental parameters: Surface Tension, Contact Angle,

Laplace Equation...11

2.2 State of the art on the approximations of the capillary force...16

2.2.1 Energetic approach...16

2.2.2 Geometrical approach...17

2.2.3 Geometrical approach with normalization...19

2.2.4 Pendant drop...21

3 Handling concept and Simulation tool...22

3.1 Concept...22

3.2 Simulation tool...23

3.2.1 Problem definition: geometry and forces...23

3.2.2 The algorithms...24 3.2.3 Numerical simulation...25

3.3 Results...27

4 Application...30

4.1 Experimental layout...30

4.2 Deposition tests...34

5 Image analysis...37

5.1 Analysis with an image processing software...37

5.1.1 Elaboration of the images...37

5.1.2 Tilting error...38

5.1.3 Meniscus analysis...39

5.1.4 Centring effect...39

5.1.5 Releasing height...40

5.1.6 Analysis of the depositions...42

5.2 Other procedures for the analysis...43

5.2.1 Manual analysis...44

5.2.2 Model analysis...44

5.3 Experimental results...45

6 Conclusions and Future works...48

6.1 Conclusions...48

6.2 Improving capillary gripper...48

6.3 Thixotropic gripper

...49

Appendix A Meniscus Volume...52

Appendix B Simulation tool listing...55

Appendix C Control programs listings...60