A Drop-on Printhead Suitable for Hot and Relatively Viscous Liquids

Transcription

1 Institut für Mechatronik Heilbronn A Drop-on on-demand Printhead Suitable for Hot and Relatively Viscous Liquids Wolfgang Wehl Jörg Wild Björn Lemmermeyer Michael KüblerK International Workshop on Ink-jet Printing of Functional Polymers and Materials June 2005, Eindhoven, The Netherlands

2 Institut für Mechatronik Heilbronn (University of Applied Sciences) Prof. W. Wehl B. Lemmermeyer Prof. J. Wild M. Kübler 2

3 Flip-Chip Really very Simple, or? die (solder) bumps contact pads substrate 0,5 mm [adapted from Reichl Direktmontage 3.40] 3

4 The Problem: Bump Production 1. Stencil Printing Advantages: reasonably priced Disadvantages: lack of miniaturization potential, stencil required prevents use for rapid prototyping 2. Galvanic Deposition Advantages: excellent miniaturization Disadvantages: prolonged and costly production, mask(s) required prevents use for rapid prototyping Up to now no production method for bumping exists which is reasonably priced, reliable and harmless to the environment! 4

5 Piezo-Jet The Functional Principle piezo actuator throttle pressure chamber nozzle 5 mm 5

6 Piezo-Electric Drop-on on-demand-printhead nozzle pressure chamber supply chamber glass covering piezo actuator silicon die 34 x 15 mm 2 6

7 Drop-on on-demand-printtheads: much more than only Ink Sprayers! varnishes oils glues melted waxes fuels mercury why not hot, liquid metals, too? [Video: TU München, Feingerätebau] 7

8 The Invention: The Metal-Jet Printhead micro machined die ceramic housing (ZrO 2 ) heater passivated tip for thermal decoupling piezo-electrical lamella actuator active part glass silicon nozzle 8

9 Function of the Metal-Jet Printhead 1. heater on 2. solder melts 3. electrical stimulation metal-jet printhead ejects droplets 9

10 Many Contradictory Challenges 1. Solder Leading System Tolerances in micro meter range Perfect thermal conductivity Homogenous temperature allocation 2. Actuator and Fixtures Very less thermal conductivity 3. Connections High force transfer (pull forces too) Partly tense for liquid and gaseous flows (solder / inert gas) 4. General Temperature Resistance up to 300 C (option 700 C) Same material coefficients of expansion 10

11 A Micro System Core of the Metal Jet Printhead 34 x 10 mm 2 Micro machined silicon die with Pyrex glass covering Advantages high thermal resistance chemical, mechanical resistant micro machine made 11

12 Structure of the Metal Jet Printhead Drive: Piezo lamella actuator with a zirconium oxide fixture Advantages high thermal resistance low thermal conductivity lot of design scope solder tank heater die fixture piezo ceramic 12

13 the Challenge is Putting it together! heating to operation temperature: ΔT > 250 K F F connection points F Pyrex/silicon ceramic (ZrO 2 ) piezo ceramic α Si = 2, K -1 α ZiO2 = K -1 α Piezo = 6, K -1 13

14 The Ingenious Simple Solution and Pyrex/silicon piezo ceramic 14

15 ... how it Works: In an Acoustic Manner Pyrex-glass solder micro system (Si) piezoelectric actuator A B heating droplet nozzle passive zone actuating zone 15

16 Propagation of Tensile and Pressure Waves a b c d B t 4 +F A U t 0 t 5 -F t 1 t 6 t 2 t 7 t 3 t t 8 16

17 The Assembled Metal Jet Printhead 17

18 Metal-Jet: Solder Droplet Ejection 18

19 Drop-on on-demand-printing of Different Liquids 1,0 potential of the IMH technology η/pa s 4 0,1 2 various oils glycerine 1. bubble-jet 2. piezo-jet (standard) 0,01 0, n-propanol Sn63Pb37 solder 3. hot-melt piezo-jet (Spectra) 4. hot-melt piezo-jet (IMH) water 0, t/ C 19

20 Micro dosing Additional Applications Ejection of difficult fluids at high temperatures, too Varnishes, oils, glues, fluxes, waxes and so on Rapid Prototyping Manufacturing of small, metallic, robust and thermal resistant devices 3D-MID (Moulded Interconnected Device) Metallization and passivation of three-dimensional devices 20

21 Summary The new printhead technology of the Institut für Mechatronik Heilbronn allows ejection of liquids up to temperatures of 300 C and viscosities of 400 mpa s A smart thermal decoupling of the piezo actuator prevents risk of destruction Acoustic operation protects the parts of the printhead from thermal stress Wafer bumping is a pilot application of the new printhead Other applications are micro dispensing of difficult liquids, rapid prototyping, 3D-MID metallization 21