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A dynamic analysis on the contaminant particles’ removal mechanism

A dynamic analysis on the contaminant particles’ removal mechanism in cryogenic carbon dioxide (CO 2 ) cleaning process. Dept. of Mechanical Engineering Chung- Ang University Nano -System Dynamics Lab. Seonghoon Lee, Pilkee Kim, Jongwon Seok. Motives & Objectives

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A dynamic analysis on the contaminant particles’ removal mechanism

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  1. A dynamic analysis on the contaminant particles’ removal mechanism in cryogenic carbon dioxide (CO2) cleaning process Dept. of Mechanical Engineering Chung-Ang University Nano-System Dynamics Lab. Seonghoon Lee, Pilkee Kim, JongwonSeok

  2. Motives & Objectives Cleaning methods for the removal of fine particles Theories of CO2 snow cleaning Modeling of particle detachment mechanism Simulation for particle detachment mechanism: Rebounding Discussion & Remaining issue Contents

  3. Motive - Weak point : Adhesion and removal mechanism among the particles - Requirement : Optimization of CO2 snow cleaning method by adopting reasonable adhesion model Motive &Objectives • Objectives - Adhesion mechanism between substrate & contaminant particle, CO2 snow particle & contaminant particle - Dynamic modeling and simulation - Optimization of CO2 snow cleaning method for high PRE (Particle Removal Efficiency)

  4. Cleaning methods for the removal of fine particles Cleaning methods Dry cleaning Wet cleaning • Chemical fluid application • - APM (Ammonia peroxide mix) • - HPM (Hydrochloric peroxide mix) • - SPM (Sulfuric peroxide mix) • - DHF (Diluted hydrofluoric acid) • Sputtering • Chemical dry-cleaning • UV/O3 cleaning • Laser Cleaning • Cryogenic Cleaning • Megasonic cleaning method

  5. Theories of CO2 snow cleaning ■ The principal mechanisms - Phase transition : gas & solid CO2 (2 phase) - Nucleation process - Particle removal mechanism • Phase transition 1 phase CO2 ( about 60 bar, -80℃) Container Adiabatic expansion process Gas CO2 + Solid CO2 (about 1bar, -80℃)

  6. Liquid CO2 Gas CO2 Solid CO2 Theories of CO2 snow cleaning • Nucleation process - For gas CO2source (Build-up process) - For liquid CO2source (Break-down process) • Dry ice snow yield 45 % for liquid source >> 8 % for gas CO2

  7. (50%) (40%) (10%) Theories of CO2 snow cleaning • Particle removal mechanism • Adhesion forces • Removal forces - Momentum transfer by solid CO2 - Drag force by gas CO2 - Thermophoresis - Van der waals force - Electric double layer force - Capillary force - Hydrogen bond • detachment : Rebounding, Rolling, Sliding, Lifting Adhesion force Removal force >

  8. Hertz model GT-JKR model JKR model Modeling of Particle Detachment Mechanism ■ Contact model • Hertz model : Model considering contact and deformation for external force • JKR model : adhesion force + Hertz model GT-JKR model : surface roughness + JKR model • Contact between CO2 snow & contaminant particle  Hertz model • Contact between substrate & contaminant particle  JKR model

  9. d1 : displacement of CO2 snow , d2 : displacement of contaminant y1, y2 d1 x1 x2 d2 Modeling of Particle Detachment Mechanism ■ Particle detachment Dynamic modeling of rebounding by vertical collision among particles v

  10. Modeling of Particle Detachment Mechanism • ■ Assumption • Perfect-elastic bodies without plastic deformation for each materials • Shape of particles : Spherical contaminant / Spherical dry-ice • Contact model : Hertz model, JKR model • Removal mechanism : Rebounding by vertical collision • No gravity effect ■ Material properties

  11. Contaminant displacement Dry-Ice displacement Simulation for particle detachment mechanism : Rebounding ■ Dynamic characteristics according to collision velocity • Contaminant radius : 0.1 ㎛ • Snowradius: 1 ㎛ Contaminant remain Contaminant remain (a) Initial Collision velocity : 3 ㎧ (b) Initial collision velocity: 5 ㎧ Contaminant removal Contaminant removal (c) Initial collision velocity: 8 ㎧ (d) Initial collision velocity: 10 ㎧ Collision velocity ↓ : Insufficient momentum

  12. Contaminant displacement Dry-Ice displacement Simulation for particle detachment mechanism : Rebounding ■ Dynamic characteristics according to contaminant radius • Snow radius : 1㎛ • Snowvelocity : 1㎧ Contaminant remain Contaminant remain (a) Contaminant radius : 0.1 ㎛ (b) Contaminant radius : 0.5 ㎛ Contaminant remain Contaminant removal (d) Contaminant radius : 2 ㎛ (c) Contaminant radius : 1㎛ Radius ↓ : Adhesion force increase, Radius ↑ : Insufficient momentum

  13. Conclusion & Remaining Issue • Conclusion Finally, we concluded that the results of this simulation are similar to general tendencies of fine particles in the cleaning process. • First simulation shows that the insufficient momentum of snow induces the particle contaminant to remain on the substrate. • Also it is found that the fine particle is difficult to remove from the substrate surface as known generally • Remaining Issue • Elasto-plastic material • Surface roughness • Sliding, rolling & lifting

  14. Thank you

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