Finite Element Analysis and Design for Six Sigma

1. Finite Element Analysis and Design for Six Sigma Important Tools Used in Conjunction with HALT T. Kim Parnell, Ph.D.,P.E. PEC, www.parnell-eng.com OEI, www.ozeninc.com Mike Silverman, CRE Ops A La Carte,www.opsalacarte.com August 19, 2004

2. FEA & DFSS • FEA – Finite Element Analysis • DFSS – Design for Six Sigmaalso includes: • Design sensitivity • Materials (variations) • Geometry (tolerance) • DOE – Design of Experiments • Distribution of results rather than just a single result

3. How do you use FEA? • Finite Element Software • ANSYS • MSC.MARC, MSC.NASTRAN • ALGOR • ABAQUS • COSMOS • Understanding of Loads, BCs, Materials • Create the model & Run the analysis

4. FEA Model CreationSpeaker Normal Mode Analysis Dia : 17mm Thickness : 0.016mm Mat : aluminum E : 71e9 N/m^2 v : 0.3 p : 2700 kg/m^3 Element : Shell 63 : Mass 21

5. FEA & DFSS Application Example:MEMS Device - Linear Resonator

6. 0.2 mm 19 mm Quality of MEMS Devices: Linear Resonator • Package • Chip is inside package • Device is on chip

7. Quality of MEMS Devices: Linear Resonator Device markets & Applications • ABS • Seatbelt restraint/ tensioning • Active suspension • Rollover detection • Headlight leveling • Joysticks • Mouse • Earthquake detection • (gas shutoff) • Electro-Mechanical Filter

8. Quality of MEMS Devices: Linear Resonator Multi-Physics Problem: Electromagnetic & Structure Interaction Equilibrium between electro-magnetic forces and moving comb spring back • Random Input • 14 different manufacturing tolerances +/- 10% • Young’s Modulus +/- 10% • Poisson’s Ratio +/- 10% • Output • Maximum Deflection

9. Quality of MEMS Devices:Linear Resonator One Tooth Model only geometry parameters studied Moving Comb Finger Width Moving Comb Spine Width Moving Comb Finger Thickness • Only 3 out of 14 geometry parameters are important • Efficiently guide the design process to product improvement • Efficiently guide the quality control process

10. Quality of MEMS Devices:Linear Resonator Entire Resonator Model geometry and material studied • Very good agreement between Monte Carlo (400 FEA) and Response Surface Methods (49 FEA + 10’000 on Response Surface) • Scatter Range of “Maximum Displacement” has about a factor of 3 between lowest and largest value

11. Quality of MEMS Devices:Linear Resonator • Very good agreement between Monte Carlo (400) and Response Surface Methods (49) • Results enable a “Design for Reliability” (lower scrap rate, lower quality control cost, lower warranty costs)

12. Response Surface Methods (49) Monte Carlo (400) Quality of MEMS Devices:Linear Resonator • Very good agreement between Monte Carlo (400) and Response Surface Methods (49) • Same 3 geometry parameters and Young’s Modulus are important • More efficiently guide the design process to product improvement • Efficiently guide the quality control process • Efficiently guide and justify lab test spending

13. FEA & DFSS Application Example:Cell Phone Drop Test

14. Reliability of Electronic Devices: Dropping of a Cell Phone • Random Input • Drop Height • Inclination angle • Horizontal angle • Densities • … • Output • Maximum Stress

15. Most Probable Scenarios Reliability of Electronic Devices: Dropping of a Cell Phone Wide range of results (ratio ~ 60), single deterministic run will not cover the real scenario

16. Reliability of Electronic Devices: Dropping of a Cell Phone • More efficiently guide the design process to product improvement • Efficiently guide the quality control process • Efficiently guide and justify lab test spending

17. Summary • Finite Element Analysis (FEA) and Design for Six Sigma (DFSS) techniques are both useful tools in their own right. • They provide valuable insights and guidance when used in conjunction with a HALT program. • Use them at both the front end (pre-HALT) and the back end (post-HALT).