1

DESIGN OF A TESTING MACHINE FOR MICRO-DEVICES

Follow up to Clément Gabry’s master thesis on Structural Resistance of Silicon

Membranes

12/10/2014 CERN PH-DT-EO

2

Measurement devices

• displacement measurement

• load measurement

• optical table

12/10/2014 CERN PH-DT-EO

3

12/10/2014 CERN PH-DT-EO

4

CSEM Machine

• PI linear stage

• 17 mm travel• ~ 1 um accuracy

• Load cell

• 2N range, 0.1mN accuracy• 20N range, 1mN accuracy

12/10/2014 CERN PH-DT-EO

5

New Machine

• Linear measurement

• travel range : > 1 mm• resolution/incremental motion: 0.1 um

• Load cell

• ~ 1-25 N range• 0.5 mN accuracy

12/10/2014 CERN PH-DT-EO

6

Displacement

• type of test : apply displacement, measure load.

• type of devices

• linear actuator

• linear stage

12/10/2014 CERN PH-DT-EO

7

Linear actuator

12/10/2014 CERN PH-DT-EO

Advantages

• Simple geometry

• Allows an on-axis motion at all times

• Have good enough specifics

• Easy to mount

• Easy to replace

• Reasonable prices

Price ~ 3’000 CHF

8

Linear Actuator• Drawbacks

• More compliance in fixing method

• Compliance in mounting device

• Alignment problem (angular)

• Smaller travel ranges

• 50 N might introduce bending forces

• None linear encoder : backlash

12/10/2014 CERN PH-DT-EO

9

Linear Actuator• Solutions

• Hole

• “Meplas”

BUT

• Feasible?

• Loses precision?

12/10/2014 CERN PH-DT-EO

10

Linear Actuator• Solutions

• external device

• Feasible

• Compliance

• Small alignment error

12/10/2014 CERN PH-DT-EO

11

Piezo actuators

• very good precision

• good temperature ranges

• easy to mount and use

• price ranges affordable

BUT

• travel range NOT enough (10s of microns)

12/10/2014 CERN PH-DT-EO

Price ~ 2-4’000 CHF

12

Micro positioning stages

• some avoid the alignment problem

• very easy to mount

• stiffness

BUT

• load just not enough

12/10/2014 CERN PH-DT-EO

Price ~ 15’000 CHF

13

Piezo scanning stages

• Very good precision

• Possible to mount them on axis

BUT

• Travel range too small (38 um)

12/10/2014 CERN PH-DT-EO

Price ~ 9’000 CHF

14

Nano positioning stages

• Very good precision

• Easy to mount, or re-use

• Stiffness and “high loads”

• Long travel ranges

BUT

• Out-of-axis loading problem

12/10/2014 CERN PH-DT-EO

Price ~ 10’000 CHF

15

Nano positioning stage

• How to deal with the out of axis load?

• external device

• compliance

• adds weight to the load

12/10/2014 CERN PH-DT-EO

16

Load Cells

• Positioning of the load cell

• on the actuator side non alignment problem again

• on the support :

• easy to fix• easy to align• easily changeable

12/10/2014 CERN PH-DT-EO

17

Load Cells

• Type of load cell

• “donut type”

• avoids alignment problems

• Easy to fix

• stiffer than others

12/10/2014 CERN PH-DT-EO

18

Optical Tables

• Gives a high flexibility in positioning

• Not too expensive (so far)

• Probably better than rails

12/10/2014 CERN PH-DT-EO

19

Next step

• Modeling and analysis of errors

• influence of the notch-load non alignment

• influence of the out of axis load

• influence of the importance of symmetry

• influence of temperature on (optical) table and devices

12/10/2014 CERN PH-DT-EO