design of a testing machine for micro-devices follow up to clément gabry’s master thesis on...

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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

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Measurement devices

• displacement measurement

• load measurement

• optical table


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CSEM Machine

• PI linear stage

• 17 mm travel• ~ 1 um accuracy

• Load cell

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


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New Machine

• Linear measurement

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

• Load cell

• ~ 1-25 N range• 0.5 mN accuracy


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Displacement

• type of test : apply displacement, measure load.

• type of devices

• linear actuator

• linear stage


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Linear actuator


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

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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


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Linear Actuator• Solutions

• Hole

• “Meplas”

BUT

• Feasible?

• Loses precision?


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Linear Actuator• Solutions

• external device

• Feasible

• Compliance

• Small alignment error


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Piezo actuators

• very good precision

• good temperature ranges

• easy to mount and use

• price ranges affordable

BUT

• travel range NOT enough (10s of microns)


Price ~ 2-4’000 CHF

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Micro positioning stages

• some avoid the alignment problem

• very easy to mount

• stiffness

BUT

• load just not enough


Price ~ 15’000 CHF

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Piezo scanning stages

• Very good precision

• Possible to mount them on axis

BUT

• Travel range too small (38 um)


Price ~ 9’000 CHF

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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


Price ~ 10’000 CHF

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Nano positioning stage

• How to deal with the out of axis load?

• external device

• compliance

• adds weight to the load


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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


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Load Cells

• Type of load cell

• “donut type”

• avoids alignment problems

• Easy to fix

• stiffer than others


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Optical Tables

• Gives a high flexibility in positioning

• Not too expensive (so far)

• Probably better than rails


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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


design of a testing machine for micro-devices follow up to clément gabry’s master thesis on...

Documents

eo slide

cern phdt

chf slide

axis load influence

measure load

um load cell

um accuracy load cell

good precision easy