Sample Preparation or Sample Prep

Always Handle samples with GLOVED HANDS!

Best Case Scenario Samples are solid conducting samples

When samples are not conductive they can be made conductive Au/Pd coating Carbon Coating does not have to be thick to be effective

MRC Au/Pd Coater Carbon Rod attachment for carbon coating

Sample Stubs There are several types of sample stubs available for mounting samples

Mounting samples to stubs Affix the sample to the stub using appropriate media Carbon or Silver Paint Double Stick Carbon Tape or dots Double Stick Copper Tape Super Glue* Double Stick Tape* *Not recommened for use in the S4700

Grounding Samples Although a sample might be coated it might not be grounded. Provide a good “path to ground” to reduce charging effects Silver Paint Carbon Paint Copper, Nickel, Silver, or Aluminum tape

Sample Types Metals Ceramics – Porous, Insulating Thin Films – Break immediately prior to mounting Geological – Mount and polish Glass – Insulating, Amorphous Polymers – Interaction with electron beam Nano samples Circuits – Insulating and conducting Wafers – Insulating Mounted Samples – Out gassing Particles or particulates

Metals Polished and etched – Grains Cleaned of excess oils Typically does not need assistance with grounding unless mounted in epoxy

Ceramics Insulating need coating and good path to ground Porous samples need to be in vacuum prior to SEM examination to reduce out gassing Polishing and etching to see grains

Thin Films Break prior to SEM examination to avoid contamination Thin Au/Pd coating Better if not on a glass substrate

Si Wafers and Glass Scribe across the back or at the edges Break prior to SEM examination Coating and good path to ground

Epoxy Mounted Samples Polished to a mirror finish Polishing scratches detract from desired images. Methodology is sample dependant Use Optical Microscope to view polishing progress Kept under vacuum to reduce amount of out gassing

Particles or Particulates Use appropriate mounting media Ensure the particles are attached firmly to the stub Blow off excess particles prior to coating Coat, if possible use a moving stage

Shielding In some cases the sample surface can be shielded with a metal foil can reduce charging effects. A piece of metal foil is placed on the sample allowing only a small amount of the surface to show

Sample Mount Put the sample stub on the “Sample Mount” the correct way. The bottom of the mount should be the widest part Adjust the height with the “preset height jig”

Lock washer Height screws Mount base Correct sample mount

Preset Height Jig

Sample Prep Summary All samples need to be handled with gloved hands – even in the processing lab! Proper sample prep cuts down on analysis time and insures better data collection Clean all stubs after use and store in appropriate place

GLOVES Storage and Work Bench