BS IEC 62047-31:2019 pdf free.Semiconductor devices – Micro-electromechanical devices Part 31: Four-point bending test method for interfacial adhesion energy of layered MEMS materials.
5.2 Test machine
The test machine is a universal testing machine with a compressive loadcell, a servomotor, alinear guide,and a displacement sensor. Using a four-point bending fixture as shown inFigure 2, a pure bending moment is applied to a test piece with layered materials. Thediameter of the loading pins should be larger than the thickness of the test piece and fivetimes less than the length of the test piece.The load and the displacement shall be measuredusing a loadcell and displacement sensors installed on the universal testing machine duringthe test.The resolution of the loadcell shall be less than 1/100 of the critical load for interfacecracking,and the resolution of the displacement sensor shall be less than 1/100 of themaximum stroke during the test. The loading speed shall be chosen in a range from0,000 1 mm/s to 0,1 mm/s for steady state interfacial cracking without any inertial effect.Thebehaviour of crack extension shall be recorded at a speed larger than 10 Hz using a camerawith a microscope objective of 20x or more.
5.3 Test procedure
The test procedure is as follows:
a) Install a test piece on the four-point bending fixture of the test machine. The longitudinal direction of the test piece shall be aligned with the longitudinal direction of the fixture, andthe deviation angle shall be less than 1 °.
b) Apply a bending moment to the test piece to initiate a crack from the machined pre-crack or notch.This is for introduction of an interface crack at the weakest interface,and theapplication of bending moment shall be controlled by a displacement of the test machine.When the crack starts to extend,the actuator of the test machine shall be stopped toprevent the test piece from complete delamination. When the interface is brittle,and theadhesion energy is low,the test piece is susceptible to complete delamination afterinitiation of the crack at the machined pre-crack. When the initiated crack does not touchany material interface of the test piece,the displacement of the test machine shall beincreased to grow the crack further. The test machine shall be stopped and unloaded assoon as the interface crack is formed.
c)Apply a bending moment again to the test piece with the interface crack at a material interface, and record the load and the displacement during the test.The crack motion shallbe recorded to interpret the physical meaning of the measured critical energy release rate.d) Unload the test piece after a testing period.After testing, remove the test piece from the
test machine with caution for additional damage on the fractured surfaces of the test piece.lf possible,preserve the test piece for”investigation using electron and opticalmicroscopes.
e) Check the measured load-displacement curves according to Annex A. To obtain the interfacial adhesion energy,the interfacial cracking should proceed in a steady-statemanner and the load-displacement curve should be as in Figure A.1a). This test method isinvalid when the interfacial cracking is not in a steady-state.BS IEC 62047-31 pdf download.