Method for accounting for clamp expansion in a coefficient of thermal expansion measurement

A method of increasing the accuracy in determining the coefficient of thermal expansion of a thin film sample material using a thermal mechanical analyzer, said thermal mechanical analyzer having a probe, sample holder, heater, thermocouple, differential transformer, core, force generator, analysis software and having two clamps to hold said thin film sample comprising a top clamp element and a bottom clamp element;

• said thin film sample material having a top and a bottom,
• initially securing said top and said bottom of said thin film sample material between said top and bottom clamps respectively, then measuring the length of said thin film sample material from said top clamp to said bottom clamp, fastening said top clamp to said probe, and fastening said bottom clamp to said sample holder;
• applying a tensile force to said top clamp so that said thin film sample material is under light tension,
• whereupon said thin film sample material is heated and cooled and a resulting relative displacement of said thin film sample material is measured, and the coefficient of thermal expansion test measurement result is determined according to the formula computing the difference of measured displacement D1, at temperature T1, and displacement D2, at temperature T2, divided by the difference between T1 and T2 according to CTE=(D1−D2)/(T1−T2),
• said clamps being fabricated from a material different from said thin film sample material that eliminates the influence of the thermal expansion or contraction of said clamp on said measurement of the coefficient of thermal expansion.