Study On Electrical And Thermal Conductivity Of Gold Films Coated On The PI Substrate

With the development of flexible wearable electronic equipment towards miniaturization and high integration,nano-size metal film flexible conductive materials coated on the polymer substrate have been gradually applied in the field of flexible electronics.If the electrical and thermal conductivity of the nano-size metal film are poor,the increase in heat generation and decrease in heat dissipation capacity will been caused,which will greatly increase the energy consumption of the equipment,and it is not conducive to the stable operation of the equipment.Therefore,the research on the electrical and thermal conductivity of metal nano-films has gradually become the focus.However,physical properties of the substrate surface will been effected by type and heating of the substrate,thus affecting the electrical and thermal conductivity of the metal films.The gold films with an average thickness of 6.4 nm was coated on the PI substrate by magnetron sputtering.The effects of type,heating time and heating temperature of substrate on the in-plane electrical and thermal conductivity of the gold films were studied by transient electro-thermal technique(TET).On the basis of summarizing the experimental rules,the influence of electron grain boundary scattering in gold films on its electrical and thermal conductivity was quantitatively analyzed by using MS model.The main conclusions are as follows:(1)The in-plane direction Lorentz number,electrical and thermal conductivity of gold films coated on the PI film and PI fiber were measured by TET.The electrical and thermal conductivity of gold films are much lower than that of its bulk material.Compared with other flexible substrates,the gold films coated on the PI film substrate has the strongest electrical and thermal conductivity,and its the most suitable for application in flexible electronics.Due to the influence of electron grain boundary scattering,phonon heat conduction in the gold films coated on the PI fiber substrate is enhanced,resulting in its electric and heat conductivity no longer meeting the WF theorem,and Lorentz number is much larger than its bulk material's value.(2)When the heating time of PI film substrate is 1 h,the in-plane direction thermal and electrical conductivity of gold films tend to decrease with the heating temperature rising from 50 ? to 200 ?,and are both smaller than those of the gold films coated on the substrate without heating.As the proportion of phonon heat conduction to total heat conduction is relatively small,the influence of electron grain boundary scattering on the attenuation of the electricity and heat conduction of the gold film is similar,so the Lorentz number in the in-plane direction of the gold film always change little.(3)When the heating temperature is 200 ?,with the heating time increasing from 0 to 6 h,the in-plane thermal and electrical conductivity of the gold films both decrease first and then increase,and tend to be stable after 6 h.Before the heating time of 6 h,the change trend and amplitude of electrical and thermal conductivity of gold films are similar,resulting in the Lorentz number of gold films always changing little.However,with the heating time up to 6 h,the attenuation amplitude of the electrical conductivity of the gold films is larger than that of the thermal conductivity,resulting in the Lorentz number of the gold films being much larger than its bulk material's value.