Thick Film Silver Circuit Conductor Adhesion to Vitreous Substrates

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Alumina (Al2O3) is currently the industry standard substrate for thick film circuit conductors. Recently developed high speed/precision femto-second lasers can fabricate fine diameter thru-vias on fine pitches in glasses and fused silica. Thru-via interconnects with these miniaturized dimensions are not possible using alumina substrates. Miniaturized glass thru-via substrates needed for mobile communication products (next Gen cellphones) require high conductivity metallic circuit traces that are well bonded to the glasses. The conductors were assessed by comparison for resistivity shifts and tested for mechanical adhesion variation. Sputter coating of silver onto borosilicate slides through various intensities was done to determine adhesion capabilities as well as baseline resistivity measurements. Application of silver paste onto both borosilicate and quartz glass was attempted to determine adhesion and resistivity values. Various methods of attaining adhesion to the glasses was explored such as, painting of paste, sputter coating foundation, and a combination of the two. The sputter coating offered lower resistivity values and as good as adhesion while the silver paste displayed higher resistivity values due to less silver content in paste and thermal stress issues leading to cracking. The microelectronics industry is challenged with the development of copper (Cu) and silver (Ag) adhesion to vitreous glasses and fused silica. Thick film circuits are used in almost all electronic industry applications and would benefit from these discussed technical improvements.
Thesis completed in partial fulfillment of the requirements for the Alfred University Honors Program.
Honors thesis, Glass Engineering, Chemistry, Microelectronics