Abstract:

Under the trend of integrated circuits developing toward precision and miniaturization， electronic glass with a low coefficient of thermal expansion （CTE） and a low dielectric constant has become a key basic material for applications such as semiconductor packaging and precision instrument substrates. This study employed Fourier transform infrared spectroscopy （FT-IR）， Raman spectroscopy， nuclear magnetic resonance （NMR） spectroscopy， differential scanning calorimetry （DSC）， thermal expansion analysis， and dielectric property measurements （10 MHz） to investigate the influences of the introduction amounts of B₂O₃ and Al₂O₃ on the network structure， thermal expansion properties， and dielectric properties of MgO-Al₂O₃-SiO₂ alkali-free low thermal expansion coefficient glass. The results show that when the m（B₂O₃）/m（Al₂O₃） （mass ratio） increases from 0.324 to 0.400， the degree of glass network polymerization increases， correspondingly， the CTE decreases from 3.68×10^-6 ℃^-1 to 3.59×10^-6 ℃^-1， the dielectric constant and dielectric loss decrease from 5.00 and 2.83×10^-3 to approximately 4.90 and 2.75×10^-3， respectively. When the m（B₂O₃）/m（Al₂O₃） rises to 0.485， the degree of glass network polymerization decreases； the CTE rebounds to 3.62×10^-6 ℃^-1， the dielectric constant and dielectric loss increase to 4.91 and 2.78×10^-3， respectively. When the m（B₂O₃）/m（Al₂O₃） further increases to 0.581， phase separation occurs during glass formation. Therefore， the appropriate introduction amount of B₂O₃ is 7% （mass fraction， the same below）， with an Al₂O₃ content of 17.5% and a m（B₂O₃）/m（Al₂O₃） of 0.400. At this point， the glass exhibits the lowest coefficient of thermal expansion （3.59×10^-6 ℃^-1）， with a dielectric constant of 4.90 and a dielectric loss of 2.75×10^-3.

Key words: B₂O₃, Al₂O₃, coefficient of thermal expansion, NMR, low dielectric constant, alkali-free glass