Effect Of Al₂O₃,B₂O₃ And SiO₂ On The Physicochemical Properties Of Electronic Substrate Glass And Its Mechanism

The most basic part of the LCD is the electronic glass substrate,which is difficult to produce.Due to the strict technical blockade and product monopoly by American and Japanese companies,it has seriously affected the development of China's flat panel display industry.Foreign companies began research on electronic substrate glass decades ago,and they have led the industry.In contrast,China has only begun to increase its research intensity in a few years.At the same time,the huge domestic market requires us to create electronic substrate glass products with independent intellectual property rights,which requires a systematic theoretical foundation as a support.In the experiment,the electronic substrate glass SiO2-Al2O3-B2O3-RO(R=Mg,Ca,Sr)system was taken as the research object.The chemical stability,dielectric properties,thermal expansion properties,Vickers hardness and flexural strength of glass samples were studied in relation to Al2O3/SiO2,B2O3/SiO2 and Al2O3/B2O3.The structural impact testing methods such as MAS-NMR,FT-IR and XPS were used to investigate the changes in the performance mechanism and network structure.The relationship between the changes in the content of SiO2,B2O3 and Al2O3 single-factor components and the crystallization properties of aluminoborosilicate glass was also studied.This article draws the following conclusions:(1)The results of MAS-NMR spectrum showed that all of Al3+ existed in the[AlO4],and almost no signals from[AlO5]and[AlO6]were detected,which indicated that almost all Al3+ existed in the[AlO4]by combining with O2-.B3+has two coordination states of[BO4]and[BO3]respectively.The decrease in Al2O3 content is favorable for B3+ to form a four-coordinated structure.Through the IR test results,we can understand the types of functional groups and the connection state existing in the glass.In the FT-IR test results of the aluminum-borosilicate system glass,the peak of 793 cm-1 position is the Al-O bond stretching vibration in the aluminum-oxygen tetrahedron,and the absorption peak at the 685 cm-1 position is the B-O-B bond bending vibration in the boron-oxide triangle.The strongest peak at 1090 cm-1 is the stretching vibration of the bridge oxygen.The broadening on both sides of the peak belongs to Si-O-Al and B-O-Si.The peak of 1216 cm-1 originate from the vibration of B-O-Si.The absorption peak between 450?500 cm-1 is the rocking vibration of bridge oxygen in the glass network structure.(2)HF can react with glass,destroying the network skeleton.B2O3 and SiO2 content have a greater impact on acid resistance.When the content of B2O3 is large,the layered structure inside the glass is increased,and,it is easy to fall off in pieces after F-attack,thereby reducing the acid resistance.With the replacement of SiO2 with Al2O3 and B2O3 respectively,the alkali resistance of glass shows an increasing trend,but the degree of increase is different,because the increase in boron content causes the glass structure to depolymerize.When the SiO2 content does not change,the loss per unit area in the 5%NaOH solution fluctuates around 2 mg/cm2,indicating that the alkali resistance of the glass has a great relationship with the silicon atom content in the network skeleton.(3)The dielectric constant depends on the O2-content of different polarizabilities in the structure.The decrease in SiO2 in the glass composition reduces the overall polarizability and the dielectric constant.The dielectric constant has a negative correlation with the aluminum-boron ratio,from 5.80 to 4.95,and the dielectric loss is a minimum value of 1.2 at the position of Al2O3/B2O3=1.The increase of B2O3 content makes the glass structure loose,and the movement of alkaline earth metal ions increases,leading to an increase in conductivity loss and structural loss.The dielectric loss of the glass samples in this paper is between 1.3 and 1.9.(4)Coefficient of thermal expansion is the most intuitive manifestation of glass composition and structural changes.With the increase of B2O3/RO,the glass network structure is excessively disaggregated,the thermal expansion coefficient is continuously increased,and the glass transition temperature and strain point temperature are correspondingly reduced.Combined with the XPS test results,it was found that the decrease in SiO2 content has a greater effect on the amount of bridge oxygen.Determine the respective proportions of[BO3]and[BO4]in the boron-oxygen structure by NMR results.The thermal expansion coefficient of the glass sample in this paper is between 30×10-7?39×10-7?-1.AS2 has abnormal results due to slight crystallization,and the glass transition temperature varies between 680??770?.(5)Chemical bonding has a great influence on the hardness and flexural strength of glass.This paper finds that although the increase of B2O3 is not conducive to the tightness of the glass network structure,the increasing B-O bond energy(806 kJ)is much larger than the Si-O bond energy(445 kJ),which increases the flexural strength.As the most important network skeleton result,SiO2 has a greater impact on the hardness of the glass.With the continuous replacement of SiO2 by Al2O3,the hardness of the glass decreases from 657 kgf/mm2 to 624 kgf/mm2,showing a monotonically decreasing trend,but the flexural strength shows Monotonically increasing trend.(6)With the increase of the SiO2 content,the melting temperature of the glass increases,so that the entire crystallization temperature range moves to the high temperature region,and the upper limit reaches 1175?,which is not conducive to glass production operations.But it is beneficial to the stability of the glass structure.Increasing the content of Al2O3 is beneficial to the properties such as chemical resistance and mechanical properties of the glass,but at the same time,it will make melting difficult,increase the crystallization temperature and increase the crystallization tendency.The crystals precipitated on the glass samples were tested and observed,and it was determined that the type of crystals precipitated in the alkali-free aluminum borosilicate system glass was ?-SiO2.