CN111718120A - Li-Al-Si photosensitive glass and preparation method thereof - Google Patents

Abstract

The invention provides a preparation method of Li-Al-Si photosensitive glass, which is prepared by using the following raw materials in parts by weight: 75-80 parts of SiO ₂ ; 8-12 parts of Li ₂ O; and 2-5 parts of Al ₂ O ₃ ; 1-4 parts of Na ₂ O; 3-6 parts of K ₂ O; 1-2 parts of ZnO; 0.05-0.2 parts of Sb ₂ O ₃ ; _0-2 parts of alkaline earth metals; 0.02-0.15 parts of CeO ₂ ; 0.15 servings. The invention effectively improves the dielectric properties and mechanical properties of the photosensitive glass by improving the ratio of raw materials and at the same time improving the production process. Applications in high frequency environments. In addition, due to the improvement of mechanical properties, it can adapt to the development trend of miniaturization of integrated circuit packages. At the same time, it is beneficial to improve the situation that domestic adapter board materials rely on foreign manufacturers, reduce the cost of domestic three-dimensional integrated packaging, and better promote the development of domestic integrated circuits.

Description

Li-Al-Si photosensitive glass and preparation method thereof

technical field

The present invention relates to the field of three-dimensional integrated packaging adapter plates, in particular to a Li-Al-Si photosensitive glass and a preparation method thereof.

Background technique

With the development of microelectronics technology, quantum effects such as tunnel penetration in integrated circuits have become increasingly prominent, and Moore's Law has also encountered unprecedented bottlenecks, and these bottlenecks are expected to be broken through advanced three-dimensional integrated packaging technology. Among them, the adapter board plays an important role in the three-dimensional integrated packaging technology: the chips are vertically interconnected through the high-density copper-plated through-hole adapter board, which greatly shortens the length of the interconnection line, which significantly reduces the system parasitic parameters, power consumption, signal delay and size, etc. Among many transition boards, Li-Al-Si photosensitive glass is considered to be the most potential 3D transition board due to its unique photolithographic properties, low loss, high density through holes, low cost, strong insulation and other properties. Material.

At present, there are two widely used commercial photosensitive glasses in the industry: (1) Foturan (Schott, Germany) based on Li-Al-Si glass system. (2) Photo-thermo-refractive glass (PTR) based on Na-Zn-Al-Si glass system. SCHOTT's Foturan photosensitive glass is widely used in electronics, biology and many other fields due to its high precision in microstructure patterning and stable and reliable quality. Its electrical and mechanical properties are as follows:

With the advent of the 5G era, the operating frequency of the chip will increase to the GHz frequency band or even millimeter wave, which puts forward higher requirements on the dielectric properties of the adapter board; the market's demand for multi-function and miniaturization of electronic products forces chip packaging The further reduction in size also requires smaller and thinner adapter boards, which poses challenges to the mechanical properties of the adapter boards. SCHOTT's existing Li-Al-Si photosensitive glass contains a large amount of alkali metal ions, so its dielectric loss at high frequency is still not optimistic, which limits the performance of Li-Al-Si photosensitive glass in high frequency environment. application. On the other hand, with the development of the miniaturization of the integrated circuit package, the thickness of the adapter plate is also continuously reduced, which also puts forward higher requirements on the mechanical properties of the glass. The most critical point is that the domestic adapter board materials cannot always rely on the photosensitive glass of the German company SCHOTT, otherwise it will not only increase the cost of domestic 3D integrated packaging, but also not master the key technologies by ourselves. into a passive situation. Therefore, it is necessary to independently develop high-performance and low-cost photosensitive glass, and master the subsequent patterning, metallization, anodic bonding and other processes, which will lay a solid foundation for my country's three-dimensional integrated packaging.

To this end, the applicant submitted an application number of 201710144943.5 on January 13, 2017, entitled "Sensitized Photosensitive Glass with Low Dielectric Loss and Production Method". By improving the formula and preparation process of the photosensitive glass, a dielectric For photosensitive glass with lower loss, with the deepening of research, the formulation and preparation process of photosensitive glass can be further improved on this basis, and photosensitive glass with better performance can be obtained.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a Li-Al-Si photosensitive glass and a preparation method thereof, so as to further improve the dielectric properties and mechanical properties of the photosensitive glass.

The technical solution adopted by the present invention to solve the technical problem is: the preparation method of Li-Al-Si photosensitive glass adopts the following raw materials in parts by weight to prepare:

Further, the alkaline earth metal includes one or more of MgO, CaO, BaO and SrO.

Further, the alkaline earth metals include MgO and CaO.

Further, the alkaline earth metal includes 0.5 parts of CaO and 0.5 parts of MgO.

Further, the following steps are included:

The raw materials are uniformly mixed and heated, so that the raw materials are heated to 800-900°C within 150-180 minutes to produce gas and opaque sintered products;

Continue to heat the raw materials, so that the raw materials are heated to 1200-1250 ° C within 70-100 minutes, and the sintered material begins to melt and gradually becomes transparent;

Continue to heat the raw materials, so that the raw materials are heated to 1400-1500 ° C in 30min-70min, the viscosity of the glass liquid is reduced, and gaseous impurities are released at the same time, so that the glass liquid is clarified;

The glass liquid is kept at a temperature of 1400-1500 ℃ for 100-200 minutes, so that the components are evenly distributed;

Cool the glass liquid by 150-250°C within 30-70 minutes, and then quench the glass liquid to 200-300°C within 20-50 minutes to obtain glass;

annealing.

Further, the annealing process is:

The initial temperature of the annealing furnace is 470-500°C, then the temperature is lowered to 180-220°C at a rate of 0.11°C/min-0.143°C/min, and finally cooled to room temperature within 500-800min.

The Li-Al-Si photosensitive glass is prepared by the above-mentioned preparation method of the Li-Al-Si photosensitive glass.

Further, the molar amounts of Si ⁴⁺ , Al ³⁺ and O ^2- in the glass satisfy: 1:2<(Si+Al):O<1:2.5.

The beneficial effects of the present invention are: the present invention effectively improves the dielectric properties and mechanical properties of the photosensitive glass by improving the ratio of raw materials and simultaneously improving the production process. In comparison, both the dielectric properties and mechanical properties are improved.

Description of drawings

Figure 1 is a diagram of a quartz glass network structure.

Fig. 2 is the network structure diagram of Li-Al-Si photosensitive glass.

Figure 3 is a graph of glass samples prepared at different cooling rates.

Figure 4 is a graph showing the relationship between the nucleation growth rate and the crystal growth rate and temperature.

Figure 5 is a TG-DSC graph of a glass sample.

Figure 6 is a schematic diagram of the UV absorption spectrum.

Figure 7 is a view of exposed and unexposed sample glass.

Figure 8 is an XRD diffractogram of an unexposed sample.

Figure 9 is the XRD diffractogram of the sample after exposure.

FIG. 10 is a schematic diagram of the Raman spectrum of each sample.

FIG. 11 is a graph of Gaussian fitting to the frequency band of 850 to 1250 cm ⁻¹ in the Raman spectrum.

FIG. 12 is a schematic diagram of the area ratio of the fitting peaks of the Gaussian fitting curve.

Figure 13 is a graph showing the relationship between the dielectric constant and frequency of the Sr-doped series samples.

Figure 14 shows the dielectric loss values of the Sr-doped series samples when the frequency is around 1 GHz.

Figure 15 shows the flexural strength and surface hardness curves of Sr-doped series samples.

Figure 16 is a graph of glass melting curves.

Figure 17 is an annealing graph.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The preparation method of the Li-Al-Si photosensitive glass of the present invention is prepared by using the following raw materials in parts by weight:

The quartz glass network structure is mostly connected by Si-O-Si bridge oxygen bonds with strong bonds, so it has the advantages of excellent dielectric properties and stability, small thermal expansion coefficient, etc., and is regarded as an ideal glass structure. , the structure diagram is shown in Figure 1. However, quartz glass has no photosensitivity and has a high melting point (1713°C), which will greatly increase energy consumption. If it is used as an adapter plate material, it must rely on laser through holes, which will also greatly increase the cost of the adapter plate.

Li-Al-Si photosensitive glass just makes up for this defect. In order to obtain good performance, the photosensitive glass is still dominated by SiO ₂ content, and its mass fraction accounts for more than 75% of the total content. However, after the addition of alkali metal oxides containing Li, Na and K, Li ⁺ mainly plays a "accumulation" effect on the glass network due to the large cation field strength, while Na ⁺ and K ⁺ mainly play a "fracture" effect, bridge oxygen The bond is broken to form a non-bridging oxygen bond, as shown in Figure 2 (R in the figure represents an alkaline earth metal), which destroys the original integrity and symmetry of the silicon-oxygen tetrahedron [SiO ₄ ], resulting in loose glass structure and poor performance. . And the greater the alkali metal content, the worse the performance becomes, so the content of alkali metal must be controlled. There are two main reasons for adding alkali metal: (1) Alkali metal has the effect of high temperature melting, so that SiO ₂ can be melted at 1400℃-1500℃ to reduce energy consumption and equipment performance requirements. (2) Li ⁺ is an important component of the precipitated lithium metasilicate Li ₂ SiO ₃ crystal phase, and then Na ⁺ and K ⁺ are added to form a "mixed alkali effect" to reduce the diffusion coefficient of alkali metals, thereby reducing the dielectric loss and thermal expansion of the glass. coefficients, etc. Alumina Al ₂ O ₃ is an intermediate oxide, which captures the surrounding free oxygen and enters the glass network in the form of tetrahedral [A1O ₄ ] ^5- , which can improve the viscosity, stability and mechanical strength of the glass melt, but too much. Alumina Al ₂ O ₃ will affect the electrical properties of the glass, and the content of Al ₂ O ₃ introduced into most glasses is 1% to 3.5%. [A1O ₄ ] ^5- has one more negative charge than [SiO ₄ ] ^4- and neutralizes the extra-network bulk ions such as alkali metals or alkaline earth metals to reduce the charge stress. The addition of alkaline earth metals is on the one hand to further prevent the migration of Li ⁺ , Na ⁺ , K ⁺ alkali metal ions with the external electric field; Ion is an inert gas ion, so it has low polarizability and a large coordination number in the glass network. It is a good glass network modifier. Therefore, doping an appropriate amount of alkaline earth metal can improve the mechanical properties and dielectric properties of glass. Appropriate zinc oxide can improve the alkali resistance of the glass and can also protect Ag+ from being reduced to silver atom Ag at high temperature. Too much zinc oxide will enhance the crystallization tendency of the glass. Sb ₂ O ₃ is both a reducing agent, and the relevant reduction reaction formula is

2Ce ⁴⁺ +Sb ³⁺ →2Ce ³⁺ +Sb ⁵⁺

At the same time Sb ₂ O ₃ is a clarifying agent. Ce ₃₊ absorbs photon energy and releases free electrons required for crystallization, and acts as a photosensitizer. The nucleating agent Ag+ captures the above free electrons to form atomic clusters, which gradually grow into crystal nuclei with the increase of temperature, thereby inducing the precipitation of lithium metasilicate crystal phase (Li ₂ SiO ₃ ).

Among the alkaline earth metals, radium, beryllium, etc. are radioactive or highly toxic. Therefore, the alkaline earth metals of the present invention include one or more of MgO, CaO, BaO and SrO.

Reasonable glass sintering temperature curve and annealing temperature curve are the premise of preparing Li-Al-Si photosensitive glass with stable structure and performance. Insufficient will cause obvious small bubbles, as shown in 1# in Figure 3; the high sintering temperature is increased, and sometimes unknown yellow filaments appear when the holding time is long, as shown in Figure 3 in 2#; After continuous exploration, Finally, a transparent glass without obvious bubbles and any unknown yellow filaments as shown in 3# in Figure 3 is obtained. The improved glass forming process includes the following five stages:

Stage 1: The raw materials are uniformly mixed and heated, so that the raw materials are heated to 800-900° C. within 150-180 minutes, and gas and opaque sintered products are produced. Before 800～900℃, the raw materials mainly participate in the reaction in the form of solid state, and the products include gases such as CO ₂ and opaque sintered products composed of silicate and SiO ₂ .

Stage 2: Continue to heat the raw material, so that the raw material is heated to 1200-1250° C. within 70-100 minutes, and the sintered product begins to melt and gradually becomes transparent. As the temperature rises to 1200-1250 °C, the sintered material begins to melt and slowly becomes a transparent body, but there are a lot of bubbles, streaks and uneven composition in the glass liquid.

Stage 3: Continue to heat the raw materials, so that the raw materials are heated to 1400-1500 ° C in 30-70 minutes, the viscosity of the glass liquid is reduced to about 10Pa·s, and gaseous impurities are released at the same time to clarify the glass liquid.

Stage 4: The glass liquid is kept at a temperature of 1400-1500 ℃ for 100-200 minutes. Due to the effect of diffusion, the chemical components gradually tend to be evenly distributed. At this time, the streaks and bubbles have gradually decreased.

Stage 5: Cool the glass liquid by 150-250°C within 30-70 minutes so that the glass liquid has a suitable viscosity when discharging, and then quench the glass liquid to 200-300°C within 20-50 minutes to obtain glass. Since glassy substances have higher internal energy than crystalline substances, according to the principle of minimum energy, glass always has a tendency to reduce the self-generated internal energy and transform into polycrystals. The reason why glass can exist stably is that the difference between it and the internal energy of the crystal cannot be greater than the crystallization barrier, otherwise the glass will crystallize. The core idea of kinetics is that the cooling rate of the glass melt is the key to glass formation. The fact that supports this view is based on the fact that the best glass formers (such as SiO ₂ , B ₂ O ₃ , etc.) will slowly cool the melt, and crystals will precipitate; even metals that are not suitable for vitrification, as long as the cooling rate of the melt is made. The speed at which the particles are arranged to form crystals is greater than that of the metallic glass. In the process of quenching from melt to glass body, nucleation and crystal growth are two processes of material crystallization. Figure 4 is a graph showing the relationship between the rate of nucleation and crystal growth and temperature. The temperature decreases from d to b In the process of , the crystal growth rate first increases and then decreases to 0. In the process of decreasing the temperature from c to a, the nucleation rate first increases and then decreases to 0. The crystallization condition is that the crystal grows on the basis of the nuclei, that is, crystallization occurs. In the temperature range between b and c, to prevent or reduce crystallization, the time for the glass to decrease from temperature c to temperature b can be reduced, that is, the cooling rate can be accelerated. Therefore, in the present invention, the glass liquid is quenched to 200-300° C. within 20-50 minutes, so as to reduce the crystallization phenomenon and ensure the glass quality.

In the process of discharging and cooling, due to the influence of cooling environment, pouring method and other conditions, stress will inevitably occur in the glass matrix. The existence of this stress will greatly reduce the mechanical strength of the glass and even cause the glass to crack. To eliminate this stress and improve the uniformity of the chemical composition of the glass, the glass needs to be kept at a certain temperature for a long enough time and then slowly cooled down so that there is no more stress beyond the allowable range. We call this process the annealing heat treatment of glass. The properties of glass samples prepared from different melting temperature curves are also different, especially the heat treatment annealing curve after the glass body is poured and formed will directly affect its mechanical properties, so it is necessary to explore a more reasonable set of annealing process parameters Curve, the specific annealing process of the present invention is:

The initial temperature of the annealing furnace is 470-500°C, then the temperature is lowered to 180-220°C at a rate of 0.11°C/min-0.143°C/min, and finally cooled to room temperature within 500-800min.

The annealing upper limit temperature of the glass can be set above the transition temperature T _g and below the softening temperature T _s . On the one hand, in this temperature range, the diffusion barrier in the glass matrix is lowered, and the particles can absorb heat for displacement, thereby weakening the thermal stress caused by the temperature gradient in the glass body and the structural stress caused by the inhomogeneity of the composition. On the other hand, the softening temperature T _s is usually lower than the crystallization temperature T _c so that the glass body does not spontaneously crystallize, and the shape of the cast glass is not changed.

Figure 5 is the TG-DSC curve diagram of the glass sample. It can be seen from Figure 5 that the transition temperature T _g of the glass sample is around 470 °C, the melting point temperature T _m is around 932 °C, and there is no downward peak in the whole heating process. The exothermic peak indicates that the unexposed sample will not spontaneously crystallize only due to heating, and the crystallization performance is stable. At the same time, the TG curve was observed, and the weight of the glass remained almost unchanged during the heating process, indicating that the glass sample did not contain components that were easily volatile or decomposed by heating, further indicating that the thermal stability of the glass was good.

The annealing of glass is essentially reflected in the following two processes: first, stress reduction and even disappearance; second, to prevent the generation of new stress. During the cooling process after the heat preservation, the stress in the glass body is mainly related to the temperature gradient, and the stress generated by different cooling rates, product thicknesses and properties varies. According to the above analysis and sample DSC test results, the maximum annealing temperature is set to 500°C, and the cooling rate needs to be determined according to the thickness and shape of the experimental sample.

In order to reduce the mobility of Li ⁺ , Na ⁺ and K ⁺ under the action of an external electric field and to densify the glass network structure, some metal oxides with low self-polarizability, strong cation field and moderate radius need to be doped. Based on the above features, the present invention adopts alkaline earth metal series with more coordination numbers for doping. Compared with alkali metal ions (except Li ⁺ ), alkaline earth metal ions have larger field strength, stronger binding ability with oxygen ions, and their radius is slightly larger than that of alkali metal ions, which makes their mobility slower under the action of external electric field and can effectively Block the migration of alkali metal ions. However, alkaline earth metal ions also belong to the out-of-network ions. Too much content will also lead to a sharp increase in the content of non-bridging oxygen, which will destroy the stability of the glass network structure. Therefore, it is necessary to explore the optimal doping content of each alkaline earth metal ion to obtain better Under the condition that other raw materials and production process remain unchanged, the types and contents of alkaline earth metals are changed, and multiple glass samples are prepared to verify the influence of types and contents of alkaline earth metals on glass properties.

The experimental sample of undoped alkaline earth metal (0wt%) is named S ₀ , and the content of doped SrO is used as the subscript of the nomenclature, for example, C _0.5 , C ₁ , C _1.5 , and C ₂ represent 0.5 wt % and 1 wt %, respectively , 1.5wt%, 2wt% SrO doped samples.

(1) Photosensitive performance verification

The photosensitivity is the basic premise of the Li-Al-Si photosensitive glass in this experiment. Whether it has photosensitivity determines whether the subsequent exposure, etching and other micro-patterning processes can be realized. In order to verify the photosensitivity of the glass sample in this experiment, the exposure wavelength was first determined according to the test of the UV absorption spectrum of the glass sample, as shown in Figure 6: there is an obvious absorption peak at the wavelength of about 310nm, which corresponds to the Ce ₃₊ The reaction process of absorbing photon energy and releasing electrons, the reaction equation is shown in the formula. Then, the polished sheet-like photosensitive glass sample was placed under the ultraviolet light of a mercury lamp with a wavelength of about 310nm for 15min mask exposure. After exposure, the surface of the glass sample needs to be cleaned and placed in an annealing furnace for annealing and development.

In order to generate lithium metasilicate (Li ₂ SiO ₃ ) crystalline phase from the exposed glass samples, the following annealing process is used: the exposed and unexposed glass samples are placed in a high-temperature annealing furnace at a rate of 3 °C/min with the furnace. After rising to 555°C, the temperature was kept for two hours, and then slowly lowered to room temperature at a cooling rate of 1°C/min. It is evident from Figure 7 that the UV-exposed and annealed samples turned into reddish-brown glass-ceramics, while the samples that were not UV-exposed but subjected to the same annealing procedure still appeared to be clear-colored glassy. In order to determine the phase of the reddish-brown crystals and whether there is a microcrystalline phase in the unexposed glass body, X-ray diffraction (XRD) analysis was performed on the two samples. The test results showed: as shown in Figure 8, the unexposed glass There is no sharp crystallization peak on the test curve of the sample, indicating that the sample is still in a glass state, that is, no crystal phase is formed. However, as shown in Figure 9, there are obvious crystallization peaks on the XRD curve of the exposed glass sample. According to the comparison standard card PDF#72-1140 and PDF#40-0376, it can be determined that the crystals formed in the exposed glass are mostly divided It is lithium metasilicate Li ₂ SiO ₃ , and only a small part of the crystal is Li ₂ Si ₃ O ₅ in the lithium disilicate crystal phase.

The above results indicate that the doping of alkaline earth metal Sr ²⁺ does not affect the photosensitivity of Li-Al-Si photosensitive glass, and may even promote the performance of selective crystallization. For example, the peak intensity of C _1.5 around 38° is greater than that of S ₀ sample the peak intensity.

(2) Structural performance analysis

Under the condition of constant external conditions, to improve the performance of glass samples must consolidate their microscopic network structure. In order to explore the influence of alkaline earth metal Sr ₂₊ on its structure after entering the glass grid, the Raman spectrum of this series of samples can be used for structural analysis. The Raman spectrum is shown in Figure 10 below, and the vibration mode corresponding to the Raman spectrum is as follows :

From the Raman spectrum and vibrational mode table, it can be seen that except for the C _0.5 sample, the displacement and intensity of the Raman vibration peaks of the other three doped samples and the undoped sample S ₀ have little change, which can at least explain a small amount of SrO Doping does not cause significant damage to the glass network structure. However, the Si-O0 bending vibration peak of the bridge oxygen bond Si-O0 of the C _0.5 sample at 471 cm ^-1 is higher than that of the sample S ₀ , and the vibration peaks at 555 cm ^-1 and 1080 cm ^-1 are significantly lower. This microstructure may cause the Changes in sample properties.

According to the above analysis, ^{SrO doping} within 2%wt has little effect on the vibration of the glass network and will not cause more vibration loss. 1, 2, 3, 4, n is the number of bridge oxygen) content distribution. In order to further understand how Sr ²⁺ affects the glass microstructure, we need to perform Gaussian fitting to the band between 850 and 1250 cm ^-1 in the Raman spectrum. In the above frequency bands, about 950cm ^-1 , 1000cm ^-1 , 1090cm ^-1 , 1150cm ^-1 correspond to Q ¹ (Si ₂ O ₇ ^6- dimmer), Q ² (SiO ₃ ^2- chain), Q ³ (Si ₂ The Si-O stretching vibration of O ₅ ^2- sheet), Q ⁴ (SiO ₂ 3Dnetwork) structural unit, the fitting curve is shown in Figure 11.

The ratio of the four peak areas after fitting corresponds to the relative content of the corresponding Q ¹ , Q ² , Q ³ , Q ⁴ structural units in the glass structure. After fitting and calculation, the four peaks are given in the form of percentages The ratio of the areas of the fitted peaks is shown in Figure 12. It can be clearly seen from the three-dimensional sector diagram that from S ₀ to C ₁ samples, the relative content of Q ⁴ structural unit decreased from 36.16% to 18.34%, while the Q ³ structural unit increased from 31.59% to 54.94%, Q ₁ The relative content of structural units remained basically unchanged, but the content of Q ² structural units had a decreasing trend. When the doping content of SrO exceeds 1%, the trend begins to reverse: the relative content of Q ² and Q ⁴ structural units increases slightly, while the content of Q ³ structural unit decreases. These two distinct phenomena can be explained by the following two reaction equations:

formula one

2Q ⁴ +Q ^2- → 2Q ³

Formula 2

In the formula, O ^2- comes from the free oxygen provided by SrO. When the doping content of SrO is less than 1 wt%, the reaction formulas together play a major role: the ^Q4 structural unit absorbs the free oxygen provided from SrO to become the ^Q3 structural unit. A small part of the Q ² structural unit is also converted into Q ³ through the reaction formula 2; once the doping content of SrO exceeds 1wt%, the content of the Q ³ structural unit is too high, which will be partially converted into Q ⁴ structural unit and Q ² Structural units. If the doping content of alkaline earth metals is too high, in addition to the reaction process of formula 1, the following reaction processes will mainly occur

formula three

2Q ³ +Q ^2- → 2Q ²

formula four

2Q ² +Q ^2- → 2Q ¹

The increase of Q ² and Q ¹ structural units will seriously destroy the symmetry and stability of the silicon-oxygen tetrahedron [SiO ₄ ], which is why excessive alkaline earth metal doping will lead to the deterioration of glass properties.

After understanding the effect of alkaline earth metal oxide SrO on the glass structure, let's take a look at the performance test results of this series of samples, as shown in Figure 13, Figure 14 and Figure 15. The five-pointed star in the figure indicates that the comprehensive performance of this series of samples is the best. The best sample (the same below). Comparing the experimental results of the dielectric and mechanical properties here with the previous structural analysis, the following rules can be found: Except for the C _0.5 sample, the values of dielectric loss and dielectric constant increase with the increase ^of the Q structural unit. decreased and increased with the decrease of the ^Q3 structural unit; the values of flexural strength and surface hardness were just opposite to the dielectric properties: the mechanical properties first increased with the increase of the ^Q3 structural unit, and then with the decrease of the ^Q3 structural unit and become weaker. Among them, C ₁ has the highest content of Q ³ structural unit, so the comprehensive performance is the strongest. As predicted by Raman spectroscopy, the dielectric constant, dielectric loss, and flexural strength of the C _0.5 sample all deviate from the changing trend of this system. After analysis and investigation, the reason for the abnormality of the C _0.5 sample is likely to be caused by a large degree of inhomogeneity in the matrix of the sample, because the sample was reconstituted and ground to be uniform, and the sample was tested by the same sintering and annealing process. The results are greatly improved, for example, the mechanical strength is changed from the original 78.5MPa to 155MPa, so that the mechanical properties of the C group samples from S ₀ to C ₁ to C ₂ basically follow the trend of increasing first and then decreasing (explained here, not shown in the figure).

(3) Analysis of the cause of the result

The reasons for the improved dielectric and mechanical properties of the glass samples in this experiment are mainly related to the following two aspects: on the one hand, in the case of introducing out-of-network bulk ions into the glass structure, the ^Q3 structural unit can make the silicon-oxygen tetrahedron [SiO ₄ ] The damage suffered is the least, thus ensuring the stability of the glass network structure. When an appropriate amount of Sr ²⁺ enters the glass network and acts as a network modifier (accumulating the glass network), it is located at the interstitial sites of the tetrahedral network near the negatively charged non-bridging oxygen (NBO), because its ionic radius is larger than that of Li ⁺ , Na ⁺ , K ⁺ and the cationic electric field strength (Z/r ₂ ) are also large, so that the binding force between Na + , K + and the non-bridging oxygen bond is greater than that of Na ⁺ , K ⁺ and the non-bridging oxygen bond. Under the action of the external electric field, Sr ²⁺ can effectively block the migration and vibration of Li ⁺ , Na ⁺ , K ⁺ , thereby reducing the dielectric loss. On the other hand, the increase of ^Q3 structural units can increase the distribution uniformity of the out-of-network cations located around the negatively charged NBO, thereby reducing the structural stress caused by the inhomogeneous composition. At the same time, Sr ₂₊ also acts as a charge balancer in the glass micro-network structure _[58] , neutralizing with the tetrahedral [A1O ₄ ] ^5- phase under the action of Coulomb force, reducing the charge stress and improving the glass's properties. Density thereby increasing the mechanical strength of the photosensitive glass sample.

From the test results of SrO doped series samples, it can be seen that within the doping range of 0wt% to 2wt%, the dielectric properties have a minimum value and mechanical properties have a maximum value, and as the SrO doping content exceeds 1wt%, the The overall dielectric properties and mechanical properties have a tendency to deteriorate, indicating that the doping range should be controlled within 1 wt%.

Since Mg, Ca, Sr, and Ba belong to the same group of elements and they are all external ions in the glass network, the modification principles for the glass network are basically the same, but their properties (cation field strength, ionic radius, etc.) are slightly different. The modified strength of the glass network will also vary. Therefore, the original glass sample S ₀ was doped with Mg, Ca, and Ba respectively, and the influence of each alkaline earth metal on the glass performance was verified according to the above method, and then the two alkaline earth metals that improved the glass performance the best were selected. The metals are MgO and CaO. The original glass sample S ₀ was then doped with different contents of MgO and CaO respectively, and finally the optimal types and proportions of alkaline earth metals were obtained: 0.5 parts of CaO and 0.5 parts of MgO were used for alkaline earth metals.

Li-Al-Si photosensitive glass is prepared by the above-mentioned preparation method of Li-Al-Si photosensitive glass, and the molar amounts of Si ⁴⁺ , Al ³⁺ and O ^2- in the glass satisfy: 1:2<(Si+Al ):O<1:2.5

The quality of the glass micro-network structure determines the quality of its macroscopic properties, and the glass network structure is mainly directly related to the content of each chemical component, so the appropriate chemical component distribution ratio is to obtain a stable and strong glass network. Base. The optimization idea of the chemical composition ratio of the Li-Al-Si photosensitive glass of the present invention is derived from the quartz glass network structure, because the latter has excellent dielectric properties, the dielectric constant is 3.7-3.9, and the dielectric loss is in the order of ^10-4 . In the quartz glass network structure (see Figure 1), there are basically Si-O-Si bridge oxygen bonds with larger bond energy and no extra-network bulk ions with higher mobility, and Si in each [SiO ₄ ] tetrahedron :O=1:2 (molar ratio); and in the Li-Al-Si photosensitive glass network structure, the introduction of alkali metals and other oxides will inevitably cause the breakage of part of the bridge oxygen bonds and form Si- O non-bridging oxygen bonds as well as network voids exist out of the network such as Li ⁺ , Na ⁺ , K ⁺ and free O ^2- . If the number of non-bridging oxygen bonds is too large, the skeleton of the glass network will be loosened, which will lead to a series of performance deterioration. In order to minimize the damage to the integrity and symmetry of the [SiO ₄ ] tetrahedron, ideally, there should be at most one non-bridging oxygen bond in the damaged [SiO ₄ ] tetrahedron (see Figure 2), then this When Si:O=1:2.5 (molar ratio) in the tetrahedron. Therefore, when designing the chemical composition ratio of the glass, in order to minimize the damage of non-bridging oxygen, the number of oxygen ions in the glass network must be controlled, so the molar amount of the glass network generator Si ⁴⁺ and the intermediate Al ³⁺ The sum and the molar amount of O ^2- provided by all oxides satisfy the following inequality:

1:2<(Si+Al):O<1:2.5

This formula is realized by the ratio of each component.

Example 1

Prepared using the following raw materials in parts by weight:

The preparation process is:

Using the melting curve shown in Figure 16: uniformly mix the raw materials and heat the raw materials, so that the raw materials are heated to 800-900 °C within 150-180 minutes, and gas and opaque sintered products are produced;

Continue to heat the raw materials, so that the raw materials are heated to 1200-1250 ° C within 70-100 minutes, and the sintered material begins to melt and gradually becomes transparent;

Continue to heat the raw materials, so that the raw materials are heated to 1400-1500 ° C in 30min-70min, the viscosity of the glass liquid is reduced, and gaseous impurities are released at the same time, so that the glass liquid is clarified;

The glass liquid is kept at a temperature of 1400-1500 ℃ for 100-200 minutes, so that the components are evenly distributed;

The glass liquid is cooled by 150-250° C. within 30-70 minutes, and then the glass liquid is quenched to 200-300° C. within 20-50 minutes to obtain glass.

Annealing, using the annealing curve shown in Figure 17: the initial temperature of the annealing furnace is 470 ~ 500 ° C, and then the temperature is reduced to 180 ~ 220 ° C at a speed of 0.11 ° C / min ~ 0.143 ° C / min, and finally at 500 ~ 800min Cool to room temperature inside.

The prepared Li-Al-Si photosensitive glass was sampled, and the two sides of the sample were coated with circular electrodes with a uniform thickness of 6 mm, then placed in an oven to dry, and then placed in a high-temperature dielectric tester. The test procedure is: test The voltage is 1V, the test frequency is 1GHz, the temperature range is from 25°C to 300°C, the heating rate is 4°C/min, and the temperature deviation is ±0.30°C. Thus, the relationship between dielectric constant and dielectric loss with temperature at a specific frequency is measured.

SANSCMT-6104 bending tester and three-point bending loading method were used to test the bending strength of 4mm×4mm×50mm strip glass samples, and measure the Vickers hardness and expansion coefficient of the samples.

The test results compared with the existing SCHOTT Foturan photosensitive glass are shown in the following table:

It can be seen that the mechanical properties of the Li-Al-Si photosensitive glass prepared by the present invention are better than the Foturan photosensitive glass of Schott, and the dielectric loss is far lower than the Foturan photosensitive glass of Schott, and the overall performance has been greatly improved. Can be used in high frequency environment. In addition, due to the improvement of mechanical properties, it can adapt to the development trend of miniaturization of integrated circuit packages. At the same time, it is beneficial to improve the situation that domestic adapter board materials rely on foreign manufacturers, reduce the cost of domestic three-dimensional integrated packaging, and better promote the development of domestic integrated circuits.

Claims (8)

1. The preparation method of the Li-Al-Si photosensitive glass is characterized by comprising the following steps of:

   
2. 2. the method for producing a Li-Al-Si photosensitive glass according to claim 1, wherein the alkaline earth metal includes one or more of MgO, CaO, BaO, and SrO.
3. 3. The method of producing a Li-Al-Si photosensitive glass according to claim 2, wherein the alkaline earth metal includes MgO and CaO.
4. 4. The method of producing a Li-Al-Si photosensitive glass according to claim 3, wherein the alkaline earth metal includes 0.5 parts of CaO and 0.5 parts of MgO.
5. 5. The method for producing a Li-Al-Si photosensitive glass according to claim 1, comprising the steps of:

   uniformly mixing the raw materials and heating the raw materials to raise the temperature of the raw materials to 800-900 ℃ within 150-180 min, so as to produce gas and opaque sinter;

   continuously heating the raw materials to enable the temperature of the raw materials to rise to 1200-1250 ℃ within 70-100 min, and enabling sinter to start to melt and be gradually transparent;

   continuously heating the raw materials, heating the raw materials to 1400-1500 ℃ within 30-70 min, reducing the viscosity of the molten glass, and releasing gaseous impurities to clarify the molten glass;

   the glass liquid is kept warm for 100-200 min at the temperature of 1400-1500 ℃ so that all components are uniformly distributed;

   cooling the glass liquid within 30-70 min to 150-250 ℃, and then quenching the glass liquid to 200-300 ℃ within 20-50 min to obtain glass;

   and (6) annealing.
6. 6. The method of producing a Li-Al-Si photosensitive glass according to claim 5, wherein the annealing process is:

   the initial temperature of the annealing furnace is 470-500 ℃, then the temperature is reduced to 180-220 ℃ at the speed of 0.11-0.143 ℃/min, and finally the annealing furnace is cooled to the room temperature within 500-800 min.
7. The Li-Al-Si photosensitive glass characterized by being produced by the method for producing a Li-Al-Si photosensitive glass according to any one of claims 1 to 6.
8. 8. The Li-Al-Si photosensitive glass according to claim 7, wherein Si in the glass⁴⁺、Al³⁺And O^2-The molar amount of (A) satisfies: 1:2<(Si+Al):O<1:2.5。

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