Solder Glass Research Articles

Low Temperature Sealing Process and Properties of Kovar Alloy to DM305 Electronic Glass

The low temperature sealing of Kovar alloy to DM305 electronic glass was realized by using lead-free glass solder of the Bi2O3-ZnO-B2O3 system in atmospheric environment. The sealing process was optimized by pre-oxidation of Kovar alloy and low temperature founding of flake glass solder. The effects of sealing temperature and holding time on the properties of sealing joint were studied by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), etc. The results showed that the pre-oxidized Kovar alloy and DM305 electronic glass were successfully sealed with flake glass solder at the sealing temperature of 500 °C for 20 min. Meanwhile, the joint interface had no pores, cracks, and other defects, the shear strength was 12.24 MPa, and the leakage rate of air tightness was 8 × 10−9 Pa·m3/s. During the sealing process, element Bi in glass solder diffused into the oxide layer of Kovar alloy and DM305 electronic glass about 1 μm, respectively.

Joining dense Si3N4 to porous Si3N4 by using an anorthite based glass-ceramic

This study focuses on the design, characterization and testing of a novel anorthite based glass-ceramic solder for joining dense Si3N4 and porous Si3N4 ceramic. It was found that the glass solder possesses a favorable wetting ability on two ceramic surfaces. Additionally, the influence of crystallization treatment on the microstructure and shear strength of joints was investigated. The results showed that CaAl2Si2O8 was the main product in the seam. After crystallization treatment, the crystallinitiy of the seam and shear strength of joints were improved obviously. The shear strength of joints after crystallization was 52 MPa at room temperature, and it increased to 59 MPa at 850°C. Finally, the joining mechanism of the dense Si3N4/glass-ceramic/porous Si3N4 bonded joints was proposed. Intergranular diffusion of elements was identified as the main mechanism of bonding in the interface of dense Si3N4/glass-ceramic. In the porous Si3N4 side, the bonding was achieved by infiltration that was controlled by capillarity and resistance of the viscous forces.

Reverse Manufacturing Enables Perovskite Photovoltaics to Reach the Carbon Footprint Limit of a Glass Substrate

Summary Although it still contributes to less than 2% of the worldwide electricity generation, photovoltaics (PVs) is on the way to becoming a key energy technology for a global future renewable energy infrastructure. We present projections of worldwide CO2 emissions of the future PV industry, finding that these emissions will likely surpass those caused by the global shipping or aviation sector. As an alternative, we propose a fully printed PV reverse manufacturing concept that minimizes the carbon footprint to the ultimate lower limit of the glass substrate fabrication. This so called “in situ” approach is based on a perovskite absorber that is highly durable and encapsulated with glass solder between float glass substrates, reducing the CO2-footprint of conventional PV modules by 1/20th. Yielding a certified stabilized efficiency of 9.3%, this record efficiency for glass-solder-encapsulated perovskite PV paves the way for future solar cells with the lowest carbon footprints.

Development and characterization of inks for screen printing of glass solders for SOFCs

AbstractGlass ceramics are supposed to produce stable sealants between ceramic electrolyte and ferritic steel in planar SOFC stacks. The screen printing method is a suitable industrial process in order to produce layers with tailored height and width reproducibly. An appropriate suspension was developed for this application and improved by adjusting the additive composition. This study investigates the rheological behavior of screen printing inks and the corresponding topography of the printed layers. Rotary measurements were carried out to analyse the impact of shear rates on viscosity showing shear thinning behavior. In addition, oscillatory rheometry is performed to gain information about the viscoelastic properties of the slurries and to understand the internal structure of the developed inks. The viscoelasticity and the recovery behavior after shear loading are crucial for the topography of printed films. The principal investigations are executed on solvent‐based suspensions, whereby the knowledge gained is used for a transfer to water‐based systems allowing a more environmentally friendly handling.

Effect of Gamma Irradiation on High Lead Borate Glass Doped with Tungsten Oxide

X-ray, Ultraviolet and Fourier Transform infrared spectral properties of tungsten ions doped in a host lead borate glass have a composition [60%PbO and 40%B2O3 weight%] was studied. Effect of gamma irradiation on the prepared glass samples was surveyed. Amorphization of the studied glass samples have been checked by X ray. Deep inspection for density, molar volume, UV and FTIR for base glass and tungsten oxide with different concentrations (0.15-2.28) weight% proved that the tungsten ions are pronounced as structural groups mostly in the hexavalent W6+. The constancy of optical absorption spectral curves reversed the shielding behavior for this combined glass towards successive gamma irradiation. Glasses containing high lead oxide content are extensively used for multi-applications including lead crystal glass and some special optical glasses, low-melting solder glasses and radiation protection windows and even in immobilization of radioactive nuclear wastes.

Thermal Transmittance around Edge of Vacuum Glazing

The main objective of the calculations thermal performance properties of the edge of vacuum glazing was the quantification of the heat flow around edge of glazing. Additional heat flow around edge of glazing is expressed by means linear thermal transmittance. Linear thermal transmittance of the junction between edge vacuum glazing and wooden frame or wooden-aluminium frame was calculated by using a two dimensional (2D) numerical calculations. Edge sealing of vacuum glazing is assumed by means solder glass with Indium metal strip, so it is metal-based edge seal. In vacuum glazing the edge seal acts as a thermal bridge between the glass sheets. Heat? ows from the glass sheet on the warm side through the edge seal to the sheet on the cold side, not only does it increase the overall thermal performance of the glazing, but also it causes temperature variation (decrease surface temperatures) and stress in the edge region.

Experimental Research on Sensing Characteristics of Adhesive-Encapsulated FBG Under Alcohol-Disinfection Environment

Fiber Bragg grating (FBG) has proven to be the most suitable sensing element for force feedback of surgical robots because of its special advantages such as small size and physical robustness. In current reports, the researchers packaged FBGs in a surgical instrument by attaching them to an external surface or by embedding them into the shaft grooves using an adhesive because the adhesive has good liquidity and operability compared to other packaging methods, such as metal package and glass solder package, and is often not covered due to the strict space requirement of tiny surgical instruments. However, for repeated disinfection, surgical instruments have to be excessively exposed to chemical disinfectants, which may lead to chronic corrosion of the adhesive, thus influencing the sensing characteristics of the integrated FBGs. To address this concern, this paper investigates the sensing characteristics of the adhesive-encapsulated FBG under disinfection environment. We simulated a common disinfection environment using 75% alcohol, in which three adhesive-encapsulated FBGs were soaked for a long term. The sensing performances of FBGs have been tested periodically, and the experimental results demonstrate that the FBGs have good sensing characteristics within first 50 days. However, after 50 days, the sensing performances of the three FBGs worsened gradually, and, finally, the adhesive layers of the three FBGs completely detached from the specimen in the 75th day, 80th day, and 95th day, respectively. We hope the investigation could provide a valuable reference for better application of the FBG in force feedback of surgical robots.

Microstructure and mechanical properties of tempered glass joint bonded with Bi-B-Zn low melting glass

Soda lime tempered glass was successfully joined by a Bi-B-Zn lead-free low-melting glass with a composition of 35Bi2O3-50H3BO3-15ZnO (mol%). The Bi-B-Zn glass exhibited a glass transition temperature (Tg), softening point (Td) and crystallization temperature (Tc) of 346 ℃, 364 ℃and 448 ℃ respectively. The wettability of the glass on tempered glass substrate was investigated, and a contact angle of less than 13.94° was obtained when the temperature was raised to above 470 ℃ in open atmosphere. The microstructural evolution, interfacial bonding mechanism and mechanical properties of the joint at different joining temperatures were investigated. The diffusion bonding between Bi-B-Zn glass solder and tempered glass was achieved. The crystals of Bi4B2O9 were detected in the joint when the joining temperature was higher than 450 ℃. The shear strength and Vickers hardness of the joint reached 35.14 ± 1.89 MPa and 191.55 ± 13.93 MPa, respectively. The effects of the fractions and size of Bi4B2O9 on the shear strength were evaluated, and the fracture mechanism at the interface was also clarified.

Analysis of red mud doped Bi2O3-B2O3-BaO glasses for application as glass solder in radiation shield repair using MCNPX simulation

Glasses in the range 50Bi2O3-30B2O3-(20-x)BaO-xRedmud, x = 0.1–0.5 wt%, were synthesized and characterized for use as low melting point radiation shield glass solder using a combination of spectroscopic, thermal analysis and MCNPX simulation. The MCNPX general purpose Monte Carlo code was used to determine the Gamma-ray half-value layer (HVL) for several photon energies. The results showed that the HVL and the mass neutron removal cross-section, for neutrons below 15 MeV, of the samples under investigation were comparable to that of the shields used in nuclear reactors as moderators and Gamma-ray shields. The thermal studies of the glass samples showed they remained amorphous over the heating range of 30–1000 °C while at the same time having low softening temperatures and large values of Tc-Tg, indicating high heating rate independent stability. The bulk modulus calculated using bond compression model suggest that the glass system would be ideal to repair currently existing construction material without compromising the structural integrity. Spectroscopic analysis of the glass system showed the presence of BO4 and BO3 units as the major network former while BiO6 acted as an intermediate. The Raman spectrum also showed overlapping bands of SiO4 and B-O vibrations. The Optical absorption showed the presence of various bismuth ions active in both the UV and NIR region. The structural analysis was also complimented by x-ray diffraction (XRD) which showed two halos consistent with the borate network and energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) analysis which showed no major nucleation or crystalline phases. The Fe3+ content of red mud showed the most impact on the molar volume and bond compression bulk modulus of the samples.

Application of ultrasonic assisted soldering method to hard-to-solder material

In this study, Pb-free solders were bonded to soda-lime glass and fused quartz plates using the ultrasonic assisted soldering (UAS) method. The solder–glass interfaces were observed and analyzed to clarify the effect of the elements in the solder and glass bonding behavior. As a result, the Sn–Zn solder was bonded to glass without the intermetallic compound (IMC) layer. However, the Sn–Ag–Cu solder was not able to bond to glass even though ultrasonication was performed during the soldering process. Chemical shifts for Zn 2p and O 1s spectra were observed at the interface by X-ray photoelectron spectroscopy (XPS) analysis, which is attributed to the chemical bonding between the substrates and elements in solder alloy. In conclusion, O in the substrate and Zn in the solder were important to form the bond between the glass and solder.

Microstructure and Properties of Porous Si3N4/Dense Si3N4 Joints Bonded Using RE–Si–Al–O–N (RE = Y or Yb) Glasses

The joining of porous Si3N4 to dense Si3N4 ceramics has been successfully performed using mixed RE2O3 (RE = Y or Yb), Al2O3, SiO2, and α-Si3N4 powders. The results suggested that the α-Si3N4 powders partly transformed into β-SiAlON and partly dissolved into oxide glass to form oxynitride glass. Thus, composites of glass/β-SiAlON-ceramic formed in the seam of joints. Due to the capillary action of the porous Si3N4 ceramic, the molten glass solder infiltrated into the porous Si3N4 ceramic side during the joining process and formed the “infiltration zone” with a thickness of about 400 μm, which contributed to the heterogeneous distribution of the RE–Si–Al–O–N glasses in the porous Si3N4 substrate. In-situ formation of β-SiAlON in the seam resulted in a high bonding strength. The maximum bending strength of 103 MPa and 88 MPa was reached for the porous Si3N4/dense Si3N4 joints using Y–Si–Al–O–N and Yb–Si–Al–O–N glass solders, respectively.

Study on the failure temperature of Ti/Pt/Au and Pt5Si2–Ti/Pt/Au metallization systems**Project supported by the National Natural Science Foundation of China (No. 61376114).

The Ti/Pt/Au metallization system has an advantage of resisting KOH or TMAH solution etching. To form a good ohmic contact, the Ti/Pt/Au metallization system must be alloyed at 400 °C. However, the process temperatures of typical MEMS packaging technologies, such as anodic bonding, glass solder bonding and eutectic bonding, generally exceed 400 °C. It is puzzling if the Ti/Pt/Au system is destroyed during the subsequent packaging process. In the present work, the resistance of doped polysilicon resistors contacted by the Ti/Pt/Au metallization system that have undergone different temperatures and time are measured. The experimental results show that the ohmic contacts will be destroyed if heated to 500 °C. But if a 20 nm Pt film is sputtered on heavily doped polysilicon and alloyed at 700 °C before sputtering Ti/Pt/Au films, the Pt5Si2–Ti/Pt/Au metallization system has a higher service temperature of 500 °C, which exceeds process temperatures of most typical MEMS packaging technologies.

Microstructural Characterisation of Glass Ceramics as a Component Part of High Pressure Discharge Lamps

Abstract The investigation presented is of part of a high pressure discharge lamp. The heart of the lamp is a ceramic burner which is sealed with a so-called glass solder, a glass ceramic comprised of a mixture of Oxides (Dysprosium Oxide, Aluminium Oxide and Silicon Oxide). Two different chemical compositions of glass solder, which are part of type of a composite material comprised of a broad spectrum of materials, are compared microscopically. The morphology of solidification, which has an effect on the operating life of the lamps is characterised using various classical methods such as optical light microscopy and Scanning Electron Microscopy.

The Microstructure Properties of PbO-TiO<sub>2</sub>-SiO<sub>2</sub> System Sealing Solder for Vacuum Glazing

Microstructure properties of PbO-TiO2-SiO2 system sealing solder for vacuum glazing was studied. Sealing solder was placed on the sealing glass substrate. Samples were obtained by sintering at different temperatures. The microstructure properties and binding properties with soda lime glass substrate at different temperatures was observed and studied. Micro hardness of the sealing solder after sintering were tested. The results show that in the solder sealing temperature, a transition layer was formed gradually between the sealing solder and the glass substrate as the sintering temperature increases. PbO and SiO2are main ingredients of the transition layer. This layer performed tight connection with the glass substrate after it was completely formed. The interface between sealing solder and soda lime glass substrate showed good performance. PbO-TiO2-SiO2-RxOy system is an ideal sealing material for the production of vacuum glazing.

Application of Nd2O3–Al2O3–SiO2 glass solder for joining of silicon carbide components

Glasses in the Nd2O3–Al2O3–SiO2 system were prepared using the melt–quench route. Thermal analyses of the prepared glasses were carried out to determine glass transition and crystallisation temperatures. The prepared glass showed surface crystallisation with no sign of bulk crystallisation. After long heat-treatment at 1200°C for 50h in argon atmosphere mullite, Nd-disilicate phases and an unknown crystalline phase were detected by XRD analysis. Furthermore, it was demonstrated that Nd-aluminosilicate glass can be used as solder for joining silicon carbide (SiC) components using laser-assisted process. The optimized used processing conditions produced joints with hermetic tightness (<1×10−9mbarls−1) and an average 4-point bending strength of 150MPa. Fracture analyses did not show fracture along the SiC/glass interface that indicates the good adhesion of the solder glass with SiC surface.

A Novel Technique for the Connection of Ceramic and Titanium Implant Components Using Glass Solder Bonding.

Both titanium and ceramic materials provide specific advantages in dental implant technology. However, some problems, like hypersensitivity reactions, corrosion and mechanical failure, have been reported. Therefore, the combining of both materials to take advantage of their pros, while eliminating their respective cons, would be desirable. Hence, we introduced a new technique to bond titanium and ceramic materials by means of a silica-based glass ceramic solder. Cylindrical compound samples (Ø10 mm × 56 mm) made of alumina toughened zirconia (ATZ), as well as titanium grade 5, were bonded by glass solder on their end faces. As a control, a two-component adhesive glue was utilized. The samples were investigated without further treatment, after 30 and 90 days of storage in distilled water at room temperature, and after aging. All samples were subjected to quasi-static four-point-bending tests. We found that the glass solder bonding provided significantly higher bending strength than adhesive glue bonding. In contrast to the glued samples, the bending strength of the soldered samples remained unaltered by the storage and aging treatments. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analyses confirmed the presence of a stable solder-ceramic interface. Therefore, the glass solder technique represents a promising method for optimizing dental and orthopedic implant bondings.

Adhesive Bonding of Oxide Ceramics for Complex Ceramic Parts in High Temperature Furnaces

Within the scope of the project ENERTHERM: Energy efficiency of thermal processes which is funded by the Bavarian Ministry of Economy (BMWi) components and systems for high-temperature are being developed. Monolithic oxide ceramics (mullite, Al2O3) and oxide-fiber reinforced ceramics (O-CMC) show a high potential for high temperature (HT) applications. Additionally, the demand for complex HT-components such as HT-fanwheels for kilns, supporting HT-lightweight structures or hot gas liners increases. In according to the required component design, joining techniques are needed in order to realize such complex geometries. The generated joints were made by using commercial glass solder from the type Al2O3-SiO2-MgO. For realizing the joining process sintering-joining in HT-kilns was used because of the homogeneous temperature distribution. A CO2 laser (wavelength of 10.6 microns and a power of 1.5 kW) was used for rapid joining process. The mechanical properties were determined in according to DIN EN 843-1 and DIN EN 658-3 (4-point bending strength) and evaluated according to Weibull distribution.

Investigation of microstructure and mechanical property of Li–Ti ferrite/Bi2O3–B2O3–SiO2 glass/Li–Ti ferrite joints reinforced by FeBi5Ti3O15 whiskers

The Bi2O3–B2O3–SiO2 glass solder was used to join the Li–Ti ferrite. SEM micrographs of the joints showed the formation of FeBi5Ti3O15 whiskers at the interface. The formation mechanism was that the elements Fe and Ti reacted with [BiO6] units and came out as needle-like FeBi5Ti3O15 whiskers during cooling when the Ti content in the seam reached the critical concentration of crystallization. The quantity and morphology of the FeBi5Ti3O15 whiskers could be controlled by adjusting the bonding temperature and applied pressure, which could decide the Ti content in the seam. The deciduous ferrite ceramic particles were observed at the interface due to the formation of the FeBi5Ti3O15 whiskers continually consumed the elements Fe and Ti. Under the combined influence of the elements diffusion and interfacial reactions, nearly defect-free joints were obtained and a maximum in the shear strength of 92MPa was achieved at 750°C for 30min under 100Pa applied pressure.

Laser welding of sapphire wafers using a thin-film fresnoite glass solder

Two sapphire substrates are tightly bonded through a fresnoite-glass thin film, by irradiation with a 1,064 nm nanosecond laser. The composition of the glass solder at the bond interface changes, due to incorporation of Al from the upper substrate. The oxidic solder remains amorphous after laser irradiation, but after annealing (850 °C for 1 h) crystalline structures are observed in different morphologies, which are attributed not only to fresnoite, but also to Ba---Ti---Al---O phases, which lead to a strong luminescence of the laser irradiated region under UV excitation.

Design and manufacture of ceramic heat pipes for high temperature applications

Heat exchangers based on ceramic heat pipes were designed for use under highly abrasive and corrosive atmospheres at temperatures in the range of 800–1200 °C for high-temperature power-engineering applications. The presented heat pipes are gravity assisted and based on a multi-layer concept comprising a ceramic cladding and an inner metal tube that contains sodium as the working fluid. Hermetical encapsulation of the working fluid was achieved by electron-beam welding of the inner metal tube. Subsequently, closure of the surrounding ceramic tube was performed by laser brazing technology using a glass solder. Temperature resistance and functionality of the manufactured ceramic thermosyphons could be confirmed experimentally in a hot combustion gas atmosphere at temperatures up to 1100 °C. The ceramic tubes used had an outer diameter of 22 mm and a total length of 770 mm. The measured axial heat transfer of the ceramic gravity assisted heat pipes at the stationary operating point with cold/hot gas temperature of 100 °C/900 °C was 400 W. The result of the calculation using the created mathematical model amounted to 459 W.