Antonio Bonucci

B-DRY®: Edge sealant for sensitive photovoltaic modules

Moisture permeation inside modules is one of the major issues accounting for the degradation of different components in the photovoltaic technology. B-Dry®i is a new edge sealant able to block the moisture penetration both in damp heat accelerated tests and in real operative conditions. Moreover, mechanical resistance and adhesion must be ensured beyond the regulation requirement. B-Dry® has been developed to respect hard aging tests such as Miami UV, damp heat and thermal cycling also for the structural property.

A new model for vacuum quality and lifetime prediction in hermetic vacuum bonded MEMS

In many MEMS applications the level of vacuum is a key issue as it directly affects the quality of the device, in terms of response reliability. Due to the unavoidable desorption phenomena of gaseous species from the internal surfaces, the vacuum inside a MEMS, after bonding encapsulation, tends to be degraded, unless a proper getter solution is applied. The in situ getter film (PaGeWafer®) is recognised to be the most reliable way to get rid of degassed species, assuring uniform, high quality performances of the device throughout the lifetime. Moreover, post process vacuum quality control and reliability for hermetic bonding is extremely important for overall device reliability and process yield. In this paper we will discuss the main factors that are critical in the attainment of vacuum and will present a novel calculation model that enables the prediction of vacuum level after bonding, making also possible the estimate of the lifetime. Furthermore, a new analytical method based on the residual gas analyses (RGA) will be presented that gives the main characteristics of the materials. Modeling and simulation work support the process optimization and system design.

The Transmission Factor Method: in‐situ Characterization of Getter Coated Pipes

Particle accelerators and synchrotron light source need low residual pressure during operating conditions. In specific applications like narrow‐gap insertion devices, NEG coating has proved to be very effective. ASTM F798‐82 standard is the common characterization method for the sorption performance of getters. In the case of getter coated pipes, the measurement is conducted “offline” on a sample (coupon), suitably positioned inside the chamber to be coated and removed after the process. Although this approach is suitable to guarantee the control of the process, in‐situ characterization should be useful to evaluate residual pressure during the operating conditions. A different measurement technique (Transmission Factor Method) is here described. It is based on the measurement of pressures ratio at the inlet and the outlet of a coated pipe, under a flow of test gas. A calibration curve is calculated using a modellistic approach and permits to evaluate sticking probability of the coated surface from the pressure ratio. Preliminary experimental results about the characterization of this getter will be shown. Keywords: Getter sorption measurement.

Pumping characteristics of metal films in a vacuum glass vessel: Experimental and theoretical issues

The evaluation of the pumping characteristics of metallic films deposited onto glass surfaces in a vacuum environment is a very important issue for several industrial and research applications. Many years ago, an optimized experimental setup and method were defined to measure the pumping characteristics of barium films inside cathode ray tubes (CRTs). [P. della Porta and F. Ricca, Advances in Vacuum Science and Technology (Pergamon, New York, 1960), Vol. II, p. 661 and P. della Porta and L. Michon, Vacuum 15, 536 (1965)]. However, some technological limitations, related both to the particular experimental configuration and to the method used, prevented the possibility of extending this approach to a more general case, including adsorbing materials different from barium, deposited onto surfaces having a geometry different from that of a CRT. The progress in vacuum technology makes it possible today to use a large variety of components to assemble an experimental vacuum apparatus. Moreover, the availability...

Outgassing and Gettering

Outgassing is an unavoidable issue and although the cleaning process and long baking are carried out, the effect can be limited only by using the getter technology. This technology absorbs the residual gases trapped in the device during the process and maintains the pressure at a very low level for the required lifetime, limiting the gas flux. It has been described that there are gases remaining inside MEMS devices that need a vacuum or other stable pressure to operate properly. The MEMS packaging technology moved from hermetic vacuum discrete packages to vacuum wafer-level packages. Conventional packaging of microelectronic and optoelectronic devices is usually stable and not affected by the external environment except for a few specific cases. Vacuum wafer-level packaging is a very effective technique to produce low-cost, hermetically sealed packages for micromachined sensors and actuators. The main contamination source is the leakage and outgassing phenomena. The leakage is mainly caused by defects in the bonding frame and can be solved by a suitable improvement of the technology or accepting a limited yield in the MEMS production. In the case of outgassing a technically viable solution to assure a long lifetime and high reliability to MEMS device is the integration of a getter film. This has also been explained in detail.

Photo-active integrated getters for stable dye-sensitized solar cells

Linde Type A with Na cation (LTA-Na) nanozeolite-based TiO2 photoanodes have been implemented in dye-sensitized solar cells introducing the concept of an integrated getter. These innovative structures improve the device stability thanks to their ability to neutralize the moisture effect, while also acting as active scattering centers.

Lifetime prediction in vacuum packaged MEMS provided with integrated getter film

Thin-film getter integration is one of the key technologies enabling the development of a wide class of MEMS devices, such as IR microbolometers and inertial sensors, where stringent vacuum requirements must be satisfied to achieve the desired performances and preserve them for the entire lifetime. Despite its importance, the question about lifetime prediction is still very difficult to answer in a reliable way. Here we present an experimental approach to the evaluation of lifetime, based on an accelerated life test performed varying both the storage conditions and the getter area. A test vehicle based on a resonator device was used. The hermeticity was evaluated by means of specific leak testing, while MEMS behavior during the ageing test was studied monitoring device functional parameters and by residual gas analysis (RGA). Unexpected results were observed leading to the discovery that methane is pumped by the getter below 100°C. These results served as the inputs of a suitable model allowing extrapolating the device lifetime in operating? conditions, and pointed out that RGA is an essential tool to correctly interpret the aging tests.

Chapter Forty – Outgassing and Gettering

Publisher Summary Outgassing is an unavoidable issue and although the cleaning process and long baking are carried out, the effect can be limited only by using the getter technology. This technology absorbs the residual gases trapped into the device during the process and maintains the pressure at very low level for the required lifetime, limiting the gas flux. It has been clearly described that there are gasses remaining inside MEMS devices that need a vacuum or other stable pressure to operate properly. The MEMS packaging technology moved from hermetic vacuum discrete packages to vacuum wafer-level pack- ages. Conventional packaging of microelectronic and optoelectronic devices is usually stable and not affected by the external environment except for a few specific cases. Hydrogen Vacuum wafer-level packaging is a very effective technique to produce low-cost, hermetically sealed packages for micromachined sensors and actuators. The MEMS devices requiring a vacuum to operate properly are shown in pressure level is a key parameter for the quality of the MEMS devices. The main contamination source is the leakage in the bonding and outgassing phenomena. The leakage is mainly caused by defects in the bonding and can be solved by a suitable improvement of the technology or accepting a limited yield in the MEMS production. A technically viable solution to assure a long lifetime and high reliability to MEMS device is the possibility to integrate a getter film. This has also been explained in detail.

12.2: Characterization of Dryers for OLED/PLED Applications

Experimental methods for the characterization of dryers for OLED/PLED applications were addressed and results are reported and compared. Different commercially available dryers were tested. It turned out that test conditions can significantly affect the results of the characterization. For example, dryers showing a low total theoretical capacity can, on the contrary, show very good performances if tested using methods and conditions closer to the operating conditions expected to occur inside OLED/PLED devices. The measured sorption performances were used to calculate how water concentration inside a display evolves during lifetime of the device itself. These calculations show the effect and the benefit that can be obtained by the use of a specific dryer. Different measurement methods were compared and considerations for the selection of a suitable charachterization test are given.

P-235L: Late-News Poster: Analysis of the Relationship Between OLED Performance and Dryer Characterization

The successful exploitation of OLED/PLED displays is dependent on the control and removal of moisture from the device. Pixel shrinkage and luminosity reduction during the operating conditions are the most relevant issues, related to the moisture concentration into the device. Results show a strong link with dryer absorbing speed more than total capacity, as forecasted by a suitable model.