Storage of soybean seeds: Packaging and modified atmosphere technology

ABSTRACT The characteristics of materials used in packages for seed storage may have a negative influence in the deterioration process, causing future problems during the period of storage and in emergence in the field. In this study, the objective was to evaluate the physiological quality of soybean seeds, stored in different packages with and without the addition of CO2 (modified atmosphere), for different periods of storage and in uncontrolled environmental conditions. In order to carry out the experiment, a completely randomized design was used in a split-plot scheme, with three types of packages (permeable, hermetic package inside the permeable package and hermetic package inside the permeable package with CO2 injection) in the main plot and six storage periods (zero, 45, 90, 135, 180 and 225 days) in the subplot, with four repetitions, totaling 72 experimental units. In hermetic packages multi-layer paper was used with or without CO2 injection, stored them for 225 days and performed an assessment at regular intervals of 45 days. At each period, the seeds were submitted to tests for moisture content, germination, seedling emergence, accelerated aging and electrical conductivity. The hermetic package, with and without CO2 injection, decreases the speed of deterioration of soybean seeds. The hermetic package allows a higher physiological quality of soybeans compared to the permeable package, with a storage period of up to 180 days under uncontrolled environmental conditions. The addition of CO2 inside the hermetic packages favors the maintenance of the physiological quality of soybean seeds in storage.

Swing Touch Risk Assessment of Bonding Wires in High-Density Package Under Mechanical Shock Condition

Long bonding wires may swing significantly and touch with adjacent ones, which will result in short circuit under mechanical condition, especially in aerospace applications. This may seriously affect the operational reliability of high-density hermetic package components. The aim of this paper is to assess the touch risk of high-density package component under mechanical shock condition. An experiment setup, which can obtain the touch critical load and detect the wires swing touch through voltage signal captured by oscilloscope, is designed and built. To obtain the vibration data of different bonding wire structures under different shock loads, numerical simulation models are established after verified by the experimental data. Additionally, initial swing amplitude model, vibration frequency model, and damped coefficient model are established based on the simulation and experiment data. Furthermore, wire swing touch risk assessment model is established in consideration of the distribution of wire structure and shock load deviation. Based on the verified numerical simulation model, vibration characteristic parameters, including the initial swing amplitude, vibration frequency, and damped coefficient, can be calculated by numerical simulation and experimental results. The proposed method can be used to assess bonding wire touch risk in high-density hermetic package quantitatively. Potential touch risk, which cannot be reflected by failure analysis of structure damage after test, can also be detected by the electronic measurement designed in this paper. The proposed method can effectively reflect short circuit between long bonding wires of hermetic package in large shock applications, such as transport and launch.

Hermetic package for optical devices using room temperature welding technology and transparent lid, for space applications

The objective of the study was to develop a hermetic package for optical devices, with a transparent lid. A novel room temperature glass welding technology was used for the construction of the packages. The design solution and technology must be robust enough for use in space flight applications. Environmental and hermeticity tests were performed to evaluate the package capability & quality. Whilst initially targeted on a specific requirement, there are several industrial sectors that require hermetic encapsulation including; space, military, biotechnology, and telecoms etc. It is common for the space industry for packages, assemblies or even space craft, to be stored before use, driving the stringent hermeticity requirements, to prevent degradation issues when ground testing, integrating or operating in a space environment. The design and technology of the glass package proved to be robust: environmental tests had no influence on the functionality or properties. Other benefits of the laser welded glass package were also discovered: hermeticity, easy failure analysis and inspection due to the lid and package transparency, and mountable design onto a PCB (printed circuit board). Welding technique offers a quick, one-step, room temperature process without any additive materials.

Composition and Form: How Feedthrough Design Affects Package Hermeticity

Ceramic-insulated feedthroughs have been in use in microelectronic packages for decades. Their track record is generally good, but not unblemished. This is because ceramic insulators tend to crack under stress - the stress of assembly temperatures, thermal shock screening and fine leak pressurization. The cracks often propagate to surface termination, forming leak paths and rendering afflicted packages non-hermetic. Package manufacturers have long battled this phenomenon and developed a number of creative designs that attempt to prevent, minimize and/or contain this inherent vulnerability. Yet it persists. To successfully prevent this undesired effect, the factors causal to its origination must be identified, understood and eliminated. That is to say, the effects of the constituent components or parts – the package wall, insulator, conductor and brazes – in summation and subtraction, in function and failure, on the integrity and reliability of the whole must be understood in order to design a package robust to thermal and pressural excursions. The optimal design will consist of components with complimentary properties of composition and form; properties that in interaction with one another multiplicatively enhance package robustness and reliability. Any other design will be vulnerable to failure. Herein, the effects of the component properties of composition and form on the structural integrity, reliability and hermeticity of metal cases employing ceramic insulators will be discussed, the primary factors causal to contemporary feedthrough hermeticity failures will be introduced in the form of a simplified force model, an optimization case study will be presented in brief, and currently utilized design features will be objectively compared and assessed.