Effect of Low-pressure area on product performance reliability test of electronic components

Date：2023-07-19 15:05:00Views：395

1、 Low-pressure area environment

Under the action of Gravity of Earth, the air clings to the earth and forms the atmosphere, which extends from the ground up to hundreds of kilometers high. The gravity of the Earth causes air to have a certain weight, forming atmospheric pressure. The atmospheric pressure at a certain altitude is the weight of the entire air column per unit area perpendicular to the ground above that point.

Atmospheric pressure is isotropic, meaning that at a certain point, the atmospheric pressure is equal regardless of which direction it is measured in. The magnitude of atmospheric pressure mainly depends on altitude. As altitude increases, atmospheric pressure gradually decreases and the atmosphere becomes thinner. At an altitude close to 5.5km, the atmospheric pressure decreases to approximately half of the standard atmospheric pressure at sea level; The atmospheric pressure near 16km is 1/10 of the standard sea level value; The atmospheric pressure near 31km is 1/100 of the standard atmospheric pressure at sea level.

The decrease in atmospheric pressure will inevitably have an impact on the electrical and electronic products used in high-altitude areas. About 50% of the Earth's surface area in China is 1000m above sea level, and about 25% is 2000m above sea level. The larger the pressure gradient, the faster the pressure changes, and the greater the chance of component damage.

2、 Influence of Low-pressure area Environment on Electronic Components

01 Impact on heat dissipation products

Reliability Analysis of Electronic Components in Low-pressure area Environment

A considerable portion of electrical and electronic products are heat dissipation products, such as motors, transformers, etc. These products consume a portion of electrical energy during use, converting it into thermal energy and causing the product temperature to rise. The temperature rise of heat dissipation products increases with the decrease of atmospheric pressure.

The heat dissipation of heat dissipation products can be divided into three forms: conduction, convection, and radiation.

The heat dissipation of a large number of heat dissipation products mainly depends on convection, that is, the heat dissipation depends on the air flow around the product. Convective heat dissipation can be divided into forced ventilation heat dissipation and Natural convection heat dissipation. Natural convection heat dissipation depends on the temperature field generated by the product heating, which causes the temperature gradient of the air around the product and makes the air flow and heat dissipation. Forced ventilation and heat dissipation are measures that force air to flow through the product, taking away the heat generated by the product.

For forced convection heat dissipation, with constant volume flow, atmospheric pressure will decrease with Density of air as the height increases. The decrease of Density of air will directly affect the effect of forced convection heat dissipation. This is because forced convection heat dissipation relies on the flow of gas to carry away heat. Generally, the cooling fan used for motors is to ensure that the volume flow through the motor remains unchanged. When the height increases, the mass flow of the air flow will decrease even if the volume flow remains unchanged due to the decrease of Density of air.

The impact of 02 on the performance of electronic components

The increase in height and the decrease in air pressure will also have an impact on the performance of electronic components. Especially for equipment with air as insulation medium, Low-pressure area has a more significant impact on it. Under normal atmospheric conditions, air is an excellent insulation medium, and many electrical products use air as the insulation medium. When these products are used as mechanical equipment in high altitude areas, partial discharge often occurs near the electrode with strong electric field strength due to the reduction of atmospheric pressure. More seriously, sometimes air gap breakdown occurs, which means that the normal operation of the equipment is disrupted.

3、 Reliability Control of Electronic Components in Low-pressure area Environment

Reasonable selection of 01 components

Designing, analyzing, and reasonably selecting components based on their usage characteristics in circuits is the foundation of component reliability. The reliability control point of electronic components should be moved forward, starting from the source, that is, from design selection, selection of manufacturers, compression of varieties, reliability testing, and improvement of quality level, so that preventive measures that are bought at the cost can play a role at the source, and cannot always be in the state of remedial measures. In addition, from the perspective of physical analysis of component reliability, the quality and reliability analysis technology of components such as collection and analysis of failure information, failure analysis, destructive physical analysis, internal atmosphere analysis of sealed components, correlation analysis of failure mode and mechanism and process, Failure mode and effects analysis should be systematically carried out, and the quality and reliability analysis technology of components should be integrated into the design and manufacturing process of component products, Achieve reliability growth of components.

02 Supervision, testing, and acceptance of components

The production, testing, and acceptance of components are important links to ensure the quality of components, and are also key control points for the reliability of aerospace product components. The quality of process control determines the inherent quality of components. Electronic components are divided by function, including electronic components, discrete devices, and microcircuits; Divided by procurement channels, there are imported and domestic components; Divided by product maturity, there are shelf products and new product components. Different components have different control requirements, and there should be different processing methods and procedures during factory supervision, acceptance, and arrival inspection. Therefore, components should be divided into different categories, and the supervision methods, special test requirements, and acceptance methods for each type of component should be specified, with corresponding procedures and executing units or departments clearly defined.

03 Destructive Physical Analysis

The main purpose of DPA (destructive physical analysis) for components is to prevent the installation and use of components with obvious or potential defects. In addition to being used for quality identification of components, it is also used in aerospace products for component acceptance, pre installation quality review of components, component overdue retesting, and component failure analysis. On general products, DPA is usually used for quality verification of installed components. In aerospace products, DPA must be completed before the installation of components. Therefore, it is necessary to clarify the timing of DPA for components used in aerospace products, the testing items for DPA, the organization implementing DPA, the data recording requirements for DPA, and the processing method for DPA results.

Failure Analysis Method for 04 Components

The main task of component failure analysis is to conduct necessary electrical, physical, and chemical tests on the failed components, and analyze the specific situation before and after the component failure and relevant technical documents to determine the failure mode, failure mechanism, and cause of the component failure. Through failure analysis, the inherent quality issues of failed components can be identified, and it is also possible to discover quality issues in the use of components due to non-compliance with specified conditions. By providing feedback to relevant parties, the responsible party can be urged to take corrective measures to improve the inherent quality or service quality of components.

Relatively speaking, determining the failure mode is relatively simple, while determining the failure mechanism is more difficult. Analysts must master the design, process, and related physical and chemical knowledge of components, and have some practical experience. In addition, it is necessary to have more complex instruments and equipment. After clarifying the failure mechanism, we must find out the Failure cause to avoid repeated failures and improve the inherent quality or use quality of components. However, it is quite difficult to determine the Failure cause according to the failure mechanism, which often involves the failure site and the responsible person.

Therefore, first of all, it is necessary to determine the unit for conducting failure analysis, specify the procedures and information for submitting failure analysis, as well as the requirements for recording failure information of failed components in each stage of product development. Then, based on the conclusions of failure analysis, the cause of failure should be reset to zero. If it is a design defect, it should be identified and improved together with the manufacturer; If it is an operational error, strict operating standards must be implemented to avoid introducing human errors. To achieve the purpose of failure analysis and take device manufacturing and production operations to a higher level.

05 Management of Component Quality Information

In the quality assurance process of component selection, procurement, supervision and acceptance, screening and retesting, and failure analysis, there is a large amount of component quality information, such as the specifications, models, manufacturers, quality levels, and usage in aerospace products of components selected outside the catalog; Domestic manufacturers and usage of new devices; Quality assurance of imported devices; Component failure analysis report and handling situation, etc.

To sum up, Low-pressure area will greatly affect the performance of electronic components, sometimes leading to direct damage.

The impact of Low-pressure area environmental conditions on components cannot be simulated under normal atmospheric conditions, and must be tested according to relevant standards. Therefore, it is necessary to strengthen the standardization of environmental condition testing, consider the impact of environmental changes on the product from the design stage, enhance the adaptability of the product to the environment, and thereby improve the reliability of the product.