What does electronic components need to be tested and screened? Detection of electronic circuit components

Date：2022-08-05 15:33:27Views：830

The detection of electronic components is not only an important link to ensure the normal operation of components, but also the most basic work. There are many kinds of components, and their working principles and technical characteristics are different. In practical work, different detection methods should be selected for different components. In the screening of electronic components, we should pay attention to quality control, overall consideration, scientific selection, simplified design, rational use of performance parameters of components, and give full play to the function of electronic components. Make reasonable selection according to favorable conditions, simplify the circuit design and improve the reliability, and reduce the rating to improve the reliability.

1、 Check the appearance quality

This is a simple and feasible inspection method, which can find the early defects of some electronic components and the damage in the procurement process. The identification and detection of electronic components shall be carried out as follows:

1) Check that the model, specification, manufacturer and origin of components must comply with the design requirements, and the outer packaging must be intact.

2) Check that the appearance of components must be intact, and the surface must be free of dents, scratches, cracks and other defects. Components with coating on the outside must be free of falling off and scratches.

3) The electrode leads of components should be free of crimping and bending, and the coating should be intact and bright without oxidation and corrosion.

4) The model and specification marks on the components shall be clear and complete, the color mark position and color shall meet the standard, and the characters on the integrated circuit shall be carefully checked.

5) The components of the mechanical structure shall be qualified in size, flexible in thread and suitable in rotation.

6) The switch components are flexible and feel good; The connector shall have proper tightness and good contact. The components in various electronic products have their own characteristics, and the inspection content should be determined according to the specific requirements of each component.

2、 Electrical performance screening

In order to ensure the stability and reliability of electronic products, it is an important link to screen the components of the computer. During screening, one or more stresses should be applied to electronic components to expose their defects and eliminate early failure according to the use requirements of components. The screening test and stress application should be in an appropriate range to make the defective components invalid, and the components with good quality will pass the test.

1. Component efficiency curve

The efficiency curve of electronic components, that is, the bathtub curve, reflects the failure law of components in use. Generally, when the components are just put into use, the failure rate will be high due to the defects of raw materials, equipment, technology and so on in the manufacturing process of components. After using components for a period of time, the failure rate of components is low, that is, accidental failure period. After the normal service period, the components enter the aging failure period, that is, the loss failure period. The working life of the components ends in the aging failure period, and the failure rate of the components increases.

2. Screening and aging of electronic components

For the aging screening of components, the early working conditions of components should be artificially manufactured, so that the components are in the simulated working state, and the early failure products should be removed before use to improve the reliability of products. In the production process, screening aging includes high temperature storage aging, high and low temperature cycle aging, high and low temperature impact aging and high temperature power aging. With the improvement of the production level of components, different aging screening requirements and processes should be selected according to different product requirements and national and enterprise standards. For typical components used in electronic products or equipment with high reliability requirements, 100% screening is required. For components used in civilian products with low requirements, sampling inspection method should be adopted; Natural aging and simple electrical aging shall be adopted for the components used in the development and manufacturing of general electronic products.

3. Parameter performance test

After the appearance inspection and aging of electronic components, the performance index shall be tested to eliminate the expired components. Before testing, you should have a comprehensive understanding of the common problems and solutions in the testing of electronic components. It is required to have a variety of general or special testing instruments. General electronic design or components used in electronic equipment should be tested by common instruments such as multimeter. When using a multimeter for testing, pay attention to the use requirements of the multimeter and use it correctly.

1) General multimeter has analog pointer type and digital type. The former is reliable, durable and intuitive, but the reading is inaccurate and the resolution is low; The latter has accurate and intuitive reading, high input resistance and high requirements for use and maintenance.

2) When using the two kinds of multimeter, it is required to select the function and Jack: the pointer type generally has a special jack when measuring high current and high voltage; Special jacks are used for digital measurement of current above 200mA, and special jacks are used for current gears of some models of multimeter.

3) When selecting the measuring range, it should be noted that the indication of the pointer multimeter has a small error at about 30% ~ 35% and 65% ~ 70% of the full scale. If the measured range is difficult to determine, it shall be gradually converted from the maximum range.

4) When using the multimeter, the human body shall not touch the metal part of the probe to ensure accurate measurement and personal safety.

5) When measuring high voltage or large current, do not shift gears during measurement. Disconnect the probe when shifting gears, and connect the probe after selecting the range to measure, otherwise the multimeter will be damaged.

6) The polarity of the measuring diode, rectifier, triode, aluminum electrolytic capacitor and other components with polarity shall be noted. In the resistance gear, the red probe of the pointer multimeter is connected to the negative pole of the internal power supply of the multimeter, the black probe is connected to the positive pole of the internal power supply, the red probe of the digital multimeter is connected to the positive pole of the internal power supply of the multimeter, and the black probe is connected to the negative pole of the internal power supply.

When the multimeter cannot meet the test requirements, the LRC handheld bridge should be used to measure the resistance, capacitance, inductance, quality factor and other parameters, and the combined multimeter should be used to measure the voltage, current, resistance, frequency and other parameters. Hand held bridge and desktop multimeter are selected to measure relevant parameters. The test accuracy is higher than that of multimeter, and it also has the measurement function that multimeter does not have.

The above are the screening and testing methods of electronic components. The testing service scope of Chuangxin testing company covers: testing and verification of electronic components, identification of IC authenticity, product design and material selection, failure analysis, functional testing, factory incoming material inspection, braiding and other test items. Welcome to call Chuangxin testing, and we will serve you wholeheartedly.