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23

2022

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11

How to identify a good or bad integrated circuit (IC)? Do you know?

How to determine the quality of an integrated circuit (IC)? Let's find out together. I. Out-of-circuit testing. This method is performed when the integrated circuit (IC) is not soldered to the circuit. Generally, we can use a multimeter to measure the positive and negative resistance values between the pins corresponding to the system ground pin function, and compare them with a good IC for analysis. II. In-circuit testing. This is a method that uses a multimeter to test the DC resistance, AC/DC output voltage to ground, and total operating current of each pin of the integrated control circuit in the system circuit. This method overcomes the limitations of replacing integrated circuits and the trouble of disassembling integrated circuits, and is a commonly used and practical method for testing integrated circuits. 1. DC operating voltage measurement. This is a method that measures the DC power supply system voltage and the voltage provided for the operation of peripheral electronic devices using the DC voltage block of a multimeter under power-on conditions. Check the DC voltage value of each IC pin to ground and compare it with the normal value to narrow down the fault range and find the damaged components. Pay attention to the following eight points during measurement: (1) The multimeter should have a sufficient internal resistance, less than 10 times the resistance of the circuit being measured, to avoid affecting the measurement system error. (2) Generally, all potentiometers should be turned to the neutral position,

14

2022

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11

Working principle and characteristics of integrated circuit ICs

Integrated circuits (ICs) are not only used commercially, widely applied in consumer electronics such as tape recorders, televisions, and computers, but also extensively used in military, communication, and remote control fields. Because it is impossible to accurately determine whether an integrated circuit (IC) is operating and whether it is the key component in repairing television, audio, or video equipment, and replacing a new integrated circuit (IC) is often difficult and the fault may persist, let's understand the working principle and characteristics of integrated circuits (ICs). I. Working Principle of Integrated Circuits (ICs): 1. Understand the purpose, internal structure, and main electrical characteristics of the integrated circuit (IC) in the circuit, and analyze the internal electrical schematic diagram if necessary. In addition, if the DC voltage, waveform, and positive and negative DC resistance to ground of each integrated circuit (IC) procurement terminal are measured, it can provide more favorable conditions for pre-inspection judgment. 2. Then, judge the location of the fault based on the fault phenomenon, and locate the faulty component based on the location. Several judgment methods are needed to prove whether the device is indeed damaged. 3. Generally speaking, there are two methods for checking and determining the power chip in the circuit: online determination and determination using electronic components where the integrated circuit (IC) in the circuit is not soldered to the printed circuit board. In this method

02

2022

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11

Integrated Circuit (IC) Manufacturer: What are the characteristics of SMD resistors?

Surface mount resistors, also known as chip resistors, are a type of metal-glass uranium resistor. They are printed onto a substrate using a screen printing method. What are their characteristics? Let's take a look. 1. Small size and light weight, meeting the requirements of product miniaturization; 2. Low temperature coefficient, stable electrical performance, and high reliability; 3. High mechanical strength, stable size, meeting technical requirements; 4. Excellent high-frequency characteristics; 5. Able to withstand wave soldering and reflow soldering, very suitable for technical requirements; 6. Low assembly cost, can be well matched with automatic mounting equipment; 7. Widely used in mobile communications, computers, household appliances, toys, medical devices, LED lights, driver power supplies, etc. Integrated circuit manufacturers believe that resistance is represented by 'r', with the unit being ohms; the greater the resistance of a conductor, the greater the resistance of the conductor to current. Compared with traditional color-coded resistors, surface mount resistors are smaller. When using color-coded resistors, a hole needs to be drilled, while chip resistors do not, occupying less PCB area. Currently, high-end flagship mobile phones use at least hundreds of surface mount resistors. Integrated circuit manufacturers believe that resistors are circuit components that limit current or divide voltage.

25

2022

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10

Some knowledge points about SMD resistors

Common surface mount resistors used in electronic design include thick-film resistors, thin-film resistors, and alloy resistors. They are very similar in appearance, especially thick-film and thin-film resistors, which are almost identical. Thick-film and thin-film resistors generally have the same layered structure; the difference lies in the process of the resistor layer on the ceramic substrate. Thick-film resistors generally use screen printing, while thin-film resistors use vacuum evaporation, magnetron sputtering, etc. The difference in the manufacturing processes results in different precision and electrical characteristics for the two types of surface mount resistors. Common precision levels for thick-film resistors are 1%, 5%, and 10%; they have poor precision, a large temperature coefficient, and are difficult to control. Thick-film resistors are typically used in circuits such as the switching power supply circuits of televisions or power amplifiers in audio systems. In contrast, thin-film resistors have very good precision, such as 0.10% and 0.1%, and a temperature coefficient that can reach 5ppm. Therefore, their resistance values are relatively stable and reliable, and they are often used in power supplies and electrical equipment. Another commonly used alloy resistor has an alloy plate instead of a resistor film in its structure. Because the conductive resistance of the alloy plate is generally small, it has a strong current carrying capacity and stable resistance, so it is generally used for current detection in circuits. Common packages for conventional surface mount resistors (thin-film, thick-film, alloy) are...

13

2022

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10

Some common sense about SMD resistors

Surface mount resistor manufacturers believe that in order to ensure good solderability and reliability, the electrode structure usually has three layers: inner, middle, and outer. The inner layer is the inner electrode (silver-palladium alloy printed sintering) connected to the resistor. The middle nickel-plated layer, also known as the barrier layer, is used to improve the heat resistance of the resistor and buffer the thermal shock during welding (to prevent the inner electrode from being corroded by the solder). The outer tin-lead layer, also known as the solderable layer, is formed by electroplating a tin-lead alloy. Its function is to make the electricity have good solderability and extend the life of the electrode (electroplated tin-lead alloy). Surface mount resistor manufacturers believe that the resistance value of the resistor material used to manufacture surface mount resistors will change with temperature, and the resistance value of the resistor will definitely change with this temperature change. The commonly used unit is 100 PPM/, among which thick-film chip resistors can generally reach 50 PPM/, and higher ones need to use thin-film chip resistors. Surface mount resistor manufacturers believe that a varistor is a voltage limiting protection device. Using the nonlinear characteristics of the varistor, when an overvoltage appears between the two poles of the varistor, the voltage can be clamped to a relatively fixed voltage value, thereby protecting the subsequent circuit. The main parameters of the varistor are: varistor voltage, current capacity, junction capacitance, response time, etc. Surface mount resistor