How to detect whether there is a problem with domestic IC chips? A few simple moves to understand

Date：2021-07-16 14:19:32Views：1516

We should know that chip testing is mainly to find out the factors affecting product quality in the production process as soon as possible and prevent the occurrence of batch out of tolerance, repair and scrap of chips. It is an important method for product process quality control. Whether domestic chips or foreign chips, there are many detection methods, and the detection aspects are also different. Chip testing is mainly divided into two types: laboratory testing and mass production testing. As we know from the name, laboratory testing is generally a sample test conducted by the application engineer in the company's laboratory to evaluate the chip performance. Mass production testing is a mass production test conducted in the factory to ensure the quality of each chip shipped to customers.

1. Before testing domestic chips, we should understand the working principle of integrated circuits and related circuits

Before checking and repairing an integrated circuit, you should be familiar with the functions, internal circuits, main electrical parameters, the functions of each pin, the normal voltage of the pin, the waveform and the working principle of the circuit composed of peripheral components.

2. Test to avoid short circuit between pins

When measuring voltage or testing waveform with oscilloscope probe, avoid short circuit between pins, and measure on the peripheral printed circuit directly connected with pins. Any instantaneous short circuit is easy to damage the integrated circuit, especially when testing CMOS integrated circuits in flat package.

3. It is strictly prohibited to use grounded test equipment to contact live TV, audio, video and other equipment on the base plate without isolation transformer

It is forbidden to directly test TV, audio, video and other equipment without power isolation transformer with instruments and equipment with grounded shell. Although general tape recorders have power transformers, when contacting special TV or audio equipment with large output power or little understanding of the nature of the power supply used, first make sure whether the chassis of the recorder is charged, otherwise it is very easy to cause power short circuit with TV, audio and other equipment charged on the bottom plate, affect the integrated circuit, and further expand the fault.

4. Pay attention to the insulation performance of electric soldering iron

It is not allowed to use soldering iron for welding with electricity. It is necessary to confirm that the soldering iron is not charged, ground the shell of the soldering iron, and be more careful with MOS circuit. It is safer to use 6 ~ 8V low-voltage soldering iron.

5. Welding quality shall be guaranteed

During welding, it is indeed firmly welded, and the accumulation of solder and air holes are easy to cause false welding. Generally, the welding time shall not exceed 3 seconds, and the power of the soldering iron shall be about 25W. Carefully check the welded integrated circuit, measure whether there is a short circuit between each pin with an ohmmeter, confirm that there is no solder adhesion, and then turn on the power supply.

6. Don't judge the damage of integrated circuit easily

Do not easily judge that the integrated circuit is damaged. Because the vast majority of integrated circuits are directly coupled, once a circuit is abnormal, it may lead to multiple voltage changes, and these changes are not necessarily caused by the damage of the integrated circuit. In addition, in some cases, when the measured voltage of each pin is consistent or close to the normal value, it does not necessarily mean that the integrated circuit is good. Because some soft faults will not cause changes in DC voltage.

7. The internal resistance of the test instrument shall be large

When measuring the DC voltage of integrated circuit pins, a multimeter with an internal resistance greater than 20K Ω / V should be selected, otherwise there will be large measurement error for some pin voltages.

8. Pay attention to the heat dissipation of power integrated circuits

The power integrated circuit shall have good heat dissipation, and it is not allowed to work at high power without radiator.

9. Lead wires should be reasonable

If it is necessary to add peripheral components to replace the damaged parts inside the integrated circuit, small components shall be selected, and the wiring shall be reasonable to avoid unnecessary parasitic coupling, especially the grounding terminal between the audio power amplifier integrated circuit and the preamplifier circuit.

The factories in the chip industry are much cleaner, more modern, more technologically advanced and more in line with the times than those in the traditional industry. With the increasing cost of technological upgrading and the increasing requirements for the production efficiency of IC industry, the whole industry is gradually developing towards the vertical division of labor mode.Chip detection service provides sufficient guarantee for chip detection in the production process of electronic products, and plays an important role.