IC chip pin detection: identification, oxidation and function introduction

Date：2021-10-20 13:30:00Views：2828

Whether the IC chip pins are qualified is the key to the detection of the molding separation process. To solve this problem, a detection system for chip detection automation in molding separation process is developed by using machine vision and machine automation technology. The experimental test shows that the equipment has high detection accuracy and speed, and can meet the needs of production. The following mainly introduces the IC chip pin judgment sequence, oxidation and function introduction and detection.

First, let's talk about the method of identifying digital IC pins:

Point the letters and codes on the front of the IC to yourself, and make the positioning mark face to the bottom left, then the pin at the bottom left is the first pin, and then count the pins in turn counterclockwise, that is, the second pin, the third pin, etc. The pin ordering of some imported IC circuits is reverse. Models of these ICs are followed by the suffix letter "R". If there is no "R" after the model, it is a forward type pin, and if there is "R", it is a reverse type pin.

Determine whether the IC pin is oxidized:

1、 Board inspection method:

1. Observation method: whether there is burning, burning, blistering, broken line on the board surface and socket corrosion.

2. Meter measurement method: whether the resistance of + 5V and GND is too small (below 50 ohms).

3. Power on inspection: for the broken board, slightly increase the voltage by 0.5-1v. After startup, rub the IC on the board by hand to make the faulty chip heat up, so as to perceive it.

4. Logic pen check: check whether the signal at each end of IC input, output and control pole is strong or weak.

5. Identify major work areas: most boards have clear division of labor in areas, such as control area (CPU), clock area (crystal oscillator) (frequency division), background picture area, action area (people, aircraft), sound generation and synthesis area, etc. This is very important for the in-depth maintenance of the computer board.

2、 Troubleshooting method:

1. According to the instructions of the manual, first check whether there is a signal (wave type) at the input and output terminals of the suspected chip. If there is any input and no output, then check whether there is a control signal (clock) of the IC. If there is any, the IC is very likely to be broken. If there is no control signal, trace it to its front pole until the damaged IC is found.

2. Do not remove the found from the pole temporarily. The same model can be selected. Or the IC with the same program content is carried on the back. Start up and observe whether it gets better to confirm whether the IC is damaged.

3. Find a short route by tangent and jumper method: if it is found that some signal lines are short circuited with ground wires, + 5V or other pins that should not be connected to multiple ICs, cut off the line and measure again to judge whether it is an IC problem or a wiring problem on the board, or borrow signals from other ICs to weld them to ICs with wrong wave shape to see whether the phenomenon picture is getting better and judge the quality of the IC.

4. Comparison method: find a good computer board with the same content and measure the pin wave pattern and number of the corresponding IC to confirm whether the IC is damaged.

5. IC is tested with ictest software in microcomputer universal programmer (all-03 / 07) (expro-80 / 100, etc.).

3、 Computer chip disassembly method:

1. Foot cutting method: it does not hurt the board and cannot be recycled.

2. Tin dragging method: solder tin on both sides of the IC pin, drag it back and forth with a high-temperature soldering iron, and pull out the IC (vulnerable plate, but it can preserve the test IC).

3. Barbecue method: barbecue on alcohol lamp, gas stove, electric stove, etc. after the tin on the board melts, the IC (not easy to master).

4. Tin pot method: make a special tin pot on the electric furnace. After the tin melts, immerse the IC to be removed from the board into the tin pot to remove the IC without damaging the board, but the equipment is not easy to make.

5. Electric hot air gun: remove the chip with a special electric hot air gun and blow the IC pin to be removed, so that the IC after tin melting can be taken out as professional hardware maintenance. Board maintenance is one of the very important items.

IC chip pin function:

(1) Pin is a multi-function pin. The second audio IF signal under various systems can be demodulated from this pin into the internal FM demodulation circuit in an unbalanced way. At the same time, it is also the control pin for intra block AV \ TV conversion and pal, NTSC and SECAM color system conversion, and the input impedance is about 3.4K.

(2) The pin is the identification output pin, which outputs the image identification signal in the ○ C gate mode. When the TV mode has received the image TV signal, the pin presents a high impedance externally, and the high-level signal can be obtained by external pull-up resistance; When no signal is received, the pin presents low impedance and outputs low level.

Look with a magnifying glass. There are too many pins. It's difficult to measure with a multimeter. If you are really worried, blow it again with a hot-air gun and adjust the temperature. Some chips are not resistant to high temperature, and there is no problem at about 350 degrees. The simplest thing is to power on the test. If it's OK to use it, it's OK.

Measuring with the resistance gear of the multimeter should be to measure whether the chip is damaged. There is resistance between the normal chip pins. You can also measure the voltage value online. By comparing with the general data, you can know the quality or performance of the chip.

The above is the related content of "IC chip pin detection" brought by the core detection. Through this article, I hope it can be helpful to you. If you like this article, you might as well continue to pay attention to our website, and we will bring more wonderful content later. If you have any needs related to the inspection and testing of electronic products, please call Chuangxin testing, and we will serve you wholeheartedly.