How to detect and distinguish IC chip oxidation? Chip pin oxidation treatment

Date：2022-07-26 15:12:24Views：2470

Pin, also known as pin, is called pin in English. It refers to the wiring from the internal circuit of the integrated circuit (chip) to the peripheral circuit, and all pins constitute the interface of this chip. A section at the end of the lead is soldered together with the pad on the printed board to form a solder joint. Pins can be divided into heel, toe, side and other parts. Then, how to detect and distinguish IC chip oxidation? The following is a brief analysis of chip pin oxidation and treatment for your reference.

Detection and judgment of chip oxidation:

Generally, chip oxidation means that the pins or pads of the chip are oxidized. At this time, according to experience, the following methods are used for detection:

1. Visual identification: the surface of the pin or pad is obviously black or yellow, which cannot be scraped with a blade, and it is the same with washing with washing water;

2. Magnifying glass observation: the surface of pins or pads is black and irregular, and there is no reaction when wiping the surface with plate washing water;

The above two methods can judge most of the oxidation. How to confirm whether it is oxidation? Using ferrochrome or tin furnace, tin the pins directly (pay attention to the temperature in the specification). If the tin consumption of normal pins and pads can be greater than 95%, it is qualified. For some pads, the pins are relatively small, and you must use a magnifying glass to observe.

In addition to the above two methods, next, the method of determining IC pin oxidation is shared with you:

1、 Inspection method:

1. Observation method: whether there is burning, burning, blistering, broken wire 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 board that is clearly broken, slightly increase the voltage by 0.5-1v. After starting up, use the IC on the board by hand to make the chip in question heat up, so as to perceive it.

4. Logic pen check: check whether the signal at the IC input, output and control pole ends is strong or not.

5. Identify the major working areas: most boards have a clear division of labor on the area, 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 an input or an output, then check whether there is a control signal (clock) of the IC. If there is a control signal, the IC is very likely to be broken. If there is no control signal, trace it to its previous pole until the damaged IC is found.

2. If you find one, don't remove it from the pole for the time being. You can choose the same model. Or the IC with the same program content is carried on the back, and start the machine to observe whether it gets better to confirm whether the IC is damaged.

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

4. Comparison method: find a good computer board with the same content and compare 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 damage the board and cannot be recycled.

2. Dragging tin 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 at the same time (easy to damage the board, but 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 will come out (not easy to master).

4. Tin pot method: make a special tin pot on the electric stove. After the tin melts, immerse the IC to be removed from the board into the tin pot, and then the IC can be removed 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, which can take the IC after tin melting out as professional hardware maintenance. Board maintenance is one of the very important items.

IC deoxidization treatment method

That's all for judging the oxidation and treatment methods of IC chip pins. There is no authoritative solution for the oxidation treatment methods of IC chip pins for the time being. The following methods are excerpted from the network:

First of all, we should judge the severity of IC oxidation. As long as the IC pin or tin ball is not blackened, we can use specially prepared potion to remove oxidation. Specific steps: put the oxidized IC into the container containing the special potion, take it out and dry it after 5-10 seconds; If the oxidation is serious, repeat the above steps until the oxide layer is completely removed. However, if the IC pin or tin ball turns black, it cannot be oxidized in the above way. The external pin IC should be electroplated again after the original tin coating is removed, and the BGA should be replanted. I hope the above content can help you.