Main steps and contents of IC chip fault detection and failure analysis

Date：2022-06-07 17:07:51Views：1416

Generally speaking, the failure of integrated circuits is inevitable in the process of development, production and use. With the continuous improvement of people's requirements for product quality and reliability, failure analysis is becoming more and more important. Chip failure analysis can help integrated circuit designers find design defects, mismatching of process parameters or improper design and operation. How to accurately judge the quality of the power IC chip in the circuit is an important work for the maintenance of TV, audio and video equipment. If the judgment is not accurate, it will not only cost a lot of energy, but also the key is that the integrated circuit fault still exists. Therefore, to correctly judge the integrated circuit is a compulsory course for every maintenance personnel.

1、 Inspection method:

1. observation method: whether it is burnt, burnt out, bubbling, broken wire on the board surface, and rusted socket.

2. meter measurement method: +5v, whether GND resistance is too small (less than 50 ohms).

3. power on inspection: for a clear broken board, slightly adjust the voltage of 0.5-1v. After startup, use the IC on the washboard by hand to make the chip in question heat up, so as to sense.

4. logic pen check: check whether the signal is strong or weak at the input, output and control poles of the key suspected IC.

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

2、 Troubleshooting method:

1. suspect the chip. According to the instructions in the manual, first check whether there is a signal (waveform) at the input and output terminals, and then check the IC control signal (clock), etc. if the IC is broken and there is no control signal, track its front pole until the damaged IC is found.

2. do not remove the same model from the extreme for the time being. Or, put the IC with the same program content on it and start the machine to observe whether it gets better to confirm whether the IC is damaged.

3. find the short circuit through tangent and jumper: if some signal wires and ground wires are found, +5v or other ICS should not be short circuited, cut off the circuit for measurement, judge whether it is the IC problem or the board line problem, or borrow signals from other ICs to weld to the waveform error IC to see if the phenomenon picture is better, and judge the quality of the IC.

4. comparison method: find a good computer board with the same content, measure the pin wave type and quantity of the corresponding IC, and confirm whether the IC is damaged.

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

3、 Chip disassembly method:

1. foot cutting method: it does not damage the board and cannot be reused.

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 start the IC (vulnerable board, but the test IC can be saved).

3. barbecue method: barbecue on alcohol lamp, gas stove and electric stove, and start IC after the tin on the board is dissolved (difficult to master).

4. tin pot method: make a special tin pot on the electric stove. After the tin is dissolved, immerse the IC to be removed from the board into the tin pot to start the IC without damaging the board, but the equipment is not easy to manufacture.

5. electric hot air gun: use a special electric hot air gun to remove the chip, and blow the IC pin to be removed to start the IC after tin melting (pay attention to shake the air gun when blowing the board, otherwise the computer board will bubble, but the air gun cost is high)

IC IC failure is inevitable in the process of development, production and use. The main steps and contents of failure analysis are as follows:

IC unsealing: remove the IC sealant, keep the chip function intact, and keep die, bond pads, bond wires and even lead frame from damage, so as to prepare for the next chip failure analysis experiment.

SEM scanning electron microscope /edx composition analysis: including material structure analysis / defect observation, conventional micro area analysis of element composition, accurate measurement of component size, etc.

Probe test: quickly and conveniently obtain IC internal electrical signal with micro probe. Laser cutting: cutting a circuit or a specific area on the upper layer of a chip with a micro laser beam.

Emmi detection: Emmi low light level microscope is a highly efficient failure analysis tool, which provides a highly sensitive and non-destructive fault location method. It can detect and locate very weak luminescence (visible light and near-infrared light), so as to capture the visible light of leakage current generated by various component defects or abnormalities.

OBIRCH application (laser beam induced impedance value change test): OBIRCH is commonly used for internal high impedance and low impedance analysis, and line leakage path analysis. Using OBIRCH method, defects in circuits can be located effectively, such as holes in lines and holes under through holes. The high resistance area at the bottom of the through hole can also effectively detect short circuit or leakage, which is a powerful supplement to the luminescent microscopy technology.

LG liquid crystal hot spot detection: the liquid crystal is used to sense the arrangement and reorganization of molecules at the IC leakage, showing a mottled image different from other areas under the microscope, so as to find the leakage area (more than 10mA fault point) that puzzles the designer in the actual analysis.

Fixed point / non fixed point chip grinding: remove the gold bumps planted on the LCD driver chip pad and keep the pad intact for subsequent analysis or rebinding.

X-ray nondestructive detection: detect the integrity of various defects in IC packaging, such as layer peeling, burst, hole and wiring, possible defects in PCB manufacturing process, such as poor alignment or bridging, open circuit, short circuit or abnormal connection, and the integrity of tin balls in packaging.

Sam (SAT) ultrasonic flaw detection can carry out non-destructive detection on the internal structure of IC packaging, and effectively detect various damages caused by moisture or heat, such as: 1. Delamination of the wafer surface 2. Cracks in the tin ball, the wafer or the glue filling 3. Air holes in the packaging material 4. Various holes, such as holes at the junction of the wafer, the tin ball, the glue filling, etc.

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