Chip-level repair is a advanced PCBA repair technique that involves repairing or replacing individual chips (integrated circuits) on the PCB, requiring high precision, technical expertise, and specialized tools. One of the key skills for chip-level repair is the ability to identify chip defects accurately, which often requires a combination of visual inspection, electrical testing, and waveform analysis. Visual inspection involves checking for signs of damage such as burnt marks, cracked packaging, or bent pins on the chip. Electrical testing using a multimeter or oscilloscope can help identify issues such as open circuits in the chip pins, short circuits between pins, or abnormal voltage readings, which indicate a faulty chip. Additionally, comparing the waveform of the faulty chip with a known good chip can help pinpoint specific functional defects.

Another critical skill is the proper removal and replacement of chips, especially BGA and QFP (Quad Flat Package) chips, which have multiple pins and require precise heat control. For BGA chips, which have solder balls under the package, a hot air rework station with a specialized nozzle is used to heat the chip evenly. The temperature and air flow must be carefully adjusted to avoid overheating the PCB or damaging adjacent components; typically, the temperature is set between 250°C and 300°C, depending on the chip type and PCB material. Once the solder melts, the chip is gently lifted using a vacuum pickup tool to avoid damaging the solder pads. After removing the chip, the remaining solder balls on the PCB are cleaned using a soldering iron and desoldering braid, and new solder balls are applied to the chip (if necessary) using a stencil and solder paste.

When reinstalling the chip, proper alignment is essential to ensure that all solder balls or pins make contact with the corresponding pads on the PCB. For BGA chips, a alignment tool or visual alignment under a microscope can help ensure accurate positioning. The chip is then reflowed using the hot air rework station, with the same temperature settings as during removal, to create a secure solder connection. After soldering, a visual inspection under a microscope is conducted to check for solder bridges, cold joints, or missing solder balls. Electrical testing is then performed to verify that the chip is functioning correctly, including checking the chip’s power supply, input/output signals, and overall functionality. Additionally, chip-level repair requires knowledge of chip datasheets, which provide information about the chip’s pinout, voltage requirements, and functional specifications, helping technicians identify the correct pins and troubleshoot issues effectively. Mastering these skills requires practice and experience, as well as a thorough understanding of electronic components and PCB design.