Core machining

Chip mounting is a crucial process in semiconductor packaging and testing. Its core function is to precisely transfer and mount the prepared chip onto a leadframe, substrate, or carrier plate, laying the foundation for subsequent bonding and encapsulation processes. It directly impacts the yield and performance stability of semiconductor devices and is widely used in the manufacturing processes of microelectronic devices such as integrated circuits, power semiconductors, and sensors.

The core process of chip mounting can be divided into three main steps: chip pickup, alignment and positioning, and mounting and curing. First, the equipment picks up a single chip from the blue film on the wafer using a vacuum nozzle. The pickup process requires precise control of the suction force to avoid damaging the chip's fragile circuit structure due to excessive suction or causing the chip to detach due to insufficient suction. Next comes the alignment stage, the core precision control point of chip mounting. Mainstream technologies employ vision recognition systems, using high-resolution industrial cameras to capture the reference marks between the chip and the substrate. Image algorithms then perform micron-level alignment, ensuring that the chip pins perfectly match the substrate pads, while correcting any angular misalignment of the chip. After alignment, the chip is stably placed on the designated position on the substrate and then fixed by dispensing or thermosetting curing. Dispensing curing requires pre-applying epoxy or conductive adhesive to the corresponding position on the substrate, while thermosetting curing uses a temperature-controlled pressure head to apply specific temperature and pressure, ensuring a reliable bond between the chip and the substrate.

Depending on the requirements of different packaging processes, chip mounting can be categorized into several types. For traditional leadframe packaging, high-speed fully automated mounting is often used to achieve large-volume continuous production. For flip chip packaging, high-precision flip-chip mounting technology is required, with the chip mounted face down, demanding higher alignment accuracy and pressure control. For micro-devices or irregularly shaped chips, semi-automatic mounting machines can be used in conjunction with manual positioning to meet the needs of small-batch, multi-variety production. Furthermore, in power semiconductor packaging, chip mounting must also consider heat dissipation requirements; some processes add heat sinks between the chip and the substrate, requiring the mounting machine to have composite mounting capabilities.

Chip mounting has stringent requirements for the operating environment and process details. Processing must be carried out in a cleanroom with a cleanliness level of Class 100 or higher to prevent airborne particles from adhering to the chip surface and causing short circuits or performance degradation. In terms of process, adhesive dosage control is crucial; too much adhesive can lead to overflow and contamination of chip pins, while too little adhesive will compromise bonding strength. Mounting pressure and temperature must be precisely adjusted according to chip size, material, and adhesive type. Excessive pressure may crush the chip or deform the substrate, while excessive temperature may damage the chemical properties of the adhesive, affecting curing.

Quality control is maintained throughout the entire processing. Common defects include chip misalignment, missing chips, chip adhesion, and chip cracks. Real-time monitoring using online inspection equipment is necessary; any defects detected should trigger an alarm and process parameters should be adjusted accordingly. Simultaneously, the equipment requires regular precision calibration, including nozzle verticality calibration, vision system calibration, and motion platform positioning accuracy testing, to ensure long-term operational stability.

As semiconductor devices evolve towards miniaturization and high integration, on-chip machining technology is also continuously upgrading, exhibiting a trend towards high precision, high speed, and intelligence. The new generation of wafer fabrication equipment integrates artificial intelligence algorithms, enabling automatic defect identification and process parameter self-optimization. It is also compatible with larger wafers and smaller chips, meeting the development needs of advanced packaging technology.