Application of ball mounting technology in the SMT chip processing industry is now essential, and EMS companies must understand wafer-level and chip-level packaging technology to meet the needs of OEM customers. Next, I will introduce the ball mounting technology applied to PCB circuit boards. The process consists of four steps: fluxing, ball placement, inspection, and rework, and reflow.

Fluxing is the first step in ball placement to keep the balls in place and form well in reflow. A specially designed stencil is used for paste flux printing, and the opening of the stencil is determined based on the pad size and solder ball size of the printed circuit board. Two types of squeegees are used, and the ideal parameters for flux printing are determined using the Design of Experiments (DOE). The stencil is easily damaged and needs to be handled carefully. Dust or foreign substances can block the opening of the stencil, and cleaning agents such as isopropyl alcohol cannot be used.

After flux printing, visual inspection is difficult, and an online inspection using AOI equipment is essential after ball placement. Defects are usually missing balls and misalignment. Circuit boards with fewer balls need to be reworked with off-line semi-automatic ball filling equipment, while misalignment defects require cleaning the PCB circuit board and reprinting. The lead-free solder alloy SAC105 is commonly used, and AOI inspection is required after reflow soldering.

The entire process of ball mounting technology applied to PCB circuit boards is critical for achieving high-quality SMT chip processing and production. It requires attention to detail and careful handling to ensure proper flux printing, ball placement, and inspection.