Reflow soldering and wave soldering are the two dominant PCB assembly technologies, optimized for SMT (Surface Mount Technology) and THT (Through-Hole Technology) respectively, with distinct application scenarios.

Reflow soldering is designed for SMT components (01005/0201 chips, QFP, BGA, CSP) and high-density, miniaturized products. The process involves applying solder paste to pads via stencil printing, placing components with pick-and-place machines, and heating the PCB in a reflow oven with precise temperature profiles (preheat, soak, reflow, cool) to melt the paste and form reliable joints. It excels at fine-pitch components (≤0.5mm), tiny packages, and heat-sensitive devices, making it ideal for smartphones, wearables, routers, and medical devices with high component density. Reflow soldering delivers high precision (±0.02mm placement), consistent quality (99.2%–99.8% yield), and supports double-sided assembly.

Wave soldering targets THT components (DIP connectors, power transistors, capacitors, and heavy-duty connectors) and mixed-technology boards with through-hole parts. The process involves inserting THT components into PCB holes, fluxing the board, and passing it over a molten solder wave (250–260°C) that wets the holes and component leads, forming strong mechanical and electrical connections. It is cost-effective for high-volume THT assembly, handles large/heavy components, and is widely used in industrial controls, power supplies, automotive electronics, and home appliances with robust through-hole connections. Wave soldering has lower equipment costs than reflow but slightly lower yield (98.5%–99.3%) and is unsuitable for fine-pitch SMT components.