To implement and control the production of surface-mount assemblies, determine the dynamics of the solder reflow process. Each element of the process affects the end result.
The primary phases of the reflow process are listed:
- Melting the particles in the solder paste
- Wetting the surfaces to be joined
- Solidifying the solder into a strong metallurgical bond
The peak reflow temperature of a surface-mount component body must not be more than 250°C maximum (260°C for dry rework only) for Pb-free packages and 220°C for eutectic-SnPb packages, and is package size dependent. For multiple BGAs in a single board and because of surrounding component differences, AMD recommends checking all BGA sites for varying temperatures.
The infrared reflow (IR) process depends on equipment and loading. Lack of thermal constraints can cause components to overheat. Unbalanced loading potentially leads to significant temperature variation on the board.
These guidelines help you avoid component damage and determine the actual profile for your process. Consult the Joint IPC/JEDEC Standard J-STD-020C for package moisture/reflow classification and reflow conditions.