SMT Processing Workshop Specifications for Temperature and Humidity Control
Controlling the environment in the factory is a key measure to prevent defects on printed Circuit Boards (PCBs). Incorrectly managing humidity and temperature can damage expensive electronic components and lead to costly quality problems. Many factors affect the production environment, such as the location of the factory and the equipment used to manufacture the boards. Manufacturers must monitor and adjust temperature and relative humidities in the workshop, even in mild climates around the world.
Relative Humidity
Humidity in a room is determined by the "relative humidty" (Rh), which reflects a ratio between the partial water vapor pressure and the saturated water vapour pressure at the same temperature. Relative humidity is the quantitative measurement of the amount water vapor present in the air.
High Humidity
High humidity can lead to serious problems in manufacturing environments.
Slippage: The welding paste absorbs excessive water, causing it to bridging when reflowing.
welding balls (or "popcorn"): Poor coalescence is caused by excessive water absorption of the welding paste.
Outgassing: When large amounts of water are sprayed on the surface (especially BGAs), they can increase pressure. This can sometimes cause the lid of the device to come off.
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