Thermal Dehumidification
Thermal treatments conducted at or above one hundred degrees Celsius remove deeply absorbed moisture from electronic components prior to high-temperature assembly. In printed circuit board assembly, a high temperature bake is a remedial process used to restore the floor life of moisture-sensitive devices that have exceeded their allowable exposure limits. This treatment relies on elevated heat to drive out water vapor trapped within plastic packages.
Moisture Evaporation
The baking cycle typically runs at one hundred and twenty-five degrees Celsius for durations ranging from several hours to twenty-four hours, depending on component thickness. This intense heat increases the diffusion rate of moisture through the plastic packaging, allowing it to escape into the oven atmosphere. This process is necessary to prevent delamination or internal cracking during the rapid heating of reflow soldering.
However, these temperatures can accelerate the formation of intermetallic compounds on component leads, which reduces solderability.
Component Stress
Carrier trays and tape-and-reel packaging must be rated to withstand these high temperatures to prevent melting or warping in the oven. Non-bakeable packaging requires components to be transferred to metal or high-temperature plastic trays before processing, which introduces handling risks such as electrostatic discharge or lead damage. Production planners must choose between these thermal bake cycles or low-temperature, low-humidity storage depending on production schedules.
