Prony Series Viscoelastic Modeling for Sensor Packaging Stress Relaxation Analysis
Prony series modeling converts polymer relaxation data into actionable sensor zero-drift predictions, isolating packaging strain from true physical signals.
Thermal Bake Conditioning
Moisture Removal
Controlled heating protocols prepare electronic components for high temperature assembly by removing absorbed contaminants and moisture. The process of thermal bake conditioning prevents the occurrence of the popcorn effect, where trapped moisture expands rapidly during solder reflow and damages the package. Components are placed in a dry oven at a specific temperature for a duration determined by their moisture sensitivity level.
Baking is a requirement for many integrated circuits or power modules before they can be safely soldered to a board.
Diffusion Rate
Temperature and humidity levels in the storage area dictate how much water vapor is absorbed by the plastic packaging. During thermal bake conditioning, the elevated temperature increases the kinetic energy of the water molecules, allowing them to diffuse out of the material. A typical cycle might involve 24 hours at 125 degrees Celsius for parts that have exceeded their floor life.
If the temperature is too low, the moisture remains trapped in the core of the package.
Stress Relief
Internal mechanical stresses from the molding process can also be reduced through this thermal exposure. While the primary goal is drying, thermal bake conditioning serves to stabilize the physical dimensions of the component. This reduces the risk of warpage when the part is later exposed to the 260 degree heat of a reflow oven.
Consistent application of this process ensures the reliability of the final assembly.
Process Window
Oven calibration and airflow monitoring ensure that every part in the batch receives uniform heat. The effectiveness of thermal bake conditioning is verified by weighing the samples before and after the cycle to measure the loss of mass. If the parts are not used within a certain time after drying, they must be returned to the oven.
This cycle maintains the integrity of the moisture barrier and prevents assembly defects.