Driver Weeks Priced into a Sensor Module Decision
Sourcing sensor modules eliminates 4 to 12 weeks of driver engineering, flipping break-even economics below 15,000 units despite higher unit BOM prices.
Reflow Solder Stress
Thermal Loading
Thermal processing during board assembly subjects electronic components to intense heat and rapid cooling cycles. The reflow solder stress refers to the mechanical strain induced in a component when the surrounding materials expand at different rates. This stress can lead to package cracking or shifts in the electrical output of a sensor.
It is a major factor in the stability of precision instruments.
Material Expansion
Silicon, plastic, and copper all have different coefficients of thermal expansion. As the temperature rises to 250 degrees Celsius, these parts pull against each other. The internal die of a sensor is particularly vulnerable to these forces.
If the stress is not relieved, it causes a permanent shift in the zero point of the device.
Internal Strain
Microscopic bonds within the semiconductor can be damaged by the high temperatures. Moisture trapped inside the package might expand and cause delamination. This phenomenon is often called the popcorn effect.
Proper storage in dry bags before assembly prevents this type of failure.
Lifetime Reliability
Repeated thermal cycles during normal operation can worsen the initial assembly damage. Long term drift is often a direct consequence of the strain left behind by the soldering process.