Environmental Load
Environmental load applied to an integrated circuit package to evaluate its durability under extreme temperature changes. Testing for package thermal stress involves rapid cycling between high and low temperatures to induce mechanical tension between the silicon die and the surrounding plastic or ceramic. This process reveals weaknesses in the internal wire bonds or the interface between the chip and the substrate.
It is a standard part of the reliability qualification for new components used in automotive or industrial environments.
Failure Mode
Stress identification focuses on the cracks that form due to the different rates of expansion among the materials. Because the silicon die expands less than the plastic molding compound, the internal stresses can shear the delicate electrical connections. If a package is poorly designed, moisture can enter through these microcracks and lead to corrosion or a catastrophic explosion during the soldering process.
Engineers use the data from these tests to choose better molding compounds or to redesign the lead frame for better stress distribution.
Reliability Benchmarking
Certification requires hundreds of these cycles to be completed before a part is approved. This ensures that the device will survive the entire expected lifespan of the final product.
