HASS testing (Highly Accelerated Stress Screen) is an accelerated reliability screen that can reveal latent flaws not detected by ESS (Environmental Stress Screening), burn-in, and other test methods. HASS testing uses stresses beyond specification, but within the capability of the design as determined by the HALT. The combination of variable thermal and simultaneous vibration stresses, in conjunction with product specific stresses, finds those defects and marginal products that used to show up as “out of box” instant failures, and increased warranty costs. Because the stresses in HASS are more rigorous than those delivered by traditional approaches, HASS testing substantially accelerates early discovery of manufacturing process issues. Reliability engineers can then correct the variations that would otherwise lead to failures in the field and virtually eliminate shipment of defective products.