Packaging seals must balance opposing requirements - adequate strength maintaining integrity through distribution and handling, yet easy opening for clinicians avoiding instruments that could damage products or injure users. Seal peel testing on paper/plastic packages following EN 868-5 Annex E quantifies seal strength ensuring adequate closure without excessive opening force through tensile testing at specified angles. This testing measures both seal strength demonstrating packaging maintains integrity and failure mode revealing whether seals separate properly at paper-plastic interface rather than tearing materials. Essential for validating sealing parameters including temperature, pressure, and dwell time achieving target seal strength, demonstrating consistent seal quality across manufacturing lots, and ensuring packages maintain integrity while remaining openable without excessive force or instruments. For sterile medical device packaging, seal strength directly impacts product safety where weak seals compromise sterility yet excessive strength damages products during opening or causes packages opening incorrectly through material tearing. The testing evaluates seal strength across package perimeter identifying weak areas requiring process attention, validates that corner seals achieve adequate strength despite challenging geometry, and demonstrates storage doesn't degrade seal strength through adhesive aging. Manufacturing validation establishes seal parameter windows producing acceptable strength ranges, process monitoring confirms ongoing seal quality maintenance, and investigation protocols identify root causes when seal strength falls outside specifications. The failure mode assessment proves critical revealing whether materials separate at seal interface as designed or fail through material tearing indicating formulation or process problems requiring correction.