Blister packaging · Industry glossary
Pinhole
A small, localised hole in packaging material, such as a blister forming web or lidding material.
Also called: blister pinhole; foil pinhole.
Does a pinhole in foil mean the whole blister leaks?
Not automatically. A local hole in the aluminium layer and a hole through the entire laminate are different defects. Identify the material construction and the layer or layers affected before interpreting a finding.
A hole confined to the aluminium layer may leave other plies intact. Its effect on the finished pack depends on the complete structure; the defect name alone does not quantify moisture or oxygen transfer.
Can visual inspection establish a through-hole?
A visible light spot is an optical observation, not a complete description of a leak path. Coatings and other plies can affect visibility, so optical appearance alone may not distinguish a foil-layer hole from a through-hole in the complete structure.
Record the observed location and material layer separately from any demonstrated package leakage. Also distinguish an unintended material hole from the intentional perforation used to separate blister units.
Interpreting a pinhole detection limit
A detection claim needs the specimen and defect type as well as a size. A capability established for a hole in a flat sheet or a channel at an edge seal is not automatically a result for a formed, sealed blister. Package construction and test conditions belong with the claim.
For a supplier comparison, identify whether the example is loose foil, laminate or a finished pack; whether the defect penetrates the full structure; its location; and the method and conditions used. A positive package leak screen may still need separate localisation before the defect can be called a pinhole.
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