Blister Packing

By CELIA XIE | Updated: 2024-07-18

Medical blister trays differ from pharmaceutical blister packs in that these are not push-through packs. The thermoformed base web is made of a thicker plastic sheet, generally between 500 and 1000 μg and can not be collapsed, thus forming a solid tray. The lidding film provides a peel-open feature and is generally porous to allow sterilization (such as the Dupont medical Tyvek material). Such medical blister packs are basically used for sterile medical consumables, used in hospitals.

In the case of #thermoforming, a plastic film or sheet is unwound from the reel and guided though a pre-heating station on the blister line which will cause the plastic to soften and become pliable. The warm plastic will then arrive in a forming station where a large pressure (4 to 8 bar) will form the blister cavity into a negative mold. The mold is cooled such that the plastic becomes rigid again and maintains its shape when removed from the mold. In case of difficult shapes, the warm film will be physically pushed down partially into the cavity by a "plug-assist" feature. Plug-assist results in a blister cavity with more uniform wall distribution, and is typically used when the cavity size and shape is larger than a small tablets and cables.