Blister pack is a term for several types of pre-formed plastic packaging used for pharmaceuticals.
The primary component of a blister pack is a cavity or pocket made from a formable web, usually a thermoformed PVC film. This usually has a backing of paperboard or a lidding seal of aluminum foil laminated with a plastic, usually PVC.
Blister packs are useful for protecting the product against external factors such as humidity and contamination for extended periods of time.
Opaque blisters also protect sensitive products against daylight.
The principal advantages of PVC are the low cost and the ease of thermoforming. It also protects against moisture ingress and oxygen ingress. Typical values for the Water Vapor. Transmission Rate (WVTR or MVTR) of a 250µ PVC film are around 3.0 g/m2/day measured at 38 °C/90%RH and the Oxygen Transmission Rate (OTR) is around 20 mL/m2/day.
PVC blisters offer structural rigidity and physical protection for the pharmaceutical dosage form. On the other hand, the blister cavity must remain accessible by the push-through effect and the formed web may not be too hard to collapse when pressed upon; for this reason the PVC sheet thickness is typically chosen of 250 µ.
PTMC delivers both PVC films for the clamshells as well as the lamination films (60 µ)