Alu Alu foil specifications explained: reading a COA before you buy
The numbers on an Alu Alu foil certificate of analysis, what each one means and the limits to look for.
Business Land Trading,
A certificate of analysis (COA) is the quickest way to judge a lot of Alu Alu foil before it reaches your blister machine. Here is what the main lines mean, using a typical 160 micron foil as the example.
Structure and thickness
| Layer | Typical value | Why it matters |
|---|---|---|
| OPA (oriented polyamide) | 25–28 µm | Gives the aluminium the stretch to form without cracking |
| Aluminium | 45–60 µm | The barrier layer; thicker foil allows deeper cavities |
| PVC | 60 µm | The sealing layer that bonds to the lidding foil |
| Total | 140–180 µm (160 µm standard) | Includes adhesive layers between films |
Barrier values
- Water vapour transmission: should be below 0.5 g/m² per 24 hours.
- Oxygen transmission: should be below 0.5 cm³/m² per 24 hours at 0.1 MPa.
- Pin holes: none visible in the light test.
Mechanical values
- Bond (peel) strength OPA/AL: at least 8.0 N/15 mm. Low values risk delamination during forming.
- Bond strength AL/PVC: at least 7.0 N/15 mm.
- Heat seal strength: at least 6.0 N/15 mm against the lidding foil.
Safety and hygiene values
- Vinyl chloride monomer: at most 1 ppm.
- Heavy metals: at most 1 ppm.
- Microbial counts (bacteria, moulds and yeast, E. coli) within the pharmacopoeial limits.
- Reference standard: for Chinese-origin foil this is usually YBB00242002-2015.
Dimensions
Check the width tolerance (typically ±1 mm), core inner diameter (76 mm is standard) and roll weight against your purchase order and machine.
Ask your supplier for the COA with every lot, and keep a retained sample. We share the COA for the Alu Alu foil we supply on request.
