How to Choose Aluminum Foil for Medicine Blister Packs

Material Application: pharmaceutical blister foil

Product: 8011 aluminum foil, 8021 aluminum foil

Project Details:

In pharmaceutical blister packaging, aluminum foil for medicine blister packs protects drugs from moisture, oxygen, and light. Choosing the wrong material leads to seal failure, reduced drug efficacy, or even product recalls. This guide covers key selection criteria for pharmaceutical blister foil.

Alloy and Temper: 8011, 8021, or 1235?

Different alloys offer different forming and barrier performance.

- 8011 – High strength, good pinhole control. Best for standard blisters. Most cost-effective.

- 8021 – Higher elongation (≥2.5%). Suitable for deep-drawn or irregularly shaped blisters.

- 1235 – Aluminum purity ≥99.35%, extremely few pinholes. Used for high-value or highly sensitive drugs.

The usual temper is H18 (hard) , providing enough stiffness and proper push-through force. For special deep-drawing needs, O‑temper (annealed) foil is available.

Thickness and Tolerance: 20μm or 25μm?

The most common thicknesses for pharmaceutical blister foil are 20μm and 25μm.  

- 20μm – For standard blisters. Easier push-through.  

- 25μm – For larger blisters or higher mechanical strength.

Thickness tolerance should be within ±5% to ±8% (per GB 12255 or ASTM B479). Excessive tolerance leads to weak sealing or rupture during forming.

Pinhole Count: An Invisible but Critical Defect

Pinholes are microscopic holes through the foil. They destroy barrier properties.

- Industry standard: ≤20–30 pinholes per square meter (depending on drug sensitivity).  

- Test method: Visual counting on a light table or automatic pinhole detector.

For moisture‑sensitive or easily oxidized drugs, request pinhole reports per roll. Choose foil with ≤10 pinholes/m² for the highest protection.

Mechanical Properties: Tensile Strength and Elongation

- Tensile strength – H18 temper requires ≥80 MPa (typical values 95–115 MPa). Lower values cause breakage during forming or transport.  

- Elongation – Must be ≥1.0% , preferably 1.5%–2.5%. Insufficient elongation cracks the foil during stamping, leaving blisters poorly shaped.

Always ask for batch tensile test reports.

Safety and Regulatory Compliance

Pharmaceutical blister foil directly contacts drugs. It must meet one of these standards (based on target market):

- USA: FDA 21 CFR 176.170  

- EU: EU 10/2011  

- China: YBB00152002-2015 (Pharmaceutical aluminum foil standard)

Suppliers must provide compliance declarations for heavy metal migration, overall migration, and sensory tests. Check that the foil surface is free of oil stains, odor, and visible corrosion.

Barrier Performance: WVTR and OTR

High‑quality aluminum foil theoretically has near‑zero water vapor transmission rate (WVTR) and oxygen transmission rate (OTR). However, pinholes increase these values significantly.

- Acceptable upper limits: WVTR < 0.01 g/(m²·24h) , OTR < 0.01 cm³/(m²·24h·atm)  

- If you cannot test WVTR/OTR directly, use pinhole count and thickness as indirect indicators.

Heat Seal Compatibility with Rigid Films

Bare foil cannot be heat‑sealed directly. It requires a heat‑seal lacquer (VC, PVC, or acrylic) applied by a specialized coating company. When selecting bare foil, check:

- Surface wetting tension ≥31 dyne/cm – to ensure good lacquer adhesion.  

- Final heat seal strength typically ≥12 N/15mm (depending on the pharmaceutical standard).

Recommendation: Test the combination of your bare foil and your rigid film (PVC/PVDC/PP) before bulk purchase.

Supplier Quality Control and Test Reports

A good supplier provides per‑roll certificates of analysis including:

- Thickness tolerance  

- Pinhole count  

- Tensile strength / elongation  

- Wetting tension  

- Compliance statements (FDA/EU/YBB)

Prefer suppliers certified to ISO 15378 (GMP for pharmaceutical packaging materials) or ISO 9001.

Quick Selection Checklist

Mingtai Aluminum offers reliable, high-purity aluminum foil for medicine blister packs with strict pinhole control and full compliance test reports – trusted by global blister pack manufacturers.

FAQ

Q1: What is the most common thickness for pharmaceutical blister foil?  

A: 20μm and 25μm are most common. Choice depends on blister depth and desired push‑through force.

Q2: How can I quickly check pinhole quality?  

A: Take an A4 sample and count pinholes on a light table. Acceptable level: fewer than 30 pinholes per square meter.

Q3: Which alloy is better for deep‑draw blisters, 8011 or 8021?  

A: 8021 offers higher elongation, suitable for deep or irregular blisters. 8011 is more cost‑effective for standard blisters.

Q4: What documents should an FDA‑compliant supplier provide?  

A: A migration test report and a compliance statement for 21 CFR 176.170.

Q5: Why does my foil seal sometimes leak air after heat sealing?  

A: Possible causes – too many pinholes or low wetting tension (poor lacquer adhesion). Test pinhole count and surface energy first.