Blister Lidding Foil

Blister lidding foil is one of the core components of pharmaceutical blister packaging (PTP, Press Through Packaging). Its main function is to be heat-sealed with plastic rigid films (such as PVC, PVDC, etc.) to form independent sealed units, protecting medicines from light, moisture, oxygen, and microbial contamination.

In the pharmaceutical packaging field, blister packaging is one of the most commonly used forms for solid oral dosage forms such as tablets and capsules. As a key component of the blister packaging system, blister lidding foil directly affects the stability and safety of the medication.

We offer a wide range of high-quality blister foils that can be customized to meet your product requirements. With the support of our expert team, we help you accurately select aluminum foil to optimize product protection, usability, and cost-effectiveness.

As a leading manufacturer, HC Aluminum is dedicated to providing comprehensive blister lid solutions for the pharmaceutical market. Our flexible packaging materials strictly meet blister packaging requirements and provide excellent product protection, giving you peace of mind.

Structure and Composition of Blister Lidding Foil

Blister lidding foil is typically a multi-layer composite material with a typical structure including:

Protective Layer (OP Layer)

Located on the outermost layer, usually made of polyester or acrylic coating, it protects printed patterns from abrasion and provides certain chemical resistance.

Printing Layer

Can be printed single-sided or double-sided with pharmaceutical information (such as name, dosage, batch number), using specialized pharmaceutical inks to ensure safety and non-toxicity.

Aluminum Foil Substrate (AL Layer)

The core barrier layer, typically with a thickness of 0.018–0.08 mm. Common alloys include 8011, 8021, and 8079 (in O or H18 temper). The aluminum foil provides high opacity, oxygen barrier (≤0.5 cm³/m²·24h), and moisture resistance (water vapor transmission rate ≤0.5 g/m²·24h).

Adhesive Layer

A heat-sealing coating (such as polyurethane or acrylic adhesive) that ensures strong bonding with plastic rigid films (PVC/PVDC) under 120–180℃, with sealing strength meeting the mechanical peel strength requirements of pharmaceutical packaging.

Types and Selection Criteria of Blister Lidding Foil Materials

Common Blister Lidding Foil Material Types and Properties

Pharmaceutical Aluminum Foil

Pharmaceutical aluminum foil is the most commonly used lidding foil material in pharmaceutical blister packaging. Both sides are coated with ink, protective layer, and adhesive layer. Based on alloy composition and processing technology, pharmaceutical aluminum foil is mainly divided into the following types:

8011 Aluminum Foil

Mainly composed of aluminum, silicon, and iron. It has good formability and heat-sealing performance. It is the most commonly used material for pharmaceutical aluminum foil, usually with a thickness of 0.016–0.04 mm. 8011-H18 aluminum foil has higher hardness, suitable for blister packaging that requires higher stiffness.

8021 Aluminum Foil

Contains a higher content of iron, providing better barrier properties and mechanical strength. Thickness usually ranges from 0.04–0.065 mm. It is mainly used for high-end and tightly sealed pharmaceutical packaging.

8079 Aluminum Foil

Contains a specific combination of alloy elements, offering excellent corrosion resistance and thermal stability, suitable for special pharmaceutical packaging needs.

Main characteristics of pharmaceutical aluminum foil include:

• Excellent light-blocking performance, completely blocks light
• Highly dense metal crystal structure provides complete barrier to gases and water vapor
• Good heat-sealing performance, can form reliable seals with PVC, PVDC, and other rigid films
• Certain flexibility and mechanical strength to withstand stress during packaging and use

Pharmaceutical Composite Aluminum Foil

Pharmaceutical composite aluminum foil is a functional lidding material developed based on pharmaceutical aluminum foil. It is mainly used for child-resistant packaging, corrosion-resistant packaging, and other special pharmaceutical applications. Some typical composite structures include:

Main characteristics of pharmaceutical composite aluminum foil include:

• Achieves enhanced functionality such as child-resistance and corrosion resistance through lamination processes
• Composite structure and performance can be customized based on specific pharmaceutical needs
• Some composite structures offer easy-to-open features, enhancing patient usability

BOPA Composite Film Materials

In recent years, functional BOPA (biaxially oriented polyamide) films have seen increased application in pharmaceutical blister packaging, especially when laminated with aluminum-based materials. BOPA films have the following characteristics:

Excellent physical properties: high puncture resistance, high tensile strength, and good flexibility. Superior barrier properties: good resistance to oxygen, water vapor, and odors. Good heat-sealing properties: can form reliable seals with a variety of materials. Aesthetic appeal: smooth surface and excellent printability.

Blister Lidding Foil Material Selection Criteria

Pharmaceutical Characteristics and Packaging Requirements

The physical and chemical properties of the drug are the primary considerations when selecting blister lidding foil materials:

• Barrier performance requirements: select lidding foil based on the drug’s sensitivity to moisture, oxygen, and light.
• Physical form: the shape, hardness, and brittleness of the drug affect the choice of lidding material.
• Chemical properties: the acidity, alkalinity, and chemical stability of the drug influence material selection.
• Usage method: consider the administration method and patient demographics.

Compatibility with Packaging Process and Equipment

The selection of blister lidding foil materials also needs to consider compatibility with packaging processes and equipment:

• Heat-sealing requirements: different materials require different temperatures, pressures, and dwell times for heat-sealing.
• Forming performance requirements: for cold-formed blister packaging, the lidding material must have good forming properties.
• Printing performance requirements: if printing is required on the lidding foil, the material must have good ink adhesion and print adaptability.

Material Cost and Supply Chain Management

While meeting pharmaceutical packaging requirements, material cost and supply chain management are also important considerations:

• Material cost: the price of different materials varies significantly; a balance must be found between performance and cost.
• Supplier selection: choose suppliers with good reputation and stable production capacity.
• Inventory management: consider storage conditions and shelf life of materials to plan inventory reasonably.

HC Aluminum Blister Lidding Foil Quality Control

Raw Material Quality Control for Blister Lidding Foil

Aluminum Foil Substrate Quality Control

Aluminum foil substrate is the fundamental material for blister lidding foil, and its quality directly affects the performance of the final product:

Coating Material Quality Control

The coating materials of blister lidding foil include the protective layer, adhesive layer, and printing ink, all of which require stringent quality control:

• Coating Material Selection: Materials should meet pharmaceutical standards and possess good thermal stability, chemical stability, and biocompatibility.
• Coating Thickness Control: Coating weight of protective and adhesive layers must be accurately controlled, and coating variation must meet standard requirements.
• Coating Uniformity Control: Coatings must be uniform, without defects such as missed coating, sagging, or bubbling.
• Solvent Residue Control: For solvent-based coatings, residual solvent levels must be strictly controlled to avoid affecting drug quality.

Blister Lidding Foil Production Process Quality Control

Coating Process Control

Coating is a key process in blister lidding foil production and directly affects the foil's performance:

Coating Parameter Control: Coating speed, coating weight, drying temperature, and time must be precisely controlled.

Coating Equipment Maintenance: Coating equipment must be regularly maintained and calibrated to ensure uniformity and stability of the coating.

Environmental Control: The temperature, humidity, and cleanliness of the coating workshop must be maintained within appropriate ranges.

Printing Process Control

Printing is an important part of blister lidding foil production, impacting the product’s labeling and appearance:

Ink Selection: Use inks that meet pharmaceutical standards, with good adhesion, abrasion resistance, and chemical resistance.

Printing Parameter Control: Printing pressure, ink viscosity, drying temperature, and drying time must be accurately controlled.

Registration Accuracy Control: In multi-color printing, register accuracy must be ensured for clear and accurate patterns and text.

Finished Product Quality Control of Blister Lidding Foil

Appearance Quality Control

Appearance directly reflects the quality of blister lidding foil and must be strictly controlled:

Surface Quality Inspection: The surface of the foil must be clean, flat, and free of visible scratches, indentations, bubbles, oil stains, and other defects.

Edge Cutting Quality Inspection: The edges should be neat and free of burrs, scalloping, curling, unevenness, etc.

Printing Quality Inspection: Printed patterns and text must be clear, complete, accurately registered, and color must meet design requirements.

Pinholes Inspection: Pharmaceutical aluminum foil must not have pinholes larger than 0.3 mm. For pinholes between 0.1–0.3 mm, no more than 1 per m² is allowed. Clustered, continuous, or periodic pinholes are strictly prohibited.

Physical Property Control

Physical properties are core indicators of lidding foil quality and directly affect the safety and effectiveness of drug packaging:

Thickness Measurement: Use a micrometer or thickness gauge to measure foil thickness, which must meet specified ranges and tolerances.

Heat Seal Strength Test: According to Pharmacopoeia standard 4055, the heat seal strength should be ≥7.0 N/15mm (PVC) or ≥6.0 N/15mm (PVDC).

Burst Strength Test: Use a burst tester to determine the foil's bursting strength, which should be ≥98 kPa.

Heat Resistance of Protective Layer: Heat seal the foil at 200℃ and 0.2 MPa pressure for 1 second and check whether the protective layer detaches.

Chemical Property Control

Chemical properties are crucial for the safety of blister lidding foil:

Residual Solvent Detection: Use gas chromatography to detect solvent residue in the foil, which must meet the specified limits.

Heavy Metal Content Detection: Detect heavy metals in aluminum foil, such as lead, cadmium, and mercury, to ensure compliance with pharmaceutical packaging standards.

Fluorescent Substance Detection: Examine the adhesive and protective layers of the foil under 254 nm and 365 nm light for sheet-like fluorescence.

Migration Test: Detect extractables and migrants from the foil material to ensure no adverse effects on the drug quality.

Technical Parameters of Blister Lidding Foil

Barrier Performance Parameters

Oxygen Transmission Rate

The oxygen transmission rate is a critical indicator of a foil's oxygen barrier capacity and directly affects the stability of oxidation-sensitive drugs:

Requirement: Standard pharmaceutical aluminum foil OTR is usually controlled below 0.5 cm³/m²·24h·atm, while high-performance foil can reach below 0.05 cm³/m²·24h·atm.

Water Vapor Transmission Rate

WVTR is an important indicator of moisture barrier performance and is especially important for hygroscopic drugs:

Requirement: Standard pharmaceutical aluminum foil WVTR is usually below 0.3 g/m²·24h, while high-performance foil can reach below 0.01 g/m²·24h.

Mechanical Performance Parameters

Burst Strength

Burst strength refers to the maximum pressure at which foil ruptures under hydraulic pressure, indicating resistance to breakage:

Requirement: Burst strength of pharmaceutical aluminum foil should be no less than 98 kPa.

Heat Seal Strength

Heat seal strength refers to the bonding strength after sealing with rigid blister films and directly affects packaging integrity:

Requirement: Seal strength between pharmaceutical foil and PVC film should be ≥7.0 N/15mm; for PVDC film, it should be ≥6.0 N/15mm.

Processing Performance Parameters

Heat Sealability

Heat sealability refers to the foil’s ability to form a sealed connection with rigid blister film through heat sealing, a key feature for blister packaging:

Requirement: Typical sealing temperature range is 140–170℃, pressure 0.1–0.3 MPa, time 0.5–2 seconds.

Formability

Formability refers to the foil’s ability to deform during blister forming, which directly affects blister shape and dimensional accuracy:

Requirement: Minimum forming radius is typically no less than 0.5 mm; maximum forming depth depends on blister design.

Chemical Performance Parameters

Solvent Residue

Solvent residue refers to the remaining organic solvents in foil from the production process, which may affect drug quality:

Requirement: Total solvent residue should not exceed 5.0 mg/m²; benzene solvent residue should not exceed 0.01 mg/m².

Heavy Metal Content

Heavy metal content refers to toxic elements such as lead, cadmium, and mercury in the foil, which must be strictly controlled:

Requirement: Lead (Pb) ≤10 mg/kg, Cadmium (Cd) ≤1 mg/kg, Mercury (Hg) ≤1 mg/kg.

Applications of Blister Lidding Foil in Different Pharmaceutical Scenarios

Blister Packaging for Regular Tablets

Regular tablets are the most common drug form, with relatively general requirements for lidding foil:

Material Selection: Preferably 8011 aluminum foil, thickness usually 0.02–0.025 mm, in H18 or O temper.

Key Parameters: Oxygen transmission rate ≤0.5 cm³/m²·24h·atm; water vapor transmission rate ≤0.3 g/m²·24h.

Blister Packaging for Capsules

Capsules differ from tablets, especially in terms of opening force and puncture resistance:

Material Selection: Preferably 8011 aluminum foil, thickness usually 0.02–0.025 mm, in H18 temper.

Key Parameters: Puncture force should be controlled within 2.0–3.5 N; opening force should be below 8 N.

Blister Packaging for Effervescent Tablets

Effervescent tablets contain disintegrating agents and require higher sealing and barrier properties:

Material Selection: Preferably 8021 aluminum foil or BOPA/AL composite film, thickness usually 0.025–0.03 mm.

Key Parameters: Oxygen transmission rate ≤0.3 cm³/m²·24h·atm; water vapor transmission rate ≤0.1 g/m²·24h.

Pharmaceutical Packaging for Tropical Regions

High temperature and humidity in tropical regions impose higher requirements on drug packaging:

Material Selection: Preferably 8021 or 8079 aluminum foil, thickness usually 0.03–0.04 mm.

Key Parameters: Oxygen transmission rate ≤0.2 cm³/m²·24h·atm; water vapor transmission rate ≤0.05 g/m²·24h.