PETG Blister & Hypak Lid Heat Seal Validation: Test Parameters & Results

For medical device manufacturers, a reliable sterile barrier system depends on one critical step: consistent, validated heat sealing between the blister tray and lid material. Even a small mismatch in temperature, pressure or sealing time can lead to seal leakage, sterilization failure and product recalls.

At Honest Packaging, we perform material-specific heat seal validation for every new blister and lid combination before mass production. In this article, we share our complete heat seal test between SK PETG blister trays and Qingyun Kunlun Hypak lids, including equipment, parameters, test procedure and final results.

1. Test Objective & Materials

The objective of this test was to validate the optimal heat seal parameters for sealing SK PETG blister trays with Qingyun Kunlun Hypak lid material, and verify seal consistency, adhesive transfer and edge quality across repeated production cycles.

1.1 Equipment

• Heat sealing machine: Honest Packaging H400 model heat sealer
• Heat sealing mold: H400 custom mold matched to blister flange dimensions

1.2 Test Materials

• Blister trays: Honest Packaging exhibition grade SK PETG blister trays, 50 pieces
• Lid material: Qingyun Kunlun Hypak lids, 50 pieces

Both materials are widely used in medical device sterile packaging due to their excellent biocompatibility, sterilization compatibility and seal performance. Hypak is a popular alternative to Tyvek for applications requiring good gas permeability and consistent peel performance.

2. Heat Seal Test Parameters

After initial parameter scouting, we selected the following optimized heat seal parameters for this material combination. All parameters were kept constant across all 50 test samples to verify consistency.

These parameters are specific to this material combination. Different PETG grades, lid coatings or flange designs may require adjusted parameters. We always recommend performing a dedicated validation for every new material or design change.

3. Test Procedure

1. Equipment calibration: The H400 heat sealer was preheated to 105°C and allowed to stabilize for 15 minutes. Temperature and pressure were verified using calibrated measurement tools.
2. Sample preparation: 50 SK PETG blister trays and 50 Qingyun Kunlun Hypak lids were inspected for defects, dust and deformation. Only intact samples were used for the test.
3. Heat sealing: Each blister was loaded into the H400 mold, covered with a Hypak lid, and sealed at 105°C, 4 bar for 4 seconds. All 50 samples were sealed consecutively without parameter adjustment.
4. Post-seal inspection: Every sealed sample was visually inspected for edge flatness, adhesive transfer, warping and seal defects. Peel tests were performed on random samples to verify seal strength and peel consistency.
5. Data recording: All observations, defects and test results were recorded for batch traceability and regulatory documentation.

4. Test Results & Observations

All 50 samples passed visual inspection. The heat seal results are summarized below:

The test confirms that the parameter set of 105°C, 4 bar, 4 seconds is optimal and reliable for sealing SK PETG blister trays with Qingyun Kunlun Hypak lids. This parameter set has been approved for mass production and included in our process validation documentation.

For medical device brands, this level of material-specific validation is critical to meeting ISO 11607 sterile barrier system requirements and ensuring consistent seal integrity across production batches.

5. Key Takeaways for Medical Device Brands

1. Never use generic seal parameters: Every blister material, lid coating and flange design requires dedicated validation. Parameters that work for Tyvek may not work for Hypak, and vice versa.
2. Validate across multiple samples: A 50-sample test (as performed here) verifies consistency, not just single-sample performance. Always require batch-level validation data from your packaging supplier.
3. Check adhesive transfer, not just visual seal: A visually flat seal can still have weak adhesive transfer. Always perform peel tests to verify complete and uniform adhesive transfer.
4. Require cleanroom production: For Class II and III devices, blister converting and sealing should be performed in a Class 10000 (ISO 7) cleanroom to control bioburden and particle contamination.
5. Keep full validation records: All test parameters, results and observations should be documented and retained for FDA, CE and customer audits.

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