Three-Step Precision Troubleshooting for Weak Seals Between Medical Breathable Paper and Thermoformed Packaging

In the medical field, sterility is the lifeline of safety. Serving as the "protective garment" for medical devices, packaging systems composed of medical breathable paper (like DuPont™ Tyvek®) and thermoformed blisters have become the mainstream choice, prized for their clean appearance, excellent microbial barrier properties, and ease of device access. The core of this packaging system lies in the "seal." A loaded blister is hermetically heat-sealed to a breathable paper lid stock using a medical sealing machine, creating a reliable sterile barrier. A weak seal is akin to a dam breach—it nullifies all bacterial barrier functions and is absolutely unacceptable in medical device packaging. So, how do you systematically troubleshoot weak seals between breathable paper and blister packaging? This article categorizes the root causes into three key factors to help you pinpoint and resolve issues quickly.

Root Cause 1: Material Factors – The Foundation Lies in "Heat Seal Compatibility"

Core Question: Is the raw material of the blister cup qualified with proper heat seal performance?

Material selection is the cornerstone of a successful seal in the medical thermoformed packaging industry. PETG material is the acknowledged industry benchmark because it inherently possesses excellent heat seal characteristics, allowing it to form strong bonds with breathable paper. Secondly, some specially modified PET materials can also meet the requirements. However, during troubleshooting, it is crucial to be highly alert to the potential misuse of standard, unmodified PET material. Standard PET has inherently poor heat seal performance; even under otherwise perfect conditions, it is highly likely to result in insufficient seal strength and sealing failure.

Root Cause 2: Tooling Factors – The Problem Lies in "Pressure Transmission"

Core Question: Is the surface of the heat seal die perfectly flat and undamaged?

The heat seal die is the "executor" of the sealing task. It directly contacts the breathable paper, responsible for transferring heat and pressure. If this "executor" itself is flawed, the seal quality will inevitably suffer.

Root Cause 3: Process Factors – The Key is in "Parameter Settings"

Core Question: Are the time, temperature, and pressure parameters on the heat sealer optimized?

A perfect seal is the result of the precise collaboration of three parameters: time, temperature, and pressure. This is a dynamic balancing act—there is no universal "one-size-fits-all" setting.