Guide to achieving good adhesion
Introduction
Achieving a "good bond" is less about the glue itself and more about the science of the interface. Regardless of the material you are working with, the strength of the joint usually fails because of surface prep, not the chemical adhesive.
When the materials to be bonded are not compatible with adhesives, especially applicable when bonding to high performance engineering materials with low surface energies such as PP, PE or PTFE additional surface preparation will be required beyond cleaning.
Bonding PTFE and PP
Diagnostic Approach: Why Bonds Fail
Before selecting a process, we identify the specific barrier to your adhesion. Most failures fall into three categories:
- Molecular Contamination:Invisible films of lubricants, fingerprints, or release agents that prevent direct contact.
- Mechanical contamination:Fine dust from traditional abrasive roughening that creates a "false" surface.
- Inherent Surface Energy:Smooth, "chemically lazy" surfaces (like PTFE) that lack the functional groups needed to grab onto adhesives.
Experience in surface preparation.
With more than 20 years of experience in optimising the science of surface interfaces Jörg Eisenlohr and his team at Plasma Technology GmbH offer both support and development to resolve bonding problems.
- In the aerospace and the auto industry: Moulded composite parts need to be prepared to achieve a lasting bond under extreme stress. Not just structural components need to be reliably bonded but also ventilation systems for example.
- Medical applications: Often silicone insulations are used on cables that need sterilization. These need to be reliably bonded to connector backshells and provide good electrical insolation and prevent ingress from cleaning fluids. Here material compatibility is the main issue.
- Industrial applications: Our team has expertise in processinga wide range of products, even extremely small components can have their surfaces optimised for bonding. The life of high performance abrasion materials are improved by optimising the surface of the fine ceramic or diamond components the increase the bond strength to the carrier substrate,
At the other extreme, roll goods and sheet goods may need preparation before laminating.
Typical Process Information
- Vacuum Level: 0.1 - 2.0 mbar
- Gases: O₂, Ar, N₂, CF₄, and specialty mixtures
- Substrates: Polymers, Ceramics, Composites, Metals
- Cycle Time: Fully programmable 2–15 minute typical cycles
Capabilities and advantages of low pressure plasma surface preparation.
Major advantages of low pressure plasma surface modification for good bond strength is that they are inherently clean and dry.
Plasma cleaning, etching and priming can be performed in a single process with a small footprint saving space, time and cost.
The complete process is environmentally friendly, no cleaning or aggressive etching fluids, just a small amount of gas for the erection and to transport the contamination from the chamber.
Process parameters can be stored and protocoled ensuring reliability and repeatability. The constant feed of small amounts of fresh process ensures no quality degradation that may occur with cleaning or etching fluids if not carefully monitored. No dust from abrasive surface roughening.
The equipment you need
Plasma systems for production, or small
tabletop plasma systems.
