Diffusion Bonding of Plastics
Carville developed the process of diffusion bonding Acrylic/Plexiglas in the 1960’s. The diffusion bonding process was originally developed for the production of avionic instrumentation panels for the aerospace industry.
This diffusion bonding process allows plastic materials to be joined without the use of adhesives to create a “pure” bond or weld which is transparent. The plastic material is joined at a molecular level which ensures that any future thermal expansion or contraction of the material will not have a detrimental effect on the mechanical stability of the part.
Carville further developed the diffusion bonding process in the 1980’s with a joint development project with a leading medical diagnostic company resulting in the manufacture of the world’s first diffusion bonded medical manifold for use in a clinical diagnostic (haematology) application. This bonding process is ideal for medical and life science applications as it avoids the use of solvents or cements, so the joints are clean and are ideal for where there is a requirement for no possible contaminants. Diffusion bonded joints are invisible to the naked eye and are very strong.
High Accuracy Bonding (HAB)
HAB is a bonding process developed by Carville in 2009 as an extension of the diffusion bonding technology. As the fluidic application demands within the medical sector have increased, chemistries have become more aggressive and sample sizes have reduced. These changes have resulted in a demand for smaller micro fluidic style devices in Acrylic/Plexiglas (PMMA) that can also be produced in alternative engineering grade materials such as Polycarbonate (PC) and Polyetherimide (PEI).
Carville have worked with InVitro Diagnostic (IVD), medical device companies and life science companies in general on the development of this new manufacturing technique. We have now supplied many production HAB manifolds to customers in Europe, Asia and the USA for multiple medical and life science applications for many years. Carville HAB offers:
- Smaller track sizes down to 150 microns
- Highly accurate track and feature alignment
- Minimal material stress
- Multiple channel shapes, mixing chambers and profiles
- Integration of sensors, mixing flees and other components
Today, almost all of Carville manifolds are joined using this advanced diffusion HAB process.
Where appropriate, Carville also use Polymerising cements or Solvent cementing to produce strong, optically clear joints that are cosmetically attractive, usually for particular inserts or features.
It is important that plastics joined with these methods are suitably heat treated to remove any internal material stress. Failure to heat treat may result in solvent induced stress crazing or cracking of the material.