Portable composite bonding inspection system

Foreign materials (contaminants) will usually affect many other properties of the surface as well as affecting the adhesion. This allows the use of indirect or off-contact measurement of surface energy to evaluate the quality of the surface. Our approach is environmentally friendly, uses no consumables and is totally benign to the surfaces being bonded. In order to detect contaminants on a substrate, the optical reflectivity properties of the materials can be compared. Metals and composites have different reflectivity than organics, which have low reflectivity (i.e. high absorption). This can usually be seen in white light by using a selected part of the light spectrum to enhance visual contrast between the two materials. This is because the reflectivity of a material changes with the wavelength of light. UV light can cause fluorescence of a few materials but this limits performance for a versatile machine. Extending the range from UV through the visible spectrum to IR gives a greater opportunity to find a frequency band where the reflectivity of the contaminant and the substrate are furthest apart for maximum contrast and sensitivity. By electronically enhancing these differences in the image through custom software, we can increase the sensitivity range even further. Thus UV/Vis./IR instruments can locate the contaminants but cannot identify them. A second technique such as a Mass Spectrometer can be used to identify and quantify the contaminant, the system uses a an ion mobility mass spectrometer (IMMS) to analyze and identify the contaminants evolved from a surface. The contaminants are released from the surface by local heating such as an IR laser or decomposed by a UV laser drawn into the IMMS and identified. These instruments can perform this identification separately or it may be combined in a hand-held spectroscope for this purpose. By using at least two types of illumination and filtering conditions and to add or subtract the images through software, we can pick out characteristic signatures for contaminants such as silicone.