Bleeding, solid surface adhesion

Lastly, and more importantly, suppliers have reformulated their standard adhesives to reduce or prevent bleedout. For example, the widely used Henkel s Ablebond 84-1 LMl (Low Mobile Ions), a silver-filled epoxy, was reformulated as a no-bleed version Ablebond 84-1 LMl NB (No Bleed). This NB version, however, was found to have reduced wettability to capacitor terminations and, as a result, yet another version (NBl) was formulated as a compromise. Adhesives that are 100% solids are more prone to bleedout than solvent-based types since they contain low-molecular-weight reactive diluents that have a greater tendency to migrate prior to complete curing. Some surface-related and material-related observations concerning bleedout mechanisms may be summarized as follows ... 

It is also common for pol3rmeric compoimds to form surface regions with compositions different from the bulk material, by selective diffusion of components. This process is termed blooming when the surface component is solid, and bleeding if it is liquid. Sulfur and fatty acid blooms can inhibit adhesion in rubber laminates (3). Laser desorption mass spectroscopy has been employed to identify surface species on vulcanized rubber (4). X-ray scattering methods for the study of polymer surfaces and interfaces have been reviewed (5). Other surface analysis techniques commonly used with polymers include attenuated total reflectance (6-8), electron microprobe (9), Auger electron spectroscopy (10), x-ray photoelectron spectroscopy (11), and scanning probe microscopic methods (12). Overviews on polymer surface analysis have been published (13,14). 

It is also common for some polymeric compounds to form surface regions with compositions different from the bulk material, by selective diffusion of components. This process is termed blooming when the surface layer is solid, and bleeding if the surface is liquid. Sulfur and fatty acid blooms can inhibit adhesion in rubber laminates.Gillberg has published an overview on polymer surface analysis. 

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