Viscosity Modifier
Chemical treatment of natural ricinoleic acid derivatives produces a waxy solid used to control the flow properties of solder pastes and flux systems. The inclusion of hydrogenated castor oil provides the necessary thixotropy to prevent the paste from slumping after deposition on the PCB. It creates a structure that thins under the pressure of the squeegee but recovers quickly once the force is removed.
Application Stability
Maintaining the shape of a printed solder brick is essential for preventing shorts and bridge defects in fine-pitch assembly. Because hydrogenated castor oil possesses a high melting point, the material remains effective throughout the ambient temperature variations found in a production facility. The molecules form a network of fine needles or fibers through hydrogen bonding.
This network supports the heavy solder particles and prevents them from settling to the bottom of the jar during storage. Effective loading levels are balanced to ensure that the flux can still clean the surfaces during reflow.
Residue Management
Thermal decomposition during the reflow profile must be complete to avoid leaving waxy contaminants. If hydrogenated castor oil is present in excess, it can interfere with the wetting of the copper pad. Cleanliness testing validates the removal of these organic additives.
