Terpene Chemical Stability and Composition Monitoring

Terpene based cleaning agents, such as Petroferm Inc.'s EC‐7,® are currently being used successfully for cleaning rosin based fluxes from a variety of electronics substrates. However, if rosin undergoes any thermal degradation during the various soldering operations, the effectiveness of the cleaning process becomes acutely dependent on the condition and control of the terpene bath. One of the problems associated with controlling the cleaning process is an ‘ageing’ effect of the cleaning solution as evidenced by a noticeable colour change, substantial increase in viscosity and decrease in cleaning effectiveness. There is, therefore, a critical need for accurately monitoring EC‐7 chemical composition during normal process use. FT‐IR was identified as a suitable analytical technique for convenient and accurate monitoring of the EC‐7 composition. The terpene and surfactant components of EC‐7 have characteristic fingerprints in the IR spectrum. Calibration curves were generated and used to determine the composition of ‘aged’ EC‐7 solutions. As rosin has its own unique IR absorption band, rosin contamination (bath loading) can also be easily determined. These studies demonstrated that the ageing process is governed by both the volatilisation and the oxidation of the terpene component in EC‐7, the relative rates being determined by the specific configuration of the cleaning equipment used.