Abstract Surface changes of copper and copper coupons coated with organic solderability preservative (OSP) after accelerated aging were measured using UV Differential Reflectance Spectroscopy. A chemometric method has been developed that allows correlation of the spectroscopic results with independent measurements of the solderability of the copper and copper/OSP coupons using a wetting balance or sequential electrochemical reduction analysis (SERA). Based on the results of this study, a versatile instrument for the assessment of the solderability of printed wiring boards has been demonstrated. The instrument is currently in beta testing at several locations.