Enhanced ink mark reliability

The relationship between flame treatment and mark permanency is studied. Ultraviolet-cured ink marked plastic leaded chip carriers (PLCC) have been examined for the cause of mark permanency failures. The competence of the mark was evaluated using chemical, moisture, and mechanical tests. Ink to substrate type of failure was noted on packages which failed the tests. Results showed that packages subjected to flame treatment prior to ink marking performed a lot better than untreated packages. In adhesive tape pull, packages exhibited a tenfold increase in mark adhesion after treatment. Flame treatment using a mixture of hydrogen and oxygen is effective in improving ink adhesion on the plastic package surface. Detailed electron spectroscopy for chemical analysis (ESCA) and time of flight secondary ion mass spectroscopy (TOF-SIMS) showed the treated surface to have more oxygen-functionalized carbon, which can improve adhesion. Measurement of the actual contact angles of ink on flame-treated and untreated surfaces showed a significant improvement from 44° to 35°