Junior Member level 2
I am using KEMET make Ceramic Capacitor P/N# C1206C106J8RACTU (CAP CER 10UF 10V X7R 1206) connected to discharge Pin of SE555 Timer IC . The RC combination is to get 60Sec Output from SE55 are RA=2.7MΩ RB=2.7MΩ and C=10uF. With use of first batch of prototyping PCB boards I get SE555 Timer IC output as 68 Sec and with second batch of Production board I get output as 110 Sec. RA, RB and C values are same for all batches of PCBA. I have test results for more than Qnty 20 PCBA of production batch for same electronics 555 IC circuit the output value is not same and it ranges from 110 Secs to 179 Secs. The few difference points between prototyping board and production boards are; Prototyping boards were manufactured in 2015, used supplier 1 for fabricating boards, used Solder flux from supplier 1 and not conformal coated and production boards are manufactured in 2020, used supplier 2 for fabricating boards, used Solder flux from supplier 2 and are conformal coated. The Question I have is does these listed differences in tow batches of PCBA causes any leakage current from SE555 IC or its traces and the conformal coat has its effect on dielectric of Capacitor ? Because during testing it is seen that leakage current is causing increase in output timing.