In our circuit， PESD18VF1BSF and a 68 K ohm resister was placed in parallel, but when we do the ICT test after SMT, the resistance of some resistor is about 25K (not 68K), I have removed the ESD diode , the cosmetic looks good, and the resistance returned to normal, then detected the resistance of ESD, the data is about 40K(No ESR data was provided in datasheet), but when we left the ESD alone several hours, it changed to infinite, is there any problems? Then we placed the ESD back to the PCB, this resistance error problem was still appear intermittently. We have test some good samples, this problem would also appear. So is the phenomena OK? Or some other problem? what should be the right resistance?
Tester: Agligent 34401A