The TRS-80 Model 102 I'm trying to repair had a bit of green gunk on the pcb from battery leakage. I removed a chip and tried to remove the old solder on the pads of the PCB, except that the solder doesn't melt. Like, at all.
I checked other clean joints on the PCB and the solder melts normally.
I'm trying not to damage the pads so I don't want to get too aggressive. I put RMA flux, I tried fresh solder, I tried 700 degrees, I tried to make good mechanical contact. Nothing. The blobs of solder look the same after with the divot of the IC lead still there.
Does the battery juice modify the solder into another alloy, I don't know, solder hydroxide or something?
I'm going to scratch the solder off but I don't want to rip off the pads, you know?
Anyone ever experience hard to melt solder after a battery juice leak?