This is a fairly common occurrence. The lead/tin solder of the via starts to corrode which causes it to expand very slightly. This lifts the edge of the solder mask and the corrosion works its way underneath. The same thing happens if you get a deep scratch on your car.
I had the same fault on a Sharp PC-1500A yesterday. A trace broken right where it connects to a via. Jeff Birt From: M100 <m100-boun...@lists.bitchin100.com> On Behalf Of Doug Jackson Sent: Saturday, December 24, 2022 9:28 PM To: m...@bitchin100.com Subject: Re: [M100] Model 200 repair video It's surprising that the via was ope. Even with a bit of corrosive gunk it shouldn't have gotten under the soldermask.
