Provided herein are, among other things, epoxy resin varnishes and methods of making and using the same. In some embodiments, the epoxy resin varnishes comprise at least a filler such as silica. In certain embodiments, the epoxy resin varnishes provided herein are used for making laminates such as copper clad laminates. In farther embodiments, the copper clad laminates provided herein are used for making printed circuit boards (PCBs).