Methods, systems, devices, and products for constructing a downhole tool electronics module. Methods may include creating a circuit board by metallizing at least part of a first surface on a first side of a substrate to define at least one metallized area on the first surface, wherein the substrate comprises a ceramic material and includes: the first side, including at least (i) the first surface, and (ii) an elevated surface elevated from the first surface, and a second side opposite the first side; flattening at least partially the elevated surface to a predefined first flatness to create a mounting portion by removing material from the elevated surface; attaching an electronics component to the first surface; and mounting the circuit board on an electronics carrier by adhering at least part of the mounting portion to a mounting surface on the electronics carrier. Flattening at least partially the elevated surface to the predefined first flatness may be carried out by removing the material by areal grinding.