\documentclass{standalone}
\input{./tikzpreamble}
\begin{document}
    \begin{tikzpicture}
        \node[anchor=south west,inner sep=0] (image) at (0,0) {\includegraphics[width=.7\textwidth]{../pics/mainpcb_back.png}};
        \begin{scope}[x={(image.south east)},y={(image.north west)}]
            \node[anchor=south west,inner sep=0, rotate=45] (image2) at (0.43,0.08) {\includegraphics[width=.47\textwidth]{../pics/wafer.png}};
            \draw[fill=white] (0.5,0.5) node {1} circle (.02);
            \draw[fill=white] (0.1,0.68) node {2} circle (.02);
            \draw[fill=white] (0.1,0.32) node {2} circle (.02);
            \draw[fill=white] (0.2,0.8) node {3} circle (.02);
            %\draw[fill=white] (0.1,0.16) node {4} circle (.02);

            \draw[red, ultra thick, arrows=<->] (0.245,0.66) to[out=-90, in=180] (.73, .32);
            \draw[blue, ultra thick, arrows=<->] (0.765,0.66) to[out=-90, in=0] (.26, .32);
        \end{scope}
    \end{tikzpicture}
\end{document}