Methods of forming electronic assemblies with inverse opal structures using variable current density electroplating

A method of forming an inverse opal structure along a substrate that includes depositing polymer spheres along the substrate and electroplating the substrate and spheres at a first current density to form a first solid metal layer such that the spheres are raised from the substrate. The method includes electroplating the substrate and the spheres at a second current density to diffuse metals from the substrate and deposit the metal about the spheres. The second current density is greater than the first current density. The method includes electroplating the substrate and spheres to form a second solid metal layer disposed over the spheres, and removing the spheres to form the inverse opal structure disposed between the first and second solid metal layers. The first and second solid metal layers define planar interface surfaces disposed over a porous structure of the inverse opal structure.