Modular surface mount circuit device and a manufacturing method thereof

A method for manufacturing a plurality of modular surface mount circuit devices, the steps comprising:

• providing first and second electrically insulating planar substrates, each having an outer surface and a joining face, and having a plurality of units defined by a plurality of crossing lines, at least one of the substrates having an annular groove in each of the units arranged in matrix on the joining face, and each of the substrates having a plurality of through holes formed along outer and inner peripheries of each of the annular grooves;
• forming a cylindrical connection in each of the through holes of each of the substrates;
• forming a radial connection on the outer surface of each of the substrates so as to connect opposite cylindrical connections;
• mounting an annular member made of magnetic material in each of the annular grooves;
• joining the first and second substrates at the joining faces;
• electrically and serially connecting the cylindrical connections and radial connections at each of the units so as to form a toroidal coil;
• mounting at least one electronic part on the outer surface of either of the first and second substrates at each unit;
• electrically connecting the toroidal coil and the electronic part with each other at each unit;
• coating the toroidal coil and the electronic part with an electrically insulating material;
• and
• cutting the first and second substrates along the crossing lines to provide an individual circuit device.