Stacked body and method of producing stacked body

A method of producing a stacked body in which a plurality of insulating base material layers made of thermoplastic resin are stacked, the method comprising steps of:

• stacking the plurality of insulating base material layers made of thermoplastic resin;
• forming a coil and a dummy pattern on at least one of the plurality of insulating base material layers;
• integrating the stacked plurality of insulating base material layers by applying heat and pressure to form the stacked body;
• and
• mounting an external element on the stacked body;
• wherein
• the external element is a chip;
• the coil includes a winding-shaped conductive pattern located on at least one of the plurality of the insulating base material layers;
• the dummy pattern is disposed outside of the coil as a pattern isolated from the conductive pattern of the coil;
• the dummy pattern extends along the coil;
• the stacked body includes a step at which a thickness of the stacked body is different in a stacking direction in which the plurality of insulating base material layers are stacked;
• and
• the dummy pattern is located between the coil and the step at a portion defining the step where the thickness of the stacked body is larger, and the step is located between the external element and the dummy pattern.