Method of manufacturing semiconductor device and method of treating electrical connection section

A method of manufacturing a semiconductor device, comprising:

• providing an electrical connection section and a protective film, the electrical connection section being electrically connected with a semiconductor substrate, a first part of the protective film covering at least a first area of a first surface of the electrical connection section, the first part of the protective film having a first face facing the first area of the first surface of the electrical connection section and a second face opposite to the first face, the protective film having an opening disposed on a second area of the first surface of the electrical connection section;
• applying a paste containing acid on the second area of the first surface of the electrical connection section and the second face of the first part of the protective film after providing of the electrical connection section and the protective film;
• removing the paste from the second area of the first surface of the electrical connection section by washing the electrical connection section;
• providing a solder to the electrical connection section through a flux after the removing of the paste;
• and
• providing the solder in such a manner that the solder is in touch with the second area of the first surface of the electrical connection section after the providing of the solder to the electrical connection section.