Electromagnetic wave shielding wiring circuit forming method and electromagnetic wave shielding sheet

An electromagnetic wave shielding wiring circuit forming method comprising the steps of:

• preparing a fine copper particle dispersion, by dispersing fine copper particles (P) into a disperse medium (s) selected from:
• (i) a disperse medium (S1) including an organic solvent (A) having an amide-based compound, an organic solvent (B) having a boiling point of 20° C. or higher at an ordinary pressure and having a donor number of 17 or more, and an organic solvent (C) having a boiling point exceeding 100° C. at an ordinary pressure and comprising alcohol and/or polyhydric alcohol;
• (ii) a disperse medium (S2) including an organic solvent (A) having an amide-based compound, and an organic solvent (C) having a boiling point exceeding 100° C. at an ordinary pressure and comprising alcohol and/or polyhydric alcohol;
• (iii) a disperse medium (S3) including organic solvent (C) having a boiling point exceeding 100° C. at an ordinary pressure and comprising alcohol and/or polyhydric alcohol;
• (iv) a disperse medium (S4) including 24 to 64 vol % of an organic solvent (A) having an amide-based compound, 5 to 39 vol % of a low-boiling organic solvent (B) having a boiling point between 20° C. and 100° C. at an ordinary pressure, 30 to 70 vol % of an organic solvent (C) having a boiling point exceeding 100° C. at an ordinary pressure and comprising alcohol and/or polyhydric alcohol, and 1 to 40 vol % of an organic solvent (E) having an amine-based compound;
• (v) a disperse medium (S5) including 30 to 94 vol % of an organic solvent (A) having an amide-based compound, 30 to 94 vol % of an organic solvent (C) having a boiling point exceeding 100° C. at an ordinary pressure and comprising alcohol and/or polyhydric alcohol, and 1 to 40 vol % of an organic solvent (E) having an amine-based compound;
• and
• (vi) a disperse medium (S6) including 60 to 99 vol % of an organic solvent (C) having a boiling point exceeding 100° C. at an ordinary pressure and comprising alcohol and/or polyhydric alcohol, and 1 to 40 vol % of an organic solvent (E) having an amine-based compound;
• (a) coating or printing the fine copper particle dispersion onto a substrate, to form a wiring pattern comprising a liquid film of the fine copper particle dispersion;
• (b) coating or printing a pigment dispersion including a black-colored inorganic pigment, overlappingly onto the liquid film of the fine copper particle dispersion;
• and
• firing the liquid film of the fine copper particle dispersion and the pigment dispersion, to form a sintered wiring having a two-layer structure comprising a sintered copper layer and a black-colored layer.