| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which generation of pinholes can be suppressed and a protective coating with thick film thickness can be formed on a circuit board.SOLUTION: A method for forming a protective coating includes: a first step S1 of supplying a first resin 1 having a viscosity A satisfying an expression of 30 mPa s≤A≤500 mPa s to a circuit board 100 in which an electronic component 5 is joined to a substrate electrode 7 formed on a substrate 4 and a space X with a height d satisfying an expression of 100μm≤d≤500μm is formed between the electronic component 5 and the substrate 4, by an amount to fill the space X, and covering at least the surfaces of the substrate electrode 7, the electronic component 5 and a junction 3 between the substrate electrode 7 and the electronic component 5 in a state after being cured; a second step S2 of hardening the first resin 1; a third step S3 of supplying a second resin 2 on the surface of the cured first resin 1, the second resin 2 compatibilized with the first resin 1 and having a viscosity B satisfying an expression of 500 mPa s<B≤5000 mPa s; and a fourth step S4 of hardening the second resin 2. |
