| 摘要 |
PROBLEM TO BE SOLVED: To enhance heat resistance, adhesive properties and folding resistance and to enhance dimensional stability or particularly planarity after etching and circuit forming, by forming a second resin layer containing a polyimide resin having a larger thermal expansion coefficient than that of the polyimide resin on an upper layer than a first resin layer. SOLUTION: A polyimide resin for constituting a first resin layer is a heat resistant resin having an imide bond in a main chain of a polyimide, a polyamide, a polyester imide or the like. A polyimide resin for constituting a second resin layer to be laminated on the first layer is, similarly to the polyimide resin of the first layer, the heat resistant resin having the imide bond in the main chain. It is necessary that a thermal expansion coefficient of the polyimide resin of the second layer is larger than that of the polyimide resin of the first layer. In the case that a linear thermal expansion coefficient of the polyimide resin of the second layer is equal to or smaller than that of the polyimide resin of the first layer, planarity after etching and circuit forming is deteriorated. |
