| 摘要 |
PURPOSE:To prevent barrel crack, which causes deterioration of connection, by strongly roughing to become an uneven shape even after a shape in a through-hole is copper-plated. CONSTITUTION:An inner layer circuit made of polyimide as a core, and polyimide prepreg 3 is laminated together with epoxy prepreg 2, and opened. Thereafter, when an etching back is performed by using potassium permanganate solution in a pretreating step, the polyimide part of the inner wall of a through- hole is etched back, and copper-plated to form a bellowslike through-hole 6. The hole 6 is improved in shrinkage as compared with a normal cylinderlike through-hole against a stress of Z-axis direction by the feature of the shape of the hole 6. Thus, copper-plating for enhancing reliability of a stress in a X-axis direction to a thermal impact can be performed. |
