| 摘要 |
A method is provided for forming a high-resolution photoresist layer on a substrate, such as a metal-clad circuit board blank. A dry film is used which comprises a support sheet, a negative-acting, alkaline aqueous developable photoresist layer in direct contact with the support sheet, and a protective sheet. The protective sheet is removed and the photoresist layer is cut sheet laminated to the substrate. Then the support sheet is removed. The photoresist layer is baked until its exposed surface is non-tacky. Artwork is laid directly in contact with the non-tacky exposed surface, and the photoresist layer is exposed to actinic radiation through the art work. The photoresist layer is then developed in alkaline aqueous solution. The photoresist layer is highly resolved. Subsequent processing steps, such as plating or etching and stripping yield a printed circuit board having highly resolved lines and spaces. Photoresists of specific formulation are found to be bakeable to a non-tacky surface with minimal loss of photospeed. |
