| 摘要 |
PURPOSE:To have excellent bending and obtain a flexible printed wiring board superior in cost and productivity by uniformly removing 3-30% of its thickness from the surface of rolled copper foil by a chemical or phisical method before or after circuit formation. CONSTITUTION:There are two kind of methods for removing the surface of a rolled copper foil: one is a chemical method; and the other is a physical method. One of the chemical method is such that, for example, a board is immersed in sulfuric acid aqueous solution, ferric chloride aqueous solution, ammonia aqueous solution, or the like, or these aqueous solutions are uniformly sprayed on the board to remove. One of the physical method is such that, for example, the surface of the board is removed by buff, sand blast or the like. Because superior bending cannot be obtained when the thickness of removed copper is less than 3% and it is difficult to remove copper uniformly when it is more than 30%, the scattering of thickness and bending is very wide and the treating time is lengthened. Thereby, the bending is improved sharply and a flexible printed wiring board superior in cost and productivity can be obtained. |
