用于精细印制电路的无粗糙化铜箔技术

Profile-Free Copper Foil for Fine Printed Wiring Boards

随着电子整机的多功能化、小型化,半导体元器件装配用的基板线条也逐渐趋于微细化。印制电路板一般用的铜箔(以下称为一般铜箔)表面都经过了粗糙化处理,在蚀刻成为线路时,铜箔的粗糙化部分嵌入粘合结构中很难蚀刻干净,所以不适合制作精细线条的印制电路板。为此,日立化成公司研发成功了一种表面不进行粗糙化处理,表面粗糙度在1.5μm以下,表面较平滑适合于制作精细印制电路的铜箔(以下称无粗糙化铜箔)。一般认为,表面平滑的铜箔其抗剥强度较低;但这种新开发的铜箔表面经过了特殊处理,仍然与低轮廓铜箔相当,保持0.7kN/m以上的抗剥强度。采用这种无粗糙化铜箔,以减成法可蚀刻成60μm线宽的精细线路,并顺利地进行无电镀镍/金工艺作业,减少了对镀液的污染。当前正处于高速度、大容量的信息化时代,使用这种新型铜箔的线路与一般铜箔者相比,同样是传输5GHz的信号,线路的衰减将降低8dB/m。此项技术将对高速印制电路板基材的研发起到积极作用。

A new profile-free copper foil hasbeen developed whose surface roughness（Rz） is less than 1.5 μm but that has satisfactory adhesion strength, The origina] surface treatment provided can afford good peel strength （0,7 kN/m or more） equal to that for the conventional roughened foil with sufficient reliability. With the newprofile--free copper foil. the conventional subtractive method is applicable to the wiring of 60 μm pitch o less, and the short-circuit fault of electroless Ni/ Au plating that is prone to occur in fine wiring will be restrained since the wiring is formed on a smoothersurface. Moreover, the transmission loss at 5 GHz will decrease by 8 dB/m since the surface roughness of the conductor line is decreased.