一种激光微细熔覆直写布线的新技术

激光直写技术因其不需要掩模就可以在绝缘基板表面直接制备各种高精度、复杂形状的导电层而受到广泛重视。但是，布线速度过低和工艺复杂一直是阻碍该技术工业化应用的瓶颈。提出了一种以导电金属粒子、有机成膜物质构成的复合导电浆料为熔覆物质，以有机环氧板为绝缘基板，采用CO2激光加热直接制备线路板的新工艺、新方法。所布导线宽度为350μm，布线速率为2～20mm／s，所用的激光功率为0～20W，光斑直径约为100μm。系统研究了激光直写导电层的组织结构特征、导线与基板的结合强度以及导线导电率的变化特征。结果表明，激光微细熔覆直写布线层与基材结合牢固，所布导线的电阻率与导电银颗粒的体积分数及激光功率的大小有关，工艺参数与材料配比合适时，导线电阻率可以达到10^-6Ωcm的数量级，能够满足工业应用的要求。最后，对普通环氧树脂板下激光微细熔覆金属导电浆料直写导线时导线的形成机理和导电机理进行了分析。

A New Technology of Conductive Line Preparation by Laser Micro-Cladding Metal-Organic Pastes on PCB Board

Laser direct writing technique has attracted much attention in the past years, as it can fabricate the conductive lines on insulator board directly without mask and with high precisions. However, the direct writing speeds are very low for the current techniques, which restrict its industrial applications greatly. In this paper, a new technology named laser micro-cladding technique is introduced, in which the metal-organic conductive pastes are used as the cladding materials, and the organic insulator resin boards are used as the substrate. The CO2 laser with the power of 0～20 W and the beam spot of 100 micron are used. The microstructure and the conductive properties as well as the bonding strength of the conductive lines with the substrate are studied. The results demonstrate that the conductive lines have excellent conductive properties and strong bonding strength with the substrate, which can satisfy the demands for industrial applications. Finally the mechanisms of the conductive line formation and conductivity are also analyzed.