HVLP外层铜箔可靠性研究

Research on the Reliability of HVLP outer layer copper foil

随着PCB朝着多层化、薄型化、高密度化、高速化方向发展,尤其是5G高频高速信号传输对信号完整性的要求,HVLP铜箔应用逐渐增加。HVLP铜箔粗糙度小、轮廓低,高速信号传输时"趋肤效应"影响小、损耗低[1]~[4],但是抗剥强度相对偏低、可靠性风险高。文章主要研究HVLP铜箔在PCB加工过程中铲平刷板的机械磨刷和铜厚对成品可靠性的影响,测试了不同刷板方式、铜厚等条件下HVLP铜箔的抗剥强度,以及成品无铅回流可靠性测试。结果表明,铲平刷板的机械磨刷对抗剥强度无损害,铲平刷板后的铜厚对抗剥强度和耐热性的影响大。针对HVLP铜箔,需重点管控铜厚,否则可能会出现分层起泡等可靠性风险,本研究可以为同行研究处理类似问题提供参考。

With the development of PCB in the direction of multilayer,thinner,high-density,and high-speed,especially the requirements for signal integrity of 5G high-frequency and high-speed signal transmission,the application of HVLP copper foil is gradually increasing.HVLP copper foil has small roughness,low profile,small"skin effect"and low loss during highspeed signal transmission,but its peel strength is relatively low and reliability risks are high.This paper mainly studies the impact of mechanical brushing and copper thickness of the HVLP during PCB processing on the reliability of the finished product,and tests the peeling strength with different brushing methods and copper thickness,and the lead-free reflow reliability test.The results show that the mechanical brushing of resin grinding has no damage to the peeling strength,while the copper thickness after brushing has great influence on the peeling strength and thermal resistance.For HVLP copper foil,the copper thickness needs to be controlled,otherwise it may appear reliability risks such as delamination and blister.This study can provide a reference to deal with similar problems.