印制电路板高速电镀通孔的研究
发布时间：2018-11-01 13:42
【摘要】：金属铜具有良好的导电性和导热性,其镀层可用于实现印制电路板的孔金属化。由于电子产业的快速发展,印制电路板的尺寸逐渐减小,性能要求逐渐升高。这就要求板上的线路更精细,通孔的厚径比更高,镀层的稳定性更好。厚径比的升高使得镀液的分散能力降低,加大了孔金属化的难度。并且,随着印制电路板需求量的逐渐增大,需要提高电流密度,缩短电镀时间,采用高速电镀工艺,从而增大了电路板不同区域的浓差极化,对印制电路板电镀铜提出了更大的挑战。目前,通过新开发电镀添加剂,提高电镀液的均镀能力,可以较好地满足日益提高的电镀铜要求。本文从添加剂的作用机理入手,创立了新的添加剂性能评估方法,并通过实验验证了方法的准确性。采用循环伏安剥离法可以对抑制剂进行定性分析和定量分析,根据不同抑制剂的循环伏安曲线相似度来判断它们的性能差异;将镀液的循环伏安曲线与标准曲线对比,可以计算出镀液中的抑制剂浓度。采用计时电位法可以对电镀铜整平剂进行性能评估,铜沉积电位的负移幅度越大,表明整平剂对沉积电位的影响越大,整平性能越好。加入整平剂后,若电位负移幅度超过30毫伏,可对其进一步测试,采用这种方法对劣质整平剂进行初次淘汰。在电镀过程中,氧化还原电对会在镀液中发生氧化还原反应,与铜离子的沉积反应竞争消耗电能,降低电镀铜的电流效率,利用板面和孔内电流效率降低的程度不同,达到改善镀液均镀能力的目的。本文在镀液中分别加入硫酸铁和对苯醌这两种含有氧化还原电对的化合物,研究了它们对高速电镀铜的镀液性能的影响。结果表明,微量的铁离子不会改变电镀液的均镀能力;对苯醌会在镀液下实现氧化态和还原态的不断转换,影响电流效率,提高镀液的均镀能力,因此能够应用于电镀铜工艺中。在不同电镀条件下,有机添加剂在印制电路板上的吸附状态也有所不同。本文对镀液的重要成分配比进行了优化实验设计,得到了一组符合高速电镀铜的施镀参数,并发现光亮剂是高速电镀的重要影响因素。在优化控制条件下,对厚径比为6.4:1的通孔(Φ=0.25 mm)进行电镀实验,并对其进行了镀层性能测试,镀液的均镀能力能达到80%以上,孔径的微观形貌无瑕疵。将这一参数用于其他厚径比的通孔电镀,也得到了较好的结果。最后通过改变电流密度和搅拌强度,研究了它们在高速电镀中的作用。提高电流密度虽然能加快铜沉积速率,但会降低镀液的均镀能力;搅拌能够对阴极表面传质产生一定影响,从而改善电流分布的均匀性。
[Abstract]:Metal copper has good electrical conductivity and thermal conductivity, and its coating can be used to realize the metallization of the hole of printed circuit board. With the rapid development of electronic industry, the size of printed circuit board (PCB) is decreasing and the performance requirement is increasing. This requires that the lines on the plate are finer, the ratio of thickness to diameter of the through hole is higher, and the stability of the coating is better. The increase of thick-diameter ratio reduces the dispersion ability of plating solution and increases the difficulty of pore metallization. In addition, with the increasing demand of PCB, it is necessary to increase the current density, shorten the electroplating time, and adopt high-speed electroplating process, thus increasing the concentration polarization in different areas of PCB. This paper presents a greater challenge to copper plating on printed circuit boards. At present, through the new development of electroplating additives to improve the plating ability of electroplating solution, can meet the increasing requirements of copper plating. Based on the mechanism of additives, a new method for evaluating the properties of additives has been established, and the accuracy of the method has been verified by experiments. The cyclic voltammetric stripping method can be used to qualitatively analyze and quantitatively analyze the inhibitors, and their performance differences can be judged according to the similarity of cyclic voltammetry curves of different inhibitors. By comparing the cyclic voltammetry curve with the standard curve, the concentration of inhibitor in the bath can be calculated. The performance of electroplated copper leveling agent can be evaluated by chronopotentiometry. The greater the negative shift of copper deposition potential, the greater the influence of leveling agent on deposition potential, the better the leveling performance is. After adding leveling agent, if the range of negative shift of potential exceeds 30 millivolts, it can be further tested, and the inferior leveling agent is eliminated for the first time by this method. In the electroplating process, the redox reaction will take place in the plating bath, and the electric energy will be consumed in competition with the copper ion deposition reaction, and the current efficiency of the electroplating copper will be reduced, and the reduction of current efficiency will be different from that of the plate surface and the hole. To achieve the purpose of improving the uniform plating ability of plating bath. In this paper, ferric sulfate and p-benzoquinone were added to the bath respectively. The effects of these compounds on the properties of high speed copper plating bath were studied. The results show that the average plating ability of electroplating solution will not be changed by trace iron ion. P-benzoquinone can realize the continuous conversion of oxidizing state and reducing state under the plating bath, which affects the current efficiency and improves the plating ability of the plating bath, so it can be used in the electroplating process of copper. The adsorption state of organic additives on printed circuit board is different under different electroplating conditions. In this paper, the optimum experiment design of the important composition ratio of the plating bath is carried out, and a group of plating parameters that accord with the high speed electroplating copper is obtained, and it is found that the brightener is an important influence factor of the high speed electroplating. Under the optimized control condition, the through hole (桅 = 0.25 mm) with a thickness to diameter ratio of 6.4: 1 was electroplated. The coating performance was tested. The average plating ability of the plating solution was over 80%, and the pore size was flawless. This parameter has been applied to other through hole electroplating with thick-diameter ratio, and good results have been obtained. Finally, by changing the current density and stirring intensity, the role of them in high-speed electroplating was studied. Although increasing the current density can accelerate the deposition rate of copper, it will reduce the average plating ability of the plating bath, and stirring can affect the mass transfer on the cathode surface to some extent, thus improving the uniformity of the current distribution.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ153.14
本文编号：2304090
[Abstract]:Metal copper has good electrical conductivity and thermal conductivity, and its coating can be used to realize the metallization of the hole of printed circuit board. With the rapid development of electronic industry, the size of printed circuit board (PCB) is decreasing and the performance requirement is increasing. This requires that the lines on the plate are finer, the ratio of thickness to diameter of the through hole is higher, and the stability of the coating is better. The increase of thick-diameter ratio reduces the dispersion ability of plating solution and increases the difficulty of pore metallization. In addition, with the increasing demand of PCB, it is necessary to increase the current density, shorten the electroplating time, and adopt high-speed electroplating process, thus increasing the concentration polarization in different areas of PCB. This paper presents a greater challenge to copper plating on printed circuit boards. At present, through the new development of electroplating additives to improve the plating ability of electroplating solution, can meet the increasing requirements of copper plating. Based on the mechanism of additives, a new method for evaluating the properties of additives has been established, and the accuracy of the method has been verified by experiments. The cyclic voltammetric stripping method can be used to qualitatively analyze and quantitatively analyze the inhibitors, and their performance differences can be judged according to the similarity of cyclic voltammetry curves of different inhibitors. By comparing the cyclic voltammetry curve with the standard curve, the concentration of inhibitor in the bath can be calculated. The performance of electroplated copper leveling agent can be evaluated by chronopotentiometry. The greater the negative shift of copper deposition potential, the greater the influence of leveling agent on deposition potential, the better the leveling performance is. After adding leveling agent, if the range of negative shift of potential exceeds 30 millivolts, it can be further tested, and the inferior leveling agent is eliminated for the first time by this method. In the electroplating process, the redox reaction will take place in the plating bath, and the electric energy will be consumed in competition with the copper ion deposition reaction, and the current efficiency of the electroplating copper will be reduced, and the reduction of current efficiency will be different from that of the plate surface and the hole. To achieve the purpose of improving the uniform plating ability of plating bath. In this paper, ferric sulfate and p-benzoquinone were added to the bath respectively. The effects of these compounds on the properties of high speed copper plating bath were studied. The results show that the average plating ability of electroplating solution will not be changed by trace iron ion. P-benzoquinone can realize the continuous conversion of oxidizing state and reducing state under the plating bath, which affects the current efficiency and improves the plating ability of the plating bath, so it can be used in the electroplating process of copper. The adsorption state of organic additives on printed circuit board is different under different electroplating conditions. In this paper, the optimum experiment design of the important composition ratio of the plating bath is carried out, and a group of plating parameters that accord with the high speed electroplating copper is obtained, and it is found that the brightener is an important influence factor of the high speed electroplating. Under the optimized control condition, the through hole (桅 = 0.25 mm) with a thickness to diameter ratio of 6.4: 1 was electroplated. The coating performance was tested. The average plating ability of the plating solution was over 80%, and the pore size was flawless. This parameter has been applied to other through hole electroplating with thick-diameter ratio, and good results have been obtained. Finally, by changing the current density and stirring intensity, the role of them in high-speed electroplating was studied. Although increasing the current density can accelerate the deposition rate of copper, it will reduce the average plating ability of the plating bath, and stirring can affect the mass transfer on the cathode surface to some extent, thus improving the uniformity of the current distribution.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ153.14
【参考文献】
相关期刊论文 前3条
1 ;Preparation and characterization of molybdenum powders with copper coating by the electroless plating technique[J];Rare Metals;2008年04期
2 李雪春;印制电路板的电镀铜技艺[J];印制电路信息;2004年05期
3 陈彦青;高厚径比多层板的电镀控制[J];印制电路信息;2001年11期
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