PCB通孔电镀铜添加剂的分子模拟及其作用机制的研究

工学博士学位论文


PCB 通孔电镀铜添加剂的分子模拟及
其作用机制的研究



博 士 研 究 生 ： 王冲
导 师 ： 安茂忠 教授
申 请 学 位 ： 工学博士
学 科 ： 化学工程与技术
所 在 单 位 ： 化工学院
答 辩 日 期 ： 2013 年6 月
授予学位单位 ： 哈尔滨工业大学

Classified Index: TQ153.1
U.D.C: 621.3



Dissertation for the Doctoral Degree in Engineering



STUDY ON MOLECULAR SIMULATION
AND MECHANISM OF THE ADDITIVES USED
FOR THROUGH-HOLE COPPER
ELECTROPLATING ON PCB

Candidate： Wang Chong
Supervisor： Prof. An Maozhong
Academic Degree Applied for： Doctor of Engineering
Speciality： Chemical Engineering and Technology
Affiliation： School of Chemical Engineering and
Technology
Date of Defence： June, 2013
Degree-Conferring-Institution： Harbin Institute of Technology


摘 要
-I-
摘 要
印刷电路板(Printed-Circuit-Board, PCB)是电子产品的必要组成部分，特别
是多层印制电路板的出现为电子产品向小型化、便捷化、智能化发展提供了基
础。通孔电镀铜是实现多层 PCB 层与层之间导通的主要途径之一，也是当今
PCB 制造工艺中非常重要的一项技术。但是在直流电镀过程中，由于通孔内的
电流密度分布不均匀，为了在孔内获得均匀镀层，使用有机添加剂是一个有效
而且经济的方法，但完全通过实验筛选添加剂是一项非常费时费力的工作。在
本文中，使用分子动力学(MD)模拟的方法对4 种整平剂候选物进行预测，并设
计了7 种复合添加剂体系，对负载通孔的PCB 板进行电镀，考察了添加剂体系
的均镀能力，利用电化学测试、原子力显微镜(AFM)、X 射线光电子能谱(XPS)
和量子化学计算手段对添加剂在阴极表面的行为和作用机理进行了探究。
通过动态极化曲线对比实验，选定了促进剂噻唑啉基二硫代丙烷磺酸钠
(SH110)和抑制剂聚乙二醇(PEG, MW=10000)，认为 SH110 是一种促进剂和抑
制剂或整平剂的结合体。使用分子动力学方法预测了两种新型整平剂：N-丁基
-N- 甲基溴化哌啶(PP14Br) 和氯化硝基四氮唑蓝(NTBC) ，并预测出与健那绿
B(JGB)有类似结构的藏红 T(ST)不是一种有效的整平剂。对 SH110 进行的分子
动力学模拟和电化学测试表明其可以作为通孔电镀封孔的单一添加剂。使用
SH110 和 PEG 分别做促进剂和抑制剂，设计了 4 种促进剂-抑制剂-整平剂和 3
种促进剂-抑制剂-走位剂体系。
利用预测和设计的添加剂体系，使用直流电镀的方法对不同厚径比和不同
孔径的PCB 通孔进行了电镀实验，验证了前文的分析和添加剂体系的性能，并
探索了添加剂的较佳使用浓度范围。使用通孔剖孔的方法检测了孔内镀层的均
匀程度，使用扫描电子显微镜(SEM)观察了镀层的微观结构。结果表明：当SH110
浓度为10mg/L 时，经过短时间电镀，就出现了“蝴蝶现象”，经过18h 电镀，实
现了超填充电镀封孔。对厚径比为 10 的通孔进行电镀，通过调节添加剂的使用
浓度，得到了 4 种均镀能力超过 90%的优良添加剂体系。这 4 种添加剂体系和
最佳使用浓度为：SH110 (1mg/L)-PEG (100mg/L)-PP14Br (20mg/L)，SH110 (1
mg/L)-PEG (200mg/L)-NTBC (3mg/L) ，SH110 (1mg/L)-PEG (200mg/L)-JGB
(1mg/L)，SH110 (1mg/L)-PEG (100mg/L)-脂肪胺聚氧乙烯醚(AEO, 10mg/L)。同
时验证了ST 不是一种有效整平剂的预测。对于厚径比为20 的通孔电镀，使用
SH110 (50mg/L)-PEG (200mg/L)-PP14Br (40mg/L)时，得到的均镀能力为 76.1%，
达到了对厚径比为20 的通孔的电镀要求。
哈尔滨工业大学工学博士学位论文
-II-
使用旋转圆盘电极，结合动态极化曲线、恒电流 E~t 曲线对添加剂的电化
学行为进行了测试，使用AFM、XPS 对添加剂的吸附行为进行了表征，使用量
子化学计算的方法获得并对比了一些添加剂的电子结构信息，系统研究了添加
剂在通孔电镀过程中的作用机理。结果表明：SH110 是一种促进剂和抑制剂或
整平剂的结合体，它可以在铜表面形成一层吸附膜，体现出抑制剂的作用方式，
这种抑制作用更容易出现在阴极的强对流区；其促进作用主要出现在阴极的弱
对流区，这是在通孔电镀中出现“蝴蝶现象”和实现超填充完美封孔的原因。
整平剂PP14Br 和NTBC 的加入不仅增大了镀液的阴极极化，而且增大了不同强
度对流下的阴极电势差值，这使得 Cu
2+
在孔口等强对流区受到的抑制作用更强，
有助于提升孔内镀层的均匀性。NTBC 会在阴极铜表面形成一个吸附层，此吸
附层导致了对Cu
2+
沉积过程的强烈抑制作用。JGB 可以影响阴极电势和阴极极
化，而 ST 对于阴极极化和阴极电势几乎没有影响。JGB 分子的最高占据轨道
(HOMO)值大于ST 的HOMO 值，表明JGB 具有更强的电子供给能力，这使得
JGB 能够通过向铜原子的空 d 轨道贡献电子成键而形成吸附，这种吸附作用最
终使得其可做为整平剂使用，而 ST 不具有这种作用。JGB 在铜表面的化学吸
附过程中，对氨基偶氮苯和 N=N 区域的作用比季铵化的 N 原子的作用强得多，
而ST 不具有这种结构，这很好地解释了ST 不是有效整平剂的原因。

关键词：PCB 电镀；添加剂；分子动力学模拟；均镀能力；高厚径比通孔













Abstract
-III-

Abstract
Printed circuit board (PCB) is the necessary component of electronic products,
and the emergence of multi-layer PCB helps to develope small, convenient,
intelligent electronic products. Through-hole (TH) copper electroplating is one of
the main methodes to realize the conduction among PCB layers, which is also very
important technology of PCB manufacturing process. It is very difficult to obtain
coatings with uniform thickness using traditional plating bacause of the uneven
distribution of current density in the TH during DC plating process. For obtaining an
uniform plating in the TH, using organic additives is an effective and economical
way. However, choosing and exploration of additives by experiments are very
time-consuming and laborious. In this paper, 4 levelers and 7 additive systems were
predicted using molecular dynamics (MD) simulation, and the TH were
electroplated using these additives. The uniform power (UP) of additives were
examined, and the actions of additives on the surfaces of cathodes and mechanisms
were explored by electrochemical test, atomic force microscopy (AFM), X-ray
photoelectron spectroscopy (XPS) and quantum chemical calculations.
The accelerator thiazoline dithio-propane sulfonate poly (ethylene glycol)
(SH110) which were considered as a combination of accelerator and inhibitor or
leveler agent and inhibitor PEG, MW=10000 were selected by electrochemical
comparative experiments. Two new levelers of N-butyl-N-bromide in piperidine
(PP14Br) and nitro blue tetrazolium (NTBC) were predicted using MD, and
Safranine T (ST) with the structure similar to Janus Green B (JGB) was predicted as
an uneffective leveler. The results of MD simulations and electrochemical tests
about SH110 indicated that SH110 could be used as a single TH plating sealing
additive. Accelerator-inhibitor-leveler and accelerator-inhibitor-walk agent systems
were designed by using SH110 and PEG as accelerators and inhibitors, respectively.
THs on PCB with different aspect ratio and hole diametres were electroplated
by DC using predicted and designed additive systems. The previous analysis and the
properties of of additive systems were verified and the preferred concentration scope
of additives were explored. The uniformity of the plating in TH was examined from
the view of cross sections of THs. SEM results indicated that butterfly technology
(BF) emerged after short-time electroplating and superfilling perfect sealing
generated after 18h electroplating when the concentration of SH110 was 10 mg/L.
Four excellent additive systems with UP more than 90% were obtained for TH
electroplating with the aspect ratio of 10 by adjusting the concentration of additives.
哈尔滨工业大学工学博士学位论文
-IV-
These 4 kinds of additive systems were SH110 (1mg/L)-PEG (100mg/L)-PP14Br
(20mg/L), SH110 (1mg/L)-PEG (200mg/L)-NTBC (3mg/L), SH110 (1mg/L)-PEG
(200mg/L )-JGB (1 mg/L) SH110 (1mg/L)-PEG (100 mg/L)-fatty amines, and
polyoxyethylene ether (AEO, 10 mg/L), respectively. The prediction of ST which
was not an effective leveler was also verified. The UP was 76.1% in TH with aspect
ratio of 20 using SH110 (50mg/L)-PEG (200mg/L)-PP14Br (40mg/L), which met
with the requirement of the TH with a aspect ratio of 20 in TH electroplating.
The electrochemical behavior of the additives were tested by rotating disk
electrode combination of dynamic polarization curves and constant current E~t
curve, and adsorption behaviors of the additives were characterized using AFM and
XPS. Electronic structure informations about some additives were obtained and
compared by quantum chemical calculations and the mechanisms of actions of the
additives in the Th electroplating process were studied. The results showed that
SH110 was a combination of an accelerator and inhibitor or a leveler, which may led
to the formation of adsorbed film on the copper surface and reflected the
performance of SH110 as an inhibitor. The inhibition of SH110 could take part in
strong convection zone of the cathode more easily, and the acceleration mainly
appeared in weak convection zone of the cathode, which accounted for BF and
superfilling during the TH eclectroplating. The addition of levelers of PP14Br and
NTBC not only increased the cathodic polarization of the bath, but also increased
cathode potential differences at different convection strength, which inhibited
copper ions in the area of convection at the mouth of TH more strongly and helped
to inhance the uniformity of plating inside the holes. NTBC could lead to the
formation of an absorption layer on the copper cathode surface, which caused strong
inhibition of copper ion deposition. JGB had an impact on the cathode potential and
cathode polarization, and ST had little effect on the cathode potential and cathode
polarization. The highest occupied molecular orbital (HOMO) value of JGB
molecular was larger than that of ST, which demonstrated that JGB having a
stronger electron-donating ability could be adsorped by contributing electrons to
empty d orbital of copper atom and bonding. The adsorption made JGB as a leveler
eventually but ST did not have the adsorption. The actions of aminoazobenzene and
N=N were much stronger than that of quaternized N atom during the chemical
sorption of JSB on copper surface, and ST did not have such a structure, which
explained that ST was not effect leveler.
Keywords: PCB electroplating, Additive, Molecular dynamic simulation,
Uniform power, High aspect ratio through-hole
目 录
-V-

目 录
摘 要 ....................................................................................................................... I
ABSTRACT ............................................................................................................ III

第1 章 绪 论 ......................................................................................................... 1
1.1 课题背景及研究的目的和意义 ................................................................. 1
1.2 电镀铜工艺的发展概况 ............................................................................ 2
1.2.1 常规电镀铜体系和工艺 ........................................................................... 3
1.2.2 印制板电镀铜发展概况 .......................................................................... 7
1.3 PCB 直流电镀铜添加剂研究现状 ............................................................. 9
1.3.1 PCB 电镀铜添加剂的发展 ....................................................................... 9
1.3.2 PCB 镀铜添加剂机理的研究进展 ......................................................... 12
1.4 分子动力学模拟和量子化学计算概况 .................................................... 13
1.4.1 量子化学计算方法 ................................................................................ 14
1.4.2 分子动力学模拟方法 ............................................................................ 15
1.5 本文的主要研究内容 ............................................................................. 16
第2 章 实验材料和研究方法 ................................................................................ 18
2.1 实验药品和所用仪器 ............................................................................. 18
2.1.1 实验药品 ................................................................................................ 18
2.1.2 实验仪器 ................................................................................................ 19
2.2 PCB 通孔电镀铜工艺 ............................................................................. 19
2.2.1 镀液配制方法 ........................................................................................ 19
2.2.2 PCB 通孔电镀前处理 ............................................................................. 20
2.2.3 PCB 通孔电镀实验装置 ......................................................................... 20
2.2.4 电镀工艺流程 ........................................................................................ 21
2.3 分子动力学模拟与理论计算 .................................................................. 21
2.3.1 分子动力学模拟 .................................................................................... 21
2.3.2 量子化学计算 ........................................................................................ 22
2.4 镀层性能和添加剂性能表征 .................................................................. 22
2.4.1 PCB 孔内镀层厚度检测 ......................................................................... 22
2.4.2 镀层外观和微观形貌表征 .................................................................... 23
哈尔滨工业大学工学博士学位论文
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2.4.3 添加剂在铜表面的吸附性能表征 ......................................................... 23
2.4.4 电化学分析 ............................................................................................ 24
第3 章 通孔电镀铜添加剂的选择和预测与体系设计 ......................................... 25
3.1 通孔电镀铜抑制剂和促进剂的选择 ........................................................ 25
3.1.1 抑制剂的确定 ........................................................................................ 25
3.1.2 促进剂的确定 ........................................................................................ 26
3.2 通孔镀铜整平剂吸附行为的分子动力学模拟 ......................................... 30
3.2.1 整平剂的初步筛选 ................................................................................ 31
3.2.2 PP14Br 的分子动力学模拟 ..................................................................... 32
3.2.3 NTBC 的分子动力学模拟 ...................................................................... 36
3.2.4 JGB 与ST 的分子动力学模拟 ............................................................... 40
3.3 单一添加剂条件下的通孔电镀 ............................................................... 45
3.3.1 SH110 的分子动力学模拟 ..................................................................... 45
3.3.2 SH110 的浓度选择 ................................................................................. 47
3.4 通孔镀铜添加剂体系的设计 .................................................................. 48
3.4.1 促进剂-抑制剂-整平剂体系 .................................................................. 48
3.4.2 促进剂-抑制剂-走位剂体系 .................................................................. 48
3.5 本章小结 ................................................................................................ 49
第4 章 添加剂的作用效果研究 ............................................................................ 50
4.1 厚径比为5 的通孔电镀 .......................................................................... 50
4.1.1 使用基础镀液电镀效果 ........................................................................ 50
4.1.2 使用SH110 作为单一添加剂电镀效果 ................................................ 51
4.2 厚径比为10 的通孔电镀 ........................................................................ 54
4.2.1 使用基础镀液电镀效果 ........................................................................ 54
4.2.2 使用SH110-PEG 体系添加剂电镀效果 ............................................... 56
4.2.3 使用SH110-PEG-PP14Br 体系添加剂电镀效果 ................................... 58
4.2.4 使用SH110-PEG-NTBC 体系添加剂电镀效果 ................................... 62
4.2.5 使用SH110-PEG-ST 体系添加剂电镀效果 ......................................... 63
4.2.6 使用SH110-PEG-JGB 体系添加剂电镀效果 ....................................... 66
4.2.7 使用SH110-PEG-走位剂体系添加剂电镀效果 ................................... 67
4.3 厚径比为20 的通孔电镀 ........................................................................ 70
4.3.1 使用SH110-PEG-NTBC 体系添加剂电镀效果 ................................... 70
4.3.2 使用SH110-PEG-PP14Br 体系添加剂电镀效果 ................................... 72
4.4 本章小结 ................................................................................................ 74
目 录
-VII-

第5 章 添加剂在通孔电镀中的作用机理分析 .................................................... 76
5.1 SH110 单一添加剂在封孔电镀中的作用机理 ......................................... 76
5.1.1 SH110 在铜表面的吸附行为 ................................................................. 76
5.1.2 SH110 的电化学行为 ............................................................................. 77
5.2 SH110-PEG-PP14BR 体系的作用机理 ..................................................... 78
5.2.1 动电位方法研究添加剂的电化学行为 ................................................. 79
5.2.2 恒流方法研究添加剂的电化学行为 ..................................................... 79
5.3 SH110-PEG-NTBC 体系的作用机理 ...................................................... 81
5.3.1 NTBC 在铜表面的吸附行为 .................................................................. 82
5.3.2 NTBC 的电化学行为 ............................................................................. 84
5.4 SH110-PEG-JGB/ST 体系的作用机理 .................................................... 85
5.4.1 SH110-PEG-JGB/ST 的电化学行为....................................................... 85