Modeling of the Electroplating of a Through‐Hole Considering Additive Effects and Convection

Hazlebeck, David A.; Talbot, Jan B.

doi:10.1149/1.2085912

Cited by 14 publications

(12 citation statements)

References 21 publications

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“…[1][2][3][18][19][20][21][22] However, uneven current density distributions and difficult mass transfers inside the THs, especially for a high aspect ratio (AR), commonly result in a subconformal deposition (i.e., a low throwing power and a copper overhang at the TH mouth). [8][9][10][11][12][13][14][15][16] These physical issues have been overcome by the use of chemical additives in the copper plating solution, which changes the secondary current density distribution due to the adsorption, consumption and desorption of these chemical additives inside the TH during copper electroplating. [18][19][20][21][22] Two typical chemical additives are nitrotetrazolium blue chloride monohydrate (NTBC) 19,23 and tetranitroblue tetrazolium chloride (TNBT), 20,21 and their molecular structures are illustrated in Fig.…”

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confidence: 99%

Characterization of Through-Hole Filling by Copper Electroplating Using a Tetrazolium Salt Inhibitor

Lin

Yan

Yen

et al. 2013

J. Electrochem. Soc.

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Through-hole (TH) filling of an advanced printed circuit board (PCB) by copper electroplating is performed using a direct current (DC) plating method and a simple copper plating formula composed of a single organic additive, namely, nitrotetrazolium blue chloride monohydrate (NTBC). Copper is preferentially deposited at the hole center to form a butterfly-shaped copper cross-section in the filled TH during plating. Three key factors are identified for enhancing the filling performance via a center protrusion deposition in the TH and are characterized by practical filling plating results and cyclic voltammetry (CV) analyzes. The filling performance of the copper plating formula for the TH is sensitive to forced convection, chloride ion concentrations and H 2 SO 4 concentrations. An appropriate forced convection combined with weak accelerators [3-(Benzothiazolyl-2-mercapto)-propylsulfonic acid, sodium salt (ZPS) or 3-S-Isothiuronium propyl sulfonate (UPS)] pre-adsorbed on the copper seed layer of the TH can effectively shorten the fill plating time from 9 h to 5 h. The center-protrusion filling mechanism and the role of NTBC in the TH filling are discussed in this work based on the plating results and electrochemical analyzes.

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confidence: 99%

Characterization of Through-Hole Filling by Copper Electroplating Using a Tetrazolium Salt Inhibitor

Lin

Yan

Yen

et al. 2013

J. Electrochem. Soc.

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“…Many papers have studied and reported what fluid dynamics and mass transfer parameters are key for enhancing copper throwing power (TP) of a PTH. [1][2][3][4][5][6][7][8] Regarding the TP, it will be defined in the section of "Results and Discussion". Most of these papers focused on the primary and secondary current density distribution and convective mass transfer inside the through holes (THs).…”

Section: Introductionmentioning

confidence: 99%

Effects of Brighteners in a Copper Plating Bath on Throwing Power and Thermal Reliability of Plated Through Holes

Chen

Tsai

Hsu

et al. 2016

Electrochimica Acta

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“…[4][5][6] The dominant problem in the TH electroplating is that the uneven local current density contribution gives rise to an uneven plating thickness in the TH. 4,[7][8][9][10][11] According to the diffusion characteristics of ions in the electroplating process, 12 the concentration of Cu(II) decreased gradually from the mouth to the center in the TH without additives and agitation in the electroplating process. Moreover, the current density at the mouth is higher than that at the center of the TH.…”

mentioning

confidence: 99%

Through-Hole Copper Electroplating Using Nitrotetrazolium Blue Chloride as a Leveler

Wang

Zhang

Yang

et al. 2013

J. Electrochem. Soc.

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The interaction between nitrotetrazolium blue chloride (NTBC) and copper surface was investigated using atomic force microscope (AFM) and X-ray photoelectron spectra (XPS). NTBC was employed as a leveler in the through-hole (TH) electroplating experiments. The electrochemical behaviors of NTBC were evaluated using rotating disk electrode. The results indicate that NTBC is an effective leveler used for TH electroplating. NTBC could be adsorbed on copper surface to form an adsorption layer. The adsorption behavior of NTBC on copper surface indicates that NTBC could inhibit the copper electrodeposition, which provides favorable conditions used as a leveler. In the TH electroplating experiments, a flat copper plating with uniform thickness in the TH was obtained when 3 ppm NTBC was added. The addition of NTBC could increase the cathodic polarization, which is attributed to the adsorption of NTBC on the cathode in the process of TH electroplating. The increase of potential difference at 100 and 1000 rpm with the addition of NTBC proves that NTBC is an effective additive used for TH electroplating.To meet the demands of state-of-the-art electronic products, Printed Circuit Boards (PCBs) with multilayer motherboards are necessary. 1-3 The metallization of the through-hole (TH) by copper electroplating, used to interconnect the layers of multilayer-PCB, has been an important technology in the fabrication of multilayer-PCB. [4][5][6] The dominant problem in the TH electroplating is that the uneven local current density contribution gives rise to an uneven plating thickness in the TH. 4,7-11 According to the diffusion characteristics of ions in the electroplating process, 12 the concentration of Cu(II) decreased gradually from the mouth to the center in the TH without additives and agitation in the electroplating process. Moreover, the current density at the mouth is higher than that at the center of the TH. 4,7-11 So much more copper ions are deposited at the mouth of the TH. 7 The plating thickness at the mouth (high current density) is thicker than that at the center (low current density) of the TH.Considering the stability of the PCB and the entire electronic system, it is necessary to obtain a plating with uniform thickness in the TH. 7,13 One of the most effective methods is using additives. The additive system, used for PCB electroplating, generally includes accelerator (i.e., bis(3-sulfopropyl) disulfide), inhibitor (i.e., poly(ethyleneglycol)) and leveler (i.e., Janus Green B). 1,14-16 The synergy of these additives leads to an uniform plating in the TH. 1 Leveler plays an important or decisive role in the accelerator-inhibitor-leveler system. [17][18][19] It is a very time-consuming work to search or design additives for TH electroplating. Until now, only few additives used for TH electroplating have been investigated clearly. 2,15,17 Wei-Ping Dow et al. obtained a full fill of TH without a void at the central position using nitrotetrazolium blue chloride (NTBC) as an inhibitor, but the current density adopted wa...

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Modeling of the Electroplating of a Through‐Hole Considering Additive Effects and Convection

Cited by 14 publications

References 21 publications

Characterization of Through-Hole Filling by Copper Electroplating Using a Tetrazolium Salt Inhibitor

Characterization of Through-Hole Filling by Copper Electroplating Using a Tetrazolium Salt Inhibitor

Effects of Brighteners in a Copper Plating Bath on Throwing Power and Thermal Reliability of Plated Through Holes

Through-Hole Copper Electroplating Using Nitrotetrazolium Blue Chloride as a Leveler

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