A Model for Copper Electroplating of Multilayer Printed Wiring Boards

Kessler, Thomas; Alkire, Richard C.

doi:10.1149/1.2133018

Cited by 34 publications

(48 citation statements)

References 6 publications

(15 reference statements)

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“…Although theoretical and experimental studies of deposition distribution for similar geometries, such as through-holes [20][21][22][23][24][25][26][27][28] and trenches or vias [20,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47], are abundant, the nature of the deposition process for the geometry in the present study is vastly different from those in literature. In through-hole plating, concerns on mass transport deficiency are unwarranted since the inside of the holes is accessible to agitation because of their relatively large dimensions; the non-uniformity caused by reactant depletion is readily avoided by adequate agitation [20,21].…”

Section: Introductionmentioning

confidence: 99%

Theoretical studies of displacement deposition of nickel into porous silicon with ultrahigh aspect ratio

Zhang

et al. 2007

Electrochimica Acta

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Section: Introductionmentioning

confidence: 99%

Theoretical studies of displacement deposition of nickel into porous silicon with ultrahigh aspect ratio

Zhang

et al. 2007

Electrochimica Acta

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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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“…For the miniscale, two-dimensionless criteria for good plating quality have been analytically determined (2) …”

Section: Discussionmentioning

confidence: 99%

Investigation of Agitation Effects on Electroplated Copper in Multilayer Board Plated‐Through Holes in a Forced‐Flow Plating Cell

Engelmaier¹,

Kessler²

1978

J. Electrochem. Soc.

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The effect of electrolyte agitation in p l a t e d -t h r o u g h holes (PTH's) of multilayer boards (MLB's) is investigated for high conductivity CuSO4/H2SO4 electrolytes with and without brightener additives. The e x p e r i m e n t s were carried out in an 80 liter forced-flow plating system capable of agitation by air sparging also. PTH quality is assessed in terms of the PTH electrical resistance, the PTH deposit uniformity, and the deposit morphology. Correlations are made with plating current density, e l e c t r o l y t e v e l o c i t y in the PTH's, and two dimensionless plating parameters, ~T~ and j/j~ir~. The results show that for additive-free plating, the agitation requirements to prevent m a s s transport-limited plating conditions increase rapidly with increasing current densities and decreasing cupric ion concentrations. At the current densities common in MLB production, the low levels of agitation produced by air sparging alone provide only for marginal plating conditions particularly at the board edges where the test coupons are located. The plating criteria for good PTH deposits, ~TK ~ 1 and J-/Jlim ~ 0.25 are confirmed by the experimental results. Plating with Cubath| additives is shown to be considerably less sensitive to variations in the plating parameters which are lil~ely to occur in production. The criteria for good PTH quality can be extended to ~T~ ~ 2 and j/jlim ~ 0.25, which allows for more latitude for plating current density variations.Among the m a n y critical process steps that a multilayer printed wiring board (MLB) undergoes during its production, the electroplating of copper is one of the most important. MLB's contain p l a t e d -t h r o u g h holes (PTH's) which provide electrical connections between the various circuit layers of the MLB (see Fig. 1). During the electroplating step, copper is deposited in the drilled PTH's as well as on the outer MLB surfaces. Since the plating of PTH's in MLB's places much more complex demands on the plating process as compared to standard electroplated product, a better understanding of the plating process and its controlling parameters is necessary (1-3). Efforts have been reported which were designed to gain understanding either through analysis of the existing plating phenomenology (I, 5-12) or through analytical modeling (2-4, 13). P a r a m e t e r s were defined which provide a gauge for the relative importance of the three mechanisms (electrical characteristics of the plating solution, electrochemical kinetics of the plating reaction, and fluid dynamic conditions at the cathode) whose interaction determines the performance of an electroplating process. Different mechanisms become dominant for the copper distribution at the different scales important in the plating of MLB's: macroscale, miniscale, and microscale (3).T h e macroscale is characteristic of plating of complete panels. Plating at this scale is dominated by the p r i m a r y current distribution as long as sufficient electrolyte agitation at the cathode surface prevents...

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A Model for Copper Electroplating of Multilayer Printed Wiring Boards

Cited by 34 publications

References 6 publications

Theoretical studies of displacement deposition of nickel into porous silicon with ultrahigh aspect ratio

Theoretical studies of displacement deposition of nickel into porous silicon with ultrahigh aspect ratio

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

Investigation of Agitation Effects on Electroplated Copper in Multilayer Board Plated‐Through Holes in a Forced‐Flow Plating Cell

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