Showing papers on "Electroplating published in 1993"

Electrochemistry of multilayer colloids : preparation and absorption spectrum of gold-coated silver particles

Abstract: Gold was deposited onto colloidal silver (mean particle size 76 A) in aqueous solution, and the composite particles were studied by spectrophotometry and electron microscopy. The deposition took place via electron transfer onto the silver particles by radiolytically generated free radicals and subsequent reduction of dissolved Au(CN)2- by the stored electrons. The method allows one to control the coating thickness. The optical spectra were also calculated using Mie theory and the optical constants of the pure metals. It was found that one monolayer of gold should be sufficient to mask the silver resonance band completely and that the gold plasmon band should develop more quickly than observed. The differences between the calculated and observed spectra are explained by possible alloying of the surface layer. © 1993 American Chemical Society.

Precision high rate electroplating cell and method

Abstract: A precision high rate electroplating cell comprising a rotating anode/jet assembly (RAJA) immersed in the electrolyte and having high pressure electrolyte jets aimed at the substrate (cathode). The high pressure jets facilitate efficient turbulent agitation at the substrate's surface, even when it consists of complex shapes or mask patterns. High aspect ratio areas receive similar degree of agitation (and replenishment) as areas of lower aspect ratios. As a result, thickness and composition micro-uniformities are substantially improved while utilizing significantly higher current densities and plating rates.

Electrochemical study of SiC particle occlusion during nickel electrodeposition

Abstract: Previous, published work conducted by the Bureau of Mines showed that chromium particle occlusion occurs as a result of particle collisions with the cathode surface. Conductive chromium particles within the electric field were also shown to cause a local rise in the cathodic current density on the area immediately adjacent to that particle. In order to research the effect of conductive particles vs. semiconductive particles on the occlusion process, nickel electrodeposition was studied in the presence of SiC particles and compared to previous studies on nickel electrodeposition in the presence and absence of Cr particles. The effect of semiconductive SiC particles on nickel electrodeposition was to catalyze the formation of H[sub ads] as well as Ni[sub ads][sup +] intermediates. Evidence of a H[sub ads] intermediate was obtained by current efficiency studies of Ni electrodeposition as well as X-ray diffraction and hydrogen analyses of the coatings made during electrodeposition.

Electrodeposition of Corrosion‐Resistant Ni‐Zn Alloy I . Cyclic Voltammetric Study

Abstract: The interaction between different reacting species involved in the initial stage of electrodeposition of nickel-zinc alloy was investigated. A cyclic voltammetric study indicates that codeposition of hydrogen and nickel occurs, with formation of two types of hydrogen-nickel solid solution, i.e., [beta]-Ni and [alpha]-Ni. This nickel hydride formation during Ni-Zn alloy electrodeposition was verified by analyzing the voltammograms of nickel, zinc, and Ni-Zn alloy during initial deposition on various substrates. The dissolution potential of zinc and nickel from electrodeposited nickel-zinc alloy spans a wide range (ca. 400 mV). The influence of the interaction between nickel, hydrogen, and zinc on the nucleation of nickel-zinc electrodeposition is reported in part II of this paper.

Galvanostatic Pulse and Pulse Reverse Plating of Nickel‐Iron Alloys from Electrolytes Containing Organic Compounds on a Rotating Disk Electrode

Abstract: Linear sweep voltammetry, galvanostatic pulse, and pulse reverse techniques were used to study the plating of nickel-iron alloys in the presence of organic additives. The effects of pulse current densities, i p , reverse current densities, i r , rotation speed of disk electrode, and the presence of organic additives on deposition of nickel-iron alloys are evaluated. The observed phenomena can be explained by the concentration depletion of reactants (or products), and the surface coverage of the additives on the electrode. A new formulation of the plating bath is defined

Electrodeposition of Metal Powders with Controlled Particle Grain Size and Morphology

Abstract: The processes of metal deposition can be categorized into three main groups each of which has different requirements with respect to the physical state of the cathodic product. In electroplating the crystal layer is required to be fine grained, smooth, strongly adhesive, and glassy, i.e., to be easily polished. In refining and electrodeposition relatively coarse grained, rough, but adhesive deposits are required. They have to be of high purity and firm enough to endure handling before melting and casting into shapes suitable for further processing. In metal powder production by electrodeposition, a controlled product particle size is necessary and the product is favored not to or weakly to adhere to the cathode. Generally, powder production requires other conditions than those in electroplating.

Oscillation device for plating system

Abstract: A method of and an apparatus for the electroplating of material onto substrates, such as computer memory disks, by use of a plating cell comprising cathodes, anodes, passive shields, filters, an oscillation system and an electrical power supply. Anodes and magnets are attached to the inside side walls of the plating cell. The magnets have a coating of an electrically non-conducting material covering it. Shields, each having a filter attached to it, are also fixed to the inside side walls. A pallet, having openings for holding disk substrates during electroplating, is placed between the shields in the plating cell. The disk substrates function as cathodes during electrolytic plating. The anodes and cathodes when electrically energized results in deposition of desired material, having uniform thickness, across the entire surface area of the substrate. The shields and the coated magnets function as current shields that control the flow of ions within the plating cell and thereby ensure uniformity of plating thickness at the substrate surface. The magnet also provides a radial flux pattern at the surface of the substrate to orient the deposit on the substrate surface. The oscillation system aids in attaining plating uniformity by ensuring a uniform replenishment of ions at the substrate surface. The pallet and the plating cell designs enable a large number of substrates to be electroplated simultaneously, thereby reducing the cost of plating the substrates.

Interconnect structures having tantalum/tantalum oxide layers

Abstract: A method of fabricating a high-density multilayer copper/polyimide interconnect structure utilizing a blanket tantalum/tantalum oxide layer that electrically connects all of the electroplating seed layers to the edge of the substrate; upon completion of the electroplating process, the excess tantalum/tantalum oxide layer is etched off to produce isolated conductor lines. A multilayer copper/polyimide interconnect structure may be fabricated by repeating this fabrication sequence for each layer.

High-density multilayer interconnection system on a ceramic substrate for high current applications and method of manufacture

Abstract: High density/heavy current hybrid circuit on a ceramic substrate, or other insulating board material, includes first screen printed silver, or copper, polymer seed layer for basic circuitry and bus bar around this circuitry outside the scribe lines, which is connected by removable silver filled polymer links with the circuitry and also the circuit elements are connected with each other by the same links in order to provide uniform electroplating. The links are protected before electroplating with a removable plating resist and they are removed after electroplating using an appropriate stripping solution. Then a permanent plating resist and dielectric polymer thick film isolation layer are applied (for crossovers) on which the second seed layer is applied, plating of the second metal layer occurs and so on until the desired number of layers are done. Thus, cure temperature is that of polymerization, high density, good heat dissipation conditions, heavy current capacity in all the layers and low manufacturing costs are achieved.

Method and plating apparatus

Abstract: A method of and an apparatus for the electroplating of material onto substrates, such as computer memory disks, by use of a plating cell comprising cathodes, anodes, passive shields, filters, an oscillation system and an electrical power supply. Anodes and magnets are attached to the inside side walls of the plating cell. The magnets have a coating of an electrically nonconducting material covering it. Shields, each having a filter attached to it, are also fixed to the inside side walls. A pallet, having openings for holding disk substrates during electroplating, is placed between the shields in the plating cell. The disk substrates function as cathodes during electrolytic plating. The anodes and cathodes when electrically energized results in deposition of desired material, having uniform thickness, across the entire surface area of the substrate. The shields and the coated magnets function as current shields that control the flow of ions within the plating cell and thereby ensure uniformity of plating thickness at the substrate surface. The magnet also provides a radial flux pattern at the surface of the substrate to orient the deposit on the substrate surface. The oscillation system aids in attaining plating uniformity by ensuring a uniform replenishment of ions at the substrate surface. The pallet and the plating cell designs enable a large number of substrates to be electroplated simultaneously, thereby reducing the cost of plating the substrates.

Tin and solder plating in the semiconductor industry : a technical guide

Abstract: Preface. Acknowledgements. Glossary of terms. Introduction. Basic electroplating. Surface preparation for plating. Plating operation. Plating process control. Plating quality assurance. Corrosion. Properties of tin, lead and tin-lead alloy. Tin plating. Tin-lead alloy plating. Plating quality problems. Chemical analysis. Choice of metal finishing. Waste treatment. Improvements and future trends. Index.

Composition and process for preparing a non-conductive substrate for electroplating

Abstract: The present invention is directed to an improved composition and process for preparing a non-conductive substrate for electroplating. The composition comprises 0.1 to 20% by weight graphite having a mean particle size within the range of 0.05 to 50 microns; 0.01 to 10% by weight of a water soluble or dispersible binding agent for binding to the graphite particles; an effective amount of an anionic dispersing agent for dispersing the bound graphite particles; a pH within the range of 4-14; and an aqueous dispersing medium. Optionally, the composition may contain an amount of a surfactant that is effective for wetting the through hole. The resulting graphite dispersion is capable of uniformly coating the through holes in either a double-sided or multi-layer circuit board prior to electroplating. Through holes that were treated with the disclosed graphite dispersion prior to electroplating were free of visible voids after electroplating.

Leadless ceramic package with improved solderabilty

Abstract: A method of fabricating a leadless ceramic package having improved solderability characteristics. The ceramic packages are singulated from the package array before electroplating. This eliminates the damage which may occur to the plating layer during singulation, and permits plating of base metal exposed by singulation. Furthermore, the plating solution is not required to penetrate small-diameter castellation holes, which would often result in incomplete electroplating of the castellation surfaces.

NiP electrodeposition on a rotating-disc electrode and in a jet cell : relationship between plating parameters and structural characteristics

Abstract: The electrolytic deposition of NiP coatings on a rotating-disc electrode and in a high flow jet cell laboratory apparatus has been investigated. From the current density profile along the cathode, the dependences of the phosphorus content and the coating thickness on the local current density were established for different bath compositions. With increasing local current density a steep transition from high to low phosphorus content in the NiP coatings produced was observed in each plating bath. This transition can be electrochemically monitored in the jet cell by polarization measurements. The structural characterization of the coatings revealed at 12 wt.% P a change of the as-plated structure from amorphous to crystalline. The weight per cent of P at which this transition in structure occurs was found to be independent of both bath composition and type of plating cell used.

Electroplating of superconductor elements

Abstract: Processes and techniques are described for concurrent electroplating of yttrium, barium and copper from aqueous solution onto a desired substrate (e.g., nickel, nichrome or silver). Compounds of these elements are dissolved in solution and then placed in a plating cell in which the cathode is the substrate on which the elements are to be deposited. After the elements have been deposited, they are oxidized to provide the desired perovskite structure. The process may be continuous or non-continuous.

Additive plating process

Abstract: A method for electroplating over a nonconducting substrate comprising the steps of applying a thin film of a non-metallic conductive coating having a surface resistivity not exceeding 100 megaohms over said substrate, applying an electrically nonconductive coating over said conductive coating, said nonconductive coating having imaged recesses therein and electroplating metal into said recesses. The method is particularly useful for the manufacture of printed circuit boards.

Unipolar and bipolar pulsed current electrodeposition for PCB production

Abstract: This paper is concerned with the study of square-wave unipolar pulse and bipolar pulse reverse electroplating and, particularly, the determination of pulse parameters to optimise through-hole plating rates and uniformity in the production of printed circuit boards (PCBs). The Wagner number, derived from cathode polarization behaviour in electroplating solutions, with and without plating additives, and under pulse plating conditions, was used to rationalize the data obtained. Fundamental predictions were found to compare favourably with results obtained from practical plating tests.

Soft magnetic film with compositional modulation and method of manufacturing the film

Abstract: A soft magnetic multilayer film is manufactured by an electroplating process using an electrolyte containing metal ions. The soft magnetic multilayer film includes soft magnetic layers composed of elements, and deteriorated-soft magnetic layers composed of the same elements and alternating with the soft magnetic layers. The soft magnetic layers are preferably different in composition from the deteriorated-soft magnetic layers. In addition, it is preferable that the metal ions contained in the electrolyte include at least two of Ni ion, Co ion, and Fe ion.

Surface treated steel strip with minimal plating defects and method for making

Abstract: In connection with a process of implementing galvanizing and galvannealing on steel strips containing highly oxidizable elements such as Si, Mn, P, Ti, Nb, Al, Ni, Cu, Mo, V, Cr, and B, after annealing in a continuous line or implementing electroplating after annealing, the present invention provides a method for restraining non-plating at low cost in a stable manner and a surface treated steel strip having minimal non-plating. By applying on at least one surface of a steel strip a Fe plating having a coating weight of 0.1-10 g/m 2 and an oxygen content of 0.1-10 wt %, followed by annealing and then zinc or zinc alloy plating, there is obtained a surface treated steel strip having minimal plating defects which includes a Fe plating layer immediately below a zinc or zinc alloy plating layer and a steel alloying element concentrated stratum immediately below the Fe plating layer. The Fe plating may be formed using an electroplating bath which contains 0.1-10 g/l of Fe 3+ and a carboxylic acid or an alkali metal salt thereof.

Solder bump fabrication by electroplating for flip-chip applications

Abstract: A step-by-step description of a solder alloy bumping process for flip-chip application is discussed. Emphasis is placed on a 75-/spl mu/m high bump, as plated, with a pitch of 125-/spl mu/m array pattern is successfully achieved using conventional positive photoresist masking. The under-bump metallurgy (UBM) is sputtered Ti/Cu. The Sn/Pb composition of solder alloy such as 60/40 or 5/95 and the etchants used on the exposed UBM are discussed. This process is compatible with other IC wafer processes. The solder bump reflow is achieved utilizing a rosin flux and hot plate which is closely controlled in temperature and environment. >

Copper foil for printed circuits

Abstract: There is provided a copper foil for printed circuits characterized by having a coating layer which contains zinc and zinc oxide, chromium oxide and nickel, and either or both of zinc and zinc oxide at least on the shiny side of a copper foil. The coating layer is formed by electroplating using a plating solution which contains either or both of zinc salt and zinc oxide, chromic salt and nickel salt. This copper foil resists discoloration upon exposure to high-temperature conditions of 180° C. for 30 minutes. Resist adhesion is also good. The amounts of deposits are preferably 60 to 80 μg Zn, 30 to 40 μg Cr and 5 to 20 μg Ni per dm2. The matt side of the copper foil may be treated to form thereon a single metal layer or alloy layer of one or more metals chosen from among Cu, Cr, Ni, Fe, Co, and Zn. The copper foil is suited for the fabrication of printed circuits with fine circuit patterns.

Method and apparatus for nickel electro-plating

Abstract: An apparatus for nickel electro-plating parts from nickel plating baths that use nickel sulfamate as a source of nickel has a tank containing the nickel plating bath and in which an anode and a cathode are immersed. A semi-permeable wall of sintered or polymer material separates a cathode compartment from an anode compartment.

Effect of nickel on the electrodeposition of copper

Abstract: The mechanism of copper electrocrystallization from various solutions has been investigated to determine the influence of foreign cations and, particularly, of nickel. The study was performed by cyclic voltammetry and scanning electron microscopy. In sulphate solutions the Na+ and NH4+ cations affect the copper deposition by changing the nucleation overpotential and the presence of nickel cations makes the copper deposition easier by decreasing the nucleation overpotentials of both copper and nickel. In chloride solutions, the strong adsorption of the chloride species prevents all other influences by blocking the active sites of nucleation and growth and, therefore, Na+ or NH4+ addition does not modify the copper deposition. Consequently, the nickel does not modify the nucleation overpotential of copper. Whatever the solution, sulphate or chloride, the anodic behaviour of the copper-nickel codeposits are similar to the anodic behaviour of bulk Cu-Ni alloys.

Diffusion of copper into gold plating

Abstract: The value of the room-temperature copper-gold interdiffusion coefficient derived by extrapolating from high-temperature measurements is an underestimate by several orders of magnitude. Plating copper with a gold film has several disadvantages. Two specimens were analyzed by using Auger electron spectroscopy. Once the full thickness of the gold film is penetrated, copper accumulates on the surface, and a layer of high concentration of copper exists immediately below the gold-air interface. Electrical resistivity of an alloy is much higher than the resistivity of either component. This high-resistivity layer may be localized within the skin depth of propagating electromagnetic waves; in cases where copper has reached the surface, it is permanently within the skin depth at any frequency. A nickel diffusion barrier, commonly applied between copper and gold, is unsuitable in many microwave and millimeter-wave applications because of ferromagnetism of nickel at room temperature. The compound that forms on the surface of untreated copper at room temperature in a reasonably clean atmosphere is cuprous oxide. Its properties make it a better alternative to gold in microwave and millimeter-wave engineering. >