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The purpose of this paper is to study an electrolytic etching method to prepare fine lines on printed circuit board (PCB). And the influence of organics on the side corrosion protection of PCB fine lines during electrolytic etching is studied in detail.

In this paper, the etching factor of PCB fine lines produced by new method and the traditional method was analyzed by the metallographic microscope. In addition, field emission scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to study the inhibition of undercut of the four organometallic corrosion inhibitors with 2,5-dimercapto-1,3,4-thiadiazole, benzotriazole, l-phenylalanine and l-tryptophan in the electrolytic etching process.

The SEM results show that corrosion inhibitors can greatly inhibit undercut of PCB fine lines during electrolytic etching process. XPS results indicate that N and S atoms on corrosion inhibitors can form covalent bonds with copper during electrolytic etching process, which can be adsorbed on sidewall of PCB fine lines to form a dense protective film, thereby inhibiting undercut of PCB fine lines. Quantum chemical calculations show that four corrosion inhibitor molecules tend to be parallel to copper surface and adsorb on copper surface in an optimal form. COMSOL Multiphysics simulation revealed that there is a significant difference in the amount of corrosion inhibitor adsorbed on sidewall of the fine line and the etching area.

As a clean production technology, electrolytic etching method has a good development indicator for the production of high-quality fine lines in PCB industry in the future. And it is of great significance in saving resources and reducing environmental pollution.

The purpose of this study is to explore the mechanism of branch pits and tunnels formation and increase the specific surface area and capacitance of anode Al foil for high voltage electrolytic capacitor by D.C. etching in acidic solution and neutral.

Al foil was first D.C. etched in HCl-H₂SO₄ mixed acidic solution to form main tunnels perpendicular to the Al surface, and then D.C. etched in neutral NaCl solution including 0.5 per cent C₆H₈O₇ and Cu(NO₃)₂ with different concentration to form branch tunnels normal to Al surface. Between two etching, Cu nuclei were electroless deposited on the interior surface of main tunnels by natural occluded corrosion cell effect to form micro Cu-Al galvanic local cells. The effects of electroless deposited Cu nuclei on cross-section etching morphologies and electrochemical behavior of Al foil was investigated with SEM, polarization curve and electrochemical impedance spectroscopy (EIS).

The results show that sub branch tunnels can form along the main tunnels owing to the formation of Cu-Al micro-batteries, in which Cu is cathode and Al is anode. With increase in Cu(NO₃)₂ concentration, more Cu nuclei can be electroless deposited and serve as the favorable sites for branch tunnel initiation along the whole length of main tunnels, leading to enhancement in specific capacitance of anode Al foil.

Cu nuclei were electroless deposited on the interior surface of main tunnels by natural occluded corrosion cell effect to form micro Cu-Al galvanic local cells, which can serve as the favorable sites for branch tunnel initiation along the main tunnels to enhance specific capacitance of anode Al foil.

The pretreatment, electroplating and etching processes used by the PCB industry are unique in comparison with the plating industry generally. This paper deals with the treatment of the various sources of effluent, bearing in mind the stringent and strictly controlled quality standards. This paper also examines the various sources of effluent and the problems they present. The extent to which high purity water is required is discussed, as are the considerations to be made with regard to water recirculation and conservation in general.

The paper deals with the use of a Hydrogen Peroxide/Sulphuric Acid etchant in the Through‐Hole Plating system. The relative merits of this solution compared to currently used etchants such as Ammonium Persulphate are discussed on the basis of cost, convenience of operation and ecological effect.

Copper surfaces of laminates can be damaged by abrasively brushing prior to chemical processing. This is especially important where gold plated edge connectors are made to the latest Post Office specification of 2·5 µm. Chemical rather than abrasive treatment results in a pore‐free surface which is vital when the gold is thin.

Electrolytic Polishing. The continuous rotation of the electrolyte in the Shandon electro‐polisher is stated to prepare specimens for immediate microscopic examination. The electrolyte, drawn through the centrifugal pump, is pumped through a series of holes so that it contacts the specimen as a constantly rotating, continuously renewed liquid column. According to the manufacturers, this ensures a perfect polish and quality finish without flow lines. It eliminates cold working and false deformation structures and reduces specimen preparation to a mere routine instead of the highly skilled operation of mechanical polishing.

A lecture held in Paris the 22 April 1966 during an ESAB symposium on the subject of the development of methods for electrical welding, and originally published in Esab Svetsaren, no. 1, 1968 (Box 8850, S‐402 71 Göteborg 8, Sweden.)

The first part of this paper described scientific principles and methods for practical applications of electrolytic conductance tests on protective films on metals. This second part shows practical methods and procedures for obtaining and recording laboratory test data on the performance of protective coatings and of plastic tape‐wrap coatings applied to steel pipe as primary protection against corrosion.

In through‐hole plated double‐sided and multilayer printed circuit boards, electroplated copper forms the main electrically conductive path on hole walls. To ensure high reliability of electrical connection during component assembly, soldering and subsequent service, the properties of process solutions and deposits must be controlled. This paper discusses the methods of measuring and controlling copper plating processing parameters to achieve the optimum deposit properties. Plating pre‐treatment is discussed also as this can influence significantly process performance.

CHROME PLATING Cathodic potential in make‐and‐break of polarisation current. In order to understand the mechanism of electro‐deposition of metals considerable importance attaches to the study of cathode potential changes observable in the short interval of time between switching on or off of the polarisation current, especially with chromium, as previous Russian workers have noted (literature references are mainly Russian). But these do not satisfactorily explain all the observed phenomena. This is here attempted by means of oscillographic recordings of cathode potential changes, as per method described, using a bath containing (g./l.): 250 CrO3 and 5 H2SO4. Micro‐photographs are given of the oscillograms and of chromium structure. It is shown that, on switching in the current, a cathodic film is formed which is adsorbed on the surface. This proceeds the more quickly the greater the current density and higher the temperature, also the lower the sulphate concentration. With rise in temperature there is more interaction between the film formed and the chromium deposit, depending on the structure of this latter. Under the most widely used conditions in general practice it is concluded that the film formation is almost instantaneous when the current is switched on and intimate interaction thereof with the cathode surface. Ten references.— (M. A. Shluger, Zh. prikl. Khim., 1960, 33 (6), 1355–1359.)