Copper Adhesion

Table 4.18 Effect of benzotriazole primers on the strength of epoxy adhesive/copper joints [204]...

SEM scans the specimen surface with a high-energy electron beam. The microstructures of the deposited PAB films are studied in SEM as film surface and microtomed cross sections. For enhancing the contrast between PAB phases, partial dissolution (by solvent vapor) or erosion (by plasma treatment) may be needed. Furthermore, for preventing accumulation of the static electricity on the specimen surface, a thin layer of Au/Pt may be deposited. The specimens are placed on a platinized silicon wafer holder with a conductive adhesive copper tape. The modern SEM has high resolution. 

Protein-Based Adhesives. Proteia-based adhesives are aormaHy used as stmctural adhesives they are all polyamino acids that are derived from blood, fish skin, caseia [9000-71 -9] soybeans, or animal hides, bones, and connective tissue (coUagen). Setting or cross-linking methods typically used are iasolubilization by means of hydrated lime and denaturation. Denaturation methods require energy which can come from heat, pressure, or radiation, as well as chemical denaturants such as carbon disulfide [75-15-0] or thiourea [62-56-6]. Complexiag salts such as those based upon cobalt, copper, or chromium have also been used. Formaldehyde and formaldehyde donors such as h exam ethyl en etetra am in e can be used to form cross-links. Removal of water from a proteia will also often denature the material. 

Printed circuit boards manufacture is aided by the use of KMnO. Alkaline permanganate solution is used to remove resin smeared on the interior hole wall of multilayered printed circuit boards. Additionally the hole wall is etched, resulting in a surface with excellent adhesion characteristics, for electrodeless copper (250). The alkaline permanganate etchback system containing >60 g/L KMnO and 40-80 g/L NaOH at 70—80°C, is effective for difunctional, tetrafiinctional, and polyimide resin substrates, where the level of etchback is direcdy proportional to the immersion time (10—20 min) (251). 

Flame spray metallising is widely used for the protection of metal against corrosion, especially for in situ protection of stmctural members. The principal metal used for spraying of plastics is sine. Aluminum and copper are also used. If the distance from the part is too great, the zinc solidifies before it touches the part and adhesion is extremely poor. If the molten zinc oxidizes, conductivity and adhesion are poor. If the distance is too short, the zinc is too hot and the plastic warps or degrades. These coatings are not as dense as electrically deposited coatings because of numerous pores, oxide inclusions, and discontinuities where particles have incompletely coalesced. 

Zinc phosphate, Zn2(P0 2> forms the basis of a group of dental cements. Chromium and zinc phosphates are utilized in some metal-treating appHcations to provide corrosion protection and improved paint adhesion. Cobalt(II) phosphate octahydrate [10294-50-5] Co2(P0 2 8H20, is a lavender-colored substance used as a pigment in certain paints and ceramics. Copper phosphates exhibit bioactivity and are used as insecticides and fungicides. Zinc, lead, and silver phosphates are utilized in the production of specialty glasses. The phosphate salts of heavy metals such as Pb, Cr, and Cu, are extremely water insoluble. 

Isophthahc acid is also used in formulations for adhesives, inks (qv), wire enamels, and dental materials (qv). Copper isophthalate [10027-31-3] is an ingredient in algicides and fungicides (98). 

The patented wire is again cleaned with acid, rinsed, and brass plated just before the second drawing. The brass acts as a drawing lubricant and as well as an adhesive to mbber. The brass composition is typically 60—70% copper with 2inc as the remainder. The patented, brass-plated wire is drawn into filaments of 0.15—0.38 mm diameter. 

The bulk of synthetic industrial diamond production consists of the smaller crystal sizes up to 0.7-mm particle size (25 mesh). This size range has wide utihty in industry, and a significant fraction of the world s need for diamond abrasive grit is now met by synthetic production yielding thousands of kilograms per year. Because the raw materials are plentiful, synthetic production could, if necessary, supply the world demand for diamond abrasive. Development work continues in order to improve size and utility of the manufactured product and to realize the full potential of diamonds at minimum cost. An appreciable increase in performance has been obtained by coating the diamonds with a thin layer of nickel or copper, before incorporating them into wheels. The thin layer of metal apparendy improves adhesion and heat transfer. 

Adhesives in the Tire Industry. Cobalt salts are used to improve the adhesion of mbber to steel. The steel cord must be coated with a layer of brass. During the vulcanization of the mbber, sulfur species react with the copper and zinc in the brass and the process of copper sulfide formation helps to bond the steel to the mbber. This adhesion may be further improved by the incorporation of cobalt soaps into the mbber prior to vulcanization (53,54) (see Tire cords). 

When plating any substrate less noble than copper, only a few mg/L of dissolved copper in the acid baths can adversely affect adhesion. Coatings can be too thin to be visible, yet contribute to poor adhesion. Small additions of thiourea have been used to prevent copper immersion, but it acts as a potent inhibitor, and work should be re-electrocleaned after the acid. Work should be exposed to the mildest acid treatments possible. Over-etching should be avoided. 

Electroforrning is the production or reproduction of articles by electro deposition upon a mandrel or mold that is subsequendy separated from the deposit. The separated electro deposit becomes the manufactured article. Of all the metals, copper and nickel are most widely used in electroforming. Mandrels are of two types permanent or expendable. Permanent mandrels are treated in a variety of ways to passivate the surface so that the deposit has very Httie or no adhesion to the mandrel, and separation is easily accompHshed without damaging the mandrel. Expendable mandrels are used where the shape of the electroform would prohibit removal of the mandrel without damage. Low melting alloys, metals that can be chemically dissolved without attack on the electroform, plastics that can be dissolved in solvents, ate typical examples. 

Adhesives and sealants Aluminum forming Asbestos manufacturing Auto and other laundries Battery manufacturing Coal mining Coil coating Copper forming... 

Heterogeneous nucleation is most likely to occur when there is a strong tendency for the crystal to stick to the surface of the catalyst. This sticking tendency can be described by the angle of contact, 6, shown in Fig. 7.3 the smaller 6, the better the adhesion. Anyone who has tried to get electronic solder to stick to a strip of copper will understand this well. If the copper is tarnished the solder will just roll around as a molten blob with 6 = 180°, and will not stick to the surface at all. If the tarnished... 

The metal film is then electroplated with copper, and the metal part brazed to the copper plating. Adhesives, usually epoxy resins, are used to join parts at low temperatures. Finally, ceramic parts can be clamped together, provided the clamps avoid stress concentrations, and are provided with soft (e.g. rubber) packing to avoid contact stresses. 

The polysulphides are frequently used in casting mixes and to a less extent in coating, laminating and adhesive applications. Their value in casting and encapsulation lies mainly with their low curing shrinkage and flexibility in the cured state. Their tendency to corrode copper and the somewhat inferior electric insulation properties of the blends does lead to certain limitations. 

A very simple tape test was used to demonstrate that a significant increase in adhesion of copper to PS accompanied formation of this complex. Copper films applied to clean PS were easily removed when a tape was pressed against the copper films and then peeled away. However, copper films applied to PS that was treated with an oxygen plasma were never removed by the tape, indicating significantly increased adhesion. 

Adhesion of copper films to PMDA/ODA polyimide was determined by peel tests conducted on samples that were prepared by vapor-depositing a thin layer of copper onto the polyimide and then building the thickness of the metal layer to about 18 p,m by electrodeposition of copper. Results of the adhesion measurements correlated well with substrate pretreatment. When the substrate... 

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