Etch solvent

Our Electronic Chemicals group is an industry leader in most basic manufacturing of Wet Process Chemistries, from UHP Straights (100 ppt qualities). Custom formulated Wet Etch, Solvents and Solvent Blends, and Cleaning Products. 

Dry-etching techniques, in general, are methods by which a solid state surface is etched physically by ion bombardment or chemically by a chemical reaction with a reactive species at the surface or combined physical and chemical mechanisms. Under chemical methods, one distinguishes between wet etching (solvent, vapor, electrochemical) and dry etching in the gas phase. Depending on the mechanism, isotropic or anisotropic (directional) etch profiles are obtained. 

Fig. 2.17. Strengths of some single lap joints of aluminium bonded with an epoxy-polyamide adhesive on exposure to air at 43°C and 90% relative humidity for various times. Metal surface treatments are etching in chromic-sulphuric acid, O alkaline etching, solvent degrease, and phosphoric acid etching, (after Butt and Cotter ).

Apart from domain boimdaries, some of the defects in alkanethiol monolayers (pitholes) are created by the thiol itself 159] by etching processes. It was found that the solvent used for preparation also has some effect on the resulting defect density. 

Poly(phenylquinoxaline—arnide—imides) are thermally stable up to 430°C and are soluble in polar organic solvents (17). Transparent films of these materials exhibit electrical insulating properties. Quinoxaline—imide copolymer films prepared by polycondensation of 6,6 -meth5lene bis(2-methyl-3,l-benzoxazine-4-one) and 3,3, 4,4 -benzophenone tetracarboxyUc dianhydride and 4,4 -oxydianiline exhibit good chemical etching properties (18). The polymers are soluble, but stable only up to 200—300°C. 

Surface prqiaiation of the joint area may be required to remove oxides, grease, moisture, etc. (prior to adhesive application) by mechanical, solvent, etching or degreasing processes to facilitate wetting. 

Surface cleaning/etches. As with aluminum and titanium, the most critical test for bonded steel joints is durability in hostile (i.e., humid) environments. The fact that the problem is a serious one for steel was illustrated in a study [117] that compared solvent cleaned (smooth) 1010 cold-rolled steel surfaces with FPL aluminum (microrough) substrates. Although the dry lap-shear strengths were not markedly different, stressed lap-shear joints of steel adherends that were exposed to a humid environment failed in less than 30 days, whereas the aluminum joints lasted for more than 3000 days. 

PTFE IS insoluble in all known solvents and resists attack by most chemicals, although its surtace is readily degraded by alkah metal-anunonia solutions. Such solvated electron media etch PTFE to produce a brown-black layer quite unlike the onginal white, low-friction, nonstick surface... 

A characteristic of the group (a) of resins is that they air-dry solely by solvent evaporation and remain permanently solvent soluble. This fact, combined with the need to use strong solvents, makes brush application very difficult, but sprayed coats can be applied at intervals of one hour. A full vinyl system such as (o) possesses excellent chemical and water resistance. Many members of group (o) have very poor adhesion to metal, and have therefore been exploited as strip lacquers for temporary protection. Excellent adhesion is, however, obtained by initial application of an etching primer the best known of such primers comprises polyvinyl butyral, zinc tetroxy-chromate and phosphoric acid. 

---