Copper mirror test

These designators were determined by a series of tests, including the copper mirror test, a qualitative silver chromate paper test for chlorides and bromides, a qualitative spot test for fluorides, a quantitative test for halides (chloride, bromide, and fluoride), a corrosion test for flux residue activity, and a surface insulation resistance test at accelerated temperatoe and humidity conditions. 

The activators typically used in fluxes are corrosive. A flux can corrode the solder joint, copper traces and circuitry both before reflow and post reflow. That is, corrosion can occur during the assembly process subsequent to solder paste deposition, while the work is being processed through the assembly line. In addition, corrosion may result from the activators that remain on the board post reflow. A copper mirror test is used to determine the corrosive effect of the flux on a copper film deposited on a glass slide. The ability to classify flux activity levels helps to determine... 

A shiny copper mirror can be formed on the inside of a test tube in which the following reaction takes place. 

In order to investigate the relationship between the surface area of skeletal copper and activity, the same sample of catalyst was tested in four successive runs. Rate constants was compared with that of another sample prepared in the same way but pretreated in 6.2 M NaOH at 473 K before use. Figure 4 shows that the first order rate constants, calculated so as to take into account the mass of catalyst relative to the volume of solution, decreased in the first three cycles but then stabilised. The surface areas, measured on small samples taken after reaction, mirrored this pattern. The rate constant, and the surface area, for the pretreated catalyst was similar to those obtained in cycles 3 and 4. It is apparent that activity and surface area are closely related for the unpromoted skeletal copper catalyst and that the pretreatment in NaOH at 473 K is approximately equivalent to three repeated reactions in terms of stabilising activity and surface area. 

The copper methyl is unstable at the temperature of reaction and soon decomposes to metallic copper and free methyl radicals, the latter being identified by their ability to wipe off a mirror of lead on glass (the Paneth test). This decomposition occurs in about 0.003 second... 

Fehling s solution contains alkaline copper(ii) sulfate and the precipitate is copper(i) oxide. Tollens reagent is a solution of silver nitrate in ammonia, and the precipitate of metallic silver coats the inside of the test tube producing a mirror . 

Thompson, Wadsworth e Louat [52] testing mirror-polished specimens of polycrystalline high purity copper, found that if they would interrupt tests, from time to time, and electro polish a surface layer 2 pm depth, most of slip lines and bands would disappear with the exception of some that, instead, would persist. This was the sign of a surface damage that, though microscopic, was deeper than 2 pm. 

---