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Polyimide deposition of thick layers (50‐60 μm after soft‐bake) is very important in the field of microelectronics; in particular for fabrication of microwave circuits for telecommunications, micromachining applications, MCM‐D and, in general, for pattern transfer. Spin coating is, even in this case, the only method that can provide good results in terms of quality, repeatability and reliability. This paper discusses problems concerning the polyimide deposition process for obtaining thick layers with an uniformity value within 10% and studying the process itself from a mathematical point of view. In particular, the thickness variation versus frequency has been analysed, checking the mathematical model in which the dependence is ω^−K(K=0.5). It is shown that the polyimide behaves differently depending on the residual solvents at the end of the process and that the model is verified only if the solvents are completely evaporated at the end of the process also. This resolves a certain confusion in the literature where the value of K changes from 0.5 to 1 with different justifications.

Water-based graphite lubricants have good lubricity in the process of metal forming, especially for hot-rolling seamless pipe. Although the use of water as a working fluid system instead of conventional mineral oil has many advantages for the fuel consumption, post cleaning and a new type of lubricant, the graphite contaminated the machine and workers for its physical properties. From the global environmental protection viewpoint, it is urgent to develop a kind of benign material.

Magnesium hydroxide which has the average particle size of 10 μm was chosen as a base material without further modification and pretreatments. On the HT-1000 high-temperature tribometer, the influence of temperature and lubricant materials on the friction coefficient was studied. The tribological performance at 900^°C provided evidence under high temperature for exploring a new lubricant material.

Tap water-based brucite lubricant will open a new chapter in the industrial lubrication, effectively avoiding many unfavorable factors caused by graphite lubrication, such as conductivity, pollution and energy loss. Meanwhile, it expanded the application of brucite as flame-retardant agent, catalyst, water treatment agent and so on.

It is a new and environmental lubricant to tap water-based brucite lubricant. And specially, the preparation process of lubricant is simple and economical.