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Project Quality Planning
Published in Davies A. Igberaese, Introduction to Project Management, 2023
It can be noted from all the definitions of quality above that it is as inexpedient to exceed quality as it is to fall short of quality. Delivering quality beyond the requirement of the customer is called Gold Plating. As a project manager, you should aim to meet set quality targets. Delivering extra quality would mean wasting resources and incurring additional cost which the customer may not be prepared to pay for.
Condensation, Evaporation, and Boiling
Published in Anthony F. Mills, Heat and Mass Transfer, 2018
If the condensate does not wet the wall, because either it is dirty or it has been treated with a nonwetting agent, droplets of condensate nucleate at small pits and other imperfections on the surface, and they grow rapidly by direct vapor condensation upon them and by coalescence. When the droplets become sufficiently large, they flow down the surface under the action of gravity and expose bare metal in their tracks, where further droplet nucleation is initiated. This mode is called dropwise condensation and is shown in Fig. 7.1. Most of the heat transfer is through drops of less than 100 ¼m diameter. The thermal resistance of such drops is small; hence, heat transfer coefficients for dropwise condensation can be very high: values of up to 300,000 W/m2 K have been measured. These high heat transfer coefficients are attractive to the design engineer; thus, considerable effort has been spent developing nonwetting heat exchanger surfaces, but no entirely satisfactory method has been found. If the surface is treated with a nonwetting agent such as stearic acid to promote dropwise condensation, the effect lasts but a few days until the promoter is washed off or oxidized. Continuous adding of the promoter to the vapor is expensive and contaminates the condensate. Bonding a polymer such as Teflon to the surface to promote dropwise condensation is expensive and adds an additional thermal resistance. Gold plating is also expensive and often does not have a lasting effect. When an industrial or laboratory condenser is put into service for the first time, the initial model of condensation is dropwise unless particular care is taken to clean the system. But in a matter of hours or days, a mixed mode of dropwise and film condensation will develop, and finally the condensation will be entirely film wise. Thus, current design practice is to always assume film condensation for a conservative estimate of heat transfer surface area.
Improved uniformity of Ni/Au coating on circuits by electroless plating
Published in Surface Engineering, 2019
Dongguang Liu, Heng Tian, Lijing Lin, Wenchao Shi
The traditional cyanide gold plating has been previously studied [13–15]. However, the thickness of as-deposited Au layer by traditional cyanide gold plating is less than 1 µm, which cannot meet the weld ability requirement of microstrip. In addition, the electrolyte solution of traditional cyanide gold plating is unstable [16]. Owing to the long-term use of electrolyte, the Au+ is dismuted, which could lead to the formation of Au tumour particles. The Au particles can be easily deposited onto the lines with the aid of mechanical stirring, resulting in the formation of tumours and burrs. The tumours and burr are easily connected to the nearby conductors, leading to the short circuit and the failure of pattern circuit [17,18]. At the same time, the precipitation of Au usually occurs on the ceramic substrate along the copper line due to the effect of activation procedure. The overflow of gold-plated coating could cause electrical short-circuit [19,20].