Hard gold

In the electronics industry, gold is used as fine wires or thin film coatings and frequendy in the form of alloys to economize on gold consumption and to impart properties such as hardness. Gold has properties that satisfy specific requirements not achievable with less expensive metals (see Electrical connectors Electronics coatings Thin films). 

The development of new alloys as a means of modifying existing electrodeposits for example the production of hard gold by alloy codeposition of copper, cadmium etc. to yield 23 or 18 carat alloys, or the use of zinc alloys for improved electrogalvanised coatings. 

The hardness of such coatings may reach a maximum of about 400 Hy as compared with approximately 50 Hy for a soft gold deposit. A series of corrosion studies in industrial and marine atmospheres by Baker" has indicated that the protective value of hard gold coatings is comparable with that of the pure metal, and that a thickness of only 0-002 5 mm gives good protection to copper base alloys during exposure for six months. 

Resuspend the soft gold pellet in 1.5 mL PBS with 0.04% PEG. The hard gold pellet is uncoated gold. 

The hard gold is used in electrical connectors, printed circuits boards, and mechanical arrays and it is produced by electrodeposition. The electrolytic methods (electrodeposition) are not discussed in this chapter. 

Titanium nitride is deposited on watch bands and jewelry as a hard gold colored coating. 

Figure 6.5. (a) TEM of crystalline gold colloid particles (the halo of organic molecules is invisible), (b) computer simulation of a dendrimer nanocomposite, (c) HRTEM of a gold nanocomposite particle containing 14 Au atoms. (D) Dendrimer template. CNDs are in the middle of the structural "spectrum", to the far left lie dendrimer compatibilized "hard" gold nanoparticles, and "soft" dendrimers are on the right. 

EDGE CONNECTORS HARD GOLD PLATING TAB 60/40 TIN-LEAD SOLDER... 

Dimple structure of flexible circuits is a low cost solution for the non-permanent termination. Multiple dimple arrays can be formed on the polyimide base or PET base flexible circuits by simple pressing processes. (Details are shown in Fig. 62.13) A typical example of the dimple termination is the connection of the disposable cartridges of ink jet printers. Over 60 dimples with hard gold plating are formed at the end of flexible circuit for the connection with the ink cartridge. The dimple arrays can make reliable connections over one thousand times. 

Contact probe array 200 -1000 Microbump array hard gold plating on nickel... 

Chromium, nickel, rhodium, or hard gold are used for wear. 

And, I think, it would be answered here, It would not to him be a new Species, no more than congealed Geliy, when it is cold, is a distinct Species, from the same Geliy fluid and warm or that liquid Gold, in the Fornace, is a distinct Species from hard Gold in the Hands of a Workman. 

Acid Neutral Alkaline Hard gold Soft gold Color gilding (flash deposition) Gold alloy Electroformed gold... 

Basic Formulations of Neutral and Acid Baths for the Electrodeposition of Soft Gold and Additive-Free Hard Gold (AFHG) (Concentration in g L )... 

Example formulations of acid baths for the electrodeposition of hard gold deposits are reported in Table 11.7 [2,61]. 

Acid Au(III) cyanide baths were introduced for industrial applications in the late 1970s see Wilkinson for a short account of its development [22], and have seen an increasing use since then. The main limits of Au(III) cyanide baths are the corrosiveness, the low rate of deposition, and the comparatively inadequate wear resistance when used as a contact finish, compared to hard gold from acid Au(I)-cyanide electrolytes. The acid Au(III) bath are especially recommended for deposition onto difficult to plate materials (because of passivity) such as stainless steel and chromium. They are currently also formulated for decorative plating (rack and brush) in a range of color shades and for deposition of thick, ductile coatings. 

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