Foils, etching

Some Cu substrates have been used, including Cu foils, etched foils, and vapor deposited Cu on glass. There does not appear to be a significant difference in the quality of deposits formed on Cu vs. Au, beyond those expected from considerations of lattice matching. 

There are two basic etchant needs to be met. The first is traditional foil etching for print and etch, plate/tent and etch, and pattern plate and etch. Virtually all processes in the United States and Europe use constant-rate systems for alkaline ammonia or cupric chloride etchants for this purpose. The second need is developing technology for specific precision very-fine-line etching—including foil thinning and thin metallization clearout for HDI constructions and fine features. (See Sec. 34.7 for additional discussion and mention of additional chemistries that may be useful for these applications.)... 

At Dubna, 280-MeV ions of 54Gr from the 310-cm cyclotron were used to strike targets of 206Pb, 207Pb, and 208Pb, in separate runs. Foils exposed to a rotating target disc were used to detect spontaneous fission activities. The foils were etched and examined microscopically to detect the number of fission tracks and the half-life of the fission activity. 

Figure 5 shows a typical metallic foil strain gauge. It consists of an etched grid of very thin foil attached to a thin insulating backing material. The... 

Most priated circuit board (PCB) production uses the subtractive process (41). In the simplest version, a thin copper foil is laminated to a nonconductor, holes are fabricated, and the unwanted copper etched off. These siagle-sided boards do not require plating. Known as ptint-and-etch, this version is used for the most simple priated circuit boards. 

There has been a continual increase in size and complexity of PCBs with a concurrent reduction in conductor and hole dimensions. Conductors can be less than 250 p.m wide some boards have conductors less than 75 pm wide. Multilayer boards greater than 2.5 mm thick having hole sizes less than 250 pm are being produced. This trend may, however, eventually cause the demise of the subtractive process. It is difficult to etch such fine lines using 35-pm copper foils, though foils as thin as 5 pm are now available. It is also difficult to electroplate holes having high aspect ratio. These factors may shift production to the semiadditive or fully additive processes. 

SemiadditiveMethod. The semiadditive method was developed to reduce copper waste. Thin 5.0 lm (4.5 mg/cm ) copper foil laminates are used, or the whole surface may be plated with a thin layer of electroless copper. Hole forming, catalysis, and electroless copper plating are done as for subtractive circuitry. A strippable reverse—resist coating is then appHed. Copper is electroplated to 35 p.m or more, followed by tin or tin—lead plating to serve as an etch resist. The resist is removed, and the whole board is etched. The original thin copper layer is quickly removed to leave the desired circuit. This method wastes less than 10% of the copper. 

Surface preparation of the core foil was originally simple acid etching. As the importance of durable surface treatments became known, a more stable chemical conversion coating with an organic primer-like coating became standard. Still, water ingression into honeycomb structure continued to cause the occasional... 

Sample pouches were then opened and both the food product and the film were examined at appropriate time intervals. The food product was examined for changes in texture, color, odor, and taste. The packaging material was checked for color changes, delamination, seal strength, etching of foil (if present), and any other changes noted. 

The micro structured platelets, hold in a non-conducting housing, were realized by etching of metal foils and laser cutting techniques [69]. Owing to the small Nemst diffusion layer thickness, fast mass transfer between the electrodes is achievable. The electrode surface area normalized by cell volume amounts to 40 000 m m". This value clearly exceeds the specific surface areas of conventional mono- and bipolar cells of 10-100 m m. ... 

Aluminum foil capacitors occupy an important position in circuit applications due to their unsurpassed volumetric efficiency of capacitance and low cost per unit of capacitance.328 Together with tantalum electrolytic capacitors, they are leaders in the electronic discrete parts market. Large capacitance is provided by the presence of extremely thin oxide layers on anodes and cathodes, and high surface areas of electrodes could be achieved by chemical or electrochemical tunnel etching of aluminum foils. The capacitance of etched eluminum can exceed that of unetched metal by as much as a factor of 50.328... 

Barrier anodic oxides covering the surface of aluminum etched foil are usually formed in borate or phosphate solutions. To improve capacitor characteristics, high-purity aluminum is desirable with as low a concentration of impurities as is acceptable in terms of cost. 

We made attempts to deposit 1 mp layer of P-tin film on 20 mp tungsten foil. This foil was previously etched in nitric acid. We showed by XRD the absence of Sn-0 and Sn-Mo bonds (Figure 2). Charge-discharge curves in all cases have sloping shape typical of tin (Figure 3). 

The f-phase precipitations form as white non-etching precipitations of 0.3-0.5 pm size both in non-deformed and deformed Fe-Ni foils (fig. 2). 

The spectrum of titanium metal foil is in Fig. 23. The foil, originally of 12/t thickness, was reduced by etching in HF to about 4/. A corresponding spectrum of titanium metal powder (not shown here) contained the same peaks but with only about half the amplitude, and with greater scatter of data points. This is an illustration of the advantages of having uniformity of thickness, which is especially difficult to achieve with metal powders. The titanium metal spectrum appears to be Kronig type fine structure. 

Institute of Technology (Reese et al., 2003). Using optical lithography to etch away photolithographic resists on stainless steel foils, french pens were designed with a rectangular geometry of 6 p in depfh, 30 p in width with 30 p sidewalls at the tips. To add structural support, the features anterior to the tip were expanded out so that the width of the sidewalls increased to 120 p with a trench width set at 90 p. 

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