Copper foil substrates

For capacitors on copper foil substrates, yield of initial samples was an impressive 83-90%. Capacitance density ranged from 20-242 nF/cm this is approximately 50-100 times higher than that of laminated planar epoxyglass capacitors. 

Additive In the additive process, formation of the conductor pattern is accomplished by adding copper to a bare (no copper foil) substrate in the pattern and places desired. This can be done by plating copper, screening conductive paste, or laying down insulating wire onto the substrate on the predetermined conductor paths. 

For manufacturing of negative electrodes, suspensions containing 45wt% powder of the carbon material being examined, 5wt% PVDF, and 50wt% of the solvent. Copper foil with thickness of 0,02 mm was applied as substrate. 

Note 3 The substrate is usually a sheet-like woven or non-woven material (e.g., glass fabric, paper, copper foil). 

The foil was fixed on the substrate with cyanoacrylate adhesive, and then the wafer on the foil. Finally the gold layer of the detector was covered with a 10ym thick copper, both ends of which were fixed on the sides of the substrate. The copper foil conducts the current from the detector to the ground and, on the other hand, protects the detector from the scattered beam and low energy delta-rays from the target. Five detectors are assembled on an aluninum holder The annular detector is fastened with two screws by the back of the substrate and the four plain others are put upright arround the annular detectors. 

The manufacture of a three-dimensional circuit device from a molded plastic such as the demonstration part shown in Figure 1 differs from the traditional printed circuit board. Different imaging techniques are required due to the three-dimensional features of the devices. In addition, the metal comprising the traces on the surface of the substrate are now deposited rather than formed from the laminated copper foil. 

Adhesives in electrical applications involve laminates with metal substrates and often have to withstand high temperatures. The laminates are often fairly thin and reasonably flexible therefore fixed arm and T-peel procedures can be helpful in measuring their adhesive strength. For example, a BMI system was bound to copper foil of thickness 25 pm. Some fixed arm (where the base plate formed a bond with aluminium) and T-peel results for this system are summarised in Table 2 on 15 mm width specimens of length 150 mm. 

Several techniques can be used to produce the actual conductor paths on the PWB substrate. These techniques are depicted in Figure 1.12. Subtractive processing starts with a PWB coated on one or both sides with copper foil ranging in thickness between 5 and 70 im. In the case of doublesided PWBs containing plated-through holes, the holes are first drilled and... 

Flexible printed wiring laminates usually contain (but are not limited to) either a polyimide or a polyester [usually poly(ethylene terephthalate)] with copper conductors. These laminates are prepared in sheets or by roll-to-roll lamination, usually by means of an adhesive. Alternatively, direct fusion without an adhesive is used. Recent developments include the use of alternative substrate materials such as poly(ether sulfones), additive plating of copper, and casting of a polymer directly on the copper foil web. 

It is much more of a problem in the USA, because of the military influence, but there are now a range of products designed to cope with this weakness, such as laminates with polyimide/Kevlar or reinforced substrates with copper/invar/copper foils, or alternatively, use of compliant surfaces. 

The copper foil is subsequently covered with a photoresist layer that is patterned by lithography techniques to produce the desired circuitry. Areas of exposed, cross-linked resist protect the copper that is to remain on the board as circuitry. The unprotected copper that is not needed for the circuitry is etched away, usually with ferric chloride solution. At this point, the printed board must have the following characteristics the substrate has to be structurally sound (no delamination), and the copper conductor patterns have to adhere well to the substrate in addition, the assembly should have good dimensional stability, and it has to show good solderability (ability to withstand short exposures to liquid solder at temperatures around 250 C or higher) to allow for the connection of components and devices to the circuitry. 

TLCPs have many outstanding properties that uniquely qualify them for these high performance multilayer boards (12). Table 7 compares the applicability of LCPs with other state-of-the-art materials for electronic packaging. They can be made into very thin, self-supporting films (<50 J.m) with a controllable CTE. By processing LCP films as described above, circuit substrates can be manufactured with a CTE around 7 ppm/°C and thermal stability over 250°C. TLCPs do not require secondary resins for fabrication into MLBs, they can be thermally bonded to themselves and to copper foil. Control of molecular orientation has been shown to result in a substrate with the desired CTE of 6 to 7 ppm/°C for matching alumina, or 16 ppm/°C for matching copper. 

Metallized PI films are used in electronic applications, e.g. for flexible printed circuit boards. Conventional techniques for the fabrication use adhesive bonding to a copper foil. However, the demand for high density packaging of electronic apparatuses requires a further reduction in the thickness of these substrates. It is possible to sputter metal particles into the surface of the PI film at a thickness of 20 nm, which forms the intermediate layer for subsequent formation of a conductive layer of copper or a copper alloy. 

Polymer substrates were also metallized by evaporation. Prior to metal deposition, the specimens were cleaned in a 2 % aqueous detergent, rinsed and dried. A resistively-heated conical tungsten basket containing 99.99+ % purity copper foil served as the metal source. Typically 100-200 nm of metal was deposited in an Edwards E306A coating system. The chamber was evacuated to 2 x 10 4 Pa and held for at least 1 h prior to metal deposition in order to properly degas the substrates. Complete details of the evaporation procedure have been given previously... 

The copper substrate was a sputter-cleaned pure copper foil. On exposure of the copper foil to air, polyaniline was deposited onto it using a commercially produced polyaniline dispersion in an organic solvent (Ormecon GmbH). The sample was kept in air at room temperature and after a certain time in air was transferred back into the main chamber for analysis. XPS measurements were performed using... 

The first one is a four-element patch antenna array for off-body communication in the 60 GHz band. The antenna radiating elements were fabricated by laser cutting a 0.07-mm-thick flexible copper foil, deployed on a cotton substrate with a Shieldlt ground plane. Antenna performance was experimentally tested in free space and in... 

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