Cross-linking delaminating

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. 

Schrijver et al. [1988] patented a process that permits the preparation of impact-resistant blends with radiation-resistant polymer as the matrix, a radiation-crosslinkable rubber phase and a suitable compatibilizer, so that the final product does not exhibit delamination (Table 11.9). The process yields a mixture in which the optimum size and shape of the particles, as present in the matrix, are essentially fixed, and thus are retained throughout further processing, e.g., injection molding. The dispersed rubber phase becomes wholly or partly cross-linked as a result of the irradiation and remains anchored in the matrix, while the matrix itself is hardly... 

Where the loading of nanomaterial is increased, the resistance of nanocomposites towards different chemical media increases. This may be due to the more compact and cross-linked structure of the nanocomposites, along with a reduction of permeability characteristics compared to the pristine system. The delaminated structure of the nanocomposites reduces the permeability and, as a result, the various ions or species present in the different media cannot easily penetrate the surface as they have to follow an indirect path. A significant increase in the thermal degradation temperature and a decrease in the thermal degradation rate have also been observed in most of these nanocomposite systems where there is an increase in the amount of dispersed nanomaterial. This improvement of thermal stability in the nanocomposites systems is related to the well-dispersed nanomaterials, which hinder the diffusion of volatiles and assist the formation of char after thermal decomposition. 

Internal stresses act to reduce adhesion less external force is required to disrupt the adhesive bond. As film formation proceeds, Tg rises and free volume is reduced the film becomes fixed in unstable conformations, and internal stress increases (66). The stress can build up sufficiently so that spontaneous delamination occurs (67). Stresses also result from volume expansions, such as swelling of films by exposure to high humidity (67) or water immersion (68). As the rate of cross-linking increases, stresses increase, since less time is available for... 

Typically, with lightly cross-linked materials the shear failure is cohesive. This is also the case for physically cross-linked materials such as styrenic block copolymers, particularly at elevated temperatures. However, as the cohesive strength of the PSA increases and/or as the resistance to peel adhesion falls, the mode of failure will tend to switch to adhesive, normally initiated as a delamination from the substrate at the corners of the tape. As the delamination grows and the stress builds, failure can be rapid and catastrophic with the debond crack traveling interfacially, alternately along the substrate and the backing interface. 

Sufficient retainment of GOx typically involves an electrode matrix such as an ink or a paste. In order to ensure sufficient adhesion to the conductive trace, water uptake of the electrode matrix over time has to be limited to avoid partial or complete delamination. To this end, adhesion-promoting layers have been reported. Intimate contact of the diffusion barrier with the working electrode may again strictly rely on sufficient adhesive bonding and utihzation of an adhesion-promoting layer or rely on cross-linking of the diffusional barrier on top of the electrode. 

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