Does XTPL printing process require sintering? How does XTPL perform sintering?
XTPL unique printing system allows to obtain very precise nonconductive & conductive structures. To obtain conductive structures XTPL uses special nanoinks synthesized in the company’s laboratories. The composition of XTPL’s nanoinks is each time precisely adjusted to specific requirements and its formulation is protected by an international patent application. In case of conductive structures – essential in applications such as TCFs for touch screens or repairing broken metallic paths in fine electronics circuits (open defects repair) – sintering is required. In this case XTPL uses nanoinks with metal nanoparticles (e.g. Ag, Au, Cu). Since our printing method is very versatile and allows for obtaining conductive structures on any kind of conductive or nonconductive substrate (even flexible or not flat one) the company uses different types of curing depending on a specific application. The process of sintering itself is crucial to meet conductivity requirements. The structures are heated in order to evaporate carrier solution and fuse individual particles together to form a continuous layer. Metal nanoparticles have melting points much lower than the corresponding bulk metal because of thermodynamic implications of the very large curvature of the particle surface. Traditional sintering, used extensively, relies on heat transfer mainly by convection and gives a high degree of control and predictability. However, many substrates such as coated papers and plastic films have softening points below the required sintering temperatures. Convection heating may in those cases cause deformation of the substrate and therefore selective heating of conductive layers with minimal heat transfer to the substrate is here more effective option. In main application area for XTPL technology, which is printed electronics sector, the most recent method is electrical sintering. During this process electric current is run through the conductive structure in which the heat develops because of the resistive losses. Only very small voltage can be applied here not to damage individual structures and the whole advanced circuit. Amongst methods of sintering used for conductive structures we can also apply plasma & chemical sintering, laser sintering (very flexible & precise method of concentrating high power to a very small area, although quite complicated and expensive), photonic curing (process of exposing the metal layer to pulses of high power light) and lastly rather unusual method of microwave heating (an interesting alternative when the printed structures are thinner than the penetration depth of silver at the frequency of interest). XTPL printing system allows to print variety types of inks, suitable for all types of curing. Thanks to that we are able to respond fast and flexibly to the needs of our clients. When it comes to nonconductive structures the process of sintering is not needed.