ITO Coating vs ITO Film – Automotive Interior – Capacitive Touch

ITO acts as an integral feature on most robust capacitive touch solutions, due to its conductivity and high transparency being desired for most display or optically critical products.

ITO as a capacitive touch feature is usually utilised with an ITO film or an ITO coating directly onto the part. There are considerable differences in application, functionality, reliability and durability between the two solutions which all automotive interior designers and automotive overhead console manufactures should consider when choosing between the options.

An ITO coating can be directly applied to the part itself and Diamond Coatings have formulated a solution which can be applied to smooth, grained, textured, curved and 3D surfaces. This flexibility in coating allows interior lighting designers the freedom in creating a unique lighting design, compared to the limitations put on them by ITO film, which can only be applied to flat surfaces.

With Diamond Coatings ability to deposit coatings directly onto many substrate types and geometries, it gives freedom to automotive interior designers to consider other applications such as arm rest controls, centre console design, sun blind activation and heated cup holders.

Diamond Coatings unique Diamox recipe has been supplied on parts to the automotive industry since 2007, with a score of less than 1 PPM. Such a tight control on quality is testament to the robustness and longevity of applying our ITO coating directly to the part itself, compared to applying it to a film, which adds a considerable amount of failure modes to the process.

In opting for an ITO film as a capacitive touch solution, car manufacturers run the risk of exposing themselves to warranty claims as a result of the inadequacies of the film which is most commonly found to be the main failure mode in a capacitive touch light lens warranty claim. ITO film firstly undergoes the coating process itself, with a suitable film required for adhesion. Thereafter, the ITO film can only be applied to a flat surface and must be done so with an optically clear adhesive, which in itself can be prone to failures such as bubbling, delamination and functional issues as a result of.

A directly ITO coated part is optically superior compared to an ITO film. With reflection from every interface, an ITO film has double the amount of interfaces to that of an ITO coating, meaning that the film has a considerable amount less transmission, with far more reflected light.

With the Environmental and ESD compliances required in the automotive industry, the failure points and risks are far quicker with an ITO film compared to a directly ITO coated part, due to the increased failure modes added to the manufacturing process, as well as the weaknesses in the film as a substrate.

In addition to this, ITO films struggle to achieve the required conductivity for capacitive touch solutions, meaning that the carriers used for integrating the film with the PCB is usually mixed with another material such as silver, which is prone to oxidisation, giving the product a very limited lifetime. Diamond Coatings have formulated their own unique carrier for PCB integration, which is the same material used in carriers of various military, medical and aerospace projects, compliant with the rigorous test standards associated with these industries.

Diamond Coatings have an in-coating process which can allow for separation of zones on the lens, creating a multi-switch touch light, as well as the ability to tune the coating to create dimmer and slider switches too. ITO film on the other hand, can only be used for a single activated zone.

With the state-of-the-art coating plant and machinery purpose built by Diamond Coatings, they have managed to create a lean manufacturing process for capacitive touch lenses, enabling them to make the prices of a directly coated part far more competitively priced than an ITO film based solution which requires significantly more labour costs and processing stages to produce.

Contact Diamond Coatings today to discuss your capacitive touch needs and understand how an ITO coated part can support your design considerations, as well as offering you a solution which is sustainable, proven to be completely risk averse and highly efficient throughout its lifetime.