Redefining the make and use of Anisotropic Conductive Films for hybrid and flexible electronics.

L. Morten
CondAlign AS,
Norway

Keywords: ACF, Hybrid and flexible electronics, electrical conductivity

Summary:

Since 2010, CondAlign AS has developed a technology for creating anisotropic conductivity in polymer films, based on dielectrophoresis. The technology can be used to produce a range of anisotropic conductive films (ACFs) with different material properties such as flexibility, adhesiveness and transparency. The technology uses an electric field to structure and align particles in a liquid polymer matrix. The matrix is then cured, locking the particles into their aligned positions resulting in an ACF. The particle types and amount impact the conductive properties of the film, for instance whether electrical or thermal conductivity is realized. This particle alignment permits a tenfold reduction or more of particle content compared to traditional conductive films, leading to reduced cost as well as enabling the final product to retain most of its initial material properties, like softness, adhesiveness and transparency. The technology itself is material independent and can target a broad range of applications. This represents a huge advantage and allows fulfilling the requirements of the application. The conductivity and other film properties are tuned by the selection of conductive particles, matrix material and process parameters. Film thicknesses from less than 10µm up to 1mm and more are demonstrated. Three specific application examples: 1. ACFs in the form of PSAs, for bonding components at room temperature, for instance in flexible and hybrid electronics, providing mechanical and electrical connection. Thus, a pressure sensitive adhesive (double-sided-tape) with anisotropic conductivity. No additional heat and only firm pressure is required to achieve mechanical and electrical connection. It is thus insulating in the x-y-plane, and conductive in the z-direction (through plane). Pitch (distance between two conductive chains) down to 8µm has been realized at film thicknesses between 10 and 15µm. With this adhesive ACF, components (COG) with contact areas as small as 20 by 20µm have been mounted. Moderate pitch (ca 50 µm) material is for instance well suited for bonding flex tails on boards (FOB) and related bonding situations in flexible and hybrid electronics. 2. Heat conductive films for use as thermal interface materials, enhancing efficient heat transfer away from crucial components in electronics. Due to the reduced particle amount the material retains most of the initial properties and can have superior wettability, enabling miniaturization and improving performance and reliability in electronics hardware. 3. Skin friendly anisotropic PSA film materials for ECG-electrodes and skin patch applications. These cost-efficient, dry electrodes without hydrogel can reduce the skin irritation and allow for reduced packaging, longer shelf life and longer patient usage. CondAlign’s business model is based on licensing, and well scalable. The licensee will produce the material for their applications and pay royalty to CondAlign based on production and/or sales volumes. CondAlign develops materials from lab-scale to pilot production together with customers, and provides all technical services that enables a short time to market, like R&D, lab-work, product development, industrialization and pilot production CondAlign signed its first license agreement in 2017 and commercial incomes are increasing.