Anisotropic conductive film (ACF), is a lead-free and environmentally friendly adhesive interconnect system that is commonly used in liquid crystal display manufacturing to make the electrical and mechanical connections from the driver electronics to the glass substrates of the LCD. The material is also available in a paste form referred to as anisotropic conductive paste (ACP), and both are grouped together as anisotropic conductive adhesives (ACAs). ACAs have more recently been used to perform the flex-to-board or flex-to-flex connections used in handheld electronic devices such as mobile phones, MP3 players, or in the assembly of CMOS camera modules.
ACF continues to be the most popular form factor for ACAs, largely due to the ability to precisely control the volume of material, density of the particles in any sample, and the distribution of those particles within the sample. This is particularly true in the traditional ACF stronghold of display interconnects, but ACF has also seen strong growth out of the display industry and into areas long dominated by surface-mount technologies. The ability to make interconnections in a very small XYZ space has been the key driver in this expansion, helped by the ability under certain conditions to greatly lower cost either by the reduction of component counts or total material used.
ACPs are widely used in lower-end applications, primarily in the assembly of chips on to RFID antenna substrates. They are also used in some board or flex assembly applications, but at a much lower level than ACFs. While ACPs are generally lower cost than ACFs, they cannot provide the same level of control in adhesive quantity and particle dispersion as ACF. For this reason it is very difficult to use them for high-density applications.