User manual 3M ANISOTROPIC CONDUCTIVE FILM ADHESIVE 7313 TECH BULLETIN

[. . . ] The user is responsible for evaluating ACF 7313 under actual conditions of use and with the substrates for the intended application that are necessary to determine whether the product is suitable for a particular application and assembly method. The reliability of any interconnection will depend upon many factors including but not limited to substrates to be bonded, plating metallurgy, bonding conditions, pitch, and circuit design. General Bonding Considerations ACF 7313 is a thermoplastic adhesive matrix randomly loaded with conductive particles. The ACF 7313 adhesive is used to join together two circuits to provide an electrical and mechanical connection. The purpose of the bonding process is to apply simultaneously heat and pressure to melt the crystalline regions of the thermoplastic thus allowing the thermoplastic to flow bringing the connecting pads into contact with the conductive particles. [. . . ] Once the film has cooled again, the carrier release liner can be removed while the adhesive remains attached to the pad location. The temperature of the tacking step should be kept below the melt temperature of the film. Tacking does not affect the shelf life of the film, and tacked parts may be stored at room temperature prior to proceeding to subsequent processing steps. Methods of tacking include: · Heating the film, for example with a hot-plate or infra-red lamp, and applying it to an unheated substrate. · Placing unheated film on a heated substrate, for example by placing the substrate on a hot-plate. · Placing unheated film on an unheated substrate and then heating both together, for example by feeding them through a heated laminator. Circuit Aligning The circuits must be brought in proper registration before bonding. This alignment step is normally performed using a camera and fixturing set-up or a microscope. Once the circuits are properly aligned they may require another tacking step to temporarily hold the assembly together. This tacking step can be performed in similar manner as the film tacking method described above. The circuits may not require this tacking step if the bonding equipment is designed to fixture the parts for both alignment and bonding operations. -2- Technical Bulletin Anisotropic Conductive Film Adhesive 7313 Bonding Process Development Thermode Bonding Constant Heat Bonder - Bond Profile Pressure Released Temperature Rise Time Bond Time Time -3- Figure 2. Temperatures shown are measured in the adhesive bond-line using a higher thermode setpoint temperature. Thermode bonding, also referred to as hot-bar bonding, involves bringing a heated thermode into controlled-pressure contact with the previously aligned circuits to be bonded. This type of bonding is typical for bonding an interconnect circuit to a printed circuit board. Thermode bonders can utilize a constant temperature thermode or a pulsed-heat thermode with micro-processor-controlled variable temperature. Figure 2 shows an example of a temperature profile measured during the process of bonding a flex circuit to a printed circuit board using a constant-temperature thermode bonder. The bonding pressure is applied immediately at the start of the bond cycle, an continues uniformly throughout the bond cycle. Care must be taken to ensure that the maximum temperature is below the temperature at which the parts to be bonded could be damaged. The bond pressure is released after the full five seconds bond time is reached. When pressure is released with the adhesive at the peak temperature, the circuits may undergo slight separation before the adhesive cools below the recrystallization temperature. Cooling under pressure is recommended for maximum mechanical and electrical performance. [. . . ] Since these factors are uniquely within the user's knowledge and control, it is essential that the user evaluate the 3M product to determine whether it is fit for a particular purpose and suitable for the user's method of application. Warranty and Limited Remedy Unless stated otherwise in 3M's product literature, packaging inserts or product packaging for individual products, 3M warrants that each 3M product meets the applicable specifications at the time 3M ships the product. Individual products may have additional or different warranties as stated on product literature, package inserts or product packages. 3M MAKES NO OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR ANY IMPLIED WARRANTY ARISING OUT OF A COURSE OF DEALING, CUSTOM OR USAGE OF TRADE. User is responsible for determining whether the 3M product is fit for a particular purpose and suitable for user's application. [. . . ]