Electrically conductive adhesives are now commonplace and have contributed immensely to the micro design of everyday consumer electronic devices such as iPads, mobile phones, medical devices, flexible PCB’s, wearable conductive clothing, RFID tagging and RFI shielding etc.
There are two types of electrically conductive adhesives: isotropic and anisotropic. Isotropic conductive adhesives (ICA) are electrically conductive in all directions. They are used in applications such as chip contacting and bonding electrically conductive SMDs.
Anisotropic conductive adhesives (ACA) contain special conductive particles in the µm range, which conduct electricity in one direction only. These adhesives are used, for example, in many sensitive structures on circuit boards, such as LCD connections or contacting flexible PCBs, or for bonding antenna structures on RFIDs.
Today of course, the range of conductive adhesives and their applications is vast and varied. Conductive adhesives are tailored to suit almost any application and are formulated as either one component products that are thermally curable or two component products that when mixed together cure at room temperature or for a faster cure time they can be thermally cured. When selecting the right adhesive for your specific project it is important to consider the following points and discuss them in depth with one of Eurobond’s specialist adhesive technical advisers.
- The type of dispensing method will you employ ie, syringe, stamp, screen print or jet?
- The type of filler you need ie Silver, Copper or Graphite?
- Do you require a paste or a liquid adhesive one or two component product?
- Do you need an Isotropic or Anisotropic adhesive?
- What pot life best suits your particular application?
- What cure time and cure method will you employ?
- What volume resistance do you require?
- What coefficient of thermal expansion can your project accommodate.
Eurobond Adhesives offer the Elecolit® range of silver filled, one-component adhesives that can be simply applied with dispensers, jets or screen-printed, as well as two-component products that cure at room temperature and have a long pot and storage life.
Innovative hardener systems in many of the one part epoxy based adhesives develop ‘cure’ within minutes and these can be used to connect heat sensitive components to printed circuit boards, wave guide plumbing, hybrid circuit assembly, connecting ground wires to components, making conductive tracks or pathways and bonding discrete devices and hybrid circuits. Other applications include bonding conductive paths in heated car windscreens and mirrors, RFID applications, bonding batteries to foil/film, bonding flexible film LCD’s to hard FR4 boards, circuit track repairs, populating PCB’s, the list is almost endless.
Eurobond Adhesives offer a select range of one and two component electrically conductive adhesives.
Elecolit® 325 is a two component pure silver filled epoxy adhesive which combines the excellent adhesive properties of the epoxy with the electrical conductivity of pure silver. It is easy to use because equal amounts of Part A and B (resin and hardener) are mixed together and it has a 1 to 2 hour pot life. Elecolit® 325 may be processed with dispensers, stamps or by screen printing. Curing occurs at room temperature. Increasing the temperature speeds up the curing process. Elecolit 325 has excellent gap fill properties too.
Applications
- Connecting heat sensitive components to printed circuit boards.
- Bonding wave guide plumbing, hybrid circuit assembly.
- Replace metal solder where temperature or convenience in the application is required.
- Chip bonding for discrete devices and hybrid circuits.
Elecolit® 414 is a polyester – based, electrically conductive ink, coating and adhesive suitable for application by stamping, screen printing, dipping and syringe dispensing. Elecolit® 414 is formulated to provide exceptional conductivity when cured at low temperatures. Unlike conventional conductive materials, this product is very resistant to flexing and creasing. Some applications for Elecolit® 414 include, but are not limited to, EMI/RFI shielding of polyimide flexible circuits, polymer thick film circuitry, membrane switches, electrical attachments for surface mounted devices and anode coatings for tantalum capacitors.
Elecolit® 3653 is a silver filled, highly flexible solvent free conductive adhesive. The flexibility of the cured adhesive makes it ideally suited for applications which involve vibration or thermal shock. The product can be dispensed or processed with stamp, print or screen print. Elecolit® 3653 is a one component product, thermally curable in short time frames.
Elecolit® 342 is a 1K silver-filled electro conductive coating with excellent glass, metal and plastics bonding properties, which cures to a hard film in the air. It can be processed with brushes, dispensers or via needle transfer. Electrical conductivity is excellent. Elecolit® 342 has excellent glass bonding properties and is, for example, being used to create windshield defroster contacts in cars, or RFI shielding of electronic housings. After extended storage periods, the product must be re-homogenized as it sediments naturally in low viscosity resins.
For more information or to discuss your particular bonding application please contact our expert technical team.
+44 (0)1795 427888.
