The hidden bond that makes all the difference
What are the main trends in adhesives and what are the issues of which to be aware? A key requirement these days is for rapid assembly. Design engineers wanting to satisfy increasingly tight 'nip and tuck' product cycles are looking for adhesives that offer both quality and cost efficiency. Individual processes need to be integrated into the in-line production as early in the product manufacturing chain as possible. One option is light-curing adhesives, which cure by UV or visible light in seconds. Also, since light cure adhesives do not require heat curing, this makes them ideal for bonding temperature-sensitive plastics or use close to sensitive components in the areas of PCB, microelectronics assembly, wire tacking, potting and encapsulating. Aesthetics, coupled with the consumer 'feel-good' factor, has seen growth in the use of various metal and plastic parts in the design of electronics devices. Such a mix of materials with different thermal expansions do not necessarily react in the same way to temperatures and shock, putting yet more stress on bonded joints. Here thermo-bonding film is often ideal, as it meets the strength of bonding required, whilst being easy to adopt for high-volume, low cost manufacturing. Using thermo-bonding also removes the need for screws, making products more attractive and stream-lined. Another benefit can be impairing users' ability to enter the device by removing screws, or 'tamper -proofing'. Additionally, there are films on the market that can be cured at increasingly low temperatures. This is important in environments where additional heat cannot be used to assemble products, or for installation outdoors. On 1 July 2006, the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment Regulations 2006 came into force. These restrict the use of lead, cadmium, mercury, hexavalent chromium, PBE and PBDE in all electronic and electrical equipment covered by the regulations. In turn, this impacts on many of the adhesives that companies have become accustomed to and therefore they need to seek more environmentally-friendly alternatives. Another trend in adhesives is towards products that perform more than one function. Adhesives and tapes can provide shielding against electromagnetic interference (EMI) - an increasing issue in small form products that emit various kinds of radio signals - or provide thermal heat transfer performance for higher powered devices, creating need for more heat dissipation away from active components, not just bonding.
