Adhesives are used in a wide range of applications in the electronics industry, from microcircuit positioning to the bonding of giant generator coils. Once the adhesive fails, the consequences are very serious, the computer will stop running, the city will be dark, or the missile will be difficult to launch.
Adhesives in the electronics industry, in addition to mechanical fixation, also require thermal conductivity, electrical conductivity, insulation, and adapt to the requirements of impact-resistant assembly, sealing and substrate protection. The characteristics required for different applications include: service life ranging from a few seconds to several years, ranging from less than micrograms to more than 1 ton.
First, the application of different types of adhesives in the electronics industry
1. Epoxy adhesive: It is the most widely used in the electronics industry because of its versatility, excellent adhesion, wide adaptability, convenient use, good electrical performance and resistance to aging.
2, organic silica gel: suitable for applications requiring flexibility, wide temperature range, high frequency, high temperature and air pollution.
3. Hot melt adhesive: hot melt adhesive can be used under the conditions of fast assembly, low strength and low working temperature.
4, acrylate adhesive: the choice of acrylate adhesive is mainly considering their excellent electrical properties, stability, good aging resistance and transparency, and can be quickly cured.
5, polyurethane glue: from low temperature to 121 ° C always keep soft, tough, firm.
6, pre-coated polyvinyl butyral: can form a tough and easy to assemble joints.
Second, the three main applications of adhesives in the field of microelectronics
1. Tube bonding;
2. The circuit component is bonded to the substrate;
3, packaging.
Another major application is printed circuit boards. Since it is necessary to withstand a soldering temperature of 250 ° C, the adhesive is limited to the bonding of the steel foil to the laminated printed wiring board.
Third, the application of adhesives in large equipment
Examples include generators, transformers, and other equipment that operate at high temperatures, as well as equipment that must operate for 20-40 years in harsh environments and high temperatures. The size of many devices eliminates the possibility of oven curing. The heat transfer of copper and other metals makes local heating impossible. Therefore, it is necessary to use a room temperature curing adhesive.
Fourth, the application of adhesives on electronic equipment
Adhesive applications can be found on almost all electronic devices, such as the bonding of radar antenna composites, providing thermal and electrical conductivity for the operation of electronic components. There is also the bonding of the missile's nose cone ring. Typical applications are:
(1) an antenna reflector for tracking/illuminating radar in a ship air defense system;
(2) The Danish Eye Snake (CobraDaYe) phased array radar system for external dielectric window and substrate bonding;
(3) Drilling various electronic components of the trident MKs (TridentMKs) missile guidance computer with a thermal conductive film;
(4) In an air traffic command radar, a cured epoxy laminate is bonded to a metal frame.
Fifth, the application of adhesive in printed circuit boards
Printed circuit boards, whether rigid or flexible, are inseparable from adhesives.
For epoxy-glass plates, acetal-phenolic, butyronitrile-phenolic or modified epoxy can be used with a maximum use temperature of about 150 °C. When used at a high temperature of 260 ° C, a glass-silicone laminate or a copper/polytetrafluoroethylene composite panel should be used.
The laminate assembly of rigid printed wiring boards can be bonded together with a plastic film coated with a thermoplastic or thermosetting adhesive.
Sometimes complicated assemblies require a thin, flexible printed circuit. At this time, the RTV silicone rubber coating can be used not only as an insulating coating but also for vibration reduction. This vibration will increase the number of welded joints. The desired fatigue load.
In addition, epoxy and silicone are applied to the stressed components to reduce the effects of shock and vibration.