After 2000, with the development of LED high-luminance and high-efficiency technology, coupled with the significant improvement of blue LED luminous efficiency, LED manufacturing costs continue to decline, so that the scope of LED applications and the willingness to adopt LED industry will continue to expand. Including LCD, home appliances, automotive and other industries, they are also actively considering the possibility of applying LEDs. For example, consumers expect high-power LEDs to achieve power saving, high brightness, long life and high color reproducibility. This represents the ability to achieve high heat dissipation and is an indispensable condition for high-power LED package substrates.
In addition, LCD panel companies are facing the EU RoHS regulations, and they need to face the environmental pressure of completely non-silvering of cold cathode lamps, which makes the market demand for high-power LEDs more urgent.
In addition to protecting the internal LED chip , the LED package also has the functions of electrical connection and heat dissipation between the LED chip and the outside.
Epoxy properties are no longer in line with high power LED requirements
One LED can reach several hundred lumens, which is basically not a big problem. The main problem is how to deal with heat dissipation? Next, after generating such a large lumen, how to maintain the stability and continuity of brightness, this is another important topic. If the heat treatment is not done well, the brightness and life of the LED will drop rapidly. For LED, how It is very important to achieve effective reliability and heat transfer.
In the past, LEDs were packaged using low thermal conductivity resins, but this is considered to be one of the causes of heat dissipation characteristics. In addition, the heat resistance of epoxy resins is relatively poor, and it may happen that the life of the LED chips themselves is not Before the arrival, the epoxy resin has been discolored, so improving heat dissipation is an important key.
In addition, not only the thermal phenomenon will change the epoxy resin, but even the short wavelength will cause problems for the epoxy resin. This is because the white LED light spectrum also contains short-wavelength light, while the epoxy resin is equivalent. It is easily damaged by short-wavelength light in white LEDs. Even low-power white LEDs can make epoxy resin damage more serious. Moreover, high-power white LEDs emit more short-wavelength light, which is more natural than low-power models. Fast, even some products have a service life of only 5,000 hours or even shorter after continuous lighting! Therefore, instead of constantly overcoming the discoloration caused by the old encapsulating epoxy resin, it is better to seek new packaging materials for the next generation.
Metal substrate into new focus
Therefore, in recent years, the use of high-heat-conducting ceramics or metal-resin packaging structures has been gradually changed to solve the problem of heat dissipation and strengthening of original features. Common methods for high-power LED chips are: large-scale chips, improved luminous efficiency, high-efficiency light-emitting packages, and high current. In this type of practice, although the amount of current illuminance will increase proportionally, the amount of heat will increase.
New technologies for high-power LED package, since the heat dissipation problem caused some troubles, cost effective in this context a metal substrate technology, after it became high efficiency LED highly concerned about another 1 development of.
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