The success or failure of high-power LED packaging is related to the development of corresponding production enterprises, which is related to its competitiveness in the LED industry. Therefore, LED packaging is a vital part of LED lamp bead manufacturers.
Then for the packaging of high-power LEDs, the way of packaging and the corresponding materials should be selected according to the LED chips . If the LED chip has been flipped, it must be packaged by flip-chip method; if it is a package integrated with multiple chips, it should consider whether the forward and reverse voltages of each chip are close, and the arrangement of LED chips and heat sink The effect of heat dissipation, efficiency of light extraction, etc. The operator should perform the actual operation based on the original design, make samples for testing, and then analyze according to the test results. This is the best result after trial and error, and finally the package solution can be determined.
In terms of the choice of heat sink materials, both copper and aluminum are the best heat sink materials from an economic point of view and a manufacturing process. However, copper and aluminum contain many alloys, and the thermal conductivity of various alloys (see Table 1) differs greatly. Therefore, when copper or aluminum is selected as the heat sink, it is necessary to look at the specific alloy composition, which is beneficial to determine the final Heat sink material.
Other materials can also be selected as heat sinks, and the effect is also good. For example, choosing silver or plating a layer of silver on copper provides better thermal conductivity. Thermally conductive ceramics and silicon carbide can also be used as heat sinks, and the effect is also very good.
Since the high-power LED generates a large amount of heat after being energized, and if the expansion coefficient of the glue and the gold wire used for the package are not the same, the expansion of the gold wire causes the gold wire to be broken or the contact resistance of the solder joint is large, thereby Affects the quality of the light emitting device. In particular, it should be noted that the encapsulant will turn yellow due to excessive temperature, thus reducing the transmittance and affecting the light output.
In general, when using high-power LEDs, consider transferring heat from the heat sink to other heat sinks. Careful consideration and necessary calculations (heat dissipation area) are also required for the selection and installation of the heat sink material. At present, the heat sink is generally also made of aluminum or copper. There are two problems to be noted here: First, the bonding material between the heat sink and the heat sink should generally be made of thermal conductive glue. If the surface of the two objects is in contact, there must be air in the middle, and the thermal conductivity of the air is very poor, so There should be a layer of thermal adhesive between the interfaces to make them in close contact, so that the thermal conductivity will be good. Second, the heat dissipation effect is related to the shape and orientation of the heat sink.
The above mainly introduces some problems that should be paid attention to during the LED packaging process. LED lamp bead manufacturers must implement LED packaging in strict accordance with industry guidelines and process flow.
