As the base material of the lamp bead, the LED bracket is an important material for the LED lamp bead, and it is the carrier of the LED chip. The bracket is responsible for heat dissipation and conductivity, the thermal resistance of the lamp bead, and the initial defect rate. Many SMD disconnections are caused by design defects and quality defects of the LED bracket.
There are different lamp bead types according to different applications, which are actually different LED types caused by different LED bracket types. The specific classifications are: in-line bracket, patch bracket, high-power bracket, flat bracket and COB bracket. The LED bracket needs to be electrically and thermally conductive, so metal is used as the base material. At the same time, some areas need to be insulated, which requires engineering plastics.
Therefore, the general LED bracket is formed by metal stamping and then injection molding. As a light-emitting diode, LED needs to be electroplated on the inner surface of the metal, and silver is a good light reflecting material, so the general LED is electroplated silver surface treatment. The bracket materials used by different power LEDs are different. Low power generally uses PPA, medium power generally uses PCT, and currently some high power uses EMC materials. All plastic materials have water absorption, so in the LED lamp bead production process, the bracket needs to be baked and dehumidified. The treatment of the plating layer is the key point of the bracket. The thickness and quality of the plating layer are related to the subsequent luminous flux and welding performance.
In fact, the first condition for choosing a good LED is to choose a good bracket. At present, there are some parts on the market that are formed by stamping, re-plating, and injection molding with iron substrates, which are of relatively poor quality. It is better to use copper for medium power. The electroplating layer needs to be controlled at about 80U". However, many manufacturers currently only require electroplating to 40U". The welding of the thin plated bracket must be controlled, which is easy to cause false weld. Nowadays, most of the high-power brackets use ceramic substrates.
If it is a ceramic material, it is necessary to understand the key points of the ceramic composition and coating. The high-power COB lamp beads appearing on the market are generally formed by electroplating on copper plates and then injection molded. CITIZEN’s COB lamp bead holders are formed by pressing aluminum materials. Of course, the selection of CITIZEN’s aluminum materials is subject to certain conditions. The PCB material is the BT board material used, and the adhesive in the middle is critical. So the key to doing a good job is how to do it and how to choose materials. This is the most important thing.
