Precautions for the use of COB ceramic substrate PCB

Precautions for the use of COB ceramic substrate PCB

COB packaging can improve light efficiency and reduce costs. LED lamp manufacturers are increasingly adopting COB ceramic substrate packaging. The precautions for the use of COB ceramic substrates are as follows:

Handling: It is forbidden to directly touch the ceramics with your hands, it will turn yellow after heating after contamination.

Storage: If it cannot be used in time after opening, store in a drying cabinet, avoid high humidity, pay attention to whether the sealing ring of the drying cabinet contains sulfur, sulfur is likely to react with ceramics, and the external electrode can be covered by film for long-term storage. Electrode yellowing.

Chips: The chips use high-efficiency long-type medium-power chips (≤0.5W), the chip layout should not be too dense, and the spacing is greater than twice the chip thickness.

Solid crystal: When solid crystal is pressed, the ceramic can be pressed with a steel plate.

Welding wire: The temperature of the welding wire is higher than the ordinary temperature, and the process parameters of the welding wire should be carefully consulted with the corresponding manufacturer. The temperature of different manufacturers will be different.

Fixture: Fixtures cannot be used similar to those used for aluminum substrates, because ceramics are hard, and aluminum substrates are tough. The fixture pressing plates must be parallel up and down, and the pressure must not be too high. Just hold it down, and feed and discharge materials. Clamp the pallet, do not clamp the ceramic directly.

Drying: Dry and dehydrate before use.

Electrode welding: When the light source is connected to the welding electrode, the solder can be melted. Do not heat the electrode for a long time, because the solder will infiltrate the silver, causing the silver to separate and damage the light source.

Thermal conductive silicone grease: The thermal conductive silicone grease on the back of the light source should not be too thick. After the coating is completed, use a plastic sheet to flatten it. The same applies to the heat sink surface. Because the thermal conductivity of thermal grease is worse than that of ceramic, too much heat cannot be transferred well.

Alumina ceramic base and aluminum nitride ceramic base circuit boards adopt laser activation metallization technology (Laser Activation Metallization, referred to as LAM technology). The bonding strength between the metal layer and the ceramic is high, the conductivity is good, and it can be welded many times. The layer thickness is adjustable within 1μm-1mm, and the maximum L/S resolution can reach 10μm, which makes it easy to directly realize the via connection.