The COB (Chip on Board) package is a technology designed to address LED heat dissipation issues. Compared to traditional through-hole and SMD (Surface Mount Device) packaging, COB offers advantages such as compact design, simplified manufacturing, and superior thermal management. This makes it an ideal choice for high-performance lighting applications where space and efficiency are critical.
In a COB package, bare LED chips are directly attached to an interconnect substrate using either conductive or non-conductive adhesive. After that, wire bonding is performed to establish electrical connections. However, if the bare chip is left exposed, it becomes vulnerable to contamination, mechanical damage, or environmental factors, which can degrade its performance or even cause failure. To protect the chip and the delicate bonding wires, they are typically encapsulated in a protective layer of epoxy or silicone. This method is often referred to as "soft encapsulation" due to its flexible and protective nature.
The COB packaging technique eliminates the need for individual mounting of LED components, making it more efficient in terms of both time and cost. It also enhances optical performance by reducing light loss and improving light uniformity. Additionally, because the chips are directly mounted onto the substrate, the overall thickness of the LED module is significantly reduced, making it suitable for slim and compact designs.
Analysis of Causes of LED Failure in COB PackagesAlthough the theoretical lifespan of an LED chip can reach up to 100,000 hours under ideal conditions, real-world performance is often limited by various factors such as packaging, driving circuits, and thermal management. In general lighting applications, the actual lifespan of LED sources or lamps may only be around 30,000 hours. In some cases, products fail within just a few months, highlighting the importance of reliability in LED design.
Common failure modes in COB-based LED products include chip failure, package failure, electrical stress, thermal stress, and assembly issues. Chip failure can occur due to overheating, voltage spikes, or material degradation. Package failure may result from poor adhesion, delamination, or moisture ingress. Electrical and thermal stress can lead to premature aging of components, while improper assembly techniques—especially when done manually—can introduce defects that reduce product longevity.
Features of COB-Based LED ProductsLED lighting systems typically consist of three main parts: the heat sink structure, the power driver, and the illumination unit. The illumination section includes the light source and secondary optical elements like lenses, reflectors, and diffusers. A typical application model is shown in Figure 1. As the core component of the system, the light source plays a crucial role in determining the overall performance of the lighting solution.
COB technology is a type of light source packaging that does not require complex surface-mount processes. Instead, it involves simply connecting the leads and electrodes to the base or housing. This simplifies the assembly process and reduces the number of components needed. However, since most COB modules are assembled manually, there is a higher risk of defects compared to fully automated production lines.
3.96mm Wire To Board Connector
3.96mm Wire To Board Connector
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