COB Packaging Frequency
The frequency characteristics of COB packaging applications vary significantly depending on the application scenario. The core related indicators are concentrated in three dimensions: refresh rate, operating frequency, and RF bandwidth.
1. Display Field: Refresh Rate and Gray-Scale Refresh Frequency Dominate Performance
In COB-packaged LED displays, refresh rates cover the range of 1920Hz-7680Hz, with high-end products achieving an ultra-high refresh rate of 7680Hz, where flicker is imperceptible to the human eye. Simultaneously achieving 14-bit-16-bit high gray-scale levels requires a refresh frequency of several thousand Hz to ensure accurate color transitions for over 16.77 million colors.
2. Integrated Circuits: Operating Frequency Breaks the 5GHz Physical Limit
CPU/GPU modules using Flip-Cob technology shorten signal transmission distances to the 50μm level through gold bump interconnects. Combined with a low-dielectric-constant substrate, operating frequencies can reach 3.5GHz-5.2GHz. Real-world testing data from a supercomputing laboratory shows that COB-packaged AI chips using ceramic substrates maintain a stable frequency of 5.06GHz under liquid cooling conditions.
3. RF Applications: 60GHz Millimeter-Wave Band Capability
In 5G millimeter-wave module packaging, COB technology, through heterogeneous integration of gallium arsenide and gallium nitride chips, achieves an error vector amplitude (EVM) better than -32dB in the FR2 band (24.25GHz-52.6GHz). Satellite communication modules have further broken through to the Q-band (40GHz-60GHz), with transmission loss controlled within 0.15dB/mm.
4. Three Key Elements of High-Frequency Optimization
• Substrate Dielectric Loss: Rogers RO3003 (Dk=3.0) or aluminum nitride substrate (Dk=8.6) are preferred for high-frequency circuits.
• Micro-pitch Soldering: 20μm pad spacing combined with laser-assisted mounting reduces parasitic inductance to below 0.05nH.
• Electromagnetic Shielding: A three-dimensional fence-like grounding structure reduces electromagnetic radiation by 15dB.
In practical applications of 8K ultra-high-definition broadcast vans, COB-packaged displays, combined with a 3840Hz refresh rate, successfully eliminated the scanline effect of 4K/120p high-speed cameras. This verifies the deep coupling characteristics between high-frequency parameters and the terminal scene.
