Light emitting diodes are light emitting dies that get their color or hue through the phosphor that is coated on top of the die. They are typically blue tinted and are getting their color from a combination of the phosphor, the die light intensity and the overmolded optoelectronic molding compound. There are multipl LED types for a huge variety of applications, ranging from simple through hole mono chrom LEDs to backlight, organic, miniLEDs and industrial baylights. All of these LED types have the same principle but completely different application and reliability requirements.
Application requirements
RGB SMT Display Applications:
- Junction temperature is low; Packages are 0.2W – 0.5W; 20mA current
- Contrast is more important than brightness (hence the black body)
- Silicone is not used as it is clear molding compound application
Mid Power White LED Applications:
- Junction temperature is 85°C-125°C; Package: 0.1W – 0.5W;
- Replaces more expensive alternative (silicone) as encapsulant
- Stability against heat & UV
- Highest transmittance in visible & IR wavelengths; Earliest transmittance onset (280 nm)
Other Considerations --- Indoor vs Outdoor Application
- Indoor uses diffusant while outdoor uses a low reflectivity (reduce glare)
- Indoor Packages: 1010,2121,3528; Outdoor Packages: 3535 & 5050
- Outdoor requires UV resistance & low moisture absorption
- Outdoor applications must pass these tests:
- 85°C /85%RH + 3x 260°C reflow
- Thermal Cycle tests: -65°C to 150°C for 200 cycles
LED Product overview
| | Monochrome LEDs | HD RGB LEDs | White LEDs |
Product | TC-8020 (Star Product) | TC-8040 | TC-7600 (Popular Product) | TC-7800 (In Development) | TC-8030 | TC-8060 (Popular Product) | TC-8090 (In Development) |
Summary | Good adhesion to BT substrate/metal leadframe Adequate flexural modulus/strength Excellent anti-reflow performance. Good processability and moldability | Great moisture resistance property Enable LED display pass hash durability tests Ensures uniform colours and uniform emitting light at large angles Reduce warpage | Excellent anti-yellowish performance at high temperature Reduced light decline by blue/white light Excellent adhesion to Ag/Cu and PCB substrate Good moldability and higher reliability Two optional forms: cylindrical tablets, and fine powder |
Applications | 7-segment LED display, compact LED indicator, monochrome Chip LED, photo-link | High density (fine-pitch) RGB LED display | Decorative White LED | Backlight | High Reliability Backlight |
Light Decline Aging Test | - | Medium 10-50% RT*20mA*500hrs | Medium 10-50% RT*5mA*1000hrs | Low <50% RT*20mA*500hrs | High <10% RT*5mA*1000hrs |
Reliability Tests | Reflow, TCT, 85℃@85%RH | Reflow, TCT, 85℃@85%RH, PCT | Reflow, TCT, 85℃@85%RH |
Highlight | | High reliability Mid blue-ray decay | | Low blue-ray decay High anti-yellowish | | | Low blue-ray decay Anti-moisture |
Die attach for leadframe LEDs
Conductive
Non Conductive
