During the last several posts, we’ve analyzed the leading factors of LED lead frames, chips and encapsulants in terms of their qualities and costs. Now, we are moving to the finale of our “high quality LED” series, the LED phosphor.
PRINCIPLES OF LED PHOSPHORS
Most LED phosphors are inorganic photoluminescent powder made of rare earth materials. Under radiance of high energy light, the electrons of the ground state absorb the energy of the exciting light and transit to the excited state of a higher-energy level. The instability of the excited state makes the electron transit back...
After analyzing LED lead frames and chips in terms of their qualities and costs, this time we will talk about another component in all LED products—the encapsulant.
LED packaging encapsulant
As we know, the chip is the core component of an LED emitter. In order to ensure the chip’s stable performance, the packaging encapsulant acts as a key role within. The function of packaging encapsulant mainly consists of three aspects: (1) Sealing. The encapsulant prevents water, sulfur and other elements from penetrating into the LED, blocking moisture as well as dust. (2) Immobilization. It mechanically fixates...
Following the last several posts where we talked about the key factors of LED lead frames in terms of their qualities and costs, today let’s move on to the core component of all LED products—the CHIP.
What is an LED chip?
An LED (light emitting diode) chip is a solid state semiconductor device. It turns electrical energy into light, making it the key component of the LED, and the most challenging part in the whole LED manufacturing process. Normally metal-organic chemical vapor deposition (MOCVD) is used to grow the LED chips. To make a LED chip,...
#1-LED LEAD FRAME
Part - 3
Material Selection 3: Design
LED lamps are directly or indirectly exposed to the air with a certain degree of moisture. Imagine there’s a poorly designed structure that is not moisture resistant enough, and the moisture penetrates into the lamp. Now that it’s been lit up for long hours and is wet, the resin falls off from the metal substrate, pulls apart the welded wires and eventually cuts the connected circuit. A deficient design may restrict the fields, places, and conditions of product usage. That’s why LED designers and manufacturers have...
#1-LED LEAD FRAME
Part - 2
Material Selection 2: Synthetic Resin
At present, PPA, PCT and EMC are among the most commonly used materials. PPA and PCT are thermalsoftening1 plastics, while EMC (mainly made from of epoxy) is thermosetting2. EMC ranks first in temperature tolerance among the three. PPA offers inferior properties compared to the other two in temperature tolerance, yellowing resistance and air-tightness, yet it has the most appealing price.
Due to different abilities to dissipate heat, these three materials are applied for different specifications. PPA is used for 0.1-0.2W LED lights,...