More LED information, please click Real Green Lighting Company Limited
LED chip is the most important raw material, its quality directly determines the LED performance. Especially high-end LED lighting for automotive or solid state, absolutely no tolerance for defects, that the reliability of such equipment must be very high. However, LED chip packaging factory incoming inspection due to lack of experience and equipment, the chip does not usually perform incoming inspection, after the failure of the chip available, often only eat Yaba Kui. Jin Jian detecting accumulated a large LED failure analysis case based on the introduction of LED chips incoming inspection services, through the use of high-end analytical instruments to identify strengths and weaknesses of the chip. The testing services can complement LED packaging factory / chip proxy factory incoming inspection, to prevent defective chip storage, chip avoid quality problems caused by the loss of the whole lamp beads.
Test items:
First, the performance parameters of the test chip
Wd (dominant wavelength), Iv (brightness), Vf (forward voltage), Ir (leakage), ESD (antistatic ability) and other optoelectronic performance test chip, Jin Jian as a third party testing agencies to identify the supplier offerings whether the data standards.
Second, the chip defect Find
Test content:
1. Measure the chip, the chip size and the size of the electrode meets the requirements, the electrode pattern is complete.
2. Does the presence of the chip solder contamination, damaged joints, damaged grains, grain sizes cutting, cutting tilt grain and other defects.
LED chip LED damage will directly lead to failure, thus improving the reliability critical to the LED chip. Evaporation process is sometimes required spring clip fixed chip, it will produce clip marks. If the job is not fully developed yellow mask and will have holes in the light emitting area of more residual metal. Grains FEOL in the system Cheng Ruqing washing, evaporation, yellow, chemical etching, fusing, grinding and other operations must use forceps and flower baskets, vehicles, etc., so the situation will die electrode scratching occurs.
Influence of electrode pads of the chip: the chip electrode deposition itself is not solid, resulting in loss or injury after the wire electrode; electrode chip itself poor solderability, solder balls can cause Weld; improper storage can cause the chip electrode surface oxidation, surface contamination etc., minor contamination bonding surface may affect the diffusion of metal atoms between the two, resulting in failure or Weld.
3. The chip defect epitaxial region search
LED epitaxial wafer in a high Wenchang Jing process, the substrate, MOCVD reaction chamber residual sediments, ambient gas and Mo sources will introduce impurities which will penetrate the epitaxial layer to prevent the gallium nitride crystal nucleation, formation of various all sorts of epitaxial defects in the epitaxial layer surface eventually form tiny holes, which will seriously affect the quality and performance of the crystal wafer thin film materials. Jin Jian developed a detection method to detect the rapid identification chip epitaxial defect region, at low cost and quickly detect the chip 80 percent of the epitaxial layer epitaxial defect, to help customers choose the high quality LED epitaxial wafers, chip.
4. The chip technology and observe cleanliness
Electrode process is the production of LED chip key processes, including cleaning, deposition, yellow, chemical etching, fusing, grinding, will be exposed to a lot of chemical cleaning agents, if the chip is not clean enough to clean, make the harmful chemical residues. These harmful chemicals in the LED is energized, and the electrode electrochemical reaction, resulting in dead lights, light, dark, bright, black and other phenomena. Therefore, the identification chip chemical residues is critical for LED packaging factory.
Case (a):
A customer red lamp dark light beads found the problem, but no cause has been entrusted Jin Jian analysis of the cause of failure. After a series of instrumental analysis Jin Jian exclude packaging reasons, bare die suppliers for testing, found that the light-emitting region of each chip has an area ranging from pollutants, energy spectrum analysis showed that the pollutants contained C, O two elements, indicating that organic pollutants. We recommend that customers pay attention to the chip manufacturers in production process specifications and workshop environment assessment, and strengthen incoming inspection of chips.
Case (b):
A customer produced a number of lamp beads appear leakage problems, commissioned Jin Jian find out why. Jin Jian by scanning electron microscopy to identify the reasons for the leakage of these lamp beads electrostatic breakdown, and bare die suppliers testing and found the chip surface of epitaxial layer has a large number of black holes, these defects show poor crystal quality epitaxial layers, PN junction internal defects. Empty find help customers define the responsibility of the party responsible for the accident, for customers to recoup their losses.
NOTE: LED chip manufacturing process
LED chip manufacturing process flow diagram
Wafer cleaning → → → plating transparent electrode layer is a transparent electrode pattern photolithographic etching → → → ashing platform graphics photolithography → → dry etching, ashing → → annealing → SiO2 deposition window graphics lithographic etching → → SiO2 ashing → N pole graphics lithographic pre-cleaning → → → coating peeling → annealing → P extremely graphic lithographic coating → → → stripping → cutting → polishing chip → product testing.
Grown into a wafer, the next step began to make LED epitaxial wafers electrode (P pole, N pole), and then they began to use laser or diamond knife cutting LED epitaxial wafers, chip manufactured after, and then on the wafer nine different positions extraction point do parametric testing. This is mainly voltage, wavelength, brightness testing, in line with normal standard parameters wafer shipments continue to the next step, do not meet the requirements, put aside dealt with separately. After the wafer is cut into chips, you need a 100% visual inspection (VI / VC), the operator must be in multiples of 30 visually at a magnification of the microscope. Then using automatic machine classification according to the different voltages, wavelength, brightness prediction parameters for fully automated chip selection, testing and classification. Finally, the LED chip to be checked (VC) and labeling. Chip type, batch number, quantity and optical measurement statistics recorded on the label attached to the back of glossy paper. Blue film chip will make the final mesh detection test, a visual inspection of the same standard with the first, to ensure that chips neatly arranged and quality standards. This is the LED chip manufacturing process.
No comments:
Post a Comment