Recently, the National Standards Commission of China solicited public comments on 285 proposed national standard projects, with a comment deadline of August 6, 2023. The list includes six lighting-related national standard projects concerning test methods for rare-earth phosphors used in LEDs, such as "LED phosphor test methods Part 1: Determination of spectral performance" and "Part 2: Determination of relative brightness." The China Lighting Association compiled these lighting-related national standard projects into a collection for reference.
Part 1: Determination of Spectral Performance
Replaces standard number: GB/T 23595.1-2009
Replaced standard title: Test methods for rare-earth yellow phosphors for white-light LEDs Part 1: Determination of spectral performance
Key technical content:
- Modified the scope of application, extending the phosphor excitation wavelength range compared with Part 1 of the 2009 edition.
- Added two normative references.
- Added three terms and definitions.
- Revised instrument technical requirements: the wavelength accuracy of the fluorescence spectrophotometer was changed from ±0.5 nm to ±0.3 nm.
- Changed wording for excitation and emission peak wavelengths: "excitation spectrum peak wavelength" and "emission spectrum main peak wavelength" were revised to "excitation peak wavelength" and "emission peak wavelength."
- Adjusted precision parameters: narrowed repeatability limits and allowable errors for excitation peak wavelength and emission peak wavelength.
- Added test report requirements (see Clause 9).
Part 2: Determination of Relative Brightness
Replaces standard number: GB/T 23595.2-2009
Replaced standard title: Test methods for rare-earth yellow phosphors for white-light LEDs Part 2: Determination of relative brightness
Key technical content:
- Modified the excitation source range from 440 nm–480 nm to 350 nm–480 nm.
- Added two normative references.
- Added three terms and definitions.
- Added five standard reference powders.
- Replaced the test instrument with a spectrometer.
- Revised test environment requirements.
- Removed references to "barium sulfate," "barium sulfate plate," and procedures such as "adjust the calibration button, read zero, then illuminate with excitation light" and "adjust the calibration button."
- Added test sample coding and corrected repeatability limit values.
Part 3: Determination of Chromaticity Coordinates
Replaces standard number: GB/T 23595.3-2009
Replaced standard title: Test methods for rare-earth yellow phosphors for white-light LEDs Part 3: Determination of chromaticity coordinates
Key technical content:
- Modified the excitation source range from 440 nm–480 nm to 350 nm–480 nm.
- Added two normative references.
- Added three terms and definitions, and revised the CIE standard chromaticity reference to CIE-1931.
- Revised instrument technical requirements: wavelength accuracy from ±0.5 nm to ±0.3 nm; chromaticity coordinate accuracy from ±0.002 to ±0.0015.
- Replaced the test instrument with a spectrometer.
- Added a description of the photodetector.
- Revised test environment requirements.
- Added test sample coding and corrected repeatability limit values.
- Revised allowable error from 0.005 to 0.003.
Part 4: Determination of High-Temperature, High-Humidity Performance
Replaces standard number: GB/T 23595.4-2009
Replaced standard title: Test methods for rare-earth yellow phosphors for white-light LEDs Part 4: Determination of high-temperature, high-humidity performance
Key technical content:
- Modified the scope of application, extended the phosphor excitation wavelength range, and added humidity testing.
- Added two normative references.
- Added three terms and definitions.
- Revised the test principle: the test condition was changed from a temperature test at 180°C to a temperature-humidity test at 85°C and 85% relative humidity.
- Revised instruments and apparatus: added a constant temperature and humidity test oven; removed the weighing bottle; replaced the desiccator with a petri dish; revised the technical requirements for the relative brightness tester, changing the excitation source wavelength from 460 nm to 400–460 nm.
- Revised the measurement procedure.
- Revised the expression of test results.
- Revised precision requirements.
- Added test report requirements.
Note: This standard specifies setting the temperature and relative humidity of the constant temperature and humidity test oven to 85±1 °C and 85±2%, respectively. When the set values are reached, place phosphor samples in the oven and store for 1000 h, then remove and naturally cool to room temperature in a desiccator. Measure relative brightness, chromaticity coordinates, or other relevant properties for treated and untreated samples; the changes between them indicate the high-temperature, high-humidity stability of the phosphor under test.
Part 7: Determination of Thermal Quenching Performance
Replaces standard number: GB/T 23595.7-2009
Replaced standard title: Test methods for rare-earth yellow phosphors for white-light LEDs Part 7: Determination of thermal quenching performance
Key technical content:
- Modified the excitation source range from 440 nm–480 nm to 350 nm–480 nm.
- Added two normative references.
- Added three terms and definitions, and revised the CIE standard chromaticity reference to CIE-1931.
- Revised the instrument name from "thermal quenching analysis system" to "phosphor excitation spectrum and thermal quenching analysis system."
- Revised instrument technical requirements: the previous precision specification of ±1.5% was changed to a temperature control accuracy of ±2°C.
- Revised formula (1): the numerator result is changed to an absolute value.
- Removed the previous allowable differences for thermal quenching of chromaticity coordinates and relative brightness.
- Added a requirement on repeatability under repeatability conditions: the absolute difference between two independent test results must not exceed the repeatability limit (r) within the specified average value range; cases exceeding r must not exceed 5%. The repeatability limit (r) is obtained by linear interpolation using the values in Table 1.
- Added test sample coding and corrected repeatability limit values.
- Revised allowable error from 5.00% to 2.00%.
Part 8: Determination of High-Pressure Accelerated Aging Life
Key technical content:
This standard specifies the test method for high-pressure accelerated aging life of rare-earth phosphors for LEDs excited by ultraviolet to blue light with wavelengths from 350 nm to 480 nm. It applies to the determination of high-pressure accelerated aging life for such phosphors. Test principle: set the temperature, relative humidity, and internal pressure of the high-pressure accelerated aging test chamber to specified values. When the set values are reached, place phosphor samples in the chamber and store for the specified time, then remove and naturally cool to room temperature in a desiccator. Measure relative brightness, chromaticity coordinates, or other relevant properties for untreated and high-pressure accelerated-aged samples; the absolute differences between them indicate the high-pressure accelerated aging life of the phosphor under test.
