are registered trademarks and the Cree logo is a trademark
of Cree, Inc. Other trademarks, product, and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. This
document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com. For warranty information,
please contact Cree Sales at sales@cree.com.
2
XLamp
®
LED ChEmiCaL CompatibiLity
•
•
Procedures and test processes for measuring and assessing potential chemical interactions
Chemical incompatibility test results
EXampLEs of ChEmiCaL inCompaTibiLiTy
This section contains multiple examples of real-life discoloration caused by vOCs. Figures 3 and 4 show a luminaire based on six XLamp
Xr-e LeDs. Figure 3 shows the light output at initial turn-on and Figure 4 shows the same luminaire after less than 100 hours of operation.
Figure 4 shows significant yellowing of the light output, which is likely caused by a color shift in the LEDs. It is worth noting the space
have caused this discoloration of the surface of the LeDs.
Your Customer Has Developed a Great
plate is a nearly sealed microenvironment. The most likely explanation is that vOCs
LED Fixture.
But wait …. What Has Happened?
between the circuit board and the external optical
figure 3: XLamp Xr-E LED-based luminaire at initial illumination
figure 4: XLamp Xr-E LED-based luminaire, yellowed after 100 hours
From left to right in Figure 5 is a pictorial representation of a silicone polymer as vOCs are introduced that occupy the free spaces in the
silicone. After exposure to heat and high photonic energy, this introduction results in vOC-based discoloration.
are registered trademarks and the Cree logo is a trademark
of Cree, Inc. Other trademarks, product, and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. This
document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com. For warranty information,
please contact Cree Sales at sales@cree.com.
3
Appearance of Normal and Discolored LEDs
XLamp
®
LED ChEmiCaL CompatibiLity
figure 6: Examples of normal (left) and voC degraded LED (right)
The photograph on the left in Figure 6 is the normal appearance of a Cree XLamp LeD. On the right, the same type of XLamp LeD chip has
a pronounced brown discoloration due to exposure to vOCs while in operation with high photonic power output at nominal environmental
temperatures. This discoloration of the encapsulants is on the top of the LeD chip, localized to the area just above the chip surface,
closest to the source of heat and high photon energy. note that discoloration can occur at various points in an LeD’s lifetime; factors that
affect discoloration of vOCs include heat, photonic energy and wavelength. Figure 7 shows several examples of the effects of chemical
incompatibility in the LeDs.
Cree Confidential
Examples of chemical incompatibility with XP
figure 7: a variety of XLamp LEDs showing chemical incompatibility
vOC-based discoloration can occur as a result of outgassing of solid materials. The sequence of pictures in Figure 8 documents just such
a case of chemical incompatibility. Cree investigated the source of LeD discoloration and, even though the LeDs were not in a sealed
environment, an LeD on the luminaire discolored, as shown in the upper left photograph.
are registered trademarks and the Cree logo is a trademark
of Cree, Inc. Other trademarks, product, and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. This
document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com. For warranty information,
please contact Cree Sales at sales@cree.com.
4
XLamp
®
LED ChEmiCaL CompatibiLity
Materials Used in SSL Luminaires Can Have a Negative Impact
Materials Used in SSL Luminaires Can Have a Negative Impact
figure 8: sequence of voC investigation
Cree Confidential
The root cause of the problem was revealed as the disassembled unit sat overnight on a white piece of paper. The next day, indication of
outgassing from the small gaskets was evident on the paper, as shown in Figure 9. The gasket material, in close contact with the LeD lens,
offered a source of vOCs, which ultimately led to the LeD’s discoloration. This case demonstrates the importance of testing all chemicals
and materials in the specific application and environment for which they are intended to be used.
Cree Confidential
figure 9: Evidence of voC outgassing from an o-ring
are registered trademarks and the Cree logo is a trademark
of Cree, Inc. Other trademarks, product, and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. This
document is provided for informational purposes only and is not a warranty or a specification. For product specifications, please see the data sheets available at www.cree.com. For warranty information,
市调机构SEMI认为，2021年将是全球晶圆厂标志性的一年，设备支出增长率可望来到24%，达到677亿美元的历史新高，比先前预测的657亿美元再高出10%，所有细分市场产品都将出现强劲成长... 据国际半导体产业协会(SEMI)公布2020年第二季更新版《全球晶圆厂预测报告(World Fab Forecast)》显示，2021年是全球晶圆厂设备支出的标志性一年，增长率为24％，达到创...[详细]
stm32/stm8
