AUTOMOTIVE SnapLED Xtreme Assembly and handling information Introduction This application brief covers recommended assembly and handling procedures for SnapLED Xtreme. SnapLED Xtreme emitters leverage the time-tested reliability and robustness of the SnapLED package. The innovative lens shape demonstrates Lumileds determination to enable our customers to achieve styling differentiation at affordable system cost. Proper assembly, handling, and thermal management, as outlined in this Application Brief, ensures high optical output and long LED lumen maintenance for SnapLED Xtreme. Scope The assembly and handling guidelines in this Application Brief apply to the following products: SnapLED XTREME 300mA (A1SX-O612B13) AB125 SnapLED Xtreme Application Brief 2015 Lumileds Holding B.V. All rights reserved.
Table of Contents Introduction... 1 Scope.... 1 1. Component... 3 1.1 Reference Document...3 1.2 Description...3 2. Optical Management... 3 2.1 Optical Center...3 2.2. Focal Point and Intensity Distribution....4 2.3. Illuminance Distribution...6 2.4. Optical Application Examples....8 2.4.1. Optical Reference Design 1: Direct Lit Diffuser...9 2.4.2. Optical Reference Design 2: Direct Lit Double Diffuser...10 2.4.3. Optical Reference Design 3: White Box....11 2.4.4. Optical Reference Design 4: Fresnel Lens with Spreading Optic...12 2.4.5. Optical Reference Design 5: Pillow Mirror...13 3. Thermal Management... 14 3.1. Thermal Management and Clinch Frame Area...14 4. Assembly Process Recommendations and Parameters... 15 4.1. Mechanical Files...15 4.2. Pick and Place Nozzle...15 4.3. Handling Precautions...16 5. JEDEC Moisture Sensitivity Level.... 16 About Lumileds... 17 AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 2
1. Component 1.1 Reference Document The SnapLED Xtreme Datasheet DS125 is available from the Lumileds website at lumileds.com. 1.2 Description As with all SnapLEDs, the SnapLED Xtreme LED package is cold-clinched onto a tinned-copper sheet (a.k.a. clinchframe ) which serves as a robust mechanical, thermal and electrical connection. SnapLED Xtreme consists of a VTF die mounted onto a nickel plated copper lead frame. The copper lead frame provides mechanical support and thermally connects the LED chip to the clinch frame. Figure 1. Electrical and thermal connection. The die is mounted onto the anode side. As a result, most of the heat from the die will be conducted to the clinch frame via the anode side. The N top side of the LED is connected with the Cathode side via a gold wire. The LED is casted with high performance, proprietary EPOXY. The EPOXY lens shields the chip from the harsh, automotive environment and distributes the light. The unique lens shape of SnapLED Xtreme enables a homogeneous distribution of the light over a planar, rectangular surface. This is in bright contrast to a conventional LED with a Lambertian radiation pattern, which requires secondary optics to achieve a similar homogenious projection. 2. Optical Management 2.1 Optical Center SnapLED Xtreme has a unique EPOXY lens (primary optic) shape. SLX provides a uniform illuminance pattern at a plane parallel to the clinch frame. The target range of illumination is rectangular. The size of the illuminated area is dependent on the distance from the secondary optic to clinch frame. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 3
Figure 2. SLX with illuminance at 20mm from lens base. The coordinate system of optical data is: a. origin: planar center of lens base surface on package b. z-axis: optical axis c. x-axis: along clinch leads d. y-axis perpendicular to clinch leads 2.2. Focal Point and Intensity Distribution + Z + Y + X Figure 3. SLX CAD outline with ray data and bounding box. The location of best focal point for the LED is at z=-0.3 mm. (Also called pseudo focal point.) a. This point is the best location for a virtual source replacing the LED. b. This point is the best focal point for secondary Fresnel lenses. c. This point is NOT the origin for the ray data sources provided. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 4
Figure 4. SLX focal point. The typical intensity distribution is shown in two cross sections: a. horizontal: through x axis b. vertical: through y-axis 2 1.8 cd/lm 1.6 1.4 Intensity (cd/lm) 1.2 1 0.8 0.6 0.4 0.2 0-100 -80-60 -40-20 0 20 40 60 80 100 Angle (deg) Figure 5. Typical intensity distribution (2 cross sections). More light is distributed toward the end of the horizontal axis. This is to enable the homogeneous appearance of the LED. Optical rayset data for SLX are available upon request and can be downloaded from the Lumileds website. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 5
2.3. Illuminance Distribution The spread of the illuminated rectangle increases with a longer distance from the LED. Figures 6-8 illustrate the typical illuminance distributions at three different distances from the LED: 53.6 mm 14.4 mm Figure 6. Typical illuminance distribution at z = 10mm from lens base. 105.6 mm 28.4 mm Figure 7. Typical illuminance distribution at z = 20mm from lens base. 157.6 mm 42.4 mm Figure 8. Typical illuminance distribution at z = 30mm from lens base. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 6
The illuminance distribution dimensions can be calculated as follows: a. x-width = 5.2mm * f + 1.6mm b. y-width = 1.4mm * f + 0.42mm Where f represents the distance between the optic and the lens base surface in mm. These values indicate also the recommended pitch (= distance between LEDS) of LEDs in x direction and y direction to generate a homogeneous illuminance. Figure 9. Calculating the illuminance distribution dimensions. Using the formulas indicated above, the following table indicates some typical dimensions of the SLX illuminance distribution as a result of the distance between the optic and the SLX lens base as well as the distance to the SLX clinch frame: Table 1. Lit Up Area as Function of Distance Between LED and Lens. DISTANCE F TO LENS BASE (IN MM) DISTANCE D TO CLINCH FRAME (IN MM) FULL WIDTH W IN X-DIRECTION (IN MM) FULL WIDTH H IN Y-DIRECTION (IN MM) 10 15.1 53.6 14.4 15 20.1 79.6 21.4 20 25.1 105.6 28.4 25 30.1 131.6 35.4 30 35.1 157.6 42.4 35 40.1 183.6 49.4 40 45.1 209.6 56.4 45 50.1 235.6 63.4 50 55.1 261.6 70.4 AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 7
2.4. Optical Application Examples SLX is an innovative new lens shape. As such the expectation is that SLX will lead to new optical applications architectures that are not designed yet on the road today. SLX can also help to create existing optical applications with less number of components and less optical complexity in the secondary optics. Here is an overview of optical application architectures for which SLX is a well suitable LED (the possibilities are not limited to this list): a. Direct lit, single diffuser. b. Direct lit, double diffuser c. Indirect lit, white box d. Direct lit, Fresnel lens with spreading optics e. Indirect lit, pillow mirror Please find a summary of each optical architecture explained in below table. In the remainder of this chapter, the specifics of each optical architecture will be explained in more detail. Table 2. Example of Optical Reference Designs for SnapLED Xtreme. ARCHITECTURE ELEMENTS APPLICATION REMARK a. Direct Lit, Single Diffuser LED, Diffuser Tail Difficult to maintain uniformity in overlap regions due to extreme incidence angles. b. Direct Lit, Double Diffuser LED, First Diffuser, Second Diffuser Tail Good to form lit 3D sculptures with glowing lit appearance works well with 3D-arrangements, orient LED axis perpendicular to target surface. c. Indirect lit, white box LED, Diffuse Reflector, Diffuser Tail Avoid direct view on LED, arrange primary lit surface perpendicular to LED-axis works well with 3D-arrangements. d. Direct Lit, Fresnel lens with spreading optics LED, Fresnel lens, spreading element Stop, Turn, Rear Fog, Tail Set focal point of Fresnel lens to best focal point of LED, spreading optics can be cushion lenses, diffuser or cushion mirror. In 3D arrangement, orient LED-axis and Fresnel-Lens axis at HV. Use stepped arrangement to follow 3D contour with spreading optics on cover. e. Indirect lit, pillow mirror LED-cushion mirror Stop, Turn, Rear Fog, Tail Choose plane base surface perpendicular to LED axis. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 8
2.4.1. Optical Reference Design 1: Direct Lit Diffuser The first optical reference solution for SnapLED Xtreme is the direct lit diffuser. Although it is a very cheap and easy solution, it does not produce highly uniform lit appearance. Figure 10. Example of direct lit diffuser. Elements that are used in this solution: 1. SnapLED Xtreme LEDs 2. Diffuse Screen. Can be either from surface structure or volume scattering material. 3. Diffuse side walls for further uniformity Characteristics of this solution are: simple architecture (Just LED and diffuser) cheap system (least number of components) difficult for uniform luminance strong effects in overlapping regions high risk for directional effects suitable for tail function If this solution is chosen, please take care to: have double scattering layer or volume diffuser for screen to reduce effects of overlapping and directional effects provide side walls with diffuse reflection provide alignment of LEDs parallel to target surface Figure 11. Example direct lit diffuser lit up appearance. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 9
2.4.2. Optical Reference Design 2: Direct Lit Double Diffuser The second optical reference solution overcomes the disadvantages of the first solution by adding a diffuser in between the LED and the visible optic. Figure 12. Example setup of direct lit double diffuser demonstrator. Elements that are used in this solution: 1. SnapLED Xtreme LEDs 2. Double layer of diffuse screen. Can be either from surface structure or volume scattering material. 3. Diffuse side walls Characteristics of this solution are: simple to design architecture can build glowing sculptures simple uniform luminance for tail function If this solution is chosen, please take care to: avoid leakage from first chamber have strong scattering to reduce directional effects have first diffuser lit uniformly by LEDs have second diffuser following contour of first diffuser provide side walls with diffuse reflection up to first diffuser provide alignment of LEDs parallel to first surface Figure 13. Lit up appearance direct lit double diffuser demonstrator. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 10
2.4.3. Optical Reference Design 3: White Box In contrast to the first two reference designs which are more directly illuminated diffuse optics, the third reference design is using the SnapLED Xtreme light in an indirect way via lighting up a diffuse material. Figure 14. Example of white box demonstrator. Elements that are used in this solution: 1. SnapLED Xtreme LEDs 2. Diffuse white box reflector 3. Diffuse or transparent cover Characteristics of this solution are: simple to design architecture can provide uniform appearance for 3D objects requires certain minimal volume tail function If this solution is chosen, please take care to: provide bezel to block direct sight to the LEDs align the reflector surface parallel to the clinch frame surface have first diffuser lit uniformly by LEDs provide diffuse cover for optimal uniformity Figure 15. Lit up appearance white box demonstrator. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 11
2.4.4. Optical Reference Design 4: Fresnel Lens with Spreading Optic While the previous reference designs are most suitable for tail function designs, the fourth reference designs is best suitable for Stop function of RCL or CHMSL. It is much more efficient than previous designs and depending upon the chosen optic, does not compromise much from the homogenous lit appearance. Figure 16. Example of setup fresnel lens with spreading optic demonstrator. Elements that are used in this solution: 1. SnapLED Xtreme LEDs 2. Fresnel lens for collimation 3. Spreading optics, can be diffusion layer or cushion lenses In many cases 2 and 3 can be achieved in one lens, using inner side of lens for fresnel collimation and outer side of lens for spreading optics. Characteristics of this solution are: straight forward to design architecture provides high intensity bundles good uniformity with moderate stitching effects good for retrofitting existing CHMSL for stop and turn function, CHMSL, (tail) If this solution is chosen, please take care to: provide parallel alignment between Fresnel lens and LED align lenses and LED along optical axis use controlled spreading use stepped alignment for slanted arrangement block stray light in stepped arrangement Figure 17. Lit up appearance of fresnel lens with spreading optic demonstrator. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 12
2.4.5. Optical Reference Design 5: Pillow Mirror This design is most similar to design 3, the wide box with the exception that it uses a reflector instead of a diffuse material. pillow Figure 18. Example of pillow mirror demonstrator. Elements that are used in this solution: 1. SnapLED Xtreme LEDs 2. Pillow mirror for redirection and spread 3. Optional a diffuse lens can be used Characteristics of this solution are: straight forward to design architecture provides high intensity bundles moderate uniformity with dotted design offering pillow mirror appearance with fewer LEDs for stop and turn function, CHMSL, (tail) If this solution is chosen, please take care to: provide parallel alignment between LED and pillow mirror base plane avoid blocking of reflected light by LED or clinch frame avoid direct sight of LED pillow Figure 19. Lit up appearance of pillow mirror demonstrator. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 13
3. Thermal Management 3.1. Thermal Management and Clinch Frame Area Since SnapLED Xtreme is N-up chip and P side is mounted on the lead frame, most of the heat of the LED is conducted to the Anode side of the LED. To estimate the case-to-ambient thermal resistance for the SnapLED Xtreme, the following formula can be used: R qca (K/W) = 56.911e -0.0009A where K/W is the surface area of the clinch frame (anode side) oriented vertically. This formula was derived from the graph in Figure 20 which is based on benchtesting of actual devices measuring case to ambient thermal resistance at different anode clinch frame area sizes: Figure 20. Rth clinchframe to ambient as function of clinchframe area. To estimate the thermal resistance for a clinchframe system oriented horizontally, add 2.9K/W. For replication of the thermal benchtest Table 3 shows the dimensions used for measuring the thermal resistance with different anode clinch frame area s. Figure 21. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 14
Table 3. Dimensions Used for Measuring Thermal Resistance. R Width Length Area qca @ 300 Sample ma (mm 2 ) (mm 2 ) (mm 2 ) ( C * W -1 ) E1a 36.09 36.09 1302.49 19.8 E2a 31.11 31.11 967.83 17.7 E3a 25.40 25.40 645.16 31.7 E4a 21.90 21.90 479.61 32.7 E5a 17.97 17.97 322.92 27.5 E6a 10.04 64.60 648.58 37.0 E7a 10.04 32.44 325.70 49.9 4. Assembly Process Recommendations and Parameters 4.1. Mechanical Files Mechanical drawings for SLX (3D CAD) are available from the Lumileds website or upon request. For details please contact your sales representative. 4.2. Pick and Place Nozzle Figure 22 and 23 show the recommended Pick and Place nozzle dimensions. Figure 22. Top view of recommended pick and place nozzle. AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 15
Figure 23. Side view of recommended pick and place nozzle dimensions. 4.3. Handling Precautions Like all electrical components, there are handling precautions that need to be accounted for when setting up assembly procedures. The following cautions are noted for SLX: Electrostatic Discharge (ESD) protection Electrostatic Discharges, rapid transfers of charges between two bodies due to an electrical potential difference between those bodies, can cause unseen damage to electronic components. In LED devices, ESD events can result in a slow degradation of light output and/or early catastrophic failures. Common causes of ESD include the direct transfer of charges from the human body or from a charged conductive object to the LED component. In order to test the susceptibility of LEDs to these common causes of ESDs, three different models are typically used: Human Body Model (HBM) Machine Model (MM) Charged Device Model (CDM) Lumileds LEDs have been independently verified to successfully pass ESD tests for both HBM, MM and CDM at the highest AEC recommended test voltages of +/- 8000V, +/- 400V and +/-1000V, respectively. Nevertheless, Lumileds strongly recommends that customers adopt handling precautions for LEDs similar to those that are commonly used for other electronic surface mount components which are susceptible to ESD event. Additional external ESD protection for the LED is needed, if the LED is assembled or handled in environments which are not ESD protected, or if exposed to higher ESD voltages and discharge energy, e.g. as described in ISO 10605 or IEC 61000-4-2 (severity level IV). For details please contact your sales representative. 5. JEDEC Moisture Sensitivity Level Since SnapLED Xtreme is assembled via cold mechanical clinching and the LEDs are not exposed to thermal shocks, as from solder processes moisture levels are not of concern for the SLX LEDs. RoHS COMPLIANT AB125 SnapLED Xtreme Application Brief 20150330 2015 Lumileds Holding B.V. All rights reserved. 16
About Lumileds Lumileds is the light engine leader, delivering innovation, quality and reliability. For 100 years, Lumileds commitment to innovation has helped customers pioneer breakthrough products in the automotive, consumer and illumination markets. Lumileds is shaping the future of light with our LEDs and automotive lamps, and helping our customers illuminate how people see the world around them. To learn more about our portfolio of light engines visit lumileds.com. 2015 Lumileds Holding B.V. All rights reserved. LUXEON is a registered trademark of the Lumileds Holding B.V. in the United States and other countries. lumileds.com AB125 SnapLED Xtreme Application Brief 20150330 Neither Lumileds Holding B.V. nor its affiliates shall be liable for any kind of loss of data or any other damages, direct, indirect or consequential, resulting from the use of the provided information and data. Although Lumileds Holding B.V. and/or its affiliates have attempted to provide the most accurate information and data, the materials and services information and data are provided as is, and neither Lumileds Holding B.V. nor its affiliates warrants or guarantees the contents and correctness of the provided information and data. Lumileds Holding B.V. and its affiliates reserve the right to make changes without notice. You as user agree to this disclaimer and user agreement with the download or use of the provided materials, information and data.