ILLUMINATION LUXEON SunPlus 35 Line for Horticulture Assembly and Handling Information Introduction The LUXEON SunPlus Series for Horticulture is purpose-built to enable ease of system design for Horticulture applications. The LUXEON SunPlus Series offers the only LEDs available today that are binned and tested based on Photosynthetic Photon Flux (PPF). This application brief addresses the recommended assembly and handling guidelines for LUXEON SunPlus 35 Line for Horticulture. Proper assembly and handling, as outlined in this application brief, ensures high optical output and the long-term performance of LUXEON emitters. Scope The assembly and handling guidelines in this application brief apply to the all following LUXEON products: PRODUCT NAME PART NUMBER LUXEON SunPlus 35 Purple (2.5% Blue) L1SP-PRP0003500000 LUXEON SunPlus 35 Purple (12.5% Blue) L1SP-PRP1003500000 LUXEON SunPlus 35 Purple (25% Blue) L1SP-PRP2003500000 LUXEON SunPlus 35 Royal Blue L1SP-RYL0003500000 LUXEON SunPlus 35 Lime L1SP-LME0003500000 In the remainder of this document the term LUXEON emitter refers to any product in the LUXEON SunPlus 35 Line listed above. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief ©2016 Lumileds Holding B.V. All rights reserved. Table of Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Optical Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 Handling Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.4 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.5 Electrical Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.6 Mechanical Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Optical Design Consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. PCB Design Guidelines for the LUXEON Emitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1 PCB Footprint and Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.2 Surface Finishing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.3 Minimum Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Thermal Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Thermal Measurement Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6. Assembly Process Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.1 Stencil Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.2 Solder Paste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.3 Solder Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.4 Pick and Place . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.5 Electrostatic Discharge Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. LUXEON Emitter Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7.2 Active Control LED Current Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8. Packaging Considerations—Chemical Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 About Lumileds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 2 1. Component 1.1 Description LUXEON SunPlus 35 emitters (Figure 1) consist of a 3535 lead-frame package with an anode and a cathode. A small notch on the corner of the package marks the cathode side of the emitter package. The anode and cathode both serve as thermal pads for the emitter, with the majority of the heat being dissipated through the larger pad, corresponding to the cathode. The LUXEON emitter does not include any transient voltage suppressor (TVS) chip to protect the emitter against electrostatic discharges (ESD). Appropriate precautions should therefore be taken when handling this device (see Section 5.5). 1.2 Optical Center The optical center coincides with the mechanical center of the LUXEON emitter. Optical rayset data for the LUXEON emitter are available on the Lumileds website at lumileds.com. 1.3 Handling Precautions The LUXEON emitter is designed to maximize light output and reliability. However, improper handling of the device may damage the silicone coating and affect the overall performance and reliability. In order to minimize the risk of damage to the silicone coating during handling, the LUXEON emitter should only be picked up from the side of the package. 1.4 Cleaning The LUXEON emitter should not be exposed to dust and debris. Excessive dust and debris may cause a drastic decrease in optical output. In the event that a LUXEON emitter requires cleaning, first try a gentle swabbing using a lint-free swab. If needed, a lint-free swab and isopropyl alcohol (IPA) can be used to gently remove dirt from the silicone coating. Do not use other solvents as they may adversely react with the package of the LUXEON emitter. For more information regarding chemical compatibility, see Section 6. 1.5 Electrical Isolation The LUXEON emitter has two electrodes, with a nominal spacing of 0.65mm, at the bottom of the package. In addition, the LUXEON emitter contains two tabs on the side of the package. These tabs are cut-off remnants of the lead-frame and are electrically connected to the anode and cathode, respectively. So it is important to keep sufficient distance between the LUXEON emitter package and any other objects or neighboring LUXEON emitters to prevent any accidental shorts. In order to avoid any electrical shocks and/or damage to the LUXEON emitter, each design needs to comply with the appropriate standards of safety and isolation distances, known as clearance and creepage distances, respectively (e.g. IEC60950, clause 2.10.4). Figure 1. Package rendering of a representative LUXEON emitter. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 3 2.60 2.40 0.82 1.02 Solder mask 0.25 0.65 0.30 Stencil Top copper Package geometric center 1.93 1.80 2.13 Package and pad outlines 0.50 0.50 Figure 2. Recommended PCB footprint design for the LUXEON emitter. In order to ensure proper heat dissipation from the package electrodes to the PCB, it is best to extend the top copper layer at least 3 mm beyond the package of the LUXEON emitter. All dimensions are in mm. 1.6 Mechanical Files Mechanical drawings for the LUXEON emitter are available on the Lumileds website at lumileds.com. 2. Optical Design Consideration To ensure optimum plant growth and power efficiency with artificial lights, there are two important optical design considerations: a. Uniform light and color (spectral) distribution. To avoid negative effects from phototropism, a high level of light uniformity is required. The main plant stem will grow towards the light source (minimize “hot spots”). The lower section of the plant leaves may be shadowed by the upper section thus reducing photosynthesis. Choosing the right LEDs, light source placement and/or using secondary optics (e.g. reflectors or lenses) can help to achieve the desired objective. While not yet proven, some studies have shown that the blue light promotes vegetative growth while the red light aids in fruiting and flowering, so a good mixing of such colors is sometimes essential. b. Maintain optimum PPFD (photosynthetic photon flux density in µmol/s/m2) level. PPFD follows inverse square law, i.e. it will change to the square distance from the plant. For area being illuminated, it follows the square law. Note that beyond certain optimum PPFD level, the rate of photosynthesis tapers off with increasing PPFD, thus reducing the rate of return on power consumption versus plant growth rate. The optimum PPFD level varies with each plant type. Please visit the Lumileds website for downloading optical rayset files, IES file format (per LM-63-02) and using Lumileds Design Tools for optical design and simulations. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 4 3. PCB Design Guidelines for the LUXEON Emitter The LUXEON emitter is designed to be soldered onto a Printed Circuit Board (PCB). To ensure optimal operation, the PCB should be designed to minimize the overall thermal resistance between the LED package and the heat sink. 3.1 PCB Footprint and Land Pattern The recommended PCB footprint design for the LUXEON emitter is shown in Figure 2. In order to ensure proper heat dissipation from the emitter electrodes to the PCB, it is best to extend the top copper layer of the PCB beyond the perimeter of the LUXEON emitter by at least 3mm (see Section 4). 3.2 Surface Finishing Lumileds recommends using a high temperature organic solderability preservative (OSP) or electroless nickel immersion gold (ENIG) plating on the exposed copper pads. 3.3 Minimum Spacing Lumileds recommends a minimum edge to edge spacing between LUXEON emitters of 0.5mm. Placing multiple LUXEON emitters too close to each other may adversely impact the ability of the PCB to dissipate the heat from the emitters and may cause accidental shorts between the metal stubs on the side of neighboring LUXEON emitters. Figure 3. Top copper trace patterns showing the maximum (optimized and standard) and minimum top side metallization. For the maximum copper design, one can optimize the copper trace pattern to take into account that the heat is mainly dissipated from the cathode pad. There is no need to have large copper area around the anode. 4. Thermal Management The overall thermal resistance between a LUXEON emitter and the heat sink is strongly affected by the design and material of the PCB on which the emitter is soldered. On FR4 based PCB, the following general guidelines will yield optimum thermal performance: –– thicker top copper layer, for e.g. 2 oz versus 1 oz copper –– at least 3mm of top copper layer extending outside the LED package. Table 1 shows the result of the thermal resistance from junction to heat sink using two boards with different copper areas surrounding the LED package (Figure 3) –– top copper trace pattern layout. Figure 3 shows the optimized max copper (optimized) layout versus standard max copper (standard) layout. The former will yield lower board thermal resistance Note that using double sided FR4 board will not yield noticeable improvement in the board thermal resistance. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 5 On Al-MCPCB, the following additional guidelines on top of the FR4 guidelines can improve the thermal performance: –– thinner dielectric layer. Trade-off between thinner dielectric and PCB electrical insulation barrier must be considered –– dielectric with high thermal conductivity property. On a system level, high density LED packing (small LED to LED spacing) will increase the overall LED thermal resistance when compare to low density LED packing. Table 1. Typical junction-to-heat sink thermal resistance values for FR4 board with minimum and maximum copper (standard) top side metallization. Top Side Metallization Pattern (Figure 3) Rθj-HEAT sink [K/W] Minimum copper 100 Maximum copper (standard) 58 Figure 4. The recommended temperature measurement point Ts is located right next to the cathode of the LUXEON emitter on the PCB. 5. Thermal Measurement Guidelines The typical thermal resistance Rθj-case between the junction and the solder pads of the LUXEON emitter is provided in the datasheet. With this information, the junction temperature Tj can be determined according to the following equation: Tj = Tcase + Rθj-case• Pelectrical In this equation Tcase is the temperature at the bottom of the solder pads of the LUXEON emitter and Pelectrical is the electrical power going into the emitter. In typical applications it may be difficult, though, to measure the temperature Tcase directly. Therefore, a practical way to determine the junction temperature of the LUXEON emitter is by measuring the temperature Ts of a predetermined sensor pad on the PCB with a thermocouple. The recommended location of the sensor pad is right next to the cathode of the LUXEON emitter on the PCB, as shown in Figure 4. To ensure accurate readings, the thermocouple must make direct contact with the copper of the PCB onto which the LUXEON emitter pads are soldered, i.e. any solder mask or other masking layer must be first removed before mounting the thermocouple onto the PCB. The thermal resistance Rθj-s between the sensor pad and the LUXEON emitter junction was experimentally determined on various PCBs as shown in Table 2. The junction temperature can then be calculated as follows: Tj = Ts + Rθj-s• Pelectrical AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 6 Table 2. Typical junction-to-Ts thermal resistance values for various devices with different PCB constructions. Device Top side metallization pattern (Figure 3) PCB specification Typical Rθj-s (K/W) LUXEON SunPlus 35 L1SP-PRPxx03500000 Maximum copper (optimized) 1oz copper, 1mm thick Al-MCPCB with 2W/(mK), 100μm dielectric 32 LUXEON SunPlus 35 L1SP-RYLxx03500000 Maximum copper (optimized) 1oz copper, 1mm thick Al-MCPCB with 2W/(mK), 100μm dielectric 37 LUXEON SunPlus 35 L1SP-LMExx03500000 Maximum copper (optimized) 1oz copper, 1mm thick Al-MCPCB with 2W/(mK), 100μm dielectric 27 6. Assembly Process Guidelines 6.1 Stencil Design The recommended solder stencil thickness is 125μm. 6.2 Solder Paste Lumileds recommends lead-free solder for the LUXEON emitter. Lumileds tested SAC 305 solder paste from Alpha Metals (OM338 grade 3 and OM 325 grade 4) with satisfactory results. However, since application environments vary widely, Lumileds recommends that customers perform their own solder paste evaluation in order to ensure it is suitable for the targeted application. 6.3 Solder Reflow Profile The LUXEON emitter is compatible with standard surface-mount and lead-free reflow technologies. This greatly simplifies the manufacturing process by eliminating the need for adhesives and epoxies. The reflow step itself is the most critical step in the reflow soldering process and occurs when the boards move through the oven and the solder paste melts, forming the solder joints. To form good solder joints, the time and temperature profile throughout the reflow process must be well maintained. A temperature profile consists of three primary phases: 1. Preheat: the board enters the reflow oven and is warmed up to a temperature lower than the melting point of the solder alloy. 2. Reflow: the board is heated to a peak temperature above the melting point of the solder, but below the temperature that would damage the components or the board. 3. Cool down: the board is cooled down rapidly, allowing the solder to freeze, before the board exits the oven. As a point of reference, the melting temperature for SAC 305 is 217°C and the minimum peak reflow temperature is 235°C. 6.4 Pick and Place The LUXEON emitter is packaged and shipped in tape-and-reel which is compatible with standard automated pick-andplace equipment to ensure the best placement accuracy. Note that pick and place nozzles are customer specific and are typically machined to fit specific pick and place tools. In selecting a suitable nozzle size for picking up these LUXEON emitters, there are two important factors to consider: 1. The nozzle outer diameter should not be larger than the opening of the reel pocket tape otherwise it may interfere with the pocket tape cavity during the pick-up process. See respective datasheets for tape and reel dimensions. 2. The nozzle outer diameter should also not be smaller than the Light Emitting Surface (LES) diameter (Figure 1) otherwise this may allow the nozzle tip to be in full contact with the silicone-filled LES area and may cause damage to the surface or cause pick-up/release issues. Recommended outer diameter is 3.5mm. There are two LES diameters for LUXEON emitters; 2.6mm and 3.0mm. See respective datasheets for mechanical package dimensions. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 7 One nozzle that meets the above criteria and suitable for picking up the LUXEON emitters is shown in Figure 5. Figure 5. An example of nozzle “505” for Juki KE2080L pick and place machine suitable for picking up LUXEON emitters. It has an outer diameter of 3.5mm and inner diameter of 1.7mm. 6.5 Electrostatic Discharge Protection The LUXEON emitter does not include any transient voltage suppressor (TVS) chip to protect against electrostatic discharges (ESD). Therefore, Lumileds recommends observing the following precautions when handling the LUXEON emitter: • During manual handling always use a conductive wrist band or ankle straps when positioned on a grounded conductive mat. • All equipment, machinery, work tables and storage racks that may get in contact with the LUXEON emitter should be properly grounded. • Use an ion blower to neutralize the static discharge that may build up on the surface and lens of the plastic housing of the LUXEON emitter during storage and handling. LUXEON emitters which are damaged by ESD may not light up at low currents and/or may exhibit abnormal performance characteristics such as a high reverse leakage current and a low forward voltage. To determine whether any device is damage by ESD, measure the light output and forward voltage of the emitter which is suspect. A forward voltage above 2.0V for a drive current of 0.1mA typically indicates that the LED is not damaged. 7. LUXEON Emitter Drivers 7.1 Introduction LED is best driven with current source. This mode of operation provides the best control of the amount of current flowing through the LEDs at any operating temperature. A voltage source does not provide a predetermined current, may vary significantly and depends on the forward voltage and the operating temperature of the LEDs. However a voltage source can be assembled with few passive components such resistor, capacitor and bridge rectifier, assuming incoming AC power supply. Such configuration is cheap and compact but has poor power efficiency and poor current control. This section discusses LED current drivers via active controls (more common) incorporating transistors and linear ICs such as constant current regulators (CCRs). AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 8 7.2 Active Control LED Current Driver There are two types of active control LED current drivers: –– Linear regulated power supply –– Switch mode power supply The main difference is how the power supply is being regulated. In linear regulated power supply, the transistor connected to a load is used to control the output voltage or current. In order to do this, the transistor must operate in the ohmic or linear region as shown in Figure 6. Since there is current flowing through the transistor (operating in ohmic region), the transistor behaves like a variable resistor and generates heat. In a switched mode power supply, as the name implies, the transistor is used as a switch to either switch in or out electrical storage elements such as inductor (current source) or capacitor (voltage source) to a load. In order to achieve this, the transistor must be operating in the saturation region as shown in Figure 6. In the “ON” or close switch, there is hardly any resistance through the transistor and hence does not generate any heat when a current flows through it. In “OFF” or open switch, no current is flowing through the transistor. This type of power supply has high power efficiency than the linear regulated power supply. However due to the switching of the circuit, it generates electromagnetic interference (EMI) which must be taken into account and minimized during the design stage. There are several switch mode power supply configurations such as buck, boost and buck-boost convertor. Figure 6. Typical transistor operation regions. Ohmic or linear region is shaded in yellow while the saturation or switching region is shaded green. A summary of the major differences between these two active control LED current drivers is given in Table 3 below. Table 3. Comparison of a typical linear regulated versus switch mode power supply. Linear Switch Mode Cost Cheap Expensive EMC None Potential Circuitry Simple Complicated Power Efficiency Low (~50...~70%) High (~75%...~95%) Size and Weight Big and heavy 1 Small and light Notes for Table 3: 1. If magnetics are used to step down the voltage before the regulator. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 9 A typical example of an AC-DC LED system block circuit may consist of a bridge rectifier, transient circuit protection (e.g. varistor), dimming circuit (triac) and a control circuit (either passive or active control) with flicker-free, over-voltage protection, filters and/or feedback loop circuits. Figure 7 shows an example of a system block diagram of a typical LED driver circuit. Lumileds maintain a list of various linear IC driver manufacturers. Examples of various driver circuit designs are provided by each manufacturer. To access this information, go to Lumileds website at lumileds.com. Navigate to the “Design Tools” section and click on “LOGIN” (Figure 8). Follow the login process or the instructions to “Create an account.” Within the “Lumileds Design Tools,” click on “Eco-System” to access the “Drivers” tab. Figure 7. A typical system block diagram of one example of a LED driver circuit. Figure 8. Screenshots on how to navigate to the LED drivers eco-system. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 10 8. Packaging Considerations—Chemical Compatibility The LUXEON emitter package contains a silicone overcoat to protect the LED chip and extract the maximum amount of light. As with most silicones used in LED optics, care must be taken to prevent any incompatible chemicals from directly or indirectly reacting with the silicone. The silicone overcoat used in the LUXEON emitter is gas permeable. Consequently, oxygen and volatile organic compound (VOC) gas molecules can diffuse into the silicone overcoat. VOCs may originate from adhesives, solder fluxes, conformal coating materials, potting materials and even some of the inks that are used to print the PCBs. Some VOCs and chemicals react with silicone and produce discoloration and surface damage. Other VOCs do not chemically react with the silicone material directly but diffuse into the silicone and oxidize during the presence of heat or light. Regardless of the physical mechanism, both cases may affect the total LED light output. Since silicone permeability increases with temperature, more VOCs may diffuse into and/or evaporate out from the silicone. Careful consideration must be given to whether LUXEON emitters are enclosed in an “air tight” environment or not. In an “air tight” environment, some VOCs that were introduced during assembly may permeate and remain in the silicone. Under heat and “blue” light, VOCs captured inside the silicone may partially oxidize and create a silicone discoloration, particularly on the surface of the LED where the flux energy is the highest. In an air rich or “open” air environment, VOCs have a chance to leave the area (driven by the normal air flow). Transferring the devices which were discolored in the enclosed environment back to “open” air may allow the oxidized VOCs to diffuse out of the silicone and may restore the original optical properties of the LED. Determining suitable threshold limits for the presence of VOCs is very difficult since these limits depend on the type of enclosure used to house the LEDs and the operating temperatures. Also, some VOCs can photo-degrade over time. Table 4 provides a list of commonly used chemicals that should be avoided as they may react with the silicone material. Note that Lumileds does not warrant that this list is exhaustive since it is impossible to determine all chemicals that may affect LED performance. The chemicals in Table 4 are typically not directly used in the final products that are built around LUXEON emitters. However, some of these chemicals may be used in intermediate manufacturing steps (e.g. cleaning agents). Consequently, trace amounts of these chemicals may remain on (sub)components, such heat sinks. Lumileds, therefore, recommends the following precautions when designing your application: –– When designing secondary lenses to be used over an LED, provide a sufficiently large air-pocket and allow for “ventilation” of this air away from the immediate vicinity of the LED. –– Use mechanical means of attaching lenses and circuit boards as much as possible. When using adhesives, potting compounds and coatings, carefully analyze its material composition and do thorough testing of the entire fixture under High Temperature over Life (HTOL) conditions. AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 11 Table 4. List of commonly used chemicals that will damage the silicone of the LUXEON emitter. Avoid using any of these chemicals in the housing that contains the LED package. Chemical Name Normally used as Hydrochloric acid acid Sulfuric acid acid Nitric acid acid Acetic acid acid Sodium hydroxide alkali Potassium hydroxide alkali Ammonia alkali MEK (Methyl Ethyl Ketone) solvent MIBK (Methyl Isobutyl Ketone) solvent Toluene solvent Xylene solvent Benzene solvent Gasoline solvent Mineral spirits solvent Dichloromethane solvent Tetracholorometane solvent Castor oil oil Lard oil Linseed oil oil Petroleum oil Silicone oil oil Halogenated hydrocarbons (containing F, Cl, Br elements) misc Rosin flux solder flux Acrylic tape adhesive RoHS COMPLIANT AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 ©2016 Lumileds Holding B.V. All rights reserved. 12 About Lumileds Lumileds is the global leader in light engine technology. The company develops, manufactures and distributes groundbreaking LEDs and automotive lighting products that shatter the status quo and help customers gain and maintain a competitive edge. With a rich history of industry “firsts,” Lumileds is uniquely positioned to deliver lighting advancements well into the future by maintaining an unwavering focus on quality, innovation and reliability. To learn more about our portfolio of light engines, visit lumileds.com. ©2016 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 AB171 LUXEON SunPlus 35 Line for Horticulture Application Brief 20161110 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.