Application Brief AB29 LUXEON® K2 Power LEDs Assembly and Handling Information Table of Contents ue d Introduction This application brief covers the recommended handling procedures ® Pick and Place . . . . . . . . . . . . . . . .2 for LUXEON K2 Power Light Emitting Diodes (LEDs). Specifications Lens Handling . . . . . . . . . . . . . . . .2 and procedures are also included for the proper surface mounting of Lens Cleaning . . . . . . . . . . . . . . . . .3 nt in these emitters on printed circuit boards (PCBs). The LUXEON K2 emitters have a silicone lens, which offers enhanced optical properties and improved reliability. However, silicone is a softer Pad Layout . . . . . . . . . . . . . . . . . . .3 Stencil Thickness and Coverage . . .4 Reflow Profile . . . . . . . . . . . . . . . . .5 Electrical Slug Isolation . . . . . . . . . .5 Board Placement Tolerance . . . . . .8 handling imperative to avoid damage to the emitters. JEDEC Moisture Sensitivity Level . .9 D is co material and prone to attracting dust. These properties make proper Pick and Place Automated pickandplace equipment provides the best placement of LUXEON K2 emitters. For LUXEON K2 pick and place, Philips Lumileds is recommending pickup from the lens but only under the guidelines below. · The collet surface is the same profile as the LUXEON K2 lens · The nozzle will suck up the LUXEON K2 unit from the tape while the tip of the collet is 0.2mm above the lens · The pressure required to lift the LUXEON K2 is between 70 to 75Kpa · The nozzle will purge the unit 0.15mm from the board surface with a pressure of 515Kpa · The 0.15mm distance corresponds to the recommended thickness of the stencil · Employ an active aligner with a camera that can adjust for any skew Figure 1 shows an example of a pickandplace nozzle suitable for use with LUXEON K2 emitters. ue d R = 2.00 2.80 3.5 nt in R = 2.85 0.40 co Figure 1. Pickandplace collet. Lens Handling D is When utilizing a pickandplace machine, the collet must not place excessive pressure on the lens of the LED. Ensure the inner surface of the collect is clean; the collet's dimensions are correct; and the correct pressure is applied. Similar restrictions exist for manual handling. The LEDs should only be picked up by making contact with the sides of the LED body; the hand tool should not put any pressure on the lens. Do not puncture or push the lens. Figures 2 and 3 illustrate correct and incorrect handling. Figure 2. Correct handling of LUXEON K2 emitters. LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) Figure 3. Incorrect handling do not grip the lens. 2 Lens Cleaning Each LUXEON K2 emitter has a silicone lens. There are many benefits to the silicone lens in terms of optical properties and improved reliability; however, silicone is a softer material and prone to attract dust. While a minimal amount of dust and debris on the LED will not cause significant reductions in illumination, steps should be taken to keep the emitter free of dust. These include keeping the LUXEON K2 Power LEDs in the manufacturer's package prior to assembly and storing assemblies in an enclosed area after installing the emitters. In the event that an emitter requires cleaning, use isopropyl alcohol to gently remove dirt from the lens. Do not use other solvents as they may adversely react with the LED assembly. Pad Layout Users may be interested in creating a layout pad suitable for LUXEON K2 and LUXEON I, III, and V LED placement. This section shows a comparison of the footprint of a LUXEON I, III or V LED on a LUXEON K2 pad layout. ue d The pad layouts for LUXEON K2 and LUXEON I, III or V LEDs are shown in Figure 4 and 5. Figure 4 is the recommended pad layout to achieve the most accurate reflow result for LUXEON K2 LEDs. Figure 5 is the recommended pad for LUXEON I, III, and V LEDs. nt in Figure 6 shows the resulting placement if a LUXEON I, III or V device is placed on the LUXEON K2 pad layout. As indicated, the LUXEON I, III or V leads will hang beyond the LUXEON K2 pads. To compensate for the overhang, users can extend the LUXEON K2 pads to match the size of the pads for the other LUXEON LEDs. Figure 7 shows the LUXEON K2 footprint on the LUXEON I, III or V pad layout. The unconnected LUXEON K2 lead pins are shown floating, with no pads. To achieve higher reflow accuracy, users can add two pads for the unconnected LUXEON K2 lead pins. D is co Philips Lumileds only recommends populating LUXEON K2 and LUXEON I, III, and V LEDs on the pads indicated in Figures 4 and 5 respectively. Figure 4. Recommended pad layout for LUXEON K2 devices. LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) Figure 5. Recommended pad layout for LUXEON I, III, and V devices. 3 Pad Layout, Continued Figure 7. LUXEON K2 footprint on a LUXEON I, III or V pad layout. ue d Figure 6. Standard LUXEON footprint on LUXEON K2 pad layout. Stencil Thickness and Coverage D is co nt in The coverage on the pad and thickness of the stencil affect reflow accuracy. A thickness of 0.15mm and 100percent stencil coverage are recommended for the LUXEON K2 emitters (see Figure 8). This configuration minimizes the voiding of the solder. Figure 8. Stencil coverage (shown in red). LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) 4 Reflow Profile nt in ue d LUXEON K2 emitters are compatible with surface mount technology and leadfree reflow. This greatly simplifies the manufac turing process by eliminating the need for adhesives and epoxies. The robustness of the emitters is evident in that LUXEON K2 LEDs can be reflowed three times without degrading performance. The reflow solder profile is compatible with JEDEC 020c (see Figure 9). The profile feature points are shown in Table 1, where all temperature points refer to the top side of the package, measured on the body surface of the package. JEDEC 020c Figure 9. JEDEC 020c reflow solder profile. co Table 1. JEDEC 020c profile feature points. Lead Free Assembly 3°C / second max Preheat Temperature Min ( Tsmin) 150°C Preheat Temperature Max ( Tsmax) 200°C Preheat Time ( tsmin to tsmax) 60 180 seconds Temperature ( TL ) 217°C Time Maintained Above Temperature ( TL ) 60 150 seconds Peak / Classification Temperature ( TP ) 260°C Time Within 5°C of Actual Peak Temperature ( TP ) 20 40 seconds RampDown Rate 6°C / second max D is Profile Feature Average RampUp Rate ( Tsmax to Tp ) Electrical Slug Isolation Similar to the LUXEON I, III, and V, the slug of the LUXEON K2 must be electrically isolated from the anode, cathode, and other slugs. This requirement stems from the basic internal construction of InGaN LUXEON K2 devices (see Figure 10). The InGaN LED is placed onto a silicon submount consisting of zener diodes. The zener diodes, which provide ESD protection to the LED, are connected to the slug and LED as shown in Figure 11. If the slug were not electrically isolated but connected to the anode, cathode, or other LED slugs, the zeners could shunt the current away from the LED. LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) 5 ue d Electrical Slug Isolation, Continued Figure 10. Basic construction of the InGaN LED. nt in Anode co Slug D is Cathode Figure 11. Zener diode connection to slug and LED. Figure 12. Basic construction of the LUXEON K2 AlInGaP LED. LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) 6 Electrical Slug Isolation, Continued Consider a situation where three InGaN LEDs are connected in series with an electrically common slug. This schematic is shown in Figure 13. Heat Sink Figure 13. Three InGaN LEDs in series with the slug on the same potential. ue d This configuration shorts the inner four zeners so that only the two outer zeners will protect the LEDs. The breakdown of one zener set can occur at levels as low as 7V. If the zeners break down, current will pass through the zeners and not the LEDs. This situation is shown in Figure 14. nt in ⊕ Bias x x x x co Heat Sink D is Figure 14. Result of electrically common heatslugs for InGaN LEDs. The same situation can be considered for an AlInGaP LED where the slug is electrically connected to the anode. The effects of connecting three AlInGaP LEDs in series with an electrically common heatslug are shown in Figure 15. This situation will render two LEDs nonactive. ⊕ Bias Heat Sink Figure 15. Result of electrically common heatslugs for LUXEON K2 AlInGaP LEDs. LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) 7 Board Placement Tolerance For many PCB designs, accurate placement of the LUXEON K2 is critical. To meet accuracy requirements, the center of the LUXEON K2 emitter must be correctly determined in respect to the center of the hexagonal pad. This can be accomplished using the following procedure (see Figure 16): 1. Locate the two "bite" marks on the LUXEON K2 emitter package. 2. Find the center of the circle formed from the "bite" marks. 3. Draw a line connecting the centers of the two circles. 4. The midpoint of the line is the center of the LED. 5. Record the coordinates of this point (x1, y1). The 1. 2. 3. center of the LUXEON K2 hexagonal pad is found as follows (see Figure 17): Draw a circle that touches the six hexagonal points of the pad. The center point of this circle is the center of the hexagonal pad Record this point (x2, y2). co nt in ue d The offset between the LED center and the center of the hexagonal pad is (x1x2) and (y1y2). Philips Lumileds utilized the OGP Smart Scope for this exercise. Any scope or shadowgraph that is capable of finding and storing the centers of circles may be used for this measurement. D is Figure 16. Finding the center of the LED. Figure 17. Finding the center of the pad. LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) 8 JEDEC Moisture Sensitivity Level LUXEON K2 Power LEDs are shipped in vacuumpacked airtight containers. Breaking this vacuum allows the introduction of moisture into the LED, and can potentially result in damage to the package during assembly. During soldering or reflow, the moisture will expand as the temperature rises, causing the package to crack. JEDEC has defined eight levels for moisture sensitivity, as shown in Table 2. The LUXEON K2 emitter offers superior performance with a Moisture Sensitivity Level of 2a and a floor life of four weeks before any bake out is required. For emitters that exceed the shelf life, the bake out condition is 67 days at 40°C, as shown in Table 3. Table 2. JEDEC Moisture Sensitivity Levels. Soak Requirements Floor Life Standard Time Conditions (hours) Time Conditions 1 Unlimited ≤ 30°C / 85% RH 168 + 5/0 2 1 year ≤ 30°C / 60% RH 168 + 5/0 2a 4 weeks ≤ 30°C / 60% RH 6962 + 5/0 3 168 hours ≤ 30°C / 60% RH 1922 + 5/0 4 72 hours ≤ 30°C / 60% RH 5 48 hours ≤ 30°C / 60% RH 5a 24 hours ≤ 30°C / 60% RH 6 Time on Label (TOL) 85°C / 85% RH 85°C / 60% RH 120 +1/0 60°C / 60% RH 30°C / 60% RH 40 +1/0 60°C / 60% RH 962 + 2/0 30°C / 60% RH 20 +0.5/0 60°C / 60% RH 722 + 2/0 30°C / 60% RH 15 +0.5/0 60°C / 60% RH 482 + 2/0 30°C / 60% RH 10 +0.5/0 60°C / 60% RH TOL 30°C / 60% RH co nt in 30°C / 60% RH D is ≤ 30°C / 60% RH Accelerated Environment Time Conditions (hours) ue d Level LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) 9 JEDEC Moisture Sensitivity Level, Continued Table 3. JEDEC Bake Out Specifications. Bake at 125°C Bake at 90°C ≤ 5% RH Saturated @ 30°C 85% RH At Limit of Floor Life +72 hr @ 30°C 60% RH Saturated @] 30°C 85% RH At Limit of Floor Life +72 hr @ 30°C 60% RH ≤ 1.4 mm 2a 3 4 5 5a 5 hours 9 hours 11 hours 12 hours 16 hours 3 hours 7 hours 7 hours 7 hours 10 hours 17 33 37 41 54 hours hours hours hours hours 11 23 23 24 24 ≤ 2.0 mm 2a 3 4 5 5a 21 27 34 40 48 hours hours hours hours hours 16 17 20 25 40 hours hours hours hours hours 3 4 5 6 8 days days days days days 2 2 3 4 6 ≤ 4.5 mm 2a 3 4 5 5a 48 48 48 48 48 hours hours hours hours hours 48 48 48 48 48 hours hours hours hours hours 10 10 10 10 10 days days days days days nt in co D is LUXEON K2 Assembly & Handling Information Application Brief AB29 (3/07) Saturated @ 30°C 85% RH At Limit of Floor Life +72 hr @] 30°C 60% RH hours hours hours hours hours 8 days 13 days 15 days 17 days 22 days 5 days 9 days 9 days 10 days 10 days days days days days days 29 37 47 57 79 days days days days days 22 23 28 35 56 days days days days days 7 days 8 days 10 days 10 days 10 days 79 79 79 79 79 days days days days days 67 67 67 67 67 days days days days days ue d Level Package Body Thickness Bake at 40°C ≤ 5% RH 10 Company Information ue d LUXEON® is developed, manufactured and marketed by Philips Lumileds Lighting Company. Philips Lumileds is a worldclass supplier of Light Emitting Diodes (LEDs) producing billions of LEDs annually. Philips Lumileds is a fully integrated supplier, producing core nt in LED material in all three base colors (Red, Green, Blue) and White. Philips Lumileds has R&D centers in San Jose, California and in Philips Lumileds may make process or materials changes affecting the perform ance or other characteristics of our products. These products supplied after such changes will continue to meet published specifications, but may not be identical to products supplied as samples or under prior orders. The Netherlands and production capabilities in San Jose and Penang, Malaysia. Founded in 1999, Philips Lumileds is the highflux LED co technology leader and is dedicated to bridging the gap between solidstate LED technology and the lighting world. Philips Lumileds technology, LEDs and systems are enabling new applications and D is markets in the lighting world. www.luxeon.com www.lumiledsfuture.com For technical assistance or the location of your nearest sales office contact any of the following: North America: +1 888 589 3662 or [email protected] Europe: 00 800 443 88 873 or [email protected] ©2007 Philips Lumileds Lighting Company. All rights reserved. Product specifications are subject to change without notice. Luxeon is a registered trademark of the Philips Lumileds Lighting Company in the United States and other countries. Asia: 800 5864 5337 or [email protected]