Lumileds Luxeon multicolor module 2.5w User manual

ILLUMINATION

LUXEON MultiColor

Module 2.5W

Assembly and Handling Information

Introduction

This application brief addresses the recommended assembly and handling

guidelines for LUXEON MultiColor Module 2.5W emitters. This compact 4-in-

1 package makes color tuning easier. Each channel is individually addressable,

enabling a large color gamut while simplifying the ability of getting just the right

color point. Proper assembly, handling, and thermal management, as outlined in this

application brief, ensures high optical output and reliability of these emitters.

Scope

The assembly and handling guidelines in this application brief apply to LUXEON

MultiColor Module 2.5W with the following part number designation:

L 1 M C – A A A B B C C D D E M P 0

Where:

A A A – designates color (R=Red, G=Green, B=Blue)

B B – designates CCT (30=3000K)

C C – designates CRI (80=80CRI)

D D – designates footprint (50=5mm x 5mm)

E– designates binning

In the remainder of this document the term LUXEON emitter refers to any LUXEON

MultiColor Module 2.5W product as listed above.

Table of Contents

Introduction ...........................................................................1

Scope.................................................................................1

1. Component ........................................................................3

1.1 Description ..........................................................................3

1.2 Optical Raysets ......................................................................3

1.3 Handling Precautions .................................................................3

1.4 Cleaning ............................................................................4

1.5 Electrical Isolation ....................................................................4

1.6 Mechanical Files......................................................................4

2. PCB Design Guidelines for the LUXEON Emitter .........................................4

2.1 PCB Footprint and Land Pattern .......................................................4

2.2 Solder Mask .........................................................................5

2.3 Surface Finishing .....................................................................5

2.4 Minimum Spacing ....................................................................6

2.5 PCB Quality and Supplier..............................................................6

3. Thermal Management ...............................................................6

4. Thermal Measurement Guidelines.....................................................6

5. Assembly Process Guidelines .........................................................6

5.1 Stencil Design........................................................................6

5.2 Solder Paste .........................................................................6

5.3 Solder Reow Prole..................................................................6

5.4 Pick and Place .......................................................................7

5.5 Electrostatic Discharge Protection ......................................................8

5.6 JEDEC Moisture Sensitivity .............................................................8

6. Packaging Considerations—Chemical Compatibility ......................................9

1. Component

1.1 Description

The LUXEON MultiColor Module 2.5W emitter (Figure 1) is a plastic molded lead-frame package with four anode pads, four

cathode pads, and an electrically active thermal pad. The center thermal pad (pin 9) is electrically connected to the anode

of Red LED (pin 3), as shown in Figure 1 below. A chamfer on the corner of the package marks the cathode side of the

emitter package. The light emitting surface (LES) is encapsulated with silicone to protect the chips. The LUXEON MultiColor

Module 2.5W package is ESD HBM rated at ≥2kV (Class 2, JEDEC 22A-114) and does not include a transient voltage

suppressor (TVS) chip.

Mechanical center

of package

Figure 1. Mechanical Drawing of LUXEON MultiColor Module 2.5W.

1.2 Optical Raysets

Please see the optical rayset data and readme le for the reference point and optical center of each LED in the LUXEON

MultiColor Module 2.5W emitter. Optical rayset data for the LUXEON emitter are available 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 aect 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 (Figure 2).

Figure 2. Illustration example of correct handling (left) and incorrect handling (right) of a representative LUXEON emitter.

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, rst 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 minimum creepage distance within the LUXEON MultiColor Module 2.5W is 0.5mm between pads of dierent electrical

potential. It is important to keep sucient 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, ashover 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).

1.6 Mechanical Files

Mechanical drawing (3D STEP) for LUXEON MultiColor Module 2.5W is available on the website at lumileds.com.

2. 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.

2.1 PCB Footprint and Land Pattern

An example PCB footprint design for the LUXEON emitter is shown in Figure 3a. Dimensions of the footprint design are

shown in Figures 3b and 3c. In order to ensure proper heat dissipation to the PCB, it is best to extend the top copper

layer of the center thermal pad beyond the perimeter of the LUXEON emitter as much as possible (see Section 3). In

Figures 3a-c, the thermal pad is connected to the anode of the Red LED.

Figure 3a. Example PCB footprint design for LUXEON MultiColor Module 2.5W.

Figure 3b. Overall dimensions of example PCB footprint design for LUXEON MultiColor Module 2.5W. Dimensions in mm.

Figure 3c. Recommended PCB solder pad layout for LUXEON MultiColor Module 2.5W.

2.2 Solder Mask

A stable white solder mask nish (typically a polymer compound with inert reective ller) with high reectivity in the

visible spectrum will typically meet most application needs. The white nish should not discolor over time when exposed

to elevated operating temperatures. Customers are encouraged to work with their PCB suppliers to determine the most

suitable solder mask options which can meet their application needs.

2.3 Surface Finishing

Lumileds recommends using a high temperature organic solderability preservative (OSP) or electroless nickel immersion

gold (ENIG) plating on the exposed copper pads.

2.4 Minimum Spacing

Lumileds proposes 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.

2.5 PCB Quality and Supplier

Select PCB suppliers that are capable of delivering the required level of quality. At a minimum the PCBs must comply with

IPC standard (IPC-A-600H, 2010 “Acceptability of Printed Boards”).

3. Thermal Management

The overall thermal resistance between a LUXEON emitter and the heat sink is strongly aected by the design and material

of the PCB on which the emitter is soldered. Al-MCPCBs have been historically used in the LED industry for their low

thermal resistance and rigidity.

4. Thermal Measurement Guidelines

The typical thermal resistance Rθj-substrate between the junction and the substrate of the LUXEON emitters are provided in

the datasheet. The Rθj-substrate was measured with each LED on by itself. These values are listed in Table 1 below.

Table 1. Typical thermal resistance from junction to substrate of LUXEON MultiColor Module 2.5W.

MODEL RECOMMENDED RθJ-SUBSTRATE [K/W]

LUXEON MultiColor Module 2.5W Blue 25

LUXEON MultiColor Module 2.5W Red 20

LUXEON MultiColor Module 2.5W Green 55

LUXEON MultiColor Module 2.5W White 28

5. Assembly Process Guidelines

5.1 Stencil Design

The recommended solder stencil thickness is 5 mils (127μm).

5.2 Solder Paste

Lumileds recommends lead-free solder for the LUXEON emitter. Good results have been obtained with lead-free solders

such as SAC 305 solder paste from Alpha Metals (SAC305-CVP390-M20 type 3). 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.

5.3 Solder Reow Prole

The LUXEON emitter is compatible with standard surface-mount and lead-free reow technologies. This greatly simplies

the manufacturing process by eliminating the need for adhesives and epoxies. The reow step itself is the most critical

step in the reow 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 prole throughout the reow process

must be well maintained.

A temperature prole consists of three primary phases:

1. Preheat: the board enters the reow oven and is warmed up to a temperature lower than the melting point of the

solder alloy.

2. Reow: 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.

5.4 Pick and Place

The LUXEON emitter is packaged and shipped in tape-and-reel which is compatible with standard automated pick-and

place equipment to ensure the best placement accuracy. Note that pick and place nozzles are customer specic and are

typically machined to t specic pick and place tools. Lumileds advises customer to take the following general pick and

place guidelines into account:

a. The nozzle tip should be clean and free of any particles since it may interact with the top surface of the silicone

encapsulation of the LUXEON emitter package.

b. During setup and the rst initial production runs, it is a good practice to inspect the top surface of the LUXEON

emitters after reow under a microscope to ensure that the emitters are not accidentally damaged by the pick

and place nozzle.

An evaluated nozzle is shown in Figure 4. This Panasonic 140 Nozzle was tested using the Panasonic NPM-W2 machine.

Please run your own tests to evaluate other nozzles.

Figure 4. Example of tested nozzle: Panasonic 140 Nozzle.

5.5 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 (leaky diode). It is also important to take

note that ESD can also cause latent failure, i.e. failure or symptoms as described above may not show up immediately but

until after use. Hence continuous ESD protection is needed during assembly.

5.6 JEDEC Moisture Sensitivity

The JEDEC Moisture sensitivity level (MSL) for this LUXEON emitter is rated as level 3. Proper storage, handling and/or

baking guidelines must be observed to prevent damage to the LUXEON emitter during reow (see Table 2).

Table 2. JEDEC Moisture sensitivity levels for LUXEON MultiColor Module 2.5W.

LEVEL

FLOOR LIFE SOAK REQUIREMENTS STANDARD

TIME CONDITIONS TIME CONDITIONS

3 168 Hours ≤30°C / 60% RH 192 Hours +5/-0 30°C / 60% RH

6. 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 diuse into the silicone overcoat. VOCs may originate from adhesives, solder uxes, 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 diuse into the silicone and oxidize during the presence of heat or

light. Regardless of the physical mechanism, both cases may aect the total LED light output. Since silicone permeability

increases with temperature, more VOCs may diuse 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 ux 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 ow). Transferring the devices which were discolored in the enclosed

environment back to “open” air may allow the oxidized VOCs to diuse 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 dicult 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 3 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

aect LED performance.

The chemicals in Table 3 are typically not directly used in the nal 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 suciently 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 xture

under High Temperature over Life (HTOL) conditions.

Table 3. 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

Acetic Acid Acid

Hydrochloric Acid Acid

Nitric Acid Acid

Sulfuric Acid Acid

Ammonia Alkali

Potassium Hydroxide Alkali

Sodium Hydroxide Alkali

Acetone Solvent

Benzene Solvent

Dichloromethane Solvent

Gasoline Solvent

MEK (Methyl Ethly Ketone) Solvent

MIBK (Methyl Isobutyl Ketone) Solvent

Mineral Spirits (Turpentine) Solvent

Tetracholorometane Solvent

Toluene Solvent

Xylene 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 [1]

Acrylic Tape Adhesive

Cyanoacrylate Adhesive

Note for Table 3:

1. Other than the use of no-clean solder paste qualied by customer. Avoid secondary solder ux, for example when manually soldering wires close to LUXEON emitter, the solder ux

should not spit onto the LUXEON emitter surface or leaving excessive secondary solder ux residue onto the PCB when operating LEDs in an air tight enclosure or poorly ventilated

enclosure.

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