Introduction
You do not need a complete LED module specification before contacting a manufacturer.
Some OEM customers begin with detailed drawings, electrical requirements, and an existing PCB design. Others may only have a finished product, an old LED board, a mechanical envelope, or a target light output.
Both situations can be valid starting points.
What matters is identifying the information already known, understanding which requirements still need to be defined, and translating the product's needs into a practical LED module design.
A good LED module specification connects several areas:
- Mechanical dimensions
- Electrical architecture
- Optical performance
- PCB construction
- Thermal conditions
- Connectors and wiring
- Dimming or control
- Environmental requirements
- Testing expectations
- Production volume
These requirements are interconnected. Changing one can affect several others.
This guide explains what OEM teams should provide when requesting a custom LED module—and what can be determined together during engineering development.
1. Start With the Application
Before discussing PCB material, LED package, or operating current, the first question should be:
What is the LED module being designed for?
The intended application provides important context for almost every engineering decision that follows.
Examples may include:
- Commercial lighting
- Industrial equipment
- Architectural products
- Vehicle lighting
- Marine equipment
- Display systems
- Specialty lighting
- Medical or laboratory equipment
- Other OEM products
An LED module used inside an enclosed industrial machine may have very different requirements from a module installed in a commercial luminaire.
Application information helps the engineering team understand the environment in which the module needs to operate.
2. Provide the Available Mechanical Dimensions
For many custom projects, mechanical constraints are among the first fixed requirements.
Useful information includes:
- Maximum PCB length
- Maximum PCB width
- PCB shape
- PCB thickness
- Mounting-hole locations
- Hole diameters
- Connector position
- LED positions
- Keep-out areas
- Housing dimensions
The PCB may be:
- Round
- Square
- Rectangular
- Linear
- Ring-shaped
- Irregularly shaped
If a mechanical drawing is available, it can significantly reduce ambiguity.
Common formats may include PDF drawings, CAD files, dimensioned sketches, or an existing physical sample.
However, a professional CAD drawing is not always required to begin the discussion.
A clear sketch with critical dimensions can often provide enough information for an initial engineering review.
3. Tell Us Whether You Have an Existing LED Module
Not every custom LED module project starts from zero.
An OEM customer may already have:
- An existing LED PCB
- A discontinued module
- A competitor's module that needs replacement
- A previous-generation design
- A prototype
- A finished product containing the existing board
In these cases, the existing module can provide valuable information about:
- PCB dimensions
- Mounting points
- Connector location
- LED layout
- Circuit architecture
- Power requirements
- Mechanical interfaces
The goal does not necessarily need to be an exact copy.
The existing module can serve as a reference while electrical, optical, thermal, or manufacturing aspects are redesigned according to the new project requirements.
4. Define the Input Voltage or Driver
One of the most important electrical requirements is how the LED module will be powered.
If the product already has a driver or power supply, provide its specifications whenever possible.
Useful information may include:
- Constant current or constant voltage
- Output current
- Output voltage range
- Nominal DC voltage
- Maximum power
- Dimming method
- Driver model
- Driver datasheet
For example, simply stating:
“The product uses a 20 W driver”
may not provide enough information.
A constant-current driver also needs an appropriate output-current rating and voltage range.
A constant-voltage system requires the LED module to be designed for the intended supply voltage and current-control architecture.
For more information, see Constant Current vs Constant Voltage LED Modules: Which Should You Choose?
5. Specify the Target Power When Known
If the required module power is already defined, include it in the project information.
Examples might include:
- 5 W
- 10 W
- 20 W
- 30 W
- Application-specific power levels
However, power should not be treated independently from the required light output and thermal environment.
Two LED modules with the same wattage can have very different:
- Lumen output
- Efficacy
- PCB dimensions
- LED quantity
- Power density
- Operating temperature
If the target lumen output is more important than a fixed wattage, it can be better to communicate that requirement directly.
6. Define the Required Light Output
For lighting applications, target luminous flux is often one of the main performance requirements.
If known, provide the desired lumen output.
But it is also important to clarify where that lumen requirement applies.
For example:
- LED module output
- Output after diffuser
- Complete luminaire output
- Finished product output
These values may not be the same because optical components introduce losses.
A diffuser, lens, reflector, light guide, or cover can reduce the amount of light leaving the finished product.
If the final fixture needs a particular lumen output, this should be communicated so that the LED module can be designed with appropriate system losses in mind.
7. Specify CCT
For white-light LED modules, provide the required correlated color temperature when known.
Common options include:
- 2700K
- 3000K
- 3500K
- 4000K
- 5000K
- 5700K
- 6500K
Some OEM products may require multiple CCT versions.
Others may require tunable white operation across a defined CCT range.
If color consistency is particularly important, this should also be included in the specification.
8. Specify CRI
CRI requirements should be based on the application.
Common specifications include:
- CRI 70+
- CRI 80+
- CRI 90+
- CRI 95+
A higher CRI is not automatically necessary for every product.
The correct specification depends on the importance of color rendering, efficacy, application requirements, and product positioning.
For a more detailed explanation of CCT, CRI, and efficacy, see Understanding CCT, CRI and Luminous Efficacy in LED Module Design.
9. Do You Need a Specific LED Brand?
If the project requires a particular LED manufacturer or part number, provide that information.
There are several reasons an OEM customer may specify an LED:
- Existing product qualification
- Customer requirement
- Optical consistency
- Approved vendor requirements
- Existing certification documentation
- Compatibility with previous production
However, an exact LED part number is not always necessary.
If the requirement is performance-based, the specification can instead define:
- Lumen output
- CCT
- CRI
- Efficacy target
- Color consistency
- Electrical requirements
- Reliability expectations
An appropriate LED can then be selected as part of the engineering process.
For more information, see How to Select LEDs for a Custom LED Module.
10. Define the PCB Size and Material Requirements
If PCB material has already been specified, include it in the RFQ.
Common LED module PCB constructions include:
- FR4
- Aluminum PCB
However, if you are unsure which material is appropriate, it does not need to be decided before the project begins.
PCB selection depends on factors such as:
- Power density
- Thermal path
- Circuit complexity
- PCB dimensions
- Housing design
- Electrical requirements
- Cost
For many thermally demanding LED applications, aluminum PCB can provide an effective path for transferring heat toward the housing or heatsink.
FR4 may be appropriate for other applications, particularly when power density is moderate or the circuit requires greater electronic complexity.
For a detailed comparison, see FR4 vs Aluminum PCB for LED Modules: How to Choose.
11. Describe the Thermal Environment
One of the most useful pieces of information for LED module design is how the PCB will be mounted and cooled in the finished product.
Tell the engineering team whether the LED module will be installed on:
- Aluminum housing
- Dedicated heatsink
- Metal plate
- Plastic structure
- Enclosed compartment
- Open-air assembly
- Other mounting surface
Also provide expected ambient temperature when known.
If thermal interface material will be used between the PCB and housing, that information is also useful.
An LED module cannot be thermally evaluated correctly by PCB wattage alone.
The entire path from the LEDs to the surrounding environment needs to be considered.
See LED Module Thermal Management: Design Considerations for Long-Term Reliability.
12. Provide Connector and Wiring Requirements
Connectors are easy to overlook during early development, but they can become important mechanical and production constraints.
Useful information includes:
- Connector manufacturer
- Connector series
- Exact part number
- Wire length
- Wire gauge
- Wire color
- Polarity
- Connector orientation
- Cable exit direction
- Solder-pad requirements
If the customer already has a mating connector in the finished product, the exact connector information should be provided.
If no connector has been selected, the requirements can be evaluated during module development.
13. Define Dimming and Control Requirements
If the LED module needs more than simple on/off operation, describe the control requirements early.
Examples may include:
- PWM dimming
- Analog dimming
- Tunable white
- RGB
- RGBW
- Multiple independent LED channels
- Sensor integration
- Other control functions
These requirements can influence:
- Circuit architecture
- Connector pin count
- LED selection
- Driver selection
- PCB layout
- Testing
Adding multi-channel control after the PCB architecture has already been finalized can require significant redesign.
For specialty systems, see NKT's Specialty OEM LED Module Applications.
14. Explain the Optical System
If the LED module operates behind optical components, provide as much information as possible about them.
These may include:
- Diffuser
- Lens
- Reflector
- Light guide
- Cover
- Mixing chamber
The distance between the LEDs and optical components can also be important.
LED quantity and spacing influence visual uniformity.
A PCB that produces acceptable light distribution in open air may behave differently after being placed behind a shallow diffuser.
If the optical system already exists, physical samples or mechanical drawings can be particularly useful during prototype evaluation.
15. Describe the Operating Environment
The intended environment can affect component selection, PCB design, testing, and protection requirements.
Relevant conditions may include:
- Indoor or outdoor use
- High ambient temperature
- Low temperature
- High humidity
- Vibration
- Mechanical shock
- Vehicle electrical environment
- Marine environment
- Corrosive atmosphere
- Long operating hours
It is important to communicate actual application requirements rather than simply requesting the most rugged possible design.
Different environmental requirements can lead to different engineering and cost decisions.
For demanding vehicle and equipment applications, see NKT's Heavy-Duty & Marine LED Module Applications.
16. Clarify IP Rating Requirements
An important distinction needs to be made when discussing IP ratings.
An exposed LED PCB does not automatically receive the same IP rating as the finished product.
Ingress protection often depends on:
- Enclosure
- Gaskets
- Sealing
- Connectors
- Cable entries
- Mechanical assembly
If the complete product requires an IP rating, tell the LED module manufacturer how the PCB is integrated into that product.
If the module itself requires additional protection, possible approaches can be evaluated according to the application.
The requirement should be defined at the correct assembly level.
17. Provide Expected Production Quantity
Production volume is not only a purchasing question.
It can influence engineering and manufacturing decisions.
Useful information includes:
- Prototype quantity
- Initial production quantity
- Estimated annual volume
- Expected project lifetime
A project requiring 100 modules per year may justify different manufacturing decisions from one requiring tens of thousands.
Expected volume can influence:
- Component sourcing
- PCB panelization
- Tooling decisions
- Connector selection
- Test fixtures
- Production testing
- Cost optimization
An approximate forecast is usually sufficient during early development.
18. Define Testing or Validation Requirements
If your company has specific testing requirements, provide them during the development stage.
These may include:
- Electrical testing
- Optical testing
- Thermal testing
- Functional testing
- Aging or burn-in
- Environmental testing
- Application-specific validation
Testing requirements should be aligned with the intended application.
Not every module requires the same validation plan.
For more information, see LED Module Testing and Quality Control: What OEM Customers Should Know.
19. Provide Certification Requirements When Relevant
Certification requirements often apply to the finished product or complete electrical system rather than to the bare LED PCB alone.
However, they can still influence module design.
If the finished product is intended for a particular certification or market requirement, communicate this early.
Relevant information may include:
- Target market
- Product certification requirements
- Material restrictions
- Customer-specific compliance requirements
This allows the module design and component selection to be evaluated within the larger product-development context.
20. Send Existing Files and Samples
You do not need to convert everything into a formal specification document before requesting a quote.
Useful project materials can include:
- PCB drawings
- Gerber files
- BOM
- Schematics
- Mechanical drawings
- CAD files
- Driver datasheets
- LED datasheets
- Photos
- Existing samples
- Finished product samples
- Hand sketches with dimensions
Even partial information can help establish the starting point.
The engineering process can then identify what is still missing.
What If You Do Not Know All the Specifications?
This is common.
An OEM customer may know:
“We need a round LED board that fits inside this housing and produces approximately 1,500 lumens.”
but may not yet know:
- Which LED package to use
- How many LEDs are required
- What operating current is appropriate
- Whether FR4 or aluminum PCB should be used
- Which driver is best
- How the thermal path should be designed
That does not prevent the project from starting.
The purpose of engineering development is to turn product-level requirements into a practical technical solution.
If you already knew every LED, PCB, circuit, and thermal detail, much of the engineering work would already be finished.
For an overview of this process, see Custom LED Module Design: From Concept to Production.
A Practical Custom LED Module RFQ Checklist
When contacting an LED module manufacturer, provide as many of the following items as you already know:
- Application
- PCB dimensions and shape
- Mechanical drawing
- Input voltage
- Constant-current or constant-voltage architecture
- Driver specification
- Target power
- Target lumen output
- CCT
- CRI
- Color consistency requirements
- Preferred LED brand, if required
- PCB material, if already defined
- Connector requirements
- Dimming or control requirements
- Housing or heatsink information
- Expected ambient temperature
- Environmental requirements
- Optical components
- Testing requirements
- Certification requirements
- Prototype quantity
- Estimated production volume
- Existing PCB, sample, or product reference
You do not need every item before contacting NKT.
Provide what is known, and clearly identify what still needs to be determined.
That gives the engineering team a much better starting point than trying to guess specifications that have not yet been defined.
What Happens After You Submit the Requirements?
A custom LED module project typically progresses through several stages.
Application and requirement review
→ Engineering evaluation
→ Initial module concept
→ PCB and circuit design
→ Component selection
→ Prototype production
→ Electrical, optical, and thermal evaluation
→ Customer validation
→ Design adjustment if required
→ Final approval
→ Production
The exact sequence depends on the project.
Some replacement-module projects can be relatively straightforward.
A completely new LED system involving custom mechanics, optics, thermal requirements, and electronic controls may require more development.
The important point is that the module should be developed as part of the complete product rather than as an isolated PCB.
Common RFQ Mistakes
Providing Only Wattage
Wattage does not define the required light output, electrical architecture, PCB size, or thermal conditions.
Providing Only PCB Dimensions
Mechanical dimensions are important, but electrical and optical requirements are also needed.
Selecting LEDs Before Defining the Application
The highest-output or highest-efficacy LED is not automatically the correct choice for the finished product.
Ignoring the Driver
The LED module and driver need to operate as a compatible electrical system.
Ignoring the Housing During Thermal Design
The mechanical structure often forms part of the module's thermal path.
Waiting Until the End to Discuss Production Volume
Expected volume can influence component selection and manufacturing decisions from the beginning.
Frequently Asked Questions
Do I need a complete drawing to request a custom LED module?
No. A detailed mechanical drawing is useful, but a project can often begin with dimensions, photos, sketches, an existing PCB, or a finished-product sample. Additional information can be developed during engineering review.
Can NKT redesign an existing LED PCB?
Yes, an existing PCB can serve as the starting point for a custom project. Depending on the requirements, dimensions, LED selection, circuit architecture, PCB material, connector, thermal design, or other elements may be evaluated.
Do I need to specify the LED brand?
Not necessarily. If a particular LED manufacturer or part number is required, include it in the specification. Otherwise, performance requirements can be used to evaluate suitable LED options.
Should I specify lumens or watts?
Ideally provide both when they are known. If the finished product has a required light output, lumen requirements can be particularly important because wattage alone does not define optical performance.
What if I do not know whether I need constant current or constant voltage?
Provide information about the existing power supply, driver, product architecture, and electrical requirements. The appropriate module architecture can then be evaluated during engineering development.
How many units do I need for a custom LED module project?
Prototype and production quantities depend on the project. Providing the expected prototype requirement and estimated annual production volume helps determine an appropriate development and manufacturing approach.
Ready to Discuss Your Custom LED Module?
You do not need to complete every technical decision before contacting NKT.
If you have a product concept, existing LED board, mechanical drawing, driver specification, sample, or simply a set of target performance requirements, send us the information you already have.
NKT can support OEM LED module projects from engineering evaluation and PCB design through LED selection, prototyping, testing, and production.