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Ultimate Guide to COB LED Manufacturing - Done at One-Stop Now

PCBONLINE Team Tues, Jul 27, 2021

COB LED module

What do you know about COB LEDs? You may say, that now all spotlights are COB LEDs. And you may also say, COB LED lights are manufactured by grouping many light-emitting diodes on a circuit board. Here is a more specific explanation of COB LEDs:

COB, or chip on board, is an LED packaging technology to directly bond/attach multiple LED chips on a printed circuit board. The chips are covered and sealed in thermally conductive epoxy resin (usually adding silver). The printed circuit boards used for COB LED modules are usually ceramic PCBs. Sometimes, the circuit boards can be copper substrate PCBs and aluminum substrate PCBs.

The essence of a COB LED module is a PCBA. But the components - LED chips are so tiny, and they are assembled on the PCBs by operators with the help of the microscope. The chips are fragile from heat, moisture, and dust, so they are protected by sealing in the thermally conductive epoxy resin.

Compared with the SMD LED lights, COB LEDs have these advantages:

  • A COB LED light's luminous efficacy can reach 80Lm/W;
  • COB LEDs have multiple color temperature options and a high color rendering index;
  • COB LEDs have a uniform and soft light emission, with no ghosting/flaring.

Now you know what an LED COB is and its benefits. As an engineer or solutions company, you may want to develop your brand of LED COB lights. You may also want to know how LED COBs are manufactured.

PCBONLINE, a one-stop COB LED manufacturer, will guide you through the complete manufacturing process of COB LED modules. Let's go!

COB LED Manufacturing Process

  • Step 1: ceramic PCB manufacturing

The first step is to manufacture the substrate boards for LED packaging. Ceramic PCBs are often the PCB option for COB LEDs because alumina and aluminum nitride have good thermal conductivity and do not need an electric insulation layer. PCBONLINE manufactures ceramic PCBs, aluminum PCBs, and copper substrate PCBs according to clients' designs. PCBONLINE uses DPC technology to manufacture ceramic PCBs that can achieve 3D design for high-power LED packaging.

  • Step 2: expanding the LED chip film

The LED chips are arranged on a film. Technicians evenly expand the LED chip film to separate them using the expansion machine.

Integrated circuits are in short supply in the world. Buy LED chips and ICs before you have the COB LEDs manufactured. If you can purchase LED chips/ICs at a lower price than PCBONLINE does, purchase them.
  • Step 3: doping silver paste on the PCB pads

Like solder paste printing in the SMD production process, silver paste is applied on the PCB pads. The only difference is that there is no need for a PCB stencil, and the silver paste is doped on the PCB pads using a dispensing machine.

  • Step 4: LED chips pick and place

The LED chips are microchips, and assembling them on the PCBs is operated under the microscope. PCBONLINE's experienced operators pick and place the LED chips on the PCB pads using a die bonder.

  • Step 5: PCBA baking

This step is similar to reflow soldering in the SMT assembly process. The assembled printed circuit board is baked in a thermal cycle oven to melt and solidify the silver paste. In this way, the LED chips are attached to PCB pads tightly. When the solder paste solidifies, take the PCBA out.

  • Step 6: die bonding

If the COB LEDs have ICs (dies) that need assembling, this step and step 7 happen. Operators use the dispensing machine to dispense red or black glue on the IC pads and use anti-static equipment (vacuum suction pen or sub) to pick and place the dies on the glue.

  • Step 7: baking

Put the PCBA assembled with IC dies in the thermal cycle oven to bake. The glue melts to connect the ICs with the circuit board. When the glue solidifies, take the PCBA out.

  • Step 8: wire bonding

    gold wire bonding

Operators at PCBONLINE use gold wire or aluminum wire to connect the PCB pads by the wire bonding machine.

Another connecting method is the flip-chip (pad to pad). This method requires no gold/aluminum wires to connect the PCB pads.
  • Step 9: pre-testing

The COB LEDs can't be repaired once sealed with glue. So before sealing, technicians test the electrical characteristics of the PCBAs. Only the qualified PCBAs can enter the next step. The not-good PCBAs are returned to fix.

  • Step 10: glue sealing


LED chips are sealed with AB glue, and IC dies are sealed with black glue. And then PCBONLINE finished the appearance packaging according to customers' requirements.

  • Step 11: glue solidifying

The PCBA covered with glue is placed in the thermal cycle oven to bake again to dry up the glue.

  • Step 12: post-testing

Finally, the COB LED is assembled. Technicians at PCBONLINE test the electrical performance of the COB LED to check whether it is qualified.

Voila! The COB LEDs are manufactured. You may find that the whole production process is similar to turnkey PCB manufacturing. Yes, they are!

After the testing, PCBONLINE can adjust the RGB (green, red, and blue) LEDs' color according to the client's requirements.

Looking for Custom High-Quality COB LED Manufacturing?

flip-chip LED COB

Are you developing a COB LED project? Want a one-stop COB LED manufacturing solution? PCBONLINE, a turnkey COB LED PCB manufacturer, provides you with a one-stop COB LED manufacturing solution. PCBONLINE has decades of manufacturing experience in ceramic, aluminum, and copper substrate PCBs. It has complete COB LED production lines to complete the above steps.

      The COB LED manufacturer PCBONLINE has competitiveness for:

    • One-stop COB LED manufacturing, from 3D ceramic PCBs fabrication, chip sourcing, and PCB assembly, to the COB LED box build assembly.
    • PCBONLINE has mature techniques of COB LED wire bonding and flip-chip assembly.
    • PCBONLINE can adjust the LED light wavelength according to the specified optical parameters.
    • Apart from LED chips, PCBONLINE can also assemble capacitors, resistors, and control modules to extend LED lights' smart functions.
    • Free one-on-one engineering support (DFX) and customer service for COB LED projects.
    • PCB manufacturing is IPC-A-600 compliant, and COB LED assembly is IPC-A-610 Class 3 compliant.

The one-stop COB LED solution provider PCBONLINE can manufacture the COB on rigid and flexible substrate boards. If you are looking for COB LED manufacturing for your brand, PCBONLINE can provide one-stop contract manufacturing and co-R&D with you!

flexible COB LED

Online register and get $100 coupons for COB LED manufacturing online purchases now!

A Showcase of the COB LED Module

COB LED module

This COB LED module produced by PCBONLINE is used for spotlights. The module has a composite structure: its bottom layer is a copper substrate PCB; the white part is an embedded ceramic substrate light-emitting module; the yellow part is a light source (manufactured in the flip-chip method).


This article tells what a COB LED is and its advantages. It mainly illustrates the complete steps of COB LED manufacturing. If you want to develop COB LEDs in your brand, PCBONLINE will provide you with a one-stop COB LED manufacturing solution.


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