Ceramic PCB Manufacturing Process: How is Made

Ceramic PCB board

How are ceramic circuit boards made? The ceramic PCB manufacturing process differs slightly from the conventional FR4 material. Several manufacturing methods are available today, each producing a circuit board with distinct characteristics. This guide takes you through these methods, explaining what the ceramic PCB manufacturer does from start to finish.

How is Ceramic PCB Made?

A ceramic printed circuit board is made by depositing and bonding a thin, conductive pattern to a ceramic material or plate. The resulting circuit board is then either a single or multilayered type.

These two board types pass through different manufacturing stages, seeing that one requires a more detailed process than the other.

Single Layer Ceramic PCB

A single-layer ceramic PCB only requires a single substrate plate to fabricate. This type of PCB is easy to produce, costing less and requiring fewer manufacturing steps.

The single-layer PCB suits simple applications requiring only a few components and interconnections. It offers good heat dissipation and can fit high-temperature conditions.

Multilayer Ceramic PCB

A multilayer ceramic PCB requires additional steps than the multilayer type. These include depositing the conductive layers and heating processes to bond the layers together.

To electrically link the different layers, this PCB type requires the drilling of vias through its substrate. A multilayer ceramic board packs more devices and supports complex circuits. The high-density feature is often a requirement of high-end devices or systems.

Inside a PCB manufacturing factory
Inside a PCB manufacturing factory
Resource: https://www.assemblymag.com

Ceramic PCB Manufacturing Process

A ceramic PCB manufacturing process can take several routes, depending on the required board characteristics.

For example, it can be a thick or thin film board, a high or low-temperature type, etc. Here, we’ll focus on the general steps of the fabrication process. These are:

  • Design and layout
  • Substrate preparation
  • Applying the conductive layer and patterning
  • Stacking layers
  • Via drilling
  • Firing the ceramic and adding one more layer
  • Testing of the finished PCB by the QC department.

Step 1: Ceramic PCB Design and Layout

The ceramic PCB manufacturing process begins with the design phase. In this stage, a designer uses CAD software to create a 3D representation of the circuit and its components.

Essential considerations during this time include the various conductive tracks or traces, electronic component locations and their identity, vias, etc. With the design ready, the fabrication process can now begin.

Ste2: Ceramic Substrate Production

The substrate is then prepared. The substrate is the base material that will hold the circuitry and components.

The typical PCB ceramic substrate is one of these materials: alumina or aluminum oxide, aluminum nitride, beryllium oxide, or silicon carbide.

  • To make high-temperature substrates, manufacturers mix ceramic powder with organic binders and several other materials. The result is a thick paste that is later baked to evaporate the binders.
  • Low-temperature substrates have ceramic powders mixed with binders and crystal glasses, unlike the high-temperature method that uses no glass.
  • The manufactured ceramic substrates are cut and shaped into thin plates as needed.
  • If the fabrication process requires multiple layers, these are also prepared.

Step 3: Substrate Metallization and Patterning

Metallization is one of the most critical steps of the ceramic PCB manufacturing process. A layer of conductive material is applied to the substrate.

The conductive layer is commonly copper; other materials (such as gold, silver, or palladium) are standard options that manufacturers can use instead.

Various film deposition methods are employed. These are mainly categorized as thick or thin film types and are used for different ceramic PCB types.

  • In the thin film method, vacuum deposition (vaporization and sputtering) is used to apply the paste to the base material.
  • The method produces a thin conductive film (0.1 micrometers or less).
  • Using photolithography, the circuit is developed.
  • For thick film ceramic PCB, a silk screen is used to apply the paste to the substrate.
  • The substrate is heated, and the film is etched to reveal the earlier circuit.

Step 4: Layer Stacking

Sometimes, several layers are necessary depending on the board application. These are stacked together, one after the other. A PCB ceramic stack-up allows the substrate to connect different circuits in high-density applications.

The stacking process involves carefully aligning the various ceramic plates. Separation or insulation layers are also necessary. They help with ensuring the required electrical characteristics of the finished board.

Step 5: Via Drilling

In a multilayer ceramic circuit board, the different layers must connect electrically. This is to enable the passage of signals from one layer to another.

Drilling vias in a ceramic PCB is done the same way as that of other substrates. It can be a mechanical process, using physical drill bits, or without the need for mechanical force by using laser equipment.

Step 6: Firing Ceramic Substrate

The stacked ceramic PCB substrate now undergoes another final heating process. The firing is meant to heat the different layers and firmly bind them together.

The heating process produces a robust, heat-resistant circuit board that matches different application conditions.

Step 7: Final Layer Deposition

Next, the final layer of conductive material is added to the top surface. The coating makes the surface solder-able, which, in turn, will help ensure proper component assembly later on.

During this stage of the ceramic PCB process, assembly is possible, and components can be mounted. If not, the board goes to the last stages of its fabrication process.

Step 8: Testing and Inspection

The finished ceramic core PCB is taken through a series of tests. These include manual or automated optical inspections.

In addition to visual and optical inspection, different electrical testing procedures are carried out. These vary from manufacturer to manufacturer.

Any other final touches to the PCB, such as the application of a protective finish, are done. Lastly, the product is packaged and readied for delivery to the customer.

Ceramic circuit boards offer unique characteristics, making them a great alternative to common substrates such as FR4. These are:

  • Good thermal conductivity
  • Excellent mechanical strength
  • Exceptional electrical properties
  • Chemical and heat resistance
  • Great customization options, including miniaturized designs

Conclusion

The ceramic PCB manufacturing process is a detailed process that involves several distinct steps. As explained in the guide, each stage serves an important function. Different manufacturing methods also produce varying characteristics in the final circuit board, which can impact its applications. Depending on your intended use, your manufacturers can advise on the best option for your project.

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