Ceramic Printed Circuit Boards (PCBs) offer a higher performance when place side-by-side with traditional PCBs. The boards also comprise ceramics as the base material, with the inclusion of the connection and circuit layers.
Although these circuit boards don’t use insulation layers, they tend to manage heat dissipation effectively. In this article, you will discover the top five (5) ceramic PCB manufacturing processes.
What are these Ceramic PCB Manufacturing Processes?
These are the distinct methods of manufacturing of producing the ceramic circuit boards. Each method differs, and the targeted applications tend to differ too.
One fact about these ceramic PCB manufacturing processes is that utilize a minimalized Expansion Coefficient (CTE) and combines the same with the improved thermal performance to bolster the overall functionality of the devices.
Now, we are going to dig deeper into the different types of manufacturing processes for making a ceramic Printed Circuit Board (PCB).
1. High Temperature Co-Fired Ceramic (HTCC)
As the name suggests, it is primarily used for ceramic applications requiring higher temperatures. The estimated temperature value or rating can be anywhere between 1600 and 1700-degree Celsius.
Required Materials
The list of materials required to make the HTCC ceramic circuit boards includes:
- Lubricant
- Solvent
- Adhesive
- Plasticizer
- Aluminum oxide
Pre-Requirements
There is no need to add the glass when making the earliest preparations for the HTCC. You only need to sinter and dry the ceramic powder ahead of the creation of the raw materials.
Note that you may need to drill holes on specific parts of the substrate board, only if you are looking to pass the materials through the holes.
Form the Raw Materials
You can now start the process of forming the raw materials for the ceramic PCB. The combination of rolling and continuous checking will be needed until the coating comes out as expected.
Next, you want to apply the circuit tracing using either the tungsten or molybdenum metals. Have in mind also that the metal paste or circuit tracing can be interchanged to other forms of refractory metals, such as manganese. Also, the metal must be printed in the same pattern as the designs made on the holes. This will help create or form a circuit layer on the circuit board’s substrate.
Bake the Materials
You now need to bake the raw materials with a temperature ranging between 1600 and 1700-degree Celsius.
Allow the mixture to bake for at least 32 hours, though it can be as much as 48 hours, depending on the expected lamination.
Take Note of Oxidation
You want to do all you can to prevent the metals from being overly exposed to a high temperature, which could lead to oxidation.
To that end, consider using low or reduced gas for the baking. Examples of the gases to use are:
- Mixed gas or;
- Hydrogen
2. Low Temperature Ceramic (LTCC) PCB Manufacturing Process
It is the opposite of the HTCC because it uses lower temperatures for the baking. Ceramic circuit boards manufactured with the LTCC manufacturing process require the combination of crystal glass and adhesive substance.
Apply the Base Materials
The base materials for the manufacturing are the adhesive substance and the crystal glass. They are to be applied to a metal sheet that has gold paste.
The gold paste also comes in handy when applying circuit tracing. The next step after this would be to cut and laminate these materials.
Baking
Once the materials are cut and laminated, they are to be placed over an oxidized gas oven and baked at a temperature of 900-degree Celsius, maximum.
Circuit Protection
After the baking, it must be protected by using the solder mask. Note that the processes involved here can also be further optimized to include shrink tolerance and less warpage.
3. Thick Film Ceramic PCB Manufacturing Process
This is the third most-significant process of manufacturing ceramic Printed Circuit Boards (PCBs).
One of the attributes of the ceramic circuit boards is that they help to reduce the costs of working with ceramic PCB materials, thanks to the affordability. Thick film ceramic PCBs also help to prevent the copper from oxidizing during and after the manufacturing process.
Here are the steps involved in manufacturing thick film PCBs:
Preparation
Before any other thing, the ceramic substrate where the components or materials are to be placed will be cleaned.
Next, you want to thermally evaporate the ceramic substrate. It is important to do this if you are looking to work on the board in vacuum conditions.
Print the Layers and Images
The next step would be the formation of the copper layer by using magnetron sputtering on the substrate’s surface. After this, you would use the yellow-light photoresist technology to form the circuit image on the copper layer.
Note that the gold and dielectric pastes will also be implemented on the base material of the ceramic circuit board.
Bake the Materials
Place the pastes and the additional components in the package in a nitrogen-enabled gas. It helps to prevent the copper from being oxidized. We also want to mention that excess copper can be removed by using etching.
The last step would be the application of the solder mask to protect the thick film ceramic PCB.
Direct Plated Copper (DPC)
Although this is not as popular as the other types of ceramic PCB manufacturing processes, it is still relevant. The DPC manufacturing method shares some similarities with the Thick Film method, with the main similarity being the printing of the circuit image atop the copper film.
The additional manufacturing processes for the Direct Plated Copper include:
- Adding the copper thickness via plating.
- Several process links, such as etching, development and vacuum coating. Wet coating and exposure are also included.
- The copper film would later be removed after the circuit image printing, and is to be followed by the solder masking for circuit protection.
4. Direct Bonded Copper (DBC)
The primary ceramic PCB manufacturing process used here is “bonding” or making a direct placement of the copper plate to the ceramic substrate. A temperature of 1065 and 1083-degree Celsius must be used for this.
Afterwards, the following manufacturing processes would follow suit:
- The formation of an alloy between the ceramic substrate and the copper foil.
- Maintaining between 150 and 300 microns to bolster the thickness of the copper foil.
- Etching the copper layer on the copper-clad.
- Laminating the layers only on the condition that multiple layers were used.
- Protecting the circuit design with a solder mask.
Conclusion
Each of the ceramic PCB manufacturing processes discussed in this article has different manufacturing designs and the outcome is always targeted at improving the circuit board’s performance. Contact a professional ceramic PCB digital designer to help you with next set of electronic projects you want to get done.