This article will introduce the ceramic PCB manufacturing process. Ceramic printed circuit board (PCB) is an advanced material widely used in the electronics industry, combining ceramic materials’ advantages with traditional PCBs’ functions.
Ceramic PCBs have excellent thermal conductivity, electrical insulation, and corrosion resistance, making them ideal for high-temperature, high-frequency, and high-power applications. In this article, we will take an in-depth look at the manufacturing process of ceramic PCBs.
Step 1: The Design
First, come up with the design for the ceramic PCB. You can achieve this using design software. Trace width calculator helps you in coming up with the details for the inner and the outer layers of the board.
Step 2: Printing the Design
Use a plotter printer to print the design of the PCB on the board. This will produce a film which gives the details of the layers.
Step 3: Creating the Substrate
Pass the substrate through an oven to semi-cure it. This will pre-bond copper to both sides of the layer. This will later be etched away to reveal the design of the printed films.
Step 4: Printing of inner layers
Mount a photo-sensitive film made from photoreactive chemicals. This will harden when exposed to ultraviolet light. In so doing, the blueprints will be aligned to the actual print of the board.
Step 5: Ultraviolet Light
After aligning the resist and the laminate, take the board through ultraviolet light. This hardens the photoresist.
Wash the board with an alkaline solution to clean the unwanted copper, leaving the hardened photoresist intact.
Step 6: Layer-up and Bond
The layers await their fusion at this stage. The outer layers are usually joined together with the substrate. This process takes two steps: layering up and bonding.
The outer layer materials consist of the substrates covered with thin aluminum foil on the top and bottom of the substrate. This substrate also contains copper tracing.
Now, this is the time to bond the layers together. You do this on a heavy steel table using metal clamps.
Next, securely fit the layers into pins attached to the table. Ensure that they fit appropriately to avoid shifting during alignment.
You can then proceed to place a prepreg layer over the alignment resin.
Fit the substrate layer over the prepreg before placing the copper sheet. Then more sheets of prepreg can sit on top of the copper layer.
The stack will be completed using aluminum foil and a copper press plate. You are now ready to take it through pressing.
For pressing, you will use a press-bonding computer, which heats the stack, before it is cooled down.
Step 7: Drill
You can now bore holes into the stack board with utmost precision. Ensure that the holes are drilled to a hairs-width.
Use an X-ray locator to identify proper drill target spots.
Before you start drilling, ensure that you place the board on a buffer material under the drill target. This will help to ensure that the enacted bore is clean.
These computer-aided drills usually have air-driven spindles that turn at around 150 000 rpm. This might mislead you that the drill happens in a flash.
During the drilling process, each hole needs its special moment with the drill.
Step 8: Plating and Copper Deposition
This is where you fuse the various layers.
When you have thoroughly cleaned the panel, you can proceed to wash it using several chemical baths.
When doing the baths, the chemical deposition process will deposit a thin layer of copper on the panel’s surface. This is usually about one micron thick.
The copper will go into drilled holes generated previously.
Before this step, the inner surfaces of the holes are exposed to the substrate. The copper baths will help you in covering the walls of the holes.
Step 9: Outer Layer Imaging
In this step, you will again apply a photoresist to the panel.
Pass the prepped panel through the yellow room. The yellow lights don’t carry UV levels that can affect photoresists.
To prevent misalignment with the panel, secure the black ink transparencies.
When the panel and stencil come into contact, a generator will blast them with high UV light. This will further harden the photoresist.
You can then pass the panel through a machine that will remove the unhardened resist, which is protected by black ink opacity. In this process, you will invade the inner layers.
You should then proceed to inspect the outer plates, removing all undesired photoresists.
Step 10: Plating
Return the board to the plating room. At this point, electroplate the panel with a thin layer of copper.
The sections of the panel that you have exposed from the outer layer’s photoresist stage will receive copper electroplating.
After the copper plating baths, the next step is to conduct tin plating on the panel. This makes it possible to remove all the copper remains left during the etching stage.
Step 11: Final Etching
The desired copper is protected in this stage by removing unwanted copper that will remain below the resist layer.
You can use chemical solutions to clear the excess copper. Tin will protect the valuable copper in this stage.
From here, the conducting areas and connections are now appropriately established.
Step 12: Solder Mask Application
Before you apply the solder mask to both sides of the board, ensure that you clean the board. Cover it with epoxy solder mask ink, then expose it to UV light.
Then proceed to pass it through the solder mask ink. The portions covered will remain unhardened, ready for removal.
Pass the board through an oven. This will cure the solder mask.
Step 13: Surface Finish
To add solder-ability to your ceramic PCB, chemically plate it with either gold or silver. Most manufacturers prefer silver to gold owing to the cost.
Step 14: Silkscreen
You can then complete the board by giving it ink-jet writing on its surface. This will indicate all the important innovations of the PCB. Pass your ceramic PCB to the last coating and curing stage.
Step 15: Electrical Test
This procedure will help you to confirm the functionality of the PCB.
It will also test the board’s conformity to your original design.
Step 16: Profiling and V-Scoring
This is the last step. You will cut different boards from the panel that you have made.
You have two alternative methods to achieve this. You can use a router or a v-groove. Both ways will enable you to pop out the boards from the panel easily.
Conclusion
The ceramic PCB manufacturing process includes 16 critical steps: design, printing, creating substrate, photolithography, lamination, drilling, electroplating, removing excess copper, applying solder paste, surface treatment, silkscreen, and electrical testing. These precise processes give ceramic PCBs excellent thermal conductivity, electrical insulation, and corrosion resistance, making them ideal for high-temperature, high-frequency, and high-power applications.
