What is Metal Core PCB?
Metal Core Printed Circuit Boards (MCPCBs) are a type of PCB that have a metal core (usually aluminum) instead of a traditional fiberglass core. MCPCBs are commonly used in applications that require high power and high thermal conductivity, such as LED lighting, power supplies, and automotive electronics. In this blog post, we will discuss the manufacturing process for MCPCBs.
Metal Core PCB Structure
The basic structure of MCPCB is composed of the following parts:
- Solder mask
- Circuit layer
- Copper layer
- Dielectric layer – prepreg (PP) / fiberglass (FR-4)
- Matel base – Aluminum, Copper, or Iron
The Metal Core PCB Manufacturing Process
The manufacturing process for MCPCBs is similar to that of traditional PCBs, but with a few additional steps. The process can be broken down into the following steps:
Step 1: Material Preparation
The first step in the manufacturing process is material preparation. This includes the metal core (usually aluminum or copper), the dielectric layer, and the copper layer. The metal core is typically pre-drilled to allow for easier placement of components. The metal core is then coated with a layer of dielectric material, which is used to insulate the metal core from the copper traces that will be added later in the process.
Step 2: Lamination
The next step is to laminate the layers together. This is done using heat and pressure to bond the layers together. The result is a single, solid piece of material.
Step 3: Drilling and Routing
After the layers are laminated together, the board is drilled and routed to create the necessary holes for components and to shape the board to the desired size and shape.
Step 4: Etching the Circuit Pattern
After the metal core has been coated with the dielectric material, the next step is to etch the circuit pattern onto the surface of the dielectric material. This is done using a photoresist material that is applied to the surface of the dielectric material. The photoresist material is then exposed to ultraviolet light, which causes it to harden in the areas where the circuit pattern will be etched.
The photoresist material is then removed from the surface of the dielectric material, leaving behind the circuit pattern. The circuit pattern is then etched into the surface of the dielectric material using an etching solution, which removes the exposed copper from the surface of the dielectric material.
Step 5: Adding Copper Traces
After the circuit pattern has been etched onto the surface of the dielectric material, the next step is to add the copper traces. This is done using a process called electroplating.
Electroplating involves immersing the board in a bath of copper sulfate solution. A positive electric charge is applied to the metal core, which attracts the negatively charged copper ions in the solution. The copper ions then attach themselves to the exposed copper traces on the surface of the board, creating a thin layer of copper.
Step 6: Solder Mask Application
The next step in the process is to apply a solder mask to the surface of the board. The solder mask is a protective layer that is applied to the surface of the board to protect the copper traces from damage during the soldering process.
The solder mask is typically applied using a silk-screening process. A layer of photoresist material is applied to the surface of the board, and a stencil is used to apply the solder mask material to the surface of the board. The board is then exposed to ultraviolet light, which hardens the solder mask material in the areas where it will be applied to the board.
Step 7: Surface Finishing
The final step in the process is surface finishing. This involves applying a layer of metal to the surface of the board to protect it from corrosion and oxidation.
There are several surface finishing options available for MCPCBs, including:
- HASL (Hot Air Solder Leveling): This involves dipping the board in a bath of molten solder and then using hot air to blow off the excess solder.
- ENIG (Electroless Nickel Immersion Gold): This involves applying a layer of nickel and then a layer of gold to the surface of the board.
- OSP (Organic Solderability Preservative): This involves applying a thin layer of organic material to the surface of the board to protect it from oxidation.
Step 8: V-cut
A cutting line is formed on the surface of the PCB to make it easier to depanelize.
V-cut, also called V-Scoring or V-grooving, is the final manufacturing stage of PCBs. It cuts a “v” groove on the top and bottom of a PCB while leaving a minimum amount of material so that an individual PCB can be easily separated from the production panel.
Step 9: Testing
The purpose of conducting electrical and other necessary tests is to ensure the circuit board’s quality.
JHYPCB conducts 100% electrical tests on circuit boards before shipping to the customer. We also provide Hipot tests to meet the requirement of customers. Our PCB test systems include the following:
- The flying probe testers are suitable for testing prototypes, small batches, and highly complex PCBs.
- Universal grid testers require a separate test fixture and are well-suited for testing mass-production PCBs.
The manufacturing process for metal core PCBs is similar to traditional PCBs but with a few additional steps to accommodate the metal core. By following these steps, manufacturers can produce high-quality MCPCBs well-suited for high-power and high-thermal-conductivity applications.
By understanding the process, you can ensure that your MCPCBs are manufactured to the highest standards and meet the needs of your specific applications. MCPCBs offer several advantages over traditional PCBs, including better heat dissipation, improved durability, and enhanced electrical performance. By following the manufacturing process outlined above, you can produce high-quality MCPCBs that meet your customers’ needs.
Design for manufacturability
In addition to the steps outlined above, there are several other factors to consider when manufacturing MCPCBs. These include the design of the board, the choice of materials, and the quality of the manufacturing equipment. By paying close attention to these factors, you can ensure that your MCPCBs meet the highest standards of quality and reliability.
One important consideration when designing MCPCBs is the choice of the base material. Aluminum is popular due to its excellent thermal conductivity and low cost, while copper offers superior electrical conductivity and durability. In some cases, a combination of aluminum and copper may be used to achieve the optimal thermal and electrical performance balance.
Another important consideration is the design of the board itself. MCPCBs are often used in high-power applications, such as LED lighting and power electronics, which require careful attention to the circuit’s layout. You can achieve optimal performance and reliability by designing the board, focusing on minimizing the traces’ length and maximizing heat dissipation.
When it comes to the manufacturing process itself, it’s important to use high-quality equipment and materials. This includes precision etching machines, electroplating baths, and silk-screening equipment. Investing in the best equipment and materials ensures that your MCPCBs are manufactured to the highest standards of quality and reliability.