Multilayer metal core PCBs are commonly used in various electronic applications, including communication electronics, power converters, LED boards, LED Based Products, and medical devices. In designing and manufacturing these boards, it is important to pay attention to thermal management and transfer. In addition, one should carefully control the thickness of the boards.
Multilayer metal core PCB is a type of PCB made of metal layers. You press the metal cores during manufacturing and remove the residual filler compounds. You then plate the inner layer cores before preparing the board for lamination. The rest of the process follows the standard manufacturing process.
Introduction to Multilayer metal core PCB
Multilayer metal core PCB, or MCPCB, is a printed circuit board with a metal core. It has several layers. This circuit board contains a thermal insulating layer made from a metal plate or copper foil. This type of PCB has unique characteristics including good thermal conductivity and heat dissipation. Different types of metal core PCB are available, including copper and aluminum. Copper is the preferred metal for performance but is significantly more expensive. The thickness of this material is usually between 1mm and 4mm.
Metal core PCBs are double-sided, so routing can pass between both sides. In addition, we can use multilayer dielectric stacks on both sides. Despite this, it is important to ensure that you ground the metal layer. This will prevent the metal layer from acting as a big antenna. In addition, some applications may require mourning the metal core to the enclosure.
The outer layers consist of conductive materials and a dielectric layer connects them. This allows for higher flexibility and impedance control. Additionally, these PCBs have reduced EMI shielding and ground layers.
Multilayer metal core PCB differs from conventional FR4 PCBs because it contains a metal layer between two conductive layers. Typically, it consists of two copper conductor layers. Therefore, this PCB requires an additional pressing step to bond the layers together.
Advantages of Multilayer metal core PCB
Multilayer metal core PCBs (MCPCBs) have several advantages over standard FR4 PCBs. They do not require vias for thermal relief and the entire bottom side of the board is made up of metal, making it more efficient thermally. In addition, MCPCBs require little or no drilling and only a few large holes for mounting.
These PCBs have higher thermal conductivity and can handle higher power levels and density. They are typically made from aluminum, which is inexpensive and recyclable. They also transfer heat eight to nine times faster than traditional FR-4 PCBs. Because of the aluminum’s thermal conductivity, the dielectric layer must be very thin, usually between 0.003 and 0.006 inches thick.
MCPCBs are ideal for applications that produce heat, such as LED lighting systems and power circuits. In addition, they can improve circuit reliability and make components last longer.
This type of board is ideal for circuits with high switching power. It also offers better thermal management than epoxy PCBs. Its thin dielectric layer allows efficient heat transfer, making the metal core less susceptible to cracks. Moreover, metal core PCBs can achieve higher circuit densities than other materials.
A multilayer metal core PCB can be double-sided, allowing routing between both sides. It can also support routing on multiple layers. Ideally, the metal layer should be grounded. This will help prevent the board from acting as a monopole antenna. Depending on the application, mourning the metal core to a protective enclosure may be necessary.
You can also male multilayer PCBs with a single-sided conductive component placement. JLCPCB is equipped with a large library of SMT parts and manufactures them in-house. It also performs automated solder paste placement. In addition, its metal core makes it suitable for applications that require high levels of durability and reliability.
Structure & Base Materials for metal core PCB
We can make multilayer PCBs using three types of base materials. These include aluminum, copper, and stainless steel. Aluminum is the most common metal in use for the base material, while copper is more expensive but has superior thermal conductivity. Both copper and stainless steel have advantages and disadvantages, and you should choose based on your needs. The base material plays an important role in insulating the components. The base material is usually one to four mm thick, depending on customer specifications. Regardless of the material, the base layer is usually the first layer of the PCB.
The base material comes from a thin copper film, which will eventually contain the traces. The upper copper layer is typically between 1 and 4oz thick. The innermost layer is usually a dielectric material, which isolates the metal layer from the copper film and allows for rapid heat transfer. One can make the metal layer from aluminum and is 1.6 to 8mm thick.
Multilayer metal core PCBs are more thermally efficient than traditional PCBs and can handle high power and density circuits. Aluminum is the most common base material, and is inexpensive and recyclable. These boards transfer heat eight to nine times faster than FR-4. Because of their higher conductivity, metal core PCBs require a very thin dielectric layer. The dielectric layer thickness is typically between 0.003 and 0.006 inches.
Copper Invar Copper (CIC)
It is possible to make multilayer metal core PCBs from Copper Invar Copper (CIC) material. The CIC layer contains a nickel-iron alloy sandwiched between two copper layers. It is useful in high-temperature environments to control the expansion of circuits. Additionally, it is good for PCBs with ground planes, power supplies, and metal cores. CIC is in wide use within the aerospace industry.
CIC has a low coefficient of thermal expansion and high thermal conductivity. Therefore, it can be useful as a metal core in PCBs but requires a special etching process. The different etching characteristics of Invar and Cu lead to varying etching rates. In the case of Cu-Invar-copper (CIC), FeCl3 was more effective than CuCl2 in the process.
The metal core is the thickest part of the board. A metal backing plate backs it. Common thicknesses are 1mm, 1.5mm, and 3.2mm. This metal layer helps the circuit remain flat and provides a sufficient thickness for mounting hardware. On the other hand, the exposed metal plate side of the board is not coated with surface finish. This prevents noise from entering the circuit.
Iron-based multilayer PCBs are those with an iron-based metal core. These PCBs have several layers of conductive material on one side and insulating material on the other. Copper foil and iron are common choices for the conductive layer. Other materials used for the insulating layer include polyester, ceramics, and modified polystyrene ether. Multilayer PCBs require more technology and cost a bit more to produce.
Metal-based multilayer PCBs are generally more robust than their aluminum counterparts. They have lower thermal conductivity than their aluminum counterparts, but are also more expensive and heavier. As a result, they are usually useful in applications where the temperature is extremely high. Another advantage of iron-based PCBs is their ability to dissipate heat from critical components. These PCBs also offer conductive cooling, making them great for high-heat applications.
Metal-based multilayer PCBs are particularly suitable for applications where cooling multiple LEDs is essential. They also offer excellent reliability, and are not prone to bend in extreme temperatures. Their special layers also make them more conductive than FR-4 PCBs.