What You Need to Know About High Multilayer PCB
High Multilayer PCB is an advanced type of printed circuit board used in modern-day electronic devices such as smartphones, X-ray machines and medical equipment etc. These boards have a much higher layer count than their single- or double-sided counterparts and require specific domain expertise for their design process.
The layered structure of a multilayer PCB is separated by insulating material, with different planes used for signal, power and ground routing. Vias are built into the layers; buried vias are used to improve routing density and standard vias are also available.
Layer Stackup
When you need more functionality than is possible with a single-layer PCB, a multilayer stackup is the solution. In a typical layered structure, signal layers are separated from power and ground planes to reduce noise issues. In addition, buried layers between signal layers are used to prevent crosstalk and reduce impedance.
This arrangement also allows high speed signals to be routed on the inner signal layer rather than on the top and bottom of the board. This helps to optimize the signal-to-noise ratio of the circuit and improve EMC performance.
The number of layers in a multilayer PCB varies according to the complexity of the design and the component density required. For example, a High Multilayer PCB 14 layer stackup is often used when multiple BGA’s are required. This configuration requires more routing (signal) layers and extra shielding layers for critical nets.
Choosing the right layer stackup is essential for proper PCB design and fabrication. This involves careful consideration of the prepregs and core materials as well as the metallurgical properties of each layer. It also includes the calculation of trace widths for different controlled impedance traces, such as 50 ohms and 100 ohms differential.
It’s important to consider these factors before starting your PCB layout, as it can be difficult and time consuming to make changes once you’ve started. Millennium Circuits can help you select the right multilayer PCB for your application. Contact us today to discuss your requirements.
Vias
Vias in multilayer PCBs are the connections between layers. They are used in a wide range of applications from computers and telephony circuits to handheld devices and industrial systems. Vias help to make the different traces present on various layers of the PCB connect with one another, and they can be plated with either epoxy or metal. The type of via used on a PCB depends on its function and the design of the layout.
Through-hole vias, which are drilled through the outer layer of the board, are the most common and cheapest to fabricate. The PCB fabricator then etching the hole and fills it with either epoxy or metal, depending on its intended application. Typically, if a via is designed for thermal application to disperse heat across the PCB, it will be filled with metal epoxy instead of conventional epoxy.
To increase routing density, PCB designers can also choose to use landless vias, which have no pads but are connected to a specific plane on the board. They can be used in the signal and power or ground planes to improve signal integrity. The positioning of the vias in the PCB can also reduce EMI noise by limiting crosstalk between levels. However, the size of the vias can impact the overall performance and reliability of the PCB because they can create parasitic inductance or capacitance.
Copper Thickness
The copper thickness on a multilayer PCB varies depending on the current that passes through the board. For example, if the board will be handling a high current, the copper must be thicker so it can handle the higher levels of current without overheating. This is why it’s important to use a trace width calculator to determine the requirements of your specific project. The calculators will also factor in the prepreg thickness, solder mask thickness, etc.
Standard PCBs usually have a copper thickness of 1 ounce, but manufacturers can customize the thickness according to your requirements. Thicker copper will increase the price of the board because it requires more materials and is more difficult to process.
If you’re designing a PCB, try to spread the copper evenly as possible across the layers. This will make it easier for the manufacturer to etch the copper features, and it will also reduce the risk of mistakes. The optimal copper distribution will depend on the power levels and impedance of your design, but you can use a trace width calculator to get an idea of what the minimum copper requirements are for each layer. It’s also a good idea to add as much spacing as possible between copper features, since it’s harder to etch narrow gaps than wider ones. This will help prevent shorts between traces and improve signal integrity.
Material
The material used in High Multilayer PCBs is crucial to the circuit board’s performance. It affects the speed of signals that travel through the circuit and the ability to perform in harsh environments. It is important to use materials with high thermal resistance and impedance matching. This ensures that the signal is transmitted correctly and does not get corrupted. It is also necessary to consider the operating temperature and the environment in which the device will be used.
The construction process for a Multilayer PCB involves laying sheets of inner core, prepregs and copper foil in a hydraulic press. Then, resins from the High Multilayer PCB Supplier prepregs and copper foil join the layers together with pressure, heat and vacuum. It is important to keep the resins from drying out, or the layers could separate. In addition, the press must be set up to meet the interlayer alignment requirements of a multilayer PCB.
Most modern consumer electronic devices contain multilayer PCBs. They are favored over single-layer devices because of their small form factor, durability and multifunctionality. They are commonly used in computers, telecommunication circuits and handheld devices. They are also used in the medical industry for their precision and durability. X-ray equipment, heart monitors and CAT scan equipment all use Multilayer PCBs. In the automotive industry, multilayer PCBs are also used because they can withstand vibration and pressure.