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Metal Core PCB Design & Manufacturing Concepts

Metal Core PCB Design & Manufacturing Concepts

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Metal core PCB consists of a layer of thermal insulation, copper foil, and metal plate, and you can also call it MCPCB. The basic benefits of metal core PCB include:

  • High magnetic conductivity
  • Great heat dissipation
  • Excellent mechanical strength
  • Easy processing

The base layer of the MCPCB is copper and aluminum, and you can choose to have any of them. Aluminum PCB is cheaper than copper, and you would find them in LED lights, mobile phones, and audio-frequency equipment. However, copper is better than aluminum in terms of performance. MCPCB was developed to overcome the heat dissipation issues occurring in high-power LED lights.

Things To Consider While Designing The Metal Core PCBs

The construction of the MCPCB stack-up depends on certain guidelines that we will discuss here. Such boards consist of a specific base layer, such as aluminum, copper, or even steel. You will have to determine the layer arrangement after selecting your desired metal and dielectric laminates. The type of the layer will determine other aspects, such as components and routing.
MCPCB has different types, depending on the number of layers as single-layer, double-layer, or multiple-layer metal core circuit board.

What Is A Metal-Backed PCB?

This Printed Circuit Board has a metal layer on its back, whereas the opposite layer has electric components. You can’t route traces on the back, however, through-holes are possible for routing between different dielectric layers, bringing ground to the metal substrate.

Metal Core PCB Routing

In the case of a double-side PCB, you can place through holes for routing between the metal core’s sides. You can use the multilayer dielectric stacks on the metal core’s sides to support different layers’ routing.You should ground the metal substrate for shielding, and to prevent it from acting as a monopoly antenna.

MCPCB Applications

Metal core circuit boards are ideal for aerospace and military industries that involve mechanical shocks, as well as high moisture and temperatures. So, MCPCB helps meet such requirements because they have a strong structure and a high thermal conductivity compared to PCB having an FR4. Such highly conductive circuit boards ensure an equal distribution of temperature when there is thermal cycling. So, it does not let the hot spots make closed components.
Metal core PCBs are also suitable for electric products which should work at high temperatures, such as high-current regulators, automotive electronics, and high-power LED lighting. The design of such applications depends on a precise stack up, and the board architecture should perform high at a low temperature.

Metal Core Printed Circuit board Fabrication Process

As there is a metal substrate in the stack up, such PCB involves a specific manufacturing process.You can use the FR4 dielectric in the case of a single-layer board by pressing the layer and bonding it to the metal plate.
If it’s a stack-up with a multilayer dielectric, you should first drill the metal core to have a layer transition independent of a short circuit. In the beginning, large holes are made and plugged with the insulating gels.Then, the gel has to be cured to make copper plating like a standard PCB. After that, you have to press and bond the remaining stack-up with the metal substrate. The stack-up needs through-holes followed by copper plating and residue cleaning.
The single-layer metal core circuit board has a metal base, copper layer, non-conducting or dielectric layer, solder mask, and IC components. Most thermoelectric separation applications consist of a COB or Chip-On-Board metal core circuit board,
It has two layers of copper conductor and both are on the metal core’s same side. Whereas the 2L MCPCB also has the metal core between two conductors, and designers call it a double-sided metal core circuit board.

Metal Core PCB Design & Manufacturing Concepts
Metal Core PCB Design

How to Select the MCPCB Components

It is essential to decide what components to choose when designing printed circuit boards as it can affect the final product. Such electronic components have different shapes and sizes, different power consumption specs, weights, and several other elements.
If you know how to choose PCB components efficiently, it can prevent big mistakes during design. We will help you in selecting the right components for your metal core PCB design.

You have to use certain design software tools to source the MCPCB components. These tools are necessary for all types of circuit boards, including a board with FR4, a rigid-flex circuit board, or a metal core board.
The surface mount technology is suitable for placing the components because it involves a minimum shorting to the metal substrate.You can also use the through-hole components,but you have to be careful to ensure that the solder mask does not get damaged on the back of the metal-backed PCB.
PCB fabrication involves multiple steps and the right design can enhance this process, preventing unnecessary design revisions.The manufacturer should have all documents having the fabrication details of the MCPCB.
Other than using metal cores, some passive techniques also help keep a circuit board cool through thermal management.

Designing MCPCB In A Closed Environment

The design of a multilayer PCB can become complex without compatible design software. You require the layout design tools for precise placement of the components, vias, routetraces, electrical, and thermal load crosscheck, etc.
You must have a good library of materials while designing the MCPCB. Likewise, the PCB layer-stack manager is required to handle your board’s structure. A suitable stack-up manager helps you to design a stack-up with an appropriate placement of the metal core, be it symmetric or asymmetric. Once the dielectric layers are defined, you need some groundwork for route traces and components’ placement.

Choosing The Design Software For PCB Layout

Different software help develop the PC Board layouts but make sure to choose the suitable one such as Altium. It helps you to have very precise CAD features to place the components. It also makes routing simple through special routing tools, whereas the layout engine helps ensure that the MCPCB is according to the design guidelines.
Remember that suitable software includes the 3-D design features to help you to design the complex mechanical parts of the MCPCB. You can also share your design with others through Altium 365, a cloud platform

Parameters of a Multi-Layer MCPCB

The design parameters of aluminum PCB sare described below.

  • Desired Aluminum thickness is 0.8-2.0mm
  • Solder resistance should be 288℃, >180 sec.
  • Breakdown voltage should be >3000v
  • The dielectric loss angle should be 0.03
  • Flammability should be UL 94V-0
  • Thermal conductivity should be 1.5W and 2.0W
  • Peeling strength should be >9lb/in

The minimum drilling diameter should be 1 mm in the case of an aluminum core, and the final diameter can be up to 0.3mm. There should be at least 1.2 mm spacing between the drill holes to avoid any damage.
Metal core PCB is also useful in several other areas having high mechanical loads where the dimensional stability should be high. Moreover, you can use it for electric vehicles, backlight units, automotive, audio systems, traffic lights, commercial buildings’ lighting, and solar panels.

Important Note

The digital devices depend on printed circuit boards for signals transmission to help them operate. These devices need a well-designed structure and manufacturing, but you have to encounter many issues in this case that we will discuss here. Circuit boards have different types and any issue in the design of a PCB would cause delays in its manufacturing, so you must know how to avoid them.

FAQs

What is A Metal Core Printed Circuit Board?
Metal core PCB has a metal base, such as aluminum, copper, or steel of which aluminum and copper are common.
Which One Is Cheaper, MCPCB with Aluminum or Copper?
MCPCB with aluminum is cheaper than copper. But, copper is better in terms of performance.
How Many Types of Metal Core Circuit Boards are there?
MCPCB has different types, depending on the number of layers, such as a single-layer, double-layer, or multiple-layer metal core circuit board.
Where Can I Use The Metal Core Circuit Board?
Metal core PCB is also useful for electric vehicles, backlight units, automotive, audio systems, traffic lights, commercial buildings’ lighting, and solar panels.

Wrap Up

There are several benefits of metal core PCBs, such as high magnetic conductivity great heat dissipation, excellent mechanical strength, and easy processing. The base surface of the MCPCB is copper and aluminum, and you can choose to have any of them. Aluminum PCB is cheaper than copper, and you would find them in LED lights, mobile phones, and audio-frequency equipment. But, copper is better than aluminum in terms of performance. Metal Core PCB was developed to overcome the heat dissipation issues occurring in high-power LED lights.
The design of a multilayer PCB can become complex without compatible design software. You require the layout design tools for precise placement of the components, vias, route traces, electrical, and thermal load crosscheck, etc.
Would like to know more about Metal Core PCB or pcb assembly services? Email us at sales@pnconline.com

High-Frequency PC Board

High-Frequency PC Board Applications, Specifications, and Challenges

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Some electronic products need special signals for which you have to make a high-frequency PC Board. Such a circuit board can provide 500 MHz to 2 GHz frequency that is ideal for microwaves, a radio frequency, and certain mobile applications that involve high-speed designs.

Several electronic components and switches are complex and need to transfer signals at a fast speed which is provided by high-frequency PCBs. Such boards need special materials because ordinary materials can affect signal transmission due to a poor Er value. Designers have to consider certain factors while designing the high-frequency Printed Circuit Board that we will discuss below.

Understanding a High-Frequency PCB

PCB involves connections of different components through conductive paths to run a specific electronic item. Designers use copper to develop a conductive path in a PCB. Circuit boards also help in signal transmission in the case of Wi-Fi and other satellite systems. In other words, you need a high-frequency circuit board to connect multiple objects through signals.

High-Frequency PC Board
High-Frequency PC Board Applications, Specifications, and Challenges

Which Factors Affect The High-Frequency PCB?

The design of a high-frequency PCB is not that easy because certain factors influence it and you have to consider them. Such boards have complex fabrication due to high-frequency laminates. Besides, the circuit board has to manage different applications’ thermal heat transfer.
You can’t use any material for high-frequency PCBs because it influences signal transmission that can be fast or slow, depending on the material. Moreover, the change in a material’s Er value also affects a PCB’s impedance.
Similarly, the dielectric material also plays a role in the design of high-frequency boards. Manufacturers use different dielectric materials as mentioned below:
1. Roger’s
2. Teflon
3. FR4.
The Roger’s is not expensive, and its DF and DK values are also less than other materials. Besides, it is ideal for prototyping manufacturing and applications. Moreover, there is a minimum chance of signal loss due to this material.
Whereas Teflon is used due to its high frequency that is up to 5 GHz that enhances the speed of signals between different parts and objects.
On the other hand, the FR4 is ideal for RF applications that need a frequency from 1GHz to 10 GHz. But, the electric products having FR4 have certain drawbacks due to their limitations.
The best material for high-frequency PCBs is Teflon due to factors like water absorption, DK, and DF. Teflon is more expensive than other materials, but it is ideal for products that need more than 10 GHz frequency of signals.
What Are The Standard Specifications Of a High-Frequency PCB?
You have to consider certain materials to have a high-frequency board as mentioned above. Moreover, the change in a material’s Er value also affects a PCB’s impedance. PCBs are available in different frequencies and have certain specifications that we will discuss below.
PCB Size: It should be at least 6 mm x 6 mm, and can go up to 457 mm x 610 mm.
PCB Thickness: It ranges from 4 mm to 5 mm.
Type of Material. Generally, it should be RO4003C, Ro3003, RT5880, and Ro3010
Weight of Copper: It ranges from 0.5 oz. to 2 oz.
PP: It includes Domestic-25FR, Domestic-6700, and Roger’s 4450F.
Min Spacing: It should be at least 3 mils.
Solder Mask Colors: Some common colors, in this case, are yellow, red, white, green, and blue.
Sides of Solder Mask. They are according to the design files.
Silkscreen Colors and Size: The colors are mostly white, black, and yellow, whereas the sides are according to the files.
Impedance Clearance: It is either plus 10% or minus 10%, depending on the design.
High-Frequency PCB Finish: It can be immersion tin, gold, silver, or electroless nickel. All these finishes should be RoHS certified.
Annular Ring: It should be min 4 mil.
Diameter of Drilling Hole: It is a minimum of 6 mils.

All the above species are standard and may change according to the board design. Besides, most circuit boards are customized and designed according to your needs. It is hard to recognize the best high-frequency circuit board, however, the material and specifications can help you in this case. You can also get professional help from a qualified PCB designer and/or a circuit board manufacturer.

Top Tips To Develop The Best High-Frequency PCB

As you know high-frequency PCBs have a high density and integration than other PCBs, they need a thoughtful design and fabrication. Such boards are more scientific than traditional circuit boards, and we have some tips to help you create a reliable PCB.

1. The pins that exist between various layers of a high-frequency PCB should have minimal leads as an alternate. Besides, the lead between different pins should be small.
2. When it comes to high-frequency devices, there should not be more bends between their pins.
3. Make sure that loops don’t develop while wiring.
4. The impedance of signals should be compatible.
5. The power pins of an integrated PCB should have a high-speed decoupling.

Meeting the Challenges of A High-Frequency PCB

No matter how well-designed is your high-frequency circuit board, you have to face some challenges during its fabrication and assembly. Let’s discuss some common issues in this case.

Consider Scaling

A professional fabricator knows that the thickness of internal layers decreases during the lamination of a multi-layered PCB made if FR4. So, the manufacturer should evaluate the percentage of such a loss. This helps printed circuit boards manufacturers get the right dimensions after the lamination process is over.
Besides, the laminate material is not hard like FR4, so it reacts differently. You should know the behavior of each material. Besides, you should scale each thickness separately or it will affect the registration from drill to pad and layer to layer. The fabricator should know all the statistics in this regard.

Preparing Different Layers

A board with several layers is complex, as you have to prepare each layer to have a strong bond, especially in the case of Teflon. Soft material can get deformed during the aggressive preparation of a surface. Such a deformation results in wrong registration, turning a PCB into a scrap.
Replacing the Teflon becomes expensive and causes delays in fabrication. So, you must prepare the surfaces carefully to avoid such challenges.

Preparation of Holes

You need to prepare the hole before plating. Like, it should be free from debris or epoxy attached to its walls. A smooth surface helps have a well intact copper plating. However, ceramic or Teflon involves a different kind of hole preparation.
This process involves a lot of care like you should consider various parameters of the drill machine to avoid the smearing of the substrate. After drilling, the hole is treated through plasma that involves gases. Poor preparation of the hole before copper plating might result in poor signal transmission. Hence, a PCB should have clean holes to perform better.

Considering the CTE Rate

The designer also has to consider the CTE or coefficient of thermal expansion of different materials. Different materials have different expansion rates, besides this expansion can occur in any direction like x, y, or z, depending on the heat. You can have well-finished holes if the CTE is less.
The factor of CTE can cause issues during a hybrid PCB of several layers when you join the high-frequency materials with FR4. So, the CTE of the materials should be compatible, or different layers or materials will expand differently, creating an issue.
Other than layers, vias also have to face this issue. Hence, the plugging material of the vias should be compatible with other materials.

Compatibility

Some FR laminates are similar to the RF materials in terms of behavior, and you should understand it. For example, the ceramic impregnated boards are hard when you drill through the drill bits. The hit counts should be less, besides, the RPM and spindle settings should be customized.
Sometimes the holes have fingers, which are hard to remove, so the adjustment of drilling parameters is essential to reduce fiber.
So, you can meet all the above challenges if you design and fabricate a PCB carefully by approaching a prototype pcb manufacturer to verify your design.

Importance of a High-Frequency PCB

A high-frequency PCB is widely used in different industries, such as military, interchanges, gadgets, vehicles, PC, instrumentation, clinical, and other such fields. These circuit boards are more in demand than before, and 15% of circuit boards in the market come up with high frequency.

Final Words

Sometimes the electronic components and switches are complex and need to transfer signals at a fast speed which is provided by high-frequency PCBs. Such boards need special materials because ordinary materials can affect signal transmission due to a poor Er value.
You can’t use any material for high-frequency PCBs because it influences signal transmission that can be fast or slow, depending on the material. Moreover, the change in a material’s Er value also affects a PCB’s impedance. PCBs are available in different frequencies and have certain specifications.
Would like to know more about high-frequency PCB applications or pcb assembly services? Email us at: sales@pnconline.com