Contents
Multilayer PCB
1.1 Multilayer PCBs—What is a Multilayer PCB?
Multilayer printed circuit boards always have over two conductive material layers. In double-sided PCBs, you will only get two conductive material layers and not more than that.
However, multilayer PCB’s conductive material layers start from three at the center of the insulating material.
Multilayer PCBs provide more wiring area. They are made by combining several double-sided boards with an insulating material.
Usually, you can design a multilayer PCB as a rigid board, as it is complicated to create a flexible PCB.
We recommend designing between four and eight layers of conductive material. These are usually enough to fulfill any ordinary circuit’s needs.
You will realize that adding more layers without vital needs will only increase your expenses. Figure 1 shows a multilayer PCB.
1.2 Why do you need them?
Nowadays, using multilayer PCBs is the latest industry trend. Electronics are moving towards a reduction in size along with multi-functional products. You will fall behind your colleagues or competitors if you do not evolve with what the market demands.
Double-sided and single-sided PCBs have limited ability to balance functionality and size.
However, you can get that with multilayer PCBs.
In the next sections, you will learn that multilayer PCBs also have many disadvantages, such as high cost. But cunning people know that cost should not be a problem if you are getting high-quality products.
Moreover, the electronic components are getting smaller day by day, so they are demanding small PCBs.
If you keep using traditional boards, you can imagine where you stand in this evolving technological world.
In this section, we introduced multilayer PCBs and their needs. The next section will explain their construction and design rules. Stay tuned.
Designing the Multilayer PCB
2.1 Multilayer PCBs—How are they made?
Before constructing a multilayer PCB, you must know about Vias and their work.
Let us briefly introduce these terms here. Vias exist in three main types: buried, blind, and through vias.
Buried vias are concealed within PCB layers, and you can never see them outside. They onnect internal layers that, through vias, cannot reach.
On the contrary, blind vias do not travel through the whole circuit board.
They only make connections between outside and internal layers.
Knowing how to use these three types of vias is the key to effectively designing a multilayer PCB. They will make PCB routing amazingly simpler.
However, if you are worried about cost, you should use buried and blind vias when it is an ultimate necessity.
Multilayer PCBs with vias will allow electronic components to be placed in the desired small space. Trace distance will also be reduced, enhancing signal integrity.
The laser is mostly used to drill blind vias, which are mostly about 0.1 mm. What does that mean? You can place them on the pads of the multilayer PCB.
Nonetheless, you should avoid placing vias on BGA pads.
2.2 Things to do before professionally designing the Multilayer PCB
Before creating the PCB layout of the multilayer PCB, you should investigate the following steps:
1. You should finish your circuit design and check its functionality.
2. You should complete your Part list, Netlist, and BOM.
3. You should know the size of the PCB that your project needs.
4. You should do homework on how many layers you need, then size, how you should stack them up, or what kind of vias they should incorporate. For instance, Eagle software uses the following notation:
5. p + q means these layers and prepreg are stacked together.
6. P * q means these layers are stacked with a core.
7. () sho s through and buried vias.
8.[a:… : b] illustrated blind vias.
9. You should ensure you can comprehend the basic specifications of electronic components. For example, several components may have different standoff/EMI distance values from other parts.
10. It would be best if you also decided upon the trace widths, ring sizes, vias sizes, clearances, and scoring. You should declare how much space the circuit board requires, as these occupy a lot of space.
So, these are a few things that would lead you towards successfully designing a PCB multilayer.
In the next section, we will answer the primary two complications related to this field.
3.1 What will happen if you keep on adding more layers?
If you keep adding more layers, cost complications will arise. However, t value and layer addition do not follow a linear relationship.
Because drilling, plating, solder masking, and silk screening only need to be done once, they are not dependent upon several layers.
But, etching, photo-exposing, and lamination need to be performed once after every two layers.
You will increase your expenses roughly in the following manner: if you go from two layers to four or six layers, you increase your cost by 1.5 to 2 times, respectively.
However, you will also get many benefits to balance the increased costs:
1. You will get a simplified routing procedure.
2. Board size will be reduced because of the higher density of the layout.
3. You will use ground planes or multiple ground planes.
4. You will have the additional heat-sinking capability.
5.You will use plane layers to separate and shield analog and digital or sensitive analog circuits. Figure 3 d demonstrates the multilayer PCB being soldered by robotic soldering.
6. solid pla Ayers will be for a controlled and constant impedance line.
3.2 Multilayer PCBs—How to identify Multilayer PCBs?
If you feel cynical and want to know the total number of layers laminated in the multilayer PCB in your hand, we can help you with that. Simple, fo l w the following steps:
- Shine a light on the board edge to see the copper planes. You will be able to see signal traces more thoroughly.
2. Use bright light to examine the inner layers of the multilayer PCB.
3. The best area to look for inner layers is where you cannot see paths or lines on the outer layer.
4. You can al o look around the edge to read the number of layers. Some manufacturers print the total number of layers on the board.
In this section, we discussed the consequences of adding a higher number of layers and identifying their number by looking at the board.
In the next section, we will highlight the advantages of the multilayer PCB.
Advantages of Multilayer PCB
Multilayer PCBs offer many advantages when compared with single or double-sided layer PCBs. Some of them are:
1. Layering provides higher assembly density, which in turn enhances capacity, functionality, and speed.
2.You are getting a smaller PCB. Adding a greater number of layers increases the surface area, not the size, of multilayer PCBs.
3. Multilayer P Bs are also lighter in weight, which requires a smaller number of wires, connectors, and related components.
4. You will get enhanced design functionality. That is be a se of better EMI shielding, controlled impedance attributes, and design quality.
Furthermore, you are getting a simple routine procedure.
Figure 4 shows an example of how the final form of a PCB routing procedure may look like.
So, what do these benefits mean for you?
Should you choose a multilayer PCB? Let us help you decide. Fundamental, if you want lightweight, small, and high-quality, you should choose a multilayer PCB.
Also, a multilayer PCB will be your savior if your design is complicated.
However, other PCBs can be cheaper if you are not worried about weight and size.
In this section, we discussed the advantages of the multilayer PCB and listed its limitations.
Limitations of Multilayer PCB
Well, there are a few limitations when dealing with multilayer PCBs. It is advisable to consider them before finalizing whether to go for them.
- Multilayer P Bs are expensive. If you are a budget person, consider the total project cost before selecting a multilayer PCB.
2. More Manuf c uring Time. This is a limitation if you are time-conscious or have less time to complete the project.
3. Complex Re a r. Multilayer P Bs require a more complicated mending procedure than other types of PCBs.
These are the only main limitations that should bother you before making a choice. Tell us in the comments below if they matter to you.
Figure 5 demonstrates that a smartphone can be used to analyze the printed circuit boards.
Is it not that amazing?
In this section, we discussed the limitations of the multilayer PCB. In the next section, we will tell you about its major applications.
Multilayer PCBs–Applications of Multilayer PCB
In Aerospace, multilayer PCBs are particularly valuable because of their space and weight advantages. Figure 6 s o s a close view of a helicopter’s rotor.
You will also see multilayer PCBs in applications where the level of “cross-talks” is vital. Apart from t ese, the following areas are using multilayer PCBs:
- Data storage
- Signal transmission
- Computers
- File servers
- GPS technology
- Industrial controls
- Test equipment
- X-ray equipment
- Cell phone transmission
- Central fire alarm systems
- Cat scan technology
- Cell phone repeaters
- Handheld devices
- Atomic accelerators
- Nuclear detection systems
- Space probe equipment
- Fiber optic receptors
- Weather analysis
- Heart monitors
- Satellite systems
Conclusion
In conclusion, electronic designs are becoming more complicated every day. Designers are looking for more wiring areas and need small PCBs.
Furthermore, they also need higher assembly density and want to incorporate their design functionality fully.
Single- and double-sided PCBs do not fulfill your needs. So, in this case, multilayer PCBs are your solution.
We have added all the necessary information related to multilayer PCBs. This artic e will help you decide whether to use them over other types.
We at WellPCB can manufacture high-quality multilayer PCBs.
To order, go to our website.
While placing the order, you will need to fill in some specifications for your PCB. After that, our Engineers will check your order, and then an instant quote will also appear.
And then, in no time, your multilayer PCB will be at your doorstep as we also offer quick deliveries.
Still, do you need more information?
You can contact us right away! Do not hesitate even for a second.
