What does Multilayer PCB Mean?

What does Multilayer PCB Mean?

Multilayer PCB can be referred to as a multi layer circuit board that is composed of three or more layers. This is made up of a substrate layer, which features a conductive metal on its two sides. It also offers enhanced functionality. They are utilized in complex devices that require a very high number of connections.

Multilayer printed circuit boards must feature at least three layers of conductive layers, which are located at the center of the material. This multilayer PCB manufacturing entails the fusing of fiber-glass alternating epoxy-infused conductive core materials and layers.

Both of them are laminated using high hydraulic press pressure and temperature. This process leads to the prepreg melting, which later results to the joining of these layers.

Steps Used in the Manufacturing of Multilayer PCB

The manufacturing process of multilayer circuits involves some steps. Let us consider them.

Developing the Desired Design

Plan the layout PCB design following all the requirements and encode it. By doing this, you are making sure that the different aspects and parts of the designs are error-free. A completed PCB design is then ready for fabrication building.

Printing of the PCB Design

As soon as the check completion has been finalized on the design, then it can be printed. You punch the registration hole to serve as a guide for aligning the films as you continue with the process.

Print the Copper Utilized for the Interior Layer

This step is the first while making the inner layer of the PCB. You print the multilayer PCB design; then copper is re-bonded to the lamine piece that serves as the PCB structure.

Discard unwanted copper

Copper that photoresist does not cover is removed with a strong and effective chemical. As soon as it is removed, it leaves just the needed copper for your PCB.

Lamination of the PCB Layers

Once the layers are free from defects, then you can fuse them. You can achieve this process in two spes, which include the lay-up and the laminating step.

Drilling

Before you drill, the drill spot is located with an x-ray machine. This helps in securing the PCB stack.

PCB Plating

This process helps in fusing the different PCB layers making use of a chemical.

Imaging and Plating of the Outer Layer

By doing this you are guarding the copper found on the outer layer by applying the photoresist.

Final Etching

To protect the copper during the process, a tin guard is utilized. This gets rid of unwanted copper. This also ensures properly established PCB connections.

Applying Solder Mask

After cleaning the PCB panels, you apply an ink epoxy with a solder mask.

Completing Silk-screening and PCBs

PCB plating is done to make sure that the soldering of the components can be achieved. The process of screening points all the important information on the PCB.

Electrical and Testing Reliability

To ensure functionality, the technician carries out tests on several areas of the PCB.

Profiling and Cutting

According to the requirements of the customer, different PCBs are cut from the initial panel. Then the inspection of the board is done, and the errors rectified before it is sent for delivery.

Materials Used in the Manufacturing of Multilayer PCB

The different materials utilized in manufacturing multilayer PCBs are boards, copper foil, resin system, substrate, vias, infused fiberglass sheet. Using an alternating sandwich, you can laminate these materials together.

All the planes of copper are etched and the plating through of all internal vias is done before the layers.

Multilayer PCB: Benefits

Multilayer PCBs come with lots of great benefits. Some of them include:

Higher assembly density

Provision of high speed and high capacity, as a result of their electrical properties

Weight reduction of devices

Elimination of connectors needed for multiple separate PCBs, thereby simplifying its construction.

Multilayer PCB: Uses

Multilayer PCBs can be utilizes in many areas. Let’s consider some of them.

They are used in manufacturing CAT scan, heart monitors, and modern x-ray equipment.

Utilized in the production of high-speed circuits due to their functionality and durability

Used for headlight switches and onboard computers due to their high functionality and heat resistant ability

The running of machinery and industrial control system utilize them due to their small size and durability.

Consumer electronics such as microwaves and smartphones also make use of multilayer PCBs as a result of their small size and functionality.

Satellite applications, GPS, and signal information, also make use of multilayer PCBs

Used in the production of computer electronics that are utilized in motherboard servers due to its performance and space-saving attributes.

Identifying a Multilayer PCB

You can identify a multilayer PCB through the following

How your electronic equipment operates briskly, as well as the ultimate board’s operational setting

The configuration, layer count, and the value of the board’s building also play a role in the identification

The board routing density

The operating capacity, speed, parameters, and functionality, distinguishes if the PCB is a multilayer one

They make use of simple production techniques, but still focusing on performance and quality.

Multilayer PCBs are usually difficult to style, in contrast to single-layer ones that have an easy production process

Single-layer PCBs are usually produced in large quantities and can also be ordered in bulk. This helps in reducing the price per board thereby ensuring that producing these devices are less expensive. For multilayer PCBs, producing them are usually tedious, and it may be difficult producing them in large qualities at once.

Multilayer PCB circuit boards have at least three conductive layers, two of which are on the outer surface, and the remaining layer is integrated into the insulating board. The electrical connection between them is usually achieved through plated through holes on the cross-section of the circuit board. Unless specified, multilayer printed circuit boards are the same as double-sided boards, generally plated through-hole boards

Multilayer printed circuit is the product of electronic technology development in high speed, multi-function, large capacity, and small volume. With the continuous development of electronic technology, especially the extensive and in-depth application of large-scale and very large-scale integrated circuits, multilayer printed circuits are rapidly developing in the following directions: high density, high precision, and high layers, tiny lines and small holes, blind and buried holes, high plate thickness to aperture ratio and other technologies to meet market needs.

Why are PCB multilayer boards all even-numbered layers?

It can be manufactured in a PCB factory. The four-layer board generally uses a core with one copper foil on each sideand a three-layer board with one copper foil on one side. They must be pressed together.

The process cost difference between the two is that the four-layer board has one more copper foil and bonding layer. The cost difference is not significant. When the PCB factory makes a quote, they are generally quoted on an even number basis. Also, 3-4 layers are commonly quoted as a grade. (For example:If you design a 5-layer board, the other party will quote at the price of a 6-layer board. That is to say, the price you design for 3 layers is the same as the price you design for 4 layers.)

In the PCB process technology, the four-layer PCB board is better controlled than the three-layer board, mainly in terms of symmetry. The warpage of the four-layer board can be controlled below 0.7% (IPC600 standard), but the size of the three-layer board is large. At that time, the warpage will exceed this standard, which will affect the reliability of the SMT assembly and the entire product. Therefore, the designer shouldnot design the odd-numbered layer board. Even if the odd-numbered layer is necessary, it will be designed as a fake even-numbered layer. That is to design 5 layers into 6 layersand 7 layers into 8 layers.

Multilayer PCB is manufactured by stacking two or more circuits on top of each other, and they have reliable pre-set interconnections. Since drilling and plating have been completed before all layers are pressed together, this technique violates the traditional manufacturing process from the beginning. The two innermost layers are composed of traditional double panels, while the outer layers are different. They are composed of single independent panels. Before pressing, the inner substrate will be drilled, through-hole plated, pattern transferred, developed, and etched. The outer layer to be drilled is the signal layer, which is plated through so that a balanced copper ring is formed on the inner edge of the through-hole. The layers are then rolled together to form a multilayer PCB, which can be connected to each other (between components) using wave soldering.

Pressing may be done in a hydraulic press or an overpressure chamber (autoclave). In the hydraulic press, the prepared material (for pressure stacking) is placed under the cold or preheated pressure (high glass transition temperature material is placed at a temperature of 170-180°C). The glass transition temperature is the temperature at which an amorphous polymer (resin) or part of the amorphous region of a crystalline polymer changes from a hard and brittle state to a viscous, rubbery state.