The development of microelectronics is like an unstoppable torrent, and complex multilayer printed circuit boards have also become a hot component. Differentiating from the standard two-layer PCB, a multilayer PCB is made up of more layers that are laminated together and insulated by a greater series of prepreg and copper that are stacked on top of each other. Generally, we call a circuit board with more than 4 circuit layers a multilayer PCB (MLB PCB), which means that designers can design more circuits inside the PCB. With a multi-layer PCB, there is a repeated pattern of prepreg and core (substrate) material in between the outermost top & bottom layers, offering several advantages to both through-hole and surface mount designs. Usually, a 4-layer circuit structure can give the PCB good electrical performance and is suitable for most electronic products, but we are still happy to increase its number of layers to obtain higher pressure-bearing capacity.
Get a Multilayer PCB Quote from FS Technology
FS Technology is a one-stop PCBA manufacturer, providing PCB manufacturing and PCB assembly services that meet the needs of a large number of engineers. Partnering with FS Technology will get you great value and a fun trip. We produce multi-layer circuit boards from 1-58L for our customers in a simpler step: structuring, lamination, and through-hole plating. Most of the time, various unexpected things will happen with the increase in the number of board layers, but we can avoid the risks that customers need to face through strict quality control and commitment. The following is the multi-layer PCB sample produced by FS Technology:
High-quality Multilayer PCB Supplier
Quality is the foundation of FS Technology, and it is also the hard cornerstone of development. As a turnkey PCBA company that prioritizes quality, we control the quality of PCB from the source. If the quality of the raw material used in the project cannot be guaranteed, the produced circuit board may have various issues, such as blistering, delamination, cracking, board warpage, and uneven thickness. So, the quality of raw material is the premise to ensure the production of high-quality multilayer PCB, and strict incoming inspection is the first step of service. We maintain a zero-tolerance attitude towards product defect issues. Once a problem is found, it will immediately register a report and develop a solution.
In past manufacturing experience, it was found that the quality of different types of multilayer boards varies greatly. For example, ceramic multilayer PCB, metal core multilayer PCB, HDI multilayer PCB are much more difficult and risky to manufacture than ordinary multilayer boards. In order to ensure the quality of production and avoid errors in the subsequent assembly process, we need to ensure the quality of the product produced. Professionals can easily judge the quality of the printed circuit board after receiving the product, but this will undoubtedly slow down the progress of the entire project. FS Technology is here to show you our quality control standards through advanced manufacturing methods and strict testing.
Perfect Manufacturing Process
The manufacturing process of multilayer PCB is rough as follows:
- Create Inner Image
- Inner Layer Etching
- Multilayer PCB Stackup
- Through Holes and Mounting Holes
- Outer Layer Etching
- Plated Through Hole
- Add Solder Mask
- Draw the Silkscreen Layer
To start with, the base of a standard two-layer PCB is the substrate material (core), which is oftentimes fiberglass epoxy resin. The next layer is the copper which is laminated onto both sides of the substrate to establish electrical conductivity and finally, the solder mask is laminated onto both sides of the copper to protect the copper layer against oxidation and to help make soldering easier. If we take a 4-layer multilayer board for example, it is manufactured by essentially combining two standard two-layer PCB boards together, oftentimes with lamination under high heat and pressure (compression) with a hydraulic press. Of course, there will be multiple layers of prepreg, copper, and core material that will be stacked on top of each other in between the two outermost layers (making up the multiple layers), which will all then be compressed together to make a multilayer PCB.
FS Technology’s PCB manufacturing process is nowadays all done by high-tech machinery which, through the use of software, can be done effortlessly and with close to zero inaccuracies, making it suitable for mass production.
Multilayer PCB Testing
We provide a variety of PCB testing services, including but not limited to the following:
Testing circuit boards is an important part of the production process, whether it is a PCB or a PCBA, especially for a multi layer PCB with a more complex circuit structure. The number of layers of the circuit board is realized by stacking technology. When the number of these layers increases, the manufacturer will face greater manufacturing risks. For this reason, the testing process of multilayer PCB board should be paid attention to.
In the production workshop of FS Technology, each production process is equipped with a special quality inspection post to ensure that each process has the implementation of operating procedures, to facilitate the overall control of PCB quality. FS Technology promises that no matter how strict the testing process these boards have gone through during production, we will strictly implement the sampling standards provided by customers after the production is completed. If the qualified rate of product sampling inspection is up to standard, it will be approved to leave the factory, otherwise, comprehensive inspection and maintenance will be carried out.
Service Area
Printed circuit board are an essential hardware component of almost all electronic & electrical devices, as it allows for a complete (closed) circuit to be made between electronic components. Predominantly with the use of conductive copper tracks & traces on a PCB, an electrical connection can then be made from one point to another. Typically, you will find that many PCB are two-layer boards, meaning that there is an inner core layer (substrate) in the center of the board that is sandwiched between first a solder mask on the outermost layer (giving it its color) and a copper coating on the subsequent bottom layer, giving the traces its conductive properties. However, you have to use high-precision multilayer PCBs for complex applications.
In the past operations, FS Technology’s customers are located in more than 70 countries around the world, and their fields are also different. The same thing is that they rely on our strong manufacturing capabilities to gain advantages in their respective fields. Here are some of the industries we have served:
Top-notch Manufacturing Capabilities
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Necessity of Multilayer PCB
The number of layers of the circuit board is an important factor that leads to rising costs. For this reason, the necessity of considering multi-layer PCB needs to be considered before the project begins!
Electronic Development Status
The core of Moore’s Law states that the number of transistors that can be accommodated on an integrated circuit doubles every 18 months. As the packaging density of integrated circuits increases year by year, the demand for electronic products develops in the direction of multi-functionality and miniaturization, necessitating the use of multi-layer boards. In the layout of printed circuit boards, unforeseen design problems such as noise, stray capacitance, and crosstalk may arise. As a result, minimizing the length of signal lines and avoiding parallel routes has become a challenging task in circuit board design.
Unfortunately, whether it is a single or double-layer board, designers face limitations in achieving a satisfactory solution due to the restriction on the number of crossovers that can be achieved. The manufacturing of multilayer circuit boards has become imperative in an environment of extensive interconnection and crossover requirements. The original intention of multilayer PCB fabrication is to provide more freedom for the circuit layout of complex electronic products. Therefore, it is essential to consider whether your electronic project truly requires more layers of PCB, and this can be determined by examining its advantages and disadvantages.
Multilayer PCB Advantages
Small Size
The smaller size of MLB is attributed to two factors: reduced surface area and assembly techniques.
Increasing board surface area by adding layers: It is evident that large-sized PCBA boards cannot fit into electronic equipment easily. Just like an unfolded quilt being difficult to place inside a box, large boards are impractical. The principle of multilayer PCB board is to obtain more wiring within the same size by increasing the number of layers, akin to folding the quilt to fit it into the box.
Assembling ML-PCBA using SMT technology: High precision multilayer PCB is extensively used in cutting-edge applications, often in conjunction with SMT assembly. Traditional plug-in components struggle to meet the demands of micro/nano consumer devices and are replaced by SMD components. Consequently, assembly can be completed on smaller-sized PCB.
High Density
The most common application demonstrating the high-density benefits of multilayer circuit board is mobile phones. With the iterative update of the production process, the size of the mobile phone is getting smaller and smaller, but the function has not been affected but improved, thanks to the high-density interconnected (HID PCB) MLB used in its design. When we increase the number of layers of the PCB, although its size remains the same at this time, the multilayer HDI PCB increases the wiring density through layering, enabling it to accommodate more functions, speed, and capacity.
More Lightweight
A multilayer board can replace the need for multiple PCB, providing greater durability as it eliminates the requirement for external hardware and connectors. The removal of connectors also reduces the weight of electronics, making them suitable for small appliances. Additionally, this reduction in hardware and connectors may lead to lower maintenance and replacement needs in the long run.
In general, the most significant advantage of multilayer circuit boards is their small form factor, lightweight design, and increased capabilities for handling more complex electrical routing. In this era of electronics, simplicity is crucial, and eliminating unnecessary parts in a project can be favorable in terms of cost and troubleshooting. Large-scale industrial production faces challenges in producing and manufacturing numerous designs and enhancing production efficiency. Multilayer PCB can fill this gap and provide a compact yet reliable solution for improving aspects of PCBA construction and production.
Multilayer PCB Disadvantages
Design Difficulty
Even though multilayer circuit boards present themselves with many enticing advantages for an electronic hobbyist or even an avid designer, there are certainly a few complexities of the design that you should keep in mind when considering multilayer PCB.
Right from the start of the design process, there definitely is a learning curve involved in designing a multilayer PCB compared to an ordinary PCB that you may have made in the past, as it involves more complex routing & design features to keep in mind. The layers that make up a multilayer PCB are listed below:
- Signal layer: mainly used to place PCBA components or for wiring and soldering. It is divided into the top layer, middle layer and bottom layer.
- Internal power supply: Usually we also call it the internal electrical layer, which is specially used to arrange power lines and ground lines.
- Mechanical layer: Place physical dimension lines, data, via information and other indicative information for manufacturing PCBA boards.
- Solder Mask: A copper-free area used to place pads or other objects, including top and bottom layers.
- Silkscreen layer: used to mark the outline, number, and other text information of components.
- System Work Layer: Used to display information that violates the multi-layer PCB design rule check.
Manufacturing Difficulty
- Alignment between layers: With more layers, the difficulty of achieving precise alignment between them increases, and the alignment tolerance between layers is typically controlled at ±75μm. This challenge arises due to various factors, including size variations, substrate material properties, ambient temperature differences, and positioning methods.
- Inner layer manufacturing: When customers seek a multilayer PCB manufacturer, they often assess the materials the manufacturer can provide. These materials are usually required to have high thermal resistance (TG), high-speed characteristics, high-frequency capabilities, thick copper, and thin dielectric layers. Working with higher-end materials can pose challenges for manufacturers during inner layer circuit production and graphic size control, leading to issues such as low pass rates, open circuits or short circuits, missing tests in inner layer AOI (automated optical inspection), and poor exposure.
- Lamination: During lamination, when multiple inner core boards and semi-cured sheets are stacked, manufacturing defects like slippage, delamination, resin voids, and air bubble residue may occur. To prevent such problems, it is crucial to consider the heat resistance and voltage resistance of the materials and establish a reasonable multi-layer PCB lamination program.
Delivery and Cost
Errors are likely to come up if your boards are not checked properly and many designers usually work in a team to cross-verify their designs before sending them to production as troubleshooting faults may be very time-consuming and costly. In addition, multilayer PCB is typically more expensive when it comes to professional manufacturing and ordering the boards and will take more time to manufacture than ordinary two-layer PCB.
This may be due to the extensive functional checking & tests that need to be performed on the boards before they are ready to be produced, as correcting errors post-production is simply not feasible. Therefore, it is advisable that, before you order a multilayer PCB, a thorough check of the manufacturer is performed to ensure that the requirements set by the company match the requirements for your order.
Multilayer Circuit FAQ
Of course, FS Technology is a Chinese multi-layer PCB supplier facing the world, no matter where you are, we will provide you with the best quality service.
We are not a company that attracts clients on price, but on quality of service. If you want to get our service, please contact us by email, we will provide you with multilayer PCB pricelist immediately.
As the number of layers increases, the failure rate also rises. To prevent such issues, in addition to routine inspections, we employ various internal control measures to enhance production quality. These include First Article Inspection, manufacturing process control, and continuous monitoring and improvement.
For most circuit types, FS technology can realize the construction of multi-layer structure, but it may be difficult for ceramic PCB. If your project requires the use of ceramic slabs and requires multiple layers then we will build it for you using Rogers Corporation laminates.
First, engineers stack each single-layer or double-layer PCB according to the design requirements. Then, the stacked PCB is placed in a hot press for compression. Under high temperature and pressure, the pre-impregnated resin in the laminated material melts and bonds with the copper foils and hole walls of each layer, creating a strong connection.
When faced with complex designs or high-density layouts, FS Technology recommends using a multi-layer circuit structure, which can help avoid electromagnetic interference and implement effective thermal management.
Summarize
As mentioned briefly above, multilayer board is widely used in many consumer electronic PCB, ranging from mobile phones to graphic cards, and even state-of-the-art medical equipment. The compactness, reliability, and durability of multilayer PCBs make them highly suitable for these applications, particularly in industrial settings where versatility, consistency, and high performance are crucial. Additionally, multilayer PCB find applications in aerospace technology, navigation equipment (GPS), communications (radios), automotive machinery, and military-grade equipment. However, the use of multilayer PCB in industrial applications does not imply that they should not be considered for other electronic projects. Before choosing the route of multilayer PCBA, it is essential to weigh the pros and cons and be well-informed about both your design and the manufacturer of your PCBA. Nevertheless, single or double-layer PCB still have their place in the electronics industry and may be ideal for various applications that do not require the complexity of multilayer PCB.
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