PCBs are generally divided into single-sided, double-sided, and multi-sided according to the number of layers. The so-called standard boards generally refer to double-sided and single-sided boards. Multilayer boards are divided into HDI and high-level multilayer boards according to variant engineering methods.
Those are the most basic printed circuit boards; all parts are concentrated on one side, while the wires are concentrated on the other.
Double Sides PCBs
Double-sided PCBs(Double-sided Printed Circuit Boards) are another traditional PCB with higher complexity than single-side ones. Double Sides PCBs’ architecture needs plating through holes between the bottom and top pads to provide better anchoring for soldered components. Today double-sided printed circuit board technology remains the workhorse of the assembly industry. There are unlimited applications for double sides PCBs. Fine line surface mount, ultra-high copper build, high/ low temperature, solder coating, and silver and gold finishes are a few common double-sided board applications.
Multi-layer PCBs consist of at least three or more circuit layers bonded by an insulating material called prepreg and core thickness. Multilayer printed circuit boards are the most complicated ones and are generally used on the most sophisticated electronic product with their complexity in architecture and construction methods.
Printed circuit boards have developed from single-layer to double-sided, multilayer, and flexible boards. And continue migration toward highly precise, high density, and high-reliability features. Parallel with shrinking size, reducing cost, and improving performance, printed circuit boards still maintain a strong vitality in the development of electronic products in the future.
From the 1950s to the 1990s, the PCB industry was founded and grew rapidly, that is, the early stage of PCB industrialization, when PCB became a separate industry.
In the 1950s, transistors were used in electronic devices, which helped to effectively reduce the size of electronic products and made it easier to integrate PCBs. In addition, engineers have made significant progress in improving the electronic reliability of PCBs.
In 1953, Motorola developed a double-sided board with plated vias. Around 1955, Toshiba of Japan introduced the technology to generate copper oxide on the surface of copper foil, and copper-clad laminates (CCLs) appeared. Thanks to these two technologies, multilayer circuit boards were invented successfully and applied on a large scale.
In the 1960s, printed circuit boards were widely used, PCB technology became increasingly advanced, and due to the widespread use of multilayer printed circuit boards, the ratio of wiring to substrate area was effectively increased.
In the 1970s, multilayer PCBs developed rapidly, pursuing higher precision and density, fine-line holes, high reliability, lower cost, and automated production. At that time, PCB design work was still done by hand. PCB Layout engineers use colored pencils and a ruler to draw circuits on clear mylar. They made several packaging and circuit templates for some common devices to improve drawing efficiency.
In the 1980s, Surface Mount Technology (SMT) gradually replaced through-hole mounting technology as the mainstream. It also entered the digital age.
With the evolution of electronic devices such as personal computers, CDs, cameras, game consoles, etc., correspondingly have changed considerably. The size of the PCB must be reduced to accommodate these small electronic devices. Computerized design automates multiple steps of PCB design and makes designing small and light components easier. Regarding component suppliers, they also need to improve their equipment by reducing power consumption, but at the same time, they need to consider the issue of cost reduction.
In the 2000s, PCBs became more complex, functional, and smaller. Especially multilayer and flexible circuit PCB designs made these electronic devices more maneuverable and functional, with small size and low-cost PCB. The advent of smartphones boosted the development of HDI PCB technology. While retaining laser-drilled microvias, stacked vias began to replace interleaved vias, and combined with “any layer” construction techniques, HDI boards resulted in final line widths/lines. The distance reaches 40μm.
This arbitrary-layer approach is still based on a subtractive process, and it is certain that for mobile electronics, most high-end HDIs are still using this technology. However, in 2017, HDI entered a new development phase, shifting from subtractive processes to Processes based on pattern plating.
The application of standard PCBs is relatively used on low-end electronics products. Those PCBs are made from general-purpose materials, and the design of PCBs is not complicated and can be applied to various industries.
Home Appliances: Small household appliances, flashlights, audio, TV, routers, washing machine, etc.,
Medical Equipment: some equipment is used multi PCBs, while some cutting edge devices may use a separate basic PCB. Medical applications include heartbeat sensors, temperature measurements, MRI equipments, CT scanners, blood pressure machines, pH meters, X-ray machines, blood sugar measurement devices, etc.
Consumer Electronics: Consumer electronics pursue the ultimate in the use of PCBs. Most fully competitive consumer electronics products integrate as many functions as possible through the smallest area design and the most simplified PCB design， the most simplified PCB design, and provide the competitiveness of consumer electronics products. In low-end consumer electronic products, many single-layer or double-layer boards are used, while in high-end mobile phones, HDI boards are widely used.
Engineering Equipment. Almost all manufacturing equipment driven by power needs multi-functional PCBs. Usually, these types of equipment operate on high power and require high-current circuit drives, such as large servo motor drives, clothing cotton machines,lead-acid battery chargers, etc.
Lighting. LED lights and high-intensity LEDs are surfaces mounted on a PCB based on an aluminum substrate; aluminum has the feature of absorbing heat and dissipating it.
Automotive and Aerospace Flexible PCBs are lightweight but can withstand high vibrations, and they can be bendable even in limited spaces, reducing the aircraft’s weight. These PCBs are used as connectors or interfaces and can be assembled even in narrow and limited spaces, such as under dashboards and behind panels, etc.
Standard PCBs are different in technology and complexity. Generally speaking, manufacturers that can produce standard PCB boards may not be able to produce multilayer boards, and manufacturers that can produce multilayer boards must be able to produce standard boards. Most manufacturers that can only produce standard boards are small in scale, with backward equipment and unstable quality. Still, they can provide competitive quotations. While multilayer board/HDI manufacturers are large in scale, advanced in equipment, and stable in quality, their prices are relatively high.
Once a customer has PCB manufacturing needs, he must understand the needs of the PCB, including application, the demand, and the number of layers. Then search and match the corresponding PCB suppliers according to the number of layers and categories. Suppose the customer’s demand is for some very low-end consumer electronic products. Price is the dominant criterion for winning the award. Since, in that case, most of the ordinary standard PCB suppliers can meet the demand. But when it comes to multilayer boards and non-consumer electronics applications, we strongly recommend that customers choose a qualified PCB factory with a certain scale. In addition to comparing quotations, it is also necessary to check the PCB factory’s qualifications and production and processing capabilities. Besides the information introduction from PCB suppliers, customers can understand the capabilities of the PCB factory through the professional feedback of EQ.
What equipment will be used in PCB production?
Generally, more than 40 processes are needed in a standard PCB production, while up to 70-80 processes are needed to complete complex PCBs. The whole process needs to involve a lot of expensive equipment like an automatic exposure machine, AOI, horizontal electroplating line, green oil DI machine, drilling rig, laser drilling rig, gong machine, E-TEST, VCP, and other equipment.
What is the traditional manufacturing process of PCB?
PCB manufacturing is configured by Inner Board manufacturing and out layer board production.
|Quality Grade||Standard IPC 2|
|Number of Layers||1 – 32layers|
|Material||FR-4(TG135/TG150/TG170/CAF>600/Halogen Free)/PTFE(SY/Rogers) R-F PCB(IT/Taihong/Dupont/Panasonic)|
|Max Board Size||Max 520mm x 850mm|
|Final Board Thickness||0.25mm – 7.0mm|
|Board Thickness Tolerance||±0.1mm – ±10%|
|Final Board Thickness||0.4mm – 7.0mm|
|Inner Layer Cooper Thickness||0.5oz – 4.0oz|
|Outer Layer Cooper Thinkness||0.5oz – 8.0oz|
|Min Hole Diamete – Mechanical||6mil|
|Min Hole Diamete – Laster||3mil|
|Hole Size Tolerance||±.002″ (±0.05mm)|
|Solder Mask Color||Green, Red, Yellow, Blue, White, Black, Purple, Matte Black, Matte green|
|Silkscreen Color||White, Black, Yellow,Red, Blue|
|Surface Traatment||HASL, Hard Gold Finger, OSP, Immersion Gold, Immersion Tin, Immersion Sliver|
|Gold Thinkness-Immersin Gold||0.025-0.075um|
|Gold Thinkness-Hard Gold||<1.27um|
|Testing||Fly Probe Testing (Free) and A.O.I. testing|
|Lead Time||2 – 28days|