The history of single-sided circuit boards:

Single sided printed circuit boards were developed in the early 1950s with the introduction of transistors in the United States. At that time, the main manufacturing method was direct etching of copper foil. From 1953 to 1955, Japan first used imported copper foil to make paper phenolic copper foil substrates, which were widely used in radios. In 1956, after the emergence of Japanese circuit board manufacturers, the manufacturing technology of single panels rapidly developed.

In terms of information, paper phenolic copper foil substrates were mainly used in the early stage, but due to the low electrical insulation, poor welding heat resistance, distortion and other factors of phenolic raw materials at that time, paper epoxy resin, glass fiber epoxy resin and other raw materials were continuously developed. Nowadays, single-sided boards required for consumer electronic machines simply use paper phenolic substrate boards.

Characteristics of single panel:

A single panel is on a basic PCB, with components gathered on one side and wires gathered on the other side. Because the wires are only present on one side in between, we call this type of PCB a single-sided board. Because there are many strict constraints on the planning of single panel circuits (because as long as there is only one side, wiring cannot be interspersed and it is necessary to go through separate paths), such boards are only used in the early stages of the circuit;

The wiring diagram of a single panel is mainly based on screen printing, which involves printing a resist on the copper surface, etching it, marking it with solder mask, and then using punching processing to complete the part guide hole and shape. In addition, some products produced in small quantities and with diverse styles are photographed using photoresist to create patterns.

Double sided circuit board

Double Sided Boards have wiring on both sides. However, to use wires on both sides, it is necessary to have appropriate circuit connections between them. The 'bridge' between these circuits is called a via. A through-hole is a small hole filled or coated with metal on a PCB, which can be connected to wires on both sides. Because the area of a double-sided panel is twice as large as a single panel, and because the wiring can be staggered (able to wrap around the other side), it is more suitable for use in circuits that are more cluttered than a single panel.

Strictly speaking, double-sided board is an important type of PCB board in the circuit board industry. Its usefulness is significant. It is easy to determine whether a PCB board is a double-sided board. Trusting friends can fully grasp the knowledge of a single panel. A double-sided board is an extension of a single panel, meaning that the circuit on the single panel is not enough and then turns to the opposite side. Another important feature of a double-sided board is the presence of conductive holes. Simply put, it's double-sided wiring, with lines on both sides! A board with double-sided wiring is a double-sided board! Some friends may ask, for example, if a board has double-sided wiring, but as long as one side has electronic components, is this board a double-sided board or a single panel? The answer is significant, this type of board is a double-sided board, just with parts attached to the double-sided board.

Simple differentiation of multi-layer circuit boards

The process difficulty and processing price of circuit boards are determined by the number of wiring surfaces. Ordinary circuit boards are divided into single-sided wiring and double-sided wiring, commonly known as single panel and double-sided board. However, for electronic products, due to the limitations of product space planning elements, in addition to external wiring, multiple layers of circuits can be stacked inside. During the production process, after each layer of circuit is manufactured, it is then positioned and pressed by optical equipment to stack multiple layers of circuits on one circuit board. be commonly called. Any circuit board with more than or equal to 2 layers can be called a multi-layer circuit board. Multilayer circuit boards can be divided into multi-layer rigid circuit boards, multi-layer soft hard circuit boards, and multi-layer soft hard combination circuit boards.

The birth of multi-layer circuit boards

Due to the increase in packaging density of integrated circuits, there is a high concentration of interconnects, which makes the use of multiple substrates a challenge. In the layout of printed circuits, unforeseeable planning issues such as noise, stray capacitance, crosstalk, etc. are presented. Therefore, it is necessary to focus on reducing the length of signal lines and preventing parallel routing in the planning of printed circuit boards.

Obviously, in single panel and even double-sided panels, these requirements cannot be met due to the limited number of insertions that can be achieved. In many cases where there is a need for interconnection and interpenetration, it is necessary to expand the board layers to two or more layers in order to achieve a satisfactory function, thus presenting a multi-layer circuit board.

Therefore, the original intention of manufacturing multi-layer circuit boards is to provide more freedom in selecting suitable wiring paths for cluttered and/or noisy electronic circuits. A multi-layer circuit board has at least three conductive layers, with two layers on the outer surface and the remaining layer integrated into an insulating board. The electrical connection between them is usually achieved through plated through holes on the cross-section of the circuit board. Unless otherwise specified, multi-layer printed circuit boards are the same as double-sided boards, generally plated with through-hole boards.

Multi substrate is manufactured by stacking two or more layers of circuits on top of each other, with reliable pre-set interconnections between them. Due to the completion of drilling and electroplating before all layers are rolled together, this technology has violated traditional manufacturing processes from the beginning. The inner two layers are composed of traditional double-sided panels, while the outer layer is different in that they are composed of independent single panels. Before rolling, the inner substrate will be drilled, plated through holes, transferred patterns, developed, and etched. The outer layer of the drilled hole is the signal layer, which is plated through by forming a balanced copper ring on the inner edge of the through-hole. Subsequently, each layer is rolled together to form a multi substrate, which can be connected to each other (between components) using wave soldering.

Rolling may be completed in a hydraulic press or in an overpressure chamber (autoclave). In hydraulic presses, prepared materials (for pressure stacking) are placed under cold or preheated pressure (materials with high glass transition temperature are placed at a temperature of 170-180 ℃). The glass transition temperature is the temperature at which the amorphous region of an amorphous polymer (resin) or partially crystalline polymer changes from a hard, moderately brittle state to a viscous, rubbery state.

The application of multi substrate is in specialized electronic equipment (computers, military equipment), especially in situations where the weight and volume are overloaded. However, this can only be achieved by increasing the cost of multiple substrates in exchange for a reduction in space and weight. In high-speed circuits, multiple substrates are also very useful as they can provide printed circuit board planners with more than two layers of board surface to lay wires and provide large grounding and power supply areas.

Article source: Jiangmen single-sided and double-sided circuit boardhttp://www.yonghongpcb.com/