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PCB heat dissipation design In modern electronic devices, as the integration level of integrated circuits increases and the operating frequency continues to rise, power consumption also increases accordingly, and heat dissipation issues become increasingly prominent. Good PCB heat dissipation design is crucial for ensuring the stability, reliability, and prolonging the service life of electronic devices. PCB heat dissipation design mainly starts from the following aspects: Firstly, it is necessary to arrange the components reasonably. Arrange components with high heat generation at the edges of the PCB or near ventilation openings as much as possible to facilitate heat dissipation. At the same time, avoid placing multiple high heat components together to prevent the formation of local hotspots. When laying out electronic components, the path of air flow should also be considered to ensure that the air can flow smoothly through the heating components and take away the heat as much
Process flow of single-sided and double-sided multi-layer circuit board 1. The process flow of single-sided circuit board cutting and edge grinding → drilling → outer layer graphics → (full board gold plating) → etching → inspection → silk screen solder mask → (hot air leveling) → silk screen characters → shape processing → testing → inspection. 2. The process flow of double-sided circuit board tin spraying is as follows: cutting and grinding the edges → drilling → copper sinking and thickening → outer layer graphics → tin plating, etching and tin removal → secondary drilling → inspection → silk screen solder mask → gold-plated plug → hot air leveling → silk screen characters → shape processing → testing → inspection. 3. The process flow of double-sided circuit board nickel plating and gold plating includes cutting and grinding edges, drilling holes, copper sinking and thickening, outer layer graphics, nickel plating and gold film etching, secondary drilling, inspection, silk scre
Copper coating conditions for PCB circuit boards (1) For boards that require strict impedance control, do not apply copper as it can affect impedance control due to the distributed capacitance between the copper and the wiring; (2) For devices and PCBs with high wiring density in the upper and lower layers, copper plating is not necessary. At this time, the copper plating is fragmented and basically ineffective, and it is difficult to ensure good grounding; (3) For single-sided and double-sided power boards, it is important to ensure that the power cord is connected to the ground wire and not to use copper plating. If copper plating is used, it will be difficult to ensure a proper circuit; (4) If it is a PCB with more than 4 layers (excluding 4 layers), and the second layer and the second to last layer are complete ground planes, copper plating is not necessary. However, if the device and wiring density of the upper and lower layers are small, copper plating is better; (5) If th
What to pay attention to when cooperating with circuit board manufacturers 1、 Pay attention to doing a good job in sampling work The production of any product cannot be separated from the crucial sampling process, especially in equipment manufacturing such as circuit board production, which requires high technical investment. Any order for circuit board production of any size should be accompanied by the manufacturer to complete the preliminary sampling work. Then, the actual presentation effect of the sample product and the testing of various key indicators must be done well and confirmed, which is a guarantee for both the demander and the circuit board manufacturer themselves. 2、 Pay attention to the review of design drawings Before the circuit board production is put into formal production, we should provide all information related to the design of the batch of circuit boards. The circuit board manufacturer and their professional personnel should review the design drawings aga
BGA packaging has developed to be fully compatible with current soldering and assembly technologies. CSP or close pitch BGA have gate spacing of 0.5, 0.65, and 0.80mm, while plastic or ceramic BGA has relatively wider contact spacing (1.50, 1.27, and 1.0mm). BGA with coarse and dense spacing are less susceptible to damage than pin packaging ICs with dense spacing. The BGA standard allows for selective removal of contact points to meet specific I/O requirements. When establishing the contact point layout and pin distribution for BGA, the packaging developer must consider the chip design as well as the size and shape of the circuit chip (die). Another issue encountered when planning pin distribution is the orientation of the circuit chip. When suppliers use chip on board technology, they usually adopt a form where the circuit chip faces up. PCB sampling PCB board sampling PCB board sampling The structure of circuit board prototype components is not specified in industry standards an
Circuit board sampling is divided into rigid circuit boards, flexible circuit boards, and soft hard composite boards. A general PCB is called a rigid PCB, and the intuitive difference between a rigid PCB and a flexible PCB is that a flexible PCB can be bent. The common thicknesses of rigid PCBs include 0.2mm, 0.4mm, 0.6mm, 0.8mm, 1.0mm, 1.2mm, 1.6mm, 2.0mm, etc. The common thickness of flexible PCB is 0.2mm, and a thick layer is added behind the part to be soldered. The thickness of the thick layer varies from 0.2mm to 0.4mm. The purpose of understanding these is to provide structural engineers with a spatial reference when designing. Common materials for rigid PCBs include phenolic paper laminates, epoxy paper laminates, polyester glass felt laminates, and epoxy glass cloth laminates; Common materials for flexible PCB prototyping include polyester film, polyimide film, and fluorinated ethylene propylene film. According to the number of circuit layers, it can be classified into si
What are the requirements for PCB multi-layer circuit board sampling? Nowadays, various enterprises pay special attention to product quality. In the manufacturing industry, the improvement of product quality also plays an important role in the industry's reputation. PCB multi-layer circuit boards have good quality in the circuit board manufacturing industry. Therefore, many PCB multi-layer circuit board manufacturers will conduct multi-layer board sampling before production to verify whether the circuit design performance meets the requirements. The following is an analysis of the requirements for PCB multi-layer circuit board sampling? 1. Neat appearance. When making samples of PCB multi-layer circuit boards, it is necessary to ensure that the product has a smooth appearance without burrs, and that there are no bubbles or delamination between the sample wires and solder mask. Under such appearance cleanliness requirements, PCB multi-layer circuit boards can ensure better soldering
Why is green used in the production of PCB circuit boards? (1) Introduction of professional PCB circuit board production companies in China: Green ink is currently the most widely used and has the longest history, and it is also cheap in the current market. Therefore, green is widely used by manufacturers as the main color of their products. (2) Usually, during the production of PCB circuit boards by PCB sampling companies, there are several processes that must go through the yellow light chamber because the effect of green in the yellow light chamber is better than other colors, but this is not the main reason. When soldering components in SMT, the production of PCB circuit boards involves the process of applying solder paste and mounting, as well as the final AOI calibration lamp. These processes require optical positioning calibration, and a green background color is more effective for instrument recognition. What are the common colors used in the production of PCB circuit boar
How to distinguish the quality of ceramic circuit boards? Ceramic circuit board is a new type of circuit board based on electronic ceramics with various circuit elements attached to the outside. It is widely used in the manufacturing of the electronics industry and has become an important component in electronic product manufacturing due to its good thermal conductivity, strong high-voltage resistance, and stable chemical properties. With the increasing number of products using ceramic circuit boards, it requires certain skills to distinguish a high-quality ceramic circuit board from numerous manufacturers and brands. 1. Check the material parameters of the ceramic board. Due to the fact that ceramic circuit boards use ceramic substrates as the support board for this circuit, the quality of the material used in circuit board sampling has a significant impact on the performance and service life of ceramic circuit boards to a certain extent. Ceramic circuit boards with guaranteed qua
PCB component wiring rules 1. Within the area of ≤ 1mm from the edge of the PCB board and within 1mm around the mounting holes, wiring is prohibited; 2. The power cord should be as wide as possible and not less than 18mil; The signal line width should not be less than 12mil; The CPU input and output should not be less than 10mil (or 8mil); The line spacing shall not be less than 10 mil; 3. Normal through-hole not less than 30mil; 4. Dual in-line insertion: solder pad 60mil, aperture 40mil; 1/4W resistor: 51 * 55mil (0805 sticker); When inserting directly, the solder pad is 62mil and the aperture is 42mil; Infinite capacitor: 51 * 55mil (0805 sticker); During direct insertion, the solder pad is 50mil and the aperture is 28mil; 5. Please note that the power and ground wires should be as radial as possible, and the signal wires should not have looped wiring.
Common problems with RF circuits and digital circuits on the same PCB Insufficient isolation of sensitive lines and noise signal lines is a common problem. As mentioned above, PCB circuit boards have high swing and contain a large number of high-frequency harmonics in digital signals. If the digital signal wiring on the PCB board is adjacent to sensitive analog signals, high-frequency harmonics may couple over. The most sensitive nodes of RF devices are usually the loop filtering circuit of the phase-locked loop (PLL), the external voltage controlled oscillator (VCO) inductor, the crystal oscillator reference signal, and the antenna terminal. These parts of the circuit should be handled with special care. (1) Power supply noise Due to the fluctuation of input/output signals by several volts, digital circuits are generally acceptable for power supply noise (less than 50 mV). However, analog circuits are quite sensitive to power noise, especially to spike voltage and other high-freq
Several material classifications for PCB circuit boards PCB circuit board substrates from PCB prototyping manufacturers can be divided into several types based on quality, material, and fire rating: PCB circuit boards 94HB cardboard: The most common cardboard material, mostly used to make low-grade single panels, with a cheap price. Due to its lack of flame retardant properties, it cannot be used for a series of products with fire protection requirements such as power supplies. 94V0 cardboard: A cardboard material with flame retardant properties, which contains flame retardant additives in its composition compared to 94HB cardboard material. 22F single-sided composite substrate: single-sided semi fiberglass board. CEM-1 single-sided composite substrate: This material requires CNC drilling. CEM-3 double-sided composite substrate: Low end double-sided board material, belonging to semi fiberglass material. FR-4 epoxy resin glass fiber board: the most commonly used PCB board mater
The Importance of PCB Equipment In the PCB industry, PCB sampling has the saying of "three parts technology and seven parts equipment", which well points out the important position of instrument equipment in the competition of the PCB industry. PCB equipment, as an important link in the PCB industry chain, directly affects the product quality of circuit boards. Therefore, in order for China's PCB industry to become stronger and bigger, the most important thing is to develop the instruments and equipment related to the PCB industry. Today, the editor will analyze the importance of PCB instrument equipment for everyone. One of the reasons why Chinese PCBs are not strong enough is that the high-end instruments and equipment in the PCB industry are still lagging behind. The accuracy, performance, and reliability of domestic instruments and equipment still have a gap with foreign ones, which leads to many of our PCB instruments and equipment still relying on imports. Not only are we fas
PCB suppresses interference sources Suppressing interference sources means minimizing their du/dt and di/dt as much as possible. This is the top priority and most important consideration in anti-interference design The principle often achieves twice the result with half the effort. Reducing the du/dt of the interference source is mainly achieved by paralleling capacitors at both ends of the interference source To achieve. Reducing the di/dt of the interference source is achieved by connecting an inductor or resistor in series with the interference source circuit and adding a freewheeling diode. The common measures to suppress interference sources are as follows: (1) Add a freewheeling diode to the relay coil to eliminate the back electromotive force interference generated when the coil is disconnected. Only adding a freewheeling diode will By delaying the disconnection time of the relay and increasing the voltage regulator diode, the relay can operate more times per unit time.
Characteristics of Circuit Board Assembly Integrated Circuit With the continuous development of technology, integrated circuits have gradually become a widely used circuit mode for circuit board assembly. So, what is the reason why integrated circuits are so popular? This starts with its characteristics. Integrated circuits for circuit board assembly have the advantages of small size, light weight, fewer lead wires and solder joints, long lifespan, high reliability, and good performance. At the same time, they have low cost and are easy to mass produce. It is widely used not only in industrial and civilian electronic devices such as recorders, televisions, computers, but also in military, communication, remote control, and other fields. Using integrated circuits for circuit board assembly can increase the assembly density by tens to thousands of times compared to transistors, and greatly improve the stable working time of equipment.
Professional PCB manufacturers' standards for printed circuit boards 1. IEC60326-4 (1996-12) Printed boards - Part 4: Internally connected rigid multilayer printed boards - Sectional specification. 2. IEC60326-4-1 (1996-12) Printed boards - Part Y4: Internally connected rigid multilayer printed boards - Sectional specifications - Part Y: Detailed specifications for capabilities - Performance levels A, B, C. 3. IEC60326-3 (1991-05) Printed boards - Part 3: Design and use of printed boards. 4. IEC60326-4 (1980-01) Printed Boards - Part 4: Specification for Single sided and Double sided Ordinary Printed Boards (this standard was revised Y times in November 1989). 5. IEC60326-5 (1980-01) Printed Boards - Part 5: Specification for Single sided and Double sided Ordinary Printed Boards with Metallized Holes (Yth Revision, 1989). 6. EC60326-7 (1981-01) Printed boards - Part 7: Specification for single and double-sided flexible printed boards (without metalized holes) (revised Y in Nove
Wave soldering technology 1： Wave soldering is the process of forming a specific shape of solder wave on the liquid surface of a solder tank using molten liquid solder and the action of a pump. The solder wave is then placed on a PCB with electronic components and transported on a chain, passing through the solder wave at a specific angle and immersion depth to achieve solder joint soldering. PCB circuit board 2： Wave crest surface: The surface of the wave is covered by a layer of oxide skin, which remains almost static along the entire length of the solder wave. During the wave crest soldering process, the PCB comes into contact with the leading surface of the tin wave, causing the oxide skin to break and pushing the tin wave in front of the PCB forward without any cracks or wrinkles 3： Solder joint formation: When the PCB enters the front end (A) of the wave crest, the substrate and pins are heated, and before leaving the wave crest (B), the entire PCB is immersed in solder, bri
The detachment between the copper holes on the circuit board and the copper substrate, and even the continuity at the corners of the interface Causing increased pollution of the neutralization tank by potassium permanganate, and poor water washing after removing the gel with potassium permanganate. Greatly reducing the service life and neutralization effect of the neutralization tank, resulting in residual potassium permanganate in the hole, affecting the subsequent copper deposition effect, causing some potential quality problems, poor copper deposition backlight, poor hole wall adhesion, no copper in the hole, hole wall detachment, blowing holes, bursting holes, etc; In addition, when the circuit board is more serious, excessive potassium permanganate will react with the neutralizing agent in the tank solution and produce a pale yellow substance, which will then adsorb onto the hole wall or inner copper ring, causing quality hazards such as poor inner layer connections, open circu
In PCB board sampling, Rx is a resistor. There are many resistors in the circuit diagram, arranged in sequence, R1, R2... Cx is a non-polar capacitor, an anti-interference capacitor at the power input end IC integrated circuit module Ux is an IC (Integrated Circuit Component) Tx is a testing point (used for factory testing) Spk1 is a speaker (buzzer, horn) Qx is a transistor CEx electrolytic capacitor, CNx discharge capacitor, RNx discharge resistor, CONx connector, Dx diode, Lx inductor/magnetic bead, LEDx light-emitting diode, Xx crystal oscillator. RTH (Thermistor) CY (Y capacitor: high-voltage ceramic capacitor, safety standard) CX (X capacitor: high-voltage thin film capacitor, safety regulations) D (diode) W voltage regulator tube K switch type Y crystal oscillator R117: The resistor on the motherboard, serial number 17. T101: Transformer on the motherboard. SW102: Switch LED101: Light Emitting Diode LAMP: (indicator) light Q104 (E, B, C): transistor, E: e
There are several commonly used copper-clad laminates, including the following There are also many types of copper-clad laminates. According to different insulation materials, it can be divided into paper substrate, glass cloth substrate, and synthetic fiber board; According to the different adhesive resins, they can be divided into phenolic, epoxy, polyester, and polytetrafluoroethylene, etc; It can be divided into general and special types according to its purpose. The structure and characteristics of commonly used copper-clad laminates in China (1) Copper foil phenolic paper laminated board is a laminated product made by impregnating insulation impregnated paper (TFZ-62) or cotton fiber impregnated paper (1TZ-63) with phenolic resin and hot pressing. The two surfaces of the adhesive paper can be attached with a single alkali free glass impregnated tape, and one side is coated with copper foil. Mainly used as printed circuit boards in wireless equipment. (2) Copper clad phenoli
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