HDI PCB - Custom PCB

A custom pcb is a circuit board that is tailored to specific needs and design specifications. It is not only a component within an electronic device, but also a key to the smooth functioning of the entire system, connecting the electronic components with precision and ensuring the accurate transmission of currents and signals. Whether for smartphones, computers, medical devices or automotive electronic control systems, they all rely heavily on high-quality customised circuit boards.

Custom pcb design process:

Requirements clarification: The first step is to have an in-depth conversation with the customer or project team to clearly define the functional requirements of the board, such as whether it is to be used for power regulation, signal processing or as a platform for a microcontroller. At the same time, it is important to define the environmental conditions under which the board will operate, covering factors such as temperature range, humidity levels, and the presence or absence of electromagnetic interference. In addition, it is also critical to understand the size constraints of the product and how it will be mounted. For example, handheld devices require compactness and portability, while circuit boards in industrial control cabinets may be more relaxed about size, but have higher requirements for stability and protection.

Circuit diagram design:

Component Selection: Careful selection of electronic components based on functional requirements. For example, in the power supply circuit design, according to the required voltage and current to select the appropriate power supply chip, capacitors and inductors and other components. In audio amplifier circuit design, it is necessary to select the appropriate performance of the audio amplifier chip, and consider its gain, bandwidth and distortion and other key parameters.

Schematic drawing:Use professional electronic design automation (EDA) tools,such as Altium Designer or Cadence OrCAD, to accurately connect components according to circuit logic. When drawing, it is necessary to pay attention to the accuracy of the electrical connection between the components,reasonable planning of the signal flow,and try to reduce the signal crossover and interference. For example, high-speed digital signals and analogue signals should be wired separately to prevent digital signals from interfering with analogue signals.

PCB layout planning:

Component positioning: the schematic components are reasonably placed on the PCB board.Usually the first location of key components, such as microcontrollers and power devices. For components that require heat dissipation, it is necessary to consider the path of its heat dissipation, placed in a well-ventilated or easy to install the location of the heat sink. For example, high-power MOSFETs should be located close to heatsinks and avoid placing temperature-sensitive components around them.

Wiring considerations: Follow the wiring rules for component layout to facilitate wiring and place components with frequent connections close to each other. At the same time, it is necessary to follow the electromagnetic compatibility (EMC) principles, the components that may generate electromagnetic interference and sensitive components are separated from the layout. For example, high-frequency oscillating components such as crystals should be kept away from analogue signal input and output pins to prevent electromagnetic radiation from interfering with other signals.

PCB wiring implementation:

Rule Setting:Before wiring,need to be set in the EDA software wiring rules, including line width,line spacing and over-hole size.For example,the power and ground lines usually need to be widened to adapt to the high current through and reduce the resistance.High-speed signals require appropriate line spacing to prevent signal crosstalk.

Wiring operation:According to the signal type and importance of wiring. Prioritise power and earth wires to ensure power integrity and stability.High-speed digital signals should be wired with the shortest path to reduce transmission delay and reflection.At the same time, pay attention to the wiring of differential signals and keep the length and spacing of differential pairs consistent to improve signal quality. For example, when wiring high-speed USB interface circuits,differential signal wiring requirements need to be strictly adhered to.

Design rules and electrical rules check:Use the checking function of EDA software to conduct a comprehensive review of the PCB design.Design rule check (DRC) is mainly to verify the physical rules, such as line width and component spacing to meet the requirements. Electrical Rules Check (ERC) verifies the correctness of the electrical connections, such as whether there are short circuits or open circuits and other issues.Errors are corrected in a timely manner to ensure that the board is trouble-free in manufacturing and in actual use.

Manufacturing Documentation: After the design has passed inspection,the circuit board is manufactured using documentation such as Gerber files,which contain the board's graphics and drilling information and are the main basis for the manufacturer's production.Assembly files are also generated to guide component installation, including the component list (BOM) and component location diagrams.

Key Technologies for custom pcb:

Electromagnetic Compatibility (EMC) Planning

Shielding technology application: Shielding shells can be deployed for circuit areas that are susceptible to or generate electromagnetic interference. For example, installing metal shielding shells around RF circuits can effectively isolate internal circuits from external electromagnetic fields, while preventing internal RF signals from leaking out and causing interference to other circuits.

Filter circuit design: Integrate filter circuits at the power input and signal input and output ports. For example, a π-type filter circuit consisting of capacitors and inductors is configured on the power line, which can effectively filter out high-frequency noise in the power supply and improve the purity of the power supply. For signal ports, suitable filters, such as low-pass, high-pass or band-pass filters, should be selected according to the frequency and characteristics of the signal.

Signal Integrity Guarantee

Terminal matching strategy: For high-speed digital signal transmission lines, implement a terminal matching strategy to prevent signal reflection. For example, in the wiring design of high-speed DDR memory interfaces, termination matching is carried out by connecting resistors and capacitors in series or parallel to ensure that the signal is accurately transmitted to the receiving end and to reduce signal distortion.

Signal delay control: In complex circuit board design, signal transmission delay needs to be closely monitored. Through fine wiring and component position adjustment, try to make the delay of the relevant signals remain consistent. For example, in synchronous digital circuits, if the clock signal and data signal transmission delay difference is too large, will lead to data reading errors. Therefore, the delay difference needs to be reduced by means such as precise control of the wiring length.

Power Integrity Optimisation

Power and ground plane design: in the multi-layer PCB design, the need for rational planning of the power plane and ground plane. These planes can provide low-impedance power and ground loops, effectively reducing power supply noise. For example, in the digital circuit system, the digital power supply and digital ground are set up as separate planes, and through a number of vias and components of the power supply pins and ground pins connected to ensure the stability of the power supply.

Decoupling Capacitor Deployment: Decoupling capacitors are configured near the power pins of each integrated circuit (IC). These capacitors can quickly provide the required charge when the chip is operating, reducing power fluctuations. A combination of 0.1uF and 10uF capacitors is usually chosen, where the 0.1uF capacitor is used to filter out high-frequency noise and the 10uF capacitor provides a larger charge reserve.

Advantages of custom pcb:

Custom pcb can be designed and manufactured according to the customer's detailed requirements in order to achieve unique customisation. Whether in terms of dimensions, stack-up structures, impedance adjustments or special process requirements, customised boards can be precisely matched to the customer's specific requirements, ensuring optimum performance and quality.

In addition, custom pcb brings increased productivity and shorter lead times. By working with a professional custom pcb manufacturer, customers are able to flexibly adjust order sizes and delivery times according to their own production planning and needs, thereby gaining more control over the production process, accelerating production efficiency and cutting production costs.

Custom pcb also offers superior technical support and after-sales maintenance services. Compared to standardised boards, custom pcb often provides more comprehensive technical support services, including design optimisation strategies, process improvement solutions, etc., which help customers to properly solve various problems encountered in the production process and enhance product reliability and stability. The core advantages of customised circuit boards are reflected in the personalisation, efficient production process and excellent service. By establishing a partnership with a professional manufacturer of customised PCB circuit boards, customers are able to enjoy a higher level of product quality and a more satisfactory service experience, providing a solid backing for the development and manufacture of electronic products.

When developing a cost budget, factors such as the material, quantity, complexity, and production cycle of the circuit board need to be taken into account. The cost can be effectively suppressed by choosing the right size of boards, reducing the number of layers, and redesigning the modules of the custom pcb.

1.Board selection Board selection is one of the most important factors in the cost of a custom circuit board. For example, the price of FR-4 boards, aluminium substrates and ceramic substrates varies greatly. Choosing the right size board to avoid waste and choosing a more competitive board of the same type can effectively keep costs down.

2.Layer Reduction When designing circuit boards, we can consider reducing the number of layers to reduce costs. In order to ensure that the design requirements, reduce the number of layers of the circuit board can reduce the difficulty of manufacturing, but also to reduce the amount of material used to reduce manufacturing costs.

3.Modular design in the design of circuit boards, the use of modular design ideas can help reduce costs. Certain modules are directly customised into system boards, power supply boards, conversion boards, etc., which can reduce the operation of the production line, improve efficiency and reduce manufacturing costs.

4.Production cycle production cycle is also an important factor in the cost of custom pcb.When developing the cost budget, we need to consider the impact of the manufacturing cycle. If the production cycle of custom pcb is relatively short, you need to plan the machines on the production line and adopt advanced equipment and process technology to ensure accuracy and efficiency. This avoids long waiting times and costly expediting fees.

Custom pcb is an indispensable core component of electronic devices due to their high degree of customisation, high performance and efficient production. Through meticulous design and cost-control strategies, we not only ensure superior product quality, but also enhance market competitiveness.