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เซินเจิ้นผู้ผลิต PCB แนะนำ 8 PCB สัญญาณเส้นทางกฎ

2020-04-13

10 ข้อผิดพลาดที่คุณต้องหลีกเลี่ยงขณะออกแบบแผงวงจรพิมพ์


shenzhen pcb manufacturer set physical

ผู้ผลิต PCB ของเซินเจิ้น ความรู้ที่สำคัญของการกำหนดเส้นทางสัญญาณ PCB rules

ในฐานะผู้ผลิต PCB ของเซินเจิ้นคุณต้องมีความรู้มากมายสัญญาณความเร็วสูงเป็นหนึ่งในนั้น

สัญญาณความเร็วสูงคืออะไร?

If the signal’s rising edge time is less than 4 times the signal transmission delay. Moreover, we can regard it as a high-speed signal. At this time, we must use the method and means of the transmission line to analyze.

What characteristics should shenzhen pcb manufacturer follow?

Shenzhen pcb manufacturer

The characteristics of high-speed signals require that ผู้ผลิต PCB ของเซินเจิ้น must formulate constraint rules for key signals in the design, and the constraint rules drive layout. Next, let’s understand the routing rules of high-speed PCB signals.

High-speed pcb manufacturer signal routing rules

  1. Blocking rules

In the design of high-speed PCBs , the critical high-speed signal lines such as clocks and traces need to be shielded. If there is no shield or only part of the shield, it will cause EMI leakage. Similarly, it is recommended that the shielded wire be punched to the ground every 1000mil.

Second, closed-loop rules

Due to the increasing density of PCB boards, many ผู้ผลิต PCB ของเซินเจิ้น and LAYOUT engineers are prone to make mistakes during the routing process. That is:

  • High-speed signal networks such as clock signals
  • which produce closed-loop results when multilayer PCBs are routed
  • As a result of such a closed loop, a loop antenna will be produced, increasing the radiated intensity of EMI.
  1. Open-loop rules

Rule 2 mentioned that the closed-loop of high-speed signals will cause EMI radiation. But the open-loop will also cause EMI radiation. High-speed signal networks such as clock signals, once the result of open loops when ผู้ผลิต PCB ของเซินเจิ้น generates multi-layer PCB traces, will produce linear antennas, increasing the radiated intensity of EMI.

  1. 4. Continuous rule of characteristic impedance- ผู้ผลิต PCB ของเซินเจิ้น

Shenzhen pcb manufacturers

High-speed signal, when switching between layers must ensure the continuity of characteristic impedance. Otherwise, it will increase EMI radiation. In other words, the width of the wiring of the same layer must be continuous, and the impedance of the traces of different layers must be persistent.

  1. Rules of wiring direction

The wiring between the adjacent two layers must follow the principle of vertical wiring. Otherwise, it will cause crosstalk between the wires and increase EMI radiation. In short, the adjacent wiring layers follow:

  • the horizontal and vertical wiring directions
  • vertical wiring can suppress crosstalk between lines.
  1. Topology rules

In high-speed PCB design, there are two important points for ผู้ผลิต PCB ของเซินเจิ้น :

  1. the control of the characteristic impedance of the circuit board
  2. and the design of the topology under multiple load conditions directly determine the success or failure of the product.

7-resonance rules for shenzhen pcb manufacturer

 

Check whether the length of the signal line and the frequency of the signal constitute resonance. That is when the length of the wiring is an integer multiple of 1/4 of the signal wavelength. Simultaneously, the wiring will generate resonance, and the resonance will radiate electromagnetic waves and cause interference.

8-return path rules

A ผู้ผลิต PCB ของเซินเจิ้น should ensure that all high-speed signals must have a good return path. As far as possible, ensure that the return path of high-speed signals such as clocks is minimal.

Otherwise, the radiation will be greatly increased, and the size of the radiation is proportional to the area surrounded by the signal path and the return path.

Nine, the decoupling capacitor placement rules

The position of the decoupling capacitor is very important. Unreasonable placement will not have the effect of decoupling. The principle is: close to the pin of the power supply. And the area surrounded by the power supply trace and the ground of the capacitor is the smallest.

Some prominent pcb design rules recommended by expert ผู้ผลิต PCB ของเซินเจิ้น

  1. Device selection

Generally, device selection mainly refers to the selection of devices that are more advantageous in terms of:

  • Procurement
  • processing, and

For example:

  • try to use SOP devices instead of BGA devices;
  • use devices with large pitch and
  • do not use fine pitch devices
  • Furthermore,try to use conventional devices instead of special devices.

The DFM selection of the device, as a ผู้ผลิต PCB ของเซินเจิ้น and designer, needs to be negotiated with:

  • the procurement engineer
  • hardware engineer
  • process engineer, etc.

วิธีผู้ผลิต PCB ของเซินเจิ้น set physical parameters of pcb?

 

The main part of the physical parameters of PCB design is mainly determined by the shenzhen pcb manufacturer and designer. Mainly include setting of board thickness aperture ratio, line width spacing, stacking design, pad aperture, etc.

This requires PCB designers to have an in-depth understanding of the PCB manufacturing process and manufacturing methods.

  • Understand the processing parameters of most board factories.
  • And then set the physical parameters in combination with the actual situation of the single board.
  • Try to increase the PCB production process window
  • and use the most mature processing technology and parameters.
  • ลดความยุ่งยากในการประมวลผลปรับปรุงผลผลิตและลดต้นทุนและวงจรการผลิต PCB ในช่วงเวลาต่อมา

รายละเอียดการผลิตและการออกแบบ pcb

หลายสถานการณ์ในรายละเอียดการออกแบบ PCB มีส่วนเกี่ยวข้องกับระดับและประสบการณ์ของผู้ผลิต PCB ของเซินเจิ้นเช่น:

  • ตำแหน่งอุปกรณ์
  • ระยะห่าง
  • การเดินสายไฟ
  • การแปรรูปทองแดง ฯลฯ

พารามิเตอร์เหล่านี้ต้องการการสะสมในระยะยาวของหลายโครงการเพื่อให้ได้มา โดยทั่วไปแล้วการออกแบบอย่างมืออาชีพจะต้องเผชิญกับความต้องการของโรงงานบอร์ด PCB และโรงงานแปรรูปการเชื่อม

ดังนั้นโดยทั่วไปแล้วพารามิเตอร์การออกแบบจึงสามารถตอบสนองความต้องการของโรงงานผลิตบอร์ดส่วนใหญ่แทนที่จะเป็นไปตามข้อกำหนดด้านต้นทุนเฉพาะของโรงงานบางแห่ง

The rule of safe distance in PCB design is a very important key indicator. Moreover, it involves whether the PCB design process is beautiful and the function is perfect. As for the consideration of perfect function, it is also divided into electrical safety distance, mechanical structure safety distance.

Therefore, the rules of safe space and distance based on perfect function need to be thoroughly understood by ผู้ผลิต PCB ของเซินเจิ้น in order to effectively avoid these minefields in the design.

What spacing do you need to consider in pcb manufacturing and design?

   pcb manufacturing and design  

 There are many places in PCB design that need to consider the safety distance. Here, for the time being, it is classified into two categories:

  1. one is the electrical safety distance
  2. and the other is the non-electricity safety distance.

Electrical safety distance:

1. Spacing between wires

According to the spacing between the ผู้ผลิต PCB ของเซินเจิ้น processing capacity, and the lead wire cannot be lower than the minimum 4mil. The minimum line spacing is also the line-to-line and line-to- pad distance. From a production point of view, the larger the condition, the better. Generally, 10mil is more common.

  1. Pad aperture and pad width:
    According to the processing capabilities of mainstream PCB manufacturers, the pad aperture must be at least 0.2 mm if mechanically drilled. And at least 4 mil if it is laser drilled. Furthermore, the aperture tolerance is slightly different depending on the plate. Generally, we can control it within 0.05mm. The minimum width of the pad shall not be less than 0.2mm.

The layout methods of components in PCB design rules include:

  • component layout requirements
  • component layout sequenceand
  • common component layout methods
  • component layout principles

 

In PCB LAYOUT, when we use Protel, DXP, PADS, protel DXP and other tools to draw the circuit board, ผู้ผลิต PCB ของเซินเจิ้น need to pay attention to the following aspects:

Pcb Components layout requirements

A ผู้ผลิต PCB ของเซินเจิ้น should ensure the circuit function and performance index;

  • meet the requirements of manufacturability,
  • inspection, maintenance,
  • the components are neatly arranged, properly arranged and dense, taking into account the aesthetics.

Principle of pcb component layout

 

The arrangement direction should be consistent with the schematic diagram as much as possible. And the wiring direction should be consistent with the wiring direction of the circuit diagram. There are 5-10mm gaps around the PCB without devices.

  1. The layout of the components should be conducive to the heat dissipation of the heating components.
  2. when high frequency, consider forthe distribution parameters between components,
  3. the general circuit should arrange the components in parallel as much as possible.
  4. isolation between high and low voltage, isolation distance and withstand voltage.

For a single-sided PCB, each component pin occupies a pad alone. And the components cannot cross up and down. And a shenzhen pcb manufacturer should maintain a certain distance between adjacent two components, not too small or touching.

Component layout order

Place the components with larger areas first; integrate first and then separate; main first and then second, and place the main circuit when multiple integrated circuits.

ผู้ผลิต PCB ของเซินเจิ้น Layout method of commonly used components

 

  • A ผู้ผลิต PCB ของเซินเจิ้นshould place adjustable components on the printed board for easy adjustment
  • components with a mass of more than 15g should be supported by brackets.
  • High-power devices are best installed on the chassis floor of the whole machine.
  • The thermal components should be far away from the heating elements

For tubular elements, a pcb manufacturer generally places the device flat. But when the PCB size is not large, it can be placed vertically. The distance between the two pads when placed vertically is generally 0.1-0.2 in (1 in = 25.4 × 10 (-3 cubic) m). For integrated circuits, determine whether the orientation of the positioning slot is correct.

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