In design, layout is an important part. The quality of the layout result will directly affect the effect of the wiring, so it can be considered that a reasonable layout is the first step to a successful PCB design. Especially the pre-layout is the process of thinking about the entire circuit board, signal flow, heat dissipation, structure and other structures. If the pre-layout fails, no amount of effort will be needed.

PCB layout design The design process flow of printed circuit boards includes schematic design, electronic component database registration, design preparation, block division, electronic component configuration, configuration confirmation, wiring and final inspection. In the process of the process, no matter which process is found to be a problem, it must be returned to the previous process for reconfirmation or correction.

本文首先介紹了PCB版圖設計規則和技巧，然後從版圖的DFM要求、熱設計要求、信號完整性要求、EMC要求、層設置和電源地分割要求，解釋瞭如何設計和檢查PCB版圖。電源模塊。 需求等方面會詳細分析，跟著小編一起來了解詳情。

PCB佈局設計規則

1、一般情況下，所有的元器件都應排列在電路板的同一面上。 只有當頂層元件過於密集時，才能安裝一些高度有限、發熱低的器件，如貼片電阻、貼片電容、貼片電容等。 芯片IC等放置在下層。

2、在保證電氣性能的前提下，元件應放置在網格上，並相互平行或垂直排列，以整齊美觀。 一般情況下，組件不允許重疊； 元件的排列要緊湊，元件要排列在整個佈局上。 分佈均勻、密集。

3. The minimum distance between adjacent land patterns of different components on the circuit board should be above 1mm.

4、與電路板邊緣的距離一般不小於2MM。 電路板的最佳形狀為矩形，縱橫比為3:2或4:3。 當電路板尺寸大於200MM乘150MM時，考慮電路板能承受多大的機械強度。

PCB layout design skills

在PCB的佈局設計中，要分析電路板的單元，佈局設計要以啟動功能為主。 在對電路的所有元件進行佈局時，應滿足以下原則：

1、按電路流向佈置各功能電路單元的位置，便於信號流通，使信號盡可能保持在同一方向[1]。

2. Take the core components of each functional unit as the center and lay out around him. The components should be uniformly, integrally and compactly arranged on the PCB to minimize and shorten the leads and connections between the components.

3、對於高頻工作的電路，必須考慮元件之間的分佈參數。 一般電路中，元器件盡量並聯排列，不僅美觀，而且安裝方便，便於批量生產。

如何設計和檢查 PCB 佈局

1. DFM requirements for layout

1、最優工藝路線已經確定，所有器件都已經放置在板上。

2. The origin of the coordinates is the intersection of the left and lower extension lines of the board frame, or the lower left pad of the lower left socket.

3. The actual size of the PCB, the location of the positioning device, etc. are consistent with the process structure element map, and the device layout of the area with restricted device height requirements meets the requirements of the structure element map.

4、撥碼開關、復位裝置、指示燈等位置適當，手把不干擾周圍裝置。

5、板子外框光滑弧度197mil，或按結​​構尺寸圖設計。

6、普通板200億工藝邊； 背板左右兩側工藝邊緣大於400mil，上下兩側工藝邊緣大於680mil。 設備放置與窗口打開位置不衝突。

7. All kinds of additional holes (ICT positioning hole 125mil, handle bar hole, elliptical hole and fiber holder hole) that need to be added are all missing and set correctly.

8. 波峰焊處理過的器件管腳間距、器件方向、器件間距、器件庫等都考慮到了波峰焊的要求。

9. The device layout spacing meets the assembly requirements: surface mount devices are greater than 20mil, IC is greater than 80mil, and BGA is greater than 200mil.

10、壓接件在元件表面距離上有120mil以上，焊接面上壓接件的穿通區沒有裝置。

11、高器件之間無短器件，高度大於5mm的器件之間10mm範圍內無貼片器件和短小插接器件。

12. Polar 設備有極性絲印標誌。 同類型的極化插件元件的X和Y方向是相同的。

13. All devices are clearly marked, no P*, REF, etc. are not clearly marked.

14. 包含SMD器件的表面有3個定位光標，呈“L”形放置。 定位光標中心與板邊距離大於240密耳。

15.如果需要做登板加工，考慮layout，方便登板和PCB加工組裝。

16、切邊（異邊）應採用銑槽、沖壓孔補齊。 印章孔是一個非金屬化的空洞，通常直徑為 40 密耳，距邊緣 16 密耳。

17. The test points used for debugging have been added in the schematic diagram, and they are placed appropriately in the layout.

二、佈局的熱設計要求

1. Heating components and exposed components of the casing are not in close proximity to wires and heat-sensitive components, and other components should also be properly kept away.

2. The placement of the radiator takes into account the convection problem, and there is no interference of high components in the projection area of ​​the radiator, and the range is marked on the mounting surface with silk screen.

3、佈局考慮到了合理、流暢的散熱通道。

4、電解電容應與高熱器件適當隔離。

5、考慮大功率器件和扣板下器件的散熱。

三、layout的信號完整性要求

1. The start-end matching is close to the sending device, and the end matching is close to the receiving device.

2. Place decoupling capacitors close to related devices

3. Place crystals, crystal oscillators and clock drive chips close to related devices.

4、高速和低速，數字和模擬按模塊分開排列。

5、根據分析仿真結果或已有經驗確定總線拓撲結構，確保滿足系統要求。

6. If it is to modify the board design, simulate the signal integrity problem reflected in the test report and give a solution.

7. The layout of the synchronous clock bus system meets the timing requirements.

四、EMC要求

1. Inductive devices that are prone to magnetic field coupling, such as inductors, relays, and transformers, should not be placed close to each other. When there are multiple inductance coils, the direction is vertical and they are not coupled.

2、為避免單板焊接面上的器件與相鄰單板之間產生電磁干擾，單板焊接面上不應放置敏感器件和強輻射器件。

3. The interface components are placed close to the edge of the board, and appropriate EMC protection measures have been taken (such as shielding shells, hollowing out of the power supply ground, etc.) to improve the EMC capability of the design.

4、保護電路靠近接口電路放置，遵循先保護後濾波的原則。

5. 屏蔽體和屏蔽殼到屏蔽體和屏蔽罩殼的距離對於發射功率大或特別敏感的設備（如晶振、晶體等）在500密耳以上。

6. A 0.1uF capacitor is placed near the reset line of the reset switch to keep the reset device and reset signal away from other strong devices and signals.

Five, layer setting and power supply and ground division requirements

1、當兩個信號層直接相鄰時，必須定義垂直佈線規則。

2、主電源層盡量與其對應的地層相鄰，電源層滿足20H規則。

3. Each wiring layer has a complete reference plane.

4、多層板層壓，芯材（CORE）對稱，防止因銅皮密度分佈不均和介質厚度不對稱而引起翹曲。

5、板厚不得超過4.5mm。 對於厚度大於2.5mm（背板大於3mm）的，技術人員應該已經確認PCB加工、組裝、設備沒有問題，PC卡板厚度為1.6mm。

6、當過孔的粗徑比大於10:1時，由PCB廠商確認。

7. The power and ground of the optical module are separated from other power and ground to reduce interference.

8、關鍵部件的電源和地處理符合要求。

9、需要阻抗控制時，層數設置參數滿足要求。

Six, power module requirements

1. The layout of the power supply part ensures that the input and output lines are smooth and do not cross.

2. 單板給子板供電時，將相應的濾波電路放置在靠近單板電源插座和子板電源入口處。

七、其他要求

1、佈局考慮到佈線的整體流暢性，主要數據流向合理。

2、根據佈局結果調整排除、FPGA、EPLD、總線驅動等器件的管腳分配，優化佈局。

3. 佈局考慮到在密集佈線處適當增加空間，避免無法走線的情況。

4、如採用特殊材料、特殊器件（如0.5mmBGA等）、特殊工藝，已充分考慮交貨期和可加工性，並經PCB廠家和工藝人員確認。

5. 扣件連接器的針腳對應關係已經確定，防止扣件連接器的方向和方向顛倒。

6. If there are ICT test requirements, consider the feasibility of adding ICT test points during layout, so as to avoid difficulty in adding test points during the wiring phase.

7. When a high-speed optical module is included, the layout of the optical port transceiver circuit is prioritized.

8. 佈局完成後，已提供1：1裝配圖供項目人員對照器件實體檢查器件封裝選擇是否正確。

9、開窗時，內平面已考慮回縮，並設置了合適的佈線禁止區域。