How to Judge the Acceptance of PCB Quality
Which Color Circuit Board Sells the Most Expensive
Method to Solve the Noise Interference of Power Supply on High-frequency PCB Board
Disassembly Skills of Chip Components on PCB
What Factors Should Be Considered in the Selection of High-frequency PCB CCL
How to Place Special Components during PCB Layout
What Are the Functions of Capacitors in Circuits?
Testing Techniques for Common Electronics Components
What to do if There is a Short Circuit on the PCB
Desoldering Principles and knowhow during PCBA Processing
Black Oxidation of the Inner Layer of the Multilayer PCB
How to Ensure the High-performance Design of PCB
What Is the Printing Process of SMT Solder Paste?
PCB without fiducial mark, Is There Any Way to do SMT for It
What Are the Benefits of Reserving Break-up Tab for PCB Production
How Does SMT Affect PCB Production Time and Speed It Up
Classification of PCBs from three aspects
Common Problems and Solutions for Dry Film pasting during PCB Manufacturing process
Several Elements to Inspect after PCB Design
What is a halogen-free circuit board?
What Do Capacitive Coupling and Decoupling Mean?
What Are the Differences Between PCB Paste Mask and Solder Mask?
How PCBA Is Packaged and Shipped
How long can PCBA finished products be stored?
What Are the Differences and Relations Between PCB, PCBA, and SMT?
PCB Baking Specifications
PCB "Solder Mask Tenting" and "Solder Mask Opening"
Five reasons for PCB deformation and six solutions
Importance of first article inspection of PCBA board
Temperature zone standard for SMT reflow soldering
Small and medium volume PCB manufacturers in China
The main reason for PCBA cleaning
For power filter, the more capacitors, the better?
What does PCBA programming mean?
Content of PCB incoming testing
What conditions must be met for PCB circuit board soldering?
What is Blind via and Buried via
PCBA Manufacturers Temperature and Humidity Sensitive Components Management
Why choose Shenzhen SMT processing factory?
How long does it take to calculate the quotation for PCBA manufacturing?
Introduction of PCB design clearance requirements
Explanation of BOM, DIP, SMT, SMD
Introduction of the process of PCBA prototype
How to prevent pseudo soldering or cold soldering defects in PCBA manufacturing?
Factors that affect the Price of FPCB
What information is required for SMT processing at PCBA factory?
Skills of using 0ohm resistor in PCB design
How to select a PCBA manufacturer
SMT processing solder joint quality inspection
Characteristics difference between immersion gold PCB and gold plating PCB
Common malfunctions of Circuit Board Caused by Moisture
A Few Rules about PCB Panelization
Compare of multi-layer PCB with single/double layer PCB
Why do we need to introduce so many subdivided GND
Difference between immersion gold boards and gold plating boards
Aluminum PCB structure
Classification of different GND in circuit
Why PCB baking is necessary during manufacturing process
The handle and precautions of OSP board in SMT process
How to choose capacitors for filter decoupling
How to choose filter capacitor for switching power supply
5 database need for SMT process
Function of three-terminal capacitor
Introduction of PCB OSP surface treatment
Method of inspecting the quality of SMT by step
How to find the short point between VCC and GND
Difference between 850nm and 940nm infrared LED
Component layout of PCB SMT DFM
Pad shape influence on the strength and reliability of the soldering joints
The difference between high temperature solder paste and low temperature solder paste
Introduction to manual welding processing
Manual visual inspection in PCBA processing
Characteristics of the conformal coating process
Difference between hardware engineers and software engineers
PCBA processing operation rules
China PCB upstream materials has continued to soar
Difference between serial buses and parallel buses
The key points of quality control in PCBA processing
Common causes of solder beading during SMT process
Analysis of the advantages and disadvantages of HASL PCB surface
Requirements for layout of components during SMT assembly
Selection of electronic components and CCL for PCBA
Performance and appearance quality inspection of components.
Quality and Reliability of SMT Chip Processing and Production
Coupling and decoupling function of capacitor
Two methods to connect digital ground and analog ground
Common sense in SMT process

Introduction of PCB design clearance requirements

We will encounter various safety spacing issues in ordinary PCB design, such as the clearance between vias and pads, and the clearance between traces and traces, which are all things we should consider.

In PCB design, we divide these spacing into two categories:
Electrical safety clearance
Non-electrical safety clearance

I. PCB design-Electrical safety clearance

1. PCB design spacing between lines
This clearance needs to consider production capacity, and it is recommended that the clearance between the traces is not less than 4mil. The minimum conductor spacing is also the conductor-to-conductor and conductor-to-pad spacing. So, from the perspective of production, if conditions permit, the bigger, the better. Generally, the conventional 10mil is relatively common.

2. Via size and pad width
According to the PCB manufacturer, if the Via is mechanically drilled, the minimum diameter should not be less than 0.2mm. If using laser drilling, it is recommended that the minimum diameter not less than 4mil. The Via tolerance is slightly different depending on the board material, generally can be controlled within 0.05mm, and the minimum pad width must not be small than 0.2mm.

3. The spacing between the pad and the pad
According to the processing capability of the PCB manufacturer, it is recommended that the clearance between the pads is not less than 0.2mm.

4. The clearance between the copper and the edge of board
The clearance between the copper and the PCB board edge is preferably not less than 0.3mm. If it is a large area of copper plane, there is usually a pullback clearance between the copper and the board edge, generally set to 20mil.

Under normal circumstances, due to considerations of the finished circuit board machinery, or to avoid copper foil curling or electrical circuit-short that may be caused by the exposed copper plane on the edge of the board, engineers often set a 20mil pullback clearance between the large-area copper and the edge of the board, will not spread the copper to the edge of the board. There are several ways to deal with the pullback of the copper plane. For example, draw a keep-out layer on the edge of the board, and then set a distance between the large-area copper and the keep-out layer.

II. PCB design non-electrical safety clearance

1. Silk screen width and height and spacing
Regarding the PCB design silkscreen, we generally use conventional values such as 5/30mil or 6/36mil and so on. Because when the legend is too small, the finished PCB silkscreen will be blurred.

2. The distance from the silk screen to the pad
The silk screen is not allowed to printed on the pad, because if does, the silk screen on soldering PAD will affect the component mounting.
Generally, the board factory requires a space of 8mil to be reserved. If the area of some PCB boards is really tight, the 4mil pitch is barely acceptable. Then, if the silk screen accidentally covers the pad during design, the board factory will automatically eliminate the silk screen on the pad during DFM, to ensure that the pad can be wetted by solder during SMT process. Thus, we need to pay attention.

3. 3D height and horizontal spacing on the mechanical structure
When mounting the components on the PCB, consider whether there will be conflicts with other mechanical structures in the horizontal direction and the height of the shell. Therefore, when designing, it is necessary to fully consider the adaptability of the space structure between the components, and between the finished PCB and the product shell, and reserve a safety distance for each target object.