1. Spacing between traces
In terms of the manufacturing capabilities of mainstream PCB manufacturers, the minimum spacing between traces should not be less than 4 mils. This minimum trace distance applies both between lines and between lines and pads. From a production perspective, larger distances are preferable whenever possible; a common practice is to use 10 mils.
2. Pad size and pad width
Regarding the manufacturing capabilities of mainstream PCB manufacturers, for mechanically drilled pads, the minimum aperture should not be less than 0.2 mm. For laser-drilled pads, the minimum aperture should not be less than 4 mils. Aperture tolerances may slightly vary depending on the substrate, generally kept within 0.05 mm. The minimum pad width should not be less than 0.2 mm.
3. Spacing between pads
According to the manufacturing capabilities of mainstream PCB manufacturers, the spacing between pads should not be less than 0.2 mm.
4. Clearance between copper features and board edge
The recommended distance between the charged copper skin and the edge of the PCB board should be at least 0.3mm. These spacing rules should be defined on the Design-Rules-Board outline page.
For large areas of copper, it is advisable to retract them from the board edge, typically set to 20 mils. In the PCB design and manufacturing industry, this practice is common due to mechanical considerations of the final circuit board or to prevent issues like curling or electrical short-circuiting caused by exposed copper on the board edge. Instead of extending copper to the board edge, engineers often shrink the copper block inward by 20 mils.
Various methods can address this copper shrinkage. For instance, one approach involves drawing a keepout layer along the board edge and setting a specific distance between the copper pour and the keepout area. Here’s a straightforward method to establish different safety distances for copper pours: set a 10 mil safety distance for the entire board and a 20 mil distance for the copper pour, achieving a 20 mil inward shrinkage from the board edge and eliminating any unwanted copper in device areas.
Non-electrically related safety clearances include:
1. **Character width, height, and spacing:**
During processing, text features cannot be altered. Characters with a D-CODE less than 0.22mm (8.66 mils) in width are thickened to 0.22mm. Character line width (L) is set to 0.22mm, entire character width (W) to 1.0mm, entire character height (H) to 1.2mm, and character spacing (D) to 0.2mm. Text below this standard may result in blurred processing and printing.
2. **Spacing between vias:**
Preferably, the distance between vias (hole edge to hole edge) should exceed 8 mils.
3. **Distance from silk screen to pad:**
Ensure the silk screen does not cover the pad to avoid issues during tinning and component mounting. A minimum space of 8 mils is typically required by board factories; in constrained PCB areas, a 4 mil pitch may be marginally acceptable. If silk screen inadvertently covers pads during design, the board factory will remove the excess silk screen during manufacturing to ensure proper tinning of the pad.
4. **Mechanical 3D height and horizontal spacing:**
When placing components on the PCB, consider potential conflicts with other mechanical structures in both horizontal and vertical dimensions. Adequate spacing must be reserved to prevent spatial conflicts between components, the PCB product, and its enclosure.
Each of these guidelines ensures that PCB designs meet manufacturing standards and minimize potential issues during production and assembly.
In terms of the manufacturing capabilities of mainstream PCB manufacturers, the minimum spacing between traces should not be less than 4 mils. This minimum trace distance applies both between lines and between lines and pads. From a production perspective, larger distances are preferable whenever possible; a common practice is to use 10 mils.
2. Pad size and pad width
Regarding the manufacturing capabilities of mainstream PCB manufacturers, for mechanically drilled pads, the minimum aperture should not be less than 0.2 mm. For laser-drilled pads, the minimum aperture should not be less than 4 mils. Aperture tolerances may slightly vary depending on the substrate, generally kept within 0.05 mm. The minimum pad width should not be less than 0.2 mm.
3. Spacing between pads
According to the manufacturing capabilities of mainstream PCB manufacturers, the spacing between pads should not be less than 0.2 mm.
4. Clearance between copper features and board edge
The recommended distance between the charged copper skin and the edge of the PCB board should be at least 0.3mm. These spacing rules should be defined on the Design-Rules-Board outline page.
For large areas of copper, it is advisable to retract them from the board edge, typically set to 20 mils. In the PCB design and manufacturing industry, this practice is common due to mechanical considerations of the final circuit board or to prevent issues like curling or electrical short-circuiting caused by exposed copper on the board edge. Instead of extending copper to the board edge, engineers often shrink the copper block inward by 20 mils.
Various methods can address this copper shrinkage. For instance, one approach involves drawing a keepout layer along the board edge and setting a specific distance between the copper pour and the keepout area. Here’s a straightforward method to establish different safety distances for copper pours: set a 10 mil safety distance for the entire board and a 20 mil distance for the copper pour, achieving a 20 mil inward shrinkage from the board edge and eliminating any unwanted copper in device areas.
Non-electrically related safety clearances include:
1. **Character width, height, and spacing:**
During processing, text features cannot be altered. Characters with a D-CODE less than 0.22mm (8.66 mils) in width are thickened to 0.22mm. Character line width (L) is set to 0.22mm, entire character width (W) to 1.0mm, entire character height (H) to 1.2mm, and character spacing (D) to 0.2mm. Text below this standard may result in blurred processing and printing.
2. **Spacing between vias:**
Preferably, the distance between vias (hole edge to hole edge) should exceed 8 mils.
3. **Distance from silk screen to pad:**
Ensure the silk screen does not cover the pad to avoid issues during tinning and component mounting. A minimum space of 8 mils is typically required by board factories; in constrained PCB areas, a 4 mil pitch may be marginally acceptable. If silk screen inadvertently covers pads during design, the board factory will remove the excess silk screen during manufacturing to ensure proper tinning of the pad.
4. **Mechanical 3D height and horizontal spacing:**
When placing components on the PCB, consider potential conflicts with other mechanical structures in both horizontal and vertical dimensions. Adequate spacing must be reserved to prevent spatial conflicts between components, the PCB product, and its enclosure.
Each of these guidelines ensures that PCB designs meet manufacturing standards and minimize potential issues during production and assembly.
