If we would like to leave some useful information on the circuit board for better recognition in the following manufacturing and assembling procedure, then PCB silkscreen provides a best way to achieve. For example, circuit points, components, circuit symbols and other information. Sometimes, restricted by limited space, the key information or marks need to be considered first.
In this article, we focus on steps for how to make PCB silkscreen, start from designing, manufacturing and process. In addition, we also provide some factors that should be considered during PCB silkscreen design for better manufacturing.
What can we get to know from silkscreen?
In general, PCB silkscreen enables to reveal the following information.
- Component reference mark
- Polarity mark
- Pin mark
- Component boundaries
- Company logo
- Manufacturer’s mark
- Warning symbol
- Season number
- Version number
- Date code
How to make silkscreen?
1.PCB silkscreen design
Employing some PCB design software such as EDA to design the silkscreen layer, including all necessary markings, symbols and text needed to identify and assemble components on the PCB. Then export the format that your manufacturer requires.
2. PCB manufacturing
The PCB manufacturing process involves printing a layer of copper on a substrate, drilling holes for the components, and then etching away the excess copper to create the PCB, which can come in different shapes and patterns. The screen is printed on top of the copper layer using a specialized silkscreen process.
3. Perform PCB silkscreen
After the PCB is manufactured, the screen layer is printed through a silkscreen process, which involves creating a template for the silkscreen design. Create a stencil of the desired image by spreading photosensitive emulsion onto the grid.
4. Curing ink
After the silkscreen layer is applied, the ink must be cured to ensure it adheres properly to the PCB substrate, usually by exposing the PCB to heat or UV light for a specified period of time.
5. Check and test PCB
Finally step, inspect and test the PCB to make sure the silkscreen is properly applied. And the most important, some required markings and symbols are printed. That’s because errors and omissions in silkscreen can result in incorrect assembly or functionality.
You can see the picture below, which is a PCB 3D picture with silkscreen:
The following is the PCB 3D diagram with the silkscreen layer removed.
Some factors should be considered for PCB silkscreen design
Here are some considerations for PCB silkscreen design.
1. Component direction and polarity
The direction on the silkscreen marks the direction in which the component is soldered, usually represented by a dot, identifying pin 1 of the IC. For LEDs and diodes, it is “+” or “C”. Among them, C is the cathode , and A is the anode. If it is a capacitor, the semi-shaded circle indicates negative polarity, and “+” indicates positive polarity.
2. Direction overlap
Edit the text direction of component references, part types, etc., to ensure that they are all in one direction for easy recognition. Besides, you can also set top and bottom silkscreens.
Check for overlapping text before rotating text and adjusting component reference marks. As shown in the image below, the markers are not aligned and also overlapped. When assembling and troubleshooting, it is useless to take them as reference.
Therefore, if we encounter such an overlapping situation during PCB silkscreen design, we need to rotate and move the component reference indicator to the correct direction and position through the corresponding component.
Check whether a component reference marks placed on a PCB pad overlaps the pad. The first mark circled in the figure below overlaps with the pad, and there is no way to use it as a reference when we are troubleshooting the circuit board. Therefore, the marker needs to be moved to the empty position of the corresponding component.
Check the marks on the vias. Mark the second component in the figure below. Since tented vias can not be printed, so when we use tented vias that cover the vias with solder mask, we can not use it as a test point. It’s better to move it next to the component.
Check that the reference marks are placed so that they are below the object after the component is welded. If there is a marker below the component as shown below, move the blank space next to the component.
3. Additional mark
The extra mark added can better show the direction of the component. As shown in the figure below, in addition to the original mark direction of the component, we can also add marks in the shape of triangles, circles, etc., which can show the direction of the I/O component.
Place a polarity mark outside the component object mark, such as the positive polarity mark shown in the figure below. Generally, components with polarity such as electrolytic capacitors, diodes, and LEDs need to be marked with this.
Measurement marks for the number of pins and lines on the IC can be added to the silkscreen as follows:
4. Silkscreen process
Choosing the appropriate silkscreen process is of importance. The silkscreen method affects the design parameters such as the size, clearance and position of different component pads, traces, vias.
5. Appropriate silkscreen fonts
By choosing an appropriate font , such as the size, height, color, and font enables to provide better views when we would like to gain information from the silkscreen. The most common sizes are 35 mil height and 5 mil line width, and 25 mil height and 5 mil line width.
Conclusion
PCB silkscreen, as an essential procedure of PCB manufacturing, can not be neglected. The above content something about how to make PCB silkscreen provides suggestions for you.
Founded in 2005, IBE Electronics becomes one of the experienced PCB and PCB assembly manufacturers in China. Currently, we have 4 factories in China, Vietnam and the USA, which is capable of finishing PCB assembly production with high-quality.
PCB Silkscreen is a layer of characters, labels, and symbols that is printed onto the surface of the board. Typically placed on the top and bottom layers of the circuit board, it provides visual information about components, their location, part number designations, part numbers, logos, and other relevant details.
- Component Identification
- Assembly Guidance
- Troubleshooting and Repair
- Manufacturing and Assembly Documentation
- Aesthetics and Branding
- PCB Design
- Gerber File Generation
- Stencil Creation
- PCB Manufacturing
- Silkscreen Printing
- Curing/Drying
- Inspection and Quality Control
