What is silkscreen in PCB?

A silkscreen in a PCB (Printed Circuit Board) is the layer of printed text, symbols and markings placed on the surface of the board to help identify electronic components and assembly points. It usually includes part labels, polarity indicators, pin numbers, company logos, warning symbols and test points. The silkscreen layer is commonly printed in white ink, though other colors may also be used depending on the PCB design and manufacturing process.

Silkscreen plays an important role in PCB assembly, testing, troubleshooting, and maintenance. It helps engineers and technicians place components accurately and quickly identify connections during repairs or inspections. Clear and properly designed silkscreen markings improve readability, reduce assembly errors and make the PCB easier to understand in complex electronic systems.

What Information Does a PCB Silkscreen Convey?

A PCB silkscreen is used to display the following information on a printed circuit board:

  • Electronic symbols
  • Pin numbers
  • Manufacturing details, including version numbers, manufacturer’s name, and so on
  • Switch settings
  • Polarity of parts
  • Reference designators
  • Test points

What Factors should be Considered for PCB Silkscreen Layout?

Although PCB silkscreen printing is an automated process, the following are a few factors to be addressed during the process.  

  • Font Type: Earlier, only a few standard fonts were allowed by CAD software, but now various fonts are used for silkscreen printing. The silkscreen contains important information on which engineers rely. Ensure to choose a font that is clearly readable by everyone.
  • Font Color: PCB silkscreen printing is done in different colors such as white, yellow, red, blue, and so on. Choose a silkscreen color that clearly gets highlighted on your printed circuit boards. For instance, if a PCB is green, white silkscreen printing can be a good option.
  • Designation: The location of the components and connections should be printed as close as possible to avoid any miscommunication. If the component density is high, silkscreen could be printed inside the elements with precise arrows and directions.
  • Reading Directions: The reading directions should be clear and simple, starting from left to right and bottom to top. This will make the circuit board more comprehensive for the engineers.

What Are the Common PCB Silk Screen Printing Methods?

There are three main methods used for PCBA silkscreen printing. They are as follows:

  1. Manual Screen Printing: As the name suggests, manual silk screen printing is done by hand. The task is performed with the help of a stencil comprising traces and texts made up of nylon. The non-conductive ink is evenly spread on the upper PCB layer through the stencil. After lamination, the ink is dried in a baking oven. The Manual screen printing method is the most cost-effective and simple. It is specially used for PCBs whose registration tolerance is 0.005.
  2. Direct Legend Printing: This is one of the most expensive and accurate methods of printing silkscreen. Direct legend printing, or DLP, is done using inkjet projectors and acrylic ink. The ink is applied on a printed circuit board using CAD software. This process can be used for PCBs that do not contain a silver finish because acrylic ink is not suitable for the same.
  3. Liquid Photo Imaging of Silkscreen: This printing method is used on a PCB with a width of fewer than four millimeters. Firstly, the lamination is done using light-sensitive epoxy. Once the silkscreen image is printed, it is then exposed to UV light.

PCB Silk Screen Printing Process

PCB silkscreen printing is the process of adding text, symbols, component labels, logos, and markings onto the surface of a printed circuit board (PCB). This layer helps manufacturers, engineers, and technicians easily identify electronic components, polarity marks, test points, and assembly instructions during PCB assembly and maintenance. The silkscreen is usually printed using white ink, although other colors may also be used depending on the PCB design requirements.

The PCB silkscreen printing process is typically done after the solder mask layer is applied. It can be created using methods such as screen printing, liquid photo imaging, or direct legend printing. High-quality silkscreen printing improves PCB readability, reduces assembly errors, and supports faster troubleshooting and repair. This process is widely used in consumer electronics, industrial equipment, automotive electronics, and medical devices.

PCB silkscreen prints help new operators to make accurate connections. However, it is crucial to get the right information printed through silkscreen. To achieve this, you must partner with a trusted and reliable manufacturer like Suntronic Inc. The company provides excellent PCB assembly services from new product introduction (NPI) to silkscreen printing and PCB plating. You can get in touch with the company today to learn more about their PCB assembly services and PCB silkscreen printing capabilities.