Something You Ought to Know About PCB Silkscreen Printing

The layer of printed text, symbols, marks, and images on a printed circuit board's (PCB) surface is referred to as PCB silkscreen. As part of the PCB manufacturing process, it printed specific ink or substance that resembles ink onto the PCB surface so that it offers information on component placement, assembly instructions, and identification.

In the following chapters, we will explain in more detail the advantages of silkscreen in PCB. At the same time, we will also explain the three methods of creating silkscreen and their corresponding advantages and disadvantages.

It prints the PCB silkscreen on top of the circuit layer and solder mask; it is also called the component side or top side. In particular, we can include a variety of information in the silk screen layer, including warning signs, assembly instructions, business or brand logos, component names, indications, etc.

Following the completion of the solder mask and circuit layers, we carry PCB screen printing out in the latter stages of the production process. To generate the marks and information, we apply the screen printing ink to the PCB surface using a fine mesh screen or stencil. To provide good visibility against the PCB backdrop, contrasting colors such as we typically use black or white in screen printing inks.

· Pros of applying Silkscreen PCB printer

There are 7 main reasons why people choose silkscreen printing on PCB:

1. Component Identification

2. Assembly Guidance

3. Circuit Understanding

4. Branding and Logo Placement

5. Aesthetics

6. Compliance and Certification

7. Documentation and Reference

Take component identification as an example, it provided a visual guide for identifying JLCPCB components via silkscreen printing. We can make it function as a sign, name, or label for different components in real-world applications. When assembling, testing, or troubleshooting a system, assembly specialists and maintenance staff may discover and identify individual components much more rapidly with the use of these identification labels. Moreover, JLCPCB silkscreen printing may offer additional identifying markings or show the number of layers with multi-layer PCBS, which can aid with the proper stacking and arrangement of the layers during the manufacturing process.

· Techniques used in PCB manufacturing & its Pros and Cons

- Manual screen printing

On a silkscreen PCB, manual screen printing employs a screen printing technology to apply ink to a PCB while doing it by hand. To be specific, when the line width is over 7 mm and the line's registration tolerance is 5 mm, this procedure can be applied. You will need a nylon tracing stencil and PCB silkscreen minimum text size for this procedure. Using the stencil, we imprint the oil onto the plate. The PCB board will then need to be cooked in a curing oven and allowed to solidify.

Pros: Firstly, it is really cost-effectiveness for small-scale production. As for small-scale production, equipment, and setup costs are typically lower compared to using automated printing methods. Secondly, this method is versatile. Fabrics, paper, plastics, and PCB are just a few of the materials hands may print on. It is appropriate for a variety of applications since it can print on both curved and flat surfaces. Moreover, design modification options are flexible with manual screen printing. Small runs or one-off printing benefit from its ability to be changed and adjusted on the fly.

Cons: However, Manual screen printing on screen-printed circuit boards requires skilled operators who can accurately align the screen, apply consistent pressure, and ensure proper ink coverage. Therefore, it is a labor-intensive process. So for larger production volumes, automatic screen printing machines are often used to increase efficiency and accuracy. Also, more sophisticated printing techniques like LPI or DLP may reach higher levels of resolution and fine detail than manual screen printing. It works best on designs with more substantial components and simpler details.

- Liquid photo imaging (LPI)

We shall initially cover the laminate through the epoxy in liquid photo imaging. The liquid epoxy can image photos. Then, apply UV light exposure to transfer the silkscreen drawing to plates. They commonly used LPI for various purposes, including solder mask application and silkscreen printing.

Pros: Similar to the manual screen printing method, LPI offers versatility. LPI is suitable for a variety of applications in PCB manufacturing, including solder mask application and screen printing. It can be used to create protective layers, text, logos, and other markings on PCB surfaces. Also, complex design replication is made accurate and efficient with LPI. Consistency is ensured, and we removed manual corrections or alignment with the use of digital files and UV exposure. It is noticeable that different from the manual screen printing method, LPI allows for the creation of high-resolution patterns and designs on the PCB surface. It can produce fine features, intricate details, and precise registration between different layers of the PCB.

Cons: When compared to automated techniques, LPI might be a time-consuming procedure. Particularly for intricate designs or big PCB quantities, the exposure and development phases could take longer than expected. Moreover, the LPI process is relatively complex, including ink coating, exposure, and development. It requires careful control of variables such as exposure time, developer, and drying conditions. To achieve consistent results, a precise and controlled environment is required.

- Direct legend printing (DLP)

DLP is a digital printing method that utilizes a projector or light source to selectively cure a liquid resin layer by layer.

Pros: DLP offers high precision and resolution, allowing for the creation of intricate and detailed patterns on the PCB surface. It can create intricate patterns, intricate geometries, and accurate circuit traces. Also, when comparing DLP with traditional techniques, production time can be reduced. It allows for the simultaneous curing of numerous layers, which speeds up manufacturing cycles and prototyping. Moreover, DLP enables customization and flexibility in design. Digital files allow for quick prototype and design iterations due to their ease of modification and adjustment.

Cons: DLP systems can be expensive to acquire and maintain. Specialized tools, such as curing systems, resin ingredients, and DLP projectors or light sources, can need a large initial outlay of funds. Not only that, the material selection is relatively limited by using DLP. Resin-based materials, which could have distinct material qualities from traditional PCB substrates, are the main materials for which DLP is appropriate. There might be fewer alternatives available in terms of the variety of materials that can be used for DLP.

Conclusion

It's vital to consider your project's particular requirements when thinking about silkscreen printing for PCB production. It is important to examine factors including production volume, design complexity, desired print quality, and budgetary constraints. While keeping in mind its limits regarding resolution and registration precision, silkscreen printing is especially well-suited for applications where clear identification and labeling, customization, and visual aids are crucial.