The silkscreen on the PCB refers to a mark on PCB board. Usually used in white and black color, some times with other colors too, such as brown or red. It is best to use a color that contrasts strongly with the substrate solder mask and looks sharper. Such as green solder mask with white silkscreen, white solder mask with black silkscreen. Silkscreen is like a map on the PCB, can reflect the position and size of each component, which is the most basic and important function. On the silkscreen of a PCB you may print all sorts of information like the component reference designators, company logos, manufacturer marks, warning symbols, part numbers, version numbers, date code, etc.
The silkscreen on the circuit board looks simple, but there are a lot of important information elements, play an important role in the whole PCB producing process. The perfect design will definitely include the perfect silkscreen, because the silkscreen contains the position, package(foot print), polarity of the component, it will also help IQC to compare components and pads, help engineers detect the electronic printed circuit board and so on.
As an OEM factory, we have a wide range of design types and work with engineers in many countries. There are subtle differences in the PCBs of different designers from different countries. Today, I will introduce some of the problems about silkscreen we met before and how to improve them.
Silkscreen shows the components packages and polarity
We have encountered a very complicated circuit board with many components and many silkscreens overlapping, which makes it difficult to distinguish the position and package(foot print) of components. At this time, pick and place file is needed to confirm the specific components of the position. When we finish PCB making and before SMT work, our IQC will first compare all items of BOM with the real PCB. They mainly check if every component fit the pads. Each pads and mounting hole should always has silk screen, it shows the package of each component.
In the right case, put component on the silkscreen, it can cover the silkscreen, this shows component and the board are compatible.If the component is obviously too large or too small, indicating that the designer’s design of the circuit board or selected component has a problem. At this time, it is necessary to confirm with the customer, solve the problem in advance, so as not to complete the assembly, and then discover the problem after sending it to the customer.
In addition shows the component package(foot print), silkscreen can reflect the polarity of the component. This point is very important. Because some components are polar, when soldering these polar components to the PCB board, we must pay attention to the direction. If the direction is wrong, PCBA will not work, and even components and PCB boards will burn out and cause damaged. Experienced designers will make special markings on polar components, one corner, or two lines to distinguish the difference. Follow the correct direction of components soldering, the original circuit principle can be realized, and the PCBA can work normally to achieve the designed function.
Silkscreen can help designers label design versions
Silkscreen can help designers label design versions, such as V1.1, V1.2, V1.3… When they receive the product, they can clearly know which version it is. After many batches of production and many years usages, they can clearly distinguish each batch, with or without a modified. On the other hand, the PCB factory sometimes marks the batch with a small silkscreen at the corner of the PCB board. The details is used to record dates or some other info, when problems occur, technician trace back to the root cause problem by that silk print.
Silkscreen will help engineers do test and troubleshoot.
Silk screen will help engineers do test and troubleshoot. Many silk screen on PCB board mark the test point or the test program location. When a completed PCBA is not working properly, the engineer will usually check the components one by one. The silkscreen will make the position of each component clearly, so that the inspection work is not missed.
The PCB board will mark the words such as high voltage and other reminders, sometimes will have the brand and model. In some cases, in order to reflect the level of the PCB and meet the standards, there will be UL silkscreen and 94V0 silk screen too.
Silkscreen helps the assembly(SMT) work
Silkscreen helps the assembly(SMT) work. Get a PCB board, according to silkscreen we can understand it is a single-sided mount or double-sided mount PCB. (If the PCB with silk print on both side, it means it is a double side mount PCB). The silkscreen help us to know components are should be soldered to the top layer or the bottom layer of the PCB. Some silkscreens are like a top view of a component, where should place some pins, and the holes of the connectors are very obvious, which can help the welder to work accurately.
Solder mask and silkscreen are the end of the circuit boards production, just like putting a beautiful coat on the printed circuit board. Especially for silkscreen printing, high-quality clear silkscreen reflects the quality of the PCB board to some extent. Therefore, when we produce the circuit board, we will use high-grade ink, clean screen frame, strictly control the strength of the oil scraping, control the baking temperature and so on. In this way, the silkscreen can be clear and high performance.
In order to design a good silkscreen you need to:
- Edit the orientation of text for component reference designator, part type, etc so that all these have the same orientation.
- Check for overlapping texts a common problem before rotating the text and adjusting the component reference designator marks.
- Check for component reference designator marks that were put over circuit pads overlapping with the pads.
- Check for marks over via holes.
- Check if there are any reference marks placed.
- Additional Marks
- Place polarity marks like the positive mark outside of the component object marks.
- Add measurement marks of the number of pins and lines on a microchips (ICs) on the silkscreen.
Engineers in our company solve many gerbers from various countries every day. No silk print layers, silkscreen are printed on via holes or through vias, the silkscreen is not clear etc.. Our engineers will provide a EQ and solution ways to customers. By confirming and modifying, we can solve problems at the beginning and bring convenience to the next step-PCB production and assembly work.
As a professional PCBA Manufacturer, we could supply one-stop service, including PCB board making, PCB Reverse Engineering, components sourcing, SMT assembly work, Program+Test, housing making, housing assembly…
We aslo have ERP system to manage every project from production file, quotation, purchase, production, delivery until service after it. Date will be found quickly and precise no matter when client wants to begin project.
If you have related projects, welcome to inquiry us to get free quotation.