Taiwan Province is an important electronic information and communication city. pcb stackup calculator I believe that most people are familiar with the printed circuit board (PCB), but I wonder why you have ever wondered why the printed circuit board is usually green? Even many engineers are curious about this question. What causes the printed circuit board to be green? This article reveals the answer for three reasons.
Printed circuit board in fact is not the problem has been green, the only green part is the resin shell, also known as the solder stop layer or solder stop, is a hardened resin with color pigments, to screen printing applied to the circuit board, the solder stop layer is designed to protect the electronic circuit below from the impact of environmental moisture and dust, and control the flow of molten solder.
The core of a typical FR-4 board is actually a dull yellow, 1 oz vs 2 oz but welding masks can come in multiple colors, such as blue, red, yellow, black, and white, and even more exotic colors, such as orange, pink, purple, matte, or mixed palettes, so the question is "why green at the end?" ? "
1, green can alleviate eye fatigue
Early technical limitations, quality detection mainly rely on workers to check the circuit board with the naked eye, squinting all day to look at the small circuit board is very tiring work, neuroscientists and psychologists agree that green light wavelength has a relaxing effect on the body, can reduce fatigue.
Experts found that the human eye sensor cells or cones are the most sensitive to green light, so the circuit line, pad, screen printing and the contrast between the blank area is greater, as long as the circuit board is observed from the outside, you can easily identify the outer defects, and compare the green board image below with other colors, the higher the contrast, the easier it is to find errors.
Of course, PCB manufacturers today use flypin testing and automated Optical inspection (AOI) quality inspection of boards to find errors very effectively, but there is another very important technical reason why most printed boards are still green.
2, green solder resistance layer physical system performance is superior
The traditional use of green pigments can be more focused on the use of solder resistance oil research and development, the actual use of chemical pigments will affect the performance of the resin, relatively practical, no one cares about the pink circuit board, so compared with other aesthetically oriented colors, green solder resistance layer has superior performance.
Notably, commercial green welding masks are the only available colors for the production of 0.1 mm (4 million) welding masks, followed by 0.12 mm red, yellow, and blue, followed by black and white, usually only 0.15 mm, solder DAMS are critical for IC and detail distance components, Because they are valuable in preventing Bridges from forming.
You know what? Most green welding oils get their green color from chlorine, which, along with bromine, is a halogen on PCBS substrates that can have serious health and environmental effects if not disposed of properly and is therefore critical to providing halogen-free welding oils and substrates that can be changed to another color.
3, Reduce costs
Welding masks are often used for screen printing technology applications, each color requires a screen printing workstation, and the design of many different orders is combined to enable manufacturers to make full use of PCB space and reduce waste, but there are many processes that require the same treatment for the entire panel, such as surface treatment and perforation plating. So all boards on each panel must have the same requirements.
Adding more and more enterprise-specific social features, manufacturers are more likely to end up with inadequate design, filling the panel at once, and factors such as solder resistance layer color or board thickness can be added to the picture, but it will increase the cost of the product, even if manufacturers are willing to undertake some specific environmental requirements, and eventually have to pay the cost of the entire panel, so restrict and certain color and feature combinations. Manufacturers can reduce production costs.