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Know common PCB colors and uses all here
1. What does the PCB color mean? PCB color generally refers to the oil color on the board that is most intuitively seen when you get a PCB board. The color of the PCB surface is the color of the solder resis t . PCB board dyeing pigment is a kind of hardened resin, the main resin is colorless and nearly transparent, and green is the color matching of toner just like other colors. We print the colors onto the PCB by screen printing . PCB colors can be green, black, blue, yellow, purple, red and brown. There are also some manufacturers who have ingeniously developed PCBs in various colors such as white and pink . 2. Is there any difference between different PCB colors? 1 ) . Green PCB Green PCB is the most popular color . Therefore, many people have always misunderstood that the PCB is green or mostly green. Green increases the clarity of the PCB , because the green PCB will have a sharp contrast with the white text, thereby enhancing readability . Additionally, the green PCB surface finish reflects less light, helping to reduce glare. Green PCB 2 ) . White PCB White PCBs look clean and crisp in various environments and are becoming more and more popular. However , white PCBs are still not the first choice because white PCBs are easy to hide traces . But the white PCB looks especially contrasty against the black silkscreen. White PCB 3 ) . Yellow PCB In the past, yellow PCBs were often used, but it is not so practical now. Yellow PCB can quickly meet different needs such as style, cleanliness and visibility. Yellow PCBs have one obvious disadvantage: poor contrast with traces and silkscreen . 4 ) . Blue PCB Blue PCBs are considered as the thick boards for labels as it provides a significant screen printing contrast . This PCB color is not as eye-catching as green PCB, black PCB or white PCB, but blue PCB is the preferred PCB color because it provides excellent aesthetic options. A blue PCB is better used for LCD because blue PCBs do not produce sharp contrasting edges and bright background colors. Blue PCB 5 ) . Red PCB Due to some advantages of red PCB , many PCB manufacturers are keen to adopt red. The red PCB provides excellent visibility and clearly defines the contrast of traces , planes and blank areas . The silk screen looks very beautiful against the red PCB. Red PCB 6 ) . Black PCB Black PCBs are as popular as white PCBs. These two PCB colors create low contrast, allowing easy marking of important components . However, the main disadvantage of black and white PCBs is that specific details may spotlight and have small shadows . This shadow makes tracking difficult. Therefore, it is not advisable to use black PCBs in various high-temperature applications because black PCBs may discolor the silkscreen . Moreover, the black PCB board is a mixture of cobalt and carbon, which may have poor conductivity . Black PCB 3. Which process is used to complete the PCB color? Different colors do not affect how the PCB is manufactured . Copper is still placed on one or both sides, and the PCB becomes smooth as copper is added or removed. The copper layer on the PCB is very thin, which is why the green color stands out so much. The thin copper layer is eventually covered during soldering to keep it from oxidizing, which is how the solder mask is made. It's also standard in green in many cases. In other colors the copper won't show through clearly so it can be hard to see where the traces are. After the traces are drawn, place the components in place. These need to be soldered in place according to the board diagram. Finally, with the components in place, the board is tested. If they work, they go into production. Most printed circuit boards need to be designed by engineers and prototypes need to be made before going into production. PCB 4. Why are most PCBs green now? This is mainly because the green solder mask process is the most mature and simple, and the green PCB board is also more environmentally friendly. In addition to green, the color of the circuit board also has white, yellow, red, blue, matte, and even chrysanthemum, purple, black, bright green and so on. White exists because we have to use it to make lamps. The use of other pcb colors is mainly to distinguish different product samples. In the whole stage of the company, from research and development to product landing, it depends on the various uses of PCB. The color of the experimental pcb board may be purple, the color of the button pcb is red, and the color of the pcb inside the computer is black. Several reasons for choosing green PCB are listed below: 1 ) . Glass epoxy resin material Glass epoxy is a material used in the manufacture of circuit board solder mask . This material used to be green and became the standard color for all fitters in the industry to use the same glass epoxy. Later glass epoxies of some other colors were introduced as well, but assemblers always considered green. 2 ) . Contrast between green and white printed text Assemblers often find it easy and time-saving to scan green boards because they are used to and very familiar with the color. They say it takes a lot of time to scan some boards of different colors. Another reason is that green places less strain on the eyes when scanning compared to other colors. Green is used because it also contrasts with the text printed in white on the board layout. 3 ) . It is widely used in the military How military standards goes has a big impact on green circuit board. Many people believe that green is very effective in circuit boards for military purposes. The military requires suppliers to provide green circuit boards, and these suppliers also supply other customers. These boards ended up as leftovers from military suppliers. So not only are assemblers, line workers or other customers considering green, the military is also accepting green for circuit boards. 4 ) . Exposure rate of solder mask The board requires a higher soldering rate, and there are other colors, but they don't provide a higher solder mask for circuit board. Those with darker colors, such as blue, white, or brown, have high pigmentation, so they have a dark solder mask. Mainly white and black solder mask with high exposure. But green provides a dark shade for worker exposure and high tolerances in the design. 5 ) . M achine recognition is better to Green PCB Generally speaking, electronic products have to go through board making and assembly of components. There are several steps to making a circuit board in the yellow lighthouse. When the PCB color is green, the visual effect is better in the yellow light room . But that's not the main thing. When soldering, it must be checked by brushing tin on the solder paste, the pads and the AOI on the back. These processes require optical positioning and calibration, and the green PCB background color has a better recognition effect on the instrument. 6 ) . Green PCB will be more comfortable Part of the inspection process is observed by workers (but now most of them use flying probe inspection instead of manual work), staring at the board under strong light, the green pcb board is more friendly to the eyes . 7 ) . Green PCB can reduce production cost Due to the wide range of uses of green PCBs, green PCBs can be used in both production and procurement fields. In addition, in mass production, the same color paint can be used to reduce production line costs, so the purchase cost of green paint will be lower than other costs. Therefore, green is the most common resist, which has advantages in terms of manufacturing cost and lead time . 8 ) . Green PCB is relatively environmentally friendly. The waste board will not release toxic gas when it is recycled at high temperature. Other PCB colors, such as blue and black, are doped with cobalt and carbon respectively, since they are less conductive and have a risk of short circuits. In addition, like black lights, purple lights, blue lights, etc., the color of the circuit board is too dark, which will increase the difficulty of maintenance of the main board , and the process is not easy to control. PCB Taking the black board as an example, the black board is most likely to have problems in the production process and raw material ratio. A little carelessness will cause obvious color difference, resulting in a high PCB defective rate. The traces of the black circuit board is not easy to distinguish, which will increase the difficulty of later maintenance and debugging . Many PCB factories do not use black PCBs very much.
February 14,2023READ MORE
- YYfab'Circuits
How to choose proper solder paste during PCB assembly
Devil is in the detail, choosing solder paste may seem like a trivial matter, but actually solder paste can make or break the PCB assembly process. There are all kinds of solder pastes to choose from on the market, while it doesn't look like that much of difference based on the classification, not all solder pastes are created equal. Specialty solder pastes are generally more expensive, but often have additional benefits. Choosing the right solder paste will avoid many problems. Many factors influence solder paste selection, such as: wetting characteristics, void control, flux residue, alloy strength, alloy flexibility, and other performance metrics. Changes in these performance indicators will affect the selection of solder paste. For example: Quality can be maximized by choosing a slurry that performs best with the material, geometry and heating process used to manufacture the product. Throughputcan be maximized by selecting a solder product for optimal deposition and heating methods . Cost targets depend on quality and yield, and can be maximized by considering material, direct labor, inspection, rework, and scrap values. Here are some factors to consider when choosing the right solder paste. 1.Leaded or lead-free solder paste The biggest difference between l eaded and lead -free is toxic and non-toxic , and the other is the melting temperature . Lead-free solder paste has a higher melting point. Here you can choose according to the actual requirement. Regarding leaded and lead-free solder paste, there is a detailed summary in the previous article, you can click on the title to jump directly. Leaded solder (left) and lead-free solder (right) 2.Water-soluble or no-clean solder paste? Water-soluble solder pastes contain high-molecular compounds, such as polymers, which are not as effective as rosin/resin in preventing re-oxidation . After the board goes through the reflow stage, the water-soluble solder paste gives the board a cleaner look, with the flux residue burned off and easily washed off in a board washer. No-clean pastes function is the same as water-based pastes, but residues are left on the board . No-clean chemistries are typically rosin/resin based materials. The rosin/resin could forms an excellent oxide barrier and protects the "clean" surface from re-oxidation during reflow, where aesthetics can suffer. The specific ones can be selected according to actual requirements. 3.Melting point temperature of solder paste Shown as below picture, each alloy has a temperature at which it changes from solid to liquid , as shown in the diagram below . The phase transition from solid to liquid begins when the solidus is reached and ends when the liquidus is reached . Below the solidus line, the alloy is 100% in the solid state. Between the solidus and liquidus, a region known as the plastic range, some parts of the alloy are solid but mostly liquid. When the solidus and liquidus are equal, the alloy is called a eutectic alloy. Although wetting begins at the solidus temperature, optimal wetting is achieved at 15º C higher above the liquidus or higher peak temperatures. If the solder joint needs to maintain physical integrity during a subsequent operation (such as a second reflow process), the peak temperature of the subsequent operation needs to be below the solidus temperature of the alloy. Melting point temperature of solder paste 4.Alloy composition Generally , you can choose Sn63 or Pb37 solderalloy composition , which can match the soldering requirements. For Ag or Pd plated products, you can choose Sn62 or Pb36 or Ag2 solder paste. For products without thermal shock , you can choose solder powders containing bismuth . Alloy Composition Solder Paste Selection 5.Particle size (mesh number) Also known as particle size, it refers to the number of meshes per square inch; in the actual tin powder production process, most tin powders are collected with several layers of sieves with different meshes, because the mesh size of each layer of sieves is different, so the grid of the particle size of the tin powder in each layer is also different, and the particle size of the finally collected tin powder particles is also a regional value. Particle Size Map of Solder Paste Therefore, the larger the mesh number of the solder paste is, the smaller the particle size of the tin powder in the solder paste will be; the smaller the mesh number is, the larger the particle size of the tin powder in the solder paste will be. That is, when the solder paste manufacturer selects the solder paste according to its mesh index, it should be determined according to the distance between the solder joints with the smallest distance on the PCB: if there is a larger distance, you can choose the solder paste with a smaller mesh size . Conversely, when the spacing between solder joints is small, solder paste with a larger mesh size should be used, and the general particle size is about 1/5 of the opening of the SMT stencil. 6.Viscosity In SMT workflow, from laser stencil printing (or spotting) of solder paste to attaching components to the reflow heating process, there is a process of moving, placing or carrying the PCB; To ensure solder paste not deformed, and the components attached to the PCB solder paste are not displaced. It is required that the solder paste should have good viscosity and hold time before the PCB enters reflow soldering heating . Among them, 200-600Pa·S solder paste is more suitable for needle-type or highly automated production process equipment; the printing process has relatively high requirements for the viscosity of solder paste, so the viscosity of solder paste used in the printing process is generally around 600-1200Pa·S . Suitable for manual or mechanical patch screen printing. High-viscosity solder paste has the characteristics of good solder joint accumulation effect , and is more suitable for small-pitch printing ; The low-viscosity solder paste has the characteristics of fast falling speed, tool-free cleaning, and time-saving printing ; Reminder: The viscosity of the solder paste will change with the stirring of the solder paste, and the viscosity will decrease when stirring; stop stirring, and the viscosity will return to the original state; this is very important for how to choose different viscosities. Solder paste plays a very important role. In addition, the viscosity of solder paste has a great relationship with temperature. Under normal circumstances, its viscosity will gradually decrease with the increase of temperature. 7.Storage stability We need the solder paste to have a stable quality , but in practical applications, the stability of the solder paste will change from purchase to storage and storage for a period of time. 8.Printing stability In the actual production process, the performance of reflow soldering is also very important, which has a great influence on the quality . 9.The final effect of soldering It mainly includes the following four aspects: good wettability, less BGA fusion and poor fusion, preheating collapse, and recovery ability after printing stop. Solder wetting is part of the process by which the metal in the solder bonds with the metal on the printed circuit board (PCB) or component . In a comparison with different solder pastes, you will find that A is more wetting than B. Comparison Between Different Solder Pastes In the BGA process, due to limited conditions, the fusion ability of solder paste is more important. The higher the degree of preheating collapse, the lower the incidence of poor bridging. You can find that there is no collapse in the left picture, that is, 0.3mm/0.2mm, but there is a collapse in the right picture, that is, 0.4mm/0.3mm. Excellent shutdown recovery can improve printing production efficiency to a certain extent. From this photo, you can see the difference curve after stopping for an hour. To sum up, we can know that choosing the right solder paste should not only consider the characteristics of the solder paste itself and its impact on quality and production, but also consider various factors in mass production . Therefore, it is necessary for us to continuously record and summarize the impact of solder paste from various suppliers on products in actual production.
February 13,2023READ MORE
- BLOG
How to choose a good ems supplier to reduce the cost of pcb assembly
Choosing a good EMS (electronic manufacturing services) supplier is an important step in reducing the cost of PCB assembly. An EMS supplier provides a range of services related to the manufacturing of electronic devices, including PCB assembly, component sourcing, and testing. By carefully selecting an EMS supplier, you can ensure that your PCB assembly process is efficient and cost-effective. One of the key factors to consider when choosing an EMS supplier is their experience and expertise in PCB assembly. The supplier should have a proven track record of successfully assembling PCBs for a variety of applications and industries. They should also have the necessary equipment and processes in place to handle the assembly of your PCBs in a timely and cost-effective manner. Another important factor to consider is the supplier's ability to source components for your PCB assembly. The EMS supplier should have established relationships with a variety of component manufacturers and distributors, allowing them to quickly and easily obtain the components needed for your PCB assembly. They should also be able to provide the necessary documentation and certification for the components to ensure that they are of high quality and meet the required specifications. In addition to experience and component sourcing, the EMS supplier should also be able to provide testing and quality assurance services for your PCB assembly. This includes ensuring that the assembled PCBs meet the required specifications and performance standards, as well as performing any necessary compliance testing. The supplier should also have a robust quality management system in place to ensure that the PCB assembly process is consistent and reliable. One of the key ways to reduce the cost of PCB assembly is to choose an EMS supplier that offers flexible pricing options. This may include volume discounts for large orders, as well as the ability to adjust the level of service provided based on your specific needs. For example, you may be able to reduce the cost of PCB assembly by providing the components yourself, or by using your own testing equipment and processes. In addition to considering the EMS supplier's experience, capabilities, and pricing options, it is also important to evaluate their communication and collaboration capabilities. The supplier should be able to work closely with you to understand your specific needs and requirements, and to provide timely and accurate updates on the progress of your PCB assembly project. This will help to ensure that the PCB assembly process is smooth and efficient, and that any issues or challenges can be quickly addressed. Overall, choosing a good EMS supplier is an important step in reducing the cost of PCB assembly. By carefully evaluating the supplier's experience, capabilities, pricing options, and communication and collaboration capabilities, you can ensure that your PCB assembly process is efficient, cost-effective, and of high quality.
December 9,2022READ MORE
- YYfab'Circuits
What is DFM Manufacturability Analysis
1. What is DFM? DFM manufacturability analysis is actually a bridge between R&D and production, communicating between them, and to mak e better products at a lower cost by simplifying , optimizing , and improving product design DFM manufacturability analysis means that manufacturability is considered from the time of product development and design, so that design and manufacturing are closely linked, to achieve the goal of succe ss from design to manufacture without any problem . The specific situations are as follows: Identify potential problems during the design phase and provide solutions Component design error avoidance Make appropriate component substitutions if any chance to improve component quality or reduce costs while meeting the original needs Improve the productivity in production processes and component quality Reduce the cost of product production 2. Why is DFM so important? The goal of the enterprise : low cost , high output , good supply capacity , and long-term reliable products . That means to produce better products with less money, and DFM can meet the needs from enterprises to a large extent. DFM is critical for efficiency, speed and high productivity. Many people believe that about 70% of product manufacturing costs come from the initial design stage, such as materials or manufacturing, so DFM has a great ability to reduce costs. In addition, DFM can also play a role in the entire manufacturing and production process. The influence map of each cycle of the p r oduct (from the Internet) Here are a few specific points: With DFM, production costs can be reduced Accelerate the time to market Reduce development costs Reduce the number of revisions or do not require revisions, reducing development costs Reduce rework and rework costs Find errors and glitches, and avoid them Provide a higher quality product as the design can be improved and enhanced at each stage From the perspective of engineers, DFM manufacturability analysis saves engineers a lot of trouble. No need to be urged by the boss, no need to stay up late to change the board, no need to bear the pressure of many parties, and can also reduce the number of times been bullied. Application of DFM in each stage of product 3. What would happen without DFM? In order to assemble printed circuit boards as quickly and efficiently as possible, it is important to design according to DFM requirements. Here are a few common problems that may arise if DFM manufacturability analysis is not performed. Importance of DFMs Haven ’ t done a better choice for material price and availability The price of electronic components may vary depending on the channel , which may have an unexpected impact on PCB assembly. Although this has little impact on the sample cost, once it is put into production, the cost will rise rapidly . For example: if you spend $1 more on electronic components that have been used 10 times in the design, you can ignore adding $1 to one board, but if it is 10,000 boards, it will be $10,000. If all the components on the PCBA are considered, the difference of $1 will also generate a huge cost difference. This is just a example, but in more cases, the board may be far more than 10,000 pieces. Of course, not only the price, different suppliers and distributors will also have different changes in the application of components . If the price of the material is low, but it is not available during production, it may face huge manufacturing delays. Especially at the end of the product production cycle , if the material is marked as not meeting the new design, service life is not up to standard, or obsolete, it is necessary to redesign the circuit board to adapt to the updated material , and may have to stay up all night to change the board . patch map PCBA assembly failed If the material does not match the PCB, it will cause many errors in the manufacturing process. Here are a few common ones: B ad solder joint Components that are not properly rotated for wave soldering can create bad solder joints, which may happen to the via holes and surface mounted(SMT) components. The position of components is also important, because some components may prevent good solder from being used to the other parts, causing worse connection. Solder Bridge Surface mounted pins that are very close may have a thin strip of solder between them. These solder strips may cause intermittent shorts that are difficult to find and correct. Tombstone Discrete SMT parts that are thermally unbalanced between their pins may have problems going through a reflow oven, this imbalance can pull out one of the pins and pull the part up until it stands upright like a tombstone. Floating Parts If the pad size is wrong, reflow SMT components may float misaligned, which may cause interference with other circuits Of course, here are just a few, in fact there will be more problems, any materials that cannot be matched correctly may need to be manually soldered or even redesigned, which means slowing down the manufacturing speed of the circuit board and spending more time and money. Tin dipping chart of gold finger (picture comes from the Internet) Reliability design Designing for reliability is also a common problem where circuits are designed without consideration for PCB assembly and practicability. Assuming that the product is used outdoors, it must be resistant to high temperature, but it was not considered at all during the design. Such a product did not meet the standard at all during the test, and then began to redesign, select materials, and other questions may appear in subsequent production. Manual welding component diagram 4. How to apply DFM in product production? Start with the schematic diagram When designing the schematic diagram, the designer will choose the required materials , usually based on the function to be realized, but many other factors must also be considered, including the price , reliability and life cycle of the material . If you start thinking about it at the design stage, it will save a lot of trouble, and avoid the trouble of the manufacturer. Here I have to talk about BOM. There are many matching materials on the market, which can actually solve a lot of problems.While there will be a little bit trouble when it comes to the production stopped, you need to consider the alternative selection. schematic diagram PCB layout PCB layout is also an important part of design, and in the early stages of design, important decisions about how to set up the board also directly affect how the board is manufactured. Single-layer board, double-layer board or multi-layer board? Two-layer boards are usually used for signal integrity and thermal management , while also considering the manufacturability of the board . For example, determining the board thickness required for the vias used with the optimum drill aspect ratio, which requires using a different board material or changing the number of layers of the board. Circuit Board model outline Determine the model and outline of the PCB, requiring detailed circuit board shape and size , including placing fixed components, through holes , slots , etc. Care must be taken here so that redesign and assembly errors can be avoided. Materials To avoid soldering problems during assembly , it is necessary to have the materials ready. Place and route according to DFM requirements PCB component placement and routing requires layout with the shortest signal paths in high-speed and power circuits for best electrical performance. When laying out a board , it is important for the PCB designer to strike a balance between the electrical and manufacturing needs of the board . Mainly pay attention to the following points: Points to note Description SMT In order make the chip mounter automatically assemble components, it is necessary to keep a certain distance between the components. Of course, manual soldering cannot be avoided sometimes. Wave soldering Both the DIP and SMT components need to be placed perpendicular to the direction of the circuit board through the solder wave, which is conducive to the even distribution of solder around the component pins. The placement of the DIP components will also affect the solder. For example, when the DIP and SMT components are on the same side of the PCB, reflow soldering will be performed before wave soldering. Reflow soldering The two pins of a smaller discrete SMT part need to be thermally balanced for reflow soldering. When a pad is connected to large area metal, it can act as a heat sink and cause the solder paste on that pad to reflow more slowly than the other pad, causing part tombstoning. Pad size is also a problem, as pads that are too large may cause parts to float out of alignment, while pads that are too small may not hold enough solder paste to reflow into a solid connection. PCB Package Vias that are too large for their pins can scatter solder through them too quickly, resulting in poor solder connections. SMT pads that are too large may contain too much solder paste, which can bridge to adjacent pads and cause shorts. Pads that are too close together are also prone to solder bridging. This often occurs in fine pitch components where there is not enough solder layer between pads to prevent bridging. Design finalization and documentation In addition to place and route, there are many other tasks during PCB layout that affect board manufacturability: Points to note Description PCB Testing To verify the accuracy of the assembly process, circuit boards often include test points accessible to the probes of the test fixture. However, if test points were not included in the original design, the board must be redesigned to add them before it can go into production. A redesign like this is not only costly and time consuming, but it may also generate new DFM issues that didn't exist before. Silkscreen and PCB marking Silkscreen marking is important for PCB testing, rework and debugging. If the necessary information is not on the board, manufacturing can be slowed down,meanwhile rework and testing technicians need to look for specific parts or polarity markings. Design summary drawing Without complete and accurate information on design revisions, time may be wasted when verifying manufacturing details, or even worse, errors can be made during board production.
December 7,2022READ MORE
- YYfab'Circuits
What is PCB Solder Mask Opening Window
Solder mask is a layer of PCB oil that covers copper and PCB material to insulate and protect the outside surface of the PCB from short circuits and the environment. Opening windows are necessary on the solder mask to allow the PCB pads to be soldered or connected and enables heat dissipation for some vias that are not covered with PCB ink. These openings on the solder mask are solder mask openings. During PCB design, you should be aware that solder masks are those empty areas without electronic components. During the production, these blank areas are printed with green, black, white or other PCB inks. The solder mask opening is to remove the paint layer on the circuit, which gets the tin exposed on the circuit. Technique for Solder Mask Opening 1.The solder mask opening of the PCB pads PCB pads are used to connect surface mounted electronic components, such as resistors, capacitors, ICs, etc. Therefore, PCB pads should not be printed with PCB ink, which means when you design the printed circuit board, you should create a solder mask opening for each PCB pad in the solder mask. 2.Solder Mask Opening of PCB Through Hole Whether PCB through holes require solder mask openings depends on the needs of your printed circuit board. Normally you can design solder mask openings for PCB through holes for better heat dissipation. Especially for power PCBs that carry large currents, solder mask openings for heat dissipation are widely applied.You can also fill the solder mask openings with tin, which acts as a metal heat dissipation. Solder mask openings for PCB through-holes can also be used as PCB test points due to the exposure of copper. The above are the two purposes for PCB through solder mask openings. Besides, PCB through hole can also use solder mask to protect copper from oxidation, especially in corrosive environments. 3.Solder Mask Opening of Gold Finger PCB gold fingers are a row of exposed hard gold-plated pads on the edge of the PCB for plugging and connecting. Solder mask openings are necessary for gold fingers because solder mask is insulating and gold fingers are used for connection and need to have excellent conductivity. Without solder mask, you don't need to worry about the oxidation of gold fingers. Surface finishing, hard gold plating protects the copper pads well. 4.Solder mask opening for groundingpoint You can design solder mask openings for the PCB grounding point, and the exposed copper can be connected to the metal case. 5.Solder mask opening for copper thickness measurement In the PCB manufacturing process, we need to measure the copper thickness of the PCB to see if it is qualified. 6.PCB antenna solder mask opening PCB antennas transmit and receive RF microwaves and consume a lot of power. For high frequency PCBs, solder mask openings for PCB antennas are common because the antenna can dissipate less power. Solder mask opening design 1.Dimension design During PCB fabrication process, the solder mask opening size should be larger than the size of pad or copper area that are supposed to be exposed. The PCB oil around the solder mask opening will melt together and the exposed area will be smaller. Typically, the size of the solder mask opening is 4 mils larger than the pad. Is it necessary to set the solder mask opening size during PCB design? No, you just need to keep the same size as the pads/vias that are supposed to exposed, since the EDA tool will automatically enlarge the solder mask opening size. 2.PCB solder mask opening method In PCB design, the solder mask opening can be set on the top and bottom sides of solder mask layers. Top and bottom solder mask green oil layer: The solder mask green oil of both top and bottom sides is used to prevent tin from getting on copper foil and maintain insulation. Solder mask opening can be placed on this layer to pads, vias, and non-electrical traces. In the PCB design, the pads will be openedby default (OVERRIDE: 0.1016mm), that is, the pad exposes the copper foil and expands by 0.1016mm. During the wave soldering process, it is recommended not to make any design changes to ensure solderability. In the PCB design, the vias willbe opened by default (OVERRIDE: 0.1016mm), that is, the vias expose the copper foil, enlarge by 0.1016mm and will be wave soldered with tin. If the design is to prevent solder paste from sticking to solder mask, you must select the penting option of solder mask to turn off solder mask. In addition, non-electrical tracescan also be puton this layer separately, so that the green oil can be blocked and the windows can be opened accordingly. If on the copper foil trace, it will be used to enhance the overcurrent capability of the conductive trace. Tin will be added during the soldering process. If using a non-copper trace, typically used for logo and special character screen printing, you can omit it to create a character silk screen layer.
November 17,2022READ MORE
