There are many technologies during the manufacturing process. By taking the time to review your designs before you create your layouts, you can resolve issues early enough to lower costs and production time. In order to understand what a good PCB library administrator can do for you, you need to know what they can't do, as well. When laying out printed circuit boards, we can fall victim to the same problem with our library parts. Many PCB design workflows rely on designers building their own component footprints for each layout. This is an important skill to have, but you will find yourself wasting a lot of time if you recreate the same parts over and over again for each job. If you are going to learn more information PCB library, check and read the content below.If you want to order PCB product, please check and custom your order online. What is the importance of PCB library？ When designing a PCB, each electronic component requires a symbol for the schematic capture, which describes pin functions, mappings and types, and a PCB footprint, to ensure that the component is soldered to the board correctly. Additionally, 3D models are also generally used by engineers to check clearances between their PCBs and their mechanical casings. High-quality libraries can be difficult to get right, but are an essential element of the PCB design process, because they ensure: · Proper and reliable manufacturing· Other CAD tool features function properly (ex: ERC and DRC checks)· Consistency, which makes designs readable and reusable Building a good PCB library comes with a number of challenges and difficulties, as discussed in Natasha Baker’s presentation. First of all, it’s a very detail-oriented process, where a high level of precision is necessary for each pin, pad, and part. Additionally, there is a lack of consistency in how datasheets are created, which can inadvertent errors during their interpretation. Lack of standards and industry alignment is another major challenge in building high-quality PCB libraries. Additionally, users or companies have specific preferences or requirements. Up until recently, most companies had their own standards, but nowadays we’re observing a shift in the industry towards creating and using more industry standards. Finally, a library’s importance is often underestimated and overlooked. All companies know it is important to have footprints that manufacture well, but in practice, prioritizing library maintenance over other critical tasks can be challenging. What are the features of PCB library？ Generally, a PCB library comprises some PCB footprints that typify both physical pad collections with some mechanical characteristics of the element or unit. One can selectively pick the PCB library he wants to incorporate into his design techniques. The reason one can pick from the PCB library is because there are different types. Different library strategies always meet different client exigencies. The PCB library requires that you understand how it works. One may get it all wrong if proper care is not taken. With the wrong PCB library set up, your PCB layout methods may fail you. The PCB library always needs factual or confirmed schematic segment ensign or totem. Also, it requires footprints that are quality so as to block weak or deficient fragments from landing on the production chains. One can know of these deficiencies via visual exploration. The footprints are important components of your PCB library. The kinds of sections an engineer selects in the course of designing matter so much. Various vendors come with several solutions when it comes to the PCB library. However, each tool that one uses differs based on the client. Different users have what is best suitable for them. Users should know that the moment your PCB library is perky, your panel unavoidably becomes thronged with details relating to the composite footprints of your library. What are the different types of PCB library？ There are different ways that PCB footprints can be organized in libraries that are external to the individual design databases: UseThese libraries are usually areas in a user’s personal account that have been set up to store component footprints, board outlines, and other design data. In some cases, they may be tied to the main library system, but usually, they are simply a “bucket” for a user to throw footprint models into. The advantages are that a user library is under the control of the individual designer without any bureaucracy. This makes for a very fast and efficient library system where the user can save and edit model files as needed. ProjectMany corporations will split off their libraries by projects. This becomes useful when the same part needs different sized footprints between projects due to different manufacturing methods. Project libraries are also helpful for storing project-specific data such as layer stackups for specific designs. These libraries are usually monitored and maintained by a CAD librarian to ensure quality. The advantage of this library is being able to select the correct version of a part for a specific design. For instance, boards that are built for RF designs sometimes have footprints that are slightly smaller for high-speed signals even though there are trade-offs in manufacturing. With a project library, the user can choose an RF version of a part that might be configured differently than the standard version. CorporateThis is the main or “master” library in a company that is used for PCB design. The footprint models in this library are usually closely monitored by the company librarian, and there is an elaborate method of checking and validating them before they are available for the designers to use.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 09/08/2021 09:26
Thermal Relief PCB
Managing and conducting heat is important to PCB. Most circuit boards will have large areas of metal for power or ground planes, and those planes will typically connect to several component pins. And if you are looking for the professional knowledge about thermal relief PCB, welcome to check and read the content we prepare for more information.If you want to order PCB product, please check and custom your order online. What is the definition of thermal relief PCB？ In the area of PCBA, managing and conducting heat is essential to a circuit board's overall design success. Nearly all PCBs utilize large areas of metal for ground planes or power planes, and these planes will generally connect to numerous component pins. When these pins are the leads for a thru-hole device, unsoldering or soldering these pins can pose a high level of difficulty with the significant amount of metal in the planes. This brings about the need for thermal relief. Thermal relief for a PCB comes in the form of a thermal relief pad or thermal pad. These thermal relief pads are PCB pads that are connected to a copper pour using a thermal connection. Whether your PCB design is a simple single-sided board or an intricate multi-layer board, there will usually be some significant areas of metal on it for power conduction and ground. The metal can be a network of traces, or maybe a sizable, filled power plane. Thru-hole component pinsThese pins may not get enough heat to solder correctly, resulting in a cold solder joint. Additionally, trying to unsolder a thru-hole that is soldered directly to large areas of metal could force too much heat to be applied to melt the solder. This excess heat could potentially damage nearby traces or components. Surface mount component pinsSmaller two-pinned SMT parts may also have problems if one of their pins is trying to solder directly to a large area of metal. The unbalanced metal between the pins could result in the solder melting faster on one side than the other, pulling the part up and away from the other pin. Why thermal relief PCB is important? Thermal relief plays a vital role while creating your circuit design. You can use the thermal relief pad anytime when you connect the negative plane to the thru-hole part. You know that the thermal relief pad has a varying number of spokes with different width based on how much power requirements are needed for a pin. A power pin, requiring a 40 mil trace and connecting a plane, must have the pad with four 10 mil spokes. However, the question is- Do your PCB vias need these thermal relief pads. The major reason for using this pad is to maintain a balance of the heat-sinking activities of pins soldered into planes. As the vias do not get the component pin, it does not need any relief pad with thermal properties. It will establish a link to the plane. What are the guidelines of thermal relief PCB？ Are you going to deal with thermal relief PCB? Then, you must know some relevant guidelines to avoid mistakes. · You have to use thermal pads while connecting your thru-hole pin to the power place, metal fill, and other bigger metals. · You must know how much power the pin can conduct. Based on this factor, you can identify the width and number of spokes. You can achieve 40 mils of spokes with 4 spokes. Each of these spokes must have a width of 10 mils. · SMT components directly soldered to the big metals must have some thermal relief between the metal and solder pad. · In a few cases, you may not be able to connect all spokes to the thermal relief pad. The congestion of thermal reliefs can result in this problem. Moreover, when the metal has very limited space, and you use thermal reliefs in the split plane, you will encounter this problem. You have to ensure that the chosen software has its own rules to detect minimum connections of thermal reliefs. · It is essential to know about the terminologies related to components and pads. · Termination and termination width– Termination refers to a metallization band present at the chip component’s end. The termination’s width is about the dimension across the chosen component. · Tolerance– It is about how much pad is used under your component. · Overlap– The component termination covers a pad surface known as overlap. The overlap has a length that includes tolerance. So, be sure to enlist the assistance of one of your company's greatest assets--your contract manufacturer. Be sure that your CM has the necessary experience in building the types of PCBs that match your company's needs. With heat management and thermal relief being vital to circuit design, ensure your CM understands the intricate details of proper thermal relief.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 09/07/2021 09:16
PDN in PCB
Do you know the importance of designing a good power delivery network (PDN) into our PCB?They are no less damaging as an incorrectly designed PDN can cause intermittent problems to outright failures of the circuit board. If you are curious about it, please check and read the content we prepare below. Let’s dive into the importance of how we design the power delivery network of our circuit board with this—your PDN design guide.If you want to order PCB product, please check and custom your order online. Why PDN is important to PCB? In PCB design, DC analysis is vital as numerous factors combine to exacerbate the problem of power integrity. Core voltage levels continue to drop; 1.2V and less are now common. As voltage is reduced, current requirements typically increase (IR drop = I * R). The miniaturization of electronics results in fewer layers and higher densities, thus reducing the available area for power nets. And antipads around vias perforate the planes and can overlap, creating the “Swiss cheese” effect. In addition, there are the power delivery network (PDN) challenges for a PCB designer, starting with the multiple instructions from hardware designer or power integrity (PI) engineer that are communicated by email, phone call, rules of thumb, etc. The designer must apply all of those instructions and rules to multiple power supplies. Having done that, the designer must then attempt to fulfill additional requests, such as “Can you shrink it by 20%?”, “Can you remove two plane layers and five capacitors?”, and that age-old favorite, “Can you do it yesterday?” Electromagnetic interference (EMI)The faster the circuitry became, the more sensitive it could be to EMI from both internal and external sources. One way to guard against EMI problems is to configure the power and ground planes to shield against both incoming and outgoing interference. Ground bounceWhen a lot of digital signals are switching states at the same time, it can produce an effect known as simultaneous switching noise (SSN) or ground bounce. This can be seen in memory or data buses, and if the rapid switching causes the signals to not return to their reference ground level, they will bounce above it. This effect can produce undesirable noise in the circuits that could potentially create false switching and disrupt the operation of the device. A well designed PDN can help control the reference ground level. Power ripplesSwitching may also be caused by a power supply, which will create noise, or ripples, in the circuitry. These ripples can manifest themselves as crosstalk in other circuitry, which can adversely affect the signals in those circuits. What is PDN impedance in PCB? Every electronic system has a PDN, which stands for “power delivery network”. It’s basically every element that is connected to the voltage and ground rail, including the power and ground plane arrangement, any buses that connect from planes to groups of components, decoupling capacitors used for power stability, and any other copper features that connect or couple to the main power rails in the design. Parasitics also make up the PDN impedance, such as parasitic capacitance and inductance in any connections to ICs. In particular, there are a few parasitic elements that are very important in determining the impedance of the PDN: · Plane capacitance - the capacitance between plane layers in the PDN.· Capacitor inductance - the leads on capacitors have some parasitic inductance, causing them to have a self-resonance.· Trace inductance - traces that bring power to components also contribute some inductance to the PDN. What is the importance of PDN impedance in PCB? The high speed and high frequency designers reading this will already know the answer to this question. However, with technological demands mounting, we’ll all be high speed and high frequency designers sooner than we like, so it is important to understand how PDN impedance affects the behavior of signals in your PCB. Unfortunately, we don’t always do the best job of placing this information in one place, so I’ll happily do this here. In short, your PDN impedance will affect the following aspects of your circuits: Power bus noise The voltage ripple created due to transient currents in your PCB. Note that, because your PDN impedance is a function of frequency, the voltage ripple caused by a switching will also be a function of frequency. Note that these transients can arise regardless of the level of noise in the output from your voltage regulator. Damping in power bus noiseAny ripple on the power bus could appear as ringing (i.e., an underdamped transient oscillation) in some cases. This is one problem that can occur if your decoupling capacitor is incorrectly sized or if you do not account for your decoupling capacitor’s self-resonance frequency in your decoupling network. Required level of decouplingMost capacitors have become insufficient for ensuring decoupling in PCBs with fast logic due to their relatively low self-resonance frequencies (~100 MHz). Therefore, designers used interplane capacitance to provide sufficient capacitance to ensure decoupling. Newer capacitors with GHz self-resonance frequencies are also available, and the combination of these is used to provide decoupling in high speed/high frequency PCBs.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 09/07/2021 09:09
Differential Pair in PCB Design
Before we can start routing the PCB, we need to define Design Rules for our differential traces. To get the correct parameters, we have to use the specifications from our PCB house and the provided calculator. This will give us the appropriate trace width and trace separation for the desired differential impedance. In this case, we want a single ended impedance of 50 Ohms and a differential line impedance of 100 Ohms. In this passage, we will focus on the differential pair in PCB design. If you are going to learn more information, you can check and read the content below we prepare below.If you want to order PCB product, please check and custom your order online. What is the basic of differential pair in PCB design? If differential pairs are so difficult to rout, then why invest the time and effort to use them? The answer is that differential pairs are naturally resistant to common mode noise, have little return through the grounding plane, minimize signal loss and increase the signal-to-noise ratio (SNR). They are also routed close together, meaning that outside noise shifts the signals in the pair by approximately the same amount, thereby increasing their noise rejection. Furthermore, because current returns through one of the traces, very little actually flows through the ground plane to elsewhere in your system. This means that when routed correctly, differential pairs can cross analog/digital planes and power boundaries without causing too much EMI. What are the advantages of differential pair in PCB design? So why use differential pairs when we are so use to routing traces the good ol single ended mode fashion? Well when going high speed, all sorts of noise and electromagnetic interferences start to crop up in the circuit that degrades our signal. So basically we use this technique to for the following reasons: · To minimize electronic crosstalk,· Attenuate Electromagnetic Interference,· Reduce both noise emission and noise acceptance,· Improvement in Signal to Noise (S/N) ratios,· Effective isolation from power systems,· Low power requirement. It is because of these awesome benefits that they are used in the popular and familiar communication protocols such as SATA, LVDS, PCI-E, DDR, 10gig Ethernet where the data-rates can range between 1.5Gbit/s to around 10 Gbit/s. What are the factors of differential pair routing? Fan-out and end routingLet’s start at that differential driver on the left (Differential driver). Imagine the TRUE ( TRUE differential driver) and COMPLEMENT ( Differential driver COMPLEMENT) outputs are adjacent balls on a fine-pitch BGA, fanned-out to inner layers. Whatever else you do, keep the track lengths to fan-out vias equal, and then keep the lengths after those vias equal until you start the parallel track pattern. That parallel track pattern is the coupled section because there’s an electromagnetic coupling between the two sides. Corner angles and curvesIf you only want good signal integrity, make no corner tighter than 135°. Many device application notes tell you the same. That angle works well for 45° routing. You’ll hear that curves give you better signal integrity, but for most PCB tracks – even for very fast signaling – that isn’t true. Get curves wrong and you’ll make it a whole lot worse – and what “wrong” means isn’t always obvious. Matching to other differential pairsAdd length in coupled sections only, and keep the pair coupled all the way because the differential impedance and delay-per-unit-length are different from the single-ended values – even within the same pair. Matching between a differential pair and single-ended signalsIn this case, you almost invariably need to add length to the pair, not the single-ended signal. As with matching between pairs, add length in coupled sections only. The application notes or standards docs will tell you how much. What are the guidelines of PCB differential pair routing? Route the different pairs togetherThe two traces of the pair need to be clearly identified as a diff pair for the layout team so that they are routed together across the entire length of the signal. · Avoid using vias if possible. If you do use them, they should be placed in symmetrical pairs. Try to keep them as close together as possible and place the vias equally from the pads that they are routing from.· Inner layer routing is preferable to minimize crosstalk, but that means transitioning through the layers with vias.· Keep the diff pairs isolated from other traces. This is often done by specifying a clearance of three times the normal trace width spacing.· If possible, consider broadside diff pair routing on adjacent signal layers. This will allow for higher routing density and better crosstalk control. Keep the routing symmetrical between the two tracesA successful diff pair should result in the lines closely mirroring each other. To do that, consider these ideas as you route: · Plan your routing to avoid obstacles such as vias or passive parts to maintain the symmetry of the pair (as shown in the picture above).· Plan your pad entry and exit routing so that the traces mirror each other as closely as possible.· Use the same trace widths throughout the length of the trace.· Keep the spacing between the pair consistent. Keep the trace lengths of the pair the sameAs discussed previously, the lengths of the two lines in the pair must be the same length. To achieve this, you may have to put small sections of trace tuning into the shorter line to equalize them. Although this will alter the symmetry of the lines slightly, the length is more important. If the unequal lengths are because of non-symmetrical pad locations, try to add your trace tuning in this area of the lines.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 09/06/2021 10:02
As a very important process of PCB manufacturing, drilling plays an essential role to affect the performance and quality of the finished products. When holes are drilled typically on a board base to thermally and electrically connect the board layers is known as drilling on a circuit board. These holes when connects the board layers is called vias. The main purpose of performing a drilling operation in the PCB fabrication process is to insert a through hole component lead or to connect the board layers for developing smooth circuitry on the PCB. In this passage we will tell you everything about PCB drilling if you are interested in it, please check and read the content we provide to learn more professional information.If you want to order PCB product, please check and custom your order online. What are the technologies of PCB drilling? This drilling process is made easy with the innovations in technologies over the years. Now PCB drilling can be done with small diameter drill bits, automated drilling machine, CNC drilling machine and many other effective drilling types of machinery that can suit with the PCB manufacturing of multiple type of circuit boards. Automated drilling machine can drill the holes in the circuit board by controlling the drilling operations with a computer. When many holes need to be drilled of different sizes and diameter, CNC machine is one of the effective solution saving time and cost of production. In case of drilling registration holes to make sure that further drilling performed on the center of the internal layer pads will be precise, an x-ray drill is used. This technology is used when via holes are linking copper layers together and holes are drilled on the leaded components. In case of vias with very small diameter, using mechanical drill bits caused increasing of breakage on the circuit board in turn increasing the cost. When very small holes are drilled in, the board and connected with the board layers, they are termed as micro vias. One of the extensively used drilling technologies in current times is CO2 laser drilling, which is used for drilling and processing internal layer via holes. In case of holes to be drilled for connecting only some copper layers instead of passing through the whole circuit board, one can go for a controlled depth drilling or performing pre-drilling on the sheets individually before PCB lamination or laser drilling mechanism. It is recommended to take the help of PCB drilling experts at the initial stage of the PCB project while deciding on the PCB layout and technique of production in PCB manufacturing. What the different types of are via drilled in PCB? A raw circuit board can have many fabricated properties, including cut-outs, slots, and the finished board’s overall shape. The largest number of such properties will be the holes that are drilled into the board. The purpose of these holes can be broken down into three categories: Via HolesSmall holes plated with metal are used to conduct electrical signals, power, and ground through the board layers. These holes are known as vias, and they come in different types depending on what is required: Thru-hole: This is the standard via, and it goes through the entire board layer stackup from top to bottom. These vias can connect to traces or planes on as many internal layers as needed.Buried: These vias start and stop on internal board layers without extending to an external layer. Blind: A blind via starts on an external layer but only goes partway through the board. As with buried vias, they are more expensive to fabricate, but they free up room for routing, and their shorter barrel can also help improve the signal integrity of high-speed transmission lines.Micro: This via has a smaller hole size than the others because it’s drilled with a laser. Component holesWhile surface mount parts are used for most active and discrete components on circuit boards today, many parts are still preferable to use with a thru-hole package. These components are typically connectors, switches, and other mechanical parts that need the more robust mounting that a thru-hole package provides. Mechanical holesA circuit board will usually have mechanical features or objects attached to it, such as brackets, connectors, or fans, which require holes for mounting. Although these holes are generally not plated with metal, they can be if the mounted feature requires an electrical connection to the board, such as chassis ground. In some cases, mounting holes are used to disperse the hot components’ heat to the inner plane layers. What are the considerations of PCB drilling? The drill press consists of a high-speed spindle, which rotates at speeds of about 300k RPM. These speeds are essential to produce the required accuracy for micron-level drilling on the PCB. To maintain accuracy at high speeds, the spindle makes use of an air bearing and a direct drill bit assembly, which is held by a precision collet chuck. Additionally, the vibration of the tip of the bit is controlled within a 10-micron range. In order to maintain the exact position of the hole on the PCB, the drill is mounted on a servo table, which controls the motion of the table on the X and Y-axes. A tunnel actuator is used to control the motion of the PCB in the Z-axis. As the pitch of the holes in the PCB assembly line is constantly decreasing and the demand for higher throughput is respectively increasing, the electronics to control the servo may lag behind at some point in time. The use of laser drilling to create through holes for manufacturing PCBs helps reduce or eliminate this lag and is the next generation’s requirement.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 08/31/2021 09:27
PCB footprints is very important process to PCB, There's more that goes into your PCB footprint checklist than the locations of pads on your components. Courtyard areas, component designators, and more are encoded in your component model and will appear directly on the PCB layout once you place a footprint. The PCB footprint is defined as the physical interface among electronic components or land pattern and printed circuit boards which also comprises of the information of documentation such as reference, polarization mark, and outline. In this passage, we will tell you everything about PCB footprint knowledge, and if you are going to learn more about it, please check and read the content below for more information.If you want to order PCB product, please check and custom your order online. What are considerations of PCB footprint? Every component that will appear on a circuit board layout will have a PCB footprint. Whenever you start a new project and jump into a layout, schematic symbols and PCB footprints need to be correct before a single design document is created. Every PCB footprint will contain the following elements: Pad or hole locationsThis shows where mounting pads (for SMD components) or mounting holes (through-hole components) are located. These locations are used for soldering and must be designed accurately. Courtyard and outlineThis act like a keepout area in your PCB footprint, i.e., other components cannot be placed within the PCB footprint courtyard. Reference designatorThis alphanumeric code provides a unique identifier of the component in your schematic and PCB layout. Pin-1 designatorSome components may have arbitrary orientation (e.g., QFP and DIP components). The pin-1 designator tells the assembler the correct orientation. MechanicalsSome components may have some mechanical element or overhang that might extend above a component and create a collision with other components. One example is a heat sink, which does not have an electrical connection to the PCB quote. These can be defined in a mechanical layer in your PCB layout. Link to 3D model and symbolsEvery PCB footprint has a corresponding schematic symbol, and it may need a 3D model. This lets you visualize the board in 3D and enables 3D clearance checking between components. What are the guidelines of PCB footprint? Components are the most important elements of the board, and pads are the points of connection. If the pad layout fails to accurately identify your component locations or isn’t arranged such that the component can be securely attached, the PCB cannot be assembled. If the pads don’t line up properly with other surface elements like traces and drill holes, your board will not function properly or at all. Foot print pad layout Footprint pad guidelines are rules or suggestions that stipulate how pads should be spaced from other pads, other surface elements, drill holes and the board edge. They also define how pads for a single component should be arranged. Start with exact informationEnsure that you have the correct specifications for the part and the relevant standards, such as IPC-7351, to use as a blueprint. Build the footprint from the ground upStart first with the pad information. Whether your tools require a separate pad part, or you must add the pad geometry as an attribute, ensure you have what you need first. Next, create the body outline of the component at the maximum material width. Finally, add silkscreen outlines, reference designators, other attributes, and STEP models to finish the footprint. Make sure to include all the required dataOften a footprint is left incomplete, which can cause problems during PCB layout. For instance, if your CAD tools require you to enter the part’s height as an attribute, don’t neglect this. Later on, you may wonder why you didn’t get a warning when you find out that your component is sticking up through the device enclosure. Be cautious of including too much dataDo your footprints need drawing formats, mechanical data, and dimensions? Remember that each footprint will be replicated for each instance of that part in the layout. If you have included all of this extra data, it will also be replicated. Viewing the CAD layer designated for footprint dimensions will result in a confusion of jumbled data that can be difficult to discern for assembly.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 08/30/2021 09:49
PCB Thermal Paste
Thermal paste is also called heat sink compound or thermal grease and conducts heat in the same manner as the thermal pad. While thermal paste is made out of similar materials as the thermal pads, it comes in a liquid form that can be manipulated to fit the area that requires the thermal interface material. Thermal paste between the heat-generating component and the heat sink will close any air gaps between the two. Are you interested in PCB manufacturing knowledge？Welcome to check and read the content below for more about it to learn more professional information. Let’s go!If you want to order PCB product, please check and custom your order online. What is the basic introduction of PCB thermal paste? The most generic definition for thermal paste is that it is a paste chemically constructed to allow for heat transfer. Its composition is a liquid polymer, that may include urethanes, acrylates, silicones and epoxies. The most typical function for thermal paste is as a filler between two surfaces to provide a solid interface and increase the volume of heat transfer between the surfaces. With this primary function it may be surprising that the heat transfer rate may range from approximately 3W/(m·K) to 13W/(m·K) for non-metallic pastes, which is far below the 385W/(m·K) for 99% pure copper. Why PCB thermal paste is important for manufacturing? It is well-known that the removal of excess heat from components or parts that tend to generate high temperatures is critical during electronics operation. Heat sinks that can have thermal conductivities greater than 200W/(m·K), are common for these components, which include CPUs, GPUs, power transistors and other high-performance semiconductor-based devices. During operation, the greatest source of heat on circuits boards is generation by components. And the heat removal techniques implemented are done so during PCB assembly. However, the assembly process itself introduces heat to the board, which also should be a design consideration. There are two heat transfer issues, dissipation and distribution. To be most effective, thermal paste should fill in all of the gaps between the two surfaces at which it is applied. Additionally, it is desirable that the paste not conduct electricity away from the component. Another important consideration is operational lifetime. For thermal pastes, typical ranges are 3-5 years, which means that for many components it may need to be replaced. All of these factors must be considered if it is determined that thermal paste should be utilized for your design. What are the advantages of PCB thermal paste？ · Reliable· Inexpensive· Easy application· Fills gaps well· Thin layer Thermal paste is like an old swimming hole out in the woods. You know it’ll always be there, and it’s cheap, but things might get a bit messy. However, just like sunscreen is cheaper than skin cancer treatment, thermal paste is less expensive than PCB thermal pads. When to use PCB thermal paste？ Thermal paste also bests thermal pads when it comes to uneven surfaces. Since thermal paste is a liquid, it can fill large gaps more evenly than thermal pads. Some heat sinks or ICs have uneven surfaces where the TIM will be applied. If that’s the case for your PCB, thermal paste will provide better thermal conductivity than a thermal pad. Remembering which of your components need heat sinks can be a pain. Instead of straining your brain, let your PCB design software do it for you. Most design programs will let you add in comments on components. Attach thermal performance concerns to an electronic component to keep your PCB quote out of hot water. What are the applications of PCB thermal paste？ Carriers and fillersThe carrier material in a thermal paste is typically categorized as silicone or non-silicone type. Generally, manufacturers recommend using silicone-based pastes. Heatsink specificationThe surface finish of the heatsink is also a critical part of the thermal interface. Specifications for roughness, unevenness over distance, are to be considered along with the use of a baseplate for the component or module. Applying to component VS applying to heatsinkThe order of assembly during the production process will decide if you need to apply the paste to the component first or the heatsink. Preparation of pastePastes will have to be mixed before application to check for homogenization of the carrier and filler materials.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 08/30/2021 09:16
PCB Mechanical Stress
During the PCB manufacturing, there might be mechanical stress on the board. But, do you know what PCB mechanical stress is? Mechanical stress is the internal force that interacts with each part of an object when it is deformed due to an external cause (force, load, temperature, etc.) to resist the effect of this external cause, and tries to make the object from the deformed position. Revert to the position before the deformation. In this passage, we will tell you everything about PCB mechanical stress. Check and read the content below to learn how to overcome PCB mechanical stress.If you want to order PCB product, please check and custom your order online. What are the main types of PCB mechanical stress? The mechanical stress in the assembly manufacturing process mainly includes the following aspects: · The force acting on PCBA during the operation of tooling equipment.· The rapid difference between the cold and hot changes in the welding process on the PCBA force.· Tolerance to mechanical shock by collision and fall when PCBA board is taken improperly· PCBA packaging improper protection, tolerance to vibration in the transport process. How to reduce PCB mechanical stress? Obviously, PCB mechanical stress can be a significant problem during manufacturing. Therefore, it is imperative that you employ DFM guidelines and principles established by and acquired from the CM that will build your boards. Included should be DFA rules specifically targeted to the PCB assembly process. To optimize your PCB mechanical stress avoidance strategy, it is a good idea to incorporate the following guidelines, as well. Guidelines for Overcoming PCB Mechanical Stress Issues during Manufacturing · Avoid using moisture-sensitive components.· Do not push the boundaries of your CM’s equipment capabilities, as this may result in lower than desired yield rates.· Consider increasing board edge clearance when delicate components; such as tall electrolytic caps and glass body ICs, are used.· Attempt to design boards with the standard PCB thickness of ≅ 62 mil or 1.6 mm and ensure that thinner boards include mechanical support of fixtures during manufacturing.· Strive for symmetry in your PCB stackup design.· Design for the minimum number of lamination cycles to prevent board failures during manufacturing or degradation that may result in a shortened lifecycle.· Make sure your fabricator uses quality materials with adequate resin venting and employs adequate wet-out.· Make sure your fabricator has a quality, consistent drilling process, including desmear procedure.· Opt for a PCB surface finish other than OSP, which is far easier to damage than other types.· Make sure your assembler employs good cleaning techniques.· Work with or allow your CM to define PCB panelization strategy.· Make sure to observe proper handling and storage protocols throughout manufacturing.· Ensure that adequate PCB inspection methods are utilized. What is the analysis of PCB mechanical stress? Structural and thermal integrity are critical design considerations for packages/PCBs that affect reliability and structural integrity. Thermal impact on the package, especially from the IC, is a key driver for material selection, cooling, and form factor decisions, that ultimately determine the size, weight and cost of the final product. It is critical for package and system designers to determine the thermal signature of their system. ANSYS delivers an automated design flow that streamlines EM-thermal coupled analysis and links to mechanical analysis to predict the structural impact on the electronic package. ANSYS Icepak performs heat transfer and fluid flow simulation enabling engineers to analyze transient steady-state thermal conditions and develop effective cooling strategies for all types of electronic applications including wearables and data centers. Unique to ANSYS is that we provide a comprehensive, integrated electrical-thermal-mechanical simulation solution. PCB problems can be broadly classified as electrical, thermal and mechanical. Power distribution problems include signal integrity, crosstalk and electromagnetic interference. Current flow in a PCB and through the electronic components causes power losses across the board and leads to power dissipation in the components, mainly the ICs. Power losses in conductors within the board and heat generated by ICs increase their temperatures, leading to thermal problems. Moreover, modern microprocessors can demand peak currents of 100 amperes or more. These high currents cause significant heat dissipation in the ICs and significant Joule or Ohmic heating in the connected power planes and traces. Even a small change in temperature can affect a device’s performance due to the inverse relationship between electrical and thermal conductivities. Temperature gradients across the board and components can produce mechanical reliability problems due to the cyclic nature of thermal transients. This follows from the principle of the bimetallic strip, which can convert temperature differences into mechanical displacement. Per this principle, when two metals with dissimilar thermal expansion coefficients are bonded together, they will bend if they are heated. This bending can cause solder joints to crack or even result in delamination of the board or traces on the PCB. With the ANSYS design flow you can perform DC analysis, calculate Joule heating then produce temperature profiles and associated mechanical deformation and stress. It’s a chip - package – PCB quote solution that allows engineers to evaluate electrical, thermal, and structural behavior.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 08/27/2021 09:24
Bare Board Testing
During the PCB manufacturing process bare board test is a very important to affect the performance and quality of the finished boards. And in this case, pushing your PCB into production with doing bare board PCB testing is a lot like being a puzzle manufacturer that isn’t checking for missing pieces. The result can still be angry customers, but in the PCB realm there is even the possibility of reworks, product recalls, or other collateral damage. If you are going to learn the professional knowledge about bare board testing, please check and read the content we prepare below. Let’s go!If you want to order PCB product, please check and custom your order online. What is the basic introduction of bare board testing? Simply put, it’s when you test the isolation and continuity of the electrical connections on a bare circuit board prior to attaching components such as ICs. For a quick review of EE 101: · Isolation testing involves verifying that the required resistance between two separate electrical connections is met.· Continuity testing involves verifying there are no open points within the circuit (i.e. no impedance to current flow). The idea is to ensure that the circuit part of the PCB is correct, by testing it to the expected electrical footprint of your design. These tests are generally applied under 100 milliamps with a threshold between 10 and 50 ohms. Why is bare board testing important to PCB manufacturing? PCB manufacturing is a complicated process where copper layers are etched and hundreds of holes are drilled according to a design. Even with the aid of machines, the results aren’t always perfect. Occasionally, you’ll have issues on a few PCBs that go undetected until they are assembled and deployed. For example, the etching process may leave a tiny piece of copper connecting two pads, or a trace may be disconnected due to mishandling or process flaws. Multilayer PCB manufacturing is even more complicated, which increases the risk of flaws on the bare board PCB. Today’s PCBs are smaller and more densely populated than ever before. Keeping track of all those traces, vias, and through-holes across a multilayer board has never been more challenging, and its important to know that your bare PCB is solid before you start soldering expensive components on top of it. Especially if you’re dealing with SMTs and fine line mounting technologies. While bare board testing may seem time consuming and costly at a glance, when taken in the context with the rest of production, the overall setup time, test duration, and cost are still pretty minimal. A little bit of investment into bare board testing upfront can save you time and money in the long run by avoiding field testing, repair, and maintenance costs further down the line. If you want to avoid the terrible fate of recalling dozens of products and compensating for the loss, you’ll need to test every single bare board PCB. It is the only way to ensure that they are schematically correct before the assembly process begins. Testing also drastically reduces the number of issues when you’re running functional tests later. What are the bare board testing capabilities? We currently have two different types of testing equipment available to test your circuit boards; we have a number of Everett Charles ATG test machines that are flying probe, fixtureless testers and we also have universal grid testing capability. These machines use fixtures built specifically for your PCB. Bare board testing involves using capacitance and resistance tests; each of our machines uses a combination of both. Capacitance testing for a bare board involves testing for opens and shorts by "charging" a net or plane and then probing each net to measure the induced capacity. Inaccuracies occur with this method because of the inherent variability in producing circuit boards. However field measurement or field effect testing for shorts uses a very similar approach. · 100% Net List Test: Check of every "node" on every net on the board.· Adjacency Test: Type of test for checking isolation between conductors - shorts test. A software generated program that checks for nets that are within a tolerance set by the user. Two methods are used - Proximity Adjacency and Line of Site Adjacency.· Clam Shell Test: Provides simultaneous testing of both sides of the board at the same time. These types of fixtures are used on single grid testers and dual grid testers. A very reliable method of bare board testing because all points are tested at the same time.· Combined Grid/Probe Testing: Using the flying probe test sequence to cover areas of the board with fine pitch, high density points while the grid test verifies power to ground separation, through hole and wider pitch component pads.· Comparative or Golden Board Test: Method using a "master" or known good board (KGB) to learn a program and then test other boards against the learned net list program. Poor choice for test accuracy - you may be learning a "bad" board.· Continuity Test: Verification that the resistance between test points is lower than the specified limit or maximum continuity resistance. See shorts and opens tests. How to process the bare board testing on PCB? Before you get the idea that you can assess your PCBs with a visual inspection only, I can assure you that it’s impossible to do so. Many of the shorts and disconnections are too small to be seen with the naked eye. Besides, it’s impossible to check multilayer connectivity with a visual inspection. There are two types of bare board PCB tests available: the fixture test and the flying probe test. The Fixture Test This involves developing a fixture containing multiple pins that match the number of nets on the circuit. It means that you’ll have two bed-of-nails fixtures pressing the PCB from the top and bottom with the hundreds of probes making a connection with the testing points of the PCB. The Flying Probe Test This uses two or more probes to test all the nets on the PCB. The probe moves along the X-Y axis according to the layout programmed on the testing panel. There is no need to develop a fixture for the flying probe test, which makes it the cheaper option. However, the flying probe test is comparatively slower.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 08/26/2021 10:29
Insertion loss in PCB
In this passage, we will provide an introduction to the cause and effect of insertion loss which becomes predominant as you push upwards from 3GHz. Energy is lost from a signal as heat in the conductor (the PCB trace and ground planes) resistance and as heat in the dielectric caused by the inherent material properties of the base material itself. In this passage, follow us and check the content to learn more professional information about insertion loss in PCB. If you are curious about it please read the content below.If you want to order PCB product, please check and custom your order online. Why insertion loss in PCB is important? At high frequencies signal loss produces signal attenuation and distortion; the signal will be attenuated by conductor resistance and leakage in the laminate material; a signal pulse will be distorted as loss unequally affects each of the signal harmonics. Loss is frequency dependent so each successive harmonic will be increasingly attenuated; the resulting amplitude and changes means the signal at the load will be a distortion of the original. What are causes of insertion loss in PCB？ If you’ve never worked with RF systems, Wave might sound like an esoteric buzz word. However, the principles involved in Wave design build on those used in lower-frequency designs. Just as is the case with any controlled impedance design, PCB insertion loss arises due to inconsistent impedance throughout an interconnect. This quantity represents the amount of signal that is transmitted at an impedance discontinuity along an interconnect. · Copper losses: Copper losses occur when the connector's conducting surfaces cause the power to become dissipated. This problem is usually the result of the plating and the material that is used in the PCB.· Dielectric losses: Dielectric losses occur when the dielectric materials used in the PCB layers causes the power to be dissipated.· Reflective losses: Reflective losses occur with the connector's voltage standing wave ratio (VSWR) when in transmission lines. It occurs when the power does not become accepted by the load, as it becomes reflected back along the line. For PCBs using lower speed rates, such as 3Ghz up to 5Ghz, a mismatch in impedance usually results in signal loss. Yet, with the higher speeds of 10Ghz to 30Ghz+, the materials used to create the dielectric constant will be the top issue that could be creating the insertion loss. To deal with these many issues, selecting the appropriate materials for the core, prepreg, and copper foil becomes essential when building the PCB stack-up. In Wave devices, by far the most prominent source of impedance discontinuities in any impedance controlled interconnect is vias. Layer transitions require some kind of via, whether it is a blind, buried, or through-hole via. Plated through-hole vias or stacked blind/buried vias are typical in traditional multilayer PCB designs. These structures have some parasitic with them, and these parasitic are responsible for producing PCB insertion loss at higher frequencies. If you look at a time-domain reflectometry trace for an Wave interconnect on a test coupon and calculate the impedance from the interconnect return loss, you’ll likely see a capacitive impedance drop at plated through-hole vias that are used for layer transitions. These impedance discontinuities are undesirable for two primary reasons. First, these capacitive impedance discontinuities at vias cause reflections, leading to the formation of standing waves and strong radiated EMI. Second, this reduces the signal level that reaches the downstream load (i.e., insertion loss). How to improve insertion loss in PCB？ Dealing with insertion loss can help you design the right high-speed PCB for your application. By understanding the main issues that create this signal loss, you can decide on the types of materials to use for the stack-up, the weave of the glass and resin density, and the thickness of the PCB. To recap on this topic, things to take into consideration for your PCB stack-up include: · Minimize skin effect and surface roughness of the copper foil by selecting low profile copper, very low-profile ED copper and alternative oxide.· Select tighter fiberglass weaves for better dielectric constants, or angle and zig-zag the copper traces over looser weaves for signal integrity.· Choose materials with low dielectric constants and flat frequency responses to handle the multiple signals.· Use the lowest loss dielectric materials, as well as shorter reaches, to deal with dissipation factors. What are the differences of insertion loss & connector return loss? A connector is one of many transmission line elements in a signal path between a transmitter and receiver in a multi-board system. When discussing interconnects, most designers tend to focus on vias as an inductive impedance discontinuity. In other words, a via in an interconnect acts like an inductor at high frequencies and can create some reflection if not designed properly. However, connectors also behave very similar to their own short transmission lines. They also have their own impedance that determines how signals interact with the connector. As much as we would like connectors to be perfect, the fact remains that they can create some return and insertion loss when placed in an interconnect. The primary mechanism that leads to return loss and insertion loss at a connector is an impedance mismatch caused by surface mount pads on a connector. Through hole connectors also incur some insertion loss as the pins act like inductive/capacitive impedance discontinuities . Once a signal reaches an SMD connector pad with wider copper, the per length capacitance in this segment of the trace is larger, which then decreases the characteristic impedance of the trace seen at the connector pad. This capacitive impedance discontinuity causes signal reflection and leads to connector return loss and insertion loss.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 08/26/2021 10:03
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