Interferensforanstaltninger i PCB-kredsløbsdesign

If you’re looking for interference measures in PCB circuit board design, you’ve come to the right place. These measures include shielding, grounding, transmission lines, and low-pass filters. These measures can help prevent EMI and noise, as well as improve the performance of your electronic products.

Shielding

Shielding is an important part of the PCB circuit board design process. It prevents EMI, or electromagnetic interference, from interfering with the circuit board. EMI is caused by electrical signals, which are often higher in frequency than the circuit board itself. Metal shields or cans on the circuit board help to block this kind of interference. Shielding is an important aspect of PCB design, regardless of whether the board is designed for analog circuitry or digital.

Typically, the shielding material is made up of several copper layers. These copper layers are connected to one another with stitched vias, and the shielding layer is sandwiched between them. A solid copper layer offers higher shielding, while cross-hatched copper layers provide shielding without compromising flexibility.

Shielding materials are often made of copper or tin. These metals are useful for shielding circuits, since they isolate them from the rest of the board. Shielding can also change the thickness of a flexible circuit. As a result, it can lower the bend capacity. Shielding materials should be chosen carefully, because there are certain limits to how flexible a circuit board can be.

Grounding

Grounding in PCB circuit board design is important to maintain signal integrity and minimize EMI. A reference ground plane provides a clean return path for signals and shields high-speed circuits from EMI. Proper PCB grounding can also help with power circuits. However, there are several factors to consider in PCB circuit design before you begin.

First, isolate analog ground points from the power plane. This can prevent voltage spikes on the power plane. In addition, distribute decoupling capacitors throughout the board. For digital components, you should use a decoupling capacitor of the same value as the power plane. Second, avoid distributing the ground plane on more than one layer, which will increase the loop area.

Ground planes should not be too close to the electronic components. Electromagnetic induction (EMI) causes signals to be coupled if two traces are placed too close together. This phenomenon is known as crosstalk. Ground planes are designed to minimize crosstalk and reduce EMI.

Transmission lines

Transmission lines are important to PCB circuit board design because they can affect the functionality of the board. A transmission line’s properties include characteristic impedance and propagation delay. When these parameters are not controlled, they may cause signal reflections and electromagnetic noise. This will reduce the signal quality and can compromise the integrity of the circuit board.

Transmission lines can be of different shapes, including striplines and coplanar waveguides. Each type of transmission line has a characteristic impedance, which is determined by the width and thickness of the conductive strip. Unlike other types of transmission lines, striplines don’t require a single ground plane, as their conductive strip may be embedded between two different layers.

Another type of transmission line is microstrips, which are typically used on the outermost layer of a PCB circuit board. These types of traces offer high characteristic impedance, which varies with frequency. This difference in impedance leads to reflection of the signal, which travels the opposite direction. In order to avoid this effect, the impedance must be equal to the output impedance of the source.

Low-pass filters

Low-pass filters are used to filter signals, such as radio waves, at low frequencies. Using capacitors as low-pass filters in a PCB circuit board design can improve the performance of a circuit. However, it is not always possible to use Rogers 4003 printed circuit board material, and it is not always available in the market.

Ferrites are commonly used as low-pass filters, but this material is susceptible to saturation when it is exposed to DC current. As such, it is not always possible to use it as a low-pass element if the circuit impedance is higher than the ferrite’s impedance.

Sådan lodder du chipkomponenterne

Hand soldering

Hand soldering involves applying heat and pressure to the component to form a strong bond. Unlike wave or reflow soldering machines, hand soldering is done by an individual with soldering iron and a soldering station. Hand soldering can be performed on smaller components or for repair and rework.

To begin soldering, hold the soldering iron tip on the chip’s lead or contact point. Next, touch the tip of the solder wire to the lead. Then, heat the lead and solder until the solder flows. Ensure that the solder covers the entire lead or contact point. To prevent tombstoneing, don’t hold heat on one side of the chip for too long. Otherwise, the solder will reflow onto the opposite side.

The hand soldering process is generally the final step of prototype assembly. When using a Thermaltronics soldering tool, you can finish fine details on both through-hole and surface-mount components. When using hand soldering, it is best to use a temperature-controlled iron. Using a non-temperature-controlled iron will not produce reliable electrical joints.

Through-hole soldering

Through-hole soldering is a process that entails putting together a component with lead wires. Lead wires are inserted into the holes using a plier, which is held against the body of the component. It is important to apply gentle pressure on the leads as they are inserted into the through-holes. This process ensures that the leads of the chip components do not become overstretched. Excessive stretching may affect the placement of other components on the PCB. Additionally, it can affect the appearance of the entire through-hole soldering process.

Before soldering, it is important to clean the chip component’s surface. To clean a chip component, you can use a 3M Scotch-Brite Pad or sine grade steel wool. It is important to use the correct soldering flux as water-soluble flux can oxidize the PCB or through-hole component.

Lead-free soldering

Lead-free soldering is a process that uses lead-free solder and a higher-wattage soldering iron. To achieve optimal performance, soldering temperatures must be high enough to transfer enough heat to the chip component. The temperature required depends on the component’s volume, thermal mass, and board tolerances.

The first step to lead-free soldering is determining if the chip components are compatible with lead-free solder. The process is not without complications. Some chip components are coated with a tin-lead alloy for solderability. However, this type of coating violates environmental legislation. Fortunately, some chip manufacturers have found ways to use lead-free solder with tin-lead components. This is known as backward compatibility.

Another way to make chip components lead-free is to use nickel-lead. Nickel-lead has been used for years with tin-lead solder. Another option is Ni-Pd-Au solder. However, Ni-Pd-Au is not wettable in the same way as tin.

Flux in lead-free solder

Flux is a pre-processing agent used during the soldering process. Flux promotes metallurgical bonds between chip components, so the solder joints will not break or fluctuate in response to stress. It also removes oxidation from surfaces, which facilitates wetting, the process of solder flowing over the surface.

Flux residues can lead to corrosion and dendritic growth on PCB assemblies. After soldering chip components, the residues should be cleaned off with a good flux remover. For best results, angle the board while cleaning it so that excess solvent runs off the board. A lint-free wipe or a horsehair brush can be used to scrub the board gently.

Flux is an important component of lead-free solder. It cleans the metal surface to ensure a good metallurgical bond. Bad solder joints can lead to costly component failures. Luckily, flux is a chemical cleaning agent that can be applied before soldering, and during the process itself.

Cleaning excess solder

When soldering chip components, it’s often necessary to clean excess solder from them. But it can be difficult to remove the solder that has already been applied. Once it’s adhered to the component, the solder will have already been heated two or three times. Each reheat changes the physical composition of the metal. As a result, the solder becomes increasingly brittle. To avoid this, it’s best to remove the old solder and replace it with a new one.

Another option is to use a braid of solder to remove excess solder from the chip component. To do this, place a braid of solder over the component, hold the soldering iron against the braid, and wait for a few seconds. Afterwards, remove the solder braid.

6 Basic Rules of PCB Layout

PCB layout involves designing a circuit with multiple layers. Some of the fundamental rules of PCB design are as follows: Avoid multiple ground planes. Make analog circuit signals direct and short. Avoid using three distinct capacitors on a single PCB. You can also read our articles on multi-layer PCB design and how to design a multi-layer PCB.

Designing a multi-layer PCB

When you are designing a multi-layer PCB, there are a few important things that you should consider. One of these is that the copper traces should maintain signal and power integrity. If they are not, then they could affect the quality of current. This is why it is necessary to use controlled impedance traces. These traces should be thicker than normal to prevent overheating.

Once you are clear on what you want, you can start designing the PCB. The first step in designing a multilayer PCB is to create a schematic. It will serve as the basis for your entire design. Start by opening a schematic editor window. You can then add and rotate details as needed. Make sure that the schematic is accurate.

Creating a single ground plane

Creating a single ground plane on a PCB layout helps reduce the amount of nonuniform voltages across a circuit board. This is accomplished by creating vias or through holes to connect the ground plane with other parts of the board. It also helps reduce noise produced by variations in return current.

While defining a ground plane on a PCB, it is crucial to ensure that the ground plane is not covered with conductive rings because this can lead to electromagnetic interference or even ground loops. Ideally, the ground plane should be located under electronic components. It may be necessary to rearrange the placement of some traces and components to fit the ground plane.

Keeping analog circuit signals direct and short

When implementing a PCB layout for analog circuits, it is important to keep the analog signal traces short and direct. In addition, analog components must be located near each other, which will simplify direct routing. Keeping noisy analog components close to the center of the board will also help reduce noise.

In addition to keeping analog circuit signals direct and short, designers should also avoid obstructing the return paths. Plane splits, vias, slots, and cutouts can cause noise as the analog signal seeks the shortest path back to its origin. As a result, the signal can wander near the ground plane, generating significant noise.

Avoiding three distinct capacitors

When designing a PCB layout, it is best to avoid placing three distinct capacitors on power pins. This arrangement may lead to more problems than it solves. One way to avoid three distinct capacitors is to use traces and coffer fill. Then, place them as close to the device’s pin as possible.

This is not always possible, however, since the distance between traces is not always what was calculated during the design phase. This is a common problem that can lead to problems during the assembly process. When considering placement, remember that the placement of each component is crucial to its functionality.

Using power layer copper

Using power layer copper in PCB layout requires proper planning. In this part of the board, you must allocate a specific area of the board for power network. You can also use inner layer division to allocate this area. To add this layer, you should use the command “PLACE-SPLIT PLANE” and then select the network to be allocated for split. Once you have the power layer area allocated, you can then use the copper paving technique to place the copper in the split area.

In addition to achieving even copper coverage, you must make sure that the thickness of the board is compatible with its core. Using the power plane symmetry alone will not guarantee a perfect copper coverage, as the copper in this part will tear when contour routing. Copper up to the board edge also will not be compatible with scoring (V-cut) techniques. To avoid this issue, it is recommended that you indicate the copper zone on the mechanical layer and that it has a minimum width of 0.5mm.

Using a list of guidelines to place components on a PCB

Using a list of guidelines to place a component on a PCB can help minimize the overall cost of developing a new product while shortening the product development cycle. These guidelines also help ensure a smooth transition from prototype to production. These guidelines are applicable to both analog and digital circuits.

Most board designers follow a set of guidelines when designing a PCB. For example, a typical board design rule is to minimize the length of digital clock traces. However, many designers do not fully understand the rationale behind these guidelines. Among other things, high-speed traces must not cross gaps in the signal return plane.

EMI Degradation After Filling An Irrigation Pump

There are two different ways to analyze EMI degradation after filling an irrigation pump: radiation and conduction. The EMI degradation after filling depends on the type of glue material and how the input grounding process is performed. The EMI degradation is worsened by ethanol and water.

EMI degradation after filling

EMI degradation after filling power supplies is often referred to as the ‘filling effect’, which describes the loss of EMI sensitivity after a power supply has been filled. The degradation is a combination of radiation and conduction. The ‘filling effect’ occurs because the materials that make up the power supply undergo a series of changes. Some of these changes may be undesirable, while others can be beneficial.

Unwanted electromagnetic energy (EMI) is radiation that propagates into space through inductive and capacitive coupling. This unwanted energy is harmful to electronic devices and affects their functionality. This radiation is non-conducting, meaning that the signal is not conducted through the metal or other material. When the signal travels a long distance, its propagation is in the form of a wave. The wave is dominated by the radiation field at a far distance, while the induction field dominates at near-surface distances. Non-ionizing radiation, on the other hand, does not ionize the gases and does not affect electronic devices. Examples of non-ionizing radiation include RF, microwave ovens, infrared, and visible light.

Static electricity is another EMI source. Although it is difficult to identify the source of this noise, it can originate from natural sources such as lightning. In addition to affecting the performance of electronic devices, EMI can also cause safety problems in many systems. The most common cause of EMI is electrostatic discharge. Non-technical people recognize this type of noise as radio static, distorted television reception, and clicks in audio systems.

EMI degradation after filling with water

EMI degradation after filling with water after power supply switching can be classified into two types: radiation and conduction. The EMI degradation after filling with water is usually induced by changes in the temperature of the input ground and the conductive material used to make the water-filled capacitor. The conductive material includes aluminum and copper fibers, which have the highest intrinsic electrical conductivity. However, the surface of these fibers is prone to oxidation, which can affect the conductivity of the components. Moreover, some unscrupulous merchants might not provide consistent products.

EMI can affect the safety and performance of electrical appliances. These unwanted signals can interfere with radio communications and cause malfunction in nearby equipment. Hence, EMI shielding is an essential requirement for electronic devices. Various methods and materials are used for EMI shielding. Listed below are some of them:

Continuous carbon fiber composites exhibit better EMI SE and are better conductive than their discontinuous counterparts. A continuous carbon fiber composite with a carbon matrix exhibits a EMI SE of 124 dB. On the other hand, discontinuous carbon fibers significantly reduce the SE of the composites.

Switching power supplies have improved over linear regulators in terms of efficiency, but they still introduce discontinuous currents which can negatively affect the reliability of the system. EMI analysis is easier to perform for conductive noise than for radiated noise. The conductive noise can be evaluated using standard circuit analysis techniques.

EMI degradation after filling with ethanol

Electromagnetic interference (EMI) can affect electronic components and devices in many ways. For example, if a capacitor is subjected to a voltage peak that is higher than its nominal voltage, it can suffer diolectric degradation. This degeneration can result in malfunction or burn, depending on the component’s characteristic.

Electromagnetic interference is a common problem in modern technology. It causes malfunctions of electronic devices and may lead to damage to communication systems. This interference is caused by a variety of sources, including sparks from motor brushes, power circuit switches, inductive and resistive loads, relays, and circuit breaks. Even the slightest amount of EMI can degrade the performance of an electronic device and impair its safety. The most common source of EMI is electrostatic discharge (ESD), which many people recognize as static on radio stations, distorted television reception, and clicks in audio systems.

EMI can also be generated by switching power supplies. These power supplies are strong sources of EMI and require careful control. It is crucial to quantify the output noise of these power supplies to reduce the risk of EMI. This is a time-consuming and expensive process.

Sådan bruger du et par modstande til at forbedre nøjagtigheden af et multimeter

For at forbedre nøjagtigheden af dit multimeter kan du bruge et par modstande og komponenter. De skal holdes på plads, så de forbliver i kontakt med multimeterets sonder. Du må ikke røre modstandene eller komponenterne med hænderne, da dette vil resultere i unøjagtige aflæsninger. For at undgå dette problem kan du fastgøre komponenterne på et breadboard eller bruge alligatorklemmer til at holde dem på plads.

Brug af shuntmodstande

Modstandsværdien af en shuntmodstand udtrykkes i mikroOhms. Modstanden for en shuntmodstand er normalt meget lille. Ved at bruge denne type modstand forbedres multimeterets nøjagtighed, fordi den ikke introducerer uønskede virkninger fra ledningsmodstanden. Det er dog vigtigt at bruge den med en Kelvin-forbindelse, fordi shuntmodstandens modstand har tendens til at glide med den omgivende temperatur.

Multimetre er følsomme over for belastningsspænding, så operatørerne skal være opmærksomme på belastningsspænding og opløsning. Uregelmæssig testning kan resultere i uventede produktfejl. Shuntmodstande forbedrer multimeterets nøjagtighed ved at give ekstra opløsning. Dette er især nyttigt for bænkmultimeter, som er i stand til at foretage målinger i fuld skala.

Indstilling af det korrekte område på et analogt multimeter

For at indstille det korrekte område på et analogt multimeter skal du starte med at indstille ohm-enheden til den laveste værdi. Generelt skal modstandsaflæsningen ligge mellem 860 og 880 ohm. Alternativt kan du bruge det lavere modstandsområde på 200 ohm til indlæring og øvelse.

Et multimeter med manuel måling har en drejeknap med mange valgmuligheder. Disse er normalt markeret med metriske præfikser. Multimetre med automatisk rækkevidde er derimod automatisk indstillet til det relevante område. Desuden har de en særlig "Logik"-testfunktion til måling af digitale kredsløb. Til denne funktion tilslutter man den røde ledning (+) til anoden og den sorte ledning (-) til katoden.

Det kan virke skræmmende at indstille området på et analogt multimeter, især hvis du aldrig har brugt et før. Denne opgave er imidlertid overraskende enkel og kan udføres med et par modstande. Så længe du er opmærksom på de forskellige intervaller, vil du få mere succes med denne opgave.

Brug af præcisionsstrømaftastningsmodstande

Nøjagtigheden af et multimeter kan forbedres ved at bruge præcisionsstrømsaftastningsmodstande. Disse komponenter kan købes i forskellige udgaver. De er nyttige til anvendelser, hvor det er nødvendigt at have den korrekte mængde strøm, der kommer ind og ud af et batteri. De er også nyttige til anvendelser, hvor temperaturfølsomhed er et problem.

Det optimale fodaftryk er C, med en forventet målefejl på 1%. De anbefalede dimensioner for fodaftryk er vist i figur 6. Følerens sporføring spiller også en vigtig rolle for målepræcisionen. Den højeste nøjagtighed opnås, når følespændingen måles ved modstandens kant.

En strømaftagende modstand er en modstand med lav værdi, der registrerer strømmen og omdanner den til en spænding. Den har normalt en meget lav modstand og minimerer derfor strømtab og spændingsfald. Dens modstandsværdi er normalt på milliohmskalaen. Denne type modstand svarer til almindelige elektriske modstande, men er designet til at måle strømmen i realtid.

Berøring af modstanden eller sonden med fingrene

Multimetre har også en særlig funktion, der registrerer de positive og negative ledninger på et batteri eller en strømforsyning. Ved at holde multimeterets sonde mod ledningen i et par sekunder kan du afgøre, om den strøm, der strømmer gennem den, er positiv eller negativ. Den røde sonde er forbundet til den positive batteripol eller ledning.

Når du bruger et multimeter til at måle modstanden, skal du sikre dig, at kredsløbet ikke er tændt. Ellers kan du få en unøjagtig måling. Husk, at modstanden ikke er så vigtig som at vide, hvordan den skal måles. Desuden kan den strøm, der løber i kredsløbet, beskadige multimeteret.

Test af kontinuitet mellem huller på et breadboard

Før du måler modstanden mellem hullerne på et breadboard, bør du først kontrollere breadboardets tilslutningsmuligheder. Testmetoden er kendt som kontinuitetskontrol og er en enkel måde at afgøre, om to forbindelser er kompatible. Brødkortet har huller med en metalfjederklemme under hvert hul. Tilslut proberne på dit multimeter til begge disse punkter. Hvis du har problemer med at finde en ledende vej mellem disse punkter, kan du sætte et par modstande på mellem brødbrættet og multimeteret.

Hvis du bruger et multimeter med en programmerbar funktion, kan du gøre det mere præcist ved at teste kontinuiteten mellem nogle få huller ad gangen. For at gøre dette skal du indsætte proberne i "+" og "-" kolonnerne på breadboardet og derefter måle modstanden på tværs af dem. Hvis modstanden er uendelig, så er de to rækker ikke forbundet.