Wat is het verschil tussen SMD en NSMD?

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Wat is het verschil tussen SMD en NSMD?

SMD and NSMD are two types of semiconductors. While their pads are similar in size, NSMD components have smaller dimensions. In contrast, SMDs can be moved by the soldering iron, while a through-hole component can be mechanically secured prior to soldering.

NSMD pads are smaller

There are several differences between NSMD pads and SMD pads. Firstly, the solder mask for NSMD pads is made much smaller. This allows for the pad edge to leave a small gap that is not present on SMD pads. The following figure shows a top and cross-section view of an NSMD-style pad.

NSMD pads are smaller than SMD pads and are therefore more suitable for high density board layouts. They also allow more space between adjacent pads and allow easier trace routing. As a result, NSMD pads are used in high-density BGA chips. However, NSMD pads are more susceptible to delamination, but standard manufacturing practices should prevent this problem.

In addition to being smaller, NSMD pads are cheaper to manufacture. This is due to the fact that they are made of less expensive materials. However, this does not mean that they are of inferior quality. Whether you choose NSMD or SMD will depend on your application. For example, a board with large pads will need a solder mask that has a larger solder mask aperture than one with small pads.

When it comes to manufacturing BGA components, proper pad design is crucial. NSMD pads are smaller because they have solder mask apertures that are smaller than the copper pad diameter. NSMD pads also have a risk of asymmetrical solder bump, which will tilt the device on the PCB.

NSMD pads are used for diodes

NSMD pads are a kind of diode-packaging pads that differ from SMD pads in one important way: a gap is left between the pad edge and solder mask. Using a NSMD-style pad can result in improved solder connections and package pads with wider trace widths.

The solder lands on a PCB are either solder-mask defined or non-solder mask defined. The non-solder-mask defined pad is characterized by a gap between the solder mask and the circular contact pad. Solder flows over the top and sides of the contact pad to create a high-quality solder joint.

The diameter of an NSMD pad is often smaller than the diameter of a BGA pad. This reduced size allows easier trace routing. However, NSMD pads can be more prone to delamination than SMD pads. As a result, it is necessary to adhere to standard manufacturing practices to minimize the possibility of pad delamination.

When soldering BGA components, the pad design plays a crucial role. A bad pad can lead to poor manufacturability and costly hours of failure analysis. Fortunately, there are simple guidelines for pad design. With a little practice, you can make the correct NSMD pads for your BGA components.

NSMD pads are used for transistors

When using NSMD pads for transistors, you must remember that a NSMD pad is smaller than a corresponding SMD pad. This difference is due to the fact that the NSMD pads have a larger opening for the solder mask to fit. This allows for greater surface area for solder joints, a wider trace width, and increased flexibility in through-holes. However, this difference also means that an NSMD pad is more likely to fall off during the soldering process.

The diameter of a copper pad is a key factor in defining the size of an NSMD pad. NSMD pads are approximately 20% smaller than a solder ball, allowing for better trace routing. This reduction is necessary for high-density BGA chips. However, a NSMD pad is more prone to delamination, but standard manufacturing practices should minimize this problem.

NSMD pads are a good option when soldering transistors. These types of pads are often used in applications where transistors must be soldered through a hole in a metal substrate. This makes the soldering process easier and less time-consuming. However, the downside of using a NSMD pad is that you can’t get the same level of control over the soldering process as with a SMD pad.

The other major advantage of using SMD pads is that they can be easily manufactured. This method is very popular for manufacturing electronic components, as it is the most cost-effective way to create a high-quality board. Furthermore, the SMD approach is also a good way to minimize the number of variables that are involved in your design.

De meest voorkomende PCB-defecten en hun oplossingen

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De meest voorkomende PCB-defecten en hun oplossingen

There are many problems with PCBs, but some of them are less obvious than others. These problems are called implementation failures and require specialized knowledge to diagnose. For example, Electrostatic discharge, Chemical leakage, Lifted pads, and component shifting are all possible causes of failure. To identify the failure modes, a PCB must be stress tested until it fails.

Elektrostatische ontlading

Electrostatic discharge (ESD) is a common problem in electronic circuits. It results from the wrong handling of electronic components or an excessive voltage level. In many cases, the resulting damage is latent or catastrophic. This problem can cause a PCB to malfunction partially or completely.

There are several ways to detect and repair electrostatic discharge. While some of these are visible and will affect the performance of the product, others will not. The first method is to inspect the device to determine if any component is affected. In some cases, a minuscule hole will appear on the circuit board.

Chemical leakage

Chemical leakage in PCBs can be a problem for many industries. Although the United States banned the production of PCBs in 1977, they are still found in the environment at very low levels. Environmental cycling is the primary source of ambient PCBs, and they are transported throughout ecosystems. Although these contaminants have low levels, they can have serious effects on humans and the environment.

In addition to their use in electronics, PCBs were also used in the construction of school buildings during the 1950s to 1970s. Many schools had PCB-containing caulk and fluorescent light fixtures. The problem with these products was that they leaked, causing contamination in other building materials and the soil. This caused widespread contamination, which is why they were banned.

Lifted pads

Lifted pads are caused by a number of causes, including excess heat and force during soldering. The result can be an unsatisfactory solder joint. These defects require re-soldering, and can lead to short circuit hazards. Other causes of lifted pads include pollutant contamination, poor cleaning, or insufficient flux. Lifted pads can affect the functioning of circuits and the appearance of the board.

Lifted pads occur most frequently on thin copper layers and boards that lack through-plating. Identifying the root cause of a lift is crucial for preventing further damage. In the case of single-sided circuit boards, the problem is often the result of improper wave soldering. The lift can be prevented by using extreme caution while handling PCBs and avoiding excessive force when handling components.

Component shifting

Component shifting is one of the most common defects encountered in PCB assembly. It can be caused by a number of factors, including the placement of components incorrectly. For example, a component placed in a way that is not oriented correctly may float, resulting in a realignment of the component.

In some cases, the cause of component shifting is due to mismatching of the parts to the pad geometry. This causes the component to move towards the thermal mass closest to it. Other causes include bent leads, improperly placed components, or oxidation. Fortunately, there are a number of solutions to component shifting. For instance, adhering to the correct reflow profile, reducing movement during the unreflowed assembly process, and using an aggressive flux can all help minimize component movement.

Soldering ball defects

Soldering ball defects are common in the SMT assembly process. They are essentially balls of solder that separate from the main body of the solder. To prevent them, you should adjust the mounting pressure on the chip mounter to a precise setting. This will prevent the solder paste from being squeezed out of the pad and increase the chance that the solder paste will be generated properly.

A good solder joint will be clean, symmetrical, and have a concave shape. On the other hand, a bad solder joint may be large and have a long stem. Another common defect is disturbed joints, which will have a flaky, distorted, or uneven appearance.

Thermal imaging

Thermal imaging is a powerful tool for quality control, speeding up PCB and component repairs. By identifying hot spots, thermal images can point out faulty components or areas that are using too much power. This information can help designers reduce power consumption and prolong battery life. Thermal imaging can also detect areas that have poor thermal management, requiring more cooling, larger heat sinks, or even redesign.

Thermal imaging for PCB defects can also help designers and engineers determine the cause of defects. When a test board fails to pass quality control tests, a thermal imager can reveal the problems. It can also show the differences in temperature between two different areas of a board, revealing how the two differ.

5 factoren die de kwaliteit van SMT-solderen beïnvloeden

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5 factoren die de kwaliteit van SMT-solderen beïnvloeden

Several factors impact the quality of SMT soldering. These include equipment state, Solder paste quality and Stability. Understanding these factors will help you improve your SMT soldering processes. The best way to improve the quality of SMT soldering is to implement improvements in every area.

Stability

In a manufacturing process where components are placed on a PCB, the stability of the solder joints is important to the performance of the circuit. However, in certain conditions, the soldering process can be unstable. In these conditions, lead-free SnAgCu soldering paste is used to reduce thermal stress on the substrate. This type of solder paste has an advantage over other materials: it can be used on various substrates and can be applied by dispensing the paste onto the device surface.

A good solder paste will be stable to a specified temperature. The best way to check the stability of your solder paste is to use a viscometer to measure its viscosity. A good paste should be between 160 Pa*S and 200 Pa*S.

Repeatability

During the soldering process, the flux is a key ingredient for the successful soldering process. If the flux is insufficient or there are too many impurities, the soldering process can fail. The best way to ensure the repeatability of SMTS soldering is to carefully prepare components and PCB pads before soldering. It is also important to properly maintain the temperature of the reflow and to avoid any movement of the assembly during reflow. Lastly, the alloy must be analysed for any contaminants.

While lead-free solders are recommended, leaded solder can be used in certain cases. However, it is important to note that leaded solder does not have the flux needed to make reliable joints. As a result, the soldering process is not repeatable.

Equipment state

Many factors affect the quality of SMT soldering. These factors include the design of PCB pads, the quality of the solder paste, and the state of equipment used for manufacturing. Each of these factors is fundamental for reflow soldering quality insurance. Moreover, they can also influence soldering defects. To improve soldering quality, it is essential to use excellent PCB pad designs.

In addition to the selection of components, the mounting precision is another factor affecting the quality of the solder joint. The equipment used for mounting must have high precision so that the components remain stable. In addition, the mounting angle should be correct to ensure that the polar device is correctly oriented. Also, the thickness of the component after mounting must be appropriate.

Solder paste quality

Soldering defects can be the result of a variety of factors. Often, these problems are caused by improper PCB design. Incorrect pad design can result in components that shift or tombstone-shape, as well as soldering defects. For this reason, the design of PCB pads should be carefully scrutinized to avoid these problems.

Temperature and humidity play a significant role in the quality of solder paste. An ideal temperature for application is around 20 degrees Celsius and the right humidity is between thirty to fifty percent. High moisture levels can cause balls to form, which affects the soldering process. Scraping blade speed and quality are also important factors that affect soldering. For optimal results, solder paste should be applied starting from the core and move towards the edges of the board.

Speed, scraper pressure, stencil descending speed, and stencil cleaning mode should all be optimized for maximum solder paste printing. Improper speed can result in uneven solder paste printing and may reduce production efficiency. Another critical parameter is stencil cleaning frequency. Too high or too low stencil cleaning speed can cause a buildup of tin, which can affect production efficiency.

PCB design

PCB design is a critical aspect of manufacturing quality. It involves the proper positioning of components on the board to ensure that they are mounted correctly. It should include enough clearance for mechanical fixing holes. Otherwise, the delicate components can be damaged. In addition, solder joints near the footprints of surface mount components may result in shorts. Hence, it is essential that the PCB design allows for the proper placement of both conventional and surface mount components.

In addition to the correct placement of components, the proper PCB design can also contribute to SMT soldering. According to HP statistics, about 70 to 80 percent of manufacturing faults are caused by defects in the PCB design. The factors that affect the design of the PCB include component layout, thermal pad design, component package types, and assembly method. The PCB design must also consider electromagnetic compatibility (EMC) points and via positions.

Hoe PCB-materiaal met hoge thermische geleidbaarheid het probleem van warmteafvoer oplost

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Hoe PCB-materiaal met hoge thermische geleidbaarheid het probleem van warmteafvoer oplost

PCB's, ook bekend als printed circuit boards, zijn gelaagde structuren gemaakt van koperfolies ingeklemd tussen glas-epoxylagen. Deze lagen dienen als mechanische en elektrische ondersteuning voor componenten. De koperfolie met hoge geleidbaarheid dient als geleidend circuit in de PCB, terwijl de glas-epoxylaag dient als niet-geleidend substraat.

Printplaatmateriaal met hoge thermische geleidbaarheid

Thermische geleidbaarheid is het vermogen van een materiaal om warmte af te voeren van een apparaat. Hoe lager de thermische geleidbaarheid, hoe minder efficiënt het apparaat is. Materialen met een hoge thermische geleidbaarheid maken vias overbodig en zorgen voor een gelijkmatigere temperatuurverdeling. Dit vermindert ook het risico van gelokaliseerde volumetrische expansie, wat kan leiden tot hotspots in de buurt van componenten met een hoge stroomsterkte.

Een typische PCB voor een personal computer kan bestaan uit twee koperen vlakken en twee buitenste sporenlagen. De dikte is ongeveer 70 um en het warmtegeleidingsvermogen is 17,4 W/mK. Het resultaat is dat de typische PCB geen efficiënte warmtegeleider is.

Koperen munten

Koperen muntjes zijn kleine stukjes koper die in de printplaat zijn ingebed. Ze worden onder de component geplaatst die de meeste warmte produceert. Dankzij hun hoge thermische geleidbaarheid kunnen ze de warmte van de hete component afvoeren naar een koellichaam. Ze kunnen in verschillende vormen en maten worden gemaakt om op de gewenste plaatsen te passen en kunnen worden gemetalliseerd om een strakke verbinding te garanderen.

Glas-epoxy

Het probleem van warmteafvoer wordt steeds belangrijker in elektronica. Overmatige warmte kan leiden tot onderpresteren en vroegtijdig falen. Momenteel zijn de mogelijkheden voor warmteafvoer beperkt, vooral in extreme omgevingen. Een van de oplossingen voor dit probleem is het gebruik van glasepoxy PCB-materiaal voor hoge temperaturen, of HDI-PCB. Dit materiaal kan dit probleem oplossen doordat het een warmtegeleiding heeft die meer dan tweehonderd keer beter is dan FR4 composiet.

De glasexpoxyhars heeft een uitstekende hitte- en vlambestendigheid. Het heeft een hoge glasovergangstemperatuur en een hoog warmtegeleidingsvermogen. Het kan dienen als isolatielaag en warmtedissipatielaag. Het kan worden gemaakt door impregnatie of coating. De thermische geleidbaarheid van glas epoxy PCB verbetert de prestaties en stabiliteit van elektronische componenten.

PCB's met metalen kern

Fabrikanten van PCB's met metalen kern hebben nieuwe boardsubstraten geïntroduceerd die bestand zijn tegen hoge temperaturen. Hierdoor kunnen ze selectief dikkere koperlagen met een hogere thermische geleidbaarheid aanbrengen. Dit type PCB zorgt voor een betere warmteafvoer en kan worden gebruikt voor fijne circuitpatronen en chipverpakking met hoge dichtheid.

Naast een hogere thermische geleidbaarheid zijn metalen printplaten ook vormvast. Aluminium printplaten met metalen kern hebben een grootteverandering van 2,5-3% bij verhitting, waardoor ze ideaal zijn voor toepassingen met een hoog vermogen. Hun lage thermische uitzetting maakt ze ook geschikt voor hoge schakelvermogens. Het meest gebruikte metaal voor een PCB met metalen kern is aluminium, dat goedkoop en recycleerbaar is. De hoge thermische geleidbaarheid zorgt voor een snel afkoelingsproces.

Een ander probleem in verband met warmteafvoer is het risico van overmatige warmte. De warmte die wordt gegenereerd door warmteproducerende componenten moet van de printplaat worden afgevoerd, anders zal de printplaat niet optimaal presteren. Gelukkig zijn er nu nieuwe mogelijkheden om dit probleem op te lossen. PCB's met een metalen kern met hoge thermische geleidbaarheid zijn een nieuw soort thermische oplossing die deze problemen kunnen overwinnen.

FR4 substraten

PCB's zijn gelaagde structuren gemaakt van koperfolies en glasversterkte polymeren. Ze ondersteunen en verbinden elektronische componenten. Het koper creëert een geleidend circuit binnenin de PCB, terwijl de glas-epoxy laag fungeert als een niet-geleidend substraat.

Componenten met een hoog vermogen kunnen het beste in het midden van de print worden geplaatst en niet aan de randen. De reden hiervoor is dat warmte zich ophoopt bij de randen en naar buiten verspreidt. Ook moet de warmte van krachtige componenten ver weg van gevoelige apparaten worden geplaatst en moet de warmte door de printplaat worden geleid.

PCB-materiaal met een hoge thermische geleidbaarheid is de beste oplossing voor warmteafvoer, waardoor warmte snel wordt afgevoerd en warmteophoping wordt voorkomen. High-tech PCB's gebruiken koper, aluminium of keramiek als substraatmateriaal. Dit lost de problemen met warmteafvoer op en maakt de PCB's duurzamer.