PCB surface finish
In the whole manufacturing process of PCB, surface finish is a coating between a component and a bare board PCB. It is applied for two basic reasons: to ensure solderability, and to protect exposed copper circuitry. As there are many types of surface finishes, selecting the right one is no easy task, especially as surface mounts have become more complex and regulations. In this passage we will talk about the surface finish knowledge and if you are curious about this topic, then read our content below.If you want to order PCB product, please check and custom your order online.What are the types of surface finish of PCB? Though many types of PCB surface finishes exist, we’ll be covering three well-known ones here — HASL, OSP and ENIG. What is HASL ? A HASL surface finish offers high-quality solderability and accommodates multiple thermal cycles while also being one of the more affordable options. It once served as the industry standard, although standards under the Restriction of Hazardous Substances (RoHS) have caused HASL to fall out of compliance. In turn, lead-free HASL has become the more acceptable option in terms of its environmental and health impacts. Although HASL has a long industry history and is well-known among engineers, lead-free HASL is safer to use and better fits the needs of directives like RoHS. HASL finishes are created by dipping the board into a tin and lead or tin and nickel solder and holding it there for some time. Once the PCB is removed, hot bursts of air called air knives remove the excess finish. HASL finishing allows for a large processing window, but various factors can affect its evenness and therefore its solderability. The angle of the air knives, the air pressure and the speed of the PCB board’s entry and removal from the solder all influence the finish’s quality. You’ll find HAL and lead-free HASL surface finishes used for applications such as: Electrical testing: HASL finishes provide automatic protection for the test pads and vias during electrical testing of the circuit boards.Hand soldering: HASL finishes are a suitable option for hand soldering processes, as the joints are easily formable.High-performance electronics: HASL is often a great choice for high-performance and high-reliability applications, like aerospace and military devices, because of its ability to form strong joints. What is OSP? An OSP surface finish is an example of an organic PCB finish. There are no toxins involved in the process, making it environmentally friendly while still retaining its protective and anti-corrosive properties. Because of the absence of harmful chemicals, OSP boards are also RoHS compliant. This water-based finish provides a flat surface for attaching additional PCB components, and like the HASL process, it is cost-effective. OSP can be used as an effective replacement for lead-free HASL due to its co-planarity. When you need a PCB surface finish that will provide sufficient flatness while offering a simple manufacturing process, OSP is arguably the best choice. Applying an OSP surface finish to a PCB usually involves a conveyorized chemical method or a vertical dip tank. The process generally looks like this, with rinses between each step: Cleaning: The copper surface of the PCB is cleaned of oil, fingerprints and other contaminants that could affect the flatness of the applied finish.Topography enhancement: The exposed copper surface undergoes micro-etching to increase the bond between the board and the OSP. This process also reduces oxidation. To achieve adequate film thickness, the micro-etching must be kept at a consistent speed.Acid rinse: The PCB undergoes an acid rinse in a sulfuric acid solution.OSP application: At this point in the process, the OSP solution is applied to the PCB.Deionization rinse: The OSP solution is infused with ions to allow for easy elimination during soldering. This rinse should be used before preservatives build to avoid tarnishing from the presence of other ions in the OSP solution.Dry: After the OSP finish is applied, the PCB must be dried.OSP offers a simple and affordable process, but it’s also important to keep in mind that it’s extremely sensitive to handling and can easily retain scratches, which can degrade its solderability. Additionally, its shelf life is shorter than that of ENIG or HASL. Common uses for OSP include: Fine pitch devices: This finish is best to apply to fine pitch devices because of the lack of co-planar pads or uneven surfaces.Server boards: OSP’s uses range from low-end applications to high-frequency server boards. This wide variation in usability makes it suitable for numerous applications. It’s also often used for selective finishing.Surface mount technology (SMT): OSP works well for SMT assembly, for when you need to attach a component directly to a PCB’s surface. What is ENIG? Despite the higher pricing of ENIG surface finishing, it has a high success rate for producing high-quality products. It holds up under multiple thermal cycles, showcases great solderability and is a suitable option for wire bonding. As the name suggests, it consists of two coating layers — nickel and gold. The nickel protects the base copper layer and enables secure attachment of electrical components, while the gold serves as an anti-corrosion measure for the nickel. ENIG can be used in situations where tight tolerances are required for PCB elements like plated holes, as HASL is not as effective for this. Like OSP, it offers excellent flatness and is ideal for fine pitch devices. Applying the ENIG coating requires nickel to be deposited onto a copper surface catalyzed with palladium. The immersion gold stage causes the gold to adhere to the nickel by way of a molecular exchange. ENIG is similar to OSP in its inclusion of micro-etching and rinsing between each stage — the process includes these steps: Cleaning.Micro-etching.Pre-dipping.Applying the activator.Post-dipping.Applying the electroless nickel.Applying the immersion gold.Standard applications for an ENIG surface finish include: Complex surface components: Because of its flat surface, this finish type is a preferable choice for complex PCB components requiring smooth surfaces, like ball grid arrays (BGAs) or quad flat packages (QFPs). Wire bonding: ENIG finishes allow for minimal wire bonding for aluminum wires, although they are not compatible with gold. High reliability applications: You will often find ENIG surface finishes used for PCBs in industries such as aerospace, military, medical and high-end consumer. Its quality makes it suitable for applications where precision and durability are vital.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 05/15/2021 17:41
PCB solder mask
Solder mask is a thin layer of polymer that is put on a circuit board to protect the copper from oxidation and shorts during operation. It also protects the PCB from environmental influences such as dust and several other contaminants that may lead to shorts in the long run. Solder mask or solder stop mask or solder resist is a thin lacquer-like layer of polymer that is usually applied to the copper traces of a printed circuit board (PCB) for protection against oxidation and to prevent solder bridges from forming between closely spaced solder pads. A solder bridge is an unintended electrical connection between two conductors by means of a small blob of solder. PCBs use solder masks to prevent this from happening. Solder mask is not always used for hand soldered assemblies, but is essential for mass-produced boards that are soldered automatically using reflow or solder bath techniques. Once applied, openings must be made in the solder mask wherever components are soldered, which is accomplished using photolithography.Solder mask is traditionally green but is now available in many colors.If you want to order PCB product, please check and custom your order online.What are main types of PCB solder mask? Top and bottom side masks These are typically used by engineers to identify openings in the green solder mask, already applied on the PCB. This particular layer of solder mask is added through epoxy or film methods. Next, the component pins are soldered to the board utilizing the openings that have been registered using the masks. The traces on the top-side of the board are called top traces and the corresponding solder mask used is called a top-side mask. Identical to the top-side mask, the bottom mask is used for the bottom side of the board. Epoxy liquid solder masks The most cost-effective option among solder masks is epoxy. It is a polymer that is silkscreened on the PCB. Silkscreening refers to a printing technique that uses a woven mesh to support ink-blocking patterns. The mesh enables the open areas to be identified for the process of ink transfer. This step is then followed by thermal curing. Liquid photoimageable (LPI) solder masks LPI solder masks are actually a mix of two distinct liquids. These liquids are kept separately and mixed right before the application of the mask layer to enable longer shelf life. LPI is also one of the more cost-effective options among various other types. LPI is employed for curtain coat, screen printing, and spray applications. This mask is a blend of various polymers and solvents. A thin coating can be formed using this mask that can stick to the target area surface. After using this mask, the PCB will generally not require any final surface finish that is currently available. Unlike conventional epoxy inks, LPI is sensitive to UV light. The panel is required to be covered with the mask and after a short ‘tack cure cycle’, the PCB is exposed to UV light using a UV laser or photolithography process. Before mask application, the panels are subjected to cleaning and are checked for any sign of oxidation. This is done using a chemical solution, aluminum oxide solution, or using suspended pumice to scrub the panels. One of the most popular techniques used to expose the panel surface to UV light is through the use of film tools and contact printers. The top and bottom sheets of the film are printed using emulsion to block areas that need to be soldered. Production panels and film are then fixed in position, making use of tooling on the printer and exposed to a UV light source simultaneously. One method utilizes direct imaging that makes use of a laser. This technique does not need tooling or film as the laser is controlled through the use of fiducial markers placed on the copper template of the panel. LPI masks are available in various colors such as green, black, red, yellow, white, and blue. Dry film photoimageable solder masks The use of dry film photoimageable solder masks requires vacuum lamination. This dry film is subjected to exposure and then developed. Post-development, openings are identified to generate a pattern, after which the components are soldered to the copper pads. High-density wiring boards benefit most from dry film solder masks as it does not flood the through-holes. How the solder masks influence PCB? Now that we have delved into the solder mask process, let’s examine how this process affects your PCB. As previously stated, the solder mask impacts PCB assembly and board quality. The most notable impacts of solder mask are listed below: Prevention of solder bridges Provides a solder dam between solder joints and other conductive areas of the board where Solder bridges may form, potentially leading to short circuits or board damage.Reduction of solder paste consumptionAllow less solder paste to be used during solder process.Additional insulation of the components from PCBServe as an insulator between board components. Protection of the PCB Guard against contaminants that may be introduced from handling the board.Prevents oxidation that may shorten the operational lifetime of the device.Increasing the breakdown voltageMay increase the breakdown voltage of the board’s dielectric material.Prevention of metal whiskersHelp prevent the growth of tin whiskers mostly associated with lead-free solder or tin-plating for electronic components.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 05/14/2021 18:00
PCB prototypes are early samples of products built with the sole purpose of testing design ideas to see if they work. Although most prototypes, in general, are made to test basic user functionality, engineers require somewhat, if not entirely, functional PCB prototypes to check the complete functionality of designs. Different types of PCB prototypes are used to test different aspects of the design. Over the course of a project, a design team may use multiple PCBs at various stages of the design process. Some of these prototype types include: If you want to order PCB product, please check and custom your order online. Visual modelsVisual models are used to illustrate the physical aspects of the PCB design and show the overall shape and component structure. These are usually the first prototypes in the design process, and they are used to communicate and review the design in a way that is easy and affordable. Proof-of-concept prototypeProof-of-concept prototypes are simple prototypes that focus on replicating the primary function of the board without carrying all of the capabilities of the final product. This kind of prototype is primarily meant to show that the design concept is viable. Working prototypeWorking prototypes are functioning boards that contain all of the planned features and functions of the final product. These are usually tested to identify weaknesses or problems in the design and rarely represent what the finished product is going to look like. Functional prototypeFunctional prototypes are meant to be as close to the final product as possible, providing the most accurate idea of what the design will look like and how it will work, with some basic material differences to keep prototyping costs low. Why is prototyping important? PCB designers use prototype PCBs throughout the design process, repeatedly testing the functionality of their solution with every new addition or change. While it may seem like prototypes add several steps and costs to the process, prototypes serve important functions in the design process. Reduced TimelineEngineers will go through several iterations before creating the final product. While this can create lengthy timelines, PCB prototypes can help speed up the design and manufacturing process as a whole through the following means: Complete testing: PCB prototypes enable design teams to test designs and spot problems quickly and accurately, taking the guesswork out of the equation.Visual assistance: providing prototypes as visual aids can help communicate the design more easily. This helps minimize time spent on explanations and client-requested redesigns.Minimized rework: Prototype testing allows you to see and test the board before a full production run. Manufacturing Review and AssistanceWhen using a third party PCB prototyping service, companies can benefit from the assistance of a new set of eyes. Several things can go wrong in the design process that result in mistakes, including: Excessive input: In the design process, customer and team changes can build up and overlap to the point where the design is unrecognizable compared to its first iteration. Eventually, the designers may simply lose track of design best practices in the rush to meet client demands.Design blind spots: While a designer may create fantastic PCBs of one specific type, they may have less experience in another area and subsequently create a small problem in the design.DRC: DRCs can verify that a return path to ground exists, but may not determine the best trace geometry, size and length to get the best results from that path. Accurate, Reliable PrototypeHaving an accurate, reliable PCB prototype makes it much easier to solve design issues throughout the development process. Quality PCB prototypes accurately represent the functionality of your final product: PCB design: Prototyping enables designers to catch flaws early in the development process, and the more accurate the design. Functional testing: What works in theory doesn’t always work in practice. Accurate PCB boards will help assess the theoretical values of the board to see if they show up in the practical values. Conditional testing: It is essential that PCB products go through appropriate testing to ensure that they will survive environmental conditions. Final product design: PCBs are usually incorporated into a final product, and prototypes help determine if the planned product or packaging need to be adjusted for the final PCB design. Test Components IndividuallyThese prototype PCBs test single functions that are meant to be incorporated into a larger PCB, ensuring that they work as expected. This type of testing can be used for many purposes, including: Testing design theories: Simple PCB prototypes are used in proof-of-concept runs, allowing engineers to see and test a design idea before it goes further into the design process. Breaking down complex designs: Often, simple PCB prototypes break down the basic parts of a final PCB, ensuring that the design performs one basic function before moving on to the next.Reduced CostsStandard PCB production runs can get costly, and leaving things to chance can increase the bill. Prototypes are essential for reducing production costs. Catching design flaws: The sooner the development team catches a design flaw, the sooner it can be fixed and the less costly the fix is. The later on in the process the problem is caught, the more expensive the fix..With a high-quality Pinpointing cost-saving adjustments: Depending on the specific design of a PCB, there may be several options available for materials and components.Determining product adjustments: In some cases, adjustments to the PCB will result in the PCB taking on a slightly different shape or material than originally planned, which may affect the specifications and manufacturing needs of the product as a whole.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 05/11/2021 17:27
The flexible PCBs feature a combination of several printed circuits as well as components that are positioned on a flexible substrate. These circuit boards are also known as flex circuit boards, flex PCBs, flex circuits, or flexible printed circuits. These printed circuit boards are designed using the same components as rigid printed circuit boards. However, the only difference is the board is made such that it flexes to a desired shape during the application. Flexible PCB is continuously growing, with applications in the main electronics sectors, such as consumer, automotive, electro-medical devices, wearable, telecommunications and aerospace. The introduction of flexible PCBs has revolutionized the legacy electrical interconnection techniques, traditionally used to connect multiple parts of the same circuit or of multiple electronic devices. Thanks to the flexible nature of the connection, its compactness, and the high density of electrical connections that can be achieved, the solution based on flexible PCBs allows to obtain a considerable reduction of space, weight and costs compared to an equivalent solution based on rigid PCBs. And today we will focus on the detailed knowledge of flexible PCB.If you want to order PCB product, please check and custom your order online. What materials are used in flexible PCB? There are single-sided, double-sided and multi-layered forms in flexible circuits, each of which requires a variety of materials to function. The materials that MCL works with include both custom and branded materials from trusted suppliers. A few of the materials you can choose from include these: AdhesivesThe requirements of an application, as well as the dimensions of the conductor involved, tend to guide adhesive selection. Some of the most popular adhesives on the market include acrylics, epoxies, pressure-sensitive adhesives (PSAs) and adhesive-free base materials. FinishesA few of the finishes you can choose from include carbon, gold, hard nickel, tin, silver and even organic materials. Each option creates different results and is best suited to different applications, so be sure to consult with MCL on the best finish for your needs. InsulatorsInsulators are a must, and you’ll need the right insulation material to match your PCB. The wrong insulator might result in PCB failure in the long term. PCB insulators combine coverlay materials and flexible substrates in a variety of form factors and thicknesses. What are the types of flexible of PCB? There are several types of flexible circuits that can be designed according to the needs of the customer. Given below are a few basic types: What is Single Sided Flex?It comprises a conductive layer of copper on one side of the PCB. Single sided circuit PCBs are ideal for dynamic applications, or equipment that require circuits with high levels of flexibility. They are known for their immense cost-effectiveness and ease of assembly. What is Double Sided Flex?An expansion on the singled sided flex PCB, the double sided flex comprises a conductive layer of copper on both sides of the PCB. Generally, the copper layers are connected to each other by Plate Through Holes (PTH) or vias. These holes or vias create an active circuitry between the layers. What is Multi-Layer Flex?As the name suggests, multi-layer flex circuits comprise more than two copper conductors. In a typical circuit, you will find up to 10 conductive layers. Like the double sided flex circuit boards, multi-layer PCBs are interconnected by PTH holes or Vias. What is Rigid Flex Circuit Boards?This circuit is a combination of rigid and flexible circuits. The flexible layers are integrated with the rigid layers, and the PCB is assembled using PTH technology. The advantage of this type of circuit is that the combination of rigid and flex layers creates small interconnect areas, which reduces the chances of PCB failure in an application. What is High Density Interconnects?Also known as HDI, high density interconnects are flex circuit boards, which are designed to provide more technical solutions in terms of design, layout, and construction. Each HDI includes extremely dense flex circuitry with precise features and microvias.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 05/10/2021 18:20
There are many components in the PCBs and it is necessary to understand all the parts and materials as repairing or assembling the printed circuit board. When we are talking about PCBs, trace is mainly in referring to the network of copper, wiring, insulation, as well as fuses that is made up of the board. In general, there is a high probability that the PCB trace is inconsistent if it has some wrong with any given electronic device. Besides, trace resistance is the most common term used by electronic engineers in the printed circuit board industry. As well as the trace resistance means the parts of a PCB that resist the flow of a current. PCB trace is a really essential part for each PCB like a current, and it will spend more time and energies on fitting if make it wrong to detect or calculate the trace. On the contrary, it may lead to making mistake in the system for any device.If you want to order PCB product, please check and custom your order online. What is PCB trace thickness? The thickness of a PCB board makes a great influence for a designer during the design process of a PCB board. The thickness holds essential gravity as by ignoring it the PCB board might not function or may result in damage or sparks which might also cause harm to the components connected to the board. For electronic designer, the thickness of PCB plays an important role in the PCB design. The thickness can keep the balance, however, there will not function or lead to damage for the circuit board, as well as involving the components connected to the board. Because single-sided, double-sided and multi-layered PCB boards exist in the market so does the thickness of these boards also varies with the type of PCB board. And there are some common PCB trace thickness ranging from 0.008 inches to 0.240 inches, such as 0.2 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.6 mm, 2.0 mm, 2.3 mm and so on. The significance of PCB thickness is equal if not less than that of a PCB board. The PCB thickness holds of immense importance. The designers perform a lot of complex calculations to reach the depth of PCB board that could deliver accurate results. In case of wrongly calculating the PCB trace thickness, this may result in either not gaining the accurate results that the PCB designed for or it may also result in damaging the components attached to the surface of the PCB board. Due to the accuracy of the PCB trace thickness material used during the design of PCBs is saved to avoid wasting or over-using. What is PCB trace width? There are several factors that drive trace width, length, and style during the PCB design process of the next PCB prototype. This article will dive into a variety of applications that demand specific trace layout characteristics and how to incorporate them into your PCB design. So we are talking about the basics. What exactly is trace width and why is specifying a particular trace width so important? The point of a PCB trace is to connect any kind of electrical signal, whether it is analog, digital, or power, from one junction to another. The junction can be the pin of a component, a branch off of a larger trace or plane, or an empty pad or test-point intended for probing. Trace widths are often measured in mils, or thousands of an inch. A standard trace width for an ordinary signal may be in the 7-12 mil range and be as long as a few inches, but there are many things that should be considered when defining the width and length of a trace. The application will often drive the trace widths and types in a PCB design and at a certain point, there is usually a balance with regards to PCB fabrication cost, board density/size, and performance. If a board has specific design requirements such as speed optimization, noise or coupling mitigation, or high current, the trace widths and types might be more important than optimizing for manufacturing cost of the bare PCB or overall board size. What is PCB trace spacing and length? For digital designs with high speed communication, specific spacing and tuned lengths may be required to minimize cross-talk, coupling, and reflections. Some common applications for this are USB-based serial differential signals, and RAM-based parallel differential signals. Generally, USB 2.0 will require differential pair routing at speeds of 480Mbit/s (USB high speed class) or higher. This is partly because high-speed USB generally operates at a much lower voltage and differential, bringing the overall signal level closer to the noise floor. There are three important things to consider when routing high speed USB lines: trace width, trace spacing, and trace length. And the most critical out of the three is making sure the two traces are matched as closely as possible in length. As a general rule of thumb, if the traces differ any more than 50 mils in length from each other, it significantly increases risk of reflections which could result in poor communication. 90 Ohm matched impedance is a common specification for differential pair routing and to achieve this, the traces should be optimized in width and spacing.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 05/06/2021 18:03
PCBs are very important in the whole PCB manufacturing process.But how to choose the best manufacturing board components? A lot are standardized off-the-shelf parts that you can fast identify, find, and purchase. You’ll achieve your PCB assembly process faster if you know the parts that you need. Printed circuit boards are essential in the manufacturing process of a circuit board. But how do you go about choosing the best manufacturing board components? While Electronic components process information in form of electrical signals, a Printed Circuit Board PCB is the skeletal structure on which the electronic components are mounted and soldered to hold them together and provide pathways for information to flow between components through PCB traces. Some of the most commonly used electronic components are resistors, capacitors, inductors, diodes, LEDs, transistors, crystals and oscillators, electromechanical components like relays and switches, ICs, and connectors. These components have terminals and are available in specific standardized packages that the designer can choose to suit his application. SMT (Surface Mount Technology) and Through-hole are the two types of mounting techniques used to place components on a PCB. If you want to order PCB product, please check and custom your order online. What are the types of PCB components? What is Resistor?Resistors are one of the most commonly used components in PCBs and is a passive electrical component whose function is to introduce resistance to the flow of electric current in an electrical circuit to limit the current. Their function is to resist the flow of current by dissipating electric power as heat. They come in a multitude of different types made of a range of different materials but the classic resistor most familiar to the hobbyist is the ‘axial’ style resistors with leads on both long ends and the body inscribed with colored rings. These rings are a code that indicates their resistance value. What is Capacitor?The Capacitor is a passive electrical component, whose function is to store electrical energy and deliver it to the circuit when needed. The function of capacitors is to temporarily hold electric charge, and release it whenever more power is needed elsewhere in the circuit. Typically, it does this by collecting opposite charges on two conductive layers separated by an insulating, or dielectric, material. Capacitors are often categorized according to the conductor or dielectric material, which gives rise to many types with varying characteristics from high capacitance electrolytic capacitors, diverse polymer capacitors to the more stable ceramic disc capacitors. Capacitors fall into two categories: Polarized and non-polarized. What is Inductor?The Inductors is a passive two-terminal electrical component that stores magnetic energy when an electric current is passed through it. It’s an insulated wire wound into a coil around a core of some material (air, iron, powdered iron, or ferrite material) in a spiral form. The simplest inductor is a coil of wire. The greater the number of windings, the greater the magnetic field and therefore inductance. This serves to amplify the magnetic field substantially and therefore, the stored energy. Inductors are often used to filter out or block certain signals, for example, blocking interference in radio equipment or used in conjunction with capacitors to manipulate AC signals in switched mode power supplies. What is Potentiometer?Potentiometers are a form of variable resistor. They are commonly available in rotary and linear types. By rotating the knob of a rotary potentiometer, resistance is varied as the slider contact is moved over a semi-circular resistor. The linear potentiometer is the same, except that resistance is varied by moving the slider contact on the resistor linearly. What is Transistor?Several billions may be found in a single IC chip. But transistors are simply amplifiers and electronic switches. They come in several types, with the bipolar transistor as the most common type. They can be further categorized into NPN and PNP versions. Bipolar transistors have 3 pins – the base, collector and emitter. For an NPN type, when a small current flows through from the base to the emitter, then it turns on another circuit that causes lager current to flow from the collector to the emitter. In a PNP transistor, the directions are reversed. What is Diode?The diode is two terminal semiconductor devices that allow an electric current to pass in one direction. It allows current to flow in one direction only, from the anode (+) to the cathode (-). It does this by having zero resistance in one direction and high resistance via the other direction. This feature can be used to block current from flowing in the wrong direction, which could cause damage. Typical material used in a diode is silicon and germanium. They conduct when a minimum forward voltage is applied across it and remain off during reverse bias condition. What is SCR?SCR is short for Silicon Controlled Rectifiers, also known as thyristors, are similar to transistors and diodes. Actually, they are essentially two transistors working together. They also have three leads but consist of four silicon layers instead of three and only function as switches, not amplifiers. Another important difference is that only a single pulse is required to activate the switch, whereas current has to be applied continuously in the case of a single transistor. They are more suited to switching larger amounts of power. What is IC?ICs, known as integrated circuits are exactly that, they are circuits and components that have been shrunk down onto wafers of semiconductor material. The sheer number of components that can be fit onto a single chip is what gave rise to the first calculators and now powerful computers from smart phones to supercomputers. They are usually the brains of a wider circuit. The circuit is typically encased in a black plastic housing which can come in all shapes and sizes and have visible contacts. What is Crystal Oscillator?Crystal oscillators provide the clock in many circuits that require precise and stable timing elements. They produce a periodic electronic signal by physically causing a piezoelectric material, the crystal, to oscillate, hence the name. Each crystal oscillator is designed to vibrate at a specific frequency and more stable, economical and have a small form factor compared to other timing methods. What is Switch and Relay?The switch is simply a power button to control the current flow in the circuit, by switching between an open or a closed circuit. Similarly, a relay is an electromagnetic switch operated via a solenoid, which becomes like a sort of temporary magnet when current flows through it. They function as switches and can also amplify small currents to larger currents. What is Sensor?Sensors are devices and the function is to detect changes in environmental conditions and generate an electrical signal corresponding to that change, which is sent to other electronic components in the circuit. Sensors convert energy from a physical phenomenon into electrical energy, and so they are in effect, transducers. They can be anything from a type of resistor in a resistance temperature detector (RTD), to LEDs detecting in-fared signals, such as in a television remote.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 05/06/2021 17:58
No matter what kind of printed circuit boards you’re building or what type of device they’re being used for, your PCBs need to function correctly. These boards are the keys to the performance of many products, and malfunctions can have serious consequences. Inspecting PCBs throughout the design, PCB manufacturing and PCB assembly processes is crucial to assuring that your product meets quality standards and operates as expected. Today, PCBs are complex. While this complexity makes room for lots of new capabilities, it also creates more chances for failures. As PCBs have gotten more advanced, so have the inspection techniques and technologies used to ensure their quality. You can choose from various methods of PCB inspection. The right technique to use depends on the PCB type, the current step in the production process and the faults for which you want to test. Creating an adequate inspection and testing plan is crucial for ensuring a high-quality product.If you want to order PCB product, please check and custom your order online. Why do PCB need inspections? Inspection is a critical step in any PCB production process. It can help you to catch defects so that you can correct them and improve your overall operation. Inspecting your PCBs can uncover any defects that may have occurred during manufacturing or assembly. It can also help to reveal any design flaws that may exist. Checking PCBs after each phase of the process enables you to catch flaws before moving on to the next stage, which can save you from wasting further time and money on a defective product. It can also help you catch one-off defects that affect one or several PCBs. This process helps to ensure consistent quality among your boards and final products. Without a proper PCB inspection procedure in place, flawed boards may make it into the hands of customers. If a customer receives a faulty product, your company may lose money through warranty payments or returns. The customer will also lose some of the trust they had in your company, and your reputation will suffer. This situation can result in missed opportunities if that customer takes their business elsewhere. How to do PCB inspection? What is Manual Visual Inspection?The simplest form of PCB inspection is manual visual inspection (MVI). To perform this type of test, a worker looks over the board either with the naked eye or through magnification. They’ll compare the board to the design documents to ensure that all specifications were met. They’ll also look for common defaults. The type of defects they look for vary depending on the kind of board they’re checking and the components on it. Ensure that the board’s thickness is correct, and check for surface roughness and warpage. Check the dimensions of the assembly match the specification. Inspect the integrity and clearness of conductive patterns, and check for solder bridging, open circuits, burrs and voids. Check the surface quality, then look for the existence of pits, dents, scratches, pinholes and other defects on printing traces and pads. Verify that all vias are in the correct positions. Inspect the firmness, roughness and brightness of pad plating, and check for any bulge defects. Assess coating quality. It’s simplicity and low-cost. You don’t need any specialized equipment except potentially for magnification. You can also conduct these inspections very quickly. What is Automated Optical Inspection?You can also use a PCB inspection machine to conduct a visual inspection. This method is called automated optical inspection (AOI). An AOI system conducts an inspection using several light sources and one or more still or video cameras. The light sources light up the board from various angles. The cameras then take still images or video of the board, compiling them to create a complete picture of the unit. The system then compares the images it captures with information about what the board should look like taken from design specifications or an approved completed unit. AOI is a well-established, accurate technology and can detect many well-known faults in PCBs. It’s useful at many stages of the PCB production process. It’s also faster than MVI and eliminates the possibility of human error. Like MVI, it can’t be used to inspect components that are out of the line of sight, such as connections that are hidden underneath ball grid arrays and other types of packaging. It might also not be effective for PCBs that have a high concentration of components because some of them may be hidden or shadowed. What is Automatic Laser Test Measurement?Another option for PCB inspection is automatic laser test (ALT) measurement. You can use ALT to measure the dimensions of solder joints and solder joint deposition as well as the reflectivity of various components. An ALT system uses lasers to scan PCB assemblies and take measurements. As the light reflects from the board’s components, the system uses the position of the light to determine their height. It also measures the intensity of the reflected beam to determine the component’s reflectivity. The system can then compare these measurements to design specifications or to a board that has been approved as accurate to identify any defects. Using an ALT system is ideal for determining the quantity and position of solder paste deposition, and it provides information about the alignment, viscosity, cleanliness and other attributes of solder paste printing. What is X-Ray Inspection?With the rise of surface mount technology, PCBs have become more complex. Boards can now be more densely populated, feature smaller components and include chip packages such as BGAs and chip scale packages (CSPs) through which you cannot see hidden solder connections. These features present challenges for visual inspections such as MVI and AOI. X-ray inspection is ideal for more complex boards and offers some capabilities that other inspection methods do not, such as the ability to see through chip packages. It also works well for inspecting densely packed PCBs and allows for a more detailed inspection of solder joints. The technology is a bit newer and more complex, and it can be more expensive. It might only make sense to invest in x-ray inspection equipment if you have a high volume of densely populated boards with BGAs, CSPs and other such packages.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/30/2021 18:10
Within a printed circuit board electronics assembly, production or manufacturing process there are a number of individual stages. Each stage of assembly and production must be compatible with the next, and there must be feedback from the output to the input to ensure that the highest quality is maintained. In this way any problems are detected quickly and the process can be adjusted accordingly. A PCB with components mounted on is called an assembled PCB and the manufacturing process is called PCB assembly or PCBA for short. The copper lines on bare board, called traces, electrically link connectors and components to each other. They run signals between these features, allowing the circuit board to function in a specifically designed way. These functions range from the simple to the complex, and yet the size of PCBs can be smaller than a thumbnail. And how PCBs are assembled? The PCB assembly process is a simple one, consisting of several automated and manual steps. With each step of the process, a board manufacturer has both manual and automated options from which to choose. To help you better understand the whole PCBA process in detail, we will provide you each step in detail below.If you want to order PCB product, please check and custom your order online. The PCB assembly process What is solder paste stenciling?The first step of PCB assembly is applying a solder paste to the board. Stencil，manufactured from metal or polymer, is applied with solder paste to all of the pads on the bare-board. This process is typically referred as solder paste stenciling. Stencil is used for solder paste stenciling process that consists of a bunch of holes and resembles to the SMD footprint pads on bare-board layout. The stencil is placed over the boards and a layer of solder paste is squeegee over it. This leaves a nice and uniform layer of solder on the SMD pads. The primary function of solder paste stenciling includes binding, connecting and cleaning. What is pick and place?Development of pick and place systems are directly related to the growing importance of surface mount technology. These systems have become an important aspect of PCB assembly line. Pick and place systems offer automated, faster and highly efficient solutions during the assembly process. They place components automatically on the PCBs. Traditionally, this was a manual process done. These days this step is an automated process among PCB manufacturer in order to the relatively faster operational rate and minimum errors. What is reflow soldering?Reflow soldering has gained significant attention over the past few years, particularly for its use in attaching surface mount components to printed circuit boards. Reflow soldering is primarily used to form the required solder joints. This process is carried out by pre-heating the components and solder paste, and melting the solder without causing damage. Once the solder paste and surface mount components are all in place. This means the solder paste needs to solidify, adhering components to the board. PCB assembly accomplishes this through a process called "reflow". What is deionized water cleaning of assembled boards?Deionized water is used for the cleaning of PCBs before they leave the shop floor. Whenever a board is made or revamped, there is a substance called flux that is residue on the board. And this flux buildup winds up clingy after several months, can turn out to be marginally acidic prompting a debilitating of solder joints which will cause corrosion and longevity issues. To clean the boards after assembly, we place the batches into a high-temperature, high-pressure equipment, all stainless-steel device. Any other metal would quickly disintegrate. What is inspection and quality control?In PCB assembly, quality control is very important at every stage. Further, inspection and quality control are performed by our industry experts in several different stages including visual inspection, structural inspection and automatic inspection. These technologies improve performance and offer overall defect coverage. Optical inspection, laser triangle measurement, X-ray inspection and X-ray lamination technology are some of the major technologies used in automatic inspection. Each of these technologies offers distinct benefits over another. What is through-Hole component insertion？A through-hole component is commonly identified as a device that is soldered with a wire or a metallic lead and mounted to the board. These components are placed with the help of the lead on plated holes of the board. Soldering is performed after placing these components on the respective plated holes. Critical factors to be considered include quality of the solder joint and the connection. Strong mechanical bonds make through-hole component insertion technique superior to the SMT technique. Other advantages include reduced available routing area for signal traces on layers and cost-efficiency. Limited routing space for signal traces on layers are available for all lower layer on multilayer boards as holes pass through all layers on the opposite side. What is mechanical customized insertion?The need for customization of mechanical components has risen over the past few years. Different types of mechanical components include wires, heat-sinks, spacers and stand-offs, screws, and connectors. The effective adoption of customized insertion solutions involving various mechanical components will ensure performance enhancement for PCBs. In addition, edge mount connectors and linear connectors also require customized insertion during PCB assembly. The use of turret solder for press mount terminal, which requires specialized tooling like swage tools, is also part of mechanical components. What is conformal coating?Conformal coating is typically used for protecting circuit boards from harsh environmental conditions, including moisture and chemical contaminants. The conformal coating is applied on PCBs and acts as a protective chemical coating or polymer film with a 25-75µm thickness. Conformal coating also helps to maintain long-term surface insulation resistance (SIR), thereby ensuring the operationality of the assembly. What is final Inspection and functional test?TFCT, also known as functional testing, is carried out during the last phase of the PCB assembly line. After the soldering step of the PCBA process is finished, a final inspection will test the PCB for its functionality. This inspection is known as a "functional test". The test puts the PCB through its paces, simulating the normal circumstances in which the PCB will operate. Testing is the final and most important step in PCB assembly process, as it determines the success or failure of the process. This testing is also the reason why regular testing and inspection throughout the assembly process is so important.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/29/2021 18:01
Plating on a PCB refers to the electrochemical process by which a metal is deposited onto the surface of the circuit board, and inside the plated through-holes. The most common plated metal in PCB fabrication is copper. Copper plating serves two purposes, it increases the copper thickness of the surface pads and conductors as well as providing a robust copper connection from layer to layer through the plated through-holes. The PCB construction process is the implementation of a well-defined paradigm wherein each step has its specific time or place to be performed. In order to understand this ordering of operations, it is important to know how each step is completed and its overall importance for your board development. The plating of your board’s surface traces and vias is an example of a situation where an understanding of its purpose enables you to make decisions that aid your contract manufacturer in building the best board for your design. Before discussing the surface PCB plating process options available to you, let’s clearly define what PCB plating is.If you want to order PCB product, please check and custom your order online. What are the PCB plating materials? Via PlatingVia plating has only one material known to everyone which is copper. Surface finishingThere are 4 materials in surface finishing which are Gold, Nickel, Tin, and Silver. The type of PCB surface finish materials you use matters a lot. It’s because there are loads of merits and demerits for each material. So, you need to check them out and weigh your options. Generally, you need also to consider the various types of PCB finishes you use for your PCB fabrication. So, it would help if you chose them based on their various features. That’s why we’d be talking about the different PCB finishes type in the next section. What is the PCB plating process? As we have seen, printed circuit boards are fabricated with copper features for electrical connectivity. Although the traces and area fills will usually be covered and protected with a solder mask, the pads and holes must be left out in the open for soldering. This exposure will pose a problem because copper left unprotected for any length of time will begin to oxidize and deteriorate, making the circuit board unusable. For this reason, a surface finish is applied or plated onto the exposed copper for its protection. Different types of surface finishes can be used on a circuit board depending on what kind of protection the board needs: HASLUp until recently, HASL (Hot Air Solder Leveling) has been the most widely used surface finish in the industry. The circuit board would be dipped into a molten pool of solder and then run through hot blasts of air to remove the excess. HASL is a low-cost operation available almost anywhere. It has a long shelf life and is easy to use. The downside of HASL is that it leaves uneven surfaces that can cause solder bridging and are not detailed enough for fine pitch components. ENIG ENIG (Electroless Nickel Immersion Gold) has become one of the most popular surface finishes currently being applied to circuit boards. It is composed of two layers of metal coatings, with the first being a layer of nickel that is chemically plated to the board. The nickel provides a barrier of protection for the copper and then, in turn, is protected from oxidation by a thin layer of gold. ENIG has excellent surface planarity making it ideal for soldering fine pitch components. It complies with the Restriction of Hazardous Substances requirements and is durable with a long shelf life. On the other hand, it is more expensive than other finishes, such as HASL. Immersion AGThis finish is often used in high-speed circuit boards as the silver has low losses in high-frequency applications. Immersion silver is deposited onto the copper using a chemical process and has excellent surface planarity for fine pitch parts’ solderability. Immersion silver is also RoHS compliant. The downside is that this finish is sensitive to contaminants in the air or on the board and must be kept in protective packaging to prevent it from becoming tarnished. Even with special packaging, its shelf life is roughly 12 months and must be used quickly after air exposure. ElectrodesThis process, which does not require electricity, may be used with immersion to create a metallic barrier. The process uses a catalyst to dissolve a copper rod. The copper is then distributed on the surface. OrganicSimilar to immersion, this process is considered eco-friendly, since no metal-to-metal contact is necessary. However, the shelf-life is short; therefore, good PCB storage guidelines would need to be in place. There are many other types of surface finishes in the PCB plating process, including; lead-free HASL, immersion tin, organic solderability preservative, and electroless nickel electroless palladium immersion gold, and hard gold. While these all have their uses, HASL, ENIG, and immersion silver are the most commonly used surface finishes for circuit boards.Wanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/29/2021 17:44
PCB manufacturing process
PCB is one of the important components in the electronic industry. Recent years, various CAD printed circuit board application software has been popularized and promoted in the industry, in the specialized PCB manufacturers, mechanization, automation production has completely replaced the manual operation. Printed circuit board has good product consistency, it can adopt standardized design, is conducive to the mechanization and automation in the production process. At the same time, the whole printed circuit board after assembly and debugging can be used as an independent spare part to facilitate the exchange and maintenance of the whole machine products. At present, printed circuit board has been extremely widely used in the production of electronic products. The manufacturing process of a PCB is pretty extensive. Whether you a PCB manufacturer or others, steps are crucial to the development of the board. Because each step is so critical to the process, let’s take a close look at the manufacturing process of a PCB. And we are talking about the manufacturing process in the content below. If you want to order PCB product, please check and custom your order online. PCB manufacturing process steps Design and OutputBefore you begin manufacturing the PCB, you need to have a design of the board. These blueprints will be what you base the process off of. The design process is generally completed through computer software. Using a trace width calculator will help with a majority of the details needed for inner and external PCB layers. Printing the Inner LayersThe design is printed to a laminate, the body of the structure. A photo-sensitive film made from photo-reactive chemicals that will harden when exposed to ultraviolet light overs the structure.. This will help align the blueprints and the actual print of the board. Holes are drilled into the PCB to help with the alignment process. Removing Unwanted CopperNow, it is time to remove any unwanted copper that remained on the board. A chemical solution, similar to the alkaline solution, eats away at the unwanted copper. The hardened photoresist remains intact. InspectionThe newly-cleaned layers will need to be inspected for alignment. The holes drilled earlier help align the inner and outer layers. An optical punch machine drills a pin through the holes to keep the layers lined up. After the optical punch, another machine will inspect the board to ensure there are no defects. From here on out, you will not be able to correct any missed errors. Laminating the LayersNow, you will see the board take shape as the layers are fused together. Metal clamps hold the layers together as the laminating process begins. A prepreg layer goes on the alignment basin. Then, a layer of substrate goes over the prepreg followed by a copper foil layer and more prepreg resin. Lastly, there is on more copper layer applied, which is the press plate. Pressing the LayersA mechanical press is then used to press the layers together. Pins are punch through the layers to keep them properly aligned and secured, these pins can be removed depending on the technology. If correct, the PCB will go to the laminating press, which applies heat and pressure to the layers. The epoxy melts inside of the prepreg that, along with the pressure, fuses the layers together. DrillingHoles are drilled into the layers by a computer-guided drill to expose the substrate and inner panels. Any remaining copper after this step is removed. PlatingThe board is now ready to be plated. A chemical solution fuses all of the layers together. The board is then thoroughly cleaned by another series of chemicals. These chemicals also coat the panel with a thin copper layer, which will seep into the drilled holes. Outer Layer ImagingNext, a layer of photoresist, similar to Step 3, is applied to the outside layer before being sent for imaging. Ultraviolet light hardens the photoresist. Any undesired photoresist is removed. EtchingThe same chemical solution from before removes any unwanted copper under the resist layer. The tin guard layer protects the needed copper. This step established the PCB’s connections. Solder Mask ApplicationAll of the panels should be cleaned before the solder mask is applied. An epoxy is applied with the solder mask film. The solder mask applies the green color you typically see on a PCB. Any unwanted solder mask is removed with ultraviolet light, while the wanted solder mask is baked on to the board. Silk screeningSilk screening is a vital step since this process is what prints critical information onto the board. Once applied, the PCB passes through one last coating and curing process. Surface FinishThe PCB is plated with either a solderable finish, depending on the requirements, which will increase the quality/bond of the solder. TestingBefore the PCB is considered complete, a technician will perform an electrical test on the board. This will confirm the PCB functions and follows the original blueprint designs. AssemblyIn assembly the bare board is populated with electronic components to form a functional printed circuit assembly (PCA), sometimes called a PCBA. In through-hole technology, the component leads are inserted in holes surrounded by conductive pads; the holes keep the components in place. In both through hole and surface mount, the components are then soldered; once cooled and solidified, the solder holds the components in place permanently and electrically connects them to the board. Protection and packagingPCBs intended for extreme environments often have a conformal coating, which is applied by dipping or spraying after the components have been soldered. The coat prevents corrosion and leakage currents or shorting due to condensation. The earliest conformal coats were wax; modern conformal coats are usually dips of dilute solutions of silicone rubber, polyurethane, acrylic, or epoxy. Another technique for applying a conformal coating is for plastic to be sputtered onto the PCB in a vacuum chamber. The chief disadvantage of conformal coatings is that servicing of the board is rendered extremely difficultWanna know PCB knowledge? Check and read for more.
PCB Glossary ⋅ 04/28/2021 17:54
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