BOM for PCB

How to Make a BOM for PCB

Creating a Detailed BOM for Efficient PCB Development

BOM is a detailed document that the designer must provide to the manufacturer with information on the materials and components utilized for a specific PCB design.

Let’s understand this by imagining that you need a dress. You go to the designer and tell him you need golden buttons from ABC brand, laces in LMN’s design and color, threads in XYZ brand in certain colors, and fabric (size, color, and manufacturer). For all the choices you made for the essentials of your design if you have their links, you share those links to be more specific and accurate. You can ultimately help a tailor or designer to create the dress of your dreams by using the design and its measurements together you provided with the choice of all the accessories and fabric.

Similar to this, when you give a manufacturer Gerber files for a PCB design, you also give them a BOM file or bill of materials file. Manufacturers can purchase and assemble components with the necessary orientations on pcb taking into account BOM files.

What is BOM?

A detailed description of every part and material needed to create and assemble a printed circuit board is contained in the bill of materials, or BOM, for the PCB. It plays an important role in PCB fabrication, procurement, and assembly. Based on this specified BOM, the manufacturer, and assembler can create the required PCB, therefore it must be detail-oriented while yet extremely precise.

BOM for PCB

Who creates and manages a BOM?

The Art of Managing BOM: A Story of Collaboration and Innovation

Depending on the organizational culture, different organizations adhere to different hierarchies. Usually, a team of professionals involved in the product development process creates a Bill of Materials (BOM) for a Printed Circuit Board (PCB). Multiple stakeholders, including the following, must provide input for the design of a PCB BOM:

  1. Project managers oversee the full process of developing a product, including the BOM. They are responsible for delivering quality project on time, so quality, quantity and procurement of the components is very important for them.
  2. Electrical engineers design the circuit and select the required components in order to achieve the function that they want. In determining the ratings, values, types, tolerances, and quantities of components that should be used on the PCB, they are the vital part of BOM making.
  3. PCB designers are responsible for the layout of the PCB, including component placement, electrical routing, and taking into consideration of the board’s mechanical specs. They depend on the provided BOM to make sure that the selected components are mechanically fit set to the size of pcb and required system.
  4. Component engineers are in the role of identifying components that match to the required requirements for availability, cost, and reliability. They could give recommendations for component replacement and selection.
  5. Mechanical engineers could be involved in the design process if the PCB is a part of a larger mechanical assembly. They need BOM to understand the mechanical requirements and space constraints of the PCB.
  6. As a project develops, maintaining the BOM is typically the job of documentation specialists. Throughout the course of the product’s lifetime, they make sure the BOM is correct and up to date. After the BOM is created and completed by every aspect, the design department’s project manager will forward it to the manufacturing and purchasing department for further process.
  7. The procurement team is in responsible for identifying and procuring the parts listed in the BOM. In order to determine the specific part numbers, quantities, and vendors for each component, they rely on the BOM.
  8. Manufacturing engineers use the BOM to lay out the assembly process, which includes component placement, soldering procedures, and quality control methods. A flawless and free of mistakes assembly process is made possible by accurate BOM.
  9. Quality control department can look over the BOM to confirm that the correct parts were used throughout the PCB assembly process in the right amount. It can be referred to as a quality check list during the quality assurance process.

So, we can say that the development of a PCB BOM is a combine effort of various departments mentioned above. As per hierarchy of the organization the process may differ but these all are the stake holders of BOM. To create an accurate and useful BOM that supports the successful design, manufacture, and assembly of the PCB, good communication and cooperation between various stakeholders are important.

How to Create a Comprehensive BOM?

The following essential information for each component should be included in a thorough bill of materials (BOM) for a printed circuit board (PCB), although they may vary from project to project based on the specifications for PCB and PCBA assembly. Here are a few categories that should be in the BOM; you can add or remove them according to what you require.

Reference Designator: There must be unique identity across each component on Pcb or example U1, U2, U3 for ICs similarly R1, R2, R3 for resistors and C1, C2, C3 for resistors. Lable them same as you label in Pcb file and mention other categories along them.

Part Number: The component’s part number from the manufacturer. This knowledge is essential for locating and choosing the right component.

Manufacturer: the company that creates the component. This makes it easier to get parts from trustworthy vendors.

Value: The component’s electrical value or rating. For instance, the voltage and current ratings for other components, the capacitance value for a capacitor, or the resistance value for a resistor.

Package Type: The component’s actual packaging or footprint. Specifying this helps to ensure proper component placement and assembly because different components come in different package types.

Description: A brief overview of the component, which may also give further details about its features, functions, standards, tolerance ratings, operating voltages etc.

Quantity: The total number of parts needed to assemble a PCB. In order to prevent shortages or overages during production, make sure that this quantity is precise. It is very necessary to make it accurate for series production and cost estimation.

Component Location: This is very helpful for PCBs with many layers that are complex. It details the precise coordinates or location where each component should be placed.

Layer: Mention the layer on which particular layer, whether top or bottom it should be placed.

Placement method: A likewise specify the surface mount technology or placement method that will be used to attach each component to the board. Through-hole and surface mount technology (SMT) are among of these techniques.

Datasheet Links: Links to the technical documentation or datasheets for each component. By doing this, it is made sure that everyone involved with the BOM has access to precise specs.

Supporting files: You’ll generate files as you design your board, including CAD files, data sheets, schematics, and instructions that don’t fit within the BOM spreadsheet. When needed, you should attach these additional files and link them to the relevant BOM level and components.

Notes: Any additional details or special instructions pertaining to the component, such as suggested soldering methods, sources of alternative materials, and recommended soldering techniques.

Alternative part numbers: If any component is unique and its availability is less, then provide the alternative part number with same footprint otherwise pcb designer has to change foot pattern on pcb board.

Distributor: The distributor or manufacturer who are providing components to procure. For quality products it is very important to mention distributor.

List of manufacturers: A list of authorized suppliers or manufacturers for each component is provided under Approved Manufacturers. This might aid in guaranteeing dependability and consistency.

Cost: Including the price of each component is optional, however doing so could help in cost analysis and planning.

Availability: The component’s lifetime state is listed, showing whether it is active or it is approaching the end of its intended lifespan, or it is obsolete. This is critical for the product’s long-term planning and maintenance.

Lead time: Lead time is listed in the BOM in order to check how much time component will take to be there for planning production and keeping the track of inventory.

Revision History: This is very important to mention the revision history, when and how BOM modified along with dates and summary of modifications.

A complete and precise BOM must be done for optimal and quick PCB assembly, procuring, and maintaining. A successful and reliable end product is created by making sure that the right components are used, procured, and assembled on the PCB during production.

Additionally, Rush PCB Limited is offering model templates that may be filled using the data gathered and documented in detailed BOM together with other Geber files. To get in touch for model BOM template, please feel free to email or contact us.

Perfect PCB layout design

Beginner’s Guide to Creating a Perfect PCB layout design

Expert Tips for Perfect PCB Layout Design

There are several stages to making your project a reality. Getting a reliable fabrication and assembly supplier like Rush PCB Limited is essential. Still, the basics must also be perfect for making your end product cost-effective and error-free.

PCB layout design is the most basic and crucial step in product development. However, there are several ways to get the PCB layout done, the first is the do-it-yourself approach, which takes time and effort, and the second is to outsource the project completely to a contract manufacturer like Rush PCB Limited as a Full Turnkey project.

Perfect PCB layout design

In this blog post, we will share the top five tips by our design experts, which help create a perfect layout design for a beginner and improves manufacturability, functionality, and product reliability.

Expert Tip # 1: Always Plan Your Schematic Diagram

The circuit diagram or schematic is the graphical interference of the components, interconnections, and functions of the Printed Circuit Board. The schematic diagram can be made on design software which gives access to create, modify and export the schematic and BOM files in multiple formats. Usually schematic is provided in PDF or SCH format.

Below are steps that need to be taken to plan the schematic diagram efficiently:

  1. Doing component labeling at an early stage saves a lot of time in case changes require on the design.
  2. Assign pin marking and nets to all the components to ensure connectivity.
  3. Mentioning component values gives the design structure on the schematic diagram to your contract manufacturer.
  4. Assigning symbols and colors to each part makes the job easier at the time of production.

The steps as mentioned above are usually observed while doing DFM and DFA on the Gerber and BOM files. Such information gives a clear idea about your design, and potential issues can be solved during pre-production.

Expert Tip # 2: Adjustment Of Component Placement For Optimal Performance

There is no doubt that the PCB cannot operate without the components; the interconnectivity of components makes the PCB work. So using the PCB real estate wisely by following the below PCB layout design rules can help you optimize your PCB performance and make it cost-effective:

  1. If all the similar components are placed in the same direction, it helps the pick and place machine programmer run the process efficiently and may take less time to assemble all the boards.
  2. The placement of components must be on a single side of the board if the through-hole parts pins are on the opposite side. In this case, you can save some Non-Recurring Engineering (NRE) charges on your assemblies.
  3. Per the IPC component placement guidelines, all the surface mount devices (SMD) components must be placed on the same side to minimize the reflow process.
  4. As per the IPC component placement guidelines, all the through-hole (TH) parts must be placed on the top side, as it helps minimize the wave soldering process.
  5. As per the IPC component placement guidelines, the mixed component assembly must ensure that all the SMD and TH component must maintain a decent distance which helps in avoiding component collision.

Expert Tip # 3: Signal, Power & Ground Traces Placement

The distribution and placement of traces such as signal, power, ground, and plane greatly impact physical PCB. Following the expert tip below can help you make a perfect PCB design.

  1. Always balance copper on each layer. Distributing the planes equally on each layer, especially for the inner layer where there are copper planes, will help avoid warpage issues after production.
  2. The large impact of warpage is observed when ball grid arrays (BGAs) need to be assembled, but due to board bendability, the solder joints don’t get in contact with the copper pads. The only solution is to distribute the copper planes symmetrically and centered in the internal layer.

Expert Tip # 4: Minimize Your Trace Length and Width

The fabrication process gets complex when the trace width and spacing get tighter and shorter. Consider that in mind, below is expert advice that can help minimize your production cost.

  1. The power traces must have wide trace width and spacing, as they carry significant current to power up the ICs and transformers.
  2. Make a thumb rule for multi-layer PCBs that if the signal trace is routed horizontally on one side, route the opposite side trace vertically. It helps in identifying the connections at the time of rework.
  3. We recommend considering the current to determine different nets with different current values; low current traces must have minimum trace width of 5 mils to 10 mils. However, wider traces are suggested for traces carrying a current of more than 0.3A.

Expert Tip # 5: Verify Your Layout Against Your PCB Design Rules.

PCB Design Rules Checks (DRC) help in double and triple checking your work to make it error-free, even at the stage of completing the design; our experts recommend verifying the DRC checks before submitting it for production can help in reducing Design for Manufacturing (DFM) and Design for Assembly (DFA) issues at the pre-production stage.

After the assurance of error-free Gerber files or Design files, our experts advise checking the routing of all signal layers and performing a schematic review to ensure connectivity. Many design tools have features that can cross-check the layout and the schematics.

Conclusion:

As a beginner mentioned above, all the expert advice can help you avoid any DRC issues during PCB manufacturing and assembly. After getting your perfect PCB design, you must ensure all the files, including Gerber and ODB++, IPC netlist, BOM files, fabrication, and assembly drawings, must be submitted for a quick full turnkey quote. Rush PCB Limited aims to provide Full Turnkey quotations within 24 hours and offers the fastest Full Turnkey PCB service throughout the United Kingdom (UK), the Middle East, and Europe.

To learn more about our Full Turnkey PCB capabilities, fill out our contact form or call us at 0203 750 0201. We are happy to assist you anytime.

ENIG Surface Finish

ENIG Surface Finish

PCB manufacturers frequently use electroless nickel immersion gold (ENIG) plating because of its anticorrosion and uniform plating properties. A thin layer (0.05 to 0.23um) of gold is plated over a layer (4-7um) of nickel through a chemical process.

ADVANTAGES

  1. ENIG meets all the ROHS requirements, which makes it environmentally friendly.
  2. It ensures a flat surface of gold covering the pads, allowing for better soldering performance. Therefore it is best for fine-pitch components.
  3. Shelf life of ENIG surface finish is 12 months or more. So it offers a variety of project creations.
  4. ENIG finish boards can handle high-temperature.

ENIG Surface Finish

CONSIDERATIONS FOR ELECTROLESS NICKEL IMMERSION GOLD PLATING

The ability of ENIG plating to prevent oxidation and corrosion while enabling dependable soldering and bonding makes plating popular in the electronics industry. However, several things could reduce ENIG’s efficiency.

Nickel phosphorous occasionally develops while the electroless nickel plating procedure is being done. As a result, solder junctions become less reliable, potentially compromising performance.

The thickness of the gold layer must be considered. The maximum possible gold thickness is 5 inches or less since gold can start to corrode the nickel layer if it is kept in the bath for too long.

WHAT METALS ARE SUITABLE FOR ELECTROLESS NICKEL IMMERSION GOLD PLATING?

ENIG can cling to a variety of metal-based materials, such as:

  1. Copper
  2. Aluminum
  3. Steel
  4. Steel Stainless

 

WHY CONSIDER RUSH PCB FOR NICKEL IMMERSION GOLD PLATING?

At RUSH PCB Limited, we have years of expertise working with businesses in various demanding industries to provide complete-service finishing solutions. We take the time to comprehend the particular needs of your business and adjust our coating or finishing process as necessary. Please fill out our contact form immediately to get more information about the benefits of ENIG plating or a price.

DOUBLE-SIDED PCBS

How Double-sided Pcbs Are Changing The Electronics

Understanding Double-Sided PCBs: Benefits and Applications

What are Double-Sided PCBs?

The most common type of printed circuit boards (PCBs) used nowadays are double-sided PCBs. Higher technology electronics employ double-sided PCBs rather than single-sided ones since they have two-sided traces with a top and bottom layer.

A double-sided PCB can be visualized as two single-sided PCBs stacked on top of one another. When you put it this way, it makes sense, but there are just two layers on each side of a double-sided PCB, which makes them no more sophisticated than single-sided PCBs.

Because you can alternate between a top and bottom layer rather than just relying on one layer as you do with a single-sided PCB, there are closer and more routing traces accessible when your PCB is double-sided.

Copper and other components can be mounted on both sides of a double-sided PCB board, allowing the traces to cross over one another.

DOUBLE-SIDED PCBS

Benefits of Double-Sided PCBs

A double-sided PCB provides benefits that a single-sided PCB cannot. In your forthcoming project, employing double-sided PCBs has several benefits:

  • A double-sided PCB has twice as many component spaces as a single-sided PCB since it has conductive layers on both sides. Easily increase circuit complexity and density.
  • Double-sided PCBs are a cost-effective option for many popular electronics because of their circuit complexity. Create well-liked electronics for regular usage by using double-sided PCBs.
  • The size of a double-sided PCB is the same as a single-sided PCB, but it has twice as much component space. With the same amount of area, create more complex projects.
  • Double-sided PCBs are more affordable than multilayer PCBs and can be utilized for a wide range of tasks. Save money by only putting two layers instead of three.
  • You can significantly increase the group of projects that are within your budget and capabilities for a reasonably minimal fee. Create advances that a single-layer PCB would have prevented.

What is the Difference Between Single and Double-Sided PCBs Assembly?

These two PCBs are both commonly utilized in many kinds of electronics. PCBs are a crucial component of the electronic devices we use every day, from computers and cell phones to radio controls and other consumer electronics. However, single- and double-sided PCBs serve different purposes and require slightly different manufacturing processes.

Double-sided PCBs are typically utilized in more sophisticated technologies, while single-sided PCBs are employed in many various types of electronics. The type of PCB is decided by manufacturers based on demand, output, and cost.

Conductive metal and components are typically put on just one side of single-sided PCBs. The connection is made through the other side using conductive wiring, typically made of copper. PCBs with two sides require additional work. They have wiring running across both sides and electronic components located on both sides. Although tough to make, its benefits outweigh its drawbacks and labor-intensive manufacturing method.

Conclusion

In conclusion, both single-sided and double-sided printing are significant—but for different reasons. Since both boards were constructed in different ways, their purposes are distinct. Likewise, they are priced differently for the same purpose. A manufacturer may choose a single-sided or double-sided board depending on the application, cost, and other factors.

Contact Rush PCB if you’re unsure about the board you require; we’ll be pleased to discuss your needs with you, recommend the best course of action, and make sure you receive high-quality PCB boards.

 

PCB Gerber

How to Use PCB Gerber Files

PCB Gerber Files: Vital for Fabrication and Assembly

Rush PCB UK makes well-fabricated and well-assembled printed circuit boards for the electronics industry. The bottom line is that a high-quality PCB is a critical aspect of ensuring the operational soundness of electronic products. The fabrication process, however, relies on the design of the PCB, and the means of communicating these details is via the PCB Gerber file. It is the pivotal aspect ensuring the successful capture and actualization of the design of the PCB.

PCB Gerber Files

Companies providing electronic contract manufacturing and electronic manufacturing services often turn printed circuit board designs into high-quality and reliable boards. However, ECMs can carry out the fabrication and assembly process successfully only if they have the proper raw materials like copper clad, electronic components, solder, etc. But above all, however, they need the basic design guidelines that are available in the PCB Gerber file.

A PCB Gerber file is an open ASCII vector formatted file, comprising information on all the layers of the circuit board design. This includes all aspects of the circuit board traces, vias, pads, silkscreen, and solder mask images, which find representation in the file as a draw or flash code. Multiple vector coordinates further represent these objects. Ultimately, the PCB Gerber file is a pivotal point for PCB manufacturers for translating the design details into realistic properties of the circuit board.

That makes it essential for the PCB designer to coalesce all design details into their Gerber files properly. The information must offer accurate and understandable information, and it must do so following general standards. Typically, PCB design software suites generate the Gerber files in most instances. However, the generation process depends on the CAD tool under use. Presently, the PCB design file generation uses the RS-247X file format of the Gerber file, superseding other obsolete file formats such as the R-274-D Gerber. In addition, most Gerber data has file extensions such as .gb or .gbr for text files. Therefore, it is not necessary to assign a distinctive file name.

PCB Gerber

PCB Gerber Files for Manufacturing

Over the years, there has been substantial improvements in printed circuit board manufacturing technology. For instance, earlier, vector photo-plotters created tooling films for PCB fabrication. They used a concentrated beam of light, which exposed the film after passing through an aperture. It also formed flashes when drawing the traces and pads. Therefore, creating larger films with numerous line drawings took a long time.

Earlier, as the number and set of apertures in use were minimal, designers had to restrict the copper trace widths and features. Fortunately, vector machines have also evolved into newer types, deploying raster lasers for exposing the film. The laser photo-plotter now creates large films in no time at all.

Latest Gerber Files for PCBs

The latest laser plotters use Gerber information, but the earlier restrictions on apertures for vector plotters are now no longer in place. The laser plotter converts the coordinates in the Gerber file into a raster file, and the information instructs the plotter about what it must print and where to print it. For instance, the aperture definition conveys the size of pads and the width of traces. Similarly, a drawing command provides the information on the position of polygon fills with lines or flashes. The laser beam simply sweeps across the film while exposing the image in real time.

Recent developments have manufacturers bypassing the film creation process. Rather, they use the laser imaging to create images directly on the copper clad. This direct printing effectively bypasses the film creating stage. Nowadays, Gerber files use fresh database formats that comprise smart design data like net connectivity. However, the older formats are still in use, as some manufacturers still continue to use films.

Conclusion

According to Rush PCB UK, it is necessary to configure the Gerber file creator to ensure the setup of standards, formats, and units are consistent with the standards of the PCB manufacturer. Another important file, but separate from the Gerber file, is the drill file (NC). This file is necessary to direct the drilling equipment to the proper position during fabrication.

EMS PCBs

All About EMS PCBs

Rush PCB UK: Comprehensive Electronic Manufacturing Services

Rush PCB UK offers various types of printed circuit boards under EMS or Electronic Manufacturing Services. Under our electronic manufacturing services, we undertake the complete operations for manufacturing, assembling, testing, and repairing printed circuit boards and assemblies.

Electronics Manufacturing Services

Electronic manufacturing services involve many sectors, including healthcare, telecommunications, medical, automotive, etc.:

Commercial Electronics

The commercial electronics sector requires many services such as PCB assembly, cable assembly, prototyping, contract designing, repairing, and more.

Healthcare and Medical

Healthcare and medical electronic equipment require reliability and safety in complex circuitry. All this requires a reputed electronics manufacturing service provider to obtain cost-effective quality products.

Aerospace and Defense

The military and aerospace industry always require highly durable and reliable equipment. Most electronic equipment they use face hazardous situations and must continue to function without failure. Moreover, electronic products that go into ships, aircraft, and spacecraft must ensure high security, operational performance, and traceability. Only a reputed electronics manufacturing service provider can offer excellent electronic products for aerospace and defense.

EMS PCBs

Electronic Manufacturing Service Providers

It is necessary to consider many factors when deciding on an electronic manufacturer as a suitable service provider. Of course, it depends entirely on the requirements and personal choices. However, customers must ask the manufacturer a few questions to determine whether the company is the right one for them.

Number of Years in Service

This question establishes the amount of experience the company has in the desired field. Newcomers to the field may not be able to handle complex boards and may disrupt the total planning. The manufacturer must have considerable experience in the job.

Extent of EMS

It is essential to know beforehand the extent of coverage offered. In general terms, this is also known as after-sales service.

Even after extensive prototyping and assessments, there can be problems cropping up after delivery, and in the field. It helps if the service provider can take responsibility for such cases and provide the necessary support and attention.

Product Introduction Procedure

For introducing any new product in the market, it is necessary to maintain a proper introduction procedure. The electronic manufacturing service provider must be aware of such introduction procedures and provide full support.

Product Lifecycle Surveillance

The electronic manufacturing service provider must offer product lifecycle surveillance. This must include, apart from introduction, growth, maturity, and decline stages.

During the introduction phase, the quantity of products required is usually low. The numbers pick up during the growth phase and stabilize during the maturity phase. Once the decline phase sets in, the quantity requirements will again decline. The electronic manufacturing service must be willing to support the OEM through all the lifecycle phases of the product.

Services Offered

It is very important to know all the services the electronics manufacturing service provider offers. In general, any reputed electronics manufacturing service provider will offer a wide spread of services starting from designing to repairing products. Typically, they will do everything to develop a complete and compatible electronic device. EMS providers typically stand out from their competitors by providing quality products.

Common Services

Although all electronic manufacturing service providers are different, some of the services they offer are common. These include:

  • Prototyping
  • PCB Assembly
  • Cable Assembly
  • Electromechanical Assembly
  • Contract Design
  • Testing
  • After Sales Services

Prototyping and PCB assembly are the most valuable activities concerned with any electronic device. This can involve the design and development of a printed circuit board, the purchase of electronic components, and assembly. Oftentimes, it involves deciding whether the board will use through-hole components or surface mount components. It also requires deciding whether the board will be single-, double- or multi-layered.

Cable assembly and mechanical assembly require special expertise for their execution, as a major part of this activity is manual. Not only must the work done be accurate, it must be aesthetic and reliable. The process also involves the use of standard testing stages.

Conclusion

Rush PCB UK is a reputable electronic manufacturing service provider. Along with our regular services, we also offer circuit simulation and prototyping, 3-D CAD, body sculpting, various technological feasibility reviews, and integrity surveys. These are only some of the fundamental contract design services we offer. Please contact us for any further details.

SMD Boards

All About SMD Boards

Through Hole vs SMD Boards: Choosing the Right PCB Technology

All electronic equipment requires a printed circuit board to hold its electronic components in place. This board serves a dual purpose. Apart from providing a mechanical anchoring place for electronic components, the board also provides electrical connections to the components. This allows the components to interact with each other and function to let the electronic equipment perform as intended.

Types of Boards

OEMs use two typical boards for their equipment. One of the types uses through-hole components, while the other uses surface mount components. Rush PCB Ltd makes both types of boards of the highest quality.

Through Hole Boards

The use of through-hole components started earlier, and these components had long leads. Boards using these components must necessarily have multiple holes through which the leads pass for soldering on the other side.

If the boards are double-sided or multilayered, the holes are typically plated through. That means an electroplating process creates a thin barrel of copper on the wall of the hole. Additionally, the hole has two pads on the top and bottom surface to which the copper barrel connects. This creates an electrical connection from one side of the board to the other. When an operator passes a component lead through the hole and solders it, the solder wicks into the hole and anchors the component firmly.

Advantages of Through Hole Boards

Printed circuit boards using through-hole components have several advantages:

  • Easy to Assemble—As through-hole components are larger, it is easy to handle them manually. Thus, it is also easy to manually insert and assemble them on the board.
  • Easy to Repair—it is easy to solder and desolder boards with through-hole components.
  • Easy to Troubleshoot—It is easy to troubleshoot malfunctioning or non-functioning boards with through-hole components.

Disadvantage of through-hole Boards

  • Mechanically Weak—The presence of large numbers of holes makes a through-hole board much weaker.
  • Low Component Density— The larger size of through-hole components does not allow placing many of them on a unit area of the board.
  • Low Routing Density—For multilayer boards, the size increases as the presence of a larger number of holes reduces the routing density of copper traces.
  • Large Equipment Size—With low component density, the overall equipment size must also be large.

SMD Boards

SMD Boards

To reduce the size of electronic equipment, it is also necessary to reduce the size of their printed circuit boards. For this, OEMs tended to move to smaller electronic components such as SMD or Surface Mount Devices. In place of long leads, SMDs use small end caps, and therefore, SMD boards do not require through holes.

The printed circuit on SMD boards has pads matching the SMD footprints. Assembly of SMD boards requires placing small amounts of solder paste on the pads, followed by the SMD. Once the board passes through a reflow oven, the solder melts and anchors the components to the board.

Advantages of SMD Boards

SMD boards offer several advantages over through-hole boards. These are:

  • High Component Density—With SMDs being much smaller, and having no leads, it is easier to achieve a high component density. Many SMD ICs have pins on all four sides to offer high functionality in small sizes.
  • High Routing Density—The absence of through holes allows multi-layered boards to achieve high routing density. This helps to reduce the size of the board significantly.
  • Higher Mechanical Strength—The absence of through holes allows the SMD board to retain its mechanical strength. This allows it to withstand higher stress and vibrations without damage. As a consequence, the reliability of the equipment improves.
  • Smaller Equipment Size—With higher component density and smaller PCB size, SMD boards significantly reduce the form factor of electronic equipment.
  • Higher Functionality—With smaller components, designers can provide electronic equipment with higher functionality.

Disadvantages of SMD boards

Although SMD boards have many advantages, they also have some disadvantages:

  • Require Automated Assembly—Manual handling of very small SMDs is difficult and requires automated machines for placement and soldering during assembly.
  • Require Automated Inspection—Many SMDs have pins on the underside of their packages. Once soldered, the solder joints are neither visible nor accessible. Inspecting them requires automated machinery.
  • Difficult to Repair—Closely packed SMDs present a formidable challenge for troubleshooting and repair.

Conclusion

Although Rush PCB Ltd makes both through-hole boards and SMD boards, the popularity of the latter is significantly higher among customers. We have many varieties of SMD boards, including rigid, flexible, and rigid-flex types. Contact us for any type of board you require for your project.

PCB Sensors

All About PCB Sensors

PCB Sensors: Types, Mounting, and Performance

Rush PCB Ltd manufactures all types of printed circuit boards. Many circuit boards meant for industrial use typically have sensors mounted on them. Sensors are necessary to detect changes in ambient conditions. Sensors typically produce an electrical response corresponding to the changes in the environment. They transmit these signals to other elements on the circuit board, where the signals undergo processing. Such elements on the circuit board include passive elements like resistors, capacitors, and transformers, and active elements like transistors, diodes, and integrated circuits.

PCB Sensor Types

Industrial users require many types of PCB sensors. The most common among them are:

  • Flow and Level Sensors
  • Smoke and Gas Sensors
  • Touch Sensors
  • Proximity Sensors
  • Temperature Sensors
  • Sound Sensors
  • Strain and Weight Sensors
  • Color Sensors
  • Position Sensors
  • Humidity Sensors
  • Tilt and Angle Sensors
  • Magnetic Field Sensors
  • Accelerometer Sensors
  • PIR Sensors
  • Ultrasonic Sensors
  • Light Sensors
  • and more.

PCB Sensors

PCBs for Sensors

Most PCB sensors do not require any special type of board. However, some sensitive sensors may require surface cleanliness to avoid inaccurate measurements. Sensors working at high frequencies may require control impedance on the PCB. Guaranteeing good performance from a sensor on a board requires the PCB manufacturing process to follow the standard PCB manufacturing processes, including:

  • PCB Design
  • Gerber Creation
  • Inner Layer Creation
  • Via Drilling
  • Layer Etching
  • Inspection
  • Layer Stacking and Laminating
  • Plating
  • Solder Mask Application
  • Silk Screening
  • Surface Finish Application
  • Testing

Through-Hole Mounting for Sensors

Many sensors have long leads that require a through-hole mounting technique. That means, the PCB will have through-holes on it to allow the sensor leads to anchor. In the case of boards with more than one layer, the through-hole will be typically plated. A plated-through hole will have a thin copper barrel along its hole wall, creating an electrical connection from one layer to another.

The assembler must solder the leads after mounting the sensor properly in the through holes of the board. This anchors the sensor to the board while providing it with the necessary electrical connection to other components. Through-hole mounting sensors may be of the axial type or radial type.

Axial Lead Sensors

This type of sensor has a shape similar to that of a wire jumper. The leads protrude from opposing end points of the sensor, setting up an ideal geometrical axis of conformity. The axial lead sensor typically lies flat on the PCB surface after proper anchoring.

Radial Lead Sensors

In this type of sensor, the leads typically protrude from one side of the sensor. Therefore, after mounting, the sensor assumes an upright position on the board. Radial lead sensors are perfect for use on boards where there is a limited area of space.

Mounting Sensors

Mounting methods for sensors on monitoring locations significantly affect their performance. Broadly, there are four methods of mounting sensors on locations. These are:

  • Magnetic Mounting — using permanent magnets to mount the sensor, suitable for ferromagnetic materials only.
  • Stud Mounting — using studs to mount the sensor. This method provides the most secure and reliable attachment.
  • Adhesive Mounting — using adhesives to fix the sensor on the location.
  • Probe Tips or Stingers Mounting — this method is for sensitive sensors.

There are both advantages and disadvantages of each method of mounting. The user must consider them before deciding on the final technique. This requires considering characteristics such as the location of mounting, surface ruggedness, amplitude range required, accessibility, portability, ambient temperature, and more. Some characteristics can be extremely critical to the effective operation of the sensor. The mounting technique has the maximum effect on the high-frequency operation of the sensor.

Surface preparation is an extremely important step when mounting sensors. For most sensors, the surface must be as flat as possible, free of debris, and without any grease and oil. Some sensors work well if the surface has a light coating of a lubricant before mounting. The coating helps to improve the high-frequency response of the sensor. Users frequently use beeswax, heavy machine oil, or silicone vacuum grease for lubricating the mounting surface.

Conclusion

PCB sensors are an essential factor for consideration for Rush PCB Ltd. Whether the sensor is of the through-hole type or surface mount type, proper component placement is necessary to allow the sensor to perform at its highest capability. An accurate placement of the sensor is crucial for its reliable performance.

Types of PCB Holes

Types of PCB Holes

PCB Holes: Types and Functions by Rush PCB UK

PCBs made by Rush PCB UK may have many types of holes in them to meet different requirements. The PCB manufacturing process includes several processes such as cutting, grinding, filming, exposing, etching, developing, electroplating, laminating, drilling, surface treatments, solder masking, potting, etc. For a good quality PCB, the manufacturer maintains strict control of each of these processes. The drilling process makes many types of holes in a PCB, such as:

  • Through Holes
    • Plated Through Holes
    • Non-Plated Tool Holes
    • Plated Slotted Holes
    • Non-Plated Slotted Holes
  • Vias
    • Blind Vias
    • Buried Vias
  • Special Holes
    • Side-Stepped Holes
    • Countersunk Holes
    • Crimp Holes
    • Hole on Pads

Types of PCB Holes

Through Holes

Most printed circuit boards have through holes. These are holes passing through the entire thickness of the board. PCBs with more than two layers usually have a few plated through holes, some non-plated tool holes, and some plated and/or non-plated slotted holes. An electroplating process provides a thin conductive barrel from one end of the hole to the other, through the PCB.

Tool holes are mounting holes for aligning the board to a text fixture or a machine in its operating position. In general, a tool hole does not have any plating, which makes it non-conducting any electrical component or trace on the PCB.

The manufacturer provides tool holes on the periphery of the board, along a major axis. The second hole is typically a slotted hole, also non-plated. The board may have other slotted or through holes, plated and/or non-plated, for other mechanical/electrical requirements.

Apart from tool holes, a PCB may have many plated through holes for mounting through-hole components. The diameter of these plated-through holes is significantly smaller than tool holes.

Vias

Vias are holes necessary in the PCB for establishing electrical connections between PCB layers. They may be of two types–blind and buried.

Blind vias start from one of the two top surfaces of the board and end at an inner layer. They may electrically connect to more internal layers in between, depending on the design.

Buried vias start from one of the inner layers in the PCB, and electrically connect to one or more internal layers. They are not visible from outside the PCB.

As the function of vias is only to provide electrical connection between layers, their diameter is significantly smaller than those of tool holes and plated through holes. Additionally, vias are always plated through to provide electrical contact between the layers they interconnect. While a fabricator may drill a plated-through hole after assembling all the layers, they must drill via holes individually in the respective layer before assembling them.

Multilayer PCBs mostly use blind and buried vias, as they provide the maximum routing density. In most cases, where plated through holes cannot offer performance and manufacturing requirements, blind and buried vias help to break the density limitations in special designs such as those involving BGAs and fine-pitch components. Using blind and buried vias can help to reduce the size and number of layers required in a PCB. For very high density such as in HDI boards, fabricators may use lasers to drill tiny holes for vias.

To meet performance requirements, fabricators may cover the via opening with a solder mask or fill it with a conducting or non-conducting material. Tenting is the process of covering the via opening, and plugging is the process of filling the via hole.

Special Holes

These are holes for meeting various mechanical requirements of the PCB.

Conclusion

Older printed circuit boards had more plated through holes for mounting through-hole components. As there is greater demand for higher density boards, manufacturers have moved towards using surface mount components that do not require plated through holes. Moreover, higher density has led to the use of miniature vias drilled with lasers.

Standard for PCB Thickness

Newest Industry Standard for PCB Thickness

Choosing the Right Thickness for Your PCB: Insights from Rush PCB UK

Rush PCB UK makes various types of PCBs for the electronics industry. While determining the standard board thickness, the number of layers in a PCB is the key factor in deciding its actual thickness. As the number of layers in a PCB depends on its design and application, the thickness of the PCB will also vary according to its application. For instance, some applications will need a thicker board, while others may require a thinner one. However, the industry’s standard for the thickness of a PCB is 1.57 mm (0.063 inches).

PCB thickness typically refers to the thickness after the board is completed. This includes the thickness of tracks and pads, whether external to or internal to the layers. Primarily, two things directly influence the thickness of a PCB. These are:

Standard for PCB Thickness

Core Thickness

This is usually available in standard thicknesses of 0.5, 0.7, 0.8, 1.0, 1.2, 1.5, 1.6, 2.0, 2.4, 3.2, 6.4 mm.

Copper Cladding Thickness

This is generally available in standard thicknesses of 1 oz (35 µm), 2 oz (70 µm), 3 oz (105 µm)

A vast majority of circuit boards use the 1 oz (35 µm) thick copper foil. However, this mainly depends on the purpose of the PCB, and the current flowing through the traces. For PCBs that must carry higher amounts of current, some tracks may have 2 oz (70 µm) thickness or even 3 oz (105 µm) copper thickness.

Factors Affecting PCB Thickness

Three factors primarily affect multilayer PCB thickness:

PCB Core Thickness

The PCB core, also known as the dielectric or substrate, is the primary insulating material between two conductor layers. The core is copper-clad, and this remains unchanged in thickness during the PCB fabrication process.

Therefore, a two-layer printed circuit board will have a central core or substrate sandwiched between two copper foil layers.

The standard thickness of a substrate is usually 1.6 mm, for 2-, 4-, and 6-layer PCBs. As the number of layers increases, the board becomes thicker, as each layer adds a minimum thickness.

Prepreg Thickness

The layer structure of a printed circuit board may have 2 copper-clad cores separated with 2 to 3 prepregs. These are glass fiber fabric with resin impregnation. The fabrication process presses the prepreg layers with the cores.

While the cores do not change their thickness while undergoing pressing, the prepregs do change their effective thickness. The PCB manufacturer, therefore, decides the final thickness with the setting of their processes.

Internal PCB Layer Thickness

Apart from the sequencing of layers, the manufacturer actually customizes the stack-up with the internal PCB layer thickness. This is the vertical distance between the layers on which the copper tracks lie.

However, PCB manufacturers do not have complete freedom on adjusting the internal thicknesses. In reality, these thicknesses depend on the specific construction sequence the manufacturer decides for the printed circuit board. They may decide to use a certain structure to achieve a certain configuration of thicknesses.

Newest Standard PCB Thickness

Rush PCB UK makes printed circuit boards conforming to JIS, IPC/JPCA, UL, and other standards. The materials and the thickness of the PCB, therefore, vary depending on the standard the PCB must follow.

In actual practice, the PCB thickness, apart from the thickness of the board, also includes the thickness of the copper foils, both in the external and internal layers, the thickness of the plating, the thickness of the solder mask, etc. The overall thickness, therefore, depends on the materials the manufacturer is using for fabricating the printed circuit board.

The newest standard for PCB thickness is: 0.70 mm, 0.80 mm, 0.95 mm, 1.00 mm, 1.27 mm, 1.50 mm, 1.60 mm, 2.00 mm, 2.40 mm, 3.00 mm, 3.20 mm, 3.50 mm, 4.00 mm, 6.40 mm, etc.

Conclusion

Where earlier, the standard PCB thickness was 1.57 mm or 0.062 inches, with modern-day PCBs it has changed to 1.6 mm or 0.0629 inches. However, Rush PCB UK makes PCBs thinner than or thicker than the standard thickness also, depending on the requirement based on the PCB’s application.