Small-Scale PCB Manufacturing

How To Get Small-Scale PCB Manufacturing in UK

Rush PCB UK is a one-stop manufacturer of PCBs catering to the requirements of small-scale users like electronic enthusiasts, developers, and makers. Small-scale users typically take the next step of creating a professional custom PCB board. For these users, we, at Rush PCB UK offer a unique service of full manufacturing and assembly of PCBs. So far, our services have helped more than 300,000 electronic enthusiasts in completing their projects in time.

As an enthusiast, you may have tested your circuit on a breadboard and would now like to create a small prototype run of PCB boards. You can start with one of the many circuit design and PCB design applications freely available on the web. You can choose from DesignSpark PCB, Fritzing, gEDA, ExpressPCB, BSch3V, Osmond PCB, TinyCAD, ZenitPCB, PCBWeb Designer, or KiCAD, to name just a few.

Small-Scale PCB Manufacturing

Benefits of Using Rush PCB UK

We offer a one-stop small-scale PCB manufacturing and assembly service, with stringent quality control—the major benefit of using Rush PCB UK. We also offer additional services like prototyping your first boards and low-volume production. We can easily scale up the volumes when your design reaches the market. We market ourselves as one of the most experienced PCB manufacturers and SMT assemblers in the UK. We take pride in our customer services and cover all areas of manufacturing and assembling PCBs, including making prototypes. We strive to build the best possible product for our customers.

Manufacturing PCBs involves complex processes with a wide variety of different activities. However, Rush PCB UK strives to remove all complexities of PCB manufacturing and assembly for both newcomers as well as experienced customers.

Please visit our website to understand how we automate this process and to learn from our online videos about our production methods and techniques.

Using our online services, customers can easily and quickly place orders for PCB boards and assemblies. They can receive immediate updates on the production status once they have placed their order. After fabricating the boards and assembling them, we send them directly to the preferred delivery address of the customer. We also offer total tracking through the customer’s online account.

Free File-Review Service

On our website, you can order a minimum of five PCBs along with a free file review service. Our trained and professional technicians review your files to make sure the design files are ready for manufacturing before you part with your hard-earned money.

24 Hour Customer Support

We provide our customers full assistance at all times through our 24-hour customer support. Our customer support service personnel are available to respond to your telephone calls or emails promptly. Therefore, you can upload your designs from anywhere and at any time convenient to you. Our service staff will follow your order as soon as you have submitted your Gerber files, right up to the time when you satisfactorily receive your PCB boards or assembled boards.

Contact Us today to place your order for PCBs/PCBA. At Rush PCB UK, we are continually improving our service portal and our manufacturing processes.

PCB Trace Width and Spacing 

What Decides PCB Trace Width and Spacing 

Rush PCB UK fabricates all types of PCBs. We also design some boards, where it is necessary to route the traces. However, as designs grow in complexity and size, routing traces can be highly challenging. It requires judicious decisions on the part of the designer to optimize the trace width and spacing.

This is because the designer may have to address each net with its unique routing characteristics for it to function as intended. Additionally, nets may require routing in different layers apart from the specific areas that the designer can use. This calls for different PCB trace widths and spacing that the designer must manage.

PCB Trace Width and Spacing 

Challenges in Routing

For simple circuit boards, routing traces is typically a straightforward procedure, with the designer assigning all traces with a default width and spacing. This works fine, except for power and ground connections that may require wider tracks or a copper area. However, with growing complexity of circuit boards, the requirements for trace width and spacing become more complicated. For instance, a circuit board may have some or all of the following:

  • Specified widths and spacing for controlled impedance routing.
  • Wider spacing of sensitive high-speed traces to prevent cross-talk.
  • Wider traces but close spacing for power and ground connections.
  • Multiple trace widths to handle different currents in power supplies.
  • Wider spacing between analog and digital traces to isolate them from each other.

In addition, the functionality of a circuit may dictate the various widths and spacing requirements. This requirement may also come from the location of the traces. For instance:

  • Traces passing in between closely spaced pins of a connector may require using a smaller width.
  • Escape routing from fine-pitch components like small outline packages or quad flat packages may need trace width reduction.
  • Traces routing in and around pins and vias of ball grid arrays may require shrinking widths.
  • Vias may also dictate the width and spacing of traces. Apart from regular vias, a designer may also use microvias for high density interconnect designs that require thinner traces and spacing.

Signal Integrity in Digital Circuits

Although most trace routing for digital circuits is adequate with default trace widths and spacing, some high-speed signals may require specific trace width and spacing to meet controlled impedance. Usually, the board layer stackup design factors in the calculations for specific trace widths. To avoid cross-talk in high-speed but sensitive traces, designers may have to increase the spacing.

Analog Circuits

Analog circuits also require varying trace width and spacing depending on the purpose of the circuitry. Some constricted areas may require thin traces closely spaced, but the designer must also take care that PCB fabrication will not compromise the connections.

Ground and Power Routing

Depending on the current flow in the track, traces for routing ground and power may need to be wider. Wider tracks have lower resistance that allows them to remain cool while passing high currents. Tracks handing ground and power in the inner layers may need to be wider to enable them to disperse heat more effectively, as compared to traces on the top and bottom surfaces of the board, where they are exposed to air.

Wider traces also help to reduce inductance, thereby improving noise sensitivity of the board. High voltage operation may require more spacing between traces to prevent arcing between them.

Ease of Fabrication

It is easier to fabricate wider traces. As making the traces requires chemical etching, it is more effective for wider traces and larger separation. Making the trace as wide as possible and keeping them far apart is advantageous for PCB fabrication. However, this may not always be possible, considering the circuit functionality requirements.

Circuit Board Assembly

Assembling components on very wide traces may be troublesome, as the extra width may conduct heat away from the joint very quickly, resulting in a dry solder joint. During reflow, the presence of a large ground or power track may result in uneven heating, leading to several poor solder joints, tombstoning, and other effects that call for manual touch up activities.

Conclusion

Designers need complete control over rules defining trace routing, their widths, and spacing. Most PCB CAD Design software packages allow defining multiple width and spacing for traces, along with the necessary simulation for inductance and signal integrity verifications.

Remove Flux Residue From PCBs

How to Remove Flux Residue From PCBs

Rush PCB UK recommends the use of flux when soldering components on printed circuit boards. Flux is a synthetic agent capable of removing adulterants from metal surfaces, making them ready for proper wetting by molten solder. The electronic industry commonly uses solder flux for PCB assembly.

Flux has additional functions as well. It melts and covers the metal surfaces during the soldering process, thereby preventing them from being oxidized by air coming into contact with them. Flux also removes adulterants that may be present on the metal surfaces, enhancing their wetting capabilities. However, although flux has several good attributes, the residue it leaves on the PCB surface is a matter of concern.

Remove Flux Residue From PCBs

The residue that flux leaves on the board after completion of soldering looks like white or yellowish powder sticking on the PCB. Unless the assembler cleans the residue properly, it can cause long-term damage to the assembly such as reducing the surface resistivity, leading to current leakage and unpleasant results. Ignoring the flux residue can result in unexpected results:

  • A weak ion flow path between copper traces and pads under different conditions.
  • The presence of a trace amount of flux is good enough for creating the leakage paths.

The above issues has resulted in solder manufacturers offering no-clean solder that leaves little or no residue.

Why is Flux Necessary?

Solder is the process of anchoring metallic components on a printed circuit board. Molten solder wets the copper pad and the metal lead of the component to form a metallurgical connection. As the solder cools, it solidifies and also anchors the component to its pads. This process requires the metal surface of the board to be as clean as possible. Cleaning the surfaces prior to soldering prepares them for a perfect bonding with solder.

Solder manufacturers offer flux as a synthetic cleaning agent useful during and after the soldering process. Flux ensures the surfaces are ready for soldering by cleaning and removing any pollutant like oil and grease from them. It also establishes a film over the metal surfaces, preventing them from coming into contact with air, as pollutants present in air can lead to oxide formation on the metal surfaces. It is difficult to solder metallic surfaces when there is oxide on them.

Flux also serves as a protection against deoxidizing the metal surfaces undergoing soldering. It contains chemicals and additives that not only hamper oxidization, but also aids the soldering process. Flux is available in various forms like paste, liquid, or solid form depending on its usage.

Types of Flux

The electronic industry uses three types of flux, depending on the application:

Selective Soldering — This is liquid flux. The operator must spritz it on a select portion of the PCB. They do this by a specific process of jet drizzle.

Wave Soldering — This is also liquid flux. The operator must spritz it on the entire board during the preheating stage before the PCB assembly goes for the final soldering. The hot flux removes pollutants and oxidized layers that could hinder the soldering process.

Reflow Soldering — This is a paste type of flux mixed with solder paste. The operator applies the paste through a stencil. The process controls the amount of solder paste deposit. It deposits a small amount of paste on the solder pad of the board. This paste holds the component in place until the heat of the oven melts the solder paste and anchors the component to the board. Prior to the solder melting, the flux cleans the surfaces while also covering the metal surfaces, preventing them from oxidization.

Why is it Necessary to Clean Flux

Flux residue is often present on the soldered elements, especially on the PCB surface. This could cause issues in the long run. Therefore, cleaning the flux residue is an important part of the PCB assembly process. Major benefits of cleaning the flux residue are:

Preventing Corrosion of PCB and Components

The flux residue after soldering is acidic and, therefore, hygroscopic. Allowing it to remain on the PCB surface for a long duration may attract water from the surrounding air, leading to corrosion of the metal surfaces. Cleaning the flux residue prevents this corrosion.

Enhancing the Appearance of the PCB

Presence of flux residue on the PCB not only makes it look unattractive, it can also lead to the misconception of an ineffective quality control procedure. Customers might find the PCB assembly repulsive, and this can also lead to a reduction in business volumes.

Improving the Integrity of the Manufacturer

As a vital aspect of business, integrity helps sustain competitiveness. PCB manufacturers sustain their competitiveness by systematically providing good values and earning customer satisfaction in return. By presenting a clean PCB bereft of flux residue, PCB manufacturers make their products more dependable and durable. This maintains relevance, while upholding the manufacturer’s integrity.

How to Clean Flux Residue From PCBs

Using Acetone or Isopropyl Alcohol — Acetone or Isopropyl Alcohol dissolves flux residue readily. The technique is to use a brush dipped in the liquid and gently remove the flux residue from the board. The operator must be careful and apply gentle strokes with the brush to avoid damaging soldered joints. After removing the flux residue, the operator must wipe the excess liquid using a parched cloth, and allow the board to dry up.

Using Industrial Cleaning Agents — Solder manufacturers offer various types of cleaning agents, especially suited to remove flux residue left by the solder paste they make.

Application of these chemical agents may require spraying or brushing it on the board. In some cases, it may also require immersing the PCB assembly in the cleaning solution.

As the cleaning liquid dissolves the flux residue, the operator can wipe the excess with a soft cloth, and allow the board to dry.

Using No-Clean Flux

Manufacturers also offer no-clean flux that produces very low amounts of flux residue deposits on the PCB surface. It is a combination of some inorganic agents blended with organic resins. The operator must use it with the solvent compositions that the manufacturer specifies, to achieve the best results. With proper use, it is not necessary to clean the quantity of flux residue that remains on the board, and the operator may safely ignore it.

Conclusion

Cleaning the flux residue is a tactical approach that PCB manufacturers use to maintain their competitiveness in the industry. Rush PCB UK recommends cleaning flux residue for sustaining the competitive advantage, as it improves the reliability and aesthetics of the PCB

Calculate PCB Trace Width

How to Calculate PCB Trace Width

There are two PCB trace width calculators available in the market — one based on graphs published by IPC 2221, and the other based on graphs published by the latest IPC 2152 standards.

The calculator (https://ninja-calc.mbedded.ninja/calculators/electronics/pcb-design/track-current-ipc2152) or (https://twcalculator.app.protoexpress.com/) based on the latest IPC 2152 standards is more accurate and requires more data input. However, for general purpose use, the calculator based on IPC 2221 is also helpful.

Both calculators find the minimum PCB track width for a specified continuous current and temperature rise. The calculations take into consideration the thickness of the copper track, its distance from planes, the entire thickness of the board, and the material the PCB uses.

IPC 2152 provides graphs, and the trace width calculator uses equations from the data extracted from these graphs. For this, the designers used the tool WebPlotDigitizer, with which they fitted suitable trend lines to the graphs.

The accuracy of the calculator based on the graphs provided by IPC 2152 is quite high, as long as the range of data lies within that provided by these graphs. Beyond this range, the equations tend to extrapolate, but the results can be inaccurate.

The calculator assumes the current to be DC and, hence, constant. However, it is also possible to use the RMS value for a pulsed current, provided the pulses are fast enough.

All PCB materials have a relative thermal index or RTI, and the designer must take care to never exceed the temperature of the PCB material beyond this RTI. The Underwriter Laboratories define this RTI as the temperature at which it is possible to retain at least 50% of the material properties of the material after 100,000 hours. However, this calculator will not take into account heat sources that are active nearby.

Details of Trace Width Calculator Based on IPC 2152

The calculator is basically a three-in-one calculator. The three parameters involved in the calculation are — trace width, maximum allowed temperature rise above the ambient, and maximum current capacity of the trace. Out the three, if the designer knows any two, the trace width calculator can calculate the third.

Additionally, the calculator also provides the DC resistance and the voltage drop across the trace for a given length. 

Expectations from the Trace Width Calculator

Trace width calculations are always critical for PCBs carrying high currents. Therefore, the designer must know the trace width that is just enough for carrying that high current. For instance, if the trace width is not adequate, the current flow may burn out the trace, and impact the functionality of the PCB.

With the trace width calculator, the designer can calculate only the trace width, but also the temperature rise and the amount of current the trace can handle. By altering any two of these parameters, the designer can find out the effect they have on the third parameter. 

As the calculator is based on the IPC 2152 graphs, the calculator provides the temperature rise in not only external traces (on the external surfaces of PCBs), but also in internal traces (buried in the internal layers of multi-layer PCBs).

For instance, the calculator shows that internal traces can also carry quite high currents similar to those external traces can carry. Convection air flow on external traces keep them cooler, and hence, they can carry higher currents. The trace width calculator allows change of units as necessary by the designer.

Using the Trace Width Calculator

While designing traces on a PCB, designers essentially consider four main parameters:

  • Trace Width (W)
  • Rise in temperature (ΔT)
  • Maximum Trace Current (Imax)
  • Trace Thickness (Th)

If the designer knows the Imax and ΔT, then the trace width calculator can provide the trace width for both internal and external traces.

The tool requires ambient temperature input and the trace length also. With these extra inputs, the tool can calculate additional parameters such as trace resistance at ambient and at elevated temperature, maximum voltage drop, and maximum power loss.

Conclusion

The trace width calculator based on IPC 2152 is a versatile tool for PCB designers. They can use it in multiple ways to calculate various parameters of a PCB trace under different operating conditions.

Shorts on Printed Circuit Boards

Detecting Shorts on Printed Circuit Boards

It is not an uncommon experience for engineers to find that their newly assembled printed circuit board has a short. Not only does a short prevent the board from functioning as intended, but it may also lead to an uncontrolled current consumption, leading to damage to a few components or to the tracks on the board. According to Rush PCB Ltd, it is necessary to have an understanding of the cause of shorts in PCBs to know how to detect them. Shorts may appear in bare boards and in assembled boards.

Cause of Shorts in Bare Printed Circuit Boards

Lack of proper reviews and inspection methods is the major cause of shorts in bare printed circuit boards. This usually happens due to:

Design issues

While laying out the traces during the design phase, a designer may overlook maintaining the minimum distance between two traces, a trace and a pad, and between two pads. This may be due to inadequate applications of Design Rules and subsequent slip-ups in DFM reviews.

Inadequate etching controls

Inadequate etching may result in copper slivers remaining between adjacent copper instances on the PCB. A proper inspection regime should be enough to detect such deficiencies and adjust the process controls to overcome them.

Cause of Shorts in Printed Circuit Board Assemblies

Shorts may appear in a PCB assembly, even when the bare board did not have any. There may be several reasons for such shorts to occur:

Solder Shorts

Presence of excess solder is the most common reason for shorts. Extra solder bridging two neighboring pads can cause a short. Manual soldering is one of the major reasons for deposition of excess solder leading to shorting between adjacent pins. Another reason is excess solder paste deposition through a thick stencil.

Component Shorts

Neighboring components with metallic bodies may touch each other to cause a short. This is common in boards with through hole components, where components standing out on board is a regular affair, but it is rare with surface mount components.

A damaged component may also be the source of a short. If the component has developed an internal short, it may not be visible externally. However, once the board assembly is powered up, the components acts like a short.

Detecting Shorts in Bare Printed Circuit Boards

Manual Methods

Using a multimeter is an adequate arrangement for detecting shorts in bare PCBs manually. The inspector requires a knowledge of the various individual nets on the board. Test pads provided by the designer makes the testing easier.

The multimeter must show high resistance between any two nets. Any indication of low resistance is due to an unwanted short.

Automated Methods

For quick detection during high volumes of production, automated methods are preferable. Test pins or flying leads touch test pads and assess the resistance between them. A computer compares the readings collected with reference readings from a known good board, highlighting the differences.

Detecting Shorts in Printed Circuit Board Assemblies

Detecting shorts in assembled PCBs is more complicated, and requires the inspector to have experience and ingenuity. Testing for shorts in assembled circuits requires powering the assembly, typically through a current limited power supply, to avoid damaging components.

Depending on the nature of the short, it may be possible to detect it using visual methods or through instruments.

Visual Inspection

If a short circuit is causing a rise in temperature somewhere, it may be easy to spot visually or by touch. The temperature of a trace going up due to a short may discolor the trace, making it easy to locate. A solder short on two adjacent pins of a component may cause a rise in the temperature of the component. Touching components with a finger may help in detecting the hot component.

Thermal Imaging

A thermal image of an assembled board after power-up can give a clue to the presence of a short. Automated devices can compare the thermal image of the test board to that of a reference board, thereby flagging any discrepancies.

Damaged Component

A component with an internal damage may deteriorate when the board is powered up. This may result in visible signs like a bulging capacitor can, a discolored resistor, or flaking colors giving an indication of the fault.

Conclusion

There are various ways a short may manifest itself in a printed circuit board, depending on whether the board is bare or assembled. Detecting the short or shorts quickly depends on the nature of the short and the methods used by the inspector. Rush PCB Ltd recommends understanding the effects of the short to lead to a quick detection.

Standard PCB Board Panel Sizes

Standard PCB Board Panel Sizes

Rush PCB UK uses the latest technologies for making PCBs. Although the production processes for making PCBs are not always easy, we automate most of them. For this, we use special software for parts of the work, especially when we produce PCBs in large quantities. For those new to the world of printed circuit boards, we would like to explain things crucial about PCB manufacturing like standard PCB panel sizes, and why Rush PCB UK is one of the best companies from where to get your printed circuit boards.

 

Why PCB Panels?

Our customers have their own reasons of getting their PCB made. These reasons are extremely diverse, and the same is true for the myriad sizes of PCBs in the market. Rather than fabricate boards of various sizes, manufacturers prefer to standardize them by designing them in panels.

Once the designer has made a custom printed circuit board, they put them in standard panels. This depends on the manufacturer, as they decide the panel size most suitable to them for optimizing the output, reducing the cost, and improving the quality of the board.

Manufacturers use different methods for depaneling or removing individual boards from the panel. Some use the V-groove method, while others use the tab routing method. The method of depaneling depends on the design of the PCB, and the manufacturer chooses the method that causes the least damage to the boards when removing them from the panel.

Standard PCB Board Panel Sizes

Deciding the PCB Board Panel Size

Another factor that plays a major role in deciding the panel size is the thickness of the PCB. The thickness of a board depends on its application—thicker boards are necessary when it is known that they will be subject to high amounts of vibration, while thin and flexible boards are useful where they will be subject to flexing and bending.

Typically, an average circuit board is 0.063 inches (63 Mils, 1.6 mm) thick. For achieving the highest quality, manufacturers take into consideration the board thickness while deciding the processes for fabrication. They calculate the panel size accordingly so that the area utilization is maximum.

Apart from the size and thickness of individual boards, the panel size also depends on the method of depanelng or separating the individual boards from the panel. This is because the method the manufacturer will use for depaneling decides the separation and clearance between adjacent boards.

When constructing a printed circuit board, manufacturers choose a standard PCB panel size to make their work faster and more efficient. For a standard panel size of 18 x 24 inches, the border clearance should be a maximum of half inch. However, for PCBs with higher number of layers, the requirement of border clearance also increases. As the number of layers increases, more marks are necessary for handling and alignment, thereby taking up more space in the border clearance.

In a board measuring 12 x 18 inches, the layout likely takes up 10 x 16 inches. However, multi-layered boards require additional assembly and marking clearance. Additionally, panels require border clearance, specific routing, and milling clearance. If all the boards in the panel are similar, the paneling is faster, and it costs less. However, if the individual boards in the panel are all different, the paneling process becomes a challenge, and requires experience and skilled professional engineers.

For identical boards, the configuration and paneling process is straight forward, as the process is geometrically identical, and it is possible to automate it by a step-and-repeat process. However, for individually different boards, this strategy fails, and positioning the boards requires an expert to do it manually.

Recommendations for Standard PCB Board Panel Sizes

Rush PCB UK recommends customers to discuss their board requirements with us before placing orders. We cooperate with our customers and try to minimize the board cost while still getting the best possible size.

Economizing the space on the standard PCB panel leads to a reduction in the cost of producing custom circuit boards. Therefore, it is necessary to discuss with us when you happen to decide on the size of your circuit board. We will guide you to resize your board such that panelization works out in the best possible manner.

Conclusion

It is very important that you select an experienced PCB manufacturing company like Rush PCB UK to get your boards fabricated. When you want a high-quality product, there will be several manufacturers who can produce PCBs for you. For us at Rush PCB UK, this is not a problem at all. We not only advise you as to the most optimum size of your PCB, but also inform you about details like dimensions of the space between individual boards and the space around the panel edges.

SMD Stencil and Laser Stencil

SMD Stencil and Laser Stencil

For assembling surface mount devices or SMDs on a PCB, assemblers require a stencil. They use the stencil as a guide to depositing the correct amount of solder paste on the footprint pads on a circuit board. Rush PCB UK recommends using laser-cut stencils to achieve high-quality soldering.

SMD Stencils

Most SMD stencils are made of thin stainless steel foils with openings for the solder paste to pass through. The operator places the stencil on the board and registers the openings to match with the component pads. They apply a small amount of solder paste on the stencil and drag it across with a metal squeegee. The solder paste passes through the openings in the stencil and deposits on the pads on the board.

Laser Stencils

To cut the openings in the stencil accurately, manufacturers use laser beams. The tiny beam of a laser is smaller than any metal tool, and therefore, can make more accurate cuts. Electro-polishing the edges of the cut make them smooth enough to release the solder paste easily.

Most laser stencils are made of stainless steel, although nickel stencils are also available. Manufacturers make the openings in the stencil using lasers. Using laser has the advantage of achieving high precision and low processing time, as there are no photo films involved. The apertures in the stencil are highly accurate when cut with lasers.

Even when cut with high-precision lasers, the walls of the apertures usually have tiny burs. These hamper the smooth transfer of solder paste from the stencil to the board. A process of electro-polishing or nickel plating removes the tiny burs, improving the transfer of solder paste.

SMD Stencil and Laser Stencil

Stencil Thickness

The amount of solder paste deposit required on the pads defines the stencil thickness. SMD stencils are typically 0.006 to 0.010 inches thick. The thickness of the stencil is important to achieve quality solder joints.

If the SMD stencil is thicker than necessary, it will deposit a high volume of solder paste. During reflow, this may cause problems for fine pitch SMDs, as the excess solder may join to create shorts. On the other hand, the high volume of solder paste may also make it stick to the edges of the opening on the stencil, affecting its transfer efficiency, and subsequent transfers. if the stencil is thin, the solder paste it deposits may not be enough to properly form a proper solder joint.

Stencil Aperture

To improve the transfer efficiency of SMD stencils, manufacturers follow stencil aperture rules. Ideally, the amount of solder paste held in the opening of a stencil should transfer totally and completely to the pad, after the operator lifts the stencil. However, this does not happen in reality. A small amount of solder paste sticks to the stencil opening walls. The ratio of the solder paste volume deposited by the stencil to the calculated volume is the transfer efficiency of the stencil, and should ideally be 1 for a specific stencil.

Stencil manufacturers follow a mathematical relationship between the stencil thickness and the stencil opening, to maximize the transfer efficiency. The aperture is usually trapezoidal, such that the bottom opening is wider than the opening at the top of the stencil. This helps to increase the transfer efficiency.

Care of Stencils

After using a stencil, the operator must thoroughly clean it to get rid of any remaining solder paste. Rush PCB UK recommends storing stencils vertically in a suitably protective environment.

Electrical Breadboard

Using the Electrical Breadboard

When working on a new project, electronic engineers prefer to test their circuits on a prototype board. This is a printed circuit board on which they mount electronic components and test the circuit functionally. If necessary, they make the necessary changes in the circuit and the layout of the board. Once the changes are satisfactory, the circuit proceeds to the final design. However, even before they go for a prototype board, the designers can do some preliminary testing with electronic components. Rush PCB UK recommends using the electrical breadboard for this purpose.

What is an Electrical Breadboard?

An electrical breadboard is a rectangular plastic board with numerous holes on its top surface. The holes allow plugging-in the leads of through-hole electronic components. This allows building prototype circuits and testing them without soldering the component leads. Unfortunately, it is not possible to use surface mount components with electrical breadboards. Therefore, designers test their circuits using through hole components and move over to using surface mount components when going for prototype PCBs.

The name breadboard is a leftover from early days of electronics, when people would use nails and screws driven into wooden boards to connect components. As the boards were initially meant for cutting bread, the name stuck.

Structure of Breadboards

The modern breadboard is made of plastic, and is available in various shapes, sizes, and colors. Most common are the full size, half size, and mini size of breadboards. Most breadboards come with notches and tabs on their sides. This allows snapping more boards together to build one large breadboard.

Electrical Breadboard

Figure 1: Electrical Breadboard

A full size breadboard has its holes arranged in rows and columns. The longer sides have two rows of holes each, and the arrangement of 30 columns are in two groups, A to E and F to J.

The breadboard does not require soldering components to connect them. Under the board, each hole has a brass connector with spring leaves. When the designer pushes the lead of a component through a hole, the spring leaves of the connector anchor it securely. The design of the spring leaves is such that it is easy to pull out the lead and plug it into another hole.

The interconnection between the brass connectors makes the breadboard so convenient for building circuits. The two rows along the longer side of the board have the connectors joined individually. Therefore, the designer can use them as power buses. They can designate the outermost rows on the two longer sides as the ground or the negative bus and the rows immediately on the inner side as the positive bus of a DC power supply.

Likewise, the two groups of 30 columns also have their connectors interconnected individually. However, there is no interconnection between the two groups. They are also isolated from the power buses.

Using the Breadboard

The design of the breadboard is such that the rows E and F have a separation of 0.25 inches between them. This allows placing an IC such that it straddles the rows E and F. Each pin of the IC is then extended by four connections. The designer can plug in resistors, capacitors, and other components between the pins of the IC. They can make other electrical connections with the help of wire jumpers.

Using the Breadboard

Img Source: https://cdn.sparkfun.com/assets/0/3/f/f/1/51758c9ece395fd266000000.jpg

Conclusion

With no special tools necessary to use them, breadboards are a great way to build electronic circuits. As there is no soldering necessary to interconnect components, even newcomers to electronics can experiment with components to build and test circuits. Once they have finalized the circuit and tested it on a breadboard, they can develop a prototype board that Rush PCB UK will gladly fabricate for them.

Read More about: How do Circuit Boards Work?

FR4 Printed Circuit Board

All About FR4 Printed Circuit Board Material

According to Rush PCB UK, FR4 is the most common material that PCB manufacturers use to make printed circuit boards. Most individuals and engineers in the electronic industry are familiar with FR4 as the base material for building rigid circuit boards.

What is FR4?

The name FR4 or FR-4 is a combination of an acronym and a grade. The FR stands for Flame Retardant and the 4 is the mark of a grade of the material. FR4 is an epoxy laminated fiberglass reinforced sheet that printed circuit board manufacturers use. The grade 4 indicates the base quality of the laminate sheet.

Under the FR4 name, there exist a variety of sheet materials and designs, with the number differentiating them from others in the same class.

FR4 has a composite structure. Fiberglass, woven into thin cloth-like sheets, is bound with a flame-resistant epoxy resin, to form a base layer for a printed circuit board. While the fiberglass gives the material its structural stability, the epoxy gives FR4 its material rigidity. FR4 also has several other physical properties that make it so popular among engineers and designers as a base PCB material.

How PCBs Use FR4

The FR4 in a PCB forms its primary insulating backbone. Board manufacturers laminate the FR4 sheet with copper foil on both sides using adhesive and bond them with heat and pressure to form a copper clad. PCB manufacturers use the copper clad to build printed circuit boards. Depending on the design, they etch the copper foils to form circuits on which they solder electronic components.

Complex PCBs can have more than just two layers. Manufacturers etch Inner layers of copper foils to form specific circuits and bond all the layers to form a single multilayered PCB. Vias form the interconnections among the inner and outer copper layers. The outermost copper layers need a covering of solder mask to keep them from being tarnished and oxidized from chemicals in the atmosphere. A silkscreen layer helps in the assembly process.

Depending on the application, designers choose the FR4 and copper foil thicknesses. Unless the board has to withstand severe vibrations, designers use standard thickness FR4 material. The copper foil thickness depends on the current the board must handle.

When to Use FR4

Designers prefer to use FR4 based printed circuit boards for its mechanical strength, reliability, good electrical insulation, and relatively low cost. However, FR4 material is not suitable for boards handling high-frequency signals, which require special laminates for better signal integrity.

PCB Thickness

When ordering a printed circuit board for a project, the designer must specify the number of layers and its thickness. Depending on the needs of the project, the thickness of the FR4 board may vary significantly. This is an essential feature and affects many aspects of the functionality of the board.

Advantages of Using FR4

FR4 materials are popular among electronic engineers in the industry as FR4 offers several advantages:

  • Easy to design and fabricate
  • Low-cost materials
  • Makes compact boards
  • Provides good bonding with copper foils—high peel-off strength
  • High mechanical strength
  • Highly resistant to moisture
  • Good electrical insulating properties in humid environments
  • Can withstand high temperatures
  • Can be fabricated into multiple layers
Properties of PCB Materials

Properties of PCB Materials Ref: https://www.semitracks.com/newsletters/images/august/2015-august-newsletter-image-1.png

Types of FR4 PCBs

Depending on the filler material, it is possible to make various types of FR4 boards such as:

  • Halogen-Free PCBs
  • Single-Layer PCBs
  • Double-Layer PCBs
  • Multi-Layered PCBs
  • Rigid-Flex PCBs

Conclusion

Being a widely relevant material, FR4 is popular mostly for its low cost and relative electrical and mechanical stability. Although FR4 material is popular for its extensive benefits, it is not the best material for high-frequency applications. For any requirements of PCBs made from high-quality FR4 material, please contact Rush PCB UK.

Types of Prototype PCBs

All About Double-Sided Prototype PCBs

Electrical and electronic industries use printed circuit boards or PCBs for various activities and equipment. These boards may be single-, double-, or multi-layered, with copper traces on each layer confirming to certain schematics. PCBs hold the necessary electrical and electronic components in place with solder, allowing easy wiring and assembly. However, before committing to manufacturing PCBs in large numbers, Rush PCB UK recommends designers test their circuits using prototype PCBs.

What are Prototype PCBs

Prototype PCBs are general purpose boards available off the shelf. Designers typically use these boards to assemble their circuits and test them for their functioning. Once the designer is satisfied the assembly is functioning according to their requirements, they can proceed to the next step towards designing and layout of the actual board.

The structure of the prototype PCBs is such that it is easy to desolder any component and replace it with another. This feature is helpful to designers, since it allows them to change components if the circuit does not function as desired.

Types of Prototype PCBs

The structure of prototype PCBs varies depending on the type of components the designer is planning to use in their application. In general, there are two major types, depending on whether the designer is using Through-Hole Components (THCs) or Surface Mount Components (SMCs).

THCs have long leads protruding from the body of the component. The PCB requires holes to allow the component leads to pass through for anchoring and soldering. It is possible to solder the components manually using a soldering iron, or using a wave soldering machine.

SMCs have very short leads that do not require holes for mounting. It is possible to place the SMC on the board and solder the leads directly to the pads on the board. For medium size SMCs, it is possible to manually solder them using a fine-tip soldering iron. However, it is possible to use a table-top reflow machine to solder SMCs on prototype boards.

Double-Sided Prototype PCBs for THCs

Two popular types of double-sided prototype PCBs are available for use with THCs:

Perf Boards: These are double-sided FR-4 boards with identical patterns on both sides. Each perf, or perforated board, has 1 mm holes drilled at 0.1 inch pitch all over it. Each hole has an unconnected square or round copper pad surrounding it. The holes are not plated through. In general, the boards are available in various sizes such as 4 in x 3 in, 6 in x 6 in, 4 in x 8 in, 6 in x 8 in, and so on.

Strip Boards: Similar to perf boards, strip boards are also double-sided FR-4, with 1 mm holes drilled at 0.1 inch pitch all over. While all the holes have square or round copper pads surrounding them, each pad connects to its horizontally adjacent neighboring pad with a copper trace, with the trace running from the left edge of the board to the right edge. The reverse side has a similar circuit, only the trace connections are vertical rather than horizontal, with each trace starting from the top of the board and running to its bottom. Therefore, the board has many parallel strips of copper trace on each side, with the strips running at right angles on the two sides.

Types of Prototype PCBs

 

Double-Sided Prototype PCBs for SMCs

Two types of double-sided prototype PCBs are available for SMCs:

General Purpose Customizable Boards: These are double-sided FR-4 boards with patterns on both sides. The patterns have pads capable of accepting various SMCs sizes for resistors, capacitors, inductors, edge mount connectors, and SMA connectors. These boards generally available for medium-sized SMCs like 1210, 1206, and 0805.

Several plated through holes (PTH) are available very close to the component pads but not connected to them. These PTHs help the designer to easily connect to the circuit on the other side.

Specific Purpose Boards: These are double-sided FR-4 boards with specific patterns on both sides. The circuit on each side has pads for SMCs arranged in clusters of 4, 5, or 6 components. Designers can use SMCs of 1210, 1206, and 0805 sizes on these boards.

The boards have numerous PTHs placed close to the clusters of SMC pads. These help the designer to allow connection to the circuit on the other side of the board.

Specific Boards for SMC ICs: These are double-sided FR-4 boards with a specific SMC IC pattern on one side of the board, along with pads for discrete SMCs. The IC pattern has only pads for a quad package or dual-in line package IC. The pads are usually long to allow mounting different sized packages. All the pads have a neighboring unconnected PTH to allow connection to the reverse side.

How to Use Prototype PCBs

The basic idea of using prototype PCBs is to build a circuit using electronic components and test its functionality. The designer selects the type of prototype board depending on whether the circuit uses THCs or SMCs.

Using Prototype PCBs for THCs

For THCs, designers can use either perf, or strip boards. In general, beginners find perf boards or perforated boards easier to use because they can interconnect components using short pieces of wire or even with solder bridges. The leads passing through the holes also double as connections to the other side of the board.

Experienced designers find the strip board more useful, as they can use the strips as interconnections between components. For a short interconnection, they can interrupt the excess strip on either side with a sharp cut.

As most through hole ICs have a pin pitch of 0.1 inches, placing ICs on the perf, or strip board is easy. However, the designer must ensure the strips do not short the pins of the IC.

Using Prototype PCBs for SMCs

Using prototype PCBs for SMCs is somewhat different from those for THCs. The complexity arises because of various factors. SMCs are available in various package sizes. SMC ICs can have quad packages or dual-in-line packages and their pins can be in gull-wing, J-wing, or flat shape. Fortunately, most manufacturers offer the same IC in different packages, so the designers can choose accordingly.

Conclusion

Rush PCB UK recommends designers use prototype boards for testing the functionality of their circuits before finalizing their designs. Having to redesign a board results in unnecessary delays and cost overruns, making the design late to the market. Using prototype boards is an easy way for the designer to maintain the schedule according to the plan.