Tag Archives: SMT assembly

Design Elements Influencing SMT Assembly

Design Elements Influencing SMT Assembly

Smart devices should perform well to satisfy consumers who want high-density devices. The Surface mount technology or SMT helps develop high-end electronics. The process of SMT involves soldering which goes through different problems due to PCB pads, reflow technology, stencil design, quality of the soldering paste, and different technical parameters.
SMT manufacturing involves many challenges and different design elements influence it. The supplier needs Gerber files and design data for the placement of components. Gerber files help configure different SMT manufacturing machines and develop stencils for placing the solder paste on the circuit board. The manufacturer and designer should discuss the design parameters and elements for precise SMT manufacturing.
So, different elements affect the quality of SMT that we will discuss below.

Making Bill of Materials (BOM)

SMT has various features and BOM is one of them. The flow of soldering has close contact with the bill of materials. You have to consider the below factors to create a high-quality SMT.
• Components packaging should be compatible with mounting requirements.
• The component figure should be according to the SMT requirements to get the desired shape with precise dimensions.
• The PC BOARD pad soldering should be compatible with the reflow technology to prevent its oxidation and the same applies to the solderable ends of the elements. If these two factors get polluted, it would result in defective solderings, such as solder beads or pseudo soldering. The same is true regarding the humidity sensor and PCB administration.

Design Elements Influencing SMT Assembly
Design Elements Influencing SMT Assembly

PCB Pad Design

PCB design highly influences the manufacturing of SMT in terms of quality. According to HP research, 80% of SMT manufacturing defects occur due to the poor design of a PCB. So, the designer should focus on essential factors, including the folder mask, layout of components, type of the substrate substance, thermal pad design, assembly techniques, component packages, the position of vias, optical positioning, and the transmission boundary.
If the PCB pad design is poor, it would result in deflected soldering even if the mounting position is fine. Like, tombstoning or disposition of components can happen. You can avoid these issues by considering the key aspects while designing the SMT pad, such as the distance between the pads, residual size of the pads, width and symmetry regarding pads, and avoiding through-hole vias.

Printing of Solder Paste

The paste of solder should have a compatible printing technology, or it will affect soldering. A poor printing of solder paste results in a deflected PCB that you have to revise. During the printing of solder paste, you should consider three essential elements, such as solder paste, scraper, and stencil

Quality of The Solder Paste

Solder paste is an integral part of reflow soldering, and it’s a combination of alloy and flux. Precise soldering joints depend on the powder of alloy, whereas the flux removes oxidation from the surface to ensure high-end soldering. Even, the paste of solder having 50 percent of solder of alloy can be enough if it has high quality. Two key factors of soldering paste, including storage and application, determine its quality. Make sure to store the solder paste at appropriate temperatures ranging from 0 to 10 degrees.

PCB Stencil

The pad of the PCB should have evenly applied solder paste through a stencil, which is a major factor in Printed Circuit Board printing. Moreover, the eminence of the stencil affects the printing eminence. The stencil is designed through different techniques, including laser cutting, and chemical corrosion. You can design stencils by considering certain characteristics, such as:
• The thickness of the steel sheet
• Aperture design
• Mark points
• Anti-solder ball processing
• Direction of printing
• Type of scraper in terms of shape and material

Printing Parameters

You have to consider essential parameters of printing for precise results, such as frequency, scraper speed, scraper pressure, stencils down release speed, and its cleaning mode.
Both pressure and speed of scraper should be well-balanced, like not so low or so high. If these values are not balanced, it would result in defective printing, thus influencing the manufacturing.

Right Equipment

There should be accurate equipment to have high-level printing of the soldering paste. A small space and high-density PCB should follow the right printing rules for a stable process.

Understanding PCB Support

The printing of the soldering paste depends on the PCB support, as its lack can result in an uneven soldering paste. So, it is important to have uniform PCB support to keep the PCB and stencil close enough.

Components Mounting

The mounting of the PCB parts or components depends on different elements, including the right pressure for mounting, the quality of the components, and their precise location. Components should be according to the BOM, and mounted on the PCB at the right place, following the right dimensions. At the same time, the mounter should be precise in this case to ensure a stable mounting of the components onto the PCB pads.
The mounting angle should be correct, besides, the mounting pressure should be suitable, like not too high or low. You can evaluate mounting through different elements, such as the thickness of the board, components’ package, mounted z-axis, and nozzle’s pressure.

Quality of Reflow Soldering

The temperature curves of the reflow soldering should be well-set to have high-quality soldering of areas to be welded. An increased temperature can affect the PCBA due to heat occurring at a fast rate. It would cause PCB deformation, damaging the components. Besides, the soldering paste has a solvent that gets volatile, splashing out the metal composites as tin’s plating balls. Engineers apply nitrogen reflow soldering to get rid of oxidation, enhancing the quality of soldering.
Moreover, make sure that the reflow soldering is compatible with the PCB substrate, size, material, weight, and thickness. Besides, it should be according to the reflow oven’s structure, and the temperature zone’s length should also be considered.
SMT assembly is easy to optimize by having the best PCB design and software to analyze it. The right design software helps you to set assembly standards without missing any factor.

Additional Information

The solder paste is applied to the pads through a machine by holding the stencil tightly on the PCB. Then components are placed according to the footprints with the help of optic technology. The engineers inspect the placement of the components through an optic machine to make sure it’s free from flaws, and this should be done before reflow soldering. Sometimes the x-ray technology is used for inspection which is essential before PCB testing. Such inspection helps detect poor solder joints, as well as short circuits that happen during the reflow soldering.
The placement machines are unable to hold a PCB if the PCB edge is crowded with components, and this can influence SMT manufacturing. You also have to consider the tooling strips for miniature PCBs. The tooling strips should be at least 6 mm to help a machine have a proper grip during the PCB assembly. You can also give the V-score on the tooling strips to separate the parts easily in the later stage.
Keeping the SMT components in one direction can also reduce the flaws and helps have placement the components in one go. So, the selection of the components and their placement affects the SMT assembly, making it smooth or horrible.

Frequently Asked Questions

What is PCB?
PCB is an abbreviation of Printed Circuit Board. It is used in electrical devices to provide them with signals or currents to operate. Printed circuit boards are used in different industries, including networking, electronics industry, gadgets, aerospace, and much more.

What is SMT in PCB?

SMT stands for Surface mount technology, and it helps develop high-end electrical devices.

What is Soldering in PCB?
Soldering is a manufacturing technique in PCB where two metals are connected through another material’s fusion. It should be precise because poor soldering results in a device malfunction.

What Are Important Characteristics Of A Stencil Design In PCB?
Stencil design depends on certain characteristics, such as the thickness of the steel sheet, aperture design, mark points, anti-solder ball processing, the direction of printing, and the type of the scraper in terms of shape and material.

Final Thoughts

Smart devices should perform well to satisfy consumers who want high-density devices. The Surface mount technology or SMT helps develop high-end electronics. The process of SMT involves soldering which goes through different problems due to PCB pads, reflow technology, stencil design, quality of the soldering paste, and different technical parameters.
SMT manufacturing involves many challenges and different design elements influence it. PCB design highly influences the manufacturing of SMT in terms of quality. According to HP research, 80% of SMT manufacturing defects occur due to the poor design of a PCB.
The PCB designer should focus on essential factors, including the folder mask, layout of components, type of the substrate substance, thermal pad design, assembly techniques, component packages, and the position of vias, optical positioning, and the transmission boundary.
Like to know more about the Design Elements or PC Board Fabrication? Write us at sales@pnconline.com

BGA SMT assembly process

BGA is an abbreviation for Balls Grid Arrays is a greater surface mounted packaging technique. The connections at the bottom of the packaging were circular and organized in a lattice-like structure, thus the term BGA. At the moment, motherboards controller chipsets employ such manufacturing materials and technologies, primarily earthenware. BGA technology, when combined with storage packaging, allows you to produce the same size storage while increasing SMT assembly processing capability by two to three times. BGA has a smaller frame and superior thermal conductivity qualities. BGA production process has substantially enhanced every square inch of memory; employing BGA manufacturing solutions, memory devices with the same capacity require just one-third the dimensions of a standard package; when contrasted with the conventional bundle.

It is a sort of surface-mount packaging (also known as a chip carrier) for interconnected circuitry. BGA modules have been used to install components like microcomputers securely. A BGA can accommodate more connectivity pins than a double inside or flat module. Instead of simply the boundary, the entire bottom area of the gadget may be employed. The connections were also smaller on aggregate than from an outer wall kind, resulting in improved effectiveness at incredible velocities. BGA gadget welding necessitates fine management and is often performed by computerized systems. Socket installation is not possible with BGA electronics.

Connectivity

The fundamental distinction between BGA Lead frame products and traditional SMT Lead frame products is the arrays structure of soldering sectors on the packaging, which suggests different interpretations for connecting communication, voltage, and ground connections on the PCBs.
In general, overall printable circuit boards design and implementation is a critical aspect in obtaining good solder connection durability. It is not suggested, for instance, to position BGA bundles in the very same contrary places here on the Printed Circuit Board (when double-edged mounting has been used), since this results in stiffness of the arrangement and earlier solder combined fatigue, particularly in comparison to a layout in which the element places have been started shifting against one another and.

Pattern for Soldering

Mass production is used to apply solder solution to the PCB metallic pads. The stencil apertures and thicknesses influence the amount of the generated soldering solution. In most circumstances, the thicknesses of a stencil must be adjusted to meet the requirements of all devices just on PCB. This is advised to use 100 – 150 m thickness overlays for BGA modules. The stencils perforations should be circular. The opening dimension must be the same as or slightly larger than the metallic pad thickness on the PCB.
To guarantee consistent and strong soldering paste application to the PCB, laser cut (mainly corrosion-resistant) or programs/projects (Nickel) stencils should be used.

Soldering

Solder paste is made up of soldering alloy and a fluxing system. Typically, the quantity is divided into 50 percent alloy and 50 percent flux. In terms of mass, this equates to around 90percentage alloys and 10percentage fluxes systems. During the resistance spot welding, the fluxes system removes environmental contamination from the soldering connections. The capacity to remove environmental contamination is controlled by the action potentials. The soldering solution metal alloy must be either lead-based austenite or near-eutectic (SnPb or SnPbAg) or lead-free (SnAgCu whereas Ag 3 – 4 percent, Cu 0.5 – 1 percent). Since washing underneath the connected BGA may be problematic, a “no-clean” solder solution was suggested. The solution should be adequate for producing the soldering stencils apertures measurements; Type 3 pasted is suggested for ball pitches of 0.80 mm and 0.65 mm, while Type 4 glue is suggested for ball pitches of 0.5 mm. Soldering paste has age, weather, and moisture dependent. Make sure to follow the pasted company’s treatment instructions.

Placement of Components

BGA packages must be precisely arranged according to their shape. Individually placing the packets is not advised. Sophisticated automated element placement devices with computer vision achieve element positioning levels of accuracy of 50 m. Both PCB, as well as the parts, were visually scanned in these systems, and the parts were put on the PC Board in their predetermined places. These fiducials on the PCB are now either positioned on the PCB’s edge for the whole PCB or particular mounting points (local fiducials). A visual interface detects them instantly before the installation procedure. A sophisticated vision algorithm identifies the packets, allowing for the exact alignment of the full program.

Due to the increased surface pressure of the soldering, packets with conductive spheres as the BGA have had the advantage of self-alignment during the reflow process if they have been significantly misaligned. As a rule of the thumb, the maximum allowable element movement equals 30% of the metallic pads thickness just on PCB (for non-solder mask defined pads). As a result, for BGA modules, the soldering contact to PCB pads mismatch must be higher than 150 m (higher than 100 m for spacing 0.5 mm) to provide a strong installation procedure. This is often possible with a broad variety of finding the most appropriate.

The subsequent statements stand necessary:

  • Particularly on big boards, localized fiducials near to the gadget might mitigate a substantial number of PCB limitations.
  • It is advised that you utilize the positioning system’s ball identification abilities rather than the outlining centered. This removes the program’s soldering ball to packaging edge limitations.
  • Effective illumination and the right selection of measurement modes are required to guarantee the visual state’s recognition of the items. The precise parameters may be obtained from the device instructions.
  • Excessive insertion force might result in pushed-up soldering paste and solder junction failures.

Solder joints

To a considerable degree, soldering influences the production and accuracy of component manufacturing. In principle, all typical reflow soldered procedures are applicable.

  • compelled circulation
  • during the gaseous stage
  • far-infrared (with restrictions)

The specified temperature patterns were suited for BGA board manufacturing. During the soldering procedure, each soldered joint must be subjected to temps beyond the soldering solubility limit for a good amount of time to get the best soldering joint integrity, while overheating the PCB and its elements must be prevented. For the highest product normal temperature, please see the barcode scanner labeling on the packaging.
Special attention may be required when utilizing ultraviolet ovens lacking ventilation to ensure suitably uniform temperatures profiles for all solder connections on the PCB, particularly on big, complicated boards with varied heating capacities of the elements, particularly with someone underneath the BGA. Forced convective routing protocol has been the most commonly suggested kind. Although a nitrous environment can increase solder connection quality generally, it is usually not required for solder tin-lead metal alloys.

Gathering on Both Sides

In principle, BGA packages are ideal for installation on double-sided PCBs. Be cautious that items with a high weight may fall off throughout the final soldering process procedure when facing down during the PC Board assembly. In such circumstances, the packages must be constructed during the final (= second) reflow procedure. A weight restriction of 0.2 g/mm2 soldering surface (NSMD pad) might be considered as a rule of thumb. Whether boxes are impacted is determined not just by mass, but also by vibration and air draught in the heating chamber.

Solder Alloys Interoperability

Because various solder alloys may be used for packaging spheres or bumping and soldering paste placed just on PCB, the interoperability of these compositions must be considered.

The benefits of BGA boards

Dense population

A BGA solves the difficulty of making a tiny packaging for a semiconductor technology with thousands of connections. Pin grids displays and dual-in-line surfaces mounted (SOIC) modules were being manufactured with an increasing number of connections and reducing distance amongst the connections, but this was producing problems with the soldered procedure. The risk of inadvertently crossing neighboring connections using soldering increased as packaging pins became closer apart. If the soldering is put to the packaging at the manufacturer, BGAs don’t have this issue.

Convection of heat

The decreased temperature difference across the container and the PCB is another benefit of BGA packaging over packaging with separate connections (i.e. boxes with legs). This permits heat produced by the semiconductor technology on the inside of the packages to transfer more freely to the PCB, reducing overheating of the chip.

Connections with low capacitance

The smaller the undesired capacitance of an electromagnetic wire, which causes signal distortions in high-speed electromechanical equipment, the smaller it is. Because of the slight distance between the packaging and the PCB, BGAs have consistently low inductors and so outperform pinning gadgets in terms of electromagnetic efficiency.

Problems with BGAs throughout PCB manufacturing

While research, soldering BGAs into place is impractical, therefore sockets are utilized instead, however, they are unstable. There seem to be two main types of sockets: the more dependable version features springtime pins that force up beneath the balls, but it doesn’t permit for the use of BGAs with both the balls detached since the springs pins might have been too shorter.

Interested to know more about BGAs or pcb assembly services? Email PNC at sales@pnconline.com

What is High TG In PC Board Fabrication?

The making of PCB involves different steps, technologies, and terms, and TG is one such term that refers to the Glass Transition Temperature. High TG PCB is the board made at a high temperature. We will discuss this topic in detail, including the TG value, features, applications, materials, parameters, and much more.

What is High TG PCB?

If a PCB’s temperature goes beyond a set TG value, its condition will change. Like, the solid board will turn rubbery, affecting a PCB’s function. Depending on where you use a PCB, the temperature of the application should be at least 10 to 20C less than the PCB temperature.

Understanding TG Value

TG means Glass Transition Temperature like there is a certain limit of this temperature for PCB and that specific temperature is the TG value. TG value helps in understanding the PCB material, and you can find which temperature is required for its service.

Secondly, it helps you to find the condition of the PCB material, like if it’s solid, flexible, or solid-flex.

High TG PCB and Its Features

You have to choose a high TG Printed Circuit Board for your application carefully, because it involves multiple features, including thermal, electrical, mechanical, and chemical features.

Thermal Features: they include the TG or Glass Transition Temperature, thermal conductivity, thermal temperature’s coefficient, and decomposition temperature. TG is the temperature at which the state of the PCB material changes. But, when the board cools down, it gets back to its initial condition.

Electrical Features: they include the surface resistance, electrical power, volume relativity, and the dielectric constant and loss tangent.

Chemical Features: the chemical properties of a high TG PCB include the moisture absorption and the methylene chloride resistance of the PCB material. The TG PCB should be able to resist moisture if it’s near water.
Mechanical Features: the mechanical features are also important to know regarding the TG PCB. They include the flexural and peel strength, and the young’s module.

Suitable Materials for High TG PCB

A PCB has two materials, including laminate and substrate. The substrate includes epoxy resin, glass, or paper weave. The substrate should be compatible with the TG. Some common substrates that we use for a high TG PCB are;

  • CEM-1, 2, 3,4, and CEM-5
  • G-10 and 11, FR-1 to FR-6
  • Aluminum
  • Knapton
  • Pyralux

The last three materials are flexible.

The laminates should also be compatible with your TG PCB in terms of strength and temperature. Some common laminates are:

  • FR-1, and FR-4
  • CEM-1, CCEM-3
  • Teflon

Criteria for High TG PCBs

Printed circuit boards with a high TG value are based on certain criteria as described below:

  • The selection of a PCB, depending on the components like it can be single or double-sided PCB or embedded.
  • The stack-up PCB with a single layer or several layers
  • The design of such boards can be based on a module or it can be custom
  • The strength of the board also matters, like it should be robust either electrically or mechanically
  • PCB’s bendability also helps to classify the TG PCB, like if it’s hard, flexible, or hard-flexible
  • The electrical strength also helps classify the TG PC Board

Generally, manufacturers use bendability and strength to classify a TG PCB‘s physical properties.

Where Can You Use The High TG PCBs?

You can use the high TG circuit boards in intense conditions, as the environments with high-vibration devices. They are also suitable for applications with shocks, chemical components, and high temperatures. Like, missiles and car parts often come up with chemicals. So, the suitable industries for high TG PCBs include aerospace, telecommunications, military and defense force, automobile, and down-hole drilling.

What to Consider While Designing a Rigid PCB?

You must hire a professional PCB manufacturer for the right design, manufacturing, and assembly of these boards. The engineer must know the kind of environment that suits a TG PCB to function precisely. Below are a few examples to help you understand it.

Commercial Use

Many telecommunication companies use the best materials for mobile devices to enable them to bear high shocks. Like, the phone should not get damaged easily when you drop it.

Auto Industry

PCB has to be safe under a car’s hood as it’s mostly vibrating, so a shock or crash might happen. Hence, a rigid PCB is the best solution in this case.

Aerospace Industry

The flying machinery always needs the high TG PCB because there is intense vibration, like in the jet engine, as there are thousands and millions of micro-vibrations in one minute. So, equipment related to aerospace should be able to tolerate extreme temperatures, like from -45°C to 85°C.

Other Applications

These boards are also ideal for solar power equipment, such as power inverters and cogeneration equipment. As these boards resist temperature, they work well in many industries. Like, one of its applications involves Lead technology, like the medical, computer, and telecommunication industries.

The TG PCB is also used in broadcasting, like booster stations. Besides, the fire detectors and burglar alarms also need such boards.

Use of High TG Flex PCB

It is clear from the name that a flex PCB can adapt any design or shape to get compatible with certain products. Like, they can tolerate intense environments better than rigid PCBs. You can use the high TG flex PCB in defense and military, aerospace, medical equipment, consumer electronics, auto, wireless networks, as well as industrial equipment.

What To Consider While Designing a Flex PCB?

You must hire a professional PCB manufacturer for the right design, manufacturing, and assembly of flex PCB. The engineer must know the kind of environment that suits a TG PCB to function precisely. You should see if:

  • You need a flex PCB for an ordinary environment or an extreme environment like an explosion. Whereas the cell phone has a normal environment.
  • The environment should be free from any moisture before installing a high TG circuit board.
The Design Process

The design of a high TG PCB involves different steps, such as

  • Using the right software, like CAD, Eagle, Altium Designer, etc.
  • You must know the power requirements to suit different components on the PCB. You should also consider a specific plan for noise reduction caused by a TG PCB.
  • Preparation of the stack-up plans documents as it is essential for making the best TG PCB.
  • The floor layout for a PCB with proper sections, including components. Like you can place them together or separately.
  • TG PCB should be complete in terms of a power plane and ground details. These details ensure proper routing for signals.
  • The board should be compatible with patterns in terms of sizes. All components should be well-placed to help a PCB function the right way.
  • It is important to design routs for high-frequency signals, as the route should be clear for a flawless signal transfer. This step involves vias, as they help in proper signals. You need the reverse via and signal via in this case.
  • You must follow the 3W-rule to increase the traces’ distance which helps to reduce the coupling effect.
  • Another rule to reduce the coupling effect is the 20 H rule.
  • In the end, check the routing guidelines to see if you are doing everything the right way.
Specs and Design Parameters

The fabrication of a high TG PC Board Fabrication involves certain parameters and specs, depending on the application. Some standard parameters are described below.

How Many Layers Do You Need

Designers prefer the even number of layers while developing the high TG PCBs. But, the odd numbers of layers are also suitable in certain applications.

Dimensions of PCB

The PCB dimensions depend on its application. Like, you need a large circuit board for a broader application. Besides, there should be enough space on the board to place the electrical components.

Well-Finished

The high TG PCB should be well-finished, and the material depends on where you want to use this board. Like, some common materials are;
HASL, or hot air leveling – It is ideal as it is cheap and can be stored for longer.
OSP, or organic protective surface
Immersion silver – It gives a smooth surface, and it is cost-effective. It has many storage limitations
Immersion tin – It suits the SMT

Immersion gold – It can be stored for longer with a few limitations.

ENEPIG, nickel palladium – It can be stored longer, but it involves a complex process.

Solder mask – It protects the PCB from environmental elements.

Weight of copper – You must also consider the weight of copper like it includes both initial and finishing copper. Generally, the weight is 1 oz. to 1.5 oz. or 5 oz. It also depends on the layer and board thickness.

Assembled PCB thickness – The TG PCB thickness depends on its material and type. Like, if it’s flexible, hard, or a hard-flex board.

Distance between layers – The distance or spacing of electrical components and layers should be equal for high-frequency signals. As it reduces the coupling effect.

Via sizes – The drill aspect ratio and the hole size should also be appropriate. Generally, the PG PCB can have either plated-through or non-plated through holes, depending on the placement and layout design.

Board quality – The board should have a high-grade material to ensure an effective function during application. Besides, you must check the quality of the TG PCB to evaluate its performance in terms of specs. Like, you should test its lamination, vias, copper plating, solderability, finishing, components, and cleanliness.

Interested to know more about PCB TG or PCB Assembly? Email us at sales@pnconline.com

PC Board Fabrication, V-Scoring-Purpose and Benefits

PC Board Fabrication, V-Scoring-Purpose and Benefits

PCB or a printed circuit board has different holes, cuts, and elements, and V-scoring is one of them. V-scoring pre separates the PCB and designers also call it V-groove because a groove resembling V is cut on the circuit board’s top and bottom. Generally, the depth of the groove is 1/3 of the board depth and there is a thin layer between two Vs for the board processing.

The boards with V-grooves are either end to end or side by side with adjacent edges. The groove helps break boards with a little force, and you can divide a single panel into several parts with the help of V cuts.

Purpose of V-Scoring

Manufacturers use V-scoring while combining an array’s circuit boards for an effective assembly. It makes the assembly process less hectic, and you can easily set apart the assembled PCBs.

V-scoring helps to reduce pressure during the placement of SMD components on the circuit board by an SMT machine, and while separating the assembled PCBs.

The PCB panel helps manufacturers to insert the components at a high speed, using one panel at a time, rather than one circuit board.

The panel boards are loaded with their parts through an automated machine that performs the pick-and-place function.

These uses motivate PCB engineers, manufacturers, and buyers to use the V-grooves.

Specifying V-Scoring

Engineers specify V-scoring according to the groove depth, or a distance between the two grooves or Vees through a cross-section. The residual material in this case is known as Web. Each measurement has to be equal, including 1/3rd on the top, bottom, as well as a 1/3 web in the center.

The practice of the 90 degrees or the 30 degrees scoring is also there in some cases. However, the 90 degrees scoring is easy to break compared to the 30 degrees scoring.
You can alter these measurements according to your needs, depending on the array size and the ease of separating the boards later on.

You have to use a 30-degree cutter for a score-line cutting with a certain depth. You can calculate the rest of the web based on the material thickness. However, the tolerance of +/- .002″ is essential in this case.

When to Use a Jump Score

Jump score is used in some conditions though it is not that common. In jump score, the score does not go from one end to another, instead, it ends before the circuit boards end. Like, the cutting blade stops before another end comes. The jump scoring provides a firm array while assembly.

Some V-Scoring Terms

There are certain terms to consider while making PCBs with V grooves, and we will discuss them one by one.
• PCB board has some borders or extra material that helps in making a panel, and they are called Rails or Waste Tabs. They enhance a panel’s mechanical strength, allowing an extra material or borders that help to clamp a panel while assembling.
• Another term used in V-scoring is Fiducials which are marks being etched on the borders or a PCB’s inner surface, like on upper and lower layers of copper. Fiducials help the SMT assembly to identify the position of the PCB and SMD components.
• The other important elements are tooling holes located on a PCB’s four corners. The manufacturers use these holes to align a PCB during drilling and routing. Like, the alignment that involves the SMT carriers, solder plate printing, and PCBs’ final assembly.

Process of V-Scoring

It involves two blades being beveled at 30o, or 45o, or 60o, and the blade resembles a wheel with several gears or knives that make V-grooves. Both top and bottom blades rotate while cutting. When the PCB assembly is over, an individual assembly of the board occurs by dividing the sub panels.

Rules To Follow In V-Scoring

Some fabricators think that the perfect size of the board is compatible with an 18”×24” sheet of CCL, but this is not so. Because the fabricator has to use some part of the sheet while processing. Both customer and manufacturer should discuss the kind of a PCB they require, besides, it should be the best.

Some Rules for Exceptional Circumstances

1. There should be zero space between two circuit boards
2. If you opt for V-scoring, your PCB’s size should be at least 75×75 mm, and it can go up to 450 x1250 mm. So, the scoring won’t be successful if the board size is not as per the rule.
3. Make sure the V-scoring path or line is straight, whether it’s continuous like end to end, or discontinuous like jump scoring.
4. For a perfect V-groove, the minimum thickness of the board should be 0.6mm.
5. You can choose the groove angles from 30o, 45o, or 60o.
6. The space between the PCB edges and parts should be a minimum of 6.35 mm
7. The minimum distance between the PC Board Fabrication outline and V-grooves’ line has to be 0.35mm.

Benefits of V-Scoring

• V-scoring helps to use a PCB surface effectively
• It helps reduce the manufacturing cost by fabricating many boards on one PCB.
• It helps to place more than one circuit through one assembly, helping in precise sub-assembly.
• V-scoring tools are cost-effective, portable, and require minimum maintenance.
• It helps save time as it allows you to separate different parts from a final assembly.

Drawbacks of V-Scoring

There are some restrictions of V-scoring like it is not suitable for PCBs with components placed near edges.
V-scoring can affect the PCB structure, reducing its strength due to the mishandling of a solder machine. However, fabricators apply jump scoring to maintain a PCB’s strength. You can read the above section to understand the jump scoring.
In the case of V grooves, you have to allow a 0.05 inches clearance between the grooves and components. The blade should not come between the components, especially for taller parts. Likewise, you should keep enough clearance for components located on the wide connection surface.

Difference Between PCB Scoring and PCB Panels With Tab-Routing

The PCB design determines if you should choose V-scoring or tab-routing. However we have a guideline for better selection, but you have to follow it.
1. The circuit board shape helps to select the right scoring. Like, V-scoring is suitable for rectangular or square PCBs, whereas the tab-routing goes well with an irregular shape.
2. You should choose a tab-routing if the components are hanging on the PCB edges. Besides, the tab-routing does not affect the edge quality. Whereas V-scoring makes edges rough.
3. V-scoring works faster than tab routing, besides, it is cost-effective than tab-routing in terms of labor.
4. At the same time, there is less wastage of material in V-Scoring compared to the tab-routing, which also reduces the total cost.
5. It also depends on the number of boards in an array and the number of PCBs in both directions, including the X and Y planes.

Frequently Asked Questions

What Is The Difference Between The PCB And PCBA?

The process is the same, but it involves two stages. Like, PCB is just a circuit board with components, whereas PCBA is an assembled board with necessary components, and it is ready for application.

What is Jump-Scoring and Its Use?

Jump scoring involves a cut that starts from one end of PCB but it stops before the other end, unlike V-scoring. Jump scoring strengthens a board for multiple processes.

What Is Tab-Routing In PCBs?

Tab routing helps you to process different circuit boards on one panel. It also helps you to isolate boards by breaking the tabs that exist between various boards.

What Is The PCB Penalization?

A process of connected small boards in a single array is called the PCB penalization. It helps fabricators to move the circuit boards while assembly.

What SMT Stands For In PCB?

SMT stands for Surface Mount Technology, and it’s a process of installing the electrical components on the PCB directly. Whereas the component installed through SMT is known as SMD or Surface Mount Device.

Final Thoughts on V-Scoring

PCB fabrication becomes economical by adopting cost-effective processes, including V-scoring. The boards with V-grooves are either end to end or side by side with adjacent edges. The groove helps break boards with a little force, and you can divide a single panel into several parts with the help of V cuts.

It involves less routing space, so you can add several rows in the PCB panel to be fabricated. It eliminates the wastage of the laminate, besides, V-grooves also save money and time by streamlining the PCB processing and manufacturing.

V-scoring helps to reduce pressure during the placement of SMD components on the circuit board by an SMT machine, and while separating the assembled PCBs.

V-scoring tools are cost-effective, portable, and require minimum maintenance. Moreover, it helps save time as it allows you to separate different parts from a final assembly.
But, V-scoring can affect the PCB structure, reducing its strength due to the mishandling of a solder machine.

Interested to know more about V-scoring or PCB assembly services, email us at sales@pnconline.com

Castellated Circuit board fabrication (Uses, and Design Guide)

Castellated Circuit board fabrication (Uses, and Design Guide)

Electronic goods are increasing with a time that demands smart, high density, and multifunctional PCBs. You will see smarter PCBs than in the past as their geometric index is continuously increasing. Advanced PCBs with reduced sizes need to have updated soldering with a better electrical connection. Large holes result in poor connections, affecting a product, hence, the hole size has reduced to half.

PCB’s need different holes for connections and one of them is plated half hole and designers also call it a castellated hole. It is a drilled hole finished in copper and it exists on the board boundaries.

As holes are semi-plated, so we call them plated half holes. These holes help mount one PCB to another and simplify the assembly of PCBs. The hole looks like a broken circle and enhances the PCB’s soldering. In other words, plated half holes help in board-to-board soldering.

You can enhance various Printed Circuit Board modules through castellation, including Bluetooth or a Wi-Fi module. You can install these modules together during soldering. The castellated holes can directly connect two circuit boards, creating connections between the board and its module.

You can apply these holes in different displays, high frequency, as well as ceramic modules that need soldering to a standard board. Remember that this technology is not compatible with single-layered PCBs.

The boards with semi-plated holes can benefit different industries, including power, computers, consumer electronics, automobiles, and telecommunications.

PCB fabrication of PCB Castellations

PCB has to go through a certain process for plated half holes, and it involves a certain order. So, let’s look at all the manufacturing steps.

• Holes drilling process
• Castellated hole making
• Making of panel plating
• Image transfer
• Pattern plating process
• Stripping is done
• Etching process
• Solder masking process
• Surface finishing
• Implementation of castellated holes

Stacking Of PCBs through Plated Half Holes

The use of plated half holes for stacking of two PCBs involves two criteria, such as

• First, the circuit boards must have an electrical contact, as just a physical connection won’t work. So, both PCBs should have electrical connections.
• The boards should be tightly placed without any space between them. Even a little space between the boards will result in incomplete or wrong soldering.
The semi-plated holes technology is cost-effective and effectively changes a PCB into a surface-mounted assembly. As PCBs are plated and concave, so they offer an excellent soldering base. Mounting of one PCB over another involves a zero distance between them, so plated had holes are best because they lie on the board edges. Besides, dust won’t stay between two PCBs, providing flawless connections.

Uses of Plated Half Holes in PCB

Half holes or castellated holes are located on the circuit board’s edges and resemble several PCB parts. There are different ways to use these holes, such as:
• PCB with plated half holes serves as a breakout board for bigger circuit boards.
• These holes help you to have a custom design of the component like you can alter the pin layout according to your needs.
• Castellated holes help manufacturers to install one PCB to another without any hassle.
• These holes join two circuit boards without leaving any void between them, helping in precise soldering.
• Plated half holes help you to develop a single PCB based on integrated modules. The board is ready for another assembly through its modules.
• The Wi-Fi modules and breakout PCBs also depend on semi-plated holes. Moreover, these holes help you to develop wireless connections between PCBs.
• These holes also help engineers to use complex components with a breadboard which is often a great challenge.

• Castellated holes allow you to reuse the IC without any fear of the damage that happens in direct usage.
• The holes help to work easily with leadless components, such as LGA, QFN, BGA, etc. during SMT assembly
• Small PCB with castellated holes act as subcircuits for large boards containing inverters or filters etc. They are compatible with multiple modules, including GOS, GPRS, GMS, and several other smart modules.

Guidelines for Making Plated Half Holes

You have to consider some design parameters for PCB soldering with castellated holes. There are some guidelines to follow in this case, including diameter, distance, size padding, surface finishing, etc. You can successfully use these holes by following the below parameters.

Holes Diameter
PCB is either advanced or standard and castellated holes are compatible with both. In the case of a standard PCB, the diameter of a hole should be at least 0.6 mm. whereas, you can keep it lower than 0.6 mm in advanced PCBs.

Holes Distance
On the other hand, the distance between two half-plated holes should be at least 0.55 mm. Make sure it is not less than this figure, as it would hinder the soldering.

Surface Size
The surface for making castellated holes for a PCB mount should be large enough. Small size won’t let you keep enough distance between the holes.

Surface Finishing
You must well prepare a surface for PCB mounting like you can do it through an ENIG finish as it is more practical. But, the purpose of PCB also helps to determine the right finishing material.

Suitable Pads
You must use heavy pads as they help join two castellated PCBs without any flaw. There should be a minimum number of holes while using them for soldering, as it can enhance PCB assembly and alignment. Whereas the circuit board’s design also determines the number of holes it should have. But, you can reduce or increase this quantity according to your requirements.

After following the above guidelines, the mounting and assembly of boards would be simple and flawless.

The Design of Plated Half Holes

In terms of design, castellated holes are developed in different styles, such as
• Half holes
• Half holes with small cuts
• Holes with small leads for connectors
The design process involves drilling and copper plating, but via is not like normal PCBs, instead, it is smaller than a standard hole. The micro vias diameter is less than 150 microns, and you can make them using laser technology or a mechanical technique. The laser technology is more convenient in developing a PCB and a small via ensures more output.
You can select any process that suits your PCB, and once the holes are ready, they are cut into half, resembling a semi-circle that’s why we call it a half hole. The holes opening is always on the PCBs edges.

Indicating Plated Half Holes In PCB Design

Different software brings different designs for holes, however, the Gerber files include specific results. You can add a hole directly on the edge of the board, then can cut it across. So, make sure the half portion of the hole is on the PCB, and half is on another side of the outline.
It should include;
• The GTL copper layer and a GBL copper layer, which are copper pads for both upper and lower layers for every half hole.
• Solder mask layers, including the GBS and GTS, and openings for a solder mask on both sides.
• Each plated hole requires drilling that involves a drill layer, including DRL and TXT.
• Likewise, the mechanical layer should cut the drill hole. This layer includes the GKO and GML.
But, you should consider what your design software offers in terms of documentation.

Cost of Plated Half Holes
The manufacturing of plated half holes involves more work and time, and you need to do every step with care. So, a PCB with these holes becomes expensive than standard boards. However, the cost also depends on the design, your requirements, and a circuit board’s size.

Certification
Plated half holes should be certified, depending on the country of manufacturing. Like, it should be RoHS-certified in the United States. A certified board ensures a high-quality product that you can trust in terms of application.

Frequently asked questions

What Is The Difference Between Plated And Non-Plated Holes In PCB?

Plated holes are finished or plated in copper, whereas non-plated holes are without copper finishing.

Why Do PCB Vias Require Plating?

PCB connects different layers on the PCB, providing a path for electrical signals. Your product won’t work without connectors, so vias are essential.

Can You Use Plated Half Holes For A Single-Sided PCB?

No, a single-sided PCB has a single layer, whereas half holes are suitable for more than one layer as they help join two PCBs.

Can The Number Of Drills Affect The PCB Cost?

Fabrication of PCB requires holes through drilling, and more holes mean more drilling. If the number of drills is more, it requires more time to complete, hence, it will increase the manufacturing cost. So, the total cost of PCB will also increase. However, you will have to consider this factor for bigger PCBs as small boards are cost-effective.

Final Thoughts

PCB needs different holes for connections and one of them is plated half hole and designers also call it a castellated hole. It is a drilled hole plated or finished in copper and that exists on the board boundaries.

The boards with semi-plated holes can benefit different industries, including power, computers, consumer electronics, automobiles, and telecommunications.

Interested to know more about Circuit board fabrication of castellated holes. Email us at sales@pnconline.com