Tag Archives: SMT assembly

PC Board Color- Choosing Your Desired Color

PC Board Color- Choosing Your Desired Color

PC Board, PC Board fabrication, Printed Circuit Board, SMT assembly, , ,

PC Board come up in different colors of which a green solder mask is the most common one. You will see most circuit boards with green solder masks. But, the industry is getting innovative due to changing technologies, so designers try new colors to make printed circuit boards.

PCB Solder Mask

Before getting into PCB colors, you should know what the solder mask is? The printed circuit board has different layers, and the top layer is the solder mask, whereas the bottom layer is the copper foil. The purpose of the solder mask is to cover the bottom layer from getting polluted or oxidized. The main material of solder masks is often the insulating resin which is printed on the circuit board’s unsoldered areas. The resin protects the board from heat, moisture, and any kind of damage.

Printed Circuit board Fabrication

You can customize a circuit board in terms of solder masks and other elements. According to research, 99% of solder masks are green. However, other colors are also emerging, such as red, black, white, yellow, blue, and purple. These colors are used for different applications. Such as RDs at the NPI stage are often made red. Whereas white is used for LED light circuit boards.
Each PCB color has some good and bad aspects that we will discuss here.We will also help you choose the right PCB color according to your application. Let’s start with the colorgreen.

Green Solder Mask In PCB

Though many colors are there, the green solder mask is still at the top as it helps to visually inspect the PCB to find any defects. Moreover, green makes a good contrast with the white silkscreen, helping you to remove the flux residue. If you don’t know how to select a color for the solder mask, go for green right away.

PC Board Color- Choosing Your Desired Color
PC Board Color

Red Solder Mask In PCB

Red is another color for PCB solder masks,and it adds brightness to the PCB. Red has a nice contrast with planes, areas without copper, and traces. However, the contrast is less than a green circuit board.
You may need a magnifier to find any defects in the traces. However, the red solder mask is compatible with screen printing and also helps remove residual flex like a green solder mask.Red also enhances a device if the circuit board is visible.

Blue Solder Mask In PCB

PCB with a dark blue solder mask is also popular. It hasless contrast with the planes, traces, and no-copper surfaces.Hence,you have to use a magnifying glass to inspect the construction defects. But, it has a high contrast with screen printing that makes blue suitable for a PCB with several components.
But, blue is less clear than green and red, and it highlights the dirt that makes it hard to remove the flux residue. A bluesolder mask is ideal for boards with hidden routes. It is also compatible with Arduino open-source tasks or products.

Black Solder Mask In PCB

A black solder mask is not so ideal in terms of inspection, as planes, traces, and no-copper surfaces have less contrast. Other than a strong magnifier, you also have to rotate the light to create a shadow to highlight the trace.
However, there is a good contrast of screen printing, and it’s visible on the board without any lights and so are the pads.But,the black solder mask has a high heat absorption during reflow. You have to place a temperature checker near the board while manufacturing. Moreover, the screen printing gets light brown during reflow due to the board’s high heat absorption.
The dirt also gets more prominent on the black surface, making it hard to clean. That’s why the manufacturing of a black PCB board involves more cost than other colors. On the other hand, black is ideal for LCD panels.
The black solder mask has two types, including matte and gloss of which matte black contrast is better than the glassy black.However, a black solder mask gets soiled and it becomes hard to repair it.

White Solder Mask in PCB

White solder masks have the lowest contrast than other colors, and placement of the marks becomeshard evenif they are under lighting. Whereas the cleaning of a white Printed Circuit Board is so difficult that you can’t imagine. You have to do so much effort to remove the stains from a white PCB.
However, it has some benefits as black printing on a white PCB creates a good contrast. You can use a white solder mask in LED applications where the front panel has to be white to increase the brightness.

Yellow Solder Mask in PCB

Yellow PCB is as good as green because there is a high contrast between theplanes, traces, and no-copper surfaces. You can use the dark yellow mask to enhance the routes, making them prominent.
There is one disadvantage of using a yellow solder maskand that is it’s less contrast with the white silkscreen. Many manufacturers prefer a black silkscreen with a yellow solder mask, even though it is less satisfactory.
It is easy to clean the residue from a yellow solder mask.So, yellow can be a great choice even though some people don’t like a lively color like this.

Purple Solder Mask in PCB

Purple PCBs are rare, however, advanced devices can have such boards. Purple has good contrast with the traces and planes. However, it does not go well with white silk printing. But, a purple solder mask would look great with an immersion gold surface, creating a good match.
So, you can choose any of the above colors to customize your PCB, depending on your requirements.
Why Should You Use Different PCB Colors?
It is not enough to know that PCB has different colors, because one should also know its reason. There are a few reasons behind using different PCB colors instead of just green, such as:

  • Different PCB colors help engineers indicate the revisions and changes to help users recognize them.
  • The application of other colors in PCBs can create better contrast. You have to understand the importance of the assembly tools in terms of transmission light, reflectance, and absorption.
  • Different PCB colors can reduce the errors caused by a mixed assembly. Moreover, the contrasting colors help decrease lead-free meetings.
  • The colors of the printed circuit boards are known as PCB codes. You would see modern PCBs in different colors compared to traditional boards. Even today, the PCmotherboard’s color is green epoxy because of its qualities
  • Though the colors of the PCB solder mask don’t influence a board’s performance, they can enhance its resolution. However, solder masks with clear transparency have a high resolution. The yellow and black PCB resolution is less than other colors like green, red, and purple.

Hope the above discussion helped you understand different PCB colors along with their advantages and disadvantages.

FAQs

What Is PCB Solder Mask?
The printed circuit board has different layers, and the top layer is the solder mask, whereas the bottom layer is the copper foil.
How Many PCB Colors Are There?
PCB comes up in several colors, such as green, red, black, white, yellow, blue, and purple.
What Is the Green Solder Mask?
The green solder mask makes a good contrast with the white silkscreen, helping you to remove the flux residue.
Is Red Solder Mask In PCB Effective?
Yes,the red solder mask has a nice contrast with planes, areas without copper, and traces.
What Is The Reason Behind Different PCB Colors?
Different PCB colors help engineers indicate the revisions and changes to help users recognize them. They reduce the errors caused by a mixed assembly. Moreover, the contrasting colors help decrease lead-free meetings.
Why Engineers Don’t Prefer Black Solder Mask?
A black solder mask is not so ideal in terms of inspection, as planes, traces, and no-copper surfaces have less contrast. Moreover, it gets dirty and is hard to clean.
Where Can I Use A Purple PCB?
The purple solder mask is compatible with an immersion gold surface, as both match very well.

Wrap Up

The green solder mask is the most common in circuit boards due to its high contrasting ability. The purpose of the solder mask is to cover the bottom layer from getting polluted or oxidized. The main material of solder masks is often the insulating resin which protects the board from heat, moisture, and any kind of damage.
Many users customize a circuit board in terms of solder masks and other elements. You will see various PCB colors in different applications, such as RDs, LEDs, PCs, etc.
Would like to know more about PCB Colors or smt assembly? Email us at sales@pnconline.com

Flexible Circuit PCB Assembly

Flexible Circuit PCB Assembly

PC Board, pcb assembly, pcb assembly services, PCB Design, Printed Circuit Board, printed circuit board assembly, SMT assembly, , , , , ,

It can be tricky to figure out what you need to know about flexible circuits assembly, especially since it’s not something many people are familiar with or have experience with. Flexible electronic assembly is one of the most innovative and useful circuit boards in the electronics world since it allows you to make low-profile electronic devices with multiple electronic components.
The Circuit board has different types, including a standard or rigid PCB, a flex PCB, and a flex-rigid PCB. Besides, these circuit boards are further divided into single-layer PCBs, double-layer PCBs, and multilayer PCBs.
A flexible circuit board has a flexible base, but the components are just like a rigid circuit board. However, you can turn a flex PCB into any shape while using it which means it is easy to bend.The following article will help you learn everything you need to know about flexible smt assembly so that you can get started working on your designs right away.
Before we move to the assembly of a flex PCB, we want to discuss its applications.

FPCB Applications

The FPCB is a vital part of electronic products that we use daily, such as desktop printers, hard disks, and several other devices. You would see the use of a flex circuit board in the below industries.

  • Medical industry
  • Consumer electronics
  • Communications industry
  • Military
  • Automotive industry
  • Aerospace industry
  • Transportation

Engineers use it in the transportation industry because flex PCBs are vibration-resistant and constant movement for several hours can’t damage them.

Choosing The Right Material And Processes

When it comes to choosing the right materials and processes for your flexible circuit board assembly, there are a few things you need to keep in mind.
First, consider the environment in which the board will be used. Will it be exposed to harsh chemicals or extreme temperatures?
Second, think about the amount of flexibility you need. The more flexible the circuit, the more expensive it will be. Finally, consider the size and weight of the finished product.

What Are The Uses Of The Flex PCBs?

Every kind of circuit board has specific uses because it is an important part of different products, especially electronics. Designers preferflexible circuit boards for computers, mobile phones, and servers to make them more effective, less heavy, and more flexible. Though different devices have different shapes, functions, and sizes, they all include flexible circuit boards.
Let’s look at the main uses of flexible Printed Circuit Board
1-FPCB is Flexible

  • The flex circuit board is an elastic board that helps in placing it near folds or edges.
  • It is suitable for 3-axis connections due to its elasticity.
  • FPCB involves minimum wiring, whereas some applications don’t require any wiring at all. So, there are no wiring issues that make a device more reliable.

2-Flex PCB Reduces Weight and Space
Unlike rigid circuit boards, a flex PCB needs less space. According to engineers, it can save 60 percent of space, hence, its weight also decreases.
3-Flex PCB Reduces Connectors
If you use a flex PCB in a 3D design, it will eliminate or reduce connectors. Whereas the bending cycles go up to 200 000.
4-FPCB Eliminates Vibration
A flex PCB is very light which helps it absorb movements or vibrations. So, the vibrations can’t damage an FPCB. Moreover, the solder joints also stay safe.
5-Compatible With Tough Environments
You can use a flex circuit board in tougher environments due to its material. Its main materials are water-resistant, shock-resistant, heat-resistant, as well as corrosion, and oil-proof.
6-Thin layers
Flex PCB has thin layers on the inside which reduce its weight. The copper layers in an FPCB are heavy which if combined with thin layers becomes useful for high-power applications.

Types of Flex Circuit Board

A flex PC Board has different types, including single-sided, double-sided, multilayer flex, and rigid-flex circuit boards. Let’s look at their pros one by one.
Single-sided F PCB: It is economical, flexible, and has many bending cycles.
Double-sided F PCB: Its design is more flexible than others. Moreover, it saves space and provides dual-sided soldering.
Multilayer F PCB: It is lightweight and compact and its flexibility is more in a 3D design. It is compatible with blind and buried vias.
Rigid-flex circuit board: It helps have a long-lasting 3D application having stable parts, pins, heat streaks, etc. It reduces noise and enhances signal integrity.Besides, it is more reliable and offers better impedance.
It helps have minimum mechanical space and reduces the weight of the device. It is compatible with the HDI micro-via. It is economical and offers a flexible pcb design.
Some More Advantages
A flex PCB can give you many benefits, but mainly it enhances flexibility and saves space. Its assembly involves a few items that reduce its cost and manufacturing time.

  • A flex circuit board offers a high-heat dissipation.
  • It enhances the inner airflow.
  • It reduces the size and weight of the package.
  • It involves minimum assembly errors.
  • It reduces the inductance of wires.
  • A flex circuit board enhances the product’s looks.
  • The assembly time and cost of the FPCB are less in some cases.
Flexible Circuit PCB Assembly
Flexible Circuit PCB Assembly

Flexible Printed Circuit Board Assembly

The assembly of a flex PCB is the same as a rigid board except for a few changes due to certain technical needs. The assembly of a single-layer flex PCB consists of the following steps

  • BOM
  • Electrical testing
  • Punching process
  • FPCB baking process
  • Optical inspection
  • FQC process
  • Silkscreen printing process
  • Reflow soldering
  • Packaging process
  • Mounting process
  • Deep inspection

Flex To Rigid Surface
Since flex PCB is soft and gets deformed, it is hard to assemble it directly on SMT. So, engineers fix it on a hard surface such as a tray for the assembly process. The tray or a hard carrier should be well-intact to make assembly smooth.
Low-Density Assembly
Flex PCBs aremore costly than the rigid circuit board, so most of them are used for connecting different modules having different functions. So, the FPCB assembly involves fewer components in the case of low-density assembly. The quantity of the components ranges from 2 to 50 in this case.
Increased Panels
Manufacturers use many planes during FPCB assembly to enhance the process. A flexible circuit board is used in smart products, such as digital cameras and mobile phones, so a single board is too small. As it involves a few components, manufacturers use panels which are then removed through punching.
Use of Auxiliary Fixtures
Flexible PCB assembly involves auxiliary fixtures as it deforms easily. These fixtures include:

  • Baking fixture
  • Carrying tray for FPCB
  • Electrical and function test fixtures
  • Cutting Fixtures

High Demand for Quality
The devices with FPCB are used in an environment where the accuracy of control has to be high. So, the board components should be well-positioned to get compatible with a particular environment.One must focus on certain factors, such as anti-static precautions, cleanliness, and reliable soldering. It also involves several technical issues.
Increased Assembly Cost
A flex circuit board has a costly assembly compared to a rigid circuit board. It involves many fixtures which also increases its cost.Theassembly process takes more time than a rigid PCB. Moreover, the assembly involves lots of accessories and working labor because less equipment is used. Besides, the increased demand for high quality and flawless manufacturing environment also is the reason for the high cost.
However, as the flex circuit board’s application is increasing, so new technology and assembly methods emerge. Eventually, the assembly cost decreases due to less time and tools involved.
Choosing A Supplier
When it comes to choosing a supplier for your flexible circuits PCB assembly, there are a few things you need to take into account. First, you need to make sure that the supplier is reputable and has a good track record.
Second, you need to make sure that they have the necessary experience and expertise.
Third, you should ensure that they are able to meet your specific needs and requirements.
Fourth, you should see if they are able to provide you with a competitive price. Finally, you need to ensure that they can produce high-quality products at an efficient rate.
For example, some of the key considerations when selecting a supplier are quality control measures in place and their ability to adapt to changes in demand. To put this another way, if a company’s success relies on being able to keep up with production rates, it will be easier for them to fulfill orders if they’re accustomed to adjusting according to supply and demand than if they’re not. The same thing goes for quality control, as companies without established procedures may not be as adept at preventing defective products from reaching customers.

Final Words

Flexible circuits are used in a variety of products, from hearing aids to sports-related items like fitness trackers and smartwatches. They allow you to connect electronics into your home, and even onto your body, giving you easy access to valuable data and features. However, with all this flexibility comes the need for greater care in assembly than typical PCBs require. The designer must know about flexible circuits and PCB assembly to ensure the end product works correctly and lasts as long as possible.
Would like to know more about Flexible Circuit assembly or pcb assembly services? Email us at sales@pnconline.com

PCB Design for Beginners

PCB Design for Beginners

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Whether you’re just starting in the world of electronics or you’ve been doing it for years, there’s always something new to learn. Design, while it can seem complex at first, really boils down to some simple rules and techniques that will help you to save time and money while making your projects run more smoothly.
There are plenty of steps and processes involved in the PC design process, and as such, there are many things that you need to know in order to create an effective Design. This guide will help you understand how to go about the process of designing your PCBs and take you from beginner to expert.

What Is A Printed Circuit Board (PCB)?

A PCB, is a self-contained module of interconnected electronic components found in devices ranging from common beepers, pagers, and radios to sophisticated radar and computer systems. The circuits are formed by a thin layer of conducting material deposited, or printed, on the surface of an insulating board known as the substrate.
Layers of insulation called traces carry electrical currents between various points on the board. Capacitors, resistors, inductors, semiconductors such as transistors and diodes, and connectors may also be attached to this surface through holes that have been punched into it with a special machine called a drill press. All parts on the board must have features small enough so that they can fit inside this drilled hole with no problems at all.
One major aspect of a design is to make sure there is plenty of room around each component to minimize noise caused by electromagnetic interference. In addition, great care should be taken not to put two closely spaced components on top of one another because this could lead to one component interfering with the other’s signal voltage.

What Are The Parts Of A PCB?

A PCB is made up of a few different parts, such as the board, the surface finish, the solder mask, and the silkscreen. The board is the green part that everything is attached to.
The surface finish is the layer that helps protect the copper from corrosion. The solder mask is the green coating that helps prevent short circuits.

The silkscreen is the white print on the board that has the logo and part numbers. There are many more parts that go into a PC Board but these are the basics.

The materials used in building a PCB will vary depending on how they will be used. There are four main types of boards, including paper-backed FR4, epoxy-coated FR4, Kapton, and ceramic substrates.

Paper-backed boards are usually cheaper because they don’t require special equipment to make them whereas other boards may need expensive machinery or specialized chemicals during production.

Epoxy-coated boards can be damaged by water and UV light while Kapton doesn’t corrode as FR4 boards do. Ceramic boards can also get damaged easily.

Paper-backed FR4 is often used in low-volume production environments with surface mount technology (SMT) devices such as resistors, capacitors, diodes, integrated circuits, and inductors.

How Do I Begin?

Maybe you’ve designed a few simple circuits by hand and are ready to take the next step. Or maybe you’ve never designed a circuit before but have some experience with computer-aided design (CAD) software. Either way, this guide will teach you the basics of PCB design.
The first thing you’ll need is an electronic CAD program. The most popular programs are Eagle, KiCad, and Altium Designer. They each offer trial versions that let you get started without investing any money upfront. You can download them from their websites or find them on your operating system’s app store.

Choosing the Right Software

When it comes to PCB design software, there are a few different programs you can choose from. But which one is the best for you? It depends on your needs and what you’re looking for in a program. If you’re just starting, we recommend trying out a few different programs to see which one you’re most comfortable with.

Once you have a better idea of what you need, then you can start narrowing down your options. A good example of this would be if you needed to design circuits with specific electrical requirements or desired material properties. You should also see if you work with a team of people on projects and want them all using the same system. The biggest thing when choosing a PCB design software is making sure that it meets your needs as well as your budget.

If you want to learn how to design your PCBs, you’ll need to know how to use a CAD program. These design programs are used by designers to create electronic schematics and layout boards. The schematic consists of all the components needed in order to power the circuit while the layout shows where each component should be placed on the board. Two popular CAD platforms include EagleCAD and KiCad. Both are open source but have different strengths.

EagleCAD is known for its intuitive interface while KiCad has better compatibility with older hardware. One important thing to note is that every time you make changes to the schematic or layout, they need to be re-synced with one another. If they aren’t then small mistakes can easily turn into large ones later on. To avoid this problem, check the sync settings at the top of the screen before making any modifications.

PCB Design for Beginners
PCB Design for Beginners

Learning About Board Etching And Printing

Before you can start creating your PCBs, it’s important to understand the basics of board etching and printing. Board etching is the process of creating electrical circuits on a substrate, usually using a photochemical process. This is typically done by first creating a master template, which is then used to create a negative film. The negative film is then used to create a resist-coated board, which is exposed to UV light and developed. The exposed areas are then etched away, leaving behind the desired circuit pattern.
In contrast, PCB printing is often performed in what’s called surface mount technology, SMT. In this type of manufacturing, components are placed onto a flat surface, like sometimes copper coated with solder paste applied between them to connect them.
A final coating may be applied before the SMT assembly undergoes reflow soldering. Once finished, the boards can be separated from one another and packaged. There are many different types of PCBs including single-sided boards, double-sided boards, flex boards, and rigid-flex boards that may also be utilized.
Choosing the right kind of board depends largely on how they will be used as well as cost factors such as materials and labor requirements. For example, flex boards are less expensive than rigid-flex boards because they use flexible plastics rather than stiffer fiberglass or FR4 substrates.
However, the tradeoff is that these boards cannot be mounted to something. Single-sided boards are also cheaper but may not offer the same level of protection against EMI interference as other types of PCBs might be able to provide.
Double-sided boards, on the other hand, offer more protection against interference but require more work when designing them due to routing limitations. They also take up more space than single-sided boards, meaning fewer components can fit on each board.
When deciding on the appropriate PCB type for your project, it’s important to weigh all of these considerations carefully so that you make an informed decision about what is best for your needs.

Tips for Successful Board Prototyping

1. Use quality materials- This is important because you want your prototype to look and feel like the final product. Plus, it will help ensure that your board functions correctly.

2. Make sure your design is clear and concise- A well-designed board will be easier to troubleshoot and will save you time and money in the long run.

3. Pay attention to details – This includes things like trace widths, spacing, and clearance. The smallest of details can have a big impact on the success of your PCB.

4. Create a schematic – If you’re not experienced with schematics, there are plenty of resources online to help guide you through it. Remember that your schematic should match up with what’s on the PCB and vice versa! For example, if you plan to use LEDs on your board then make sure they’re included in the schematic.

You’ll also need to decide which type of LED, transparent or non-transparent you want so you can include that information as well. Keep these four tips in mind when designing your next PCB and get ready for a successful prototyping experience.

5. Build a prototype from scratch – We know that building your first PCB from scratch can be intimidating, but there are quite a few options out there for those interested in learning how to build their boards. So far, this guide would be enough for those who are new to PCBs.
Would like to know more about Design or printed circuit board assembly? Email us at sales@pnconline.com

Four Stages of PCB Design and Assembling

Four Stages of PCB Design and Assembling

PC Board, pcb assembly, pcb assembly services, Printed Circuit Board, SMT assembly, , , ,

PCB is a printed circuit board that helps connect different electrical components. The board is a combination of laminated material, and the copper foil laid on a non-conductive substrate.
A PCB is the main part of any electronic device, so it has to be perfect. It should have functional components and microelectronics circuits to perform well. Development of PCB goes through different processes that you should know well. PCB manufacturing has 4 stages, including design, manufacturing, PCB assembly, and PCB testing.

First Stage- Design

PCB design involves different steps, such as schematic design, layout planning, the placement of the components, routing, and manufacturing files.
PCB schematic design: It is a blueprint of PC design that shows all PCB components with symbols. The schematic design is always according to the technical requirements of the user.
Layout planning: After the schematic design, you have to develop the layout of a PCB that includes physical components’ models,the shape of the PCB, and the structure of a PCB.
Placement of components: It involves planning the placement of various components. You decide on the PCB layers according to your requirements. The right placement of the components ensures a flawless board, decreasing the production cost.
First of all, the designer places the fixed components in the layout, including switches and connectors.
Then, the critical components are placed, such as memory chips, microprocessors, as well as power supplies.
Then the supporting components of the PCB are placed, like inductors, capacitors, and resistors.
In the end, the decoupling capacitors and terminating resistors are placed.
Routing: Once the components are placed, you have to connect all components through trace routing. There are four ways to do so, such as manual routing, auto-interactive routing, semi-automatic, and batch-auto routing. You can choose any method according to your Printed Circuit Board and budget.
Design: In this stage, you have to plan for the number of board layers, dimension of the board, and types of components. You can use a special app in this case, such as EDA or electronic design automation. The designer often adopts the SMT instead of a through-hole technology, depending on your requirements.Once the design is over, you can export the design files to CAD or Gerber format.
Preparation of manufacturing files: This is the last stage of design where the designer exports the Gerber files for manufacturing. The manufacturer needs these files to develop a printed circuit board.

Four Stages of PCB Design and Assembling
Four Stages of PCB Design and Assembling

Stage 2-Manufacturing of Circuit Board

Once the manufacturer receives all design drawings, he starts making PCB. It involves different stages as described below:
Design Imaging:The manufacturer uses a plotter to convert the PCB design files into filmslike they resemble the photo negatives of the schematic design. The printer uses black and clear inks for inner and outer layers. Copper traces and circuits are shown with black ink, whereas the non-conductive parts are shown with clearink.
Printing of Inner Layers On Copper: It is the initial stage of PCB manufacturing. The engineer uses a substrate material to make a laminated board. Like, epoxy resin or fiberglass are common in this case. The design of the PCB is printed on the board, and then he pre-bondscopper on a board’s both sides. After that comes the etching of copper, and then the board is protected through a photo-sensitive film.
UltravioletLight: the manufacturer then exposes the resist-covered PCB to UV light to strengthen the photo-reactive material. Then the board is cleaned with an alkaline solution to get rid of unnecessary copper particles. The expert checks the board to remove any errors and then goes to the next stage. The main aim of UV blasting is to develop a PCB Board according to the schematic drawing.
Inner layer’s etching: copper’s inner layer needs chemical etching for removal. The process of photoresist prevents the essential copper from etching. The board size determines the amount of the solution and etching time which is less for small boards but more for large boards.
Some other manufacturing processes include:

  • Alignment of layers
  • Optical testing
  • Layer pressing and lamination
  • Drilling
  • Plating of PCB
  • Imaging of external layer
  • Etching of external layer
  • Solder mask
  • Silk screening
  • PCB finishing
  • Testing
  • Profiling
  • Quality testing
  • Packaging of PCB
  • Shipping of PCB

Stage 3-PCB Assembly

The assembly of a PCB involves four stages, such as soldering, placement of components, solder pasting, and testing. Let’s review them in detail.
Solder Pasting: It is like t-shirt screening, as it involves solder paste stenciling. The stencil is made of stainless steel and it’s very thin. You have to use the stencil to apply the paste in areas where different components will be installed. In this process, flux is used for melting the paste to help it bond to the PCB.
Placementofthe Components: Once you are done with the solder paste, you need a pick and place the tool for the components. Generally, it is SMT or surface mount technology where components are placed on the PCB surface. Initially, it used to be a manual process and assemblers used tweezers to pick and place different components on the board. However, new technology has made this process automated due to robotics and it’s more precise and consistent.
Soldering of PCB: After the placement of components, you have to place the PCB on a conveyor belt to help a board move to a reflow oven that heats the board. The heating helps melt the solder paste, and bond the components on the board permanently. However, if the board has more components other than SMDs, it would need a through-hole insertion that involves more advanced soldering.
Testing of PCB Quality: Sometimes, the components are misplaced during reflow when the PCB is moving. This issue may cause a poor connection, or no connection at all, or the parts are not well-connected. So, you need to inspect the PCB to ensure a flawless function. A PCB can fail this test even if it passed other tests, and a failed PCB goes to scrap or you have to recycle it with all essential processes until you get a flawless circuit board.

Stage4-PCB Testing

Manufacturers use different methods for PCB testing to ensure that it will function correctly. These methods include in-circuit, optical inspection, flying probe, turn-in, x-ray, anda functional test.
In-Circuit: It is also known as ICT, or you can call it the bed-of-nails inspection. In this method, PCB is pressed on the bed of probes. It is highly accurate because it checks all components of a PCB. You can also test the BGAs with this method. Moreover, it also tests the solder integrity of the bottom-terminated components.
However, this test is expensive and time-consuming. Moreover, it does not test the non-electrical parts and connectors.
AOI, Automated Optical Inspection: This testing method involves a visual inspection of the board. It is done with the help of HD cameras, LED lights, UV, and high-level infrared. The test is contact-free and helps check poor solder joints or missing parts. It also tests the smt assembly issues and it’s very accurate.
However, it only inspects the preprogrammed errors and can’t check defects regarding glue or sealing.
Flying Probe Test: It involves probes that help test the upper and lower surface of a PCB. This PCB testing method is cost-effective, consumes less time, is easy to do, and is compatible with many applications of PCB assembly. However, it is slower than other testing methods and not ideal for complex testing.
Burn-In Test: In this test, PCB is exposed to a high temperature to see if it works well. It ensures a lifetime product and enhances the brand because of an effective end product.
However, this test is costly and can affect a PCB by damaging its components. Moreover, it can be less reliable due to voltage scaling.
Inspecting Through X-Ray: It involves an x-ray machine that inspects a PCB. It thoroughly checks soldering which is hard to detect with AOI. The x-ray inspection is ideal for thick or multilayered PCBs. It also detects the voids or bubbles and can also check the components under a shield.
However, it needs expensive x-ray machinesand can cause hazards in the workplace.
Functional Test of PCB: It involves functional testers that you connect to the edge connector. It creates an electronic environment for which a PCB is made. It inspects the functional errors and identifies the analog issues. It also checks issues with digital circuitry.
However, it is very costly and needs high-end tools, which are too expensive. It needs a proper understanding of the working atmosphere of the DUT.

Final Thoughts

The development of a PCB involves different processes, including design, printing, assembling, and testing. Each stage is further divided into different parts, and you have to understand all stages to create a flawless PCB.
The board is a combination of laminated material, and the copper foil laid on a non-conductive substrate. A PCB is the main part of any electronic device, so it has to be perfect.
Would like to know more about the design or pcb assembly services stages? Email us at sales@pnconline.com

Design Elements Influencing SMT Assembly

Design Elements Influencing SMT Assembly

Circuit board fabrication, PC Board, PC Board fabrication, PCB Design, PCB Fabrication, 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