Everything You Need to Know About Circuit Board Assembly!

mwcms on September 13, 2021

Most of the electrical appliances that run our lives on a daily basis include about 300 feet of tiny wires inside. This wire is the main component that adds connectivity inside an electrical product. It allows all the other small components in an electrical appliance to work seamlessly together.

The more complex an electrical appliance is, the larger the number of components and the wire inside it. However, you may be wondering where this wire is located. Well, this is where the printed circuit board assembly comes into play.

What is a PCB?

The printed circuit board or PCB is the small circuit board inside most electrical appliances. They are either green or blue and at first glance, they look like ordinary pieces of scrap plastic. But in reality, they are actually a multi-layered board that consists of an abundance of copper wires.

This scrap of flat metal is the surface on which manufacturers will precisely and carefully place all the essential components using expensive heavy machinery. Along with that, small copper wires will connect between the components and provide the necessary connectivity that occurs between all the components. This connectivity allows the components to work together and as a result, this paves the way for an electrical appliance to function.

What is inside?

The printed circuit board consists of ten conductive layers. The top and bottom layers of the Circuit board assembly make for surfaces on which manufacturers will mount components and they also act as multiple antennae. Moreover, each of these components on the circuit board requires plenty of power and ground and the PCB has entire layers that are only responsible for providing power and ground.

They are also aptly named power planes and ground planes due to their specialized role. Other ground planes that make the circuit board assembly serve the purpose of electromagnetic shielding and heat dissipation. The remaining four middle layers carry all the communication traces, which means that they carry all the signal wires.

Each of the conductive layers is copper, and between these conductive layers, there is insulating fiberglass, along with an epoxy resin that protects against the flow of electricity between the layers. A common PCB has a total of ten conductive layers, however, in a more technical and complex application, the layers can range up to 50 or more layers.

On the other hand, you may also find a PCB board that is simpler, with only two layers. Not to mention, on the top and bottom layers of a PCB, you will find a coat of solder mask, which offers a surface on which manufacturers will place components using high-tech machines. On top of the soldering mask is the silkscreen, which is nothing but the ink that indicates the placements for components by marking the circuit board.

The Assembly Process

After all the components of the PCB are manufactured, they need to be assembled before the PCB can go into the production line. This assembly process will involve the application of solder masks, automated component placement, along with the electrical testing of the bare board.

Final Thoughts

Printed circuit boards are more widely used inside computing devices, and since each model of smart phones and laptops along with other devices are different, the shapes and designs of circuit board assembly also differ vastly. Overall, it is fair to say that they are integral components of the modern technical era, and without them, none of the highest technical appliances can function.

 

 

How does Automated Trace Routing Work in PCB Design

mwcms on July 29, 2021

Every electronic device that you use consists of over a hundred meters of wires, along with dozens of small copper components. These components work seamlessly together to run a specific electronic device, whether it is a Smartphone, television, or remote control. 

All of the wires and components perfectly attach to a thin-layered board, or PCB (Printed circuit board). When engineers mount all the components on this surface, it provides an organized framework for all the small structures to communicate with each other. 

PCB DESIGNING 

PCBs consist of conductive material that sits on insulating material, or the substrate. When you categorize PCBs based on this, you get two classifications, the single-layer PCB, and the double-layer PCB. The single-layer PCB includes a one-sided conductive coating, while the double layer has a coating on both sides. 

One of the many ways to decrease the build-up of heat in a PCB design is to widening the traces on the board. This is one of the routing rules out of many that creators follow when designing PCBs. The wider the distance between the traces, the lesser will be the resistance of the flowing current. To calculate trace widths, you can seek the help of online trace width calculators. 

Similarly, you can find methods that encompass the manual routing process. In an electronic design, automated trace routing is the way to go amidst modern technological advances.

WHAT IS AUTOMATED TRACE ROUTING?

This is a method of design for the printed circuit board, along with the integrated circuits, or (ICs). This step automates the process of placement when integrating a PCB. The dynamics of this method predicates upon identifying the placement for each active component of a PCB. 

The automated trace routing method allows you to enable an automatic routing system that systematically makes all the placements themselves. You can find auto-routing software such as Altium, which provides users an interface that helps access automated trace routing. 

With the help of automated trace routers, encoders can increase their productivity and not waste their time in manual routing solutions. 

SHOULD YOU USE AN AUTOMATED TRACE ROUTER? 

Auto-routing tools can be of immense help, especially if you are a beginner designer. They have incredible use and benefits for simpler designs. However, skilled and experienced designers that incorporate complex routing placements do not use automated routers. 

This is because the automated routing tools will often not have the complex routing strategy or layout in their systems. Therefore, whether you should use an automated trace routing tool depends entirely on the layout of your PCB, the complexity of your strategy, and the settings that you are particularly looking for.

AUTOMATED TRACE ROUTING ALGORITHMS 

Algorithms ultimately define the function of an automated trace router. They are the fundamental construct of the different routing topologies. In other words, they are a set of instructions that automate the routing process, speeding it up, and making this lengthy task easier. 

The three main algorithms for auto-routing involve random search, directed search, and river routing. Each of these algorithms has its advantages and setbacks and suits each encoder for a different set of tasks. 

TO CONCLUDE

If you are new to PCB design, then auto-routing tools can be emphatic to get you started on your PCB projects. In hindsight, the benefits of an automated trace router outweigh some of the drawbacks, especially if you consider the recent advances in their technology.

PCB Finishes: Immersion Silver

mwcms on December 7, 2020

It is a well-known fact that printed circuit boards (PCBs) use copper surface finishes as a common practice. If left unattended and unprotected, copper will deteriorate and oxidize, leaving your circuit board unusable. 

A surface finish plays a vital role in creating an interface between a PCB and its components. Here are two of the main functions of a surface finish.

  • It helps protect the copper-based circuitry
  • It provides you surface that can facilitate soldering during the assembling process of soldering components to your PCB

What Is Immersion Silver?

Immersion silver surface finish is a type that you can apply directly over your printed circuit boards’ copper surface. This surface finish is most commonly used and ideal for metallic dome contacts, aluminum wire bonding, and EMI shielding. 

The thickness of this material is between 5 micro-inches and 12 micro-inches, respectively. Additionally, immersion silver has lasting capabilities for at least a year. 

Immersion silver surface finish does not react to copper the way Tin does. However, if you expose it to the air, it will tarnish; therefore, you must store the circuit boards with immersion silver finish in an anti-tarnishing packaging. 

If you do everything right and store it in proper packaging, the PCB will still be solderable for 6 to 12 months. However, once you have removed your printed circuit board from the packaging, you must make sure that it goes through soldering re-flow within the next 24 hours.

In case you wish to achieve a higher shelf life than gold, plating is the most viable solution. 

Benefits of Immersion Silver Surface Finish

PCBs always come with coated surface finishes. Adding a decent finish enables and ensures decent soldering capability, as well as it protects the copper circuitry of your circuit board from the outside air. There are several types of immersion finishes, such immersion tin, immersion gold, etc.; however, immersion silver is gaining popularity due to certain features it offers. 

It is attracting a lot of attention from the PCB manufacturers. Here are some of the key advantages that declare it to be the preferred material for surface finishing in the circuit board industry. 

  • It allows the proper spreading of solder on its surface, allowing better soldering of circuit board components. 
  • Immersion is one of the RoHS compliant PCB surface finishes, and it is also environmentally friendly. 
  • Compared to OSP “Organic Solderability Preservative” surface finish, the surface with immersion silver finish will demonstrate better resistance to several environmental aging factors. 
  • The immersion silver is a material surface finish that comes with the capabilities to survive multiple re-flows. 
  • Immersion silver has better and enhanced electrical properties. 
  • It produces a flat surface and facilitates strengthened solder joints than HASL surface finish. 
  • Immersion silver is immune to a phenomenon known as a black-pad interfacial fracture. 

All of the advantages mentioned above make immersion silver surface finish an ideal choice for PCB manufacturers. 

Choose Wisely

You must select an adequate surface finish for your PCBs. You can do so by considering several options while you factor material costs and performance requirements. 

For instance, you are looking for an option that is lower in cost than Tin-Lead. HASL may sound like a more obvious choice, but it is not the most suitable option, especially when it comes to RoHS compliant products. 

In case you are unsure of what type of surface finish you may need. You can always get help from third-party PCB fabrication services prior to making decisions you may regret later. A little bit of research will result in cost-effective and high-yielding design.  We are here to answer any questions you may have and help you make the best decision for you. Contact us today!

How to Panelize your Boards for Assembly

mwcms on September 21, 2020

So you have managed to sketch the perfect printed circuit board (PCB) assembly design. You cautiously created a layout of your components and respective traces for optimal thermal and EMC/EMI considerations. You even ensured that your PCB fits perfectly and conveniently within the secure socket of your product. 

However, there is just one issue. You contact your regular fabrication house only to find out, the transfer conveyors they have on their production machinery cannot process single boards. They inform you that your conveyor width has to be 2 inches or more. 

Eager to get your order, chances are their sales liaison will recommend you to make your design bigger or try PCB panelization. 

However, the designed enclosure on your product does not have ample margin for expansion of the width of your PCB. Even if it could, the price to do so for a single board will be too steep. PCB panelization is an ideal solution for such situations. 

Let us find out what PCB panelization is and how it can be helpful for your manufacturing needs. 

What is PCB Panelization?

It is a technique used in the manufacturing process. This process enables smaller manufactured boards connected en-masse as a single array. The whole exercise makes it easier to transition through the assembly line. 

There is another term used for PCB panelization known as “Array.” In other words, it is a process of combining your single printed circuit board multiple times to create a larger array of boards connected together. It is also known as “stepping out.” 

The whole process of PCB panelization is reversible; hence you can easily remove or de-panelize boards individually from the array for installation or packing into a product. Alternatively, you can also use panelization to create an edge around an individual board to increase the width that fits the assembly line. 

Factors to Consider

If you wish to reap the benefits of panelization in a mass production environment, it is essential to embed the following design considerations in your PCB assembly. 

PCB-Array Strength

There is a tradeoff when it comes to the array’s integrity and ease of de-panelization during the product. Increasing your per array board count can also increase the strength while reducing the vibration. 

Component Layout

Placement of all the connectors and components, especially the ones hanging off the board’s edge, can limit panelization options. Be thoughtful of where you locate the sensitive SMT components on the edges.

PCB Shape

The board’s shape can cause complications in the panelization process. Rectangles are ideal; however, if your board’s shape is complex, using a CAD program can help you fit an unusually shaped PCB into the desired array. 

Tooling Holes

Breakaway process edges and arrays can provide you spaces for tooling holes. It will help you run automated testing on your PCB assembly line. 

How to Panelize Your PCBs for Assembly

There are two ways to panelize your PCB for assembly.

V-Groove

Using V-groove panelization, you use a triangular saw to cut approximately one-third into each side of your PCB panel. It leaves you with a thin sector for FR4 that holds PCBs together, so you can separate them using a simple tool.

You can only use this panelization process on designs with straight lines separating all the PCBs. But you cannot use the v-groove technique if PCB components are hanging over the edges of any of the boards. Using V-groove panelization would damage your board. 

However, V-groove is a faster route to panelize your boards, plus it adds little space to the overall size of your panel, reducing the costs. 

Tab-Route Panelization

For boards that are inseparable by straight, simple lines or if a PCB design involves multiple boards with various designs, tab-route panelization is the solution. It is a far more flexible strategy for board panelization. 

In this process, you use a router for cutting through FR4 between PCBs. It leaves small tabs to hold all the boards together when going through the assembly. You can break these tabs apart by hand or using de-panelization tools 

Tab-route allows your boards to have components overhanging from the edges. Typically, a tab-routed PCB has a series of holes, making the separation of the boards easier.

At Nova Engineering, we are ready to help you with any PCB orders or issues you may have. Contact us today!