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Printed Circuit Board Designing Issues

Printed Circuit Board Designing Issues

 

Printed Circuit Board
Printed Circuit Board

PCB’s play the role of heart and soul for any electronic device. This is the skeleton of any electronic device that applies to almost every field’s tools. Such as telecommunications, big to small computers, hardware, and military equipment. In a nutshell, you can say that an electronic device is completely dependent on its skeleton structure (in other words, on a printed circuit board) in order to perform well. As the PC board is the way to connect the within components as well as it maintains a healthy communication with the outside world so the electronic device can perform its functions, a simple or a slight mistake can lead to complete failure of the circuit or device and malfunction also.

It’s not an easy task to manage the designing of the circuit board, its internal associations, components, and layers. The chances of catastrophe and failure of the circuit are high when the layout design of the circuit is bad. Although the modern tools are assuring the innovative designs as compared to past designs. These tools also ensure the better design at the proper cost because in some cases, bad designing of the printed circuit board can lead to an expensive manufacturing process of the board. With that being said it is obvious that errors are more likely if the circuit designing is not done properly or in a timely. That’s the reason designing should be done on time before the manufacturing process. Reviewing the designing process before prototyping is also crucial.

Once the designs are reviewed independently then the prototyping process should come forward. This will reduce the overall cost of the manufacturing process as well as the failure of the circuit. We will discuss the common errors and design issues that occur during the process and lead to system failure. Moreover, in this article, we will discuss a few things that need to be kept in mind while designing a PCB for any circuit board manufacturer.
Some of the most common issues that happen during the manufacturing and designing process are discussed below.

The improper layout of circuit board:

As we know that devices are becoming smaller and smaller. This smaller requirement forces the combination of complex and thin development of the devices. Designers are also forced to make the design using smaller components and minimizing the distance between these components. Similarly, it is appreciated that minimal footprints are being used in the designing process. The smaller components used in designing reduce the footprints in the layout. For this purpose, a designer usually selects a layout in which components are placed very close. But this may result in an inefficient layout which further causes non-compliance and connection issues. The connection may go wrong in an incomplete layout. To get the desired functionality it is important that the defined layout of the circuit suits its needs also.

Moreover, the other thing that needs to be considered is that there should be enough space in the circuit to add some additional components or any other alternatives. If there is no need to add additional components, then these can always be removed before the manufacturing process takes place. So, a suitable and maintainable layout is required when you are working on high pin count and small pitch.

The decoupling capacitor is not in the right position:

There is no hard and fast definition that strictly explains the decoupling of capacitors. But for better understanding, we say that decoupling of a capacitor refers to the functionality of a capacitor in an electronic circuit. The decoupling capacitor maintains the stability of voltage in the circuit plane. So, in a designing process, a designer needs to make sure that capacitors are placed in the right position so that the transient or oscillation is providing enough power supply to all the other components of the board. For this purpose, the capacitor should be placed in a parallel position. It is also necessary that the position of the capacitor is as close to the components as possible in your PCB design.

The power source that provides the actual power must be properly routed on a printed circuit board for decoupling of the capacitor and the pin which requires a stable voltage supply. If a circuit is unable to do so, then decoupling of the capacitor cannot work properly. A series of inductors is also added if the circuit has some sensitive components such as analog to digital converter. In this case, the supply noise needs to be removed. This is done by using LC filters.

Antenna layout:

The antenna layout is one of the most critical tasks if your designed product is based on wireless technology. As this is the most critical part of the circuit board design, it is done incorrectly by common electrical engineers.

Also, transceivers transfer the maximum power between the antenna terminals when the impedance is matched perfectly. The impedance means the complexity of the circuit and not the simple resistance. The transceiver and the antenna can only be connected by a proper transmission line.

Mostly it is said that a 50-ohm impedance is enough in the transmission line for maximum power transfer in the antenna. The microstrip (having 50-ohm resistance) is used to attach both the transceiver and the antenna. Some free tools and calculators are there that can determine the printed circuit board transmission line dimension so that a user can achieve maximum and proper impedance. These tools are recommended if the designer is supposed to handle multiple types of transmission lines.

Acid Traps:

Acid trap used for the acute angles in the circuit board. These acute angles can trap acid in the etching process of printed circuit boards. These acute angles can place the acid in a specific corner for more than desired time and this results in eating more acid than intended. The circuit can become more defective and can cause a severe issue and the connection can be compromised.

This acid can also remove copper from the blackboard. Acid traps are commonly occurring problems are most designers are aware of them. That’s the reason. Designers are trained to avoid them also. But mistakes are always there to happen. Most of the time, acid trap errors happen because of human errors. And some software designs are also used to set the circuit if the setting is not done properly.

Acid traps can easily be caught in the second review of work, but oversight is possible. Moreover, the recent circuit tends to have less acid trap ratio than the previous ones because fabrication is switched by photo activated etching solution during the PC Board fabrication process.

Starved Thermal:

In the printed circuit board, the plane is connected to the pad by thermals. These pads are surrounded by thermals in the circuit. Thermals are an important component in the soldering process and are helpful for the pads in dispersing more heat effectively. But sometimes an error can happen because of an incomplete connection between thermal pads or the rest of the plane. This reduces the effective heat release or transfer by the system. And as a result, the circuit can catch various function problems. Starved thermal is a problem that does not allow the transfer of heat from the pad to the entire plane. This is more problematic if the circuit is under heat and in the soldering process. The assembly process will be slowed down and the pad will take more time to reflow and in heat transfer. In the end, the circuits having starved thermal can go through heat prone, insufficient heat transfer, and heat damages.

Starved thermal happens because of the defect present in the manufacturing process. These thermals are connected correctly in the computer-aided design system, but they have a weak connection with the entire plane board. This results in over machining and improper modeling in the circuit. The problem can be solved by replacing the thermal, but this is time-consuming and cost-consuming. But these thermals can be spotted before they make severe damage to the circuit.

Silvers:

Some narrow wages of copper and silver are used in printed circuit board manufacturing and can cause some serious problems during PCB manufacturing. These silvers occur in one or two ways and are produced in the etching process. The first way to produce silver is by etching the long thin feature of copper and solder mask.

On the other hand, silver can also be produced when a section of the printed circuit board is cut down too low or too deeply. The only way to reduce silver is to avoid the chance of producing them. The section width should be minimum. The producer can check the silvering defect by DFM.

These were just a few issues that commonly happen during printed circuit board designing and can be checked by the manufacturing committee. But sometimes, these issues have been overlooked that cause the problem in the end. The functionality of the circuit board fails, and the company and the user have to pay the cost for it. The only way to avoid these issues is by understanding the design properly.

Get your PCB design sorted with PNC. PNC is providing a turnkey solution to sort all your PCB design issues under one roof. Just contact us now at sales@pnconline.com.

Laminate Material for PCB Board Fabrication

Laminate Materials for PC Board Fabrication

Printed circuit boards are now a common part of our daily routine. We are using PC Board Fabrication in almost every electronic device we are using for our work and entertainment purposes. Whether it is a mobile phone, or a screen, or a remote for television, every device consists of a printed circuit board. That’s the reason understanding its working is kind of crucial these days.

When we discuss printed circuit boards, we need to understand their layers. PCBs have various layers, and these layers are concerned with their working. These layers will vary according to their working. For example, most multilayer PCBs are used when the device is complex, and we need multiple functionalities. Now let us understand how we do lamination in printed circuit boards and how it is related to layers of PCBs.

What is Lamination in Printed Circuit Boards?

As we have discussed before, there are many types of printed circuit boards. They are both single-layer and multiple layers depending upon the functionality of the device. So, for multiple layers of printed circuit boards, lamination is required.
We can say that lamination is a process in which successive layers of materials are built and then binding those layers to strengthen those layers to protect different substances.
One of the important steps in building a printed circuit board is lamination. Circuit board manufacturers do the lamination process to make sure that copper is not conducting a current or signal inadvertently. There is a substrate in the printed circuit board that plays the role of canvas on which all the components of printed circuit board assembly are attached. Copper is laminated to that substrate. Lamination is an integral part of printed circuit board manufacturing. The lamination process will vary according to the requirement of the circuit board. The type of lamination you choose for your circuit board will decide its reliability and performance for the particular device.
Now we have understood what lamination is. Let’s understand the role of fabrication and then we will see how both these terms are related and how the lamination process takes place.

What is Printed Circuit board Fabrication?

Different layers of the circuit board are placed together on a particular surface pattern to be used in printed circuit board manufacturing. Fabrication is the method of assembly for circuit boards that are used in different electronic devices such as computers and phones. fabricated PCBs are used for customer special products. Sometimes the manufacturers fabricate the circuit board in the house or sometimes they hire a third party to do so.
It is being said that fabrication is the skeleton of any circuit board. Why is that? Fabrication is the process in which we give or transform the sketch of the circuit board into a structural existence. The specifications are provided for the circuit board and fabrication is a way to transform the sketch into the physical design. There are few techniques that are used for this purpose. We will explain those techniques later.
Lamination is the backbone of circuit board fabrication. For better understanding, let’s discuss the types of laminations.

Types of laminations:

If you are not aware of the types of printed circuit boards then you are more likely to face difficulties in designing the circuit board. Types of laminations in circuit boards will help you analyze the designing and the development stages your circuit will go through. Hence the type of lamination will decide the overall reliability, stability, and performance of the printed circuit board. There are four layers of a simple printed circuit board that are compulsory for basic performance. These layers are:
• Substrate
• Solder mask
• Copper
• Silkscreen
And then comes the lamination which is used to hold these layers together. The lamination is done under pressure and temperature. Thermoset resins are used in this process to create a uniform thickness that is required for the process. Typical numbers and letters are used to show the type of lamination which basically shows the characteristics of the product used in lamination. These characteristics are dielectric constant, the tensile strength of the product, shear strength of the material, loss factor, glass transition temperature, fire retardant, and the rate of change of thickness with temperature. For example, if you see FR-4 then it is sure that FR-4 is the most used product in the lamination process. There are different types of lamination that are done in printed circuit boards. The explanation is given below:

1. High TG epoxy:
High TG epoxy is used for multilayer printed circuit boards, and it is most suitable for them. as we already know that multilayer PCBs are used in complex devices from which we need higher functionality. For better epoxy rate in those PCBs, high TG epoxy lamination is used. There are certain characteristics of high TG epoxy. Such as high chemical resistance and increasing heat. TG epoxy is used when we are concerned with tolerating high heat. The temperature in this lamination is similar to the melting point. These characteristics will increase the rigidity of the circuit board and the performance. This Tg is best for ROHS PCB assembly.

2. FR-4:
You have probably heard FR-4 in the world of lamination before because it is the most widely and commonly used material for lamination. The reason for its popularity is its characteristics of a good trench to weight ratio. This material is flame-resistant which makes it more reliable. The mechanical, electrical, and physical properties of the material stay maintained when there is an increase in temperature because of flame-resistant properties.

3. High-performance FR-4:
As clear from the name, high-performance FR-4 is used when we are supposed to make a multilayer and multiform complexed purpose printed circuit board. TG is the temperature variation that is higher in high-performance FR-4. This increase results in high stability and maintainability. Also increase in TG performs better in high-frequency circuits because of low dielectric powers.

4. Polyimides:
Polyimides are also used in multilayered printed circuit boards. Polyimides are used in lamination where we need extreme environmental stability. Rigid, flexible, and high-density circuit boards require polyimides in the lamination process. Mechanical, thermal, and chemical properties of the material can be increased by using polyimides. Due to these properties, polyimides are highly recommended for heavy applications such as military, aerospace, consumer electronics, and automotive.

5. BT Epoxy:
If you need high standard thermal, electrical, and mechanical properties in printed circuit boards then BT Epoxy is the best available choice among all. This laminate is designed to use in multilayer PCBs, and it helps in bond strength at high temperatures. BT epoxy is recommended and suitable for lead-free printed circuit boards.

6. Teflon:
There are particular issues with using Teflon in a printed circuit board that results in conventional board shops. But despite this fact, Teflon is highly recommended and suitable for high-frequency applications. Teflon is available in many different types. The most used type is woven Teflon with glass. This material is very flexible and makes SMT assembly a little more difficult.

7. Copper Clad:
Glass fiber and wood pulp paper are used in copper-clad laminators as a reinforcing material. High voltage circuits require copper-clad laminates. These circuits are mostly based on some kind of specific size, appearance, specification, chemical, environmental and physical performance.

We have understood the types of lamination. As we know that fabrication is done by the process of lamination. To better understand the process of lamination, we need to understand the techniques. There are certain techniques to perform lamination for fabrication in printed circuits boards. There is a stage in fabrication in which inner layers and foil are heated and pressed into the circuit board. Lamination is required for this stage. Different methods and materials will be used in circuit board fabrication depending on the requirement of the printed circuit board.

Teflon Microwave:

Teflon microwaves laminates are used in circuit boards where high-speed signal flow is required such as RF., they are ideal PCBAs for radio frequency applications because of their high properties of minimal electric loss, reliable dielectric constant, and tight depth tolerance.

Multilayer PCBA:

In this method of lamination, multilayer PCBA is fabricated in several layers. Thin etched boards and trace layers are used in this lamination that is then bonded. Internal layers are placed under high temperature and pressure and are heated intensely. The Circuit board is then laminated with dry photosensitive resistance as the printed board cools down slowly and pressure also releases gradually.

Sequential Lamination:

The most modern technique for PCB fabrication is sequential lamination. This technique is widely used for PCBs having two subsets. An insulating material is placed between the layers of PCB in order to create a subset of PCB. Then the standard lamination process of circuit boards is implemented. This method requires more time and cost for the process. But this is the fundamental technology that is being used for the fabrication process in multilayer PCBs.

High density interconnects (HDI) printed circuit boards are not possible to develop without sequential lamination. HDI is now the most advanced place for electronics so sequentially implementing lamination can ensure the benefit of manufacturers.

PNCONLINE is the market leader as a circuit board manufacturer and will assist in the overall assembling process.

Interested to know more about PCB laminate materials? Just write us now at sales@pnconline.com.