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PC Board Electrical Schematic and Its Functionality?

Whatever we create, including a PC Board,is a picture or an idea that we convert to paper in the form of a diagram. You can’t proceed with manufacturing without a proper PCB layout or schematic.

An electrical schematic is a conceptual plan or drawing that helps understand the physical aspect of a PCB in terms of assembly.
The basic purpose of electrical schematicsis to have design communication.It should help manufacturers clearly understand it.Besides, the schematic directs you to makea PCB layout.

Schematics involve specific elements which are essential to understand, such as:

  • REFDES or reference designates
  • Symbols representing the components
  • Outputs
  • Nets

To know schematics in detail, you have to understand the above elements.

REFDES or Reference Designators-Identifying Labels

Identifying labels or reference designators help understand components because they describeso much about them. If REFDS is precise, it helps a reader to identify the types of the components and symbols,depicting every component.
So, each electrical component or part has a standard symbol.However, onlyspecific schematics follow such standards.
In some cases, reference designators can fully describe the component type, like when there is a generic box with pins itrepresents a passive component.

At the same time, reference designators also connect to theBOM, and bill of materials. Every Printed Circuit Board component needs a part number that BOM shows. Besides, it also helps find the area or location where components should be installed.
The format of the reference designators consists of a code in the form of a letter that describes the component, and its type having a specific number.

Symbols Representing Components

The electrical schematic has specific symbols of the physical components of PCB assembly in terms of soldering. They also describe the circuit boards’ structures, such as test points and vias.

The symbols are specific shapes or they are diagrams to indicate the type of PCB components. There are symbols for all electrical components like capacitors, diodes, resistors, and transistors.

The symbol of each component consists of pins that help in creating the electrical connections. The pins of all schematic symbols have specific numbers,depicting the physical components.

Designers can assign either a single symbol or multiple symbols to represent a single component of a PCB. Whereas the components having several pins are assigned many symbols to create a readable electrical schematic.

When a component is having multiple symbols, each symbol representing the same component has a similar designator.

Electrical Components-Resistors

PCB has many electrical components, including resistors. The U.S designers use a zigzag line to describe a resistor. Whereas its symbol is a rectangle according tointernational standards.On the other hand, the letter R in schematics isa representation of the resistor.

CapacitorSymbols and Letter

Capacitors have two types, includingpolarized capacitors and non-polarized, and both have different symbols. The curved line is a symbol of a negative terminal of a polarized capacitor. Whereas the plus sign denotes a positive terminal of a polarized capacitor.Whereas the letter C defines a capacitor in schematics with REFDES.

Inductor Symbol and REFDES Reference

Inductors are also important passive components of a PCB, and their construction involves a series of curves.Manufacturers use a coil of wire to make inductors. Whereas the letter L defines a capacitor in schematics with REFDES.

Diode Symbol and REFDES Reference

Some other PCB electrical components within the PCB design include diodes that permit the current to travel in just one direction. The diode has different types, including

  • Zener diodes
  • LEDs or light-emitting diodes
  • Schottky diodes

Zener diodesprevent the reverse flow of a current. However, the reverse flow can happen at a certain electrical power level.
There are also LEDs or light-emitting diodes which emit light when having a forward flow of a current.
The Schottky diode has simple features,but it switches quickly and the voltage drops in a lower forward direction.
Other than LED, the letter D or L defines a capacitor in schematics with REFDES.

Transistors Symbol and REFDES Reference

Transistors involve the flow of current at the primary terminal and they function like switches. The basic types of transistors include:
Bipolar Junction Transistors-BJTs: It is a current managing device that helps a current flow either into one base pin or out of it, changing to high currents passing through emitters and collectors.

Field-Effect Transistors-FETs: The FE transistor is another current-managing device that helps voltage turn on the current on the pin, via source pins and adrain. Various drawings indicate transistors and the letter Q and M define a resistor in schematics with REFDES and also represent the MOSFET. However, some designers use the letter T in the wrong way.
Variable Resistors’ Symbol andREFDES Reference

Variable resistors have two categories:

  • Potentiometers-three terminals
  • rheostats-two terminals

The function of the variable resistors is to customize resistance according to users. An arrow across the resistor represents the rheostats, whereas an arrow on the side of the resistor shows potentiometers.

There are also varistors or voltage-dependent resistors which resemble the variable resistors, but they are denoted by a line across them.The symbols of the resistors include R, VR, and RV, depending on the type of the resistor.

IntegratedCircuits, Symbol, and REFDES Reference

A single-package circuit developed with a semiconductor is an integrated circuit. You can also consider such circuits asamplifiers, processors, power regulators, and memory of a device. The shape of the integrated circuit is like a rectangle or a square that you can install on a PCB. It is a box with power inputs and outputs or pins and sometimes a board has many boxes.

The symbolof the integrated circuit in a schematic is the IC or the U.

Resonator, Crystals, and Oscillators, Symbol and REFDES Reference

PCB also has resonators, crystals, and oscillators, which give a consistent frequency output. These elements are different in terms of circuitry and characteristics but they have a commonfunction.

Some Other Symbols

There are also several other symbols to show interconnections on a schematic having labels to find their electrical nets.
Mostly there is no reference designator for non-component symbols, however, some have symbols like TP or test points, and X, and MH on REFDES.

Understanding Nets in Schematics

The wired connections on the printed circuit boards are what designers call nets. They are lines that connect symbol pins to the nets. You have to properly label the nets while making schematics to help manufacturers identify them. Specific symbols depict thenets to the same or different pages when you don’t draw them as connections, such as interpage and intrapage symbols.

Try not to overlap the nets to have good readability, however, you can’t ensure it every time. A dot or a circle on a schematic diagram shows two nets’ connection. If there is no DOT in a schematic, it means there is no connection between the nets. Whereas advanced drawings have wire hops to show that the nets don’t connect.

Outputs of Schematics-Netlists & BOM

The schematic diagram has two important outputs, including BOM, and netlists. The netlist is a file that designers use to understand routing and parts’ placement on a PCB. The format of thenetlists can vary in symbols. The name of the nets is presented in the netlist, showing thelocation of connectionsbetween the PCB parts. Netlist also has an output tool to give names to the nets which were without names.
Generally, there are several tables in a netlist, listing the PCB components and their names, net names, and some other essentials. Sometimes the netlists include additional information to help you understand the SPICE.

Bill of Materials-BOM

Bill of materials shows data in the form of a spreadsheet,matching the REFDES in schematicshaving a number and a physical component. Designers use different formats for BOM outputs, depending on the nature of schematics and your requirements in terms of output.
There can be many reference designators with independent partnumbers to help with manufacturing. Some detailed BOMs consist of specific part numbers of a company, quantities of components at different locations on a PCB, and the part numbers for different vendors. In other words, BOM has essential information to understand schematics and develop it through different steps, including SMT assembly.

Final Thoughts

You must know that the electrical schematic is a drawing that helps understand the physical aspect of a PCB in terms of assembly. The main aim of electrical schematics is to have design communication and help manufacturers construct the PCB. It should help you clearly understand parts and assembly. All electrical components have standard symbols. But, only specific schematics follow such standards. Different software help make electrical schematics that you can explore online.
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printed circuit board

Differences Between IC and a PC Board

Before discussing the IC, you must know what PCB is. The PC Board or PCB has electronic components to help a device function. All digital and electronic devices have PCBs, like consumer products, smartphones, computers, laptops, tabs, etc. The purpose of the PCB is to eliminate assembly issues and have less wiring, enhancing automation and production.
The PCB has different types in terms of the number of layers. Like, it is either a single layer, double layer, four or six layers, or a multilayer circuit board. Now, we will discuss the difference between PCB and integrated circuits.

What Is IC Or Integrated Circuit Board?

The integration of chips makes an integrated circuit, like chips used in a CPU and motherboard are ICs or integrated circuits. Initially, IC was called an integrated block. You will see the IC soldered on a printed circuit board. In other words, a printed circuit board carries the integrated circuit.
The purpose of the integrated circuit or IC is to integrate an ordinary circuit into a chip. So, if the IC gets damaged, the chip won’t work. But, if the PCB gets damaged, you can replace the components.

Printed Circuit Board and Its Components

PCB has different types, however, today’s circuit board has specific components, such as:
Layout and Circuit: PCB circuit is a tool for conducting between different components. A copper surface becomes the base and power layer. Besides, it involves routing through drawing.
Dielectric Layer In The Board: it is also known as the substrate that contains insulation that lies between the layers and a circuit.
Through-Hole Via: vias are made for conducting and a through-hole via helps multiple layers conduct. The plug-in of a device is a large through-hole. There is also a non-through-hole that helps in surface mounting and fixes screws while PCB assembly.
Solder Mask: The copper surface is not always tinned. Epoxy resin is used to print the non-tinned area to separate the tinned copper to prevent a short circuit. Solder mask has different colors, including black, green, red blue, etc.
Silkscreen or Marking: Silkscreen is used to make legends or mark names and locations of different components. It helps maintain a PCB after assembly.
Finishing: the copper surface has to be tinned or it would get oxidized. The surface finish involves different processes, such as ENIG, HASL, immersion tin or silver, and OSP. You can use any method according to your needs as each finishing method has some pros and cons.

Features of Advanced PCB

High-Density PCB’s
PCB is becoming advanced due to new technology. You will see the HDI circuit boards in all small gadgets. Both installation and ICs are also improving with time.
More reliable
Now, PCB is more reliable than before because we have better testing tools. Moreover, its manufacturing and the end product are of high quality.
Up To Parameters
Each PCB material has certain mechanical, electrical, physical, and chemical properties. You will get a high-performing PCB if its design is according to the standards and design parameters.
Better PCB Production
PCB production has also increased with time due to better tools, design software, and advanced technology. Various standards ensure a high-quality device, such as automation, standardization, management, etc. You will see better equipment to test your PCB to have a high-quality end product.
PC Board Assembly
Assembly has also improved and helps you to have more production than the previous years. Similarly, you can develop complete equipment by assembling different components.
PCB Maintenance
PCB maintenance is also essential, especially, if the assembly gets issues. You can easily replace the damaged parts, restoring the system. Making lightweight, and mini or smart PCB is also easier than before. You can have a device with high-speed signals by maintaining your circuit board.

Features of Integrated Circuit

The integrated circuits were developed by Jack Kilby and Robert Noyce. The integrated circuit is very common in certain industries, such as military, civil electronics, television, communication, radio recorder, computer, etc. It provides the following benefits.

  • Lightweight structure
  • Less lead
  • Small volume
  • Solder joint
  • More reliability
  • Longer lifespan
  • High performance
  • Mass production
  • Low cost

IC is a microelectronic component or device in a PCB. IC technology involves the manufacturing of chips, design technology, processing technology, testing, packaging, design innovation, and mass production.
The integrated circuit is a key part of advanced electronic sand it is the heart of many circuits. You will see at least one chip or IC in every electronic device. IC is a combination of various electronic components, including capacitors, resistors, transistors, etc. These components together make a small chip and are linked to having a common goal. There are different types of ICs, such as

  • Single-circuit logic gates
  • Voltage regulators
  • Open amps
  • Motor controllers
  • 555 timers
  • Microprocessors
  • Microcontrollers
  • FPGAs
  • Many others

There is a complex process of making layers of copper, semiconductor wafers, and several other materials. These materials interconnect to make resistors, transistors, and other parts of a circuit.
Not only IC is too small, but it has very thin copper layers and semiconductor wafers. The layers have very delicate connections. Similarly, The IC die is a very small circuit that is too tiny to connect or solder, so you have to package the die that converts the delicate die into a black chip that you often see.
You can enhance the working life of equipment by using the IC to assemble different electronic tools. It helps you to increase the assembly density many times compared to transistors.
These days, you would see silicon ICs involving semiconductors. So, IC is a device that integrates capacitors, resistors, semiconductors, and other elements that make a circuit perform certain tasks. The device connects wires between these components on the silicon wafer through oxidation, diffusion, aluminum evaporation, epitaxy, and photolithography, and then it is welded in a casing or shell.

Differences Between IC and a PCBoard
Differences Between IC and a PCBoard

What Is IC Package?

IC package helps convert a die into a device to have a connection. Die’s outer connection has a small gold wire to a pad on the package that helps to connect it. The pad or pin is silver and it is an extruded terminal on the IC that continues to connect to a circuit’s outer parts. There are different types of IC packages having different dimensions, installation methods, and a number of pins.
Understanding Pin Numbering and Polarity Marking
You should know that every IC is polarized and each pin is different in its function and location. So, the package must show each pin’s nature and function. Mostly the ICs have DOT or Notch to differentiate the first pin. Like, sometimes only one pin is the first or sometimes both are.
Package Mounting
The mounting of a package on a PCB also varies, it can be SMT or surface mount, SMD, or a through-hole mounting. The through-hole package is often large and easy to manage, and it is created to get stuck through a board’s one side and soldering the other side.
The surface mount package has different sizes, small or minuscule. These packages are created to be soldered to the PCB surface and sit on one side. The SMD package has pins either perpendicular to the chip or extruded out the side, or set in a matrix on a chip’s lower part. Such ICs are hard to assemble with hands and need special tools for this purpose.
Dual In-Line Package or DIP
DIP is an ordinary through-hole IC package having two parallel lines of pins that extend perpendicularly from a black, and rectangular plastic casing.
SMT, SMD, or Surface Mount Package
There are many types of SMT packages and in the case of ICs, you must have a custom PCB having compatible copper patterns to be soldered. You need special automated tools to solder the SMD package.
SOP or Small Outline Package
The SOIC package is the SMT cousin of the DIP as this is what you see when you bend all the pins outward on a DIP, reducing the size. The SOP package is very easy to solder with hands. The spacing between the pins should be 1.27mm or 0.05”.
The shrink small-outline package or SSOP is a small type of SOIC package. Likewise, there are TSOP or thin-small outline packages and TSSOP or thin-shrink small-outline packages.
It is easy to understand the difference between IC and PCB if you know all their features as described above.

Final Thoughts

The integrated circuit is a key part of advanced electronics and it is the heart of many circuits. You will see at least one chip or IC in every electronic device. IC is a combination of various electronic components, including capacitors, resistors, transistors, etc.
The purpose of the integrated circuit or IC is to integrate an ordinary circuit into a chip. So, if the IC gets damaged, the chip won’t work. But, if the PCB gets damaged, you can replace the components. However, PCB and IC work together to help an electronic device function.
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PCB Design

Understanding the PCB Design for Half Adder

Multiple circuits’ combination involves various logic gates to create a multiplexer, encoder, de-multiplexer, and decoder. Such circuits have certain qualities, such as the circuit’s output more depends on the levels which are present at the input terminal.
Such a circuit lacks memory, and the previous input can’t influence the current input. The combined circuits consist of inputs and outputs.
A half adder is an electronic circuit that adds two binary numbers. So, two single binary numbers act as adders in this case. It can return the carry and the output, and the representation in practice involves the XOR and AND logic gates. There are two inputs in a half adder circuit, including A and B, generating the Sum and Carry. So, the number of outputs is also two in this case, like S and C.

Types of Combinational Circuits

  • Half adder
  • Full adder
  • Encoder
  • Subtractor
  • Decoder
  • Multiplexer
  • De-multiplexer

Understanding The Half Adder

Half adder is a digital circuit in PCB that provides an addition to binary numbers. In a half adder, a number’s weight is based on the binary digits’ position. The binary numbers are only from 0 to 1 of which 1 acts as the largest number and 0 as a smaller digit.
The two inputs of the half adder generate two outputs, so it is the simplest electronic circuit in the PCB. The inputs A and B are the bits where addition is required, whereas the Sum and Carry are the outputs abbreviated as S and C.

Half Adder Explained

The half adder circuit has two gates, including XOR and AND, and both have the same inputs. However, each gate generates the output, like XOR generates the Sum and AND generates Carry.

Half Adder Facts

According to engineers’ calculations if both ‘A and B’ inputs are 0, then both outputs like S and C would be 0.
However, if any of the input is 1, then the S or sum will be 1, but the C or carry will be 0.
However, if both A and B inputs are 1, then the S or sum will be 0, and the C or carry will be 1.
The half adder in a PCB performs additions according to the inputs applied.

2-Bit Half Adder

You can have the following combinations, such as

0+0=0

0+1=1

1+0=1

1+1=10

In this equation, 1+1=10, but it should be 2-bit output if rewritten, such as

0+0=00

0+1=01

1+0=01

1+1=10

In this case, the normal output is the Sum, whereas you should consider Carry as a carry-out. It is easy to implement a 1-bit adder through an XOR gate.
If you want to add two 8-bit, you can do it through the full adder because the half adder is suitable for the addition of one binary digit.
For two-binary digits, you will have to reduce the truth table. But, for a three-binary digit adder, the process of addition through a half adder should be done twice. Likewise, a four-digit adder involves another repetition of the half adder addition.
The entire process shows that it is easy to implement, but it takes lots of time.

Half-Adder IC

You can implement the half adder by using the high-speed CMOS digital and logic-based Printed Circuit Board.

Understanding Equation

It is easy to identify the equation of the half adder PCBs through two concepts, such as the Sum of Products, SOP, and the Products of sum, POS. The Boolean system of such PCBs helps find the relations between the inputs applied and the generated outputs.
Designers draw the K maps to find the equation and the maps are based on the facts. The k map has two equations, as it has two logic gates.

The K map for the Carry brings the below facts.
C=A.B
Whereas the K map for the Sum or XOR brings
S= A⊕ B

Applications of A Half-Adder PCB

The basic half adder has several applications, such:

  • It offers additions on the binary bits, and the logic unit and arithmetic lying in the computer need a half-adder circuit.
  • The half adder circuits when combined can produce full-adder circuits.
  • Such logic of half-adder circuits helps in designing calculators. So, the PCB in a calculator prefers a half-adder circuit.
  • The half-adder circuit also helps calculate tables and addresses.
  • Other than additions, the half-adder circuits can also handle different digital circuits’ applications. So, you can consider it a vital part of digital electronics.

Implementing The Half Adder Through An NOR Gate: NOR is a universal gate that helps implement a half adder.

Implementing The Half Adder Through NAND Gate

The NAND is also a universal gate that shows that you can design any type of PC Board through NAND gates. In this type, the carry output is produced through one NAND gate’s output being applied to the input which is another NAND gate. The second NAND gate is AND-gate generated output.

The Sum’s output equation can be produced through the output of the initial NAND, but with A and B inputs. In the end, the outputs generated by the NAND gates are again tried on the gate, producing the Sum’s output.
Hence, the standard adder in a digital PCB is easy to design through different logic gates. However, the addition of multiple bits is hard and it becomes a half-adder’s limitation.

Understanding A Full Adder PCB

The full-adder circuit includes three inputs, such as A, B, and C which add three numbers for input, generating the Carry and Sum. Whereas the number of the outputs is two. The main reason for half and full adders is the addition.
If Carry is produced through a previous addition, you can add it to another, unlike a half adder.

Difference Between A Half And Full Adder

A full adder involves two AND gates, two OR, and two EX-OR gates. Full adder is applicable in digital processors, and additions of several bits.
You have to combine two logic gates for PCB design with a half adder. But, a full adder consists of three gates.
Half adder is required in the electronic devices to calculate additions. But, the full adder is applied to the digital processors to add a long bit.
You can have a high output in full adders. Moreover, they involve a high speed and are very powerful in supplying voltage.
Full adder is also suitable for GPU, or Graphics Processing Unit.
How Are Half Adder And Full Adder Similar?
Half adder and full adder have one thing in common and that is the addition, as both are combinational circuits and don’t need a memory, like sequential circuits.

FAQs

What Is An Adder In PCB?

The digital circuits have different benefits, and if their main focus is to provide an additional, it is called Adder. It has two types, including the half adder and the full adder, depending on its inputs and output. However, the output is called Sum and Carry.
Adder is used in different kinds of processors other than just computers. They are constructed for several numerical elements, such as binary code decimal or excess-3.

Is There Any Limitation Of A Half Adder?

Yes, the half adder has some limitations. Like, it cannot add the carry bit produced from the previous or old bit. So, the half adders can’t perform additions in the case of multiple bits.

What Is A Full Adder In PCB?

A full adder includes three inputs, such as A, B, and C which add three numbers for input, generating the Carry and Sum. Whereas the number of the outputs is two.

Where To Use A Half-Adder Circuit?

PCB with a half adder is used in calculators and digital devices. It has a simple design and you can convert it to a half subtractor.

How Many Types Of Combinational Circuits Are There?

The types of combinational circuits include the half adder, full adder, encoder, subtractor, decoder, multiplexer, and de-multiplexer.

What Are The Uses Of A Half Adder?

A half adder offers additions on the binary bits, and the logic unit and arithmetic lying in the computer need a half-adder circuit. Moreover, half-adder circuits when combined can produce full-adder circuits. The logic in designing calculators. So, the PCB in a calculator prefers a half-adder circuit. The half-adder circuits can also handle different digital circuits’ applications.

Wrap Up

A half adder is an electronic circuit that adds two binary numbers. So, two single binary numbers act as adders in this case. It can return the carry and the output, and the representation in practice involves the XOR and AND logic gates. There are two inputs in a half adder circuit, including A and B, generating the Sum and Carry. So, the number of outputs is also two in this case, like S and C.
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Why printed circuit board manufacturers use plated slots ?

Printed Circuit Board Plated Slots

Slots are holes, which are either plated or non- plated-through. So, plated slots are holes plated in copper. And we use them for electrical connections on the PCB. A through slot is the one that goes to the entire depth of the board, starting from one end to another. Whereas a PCB outline or edge also has plating called side plating.

printed circuit board manufacturers use plated slots for components packaging, however, non-plated slots are also in practice. But, PCB with multiple layers have only plated-through slots.

Why Prefer Plated Slots?

PCB assembly involves different designs and components, and you would often see round holes to accommodate the round components or square as well. A round hole suits a PCB with through-holes. However, certain components are compatible with the blade or rectangular leads, so the round or square holes are not ideal in that case, and this is where a plated slot works.

When the pin size becomes large, the rectangular connectors work with plated-through slots rather than round holes. Like, they are ideal for the DC Jacks. Though you can use the round holes for small connectors and rectangular pins, plated slots are better because they take less space on the PCB, unlike the round holes.

Difference between Plated And Non-Plated Slots

Plated slots have copper plating in the circuit layer, whereas it opens in the solder mask.
On the other hand, non-plated slots don’t have copper plating in the circuit layer, besides, it does not open in the solder mask.

Design of Plated Slots

There is a specific way to show plated holes on the Gerber, like:

    • You have to put the copper pads on the upper and lower solder mask.
    • Then you insert a milling slot in the mechanical layer.

Designers prefer a mechanical layer to put slots in the Gerber and it involves two possible options to do it.;

Use of Flashes Having the Right Size Slot

Drawing a slot with a 0.50 mm thick line, as it helps designers to check it visually to ensure that there is enough tolerance between copper and the PCB edge. Remember that a line’s center is considered the edge of the slot.

Then you have to join the slots with the PCB outline into the Gerber, and it should be parallel to the copper layer. However, the copper layer should also have a PC Board outline to stay on the safer side.
The mechanical layer in this case has different names, depending on the system. It also depends on milling as it should be there. However, you can use another layer in the absence of a mechanical layer. Use the README file to avoid any doubts regarding the right file.

Don’t always define slots in a legend or a copper layer because they could be misinterpreted. Show large slots in the legend or copper layer, however, the outline should be precise. Don’t forget to write the text SLOT in the center.

Creating a Drill File

You can also define the plated slots through drill files as it is a precise way, however not all CAD software allows this option. But, defining through the drill files involves the X and Y or the slot width and length, instead of a complete row of holes that overlap.

Understanding A Small Slot In The PCB

The size of the smallest slot varies, depending on the type of the PCB, like if it’s flex, rigid, or rigid-flex. The width of the smallest slot is 0.50 mm for a rigid and flex-rigid PCB, and the length is often 1.0 mm.

These sizes are so due to more thickness of the PCB, besides, the slots are created through the NC milling that is mechanical. As, the grooving cutter of NC is 0.50 mm and its length is twice the width, like 1.0 mm.

On the other hand, the thickness of the flex PCB is less, and you can make slots through a laser machine. Designers prefer the smallest slot because the bigger slot’s length becomes more which is twice its width.

Milling Of the Cutouts Or Slots

You have to use the round NC grooving bit for the milling of slots in the rigid PCB, and it’s just like the CNC machine. However, the inner corners of the slots are made round instead of sharp. Whereas the PCB edge is created to the center of the border.

Which Industries Can Use the Plated Slots?

Mostly the thick or multilayer PCBs have plated slots, and such boards are ideal for different industries, including aerospace, consumer electronics, computer, and telecommunications. As these slots don’t take much space, they are cost-effective in terms of making. A board with both plated slots and round slots is also ideal for multiple electrical connections.

Frequently Asked Questions

What Is A PCB?

PCB stands for a printed circuit board having different electrical components, holes, and other features. Various industries use PCB boards to provide the electrical signals to run different devices or electronics. A PCB board can be embedded, single or double-layered, or can have many layers like up to 60 plus.

What Is The Definition Of A Plated Slot?

A plated slot is a hole in the PCB with copper plating. It is not round, so it is ideal to accommodate the leads with rectangular pins. You can use such a slot for electrical connections and component packaging
The slot goes throughout the circuit board that’s why we call it a plated-through slot.

What Is Edge Plating?

If plating is done on the edges of a PCB, we call it edge plating. Besides, you can also call it the side plating of a circuit board. It goes from the upper layer to the lower layer of the PCB, extending to an edge of the perimeter.

Which Circuit Board Should Have Plated Slots?

Generally, the multilayered PCBs have slots with plating also known as plated-through slots. However, there are also non-plated slots, depending on the PCB design and its application.

Do I Need A Lot Of Space For Plated-Through Slots?

Plated slots are mostly rectangular, hence they don’t take much space on the PCB like the round slots. So, such slots are ideal when you run short of space on the PCB, and where you need to use the rectangular Jacks.

What is a Copper Layer?

PCB has different layers of which one is a lamination made of copper foil, and it is attached to the circuit board with some adhesive. The copper layer is essential for a two-sided PCB, including copper on both sides. But, PCB boards with more than 60 layers of copper are available by different companies.

What is Solder Mask Layer?

The green color on the circuit board is a solder mask and its surface is called the solder mask layer. The purpose of the solder mask is to cover the exposed copper to prevent users from the electric shock upon contact. Though it is mostly green, other colors are also available.

Final Thoughts

PCB manufacturers use plate slots for components packaging, however, the non-plated slots are also in practice. But, PCB with multiple layers has only the plated-through slots. Certain components are compatible with the blade or rectangular leads, so the round or square holes are not ideal in that case. This is where a plated slot works.

Plated slots have copper plating in the circuit layer, whereas it opens in the solder mask. Non-plated slots don’t have copper plating in the circuit layer, besides it does not open in the solder mask.

The size of the smallest slot varies, depending on the type of PCB, like if it’s flex, rigid, or rigid-flex. The width of the smallest slot is 0.50mm for rigid and rigid-flex PCB and the length is often 1.0 mm. Engineers use cad software to make Gerber files for different types of slots including plated through and non-plated through slots.

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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