PCB Terminology List in PCB Design-PCB Glossary

Introduction to PCB Terminology

Printed Circuit Board (PCB) design involves a wide range of technical terms and acronyms. Understanding this PCB terminology is essential for effective communication among PCB designers, manufacturers, and clients. This comprehensive PCB glossary covers the most commonly used terms in PCB design, manufacturing, and assembly.

PCB Design Terminology

PCB

A Printed Circuit Board (PCB) is a flat insulating board that supports and connects electronic components using conductive tracks, pads, and other features etched from copper sheets laminated onto a non-conductive substrate.

Schematic

A schematic is a symbolic representation of an electrical or electronic circuit. It shows the components of the circuit as standardized symbols and the connections between them.

Footprint

A footprint, also known as a land pattern, is the arrangement of pads and holes on a PCB that corresponds to the pins or leads of a particular component. The footprint ensures proper connection between the component and the PCB.

Gerber File

A Gerber file is a standard file format used to describe the printed circuit board images in PCB fabrication. It contains information about the copper layers, solder mask, silkscreen, and other features of the PCB.

Drill File

A drill file, also known as an NC drill file or Excellon file, contains information about the location, size, and type of holes to be drilled in a PCB. This file is used by CNC drilling machines during PCB fabrication.

Netlist

A netlist is a text file that describes the connectivity of a PCB or electronic circuit. It lists all the components and the nets (electrical connections) between their pins.

BOM

A Bill of Materials (BOM) is a comprehensive list of all the components, parts, and materials required to manufacture a product, such as a PCB assembly. The BOM typically includes part numbers, descriptions, quantities, and sometimes supplier information.

PCB Manufacturing Terminology

PCB Substrate

The PCB substrate is the insulating material that forms the base of the printed circuit board. Common substrate materials include FR-4, Rogers, and polyimide.

Copper Clad Laminate

Copper clad laminate (CCL) is a raw material used in PCB fabrication. It consists of a thin layer of copper foil bonded to one or both sides of an insulating substrate material.

Etching

Etching is the process of removing unwanted copper from a PCB to create the desired conductive pattern. The most common etching methods are chemical etching and plasma etching.

Solder Mask

Solder mask is a protective coating applied to the copper traces of a PCB to prevent oxidation and provide electrical insulation. It also helps to prevent solder bridges during the soldering process.

Silkscreen

Silkscreen, also known as legend or nomenclature, is the layer of text and symbols printed on a PCB for identification and assembly purposes. It typically includes component outlines, reference designators, and logos.

Vias

Vias are small holes drilled through a PCB to connect different layers of the board. They can be through-hole vias, blind vias, or buried vias, depending on their starting and ending layers.

Plated Through Hole (PTH)

A Plated Through Hole (PTH) is a hole in a PCB that has been electroplated with a conductive material, typically copper, to create an electrical connection between layers.

Surface Mount Technology (SMT)

Surface Mount Technology (SMT) is a method of assembling electronic components directly onto the surface of a PCB without the need for through-hole mounting. SMT components are smaller and allow for higher component density compared to through-hole components.

PCB Assembly Terminology

Reflow Soldering

Reflow soldering is a process used to attach surface mount components to a PCB. The board is heated in a reflow oven, causing the solder paste to melt and form a permanent connection between the component leads and the PCB pads.

Wave Soldering

Wave soldering is a process used to attach through-hole components to a PCB. The board is passed over a molten solder wave, which selectively solders the component leads to the PCB Through-Holes.

Pick and Place

Pick and place is an automated process in PCB assembly where a machine picks up surface mount components and places them onto their designated locations on the PCB with high precision.

Stencil Printing

Stencil printing is the process of applying solder paste to the PCB pads using a stencil. The stencil is a thin metal sheet with openings that correspond to the PCB pads, allowing for precise solder paste application.

Inspection

PCB Inspection is the process of examining a PCB assembly for defects, such as component placement errors, solder joint issues, or contamination. Common inspection methods include visual inspection, automated optical inspection (AOI), and X-ray inspection.

Rework

PCB Rework is the process of repairing or modifying a PCB assembly to correct defects or implement design changes. This may involve replacing components, repairing solder joints, or modifying the PCB itself.

PCB Terminology Table

Frequently Asked Questions (FAQ)

1. What is the difference between a schematic and a PCB layout?

A schematic is a symbolic representation of an electronic circuit, showing the components and their connections. A PCB layout, on the other hand, is the physical design of the printed circuit board, which includes the placement of components, routing of traces, and creation of footprints.

2. What are the different types of vias in a PCB?

There are three main types of vias in a PCB:
1. Through-hole vias: These vias go through all layers of the PCB, from top to bottom.
2. Blind vias: These vias start from either the top or bottom layer and terminate at an inner layer, without going through the entire board.
3. Buried vias: These vias connect two or more inner layers without reaching the top or bottom layer of the PCB.

3. What is the purpose of solder mask on a PCB?

Solder mask is a protective coating applied to the copper traces of a PCB. Its main purposes are:
1. To provide electrical insulation between adjacent traces and components.
2. To protect the copper traces from oxidation and corrosion.
3. To prevent solder bridges from forming during the soldering process.

4. What is the difference between reflow soldering and wave soldering?

Reflow soldering is used to attach surface mount components to a PCB. The board is heated in a reflow oven, causing the solder paste to melt and form a connection between the component leads and the PCB pads.

Wave soldering is used to attach through-hole components to a PCB. The board is passed over a molten solder wave, which selectively solders the component leads to the PCB through-holes.

5. Why is PCB inspection important?

PCB inspection is crucial to ensure the quality and reliability of the PCB assembly. It helps to identify defects, such as component placement errors, solder joint issues, or contamination, which can lead to malfunctions or failures in the final product. By detecting these issues early in the manufacturing process, corrective actions can be taken to minimize rework costs and improve overall product quality.

Conclusion

Understanding PCB terminology is essential for effective communication and collaboration among PCB designers, manufacturers, and clients. This comprehensive PCB glossary covers the most commonly used terms in PCB design, manufacturing, and assembly, providing a valuable resource for both novice and experienced professionals in the electronics industry.