Basics of PCB

Basics of PCB:

Overview:

One of the key concepts in electronics is a printed circuit board or PCB. People must often forget to define a PCB. This study will clarify what makes PCB and other common terms used in the PCB world.
In the next few pages, we will discuss the construction of a printed circuit board, assembling specific words, looking at ways to assemble them, and briefly discussing the design process after creating a new PCB.

What is PCB?

The printed circuit board is a very common name but can also be called "printed wiring boards" or "printed telephone cards". Before the advent of PCB, circuits were formed by a complex process of wiring in one place to a point. This has led to common cable crossings and short circuits failures when cable installation begins to age and crack.
A notable development was the development of cable wraps, where a small gauge cord is wrapped around the post at each connecting point, creating a strong gas connection that lasts longer and is more flexible.

As electronics from vacuum tubes and relays were made to silicon and composite circuits, the size and cost of electronic components began to decline. Electronics are becoming more and more popular with consumers, and the pressure to reduce the size and cost of producing electronic products prompted manufacturers to look for better solutions.

This is how PCB was born:

PCB is a summary of the printed circuit board. It is a board with lines and pads that connect various points. In the picture above, there are electrical wiring connectors and various components. PCB allows signals and power to be transmitted between portable devices. Solder is a metal that makes electrical connections between the surface of the PCB and electrical components. Like metal, solder also serves as a strong mechanical adhesive.

Composition:

PCB is like a thick cake or lasagna- there are alternating layers of different materials coated with heat and adhesive so that the result is the same.

FR4:

The basic material, or substrate, is usually fiberglass. Historically, the most common designer of this fiberglass is "FR4". This solid core gives the PCB its durability and durability. There are also flexible PCBs built on flexible high-temperature plastic (Kapton or similar).

You will find many PCBs of different thicknesses; The most common size of SparkFun products is 1.6mm (0.063"). Our LilyPad boards and Arduino Pro Micro boards use a 0.8mm thick board.

Cheap PCBs and perf boards (shown above) will be made with other materials such as epoxies or phenolic, which lack FR4 strength but are less expensive. You will know that you work with this type of PCB when you sell it - they have a very unpleasant odor. These types of substrates are commonly found in low-end consumer electronics. Phenolics have a low thermal conductivity that causes delamination, smoke, and heat when the combined iron is held for a long time on the board.

Copper:

The next layer is a thin copper foil laminated on board for heat and adhesion. For PCBs with two common cases, copper is used on both sides of the substrate. For less expensive electrical gadgets PCB can have copper on only one side. When we refer to a board with two or two sides, we refer to the number of layers of copper (2) in our lasagna. This can be as few as one layer or as many as 16 layers or more.
The thickness of the copper can vary and is determined by weight, in ounces per square foot. Most PCBs have 1 ounce of copper per square foot, but some high-power PCBs can use 2 or 3 ounces of 3 ounces. Each ounce per square meter translates to about 35 micrometers or 1.4 thousand parts of copper.

Soldermask:

The top layer of copper foil is called the solder mask layer. This layer gives the PCB its green color (or, in SparkFun, red). It is covered with a layer of copper to prevent the copper tracks from accidentally contacting other metals, solder, or conductive bits. This layer helps the user sell in the right places and prevents the solder jumper.

A green solder mask is used for most PCBs, closing small tracks but leaving silver rings and SMD pads exposed for sale in the example below.

Soldermask is usually green in color, but almost any color is possible. We use red on almost all SparkFun boards, white on the IOIO board, and purple on LilyPad boards.

Silkscreen:

A white silkscreen layer is applied over the solder mask layer. The silkscreen adds letters, numbers, and symbols to the PCB that allow easy integration with the directions to better understand the board. We often use labels on a silkscreen to show what the function of each PIN or LED is.

The silkscreen is usually white, but any ink color can be used. Black, grey, red, and even yellow silkscreen colors are widely available; it is not uncommon, however, to see more than one color on a single board.

Names:

Now that you have an idea of ​​what a PCB structure is, let's describe some words you may hear when working with PCBs:

Annular ring:

- a copper ring around a hole inserted into a PCB.

DRC:

- design law check. Check your design software to ensure the design is free of defects such as improperly touching, tracing, or drilling very small holes.

Drill hit:

- areas in construction where holes should be drilled or drilled in the board. Inaccurate piercing hats caused by abnormal pieces are a common manufacturing problem.

Finger:

- metal pads protruding from the board's edge, used to create a connection between two circuit boards. Typical examples are on the edges of computer extensions or memory boards and video games based on old cartridges.

Mouse bites:

- another v-score method of dividing boards into panels. Many piercing hinges are stitched together, creating a weak spot where the board can easily break behind the truth. See the SparkFun Protosnap boards as a good example.
A Pada piece of metal is exposed on the board's surface where the part is sold.

Panel:

- a large circuit board made up of many small boards separated before use. Automatic circuit board management systems often have a problem with small boards, and by assembling several boards at once, the process can be greatly accelerated.

Attach stencil:

- a thin, metal (or sometimes plastic) stencil on the board, which allows the solder adhesive to be applied to certain areas during assembly.

Choose a location:

- the machine or process in which the parts are placed on the circuit board.

Flight:

- a continuous brass block on the circuit board, defining the boundaries rather than the path. And it is often referred to as "pour".

Broken with a hole:

- a hole in the board with an annual ring and connected to the board. It may be a connecting point for part of the hole, signal passage, or mounting hole.

Pogo PIN:

- a spring-loaded contact used to make temporary connections for testing or editing purposes.

Re-flow:

- melt the solder to create joints between the pads and the lead part.
Silkscreen - letters, numbers, symbols, and images on the circuit board. Usually, only one color is available, and the adjustment is usually less.

Slot:

- any hole in the non-circular board. Spaces can be filled or not filled. Spaces sometimes add to the cost of the board because they require more cutting time.

Solder paste:

- small balls of solder fixed to the gel area, which, with the help of an adhesive stencil, are applied to the surface mount pads on the PCB before the parts are placed. During reflow, the solder adhesive melts, creating electrical and mechanical joints between the pads and the part.

Solder pot:

- a pot used to quickly move solder boards through parts of a hole. It usually contains a small amount of molten solder when the board is immersed quickly, leaving the solder joints in all open pads.

Soldermask:

- a layer of protective material placed over the metal to prevent short circuits, rust, and other problems. It is usually green, although other colors (SparkFun red, Arduino blue, or Apple black) may occur. It is sometimes called "resist".

Solder jumper:

- a small solder bridge that connects two adjacent pins in a section on a circuit board. A solder jumper can connect two pads or pins, depending on the design. It can also cause unwanted shorts.

Extra mounting:

- a construction method that allows parts to be easily placed on the board, which does not require the track to pass through holes in the board. This is the most advanced assembly method used today, and it allows boards to be filled quickly and easily.

Thermal:

- a small track used to connect the pad to the plane. If the pad is not comfortable with heat, it becomes difficult to get it at a high enough temperature to create a good solder bond. An improperly fitted pad will feel "stuck" when you try to sell it, and it will take an unusually long time to reflow.

Stealing:

- hatching, grid lines, or copper dots left onboard areas with no plane or track. Reduce the difficulty of extraction because less washing time is required to remove unwanted copper.

Tracking:

- continuous copper method on circuit board.

V-score:

- cutting a part of the board, allowing the board to be easily snatched from the line.

With Via:

- a hole in the board used to transmit signal from one layer to another. Tented vias covered with solder masks to protect them from being soldered to. Vias, where connectors and components must be attached, is often installed (revealed) to be easily sold.

Wave solder:

- a method of assembling a metal used on boards with hollow parts where the board is passed over a standing wave of molten solder, which adheres to the prominent pads and parts tracks.

Design Your Own!

How do you do about designing your PCB? The ins and outs of PCB design are too deep for you to enter here, but if you want to get started, here are some tips:

Get a CAD package:

there are many inexpensive or free options in the PCB format. Factors to consider when choosing a package:
Community support: are there more people using the package? The more people use it, the more likely you will get ready-made libraries with the sections you need.

Easy to use:

if it hurts to use it, it will not.

Ability:

some programs limit your design - layer number, sections, the board size, etc. Most of them allow you to pay for a license to upgrade their capabilities.

Portability:

some free programs do not allow you to post or modify your designs. They only lock you to one provider. Maybe that's the right price to pay for luxury and price, maybe not.
Look at other people's buildings to see what they have done. Open Source Hardware makes this easier than ever.
Get used to it, get used to it, get used to it.

Keep expectations low. Your first board design will have a lot of problems. Your 20-day design will have a few, but there will still be more. You can never finish them all.

Programs are important:

Trying to design a board without proper planning in the first place is a futile task.
Lastly, a few words about designing boards for your circuit. If you plan to do more than one or two of a given project, the return of the board design is quite good - point-to-point for cable circuits on the protoboard is troublesome and usually less powerful than purpose-built. Boards. It also allows you to sell your design if it turns out to be popular.

Resources and Progress:

PCBs are just the beginning! From here, we recommend that you check:
  • Soldering 101 - PTH
  • How to study Schematic
  • How to install and set up Eagle PCB software
  • How to Organize PTH PCB: Schematic
  • How to set up PTH PCBs: Board Structure
  • Creating SMD Steps
  • Creating SMD PCBs
  • T³: Attach Your Circuit Boards
  • Electronics Assembly

For more..

By hqt001