how use a Computer-Aided Design (CAD) solution to design PCBs using schematics

You can use a Computer-Aided Design (CAD) solution to design PCBs using schematics. According to the design, the design files or Gerber files are then handed over to the manufacturer who produces or assembles the PCB.

The basic design of PCBs include-

Substrate: The base material of a PCB is known as the substrate. It is what makes the board rigid and durable.

Copper: Each functional side of the PCB is applied with a thin conductive copper layer. The number of sides that will require a copper layer depends if the board is single-sided or double-sided.

Solder mask: The green-colored substance on PCBs is due to the application of the solder mask. It provides insulation to the copper traces so that they don’t come in contact with conductive components.

Silkscreen: Use a white screen as the last layer of the PCB. It contains the labels of different components in the form of symbols and characters.

PCBs can also be of three types-

Rigid PCB made of solid material such as fiberglass
Flexible PCB made of bendable materials such as Kapton
Metalcore PCB made of metalcore
In the next chapter, we will discover the printed circuit board assembly process.

Printed Circuit Boards Assembly Process
3.1 Tools Required
You will need a minimum number of tools if you plan to solder your PCB manually. The things to arrange include-

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Soldering iron or soldering station
Solder flux
Pliers
Wire Cutters
Screwdriver
Volt/OHM meter
3.2 PCB Assembly—Soldering Equipment
You can choose from a wide range of soldering equipment for manual printed circuit board assembly. The most simple ones plug right into the power outlet and don’t have many options for temperature control. You should select a 15 to 30-watt soldering iron for your PCB assembly.

The thermostatically controlled soldering irons can be suitable as they come with options to control the temperature. Some have dials to control the temperature, while others use a magnetized tip with a specific temperature.

It would help if you chose a soldering iron with replaceable tips of different sizes. The bonuses begin to magnetize as you increase the current flow causing the temperature to rise. When magnetism comes down, the heat also reduces.

You may also need a hot air soldering station that uses hot air to melt the solder.

3.3 Types of Solder
You will find different types of solder in the market and choose according to the purpose and application of your project. There are three types of solder used for electronics-

Lead alloy solder
Lead-free solder
Silver alloy solder
Lead Alloy Solder
Solders are made from a combination of lead and tin and may also contain traces of other metals. It is responsible for giving the solder a lower melting temperature which is significant as most electronics are heat sensitive.

Lead alloy solders are defined by the ratio of the weight of tin followed by the weight of lead. For example, it could have a balance of 60:40 or 63:37- the first number represents the amount of container while the second refers to the amount of lead.

You can use both solder types for typical electronic applications. The 63:37 alloy can effectively transform into a liquid state and helps prevent cold solder joints.

Lead-based alloys are used as a standard in the electronics industry but can have health consequences.

Lead-Free Alloys
You may be able to come across lead-free alloys such as the 96.5:3:0.5, which has 96.5% tin, 3% silver, and 0.5% copper. Lead-free alloys are more expensive than lead-based alloys and have a higher melting temperature.

Lead-free alloys create stronger solder joints though they may be brittle.

Silver Alloy Solder
Solders may or may not contain lead. Silver was first used in solders to create more robust and durable solder joints. Silver alloy solders tend to be more expensive than lead-based and lead-free alloys.

3.4 PCB Assembly—Proper Soldering Technique
PCB assembly process. You have to take the help of soldering methods multiple times during printed circuit board assembly. It would help if you used proper soldering techniques to get the highest quality end products possible. Here we will tell you how you can use appropriate soldering techniques during the Bill Of Materials (BOM) of a PCB to get fitted onto aboard.

The proper way to solder is to heat the surfaces that will solder beyond the melting point of the solder. It enables the solder to flow over the surfaces freely. It would help if you also kept a check on the amount of the solder, making sure not to use too much.

You also have to ensure that the surface is heated enough to prevent cold solder joints. It happens when you use too little heat to the surface, and the solder cannot move freely.

The rest of the soldering process is carried out automatically by machines. The reflow soldering uses a series of heaters and cold heaters to melt and solidify the solder and make it firm.

You should ensure that the temperatures are correctly set in the reflow soldering machine. It needs to heat up to 250 degrees Celsius to be able to melt the solder.

The manual soldering technique may be needed when you are dealing with THT components. You have to place the parts by hand and then solder the extra lead or wire on the other side of the board. It has to be done carefully so that the solder or flux does not touch the different components and only in the right place.

It may be complex or challenging to solder PCBs if you are entirely new on the job. would help if you practice first on some small projects and then try your hands on PCB soldering after you are skilled. Would help if you also were careful not to inhale the fume or smoke coming from the flux in the solder.

Now we are going to check out the differences between the processes used to assemble PCBs.

Differences in Printed Circuit Boards Assembly Process
You can use different types of technologies to assemble the electronic components on a PCB. The main methods include Thru-Hole Technology (THT), Surface Mount Technology (SMT), and Mixed technology.

We will discuss the main differences and the process of SMT). This will make it easy for a pick and place machine to easily pick and place the components on the PCB (PCB assembly for each method.

Through-Hole Technology (THT)
THT method of PCB assembly is used for electronic components that come with a wire or lead. The PCB comes with holes that are drilled into it to fit the pieces. The extra charge that goes through the holes is soldered on the opposite side of the board.

THT is used for significant components such as coils and capacitors. It is also used for other plated through-hole or PTH parts that go through the plated through-hole of the PCB. Various PCB components use the holes on the board to transfer signals from one side to the other side of the PCB. For this reason, you cannot rely on soldering paste which will pass right through the holes.

PCB Assembly–Assembly Process
THT assembly makes use of both manual and automatic processes to place the components on the PCB. Proceed as follows –

1. PCB Assembly—Placing Components
Electrical engineers manually place the components on the PCB according to specifications. It has to be done quickly and accurately with full compliance to operation standards or regulations of the THT assembly process for proper functioning.

For instance, it is essential to define the orientation and polarity of electronic components so that operating elements don’t affect them.

2. PCB Assembly—Examining and Correction
You need to check if all the electronic components on the PCB have been placing accurately. It can be done automatically with the use of a transport frame. If you find any errors or mistakes, the engineers can quickly rectify them.

3. Wave Soldering
These electronic components have to be soldered to the board in this step. You can do it manually, but a far more efficient and automated process called Wave soldering can be used.

The PCB is placed on a conveyor belt that carries it inside a special oven which contains molten solder at high temperatures. The solder is applied to the bottom of the board, which covers all the pins at once.

The electronic components are attached to the board with all lead or wire connections.