How to Build a PCB, Soldering Basics
How to make a PCB at home
To design a PCB at home, wax paper, laser printer, electric iron, steel wool, plastic trays, copper board or PCB, permanent marker (black), etching solution (ferric chloride) and a drill machine is required.
PCB design software is used to draw the schematic diagram of the circuit. There are different types of PCB design software such as Express PCB, Kicad, and Orcad etc.
After drawing the schematic diagram, it is transferred into a layout which can be printed on the printed circuit board. It contains so many connection lines; criss-crossing and connected to the destination points. The resulting figure is known as rat’s nest. These criss-crossed lines can be routed manually as well as using EDA (Electronic Design Automation) tools. The EDA tools will properly arrange the components and also finds correct path for the connection lines. After all these process, at last the layout of the circuit diagram will be obtained.
Step1-4: How to make a PCB
PCB design software helps to draw schematic diagram as well as helps in the drawing of printed circuit boards. The components can be placed like in the schematic diagram such as connectors, switches, LEDs, heat sinks etc. If the circuit diagram contains connectors, place it on the sides for simple connection. Decoupling capacitors can be placed near to the pins. The components must should not be placed at the edge of the board. The components with so many connections must be placed in the middle. Large components must be suitably placed. Otherwise it will make problem while assembling the complete circuit. Use labels to each pin. It will help in future while soldering the components. For e.g.: - GND, VCC etc.
Using a laser printer the layout of the circuit diagram is printed on a wax paper.
According to the size of the layout, cut a copper board. It is the base of the PCB even if it is single layer, double layer or multi-layer board. Single layer board is used to prepare small circuits. One side of the board is copper. In double layer, both sides are copper. The double layer board is mainly used in industries. The multiple layer board contains multiple layers of copper which is mainly used in complex circuits. For e.g. mother board. It is expensive. Remove the oxide layer of copper. For that purpose, the copper board is rubbed with a steel wool. Single layer PCB consists of copper in one side. Place the wax paper which contains printed layout of circuit diagram above the PCB. It must be placed at the copper side of PCB.
Take a white paper and place it above the wax paper. By using electric iron, heat is applied above the wax paper. The printed layout will stick on the copper side of PCB. Now the PCB board contains the layout of the circuit diagram. Cool the PCB board and remove the wax paper slowly. If any part of the layout is broken, then use a permanent black marker to complete the layout.
Step5 :How to make a PCB
The layout is printed onto the PCB. Now take a plastic tray. Fill it with water. Add some ferric chloride powder in the water. Dip the PCB board in this ferric chloride solution (Etching solution) about 30 minutes. This will react with the copper area and removes the unwanted copper from the PCB board. This process is known as etching.
Take the PCB board outside from etching solution and wash it using cold water. The ink is removed using steel wool. The area which is not etched is the copper track which is conductive.
Step7: How to make a PCB Board
Carefully drill the PCB board to put the hole. Then connect the components using the circuit diagram and solder it.
Step8: How to make a PCB
Soldering Electronic Components to the PCB
What is Soldering?
Soldering is a process in which two or more metal items are joined together by melting. A filler material is given to the joint. The melting point of filler material is less. The soldering helps to connect the electronic components permanently. A soldering iron is used mainly for the soldering purpose. The tip of the soldering iron must be clean. The metal part to be soldered is heated by using soldering iron. The solder is melted into the connection.
Solder is metallic glue. It holds the parts together to form a connection. The electrical current flows through the connection. The joint should not move before the solder is cooled. If the soldering parts contain any dirty particles, then the solder will not stick to the equipment. So the parts to be soldered must be clean before soldering. If not, first desolder the parts and then clean it. If the solder is overheated, then a spike is formed and some flux residue will be there.
- Soldering Iron
Soldering iron is the heat source which is used to melt solder. The melt solder flow into joints and helps to solder the components. Soldering iron consists of a heated metal tip and an insulated handle. Electric current is passed through the heating element. To make good solder joints, temperature controlled soldering irons can be used. It consists of a thermostat for controlling the temperature. It can be adjusted and they maintain correct value of temperature.
Soldering Iron (30 W)
For most electronics or printed circuit boards (PCB) 15W to 30W soldering iron must be used.This soldering iron can’t be used for heavy components or thick wire. For that purpose, soldering gun with above 40W has to be used. The soldering iron has small tip, pencil shaped. It has a pinpoint heat source for precise work. The gun has large wattage tip. Its shape is similar to gun. The high wattage tip is heated by directly flowing electrical current into it. If more time takes to heat the joints, then the components will get damaged.
Soldering Iron (40 W) Soldering Iron (300 W)
Soldering Iron Anatomy
It is the part of iron which is heat up and is used to melt the solder for joining the components together. The tip increases the temperature to melt solder and the solder will melt due to the heat of the soldering iron tip. The soldering iron can change the iron tips. It is of different size and shapes. The tip can be changed by unscrewing or just pushing the tip.
The wand holds the iron top of the soldering iron. It is the part which the user can hold. It is made up of insulating material such as rubber. So the heat cannot be transferred and the user can hold this insulating part.
When not in use, the soldering iron can be placed in the soldering iron stand. It is for safety purpose.
It is used to control or adjust the temperatures. The wand is connected to the base. Analog bases and digital bases are available. The analog base contains dial to adjust the temperature. The digital base contains switches to set the temperature. The value will be displayed in the display. Figure shows the digital base and analog base. Some soldering iron consists of a wand with iron tip and a cable to connect the electrical socket. It cannot control or adjust the temperature. The electric current directly reaches the heating element built in the wand.
A wet sponge can be used to clean the iron tip. But it may reduce the lifespan of the iron tip. The iron tip cleaned with wet sponge causes sudden change in temperature. It leads to expansion and contraction of tip and holes may occur at the iron tip. Then it cannot be used for soldering. So brass sponge is preferred to clean the iron tip.
There are different types of solder available in the market. But only few can be used for electronics work. For soldering electronic components, rosin core solder can be used. Solder with .75mm to 1mm diameter can be used for printed circuit board work. It is available in different alloys. 63% tin and 37 % lead is used for electronic components assembly.
- Wire cutter
After components are soldered, wire stripper is used to trim the wire. The wires can be trimmed using wire cutter and then it can be soldered in the PCB board.
It can be used to pull the wire. It may be used for soldering.
It is used to improve electrical connection and mechanical strength. It is a reducing agent which reduces metal oxides at the joints. There are mainly 3 types.
- Water soluble fluxes: - It can be removed with water after soldering.
- No clean fluxes: - It cannot be remove after soldering. But they are non conductive. So it will never cause electric shots.
- Traditional rosin fluxes: - It is available in 3 forms. They are non-activated, mildly activated and activated formulations. Non-activated and mildly activated contain rosin which is combined with acid (any activating agents).?
Figure below shows the solder sucker. It contains a top button. It is pushed down and side button is pushed to suck out the solder. If a large amount of solder is there in the PCB board, then it can be removed using the solder sucker. It consists of a heating element with central hole which is connected to the vacuum pump. It applies heat and it removes the solder from the joint. If any mistakes occur while soldering, it we can easily desolder by using this.
- Soldering tweezers
It is used to melt solder in appropriate place and it can also be used for moving components.
Soldering Process to the PCB
- Clean the soldering iron tip using sponge.
- The soldering iron must be plugged for 2 minutes before use. The soldering iron must be heated to its optimal temperature.
- The electronic component which is soldered is taken and bends its leads. It must be about 2mm separation from the body of the component.
- For soldering a resistor, place the resistor into the PCB board and flip the PCB board. The lead must face to the user. The excess lead is cutoff. The soldering iron holds in right hand and the solder in left hand. The soldering wire must be kept in between the finger tips. About 3 inches separation must be provided from the finger tip.
- The soldering iron and solder bring closer to the base of the lead the resistor and copper track of PCB board. Contact the soldering iron with solder in the junction point.
- Suddenly the solder will melt due to the heat of soldering iron and flow towards the junction. If the junction fills with melted solder then keep the solder away from it.
- By using solder removing vacuum tube, the excess solder can be removed. Usually, the solder turns into liquid form after heating. The excess solder can be removed by the solder vacuum tube.
- Component must not move before the molten solder cooled. After cooled, the lead of resistor is fixed in the PCB board. In the same way, any components can be soldered.
- The molten solder has a volcano shape. If the connection is not correct, then desolder it and try again.
Safety precautions for soldering
- The room must get enough light and ventilation.
- Unplug the soldering iron when not in use.
- Avoid touching the soldering iron. Skin, dress, hair etc keep away from soldering iron.
- Keep the soldering iron in soldering iron stand when not in use. Make sure that it won’t fall off. It must not place on the workbench.
- Take the iron in the plastic handle.
- The power cord must be kept away from the hot iron. If the hot iron touches the power cord, it may cause electric shock.
- The wires to be heated must be hold using tweezers.
- The cleaning sponge must be wet while use.
- After soldering, wash hands using soap and water.
- Lead and other metal fumes are hazardous. So avoid toxic fumes.