Methods Are Used in the Assembly of Circuit Boards
A circuit board (PCB) is the foundation for any electronic device. It houses all the components and terminals that will be soldered together to make a functioning circuit. To ensure that the assembled circuit board works properly, it is vital to use the proper soldering methods. Before any soldering can begin, the circuit board must be clean. This step involves using a brush and isopropyl alcohol to remove any dirt or grease. It is also recommended to use a lint-free cloth and isopropyl alcohol to clean the leads of each component as well.
Depending on the type of circuit board, different soldering methods can be used to attach it to the components. One of the most common is called soft soldering, which is ideal for smaller and compact assembled circuit board components. In soft soldering, a tin-lead alloy is heated by a gas torch to melt and act as a binding agent for the circuit board and its components.
In addition to tin-lead alloy, reflow soldering is another popular choice for PCBs that contain through-hole components. In reflow soldering, a mixture of powdered solder and flux is placed over contact pads on the board, which are then subjected to heat that melts the solder. This creates a superior bond between the metal and the pads, making it a good option for connecting through-hole components on a PCB.
What Soldering Methods Are Used in the Assembly of Circuit Boards?
When it comes to smaller, surface-mount components, a reflow oven is often used. This method allows the smallest parts to be soldered directly onto the board without the need for a plated through-hole. It also makes the process more consistent and quicker than other methods.
After the reflow oven has cooled, the board is washed using water that’s kept at about 144 degrees Fahrenheit with a pressure of 45 pounds per square inch. This helps wash away any chemical residue that may be left on the copper surface. It also reduces the time that the board must spend in the etching bath, which saves money and improves product quality.
The next step in the assembly of a circuit board is to apply a protective layer, known as solder mask. This material protects the bare copper from corrosion and provides a smooth surface for soldering. It is typically applied by spraying it on the entire board, but can be selectively placed over areas that are not going to be soldered. After the solder mask has been applied, the circuit board can be further customized with a silk screen layer in white ink. This can include things like component function notations or identifiers, which make it easier for human operators to read the circuit board.
Before assembling the circuit board, it’s important to wear protective eyewear and a respirator and to clean the work area with an industrial cleaning pad and isopropyl alcohol. Lastly, it’s best to start with the smallest pieces and work your way up, as this will keep the board balanced and prevent any uneven tensions that might cause damage.