The printed circuit board (PCB) is a fiberglass or reinforced glass plastic board with copper traces on one side. Electronic components complete the set up and it is what an assembly company refers to as printed circuit assembly (PCA) or PCB assembly (PCBA). Before starting assembly though, there are materials, tools, and equipment to prepare.
What are these materials, tools, and equipment? Each assembly company uses different tools and equipment to produce a specific electronic product. However, the materials, tools, and equipment listed below are generally found in any assembly team, regardless of whether they are using electro-mechanical or manual assembly.
Materials Essential in a PCB Assembly
•Printed Circuit Board
It is the most important material to prepare. Without it, the assembly process cannot proceed. Each PCB is designed and customized accordingly.
They give life to a PCB. There are two categories of electronic components: active and passive. Each PCBA is a combination of active components, passive parts, and integrated circuits. Even the simplest electrical device such as a flashlight has a PCB and other electronic components attached to it. They are the flat (usually black in color and are called integrated circuits by engineers), tube-like things attached to a green, blue, or orange flat board inside your electronic device.
It is a tacky solution, usually gray in color, used to glue an electronic component on the surface of the PCB. It keeps the components in place while the PCB goes through the soldering equipment. Typically, the solder paste is used in an SMT (surface mount technology) PCB assembly. Solder paste has different compositions depending on purpose and type. It could be classified into three types: rosin based, water soluble, and no-clean. Rosin is an extract from a pine tree. Rosin-based solder paste usually needs cleaning after the assembly process. Water-soluble pastes are made from organic raw materials such as glycol. On the other hand, no-clean solder pastes are made from resin and require no cleaning process after assembly.
It is a stainless plate with cutout patterns and is customized according to the product being assembled. Stencil is an integral part during assembly because it measures the right amount of solder paste to be deposited into the surface of the board (or the solder pads). It simplifies and fastens the assembly process. With proper stenciling, error decreases significantly.
Other materials include adhesive and cleaning products for packaging and cleaning (if necessary) of the finished product,
Tools Used During Assembly
•Soldering iron/Soldering Station
It is used to solder components to the PCB and is typically used in a manual assembly. In the SMT assembly method, a soldering iron is necessary during rework process and when the components are too small for a machine to place in the PCB surface. A soldering station is an upgraded version of a soldering iron. The tool has a stand and a controller that regulates temperature.
These simple tools are used to hold components. Direct contact with the electronic components is not advisable since humans have static energy that may render the components defective.
•Vacuum Pickup Tools
These tools are useful when picking up misaligned components.
Other tools may include pliers, shears, scissors, and cutters. These tools are essential in cutting excess wires and are mostly used during rework or manual assembly.
Equipment Needed in an SMT Assembly Process
Typically used during the SMT process, a pick-and-place machine mounts components onto the surface of the PCB. It is a sophisticated machine that is part of an integrated system and is controlled by a computer.
Reflow equipment could be a separate machine or could be integrated with a pick-and-place equipment. The equipment is used to solder components that are mounted on the PCB’s surface. It melts the solder paste that is deposited between the components and the PCB. It acts like a soldering iron except that it is used only in an electro-mechanical process (such as the SMT technology).
Every PCB assembly is unique and may require anything from simple tools to the most sophisticated machine. The above mentioned materials, tools, and equipment are merely a few examples but they are the most essential ones.