Printed circuit board development - Explained

A printed circuit board, otherwise called PCB, is used to connect and support the electronic components using various tracks, conductive pathways, and signal traces that are made from copper sheets, which are usually laminated on an insulative substance. The conducting layers of a printed circuit board are primarily made of thin copper foil. The insulating layers are laminated using epoxy resin. The board of a PCB circuit is soldered in a green mask. Other colors are also available, but the preferred color is green. Similarly, other dielectrics can also be used instead of an epoxy resin, but that depends on the circuit requirements.

Printed circuit board Assembly

Once the PCB is thoroughly developed, all the electronic components must be connected to develop a functional PCB assembly. It is also referred to as PCA or PCBA. Component leads are inserted in the holes in the through-hole construction. While components are placed on surface or pads in the surface-mount construction. The parts are set and fixed electrically on both the constructions, primarily using a molten metal solder.

Soldering techniques in PCBA

A multitude of methods is used to attach and fix the components to a PCB. One of the most popular ways is “bulk wave soldering,” which is usually done to ensure the machine placement for high volume production. One of the similar techniques is reflow ovens. A reflow oven is also used to place high production volumes. To solder tiny and small parts on the PCB, skilled technicians are employed, and they do it manually using a microscope, a set of tweezers, and soldering iron. There are still certain tiny parts that are impossible to solder using human power, such as ball grid array.

Both of the constructions must be combined in a single PCBA because of the component availability. Some of the components are only available in through-hole construction, while some are only available in surface-mount constructions. Thus, both methods are used collectively.

Printed circuit board testing

After the board gets ready, the printed circuit board assembly services are tested and retested in a variety of ways such as power-off testing, analog signature analysis, and likewise.

When the power is off, an automated optical inspection is done, which ensures the visual quality control at the stage of PCB manufacturing. While the power is turned on, the in-circuit tests are made. These tests include physical measurements such as the frequency and voltage of the PCBA. Several functional tests are done to ensure the PCB performs its designated function appropriately. These tests are facilitated by temporary connections and extra pads. These new connections and pads are isolated using resistors. The in-circuit analysis scans and checks the features of these components. The functionality test is followed by a boundary scan test. This test involves the integration of various ICs on the PCB, which are connected to temporary connections. It is done to check if the ICs are mounted correctly. If the PCB fails any test, the technicians are required to desolder and replace the failed test’s components. This is called rework, in which the PCB development sometimes, might have to start from scratch again.