Steps in PCB A Process

The PCB Company goes through several processes for its creation. They are as follows

Step 1: Solder Paste Stenciling

In the introductory step of PCB assembly, the solder paste needs to be applied to the board. A thin, stainless-steel stencil is placed over the PCB. This allows assemblers to apply solder paste only to certain parts of the would-be PCB.

The solder paste is a greyish substance consisting of tiny balls of metal is 96.5% tin, 3% silver and 0.5% copper, known as solder. The paste is mixed with flux, which is a chemical that helps the solder to bond to the surface. It must be applied to the board at the right places and in precisely the right amounts.

Step 2: Pick and Place

Once the solder paste is applied to the PCB board, the PCBA process moves on to the pick and place machine, a robotic device places surface mount components on a prepared PCB. SMDs account for most non-connector components on PCBs today. These SMDs are then soldered on to the surface of the board.

Traditionally, this was a manual process done with a pair of tweezers, in which assemblers had to pick and place components by hand. These days, thankfully, this step is an automated process among PCB manufacturers. This shift occurred largely because machines tend to be more accurate and more consistent than humans. While humans can work quickly, fatigue and eyestrain tends to set in after a few hours working with such small components. Machines work around the clock without such fatigue.

The device starts the pick and place process by picking up a PCB board with a vacuum grip and moving it. The robot then orients the PCB at the station and begins applying the SMTs to the PCB surface. These components are placed on top of the soldering paste in preprogrammed locations. There are several PCB assembly suppliers that adopt this technique.

Step 3: Reflow Soldering

The solder paste and surface mount components need to be rested for a while until it solidifies.

Once the process concludes, the PCB board is transferred to a conveyor belt. This conveyor belt moves through a large oven. This oven consists of a series of heaters which gradually heat the board to temperatures around 250 degrees Celsius.

Once the solder melts, the PCB continues to move through the oven. It passes through a series of cooler heaters. This creates a permanent solder joint to connect the SMDs to the PCB.

Step 4: Inspection and Quality Control

Once the surface mount components are soldered in place after the reflow process, the assembled board needs to be tested for functionality. Often, movement during the reflow process will result in poor connection quality or a complete lack of a connection. Shorts are also a common side effect of this movement, as misplaced components can sometimes connect portions of the circuit that should not connect.