PCBA

What is PCBA?

PCBA is an founctional PCB board with a lot of different of electronic components attached and soldered fasten on a PCB. PCBA is usually made from a PCB by different assembling methods, such as SMT ( surface mount technology), THT (through hole technolgoy, mixed technology etc.

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How is PCBA made out?

Each stage in the manufacture of a PCBA must be completed perfectly in order to guarantee the PCBA’s quality. We hope that after reading this guide, which details every stage of the production process, you will be inspired.

1. Material preparation

If there are any errors, prepare the SMC, PCB, and exam. Solder pads are flat copper pads that are often tin-lead, silver, or gold plated and have no holes on the printed circuit board (PCB).

2. Stencil preparation

To offer a set place for printing solder paste, stencils are utilized. It is made in accordance with the PCB’s designated solder pad placements.

3. Solder Paste

The first step involves applying solder paste to specific board locations where mounting electronic components is required. The majority of the solder paste is made up of tin, which makes up roughly 96.5% of it, along with other metals including silver and copper. Additionally, flux must be added to the solder paste in order for it to melt and adhere to the board. PCBA makers typically utilize mechanical fixtures to hold the circuit boards and solder stencil in order to apply solder paste in the exact locations and proper amounts. Apply the appropriate quantity of solder paste to the specified area using the applicator, and when the stencil is removed, the solder paste will be in the proper location.

4. Pick and Place COMPONENTS

After the solder paste has been appropriately put to the board, a pick and place procedure is required. Surface mount components should be taken off a reel and placed where they are needed on the board. Additionally, the adhesive strength of the solder paste is sufficient to hold these components in place. This procedure can be carried either manually or automatically, but since a machine completes the full process, it is presently preferred by most manufacturers since it increases accuracy and production efficiency. Additionally, automated select and place guarantees PCBA uniformity from batch to batch.

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5. Reflow Soldering

Reflow soldering is a process used by PCBA makers to harden the solder paste used to link the SMD components to the board after the components have been mounted. So how does it function? The board would first be moved to a conveyor belt and moved through a large reflow oven. In the oven, there are many heaters that heat the boards to a temperature of roughly 250 °C until the solder transforms into solder paste. The board would then be sent through a series of coolers that can cool down the molten solder paste to form a permanent solder bond, allowing for a snug fit of surface mount components on the board.

6. QUALITY CONTROL Inspection

After reflow soldering, it is possible for circuit boards to have issues like bad conneting quality or short circuits; as a result, at this process, manufacturers employ a variety of techniques to check the PCBA and verify the board’s performance. The following two PCBA testing techniques are listed:

6.1 Automatic optical inspection (AOI): Automatic optical inspection is better appropriate for checking large volumes of PCBA orders than manual inspection since it can quickly and accurately discover mistakes and flaws in the board. An autonomous optical machine that is outfitted with powerful cameras that can examine the connection from various angles plays a crucial part in the optical inspection process. Additionally, the machine can examine the various light intensities reflected from solder connections to check the integrity of connections.

6.2 X-ray inspection: This technique employs x-rays to examine PCBA and is ideal for complicated and stacked circuit boards. We can look through the layers and identify all board flaws, including those in the lowest layer, by utilizing x-rays.

7. Insert PTH components

All components are manually put into the board during hand soldering. This is how it works: one person is in charge of placing one sort of component in the required location, after which the board is moved to another workstation, another person places another type of component, and so on, until all of the holes have the proper components in them.

8 Wave Soldering

Wave Soldering is another popular soldering process for through-hole PCB assemblies. When the PTH components are placed on the board, the board would be transferred by a conveyer that passes across a pumped wave or waterfall of solder. The solder smears the exposed metallic areas of the board to create good mechanical and electrical connections.

9. Functional Test

Final inspection, or functional testing, of every PCBA is the last stage of PCBA manufacture. The PCBA would undergo testing under conditions similar to those in which the circuit would function. To test the board’s electrical components, simulated signals and power signals would pass through the PCBA. The board failed the test if the variations of these properties were greater than what was permitted.

9. packing

Waterproof and shockproof packaging bag to prevent moisture and rust

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Surface mount technology (SMT)

SMT is one of most popular PCBA manufacturing technology, why is so popular? Because it is have service advantages as follow:

  1. It can apply smaller size of components
  2. Highly automatic operation by machine, let it be more efficient in production
  3. More reliability in PCBA manufacturing quality
  4. Reduce human work, reduce labor cost
  5. It can make out smaller size PCBA
  6. Both sides of PCB can be attach with components
  7. Make out high components density PCBA board
  8. Component cost is cheaper
  9. Low down production cost.

SMT also have its advatages:

  1. The process complex, the SMT machine operator must be specialist.
  2. Hard to visual inspection
  3. Invest a SMT line is costly
  4. The PCBA make out by SMT hard using in mechanical stress and high temperature environment.

What is SMT?

Electronic components are assembled and produced using surface mount technology (SMT), which adheres them directly to printed circuit boards’ surfaces (PCB). With the use of automated production, more of the assembly labor needed to make a functional board may be finished. A surface-mount device is any electrical component installed in this way (SMD). SMT assembly, in contrast to traditional assembly, does not call for the insertion of components through holes; instead, components are soldered onto the board directly using reflow soldering.

Small tabs on SMT parts were intended to be used with solder to affix SMDs to the PCB’s surface. Components were installed during the Through-Hole Technology period through lead holes that were bored onto PCBs. To hold each item firmly, the holes were sized to accommodate each component. After that, the grip was soldered. SMT considerably shortens the device assembly process since SMDs are swiftly sorted and mounted to the top of the PCB with little to no hole leads. This eliminates the need for hole drilling.

Due to the accuracy needed to produce high-quality surface mount assemblies, the SMT assembly process can be laborious and time-consuming if performed manually (SMA). The majority of SMT manufacturing is thus carried out by automated assembly machines for greater efficiency, especially when production is on a big scale.

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