Keywords: PCB Assembly China, Printed Circuits Assembly

A crucial aspect of the electronic device assembly process is cleaning the Printed Circuits Assembly or Printed Circuit Board (PCB) after soldering and manufacturing. The overall lifetime, dependability, durability, and effectiveness of the device are affected by this.  During production and assembly, PCBs can become contaminated with solder or flux. It also gets contaminated with dirt from the environment or the handling.  Oxides, dust, residues, colophony or moisture, fingerprints, or resin also contaminate the PCB. Resulting in connection damage, circuit damage, decrease in lifespan of the device, failures, and shorts, erosive qualities are exhibited by few contaminants. The life span of the device is extended and the device is prevented from malfunctioning by cleaning this kind of dirt and contaminants.

Eliminating flux and resin residues on populated printed circuit boards is the primary goal of cleaning PCB assemblies. PCB assemblies used in aerospace, telecommunications, automotive, and military industries must be free of any potentially hazardous pollutants. Contaminant-free PCBAs are needed for the following phase such as conformal painting, epoxy staking, or underfill in the production process. It can lead to delamination and poor wetting if flux residue is left on the assembly.

The consequences of not meeting the Cleaning Specifications of Printed Circuits Assembly

While it is being manufactured, a circuit board goes through various processes. During fabrication, it undergoes metal etching and during the assembly, it undergoes the solder application. The potential of leaving various contaminants and residues on the finished board is present in all of these processes. Long-term and short-term troubles with the board can be caused by these residues.

Any contaminants and visible residues on the board could cause concern and will be very obvious in the short term even in cases in which it may not actually be an issue. An example of this is No-clean flux residue. It will leave the board looking although there aren’t any problems with it as if it hasn’t been cleaned properly. Their residue could cause issues in testing for cleanable fluxes that aren’t properly removed during the cleaning process. In the board, they may also result in intermittent functional issues that are tough to reproduce or find.

However, a much larger threat is a threat is posed by the long-term troubles of inadequate cleaning. The reliability of the finished board can’t be compromised by contaminants and residues by not thoroughly cleaning the finished PCB Assembly China.

Ionic contamination is an example of this. They contain molecules that could become conductive When ionic residues remain on a finished PCB and when exposed to moisture. Causing unintended shorts between nets can result in dendritic growth or accelerated corrosion of conductive metal slivers.

Collected on a PCB during manufacturing, some of the ionic residues include:

• Perspiration
• Flux activators
• Salts
• Acids
• Plating chemistries

Functional problems with board-mounted switches and relays, poor adhesion of conformal coatings, and poor contact with interconnects such as sockets, edge connector fingers, and cables are included in additional long-term problems from inadequate cleaning. Of the entire manufacturing process, you can see why PCB cleaning is such a crucial part.

Printed Circuits Assembly Contaminants Types

On a PCB, A huge pollutants range can get collected. Wet Contaminants and Dry Contaminants are the two major categories of these contaminants.

• Wet Contaminants could be soda, waxy oil, grime, or flux.
• Dry Contaminants could be dirt or dust.

The Goal behind Cleaning Printed Circuits Assembly

Cleaning PCBs is not necessary every time. It adds cost and time to the repairing or manufacturing process. Therefore, as to why cleaning PCBs is needed, there must be some justifications. The causes are as follows:

Reliability of PCB

A final product is something that fulfills every demand reliably. This is a final product’s nature. For instance, if there is a failure of a disposable product like a phone key, you won’t lose a life. But, when there is a fault in the heart pacemaker having board failure or some other issue, you can die immediately. Cleaning will be required after any future and assembly rework. For repeatability and efficacy, the process will be evaluated extensively.

Improving the PCB Aesthetic Appearance

The board’s visual appearance reflects on your job if you are a contract manufacturer of PCBs. for your customer’s incoming quality control inspectors, an oily and visible residue near a solder joint may raise red lights. It may appear to be a real defect, such as a blowhole or solder joint void if the flux residue develops spots on the solder joints by charring.

Dendritic Growth Prevention due to Ionic Contamination

They can form a branch or chain known as a dendrite when a current is applied and polar or ionic particles from other sources and flux residue are exposed to moisture in the ambient air. They form an unintentional trace as these dendrites are conductive. With time, current leakage and short circuit are caused by this. 

Corrosion Prevention of Component of PCB

On electrical circuit boards, Acidic flux residues are left. They might cause corrosion of PCB contacts and component leads after drawing in ambient moisture from the air if the residues are not removed with a cleaning process.

Your Expectation Regarding PCB Cleanliness from your PCB Manufacturer

You should get answers to the following to ensure that your circuit board is fully cleaned by your contract manufacturer:

• Is the manufacturer fully versed in standards of cleanliness of PCB manufacturing?
• Are a company culture and facility promoting attention to cleanliness and detail in their operation offered by your manufacturer?
• Is your manufacturer able to attend to any particular cleaning requests?
• For adequately cleaning your circuit board, does the manufacturer have the appropriate processes and equipment?

Conclusion

For future troubleshooting or during the inspection process, a clear and clean Printed Circuits Assembly might also be beneficial. Identifying potential difficulties or locating faults is much easier when the board. All of its components are leftover solder or free of any remaining contaminates. Think about the delivery time, adequate material usage, and cost optimization while choosing a PCB manufacturing partner. You and your manufacturer must be aware of DFA rules, DFM rules, and the latest standards of IPC so that you get the best PCB design.