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Every profound electronics manufacturer knows that the quality of their PCB Assembly (PCBA) is defined by the cleanliness of their printed circuit board (PCB). As a result, they invest in training, hiring, and equipping. They call it "quality control," They invest millions of dollars on tools to guarantee complete inspection.
PCBA cleanliness is a significant factor when it comes to the manufacturing process. Items produced following these standards have an enhanced production cycle and make the products free from failure.
Have you ever considered the importance of keeping automated test equipment clean? This blog will discuss some basic guidelines to ensure optimum data integrity when performing tests with your automated testing system.
It's essential to have written standards for cleanliness when assembling printed circuit boards (PCBs) to ensure that components are correctly handled and avoid damaging them. In addition to following a general plan of action, it's essential to follow specific rules when taking parts.
PCBA cleanliness standards vary by company and industry, but everyone should follow a few general rules of thumb.
Most importantly, the more you handle your PCBAs, the more contaminants you will get on them—and the more crosstalk you'll have between layers. Your PCBAs should be taken infrequently, preferably by machine whenever possible.
What's the worst thing to do? Touch it with your fingers. That's all we need to say about that. Chips shouldn't touch anything else. If they do, wipe them down with a cloth or paper towel before handling them again.
Use tweezers for handling chips, resistors, and other parts—if you're working in an assembly line and building up a handful of parts at once, keep them separate on their little plastic tray so they don't get mixed up.
There are standards for PCBA cleanliness because it's essential to prevent cross-contamination in the manufacturing process, particularly when people will be deliberately ingesting the product.
That's right: many of these parts will end up in your mouth, so they need to be cleaned properly after they're manufactured and before they're packaged up for distribution.
There are plenty of steps to prevent contamination, but the first is cleanliness at the source, which means that PCBA manufacturers need to ensure that their manufacturing floor is properly cleaned each day.
A recent study showed that even a tiny amount of dirt on a surface could contain enough bacteria to make thousands of people sick over time.
When you add that PCBA manufacturers can have hundreds of employees working on different boards all day long, it's clear why there are standards for cleaning.
One of the biggest reasons for PCBA cleanliness standards is to prevent component corrosion. The most common example is when the excessive flux is used in a solder paste containing rosin-based changes such as ammonium phosphate and ammonium chloride.
These two fluxes can cause corrosion on copper surfaces and short-circuiting problems.
Another important reason for PCBA cleanliness standards is to prevent short circuit failures caused by poor solder joint quality.
This is especially important if you're using lead-free solder, which has a lower melting point than the traditional tin/lead solder alloy used for decades before 2002 when the European Union began banning lead from electronics products sold within its borders.
Since then, lead-free solder alloys have been used in electronic assembly but have been known to have poor wetting characteristics on some substrates.
This means that they don't flow appropriately during reflow soldering processes, leading to shorts between components or boards if not properly cleaned before reflow soldering.
PCBA is made from various components, such as metal, plastic, and rubber. If these components are not cleaned properly before being assembled, the metal parts may cause breakage of the wire and other damages.
When PCBA components are assembled, they generate heat mainly due to the high power consumption of electronic devices.
To ensure that the device's temperature does not exceed a safe level, the PCBA must have an excellent thermal conductivity so that heat can be dissipated quickly.
If the PCBA does not have good thermal conductivity or there are air gaps between each component, heat will be trapped in these areas, which can cause overheating and damage to some parts on the board.
As mentioned above, overheating may cause some damage to a PCBA due to its poor thermal conductivity of air gaps between each component. This means you need to spend more time repairing your product or replacing damaged parts instead of usually using it.
Besides, an overheating device usually means something wrong with its power supply or its hardware itself - both scenarios suggest that there may be some problems with your product's performance.
There are two different PCBA cleanliness standards: functional cleanliness and cosmetic cleanliness. The former refers to the ability of the PCBA to function correctly, while the latter refers to how well the PCBA looks.
The two standards are interrelated—how can a PCBA be functional if it doesn't work correctly?—but they aren't the same. Operating cleanliness involves the ability of the circuit board to accomplish its intended purpose without interfering with other components or failing.
Cosmetic cleanliness is about whether there are stains, scratches, or discolorations that affect how it looks. When you're manufacturing a new product, you'll need to test for both kinds of cleanliness.
You can perform tests for functional cleanliness during assembly when you'll have access to the circuit board and its components and operate it in real-time.
However, you may not have access to every part of the board for visual inspection until after assembly is complete, so you'll need to conduct cosmetic cleanliness tests once everything is put together as a unit.
There is a lot to think about when building a printed circuit board (PCB) for your project. When looking at a PCB under magnification, it is possible to see dirt on the surface of the copper.
This dirt can come from several sources—some natural and some manufactured. The rule isn't just that there be no dirt—it's that there be no dirt that isn't found in the human body.
This means no particles with sharp edges or corners, like metal filings or sand. It also means no particles with hard surfaces within the human body, like plastic or glass. The idea is that there be no foreign objects that could harm a patient if one were to enter their bloodstream as part of a medical procedure.
PCBA cleanliness test methods determine the efficacy of cleaning and disinfection. The primary test method for determining the disinfectant properties of a liquid chemical is the AOAC Official Method 965.28, which uses a swab to wipe a surface on a Printed Circuit Board (PCB). Samples from this wipe are then inoculated with specific microorganisms to determine biocidal activity.
In addition to this standard, several modifications of this test method are used depending upon the industry or PCB type. One commonly used change is the AOAC Official Method 966.11, which uses shorter exposure time and lower inoculum size to more accurately reflect biocidal activity in real-life situations.
Another modification is the AOAC Official Method 966.12, which uses a small volume of rinse water and no swab to test biocidal activity against Pseudomonas aeruginosa and Acinetobacter calcoaceticus.
The IPC-610 standard states that the visual inspection of a surface must be performed by an individual who is trained and experienced in the assessment of PCBA's. Visual inspection is used to detect contamination that can inhibit or prevent the proper functioning of electrical devices.
Visual inspection should be performed at least once per shift by a trained and experienced individual. The visual inspection must include all areas of the assembly process, including but not limited to: pick and place, wave solder, spin bake, rework, and final inspection. However, the visual inspection does not replace environmental testing specified in IPC-610.
The standards are divided into three parts – PCB Assembly, PCB Manufacturing, and Assembly and Testing – which include the following:
This test is performed through a high frequency of up to 18 mega Hertz. It helps determine any possible defects on the circuits, such as solder mask defects, voids, and cracks.
This test is done on the PCBAs at a frequency of less than 500 Hertz. It is used to determine whether any possible vibrations or noises are generated by the electronic components when they contact other members.
This test is performed on the PCBAs to determine whether they can sustain temperature fluctuations for at least 1000 cycles.
This test is performed on the PCBAs to determine whether they can withstand salt spray corrosion over one year or more at 55 degrees Celsius or above.
In the end, the truth is that manufacturers are going to have to start making their components cleaner, using better polishing techniques and chemicals.
These changes won't happen overnight, but they will help in the long run. And for now, we'll have to be content with keeping our PCs looking as clean as possible.
Then all you need to do, it seems, is scrub your PCBs with a very gentle liquid soap and wash them in warm, soapy water. And while we wouldn't go as far as to say that PCs are now clean enough to be used as chips in electronics, they're certainly no longer toxic either.