Choosing the Right Flux Remover

Author: Elizabeth Norwood

When it comes to electronic assembly, one of the key considerations for optimal performance is the cleanliness of printed circuit boards (PCBs) and solder joints. Flux residues left behind during the soldering process can hinder the functionality and reliability of electronic components, leading to a range of issues such as poor conductivity, intermittent connections, and even complete failure. That's why choosing the right flux remover is crucial for ensuring clean PCBs.

In this regard, MicroCare has emerged as a leading expert in PCB cleaning solutions. With their extensive knowledge and expertise, MicroCare offers a wide range of flux removers that deliver exceptional cleaning results, enhancing the performance and longevity of electronic devices.

Understanding PCB Materials and Contamination

Different types of PCB materials
One of the most commonly used PCB materials is FR-4, which stands for flame-resistant fiberglass-reinforced epoxy laminate. FR-4 offers high mechanical strength, excellent electrical insulation, and resistance to thermal stress and chemicals. It is widely used in consumer electronics, telecommunications, and automotive industries.

Another popular material is polyimide, known for its superior thermal stability and flexibility. Polyimide PCBs are resistant to high temperatures, making them suitable for applications in aerospace, military, and medical equipment.

Metal-core PCBs (MCPCBs) are designed to dissipate heat effectively. They consist of a layer of thermally conductive material, such as aluminum, between the copper layer and the insulating base. MCPCBs find applications in LED lighting, power electronics, and automotive industries.

However, all PCB materials are susceptible to contamination, which can affect their performance and reliability. Contamination can come from various sources, including manufacturing processes, handling, and external environmental factors. Common contaminants include flux residues, dust, moisture, solder balls and ionic contaminants. 

Common contaminants found on PCBs

Printed Circuit Boards (PCBs) are exposed to various contaminants during manufacturing, assembly, and usage, which can compromise their performance and reliability. Identifying and understanding the common contaminants found on PCBs is crucial for ensuring their proper functioning.

One of the most common contaminants is flux residue. Flux is used during the soldering process to remove oxides and ensure proper solder wetting. Flux residues, a byproduct of soldering processes, are one of the major sources of contamination on PCBs. They can affect electrical conductivity, cause corrosion, and lead to electrical failures. To mitigate flux residue contamination, flux removers are used. Flux removers are specially formulated cleaning agents that effectively remove flux residues and other contaminants, ensuring the PCBs' optimal performance and longevity. However, if not properly cleaned, flux residue can accumulate on the PCB surface, leading to poor electrical conductivity, corrosion, and even short circuits. Flux residue can be particularly problematic in high-sensitivity applications or environments that require stringent reliability standards.

Dust and debris are also common contaminants found on PCBs. These minute particles can settle on the board during manufacturing or assembly processes, or they can infiltrate through openings in the enclosure in field-use situations. Dust and debris can cause insulation breakdown, interfere with signal transmission, and lead to electrical leakage. It is, therefore, essential to maintain a clean manufacturing environment and regularly perform proper cleaning and maintenance on PCBs to prevent dust and debris contamination.

Moisture is another significant source of contamination on PCBs. Humidity in the manufacturing environment, improper storage conditions, or exposure to condensation can result in moisture absorption by the PCB materials. Moisture can corrode metal traces, cause electrical leakage, and degrade the insulation properties of the PCB. Techniques such as conformal coating and moisture-resistant materials can help protect against moisture-related damage.

Solder balls or splatter are tiny pieces of solder flux that can inadvertently form during the soldering process. These solder balls can become dislodged and find their way onto the PCB surface, potentially causing short circuits, electrical bridging, or impedance issues. Proper soldering techniques, such as controlled solder volume and reflow profiles, help minimize solder ball formation and migration.

Ionic contamination occurs when a printed circuit board (PCB), comes into contact with impurities such as salt, acids, sulfates, residues from human handling, or flux activators during its manufacturing or assembly processIonic residues, if not adequately addressed, can result in problems such as electrochemical migration, dendritic growth, and electrical failures. These issues can manifest over time, leading to circuit board malfunctions or even catastrophic failures.

Effective ionic contamination control measures, including proper cleaning and testing processes, are essential for preventing such problems and ensuring the long-term reliability of PCBs. Identifying and addressing these various contaminants, from flux residue to ionic impurities, is crucial in maintaining the performance and longevity of printed circuit boards across diverse applications and industries.

Choosing the Right Flux Remover

When it comes to choosing the right flux remover, consider these factors:

  1. Type of flux residue: Assess the specific type of residue you will be dealing with, such as rosin, water-soluble, or no-clean flux.
  2. Compatibility with materials: Evaluate whether the flux remover is safe to use on the materials you will be working with, as some may be too harsh and cause damage.
  3. Cost: Consider the price of the flux remover, but also weigh its effectiveness and reliability against the cost.
  4. Safety: Prioritize a flux remover that is low in toxicity and non-flammable to promote a safe working environment.
  5. Reviews and Recommendations: Consult professionals in your industry and read reviews to gather insights and make an informed decision about the best flux remover for your needs.

By considering these factors, you can confidently select the right flux remover for your specific requirements.

Download the MicroCare Flux Remover Selection Guide

The Four Steps of PCB Benchtop Critical Cleaning

1. Wet: The first step in the critical cleaning process involves wetting the PCB to prepare it for cleaning. This is done by applying a cleaning solution or flux remover to the surface of the board. The wetting action helps to loosen and dissolve contaminants, making them easier to remove.

2. Scrub: Once the PCB has been wetted, the next step is to scrub the metal surface to remove the contaminants. This is done using a brush or other cleaning tool in combination with the selected flux remover. The scrubbing motion helps to agitate and dislodge the contaminants from the PCB, ensuring a thorough cleaning.

3. Rinse: After scrubbing, it is important to thoroughly rinse the PCB to remove any remaining  contaminants. This step helps to ensure that no residue is left behind, which could interfere with the performance of the board. Rinsing is done using clean flux remover.

4. Dry: The final step in the critical cleaning process is to dry the PCB. This is done to remove any remaining moisture from the board, which could potentially cause damage or affect the performance of the electronics. Drying can be achieved by wiping with a lint-free cloth. It is important to ensure that the PCB is completely dry before further handling or usage to optimize its performance.

In conclusion, choosing the right flux remover is crucial for ensuring the efficiency and longevity of electronic components. By considering factors mentioned above, you can make an informed decision and select a flux remover that will effectively remove flux residues without causing any harm or damage.

Remember, investing in a high-quality flux remover is an investment in the performance and reliability of your electronic devices. So, take the time to research and choose wisely, and enjoy the benefits of a clean and well-maintained electronic system.