Reflow Oven with Nitrogen Atmosphere Safeguard

2023-10-18

The lead-free era has raised the question of whether nitrogen is needed for reflow. Due to lead-free solder's high flow resistance and poor wettability, especially on circuit boards with OSP (organic protective film bare copper), the pad is easily oxidized, causing problems such as too much exposed soldering angle and the copper pad phenomenon.

It is true that a number of electronics manufacturers do not use nitrogen for operating costs reasons, but the use of nitrogen will become increasingly common as the quality requirements of lead-free soldering continue to improve. In order to ensure nitrogen production flexibility, even if actual production does not necessarily use nitrogen, the equipment should have a nitrogen interface.

The use of nitrogen reflow oven

It is sometimes necessary for us to use nitrogen reflow in order to improve the quality of solder joints. Inert gases, such as nitrogen, serve as protective gases against oxidation of circuit board pads during welding, as well as improving the weldability of lead-free solder by playing a significant role.

With the improvement of the packing density and fine pitch (Fine pitch) assembly technologies, nitrogen reflow has become a leading development direction. It is the nitrogen reflow process and equipment that have improved reflow soldering quality and yield. The advantages of nitrogen reflow are the following:

Enhanced Soldering Quality: Nitrogen helps reduce the oxidation of solder joints, resulting in higher-quality and more reliable connections.
Improved Wetting: Nitrogen promotes better wetting of solder to component surfaces, ensuring better adhesion and conductivity.
Reduced Defects: The use of nitrogen reduces void formation, solder bridges, and other common soldering defects, leading to fewer quality issues.
Consistent Results: Nitrogen creates a controlled and stable atmosphere, leading to consistent soldering results and product reliability.
Reduced Maintenance: With lower levels of oxidation, equipment and components experience less wear and tear, reducing maintenance requirements.
Lower Dross Formation: Nitrogen minimizes dross buildup, reducing the need for frequent solder pot cleaning and minimizing material waste.
Environmentally Friendly: Nitrogen reflow is more eco-friendly as it reduces the emission of harmful fumes and pollutants, contributing to a cleaner working environment.
Extended Equipment Lifespan: Reduced oxidation and corrosion extend the lifespan of soldering equipment, resulting in cost savings over time.
Compliance with Industry Standards: Many industries require nitrogen reflow to meet specific quality and reliability standards, making it essential for compliance.

To enhance the quality of welding, it's crucial to employ a low-activity flux paste that not only elevates joint performance but also mitigates substrate discoloration. However, a drawback to this approach is the substantial cost escalation, which intensifies with the nitrogen volume required. The nitrogen demand varies significantly when you compare the necessity for a furnace operating at 1000 ppm oxygen versus one with only 50 ppm oxygen. In response to this challenge, solder paste manufacturers are dedicated to developing high-quality no-clean solder pastes that can operate effectively in oxygen-rich environments, ultimately reducing the need for excessive nitrogen consumption.

The introduction of nitrogen reflow necessitates a comprehensive cost-benefit analysis, which factors in outcomes such as increased product yield, improved quality, and reduced rework or repair expenses. Fortunately, since the incorporation of nitrogen, we have reaped these benefits without incurring a significant increase in the final cost.

At present, most solder reflow ovens operate with forced hot air circulation, making it difficult to control nitrogen consumption. In order to reduce nitrogen consumption and furnace import and export openings, a very important point is to use a separator, shutter or other device to separate the part of the furnace that is coming in and coming out. When designing the furnace so that the heating chamber is higher than the import and export natural nitrogen layer, the hot nitrogen layer is lighter than air and difficult to mix. By heating the chamber, nitrogen compensation is reduced and purity requirements are maintained.

Inline Nitrogen Vacuum Soldering Oven KD-V8N

The KD-V8N is an advanced vacuum reflow soldering system suitable for a wide range of applications including IGBT packaging, LED eutectic bonding, solder paste processes, high-purity soldering, laser diode packaging, hybrid integrated circuit packaging, tube and shell sealing, MEMS, and vacuum sealing.

The innovative reflow oven platform presented here represents a groundbreaking leap forward in the industry. It embodies a plethora of novel design features, incorporating feedback from our valued customers. These enhancements are aimed at achieving lower Delta T, reducing nitrogen consumption, and extending the preventive maintenance (PM) schedule, all within a compact, low-profile design that offers excellent visibility across your production floor.

We extend a warm invitation for you to explore the advantages of the KD-V8N reflow oven for your production needs. You can visit any of our three conveniently located facilities to run profiles and gather data firsthand. Alternatively, if you prefer a more streamlined approach, send us your most challenging PCB, and we will run reflow soldering profiles and compile the data for you. Our team is dedicated to collaborating with you to tailor your reflow machines to precisely match your unique requirements.