If your project involves applications in middle and high-end sectors like automotive, medical, defense, and aerospace, opting for nitrogen reflow during printed circuit board assembly (PCBA) is crucial. But why choose nitrogen reflow soldering for electronics hardware manufacturing? And when should you prioritize nitrogen reflow for PCB assembly? Dive into this detailed guide to explore the benefits and situations where nitrogen reflow soldering proves indispensable.
What is Nitrogen Reflow Soldering?
Reflow soldering involves the controlled heating of solder paste to activate its flux and melt the tin alloy powders. This flux facilitates the wetting of the tin alloy, enabling it to bond with the PCB pads and surface-mount devices. As the solder paste is heated, the flux evaporates, leaving behind molten tin alloy.
During reflow soldering, a chemical reaction occurs between the molten tin alloy, surface finish, and PCB pads, resulting in the formation of an intermetallic compound (IMC). Once the desired peak temperature is reached and maintained for approximately 40 to 70 seconds, the reflow process is complete.
In nitrogen reflow soldering, the reflow process takes place in an environment enriched with pure nitrogen gas. Nitrogen reflow ovens typically maintain a nitrogen purity of 99.99% and are equipped with 8 to 12 temperature zones. Adhering to the GB/T 10565-1989 standard in China, nitrogen reflow soldering ensures that the oxygen content in the oven remains at 4% or below.
Excessive oxygen levels in a nitrogen reflow oven can adversely affect soldering quality and thermal conversion efficiency. Moreover, it poses a fire hazard during the surface-mount technology (SMT) manufacturing process. Therefore, maintaining precise control over
the nitrogen atmosphere is critical to the success of nitrogen reflow soldering operations.
Benefits of Nitrogen Reflow Soldering
Compared to regular reflow soldering, nitrogen reflow soldering provides better wetting and prevents oxidation during the soldering process.
Oxidation Prevention: Nitrogen displaces oxygen in the reflow oven, minimizing oxidation of the solder alloy and metal surfaces. This helps ensure clean and reliable solder joints, particularly for components with exposed copper surfaces.
Improved Wetting: Nitrogen promotes better wetting of solder alloy onto component leads and PCB pads, enhancing solder joint formation and reducing the risk of defects such as solder bridging and insufficient solder wetting.
consists of oxidized solder material, is minimized in a nitrogen environment. This results in less contamination of the solder pot and reduces the need for maintenance and cleaning.
Enhanced Solder Joint Quality: By creating a controlled atmosphere with low oxygen content, nitrogen reflow soldering facilitates the formation of high-quality, void-free solder joints with improved mechanical and electrical properties.
Stages in Reflow Soldering
Pre-heating: Initially, the board undergoes heating to elevate its temperature to the necessary level. This step eliminates any solvents present, which could otherwise compromise soldering quality.
Thermal soak: Next, the flux within the solder paste is activated, while ensuring uniform heat distribution across the board.
Reflow soldering: During this phase, the temperature of the reflow oven is raised to facilitate the melting of the solder paste. The board remains at this temperature to promote proper wetting between the PCB and components.
Cooling: Finally, the board undergoes rapid cooling to establish mechanically robust soldered joints. This ensures the integrity of the connections.
When to Use Nitrogen Reflow Soldering
Oxidation during reflow soldering can lead to failures, especially in the case of double-sided PCBs and components prone to oxidation. Nitrogen reflow soldering presents a solution to mitigate such risks. If your PCB is intended for middle and high-end applications, particularly if it is double-sided or features components susceptible to oxidation, nitrogen reflow soldering for PCB assembly should be considered.
For double-sided PCB assembly, the first and second component-mounting sides undergo separate reflow processes. During the second reflow, there is a risk of oxidation affecting the surface finish and solder of the first side at high temperatures. Nitrogen reflow mitigates this risk by preventing oxidation on the first side while soldering the second side.
In cases of poor wetting of surface-mount devices (SMDs) or the PCB, particularly evident during prototype assembly, switching to nitrogen reflow is advisable. Nitrogen reflow enhances wetting, addressing issues such as poor wetting of QFNs.
For components with big footprints and high-density ball grid arrays (BGAs), nitrogen reflow ensures adequate soldering, minimizing the occurrence of solder voids or open circuits. This is particularly beneficial for components like chip-scale packages (CSP), package-on-package (PoP), BGAs, direct chip attach (DCA), and flip chips.
Furthermore, components with pins plated with materials prone to oxidation, such as silver, nickel, or tin, can benefit from nitrogen reflow. By reducing oxygen contact, nitrogen reflow guarantees soldering quality, safeguarding against oxidation-related issues.
A One-Stop Manufacturer for PCBA Manufacturing
Standard reflow soldering methods are sufficient for typical applications. However, if your products are intended for industries like automotive, medical, defense, and aerospace, or if your PCBs feature OSP coating or are double-sided, Hvttec, a comprehensive PCBA manufacturer, can serve as your solution provider for PCBA and electronics manufacturing needs.
In addition to nitrogen reflow, Hvttec, the one-stop PCBA manufacturer, also offers regular reflow and vacuum reflow soldering options.
Partnering with Hvttec for your PCBA manufacturing needs offers numerous advantages:
- SMT Assembly: Hvttec offers nitrogen reflow, regular reflow, and vacuum reflow soldering options for surface mount technology (SMT) assembly, with no quantity limitations.
- THT Assembly: For through-hole technology (THT) assembly, Hvttec provides independent services for wave soldering and selective soldering.
- Comprehensive Electronics Contract Manufacturing: Hvttec serves as a one-stop solution for electronics contract manufacturing, covering PCB design, fabrication, assembly, conformal coating, IC programming, and box-build assembly.
- Certification and Compliance: Hvttec's PCB and PCBA manufacturing processes are certified with ISO, IPC, IATF, REACH, RoHS, and UL standards, ensuring compliance and facilitating standard qualifications for your products.
- Engineering Support: Enjoy one-on-one engineering support throughout your project, including free design assistance for manufacturing and assembly excellence.
- Sample and Testing: Hvttec provides free complete PCBA samples, IC programming, and functional jig testing for bulk production, ensuring product quality and reliability.
- Specialization in Middle and High-end Manufacturing: Hvttec specializes in middle and high-end PCB/PCBA/box-build assembly, ensuring top-notch quality and performance for your projects.
If your PCB requires nitrogen reflow, entrusting your project to Hvttec ensures satisfaction. For quotes and inquiries, feel free to reach out to Hvttec via email at [email protected].
Conclusion
Nitrogen reflow soldering is an advancement over regular reflow soldering, offering superior wetting and oxidation prevention during the soldering process. If your project targets middle and high-end applications, collaborating with Hvttec, the one-stop advanced PCB and PCBA manufacturer, streamlines your process, saving time, energy, and costs, ultimately leading to success!
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