In the world of Printed Circuit Board Assembly (PCBA), soldering is the crucial process that brings a design to life. But not all soldering methods are created equal. The two dominant automated technologies, Reflow Soldering and Wave Soldering, serve very different purposes and are engineered for different types of components.
Understanding the key differences between these two processes is essential for designing reliable, cost-effective, and manufacturable electronic products. Today, we at Kingda will provide a clear guide to these foundational manufacturing technologies and explain how we leverage both to deliver perfection.
What is Reflow Soldering? The Heart of SMT
Reflow soldering is the primary method for assembling Surface-Mount Devices (SMD/SMT). It’s the process that enables the incredible miniaturization and density of modern electronics.
The Process in Brief:
- Solder Paste Printing: A precise layer of solder paste is applied to the PCB’s pads using a stencil.
- Component Placement: Automated machines accurately place SMT components onto the paste.
- Thermal Reflow: The board is conveyed through a multi-zone reflow oven. A precisely controlled thermal profile heats the board, melting the solder paste to form permanent, reliable joints as it cools.
- Key Characteristics:
- Heats the entire assembly: Both the PCB and the components go through the oven.
- Ideal for: Small, low-profile components, and complex packages like BGAs and QFNs.
- Primary Application: SMT Assembly.
What is Wave Soldering? The Champion of THT
Wave soldering is the classic, high-speed method for assembling Through-Hole Technology (THT) components. It is renowned for creating exceptionally strong mechanical bonds.
The Process in Brief:
- Component Insertion: The leads of THT components (like connectors and large capacitors) are inserted through holes in the PCB.
- Fluxing & Preheating: The bottom of the board is coated with flux and preheated.
- Solder Wave: The board passes over a wave of molten solder, which flows up into the holes via capillary action and solders all the leads simultaneously.
Key Characteristics:
- Heats only the bottom side: The top side with most components is protected.
- Ideal for: Components with long leads that require superior mechanical strength.
- Primary Application: THT Assembly.
Key Differences at a Glance: Reflow vs. Wave
| Feature | Reflow Soldering | Wave Soldering |
|---|---|---|
| Primary Component Type | SMT (Surface-Mount) | THT (Through-Hole) |
| Soldering Medium | Solder Paste | Molten Solder Wave |
| Heating Method | Heats the entire board assembly | Heats primarily the bottom of the board |
| Key Advantage | Enables high density & miniaturization | Provides superior mechanical strength |
| Common Application | Smartphones, computers, IoT devices | Power supplies, industrial controls |
Mastering Mixed Technology: How They Work Together
The reality of modern electronics is that most complex boards are mixed-technology, containing both SMT and THT components. This requires a manufacturer to be an expert in both processes.
A typical mixed-technology process at Kingda looks like this:
Side 1 SMT Assembly: Solder paste printing and component placement, followed by reflow soldering.
Side 2 SMT Assembly: The board is flipped, and the process is repeated for the second side, again using reflow soldering.
THT Component Insertion: All through-hole components are inserted.
THT Soldering: The board passes through wave soldering (or selective soldering) to complete the final connections.
This complex workflow requires meticulous process engineering to ensure that components soldered in earlier steps are not damaged during subsequent thermal cycles.
The Kingda Advantage: Expertise Across All Technologies
Choosing the right soldering process is a critical DFM (Design for Manufacturability) decision. At Kingda, we don’t just operate machines; we provide engineering-led solutions.
- Process Mastery: Our state-of-the-art facilities include both advanced, 12-zone nitrogen reflow ovens and high-precision selective wave soldering systems.
- Engineering Support: Our DFM engineers work with you to optimize your design for the most reliable and cost-effective soldering process, whether it's 100% SMT, 100% THT, or a complex mixed-technology assembly.
- Uncompromising Quality: With certifications like IATF 16949 and ISO 13485, our quality control is built to meet the demands of the most stringent industries.
From SMT to THT, We Deliver Perfection
Whether your project demands the high-density precision of reflow soldering or the rugged reliability of wave soldering, Kingda has the technology and expertise to deliver flawless results.
Contact us today to discuss your assembly project.
