Building circuit boards essentially requires two-stages: fabrication—or the physical construction of the board architecture—and assembly, where components are added and the PCBA is finalized. The main activity during the latter stage is the soldering of components to the board. The type of soldering depends upon the components utilized. If through-hole technology is used, manufacturers should consider how wave soldering vs selective soldering can impact the time and costs of the optimal board build.
Selective soldering process
Wave Soldering Process
Wave soldering is the original automated PCBA soldering process. As the name implies, the board passes over a wave of solder. Double-sided PCBAs, where components are attached to both the top and bottom surfaces, may require a second pass. This process bonds all components simultaneously. In addition to improved speed, the wave soldering process provides other important advantages:
- Easy setup
- Rapid process
- Low costs
However, when deciding whether to institute this process, there are also disadvantages to consider:
- Requires more materials-solder, flux, nitrogen and power
- Certain components necessitate more masking
- Often results in increased post-assembly cleaning
- Rework is more common to ensure good solder joint quality
As board size decreased and smaller SMDs proliferated, manufacturers required a more precise soldering process to ensure the solder joint quality of these components. Selective soldering was the answer.
Selective Soldering Process
Selective soldering is a slower process than wave soldering; individual components are soldered sequentially by a local wave on an x-y gantry, as opposed to a full wave which hits all solder joints at once. However, further advantages have propelled selective soldering to become the preferred method in many cases. Several significant advantages offered by the selective soldering process are listed below, as well as a few disadvantages to remember.
- Customizable to accommodate different component parameters such as pitch
- Masking can be limited to the board areas that need to be soldered
- No glue needed for SMDs
- Uses less solder and flux
- Can be used for special THT cases where size prevents the use of wave soldering
- Does not require applying excessive levels of heat to board areas that may be more sensitive to high temperatures
- Complex setup
- More time-consuming than wave soldering
- Not efficient for mass production
Selective soldering can offer an advantageous process for many scenarios—especially for today’s small, densely packed boards.
Comparing Wave Soldering vs Selective Soldering
The decision to apply wave soldering vs selective soldering reflects a process choice between efficiency and flexibility—provided that your CM is able to institute both. Selected attributes of each process are described more fully in the table below.
|WAVE SOLDERING VS SELECTIVE SOLDERING|
|Attribute||Wave Soldering||Selective Soldering|
|Need for rework||More likely||Less likely|
As the table above indicates, each method has its advantages. For example, manufacturers can realize significant cost savings by using wave soldering for high-volume production. Alternatively, for prototyping and low-volume manufacturing of complex boards, selective soldering can provide a more cost-efficient process.
|Tempo’s Software-Driven Smart Factory Delivers the Industry’s Leading Custom Turnkey PCBA Manufacturing Services
Tempo Automation, the industry leader in building fast, precise, complex boards for prototyping and low-volume production, utilizes advanced selective soldering to ensure secure solder joints and the highest overall quality for your boards.
And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.