Will Reflow Replace Selective Soldering?
Could reflow replace selective soldering? After all, the latter method is cheaper overall. A reflow oven can produce a lot more units in a shorter period of time. Also, with judicious solder ball placement, reflow soldering is actually capable of very decent precision.
Why bother with selective soldering if that’s the case?
Reflow vs Selective Soldering: What’s the Difference?
Given the production capacity and simplicity of reflow oven soldering, fewer companies are resorting to selective soldering for component assembly. It has too many advantages to not do so.
While selective soldering was formerly much more widespread – and hand soldering before that – reflow ovens have become the dominant method of PCB assembly in the industry for those same reasons. A reflow oven is able to churn out many more units over a given period of time.
Additionally, assembly is simplified. Components are placed on board, and a solder ball (usually a mix of solder and flux) is placed at the site of the joint. As the board travels through the oven via conveyor, the solder begins to flow plastically and creates the solder joint.
The board leaves the oven and can either be used in whatever product it is a component of or can be shipped to whomever will use it prior to use by the end consumer.
Selective soldering machines take longer to assemble components. They are generally more expensive. Additionally, many PCB designs don’t require complex soldering to assemble. This is precisely why so many component manufacturers rely on reflow instead of selective soldering.
Except for those that do.
Selective Soldering Is Still Very Much Needed
Selective soldering is merely a soldering method; a tool for accomplishing a task. Like any other tool, there are general purpose tools and there are tools for very specific jobs.
For instance, a claw hammer is a versatile tool that can drive in nails, tacks and do any other job that’s required of many hammers. It also has the claw for prying up nails and so on. It’s a very versatile tool and that’s why most people have one. A bushing hammer, by contrast, is only really useful for texturing stone or concrete. Even though it’s a hammer, it is really only good for a specific task.
Through-Hole Requires Selective Soldering
Similarly, selective soldering is called for when its called for and isn’t when its not. Thus, it can be stated unequivocally that while reflow ovens may have replaced selective soldering machines in some applications, there will always be a need for selective soldering.
A selective soldering machine is called for whenever through-hole components are part of the board being produced. Reflow is only appropriate for SMT components since reflow only solders the top surface of the board. Through-hole components, however, must be soldered on both sides.
Heavy Components Need Selective Soldering
Additionally, selective soldering is also called for when larger, heavier components are attached to the board. A stronger joint is required in this case, which reflow soldered joints aren’t necessarily the best for.
What are some examples, though, of these types of boards? Smartphones are a great example, with the screen and speakers having to be mounted to the board prior to being placed in the phone’s chassis. PCB’s used for electronic control modules for automobiles commonly require selective soldering, as do many boards used in the aerospace industry.
Since some of the largest, most vital industries require use of boards that must be assembled via selective soldering, reflow will never entirely replace it.