All electronic components cannot be soldered by reflow or flow soldering.
What do you mean?
For example, in the case of reflow soldering, since the whole solder is heated, the temperature of the target component will increase, as a matter of course. Also, in case of flow soldering, the component temperature may increase because the component touches melted solder. Therefore, these methods cannot be used to mount components with low heat resistance.
Soldering irons are necessary to solder such components.
That's right. After the reflow or flow soldering process, the components are soldered.
In addition to this, tall components and those that cannot undergo reflow or flow soldering for any reason must be soldered later.
But, this problem has been reduced by component manufacturers' efforts and modification in P.W.B. design.
Other than this, P.W.B. repair work also requires a soldering iron. For example, if a bridge occurs in the reflow or flow soldering process, the bridge must be corrected with a soldering iron. We cannot discard the P.W.B. because of the bridge.
If the component mounted to a P.W.B. is defective, we must remove the defective component, and re-mount a new component to the P.W.B. Even if the technology rapidly advances, it is still difficult to eliminate defects.
Is that right? Well, soldering irons are still required from now on, I suppose.
But, the specifications demanded on soldering irons have become more severe, and will become even more severe in the future.
Hikaru, do you have a mobile phone?
Yes, I have.
Mobile phones have become considerably smaller than those in the past. Why do you think they have become so small?
Let me see, that's because internal components have become smaller, P.W.B. have become smaller, and the component-to-component space has become smaller, too. Oh! Consequently, the soldering tip must be smaller.
That's right. But, if the soldering tip becomes smaller, the amount of heat stored in the soldering tip is reduced. As a result, the soldering tip temperature rapidly drops during soldering. That's true all the more, because P.W.B.s themselves have a multi-layer structure. It is ideal that the soldering tip temperature should not drop even during soldering. But, actually, it is inevitable. Therefore, we need soldering irons with high response speed and excellent thermal recovery characteristics, so that the soldering tip temperature can be instantly restored to a set temperature in response to a drop in tip temperature.
This seems somewhat difficult.
In addition to this, variety of soldering tip shape is also required because the components mounted to P.W.B.s have various shapes.
Well, then, various soldering tips are required to re-touch one PCB.
Yes. We expect that soldering irons that provide high response speed, excellent thermal recovery characteristics and easy soldering tip replacement, such as HAKKO FX-951, will be in demand in the future.
I see. Soldering irons have rapidly advanced too. By the way, how can we remove components with so many leads and those without leads?
These components do have leads on the back. Such components are called "BGA" or "CSP".
The components with many leads can be removed by using a special soldering tip, if they are small. But QFP, BGA and CSP components should be removed by using hot air.
Hot air? Does this mean "high-temperature air"?
It's the same as reflow soldering, isn't it?
Hikaru, today is the last day of our new employee training. Do your best in the field from now on.
Thank you very much.
Soldering is good to learn. I'll study more and more from now on so that I can compete with you.
I'm looking forward to it. By the way, Hikaru, you have forgotten an important application in the soldering iron field.
What is that?
Soldering irons will not disappear as long as there are people like you interested in electronic handicrafts.>
Yes, indeed. We cannot install a reflow machine in our home.
That's right. Ha-ha-ha-ha (Laughing)