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EPISODE 5"Soldering is sure to be fun!"


  • Hikaru
  • Mr.Tanaka


Hi, Come in.

Mr. Tanaka, would you show me your electronic handicraft kit now?

Hikaru, you are very excited about this, aren't you?

Of course. Look, I've brought my favorite tool "HAKKO DASH" with me.

I would like you to use my soldering iron "HAKKO RED".

No, thank you. I prefer my DASH iron. Mr. Tanaka, let's start soldering now.

OK. Just a moment. Now where did I put it? It must be around here somewhere. I found it. Here you are.

What is it?

It's a dice.

*Electronic "Dice" Kit
Seven LEDs flash like points of dice.

A dice? Is this a dice?

Yes. If you shake it, the LEDs flash for a while and then stop suddenly. When the flashing stops, the LEDs look like pips on a dice. It can also make a sound.

It seems somewhat difficult.

Such an electronic handicraft kit comes with a printed circuit board. So, it can be easily assembled by inserting components and soldering them.

Printed circuit board

Really? Well, I'll try to make it using my favorite "HAKKO DASH" right away. Oops, I forgot I must ensure ventilation before I start soldering. Then, I put inflammable objects aside and read through the instruction manual.

Can you understand it?

It seems difficult.

Don't worry if you can't understand it right now. You may study it if you get interested in it. Let's work on this today anyway.


Wait a minute. I'll bring the tools we need - nippers, long-nose pliers, cutters, …solder and the iron holder.

You have everything in your home!

I do have a lot. OK. We are ready.

Well, which parts should I solder first?

You had better start with the shorter parts such as jumper wires, resistors and diodes. If you solder taller parts first, it will make it difficult to solder shorter parts.

I see. There are many things to learn about soldering. Well, I'll start with the jumper wires.

As described in the instruction manual, we should use surplus parts of resistor and capacitor lead wires that have been cut off after soldering as jumper wires. Therefore, we should solder the resistor first.

I see.

I'll try first. Bend the lead wires of the resistor with the long-nose pliers into the length that can be fit into the holes in the board. (Photo 1) These holes in the board are called "through holes". Then, insert the bended lead wires into the through holes. (Photo 2) Since the resistor does not have positive and negative polarities fixed, you may insert them in any orientation. Then, turn over the board and bend the lead wires outward near the through holes. This can prevent the component from coming off when it is soldered.

Photo 1

Photo 2

Through hole

Indicates the holes in a board into which lead wires of a component are inserted.
In some cases, it specifically indicates the holes with copper-plated inner surfaces which are used for double-sided boards and multi-layer boards.

I see.

Now, it's time for your favorite HAKKO DASH. The board has printed metal (copper). This serves as wiring between individual components. This printed wiring is called the "Pattern". During soldering, put the soldering tip so that it heats both the lead wire and the pattern. Feed the solder after the temperatures of both parts become slightly higher than the melting temperature of the solder. (Photo 3) In this step, you need to feed the solder gradually from the side opposite to the soldering tip. After soldering is finished, cut off the surplus parts of the lead wires with the nippers. (Photo 4) You may cut off the lead wires before soldering. But this time we'll use the method of cutting off lead wires after soldering. Do you understand?

Photo 3

Photo 4

Yes, it seems easy.

Now you have a try.

Trust me. I'll show you my great technique. Well, first, I bend the lead wires with the long-nose pliers, insert them into the through holes, and then re-bend them. I put the soldering tip on both the lead wires and the pattern, and feed the solder. Finally, I cut off unnecessary parts with the nippers. Finished!

Hikaru, you are good at soldering although you have little experience in it.

I've practiced many times in my mind.

Practiced in your mind?

Yes, I've trained myself so that I can do soldering well.


Now, let's do some more soldering.
Let's hum! Mmmmm ~♪
Well, I finished soldering resistors.

Now let's move on to soldering on the "diode". Be careful about the diode orientation, because it has fixed polarities. Electric current flows only in the direction indicated by the arrow. This diode should be soldered so that the blue line is placed at the top of the arrow.

Is this right? Then, I'll bend the lead wires, and insert and re-bend them in the same way. Then, I put the soldering tip on the relevant parts and feed the solder. Finally, I cut off unnecessary parts. It's so easy. I finished soldering the diodes.
Now, I will solder the jumper wires. That's all.

Shall we mount the buzzer and the power cord too?

Yes, let's.
Do we need to? Solder has already been applied to the tip of this wire. I wonder if I've applied it unintentionally.

No. This is called "pre-tinning", preventing lead tips from loosening. It makes the lead soldering easier.

Photo 5

Is that so? I'll keep "pre-tinning" in mind.

Then, the next is to solder on the capacitors. This thin capacitor is called a "ceramic capacitor" (Photo 6). Since the ceramic capacitor does not have positive and negative polarities fixed, you may mount it without worrying about the orientation. But, this cylindrical capacitor is called an "electrolytic capacitor" (Photo 7). Be careful about the mounting orientation of the electrolytic capacitor because it has positive and negative polarities fixed. Check the "-(negative)" sign on the package and be sure not to mount the capacitor in the incorrect orientation.

Photo 6

Photo 7

What happens if mounting it in wrong orientation?

If the applied voltage is high, the capacitor will break down.

I'll definitely be careful about this. Well, this is the "- (negative)" terminal. I've completed capacitor soldering safely.

Let's do some more soldering.
We'll proceed to LED soldering. An LED is a "light emitting diode". It lights up like a light bulb. Of course, the LED has fixed polarities since it is a kind of diode. Look, you can see a hole printed with an "A" above it. A longer lead wire should be inserted into this hole.

It is interesting that some components have fixed polarities and others do not. Next, we can solder the IC. (Photo 8).

Photo 8

Yes. Be careful not to touch the IC with the soldering iron for too long.

Sure. I position the soldering tip and feed the solder. Position the soldering tip and feed the solder.
OK, I've finished them all. Let's connect the battery now.

Just a moment. I'll check if the soldering is complete.
Well? No, this isn't good enough.

What's wrong?

Not enough solder has been applied to this part and another part. The through holes are exposed. (Photo 9) Then, there is a bridge between this IC lead wire and the adjacent one. (Photo 10)

Photo 9

Photo 10

I see. What should I do in this case?

Heat up the part where is not enough solder again and apply additional solder to it. Be careful not to add too much solder. As for the bridged parts, suck up the solder with the desoldering braid.

I see. Well, I add solder to these parts. Then, I remove solder from the bridge by using the desoldering braid. OK, I've finished it. How is this, Mr. Tanaka?

Photo 12

Photo 11

Good. Now, let's connect the battery.

Thank you. I connect the battery and shake it gently.
Ring ring ring…

Look! It's working.

You got it. You must be very glad to see what you made by yourself working.

Yes. Wow! The electronic handicraft kit is great fun.