HowTo: Electronics – Soldering THT parts by hand

The soldering of THT components (THT = Through Hole Technology) is one of the basics you need to build kits, prototypes and Co. Because many electronic components, in particular ICs, are still available in this “push-through” variant.

Although modern/new components are often only offered as SMD variants, this assembly technology – especially in the DIY area – is indispensable.

What you have to consider when assembling printed circuit boards with THT components and how you proceed is described in the following article.

Hints for our lovely english readers: Basically, many of the articles on Nerdiy.de are translations from the original german articles. Therefore, it may happen here and there that some illustrations are not available in english and that some translations are weird/strange/full of mistakes or generally totaly wrong. So if you find some obvious (or also not obvious) mistakes don't hesitate to leave us a hint about that in the comment section. 
Also please don't get confused, that instead of a "dot" often a "comma" is used as decimal separator. 🙂


Safety instructions

I know the following hints are always a bit annoying and seem unnecessary. But unfortunately, many people who knew it "better" from carelessness lost their eyes, fingers or other things or hurt themselves. In comparison, a loss of data is almost not worth mentioning, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Even the coolest project is worth no injury or other annoyance. https://www.nerdiy.de/sicherheitshinweise/


Requirements

Helpful articles:
You can find more helpful information on the basics of soldering in the following article:
Electronics – My friend the soldering iron
Electronics – Loosen, clean and remove components

Required material:

In the following list you will find all the parts you need to implement this article.

Tools required:

In the following list you will find all the tools you need to implement this article.


General procedure

The general procedure for soldering THT components can be summarized almost as a whole.

  1. Insert component correctly from above – i.e. the side with the component printing – through the circuit board.
  2. Secure component. In most cases, a small strip of scotch tape/adhesive tape is sufficient. Sometimes you can also bend the legs through on the bottom to fix the component temporarily in the pcb.
  3. Turn the board over and (only) solder the first contact to the circuit board.
  4. Check the correct orientation of the component again. (At this point, an error is quickly corrected.)
    If needed: heat the single solder joint again to align the component properly.
  5. Solder the remaining contacts.

Resistors/capacitors

To be added.


JST connectors

In principle, JST sockets are only polarity-proof snap-in connectors. They are available in different pitches and as THT or SMD components. This example shows how a JST connector is installed as a THT component.

View of the JST connector with the associated mounting location on a circuit board.
So that the JST connector or its pins can be soldered, they must first be positioned in the associated assembly location and the pins inserted through the circuit board.
So that the JST connector does not fall out when you turn the circuit board around, you should now attach it with a small strip of adhesive tape.
Then you can turn the circuit board over and …
… solder the first contact of the JST connector to the circuit board. It is important that you only solder a contact first, because …
… so you can check from several sides whether the component is currently installed.
The plug should lie flat on the circuit board.
If the plug does not lie flat, you can briefly heat the first soldered contact again and thus position the component correctly. This becomes much more difficult if you have soldered more than one contact right at the beginning.
If the JST connector is flat, you can solder the remaining contacts of the connector to the circuit board.

Headers

In principle, pin headers are the big brother of the JST plugs/sockets. Compared to these, they only have the disadvantage that they are not protected against polarity reversal and that the connectors on the pin headers do not snap into place.

Pin headers are available as both THT and SMD versions.

But soldering the pin headers is just as easy as soldering the JST connector.

View of the pin header with the associated mounting location on the circuit board.
The pin header is inserted through the circuit board from above.
The pin header should be inserted vertically through the board and lie flat everywhere.
Before you can turn the board over, you should secure the pin header with a small piece of tape to prevent it from falling out.
Then you can turn the board over and …
… solder the first contact of the pin header to the circuit board.
As with the JST plugs, you solder the remaining contacts of the pin header later, because …
… first you should check that the pin header is perpendicular to the circuit board and also lies flat everywhere. If not (as in the illustrated case) you can briefly heat the solder of the soldered contact again and align the pin strip correctly while the solder is soft / liquid.
Then the pin header should be inserted in the PCB as shown.
In the longitudinal direction in particular, it is important that the pin header is upright on the circuit board.
Now you can start …
… also connect the remaining contacts of the pin header to the circuit board.
This should look something like this.
Further view.
Further view.

Box connector

Box connectors are again a relative of the pin headers. In principle, these plugs are pin headers surrounded by a kind of “tub”. These are used particularly in connection with flat cable connectors. These can be plugged into the tub connector with reverse polarity protection.

Illustration of the box connector including assembly space on the circuit board.
In order to solder the box connector, it must of course first be inserted into the circuit board.
The box connector should then be secured with a piece of adhesive tape to prevent it from falling out.
Now you can turn the circuit board over and solder the first contact with the circuit board, as with the simple pin header.
Before you solder the other contacts, a possibly oblique socket connector should …
… be aligned.
Then you can also solder the remaining contacts …
…completly.

Post sockets

To be added.


ESP8266

Many of the ESP8266 boards are available either as a variant with a pin header (for example on a Wemos D1 Mini) or as an SMD component. In the first case, you can solder the ESP8266 or its pin headers like a normal pin header. The soldering of the second case – i.e. as an SMD component – is described in the article Electronics – soldering SMD components by hand under the paragraph ESP8266 ESP-12.


IC sockets can save IC lives

Especially when soldering ICs in a DIL housing, there is a small but simple tip that can save you a lot of time and effort in the event of an emergency. For every DIL housing type there are matching sockets that can be soldered in place of the IC. The desired IC is then later inserted into this socket.

If a defect occurs on the IC, it can simply be replaced. So you save yourself the soldering and re-soldering. In addition, the probability that you will destroy or damage the IC due to excessive temperatures during the soldering process is virtually zero.

The (low) additional material costs for the IC socket are worthwhile in any case.

Top view of an 18-pin DIL-IC – also called DIL-18 – including a suitable socket.
Side view.
Side view.
18-pin DIL-IC including a suitable socket on a breadboard. On the right side, the “notch” can also be seen very clearly, which facilitates the orientation or alignment of the component.
In order to solder the IC socket to the circuit board, it must first be …
… inserted through the perforated grid board. Already here make sure that the base is correctly aligned. This also means that the notch on the narrow side of the base is on the correct side. This will also make it easier for you to insert the IC correctly.
The usual procedure: So that it does not fall out when turning the perforated grid board, the base must first be fixed with some adhesive tape.
Then the breadboard can be turned around and …
… the first contact can be soldered.
A possibly wrongly inserted base can easily be “straightened” at this point. Briefly heat the solder of the already soldered contact and align the socket correctly.
As soon as the IC socket is straight and correctly aligned…
… you can add another and …
… solder the remaining contacts of the base to the breadboard.
If you have completely soldered the IC socket, the whole should look something like this.
Now the IC can be inserted into the socket. The IC should be fully inserted into the socket so that it does not fall out when it is shaken.
Side view of the IC used.

THT button

The soldering of THT buttons is particularly easy. This is because they snap into place so well when they are plugged into the assembly site that they are already aligned and can be soldered directly.

View of the button next to its future assembly location.
To solder this, the button is first inserted into the circuit board at its mounting location.
Make sure that the button is “as far as it will go” and just lies on the circuit board. In this position, it should be stuck in the board due to the slightly jamming contacts. At least so firmly that it no longer slips until soldered.
Now you can turn the board around and …
… solder the first contact of the button.
At this point, check again to be sure that the button is straight.
If everything fits, you can also solder the remaining contacts.
Side view of the soldered button contacts.

SMD button

The soldering of SMD buttons is described in the article Electronics – soldering SMD components by hand under the paragraph SMD buttons.

 


5mm and 3mm LEDs

To be added.


Close and open the solder jumper

Solder jumpers are a great way to install modifications or adjustable options on the circuit board in advance without giving up the “professional look”.

Various options and settings can then be activated or deactivated by opening or closing this solder jumper.

The solder jumper is closed by placing or removing a solder bridge over its two contacts.

Ansicht des – noch geöffneten – Lötjumpers “SJ4”.
To close this you should first put some solder on the first and …
… then on the second contact.
These two contacts can then be connected very easily by heating both contacts with the soldering iron and letting them fuse together.

Additional information

https://www.computerwissen.de/hardware/pc-tipps/artikel/wichtige-massnahmen-zur-unfallverhuetung-beim-loeten.html


I hope everything worked as described. If not or you have any other questions or suggestions, please let me know in the comments. Also, ideas for new projects are always welcome. 🙂

Fab

P.S. Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you appreciate it that I share these information with you, I would be happy about a small donation to the coffee box. 🙂

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