I cannot find any information about a practical problem I encounter.

If we don't have crimping tools, when soldering wires to tab terminals with holes as below:

enter image description here

Do we need to pass the wire through the hole before soldering? But sometimes the wire is much thicker than the hole, in that case is it fine to solder the wire tip on the tab terminal's surface?

I couldn't find any examples about this.

  • 1
    \$\begingroup\$ If you really don't want to crimp on the appropriate connectors, you can solder them on, but soldering on those caps is often a really bad idea as they are not made to take that amount of heat. \$\endgroup\$
    – PlasmaHH
    Nov 6, 2018 at 11:32
  • \$\begingroup\$ Motor-run and motor-start capacitors (in my experience) require replacement at least once during the life of the motor. Stick with crimp-on spade connectors, to save effort trying to replace the cap later. \$\endgroup\$
    – rdtsc
    Nov 6, 2018 at 12:55

2 Answers 2


These are Spade terminals, for use with Spade Crimps. You should buy a Crimp Tool to crush these. They are both cheap.

Spade Crimp

Spade Crimp Tool

You should not solder to these terminals, as the relay will be at risk of damage from the heat of the iron. Also, when the relay wears out it will be more difficult to replace.

  • \$\begingroup\$ If you have to do a lot of these connections then your hands will suffer using one of these tools. They require a large amount of force to operate. You can get much better tools that use a ratcheting mechanism to give you a large mechanical advantage. Here's a cheap ratchet type... ebay.co.uk/itm/… \$\endgroup\$
    – user98663
    Nov 6, 2018 at 11:58
  • \$\begingroup\$ You can also solder the crimp connector onto the wire. Have a fan handy to cool it quickly, as the plastic tends to distort. \$\endgroup\$
    – rdtsc
    Nov 6, 2018 at 12:53

If you have no other choice than to solder the wires on directly, then you should try and put the wire through the hole where possible before soldering.

If there is really no way you can do this, then bend the wire in a loop, and place a generous amount of solder on the tab. heat it up and push the wire in, making sure the connection is good and the wire is covered.

Be careful though as using too much heat for too long could cause the tabs to become displaced, and the area around it could melt.

Try and avoid soldering directly to it if possible, but if you really must, then you can do it, as long as you are careful


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