University of Illinois - Department of Electrical and Computer Engineering

Electronics Services Shop

Elevating A Component Above The Board For Top-Layer Soldering

Suppose you want to install a relay on this board in the area marked in red, and (either intentionally or accidentally) you have designed the board with traces on the top layer going to some of the relay pins. If you were to install the relay normally, you would not be able to solder the pins on the top layer as needed for a good connection on our milled boards. The relay would cover up the pins.

So you instead must install the relay so that it is elevated slightly above the board.

  1. First, place a small U-shaped wire onto the board where the component will go. 22 gauge solid wire seems to work well. This wire will hold the component up off the board while we solder on the bottom layer. Make sure the wire is not covering up any of the holes. It seems like two toothpicks or other thin objects would also work for this.

  2. Place the component on top of the wire.

  3. Tape the component down so you can turn the board over without it falling off.

  4. Turn the board over and solder the component's pins on the bottom layer.

  5. Turn the board back over. Remove the tape and pull the U-shaped wire out from under the component. You now have the component slightly elevated above the board. But it is not yet soldered on the top layer.

  6. Mount the board in a small vice with the edge facing you so that the top side of the board is to the left and the bottom side is to the right. If you hold a soldering iron with your left hand you will want to reverse this. With the soldering iron, heat the pin from the bottom side of the board while applying solder with your other hand to the pin on the top side. Make sure the iron is touching the actual component pin. It may take a little while to get hot enough to melt the solder on the top side. In this fashion you can make a good solder joint on the top side without trying to stick the iron underneath the component.

  7. The installed component should look something like this, with the solder joints visible underneath. Repeat the procedure for all pins that connect to traces on the top side. You may want to solder the other pins, too, for added structural stability. You are done.

Of course, this method may not work if you have pins farther from the edge of the component or hidden behind other pins. In these cases, you may have to redesign the board with no top-layer traces to these pins.

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