A Soldering Aid for Surface Mount Components, by Dave G3VZE

Anyone who has tried to construct equipment using SMDs (surface mount devices) will know the difficulties and frustrations experienced in handling these tiny components. If you attempt to pick up the device with tweezers, it will often squirt out of the jaws travelling at high speed, never to be seen again!  If you do manage to manoeuvre the pesky little thing into position, the chances are that as you apply solder to the first pad, surface tension in the pool of molten solder, will cause the chip capacitor, or resister to stand up on its end like a miniature tombstone. To prevent this amusing little antic, the device needs to be pinned down during the soldering process.

The scrap plastic used in the construction of this device was sprayed white to aid visibility if a component wanders off the board.

Dave G4MVU working on the Finningley SDR at the 2010 Microwave Round Table.

Val was delighted to finish with a working SDR at the 2010 Round Table.

To address these problems, the device in photo 1 was constructed using material from the scrap box. The base and gantry were made of some plastic material about 12mm thick, the two parts being held together by three 5mm screws. The gantry was then drilled 5mm to take a length of 5mm brass rod that had been turned with a fine taper at one end and threaded at the other. The tip of the taper is not a sharp point but is cut off to make a 1mm “flat”, and this flat, when moistened will pick up the tiny components.

Every engineer knows that a 5mm rod will not fit into a 5mm hole, and some time was spent “easing” the fit by polishing the rod with fine wet and dry paper. Eventually a nice sliding fit was achieved with no discernable “shake”.

A golf ball was drilled and tapped 5mm, screwed onto the rod, and finally four rubber feet were glued to the base.

Take care, some golf balls are filled with fluid under pressure and drilling them is not recommended.

Some users have found that the golf ball is not heavy enough, and billiard balls have been used instead.

The device eases the three main difficulties of amateur SMD work; picking up the component, accurately orientating and placing the component, and finally, holding it firmly in place during the soldering operation. To pick the component, the PCB is first placed on the base and the rod lowered onto it. The component is then emptied from its packaging onto the PCB and the rod is lifted with the right hand, by means of the golf ball. The tip of the rod is moistened with a wet finger of the left hand, and the PCB is manoeuvred until the component is directly below the tip. The tip is lowered gently onto the component, and the rod raised with the component stuck to the tip (surface tension working for us on this occasion!) The PCB can now be manoeuvred again until the component is exactly above its intended position on the PCB where it can then be lowered into place, rotating the golf ball so that the component is perfectly aligned with the PCB solder pads. The component is now correctly placed and firmly pinned down, leaving both hands free to solder the first pad; subsequent soldering can be done without the aid of the rod.

In practice several components of the same value can be tipped onto the PCB together, and each one can be picked, placed and soldered quicker than it takes to read the above description.

I claim no originality for this device, and do not recommend the construction or use of this device. I merely describe my own experience in constructing and using it.

Dave G3VZE