The JA3TBW Solder Guide

Table of Contents

Soldering I
Soldering II
Soldering III: Tinning Stranded Wire
 Soldering IV: Popular RF Connectors
Soldering V: RCA and Motorola Plugs
Soldering VI: Resistance Soldering
Soldering VII
JA3TBW Solder Guide
Soldering Kinks
Vinther Fingertip Soldering Iron

As mentioned in our "Hints and Kinks," SKTF, Spring l982, Mike Bhagwandas (JA3TBW) of Kobe, Japan, invented this guide. Since that time, our lab has done considerable experimenting with its use as an aid to soldering short-legged components which have poor "landmarking" features into printed boards. Blind subjects who have built our prototype "kit sets" have found this instrument indispensable when soldering the IC sockets and trim pot. So that you can enjoy the fruits of this research, we have attached the described version to each copy of the magazine; please wear it in good health.

The material we settled on is stainless steel, and we did so for the following reasons:

  1. It will never char and contaminate the iron.
  2. If "acid" or "stainless steel" flux is not used, it is unlikely that solder will adhere to the tube.
  3. Stainless steel has poor heat conductivity.
  4. The resultant device can be of small diameter; it is available having a wall thickness of 0.009 inches.
  5. This tubing is commonly available, sometimes being known as "hypodermic tubing."

Specifically, we purchased "Hypoflex" seamless thin-walled stainless steel tubing of Grade 304; its dimensions are 0.072 inches outside diameter (o.d.), 0.009 inch wall thickness, giving us what they call a "theoretical inside diameter" (t.i.d.) of 0.054 inches. Unfortunately, this product only comes in bundles of l20 feet at 62 cents per foot. However, a similar product can be gotten from "Small Parts,"* in 6, l2, and 24 inch lengths. They have two types available: HTX-l5 Hypodermic Tubing with a 0.009 inch wall, and HTX-l5TW "Thin Wall" tubing with the same outside diameter of 0.072 inches and a wall thickness of 0.006 inches. The former is $2 per foot; the latter is $l.20.

The size was chosen so as to accommodate solder of approximately 0.03 inches; the tube has plenty of room to spare for wrinkles in the solder to pass freely through it.

Two brands of solder can readily be gotten with these dimensions. The first is Kester, 604A33-lSN6066.03l44, available from Marshall Industries.* This Kester solder, which has a diameter of 0.03l inches, is also available from Mouser Electronics* under their number 533-24-6040-27. Finally, 0.028 inch "Multicore" solder is available as Ersin number SN60 22SWG. The Kester is preferable, since "Multicore" solder tends to contain an overabundance of flux, thus causing gumminess and stickiness in the tube.

The tubing has such a thin wall as to afford being "parted" with a file, especially knife-shaped or three-cornered files. After sectioning off a piece (4 inches being a popular length in our trials), square off the ends with a file; then de-burr the inner edges with the tip of a file or with a drill bit. (We have done all of this to the 4-inch piece you've received.)

For unclogging these units when solder gets lodged inside, a No. 55 drill bit is a handy addition. This bit is 0.050 inches in diameter, and will comfortably ream it out without galling.

One final note on making your own customized version: You may wish to devise a handle so as to afford better control. We would be very interested in the schemes you come up with along this line. A small "shaft stop" with a set screw is included with your guide. Used as an adjustable collar, the shaft stop can be secured to the tube just below your hand so as to promote stability in holding the tube against the work. (The shaft stop is available from Player Piano Company.* It has an inside dimension of 0.098 inches, listed as their catalog number 889 at 20 cents each.)

In operation, solder is passed through the tube so as to just make itself known at the business end, this end being rested on the connection. Solder can be fed to the work with the thumb and forefinger, while some arrangement of the remaining three fingers is chosen to support the tube. Good stability will be promoted if the connection has a feature against which the inner edge of the tube can be braced. For example, I bend socket pins outward once they have passed through the board; I actually set the tube over the intended pin, at which point I lean the tube out to the side so as to permit the iron to reach the pin.

Once you are in position, find the lower half of the tube with the iron and slide it down onto the connection, all the while pressing the solder down against the work. I find this technique to be so easy that glee overtakes me, giving me a tendency to apply too much solder. Remember in using this technique that all the solder will be applied in the right place, for a change, and very little of it will be used up exploring the iron.

If left stationary in the tube after the connection is made, the solder will seize up in the bottom end. This is not due to actual bonding with the stainless steel, but is due to the flux solidifying, acting to glue the solder in place. Reheating the end of the tube with the iron will often loosen things up; otherwise your No. 55 drill can be used to ream the tube clear.

The way to prevent adhesion is to create relative motion between the tube and the solder while the flux is cooling. Some of us pull the tube away from the connection and run the solder through so as to protrude l/4 inch or so. Others withdraw the solder into the tube about l/2 inch or so. I spin the tube while it is cooling. All of this is done after the connection has been soldered; you have plenty of time because the flux must cool considerably before it solidifies.

Like anything, this takes a little practice; you will at first, by applying far too much solder or by heating up adjacent connections with the iron, inevitably bridge pins here and there. However, comparing my success with and without this instrument would be ludicrous--there is no comparison. Thanks to Mike, JA3TBW, there is a way to take the heat off our target practice when the going gets tough.

* Address List of Suppliers