Hafler DH-200 User Manual download pdf (Page 5)

A soldering “gun” is

not

recommended. The unfamiliar user is

more likely to damage the etched circuit boards with its higher

heat potential and unbalanced weight. Also, because he may

not wait long enough for it to reach operating temperature each

time it is switched on, poor solder connections are more likely.

Pencil irons are much lighter and easier to use, and there is no

waiting time when solder connections follow in sequence, as in

kit building. Make sure you have a holder for it, though, and

always unplug it when you take a break.

Proper Soldering

There are four steps to making a good solder connection:

Make a good mechanical connection to hold the wire in posi-

tion while heat and solder is applied.

Heat

thejunction

of the wire and lug, or hole, with the bright,

shiny top of the iron.

After heating for a couple seconds, apply solder to the junc-

tion. It should melt immediately and flow smoothly around

both surfaces.

Allow the connection to cool undisturbed.

Remember that the connection is made by the solder, not by

mechanically attaching the wire to the terminal. Usually the

wire is looped through the lug and crimped in place, but some

prefer to just place it through the hole and rely on the stiffness of

the wire to hold it while soldering. Connections to numbered

holes on the circuit board are handled this way.

Good solder connections are

essential

for trouble-free

noise-

free operation. A good solder joint does not require much solder

around the conductors. Never “butter” partially melted solder

on the joint, as it is useless. A good connection looks smooth and

bright because the solder flows into every crevice when the

parts are hot enough. The iron must have a bright, shiny tip to

transfer heat easily to the junction. That’s why the damp sponge

should be used frequently to wipe the tip, and occasionally you

must add a small amount of solder to the tip, too. If a connection

is difficult to heat, “wet” the tip with a small blob of solder to pro-

vide a bigger contact surface to the joint. Once the solder flows

around the conductors, any movement must be avoided for a

few seconds to allow a good bond. When cool, check the con-

nection by wiggling the wire. If in doubt, or if the connection is

not shiny, re-heat the joint. Excess solder may be removed from

a connection by heating it and allowing the solder to flow onto

the iron, which is then wiped on the sponge.

ALL SOLDER USED MUST BE ROSIN CORE.

Never use acid core solder or any separate flux in electronic

work. Silver solder is also not suitable. If in doubt about unmark-

ed solder, always obtain a fresh supply of rosin core solder. We

recommend 60/40 for easiest use. Do not confuse it with 40/60,

which is harder to melt.

The general procedure is to use a hot iron for a short time to

heat a connection, then add solder with the iron still in contact.

Remove the solder once it flows, and then remove the iron. A

cooler iron applied for a longer time is more likely to damage

components, or lift the copper circuit pattern from the boards. A

break in the etched circuit can be mended by simply soldering a

small piece of wire across it. Do not allow much build-up of

solder on the tip of the iron, or it may fall into adjacent circuitry.

When soldering to a numbered hole on the board, insert the

wire from the components side, and apply the iron, leaving

some bare wire exposed so that you can see that the hole is then

filled with solder for a secure bond. A round wooden toothpick

is suggested so that you can heat and clear the hole of solder if it

hinders your inserting the wire. Some builders prefer to clear

every hole first with a touch of the iron and toothpick. If the wire

has first been “tinned,” no additional solder may be necessary if

solder fills the hole, but it is good practice to push the wire

through, and then back it up a bit, to be sure solder fills the hole

from both sides. Make certain a bright, shiny flow is evident

from the wire, across the hole, onto the circuit pattern on the

board.

“Tinning” refers to the process of applying a light coating of

solder to the bared wire end. This keeps all the strands secured,

and also makes a good connection easier. Simply touch the wire

with the iron for a couple of seconds, and apply solder. Allow the

excess to flow away onto the iron. When properly done, the

wire is uniformly bright, and no larger than before. The hookup

wire supplied with this kit does not normally need tinning, for it

is pre-tinned.

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Hafler DH-200 User Manual Page 5

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