Vectronics VEC-1500K User Manual download pdf (Page 10)

.050" 18

.040" 19

.031" 21

.025" 23

.020" 25

.015" 28

.010" 31

As you can see, there's a lot of them! However, most distributors carry only a

few of the more popular sizes. As a rule of thumb, solder manufacturers

recommend using the largest wire size with the highest flux percentage practical

to ensure good iron tinning and adequate flux delivery. In general, when solder

wire is too large for the job, you'll have difficulty controlling how much melted

solder is applied to the joint. When the wire is too small, you'll have difficulty

feeding enough solder onto the connection with a single well-controlled hand

movement.

In practice, many technicians like to keep a roll of .020-inch 63/37 for intricate

surface-mount work and a roll of .031 or .040-inch 60/40 for general bench use.

Large high-power component assembly require a thicker solder--.062-inch for

example--to provide rapid coverage of the joint area. Ultimately, the ideal wire

size depends on the task and on your personal preference.

Type of Core: In addition to the ten standard wire diameters, solders also come

in three core types--single core, multi-core, and solid core. Single-core solder

has one hollow cavity at its center filled with flux. Multi-core solder has several

smaller-diameter flux cavities clustered around the center. The manufacturers of

multi-core products claim better flux dispersion, but--in practice--both single and

multi-cores work acceptably well. Solid-core solder has no flux cavity. When

using solid-core solders, you must apply a flux paste to connections by hand

using a brush or syringe.

Single Core

Multi-Core

Solid

Size of Core: Not all flux cores are the same size. The core-size of wire solder

is especially important because it controls the amount of flux delivered to each

connection. Core size may be specified as a number (Kester No. 66), a generic

name ("regular"), or a flux percentage (3.3%). Flux percentage is based on the

weight of the flux as compared to the weight of 60/40 alloy. Three

"manufacturer's standard" core sizes are shown below:

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 67 68

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Vectronics VEC-1500K User Manual Page 10