Elenco Solder Practice Kit w/ Iron & User Manual
Page 3
Introduction
Almost every electronic device today has a printed circuit board whether
you are assembling a PC board or repairing it, you must understand the
basics of working with these boards.
A poorly soldered joint can greatly affect small current flow in circuits and
can cause equipment failure.
You can damage a PC board or a
component with too much heat or cause a cold solder joint with
insufficient heat.
Sloppy soldering can cause bridges between two
adjacent foils preventing the circuit from functioning.
Good soldering requires practice and an understanding of soldering
principles.
This solder practice project will help you achieve good
soldering techniques, help you to become familiar with a variety of
electronic components, and provide you with dynamic results.
If the
circuit has been assembled and soldered properly, the LED will
alternately flash and the speaker will produce a wailing sound.
Solder
Solder is a fusible alloy composed of tin and lead. Some solder may
contain small amounts of other material for use in special purposes to
enhance its characteristics. Solder has a melting temperature around
360
O
to 370
O
, making it ideal for forming a metallic joint between two
metals.
Solder is identified by the ratio of tin-to-lead. The most common ratios
are 40/60, 50/50 and 60/40. Solder with a greater tin content melts at a
lower temperature, takes less time to harden, and generally makes it
easier to do a good soldering job. The ratio of tin is a main factor in the
strength of the solder joint. Solder with a greater tin content has a greater
holding ability under stress. Solder with a tin ratio of 60% is the strongest,
while solder with less than 30% would be undesirable.
Flux
Most solder contains flux in the hollow core of the solder allowing it to be
applied automatically when you heat the solder. The flux will remove any
oxide film on the metals soldered creating a good metal-to-metal contact.
This is called “wetting the metal”. There are three types of solder of solder
fluxes: chloride, organic and rosin. In the electronics industry, only the
rosin type is used. Rosin flux comes in two types, pure and active. The
most reliable is the pure type, since it doesn’t cause dendrites between
tracks on the PC board as the active type does.
Due to the highly
corrosive and moisture attracting characteristics of the chloride and
organic type fluxes, they should not be used in electronics.
-2-
-9-
Quiz
1.
Solder is comprised of what two materials?
A. gold and copper.
B. tin and lead.
C. zinc and copper.
D. lead and aluminum.
2.
What type of flux should be used in electronics?
A. chloride.
B. organic.
C. rosin.
D. corrosive.
3.
When working on PC boards, what wattage range of iron is ideal?
A. 15-40 watts.
B. 50-100 watts.
C. 1-10 watts.
D. 100-200 watts.
4.
Tinning the soldering tip will prevent it from
A. heating.
B. melting.
C. soldering.
D. oxidating.
5.
Proper solder adhesion requires that the metal surface to be
A. solder free.
B. clean.
C. greasy.
D. cold.
6.
Solder wick is used to
A. remove solder.
B. solder in small parts.
C. cleaning the soldering iron tip.
D. removing flux.
7.
A cold solder joint is caused by
A. a solder bridge.
B. using 60/40 solder.
C. insufficient heat.
D. acid core solder.