SOME USEFUL TIPS TO GOOD SOLDERING
SOME USEFUL TIPS TO GOOD SOLDERING
1. The
two surfaces to be soldered should be thoroughly cleaned and made free from any
dust, grease or oil. Infact, thorough cleaning of the PCB before beginning the
soldering operation and proper tinning of the component leads at the time of
soldering that Component achieves good results.
2. A
small quantity of flux may be applied on the surfaces to be soldered. It is the
function of the soldering flux to keep away any oxide film during soldering
operation and allow the two surfaces to make a metallic contact and alloy with
each other. The flux residue should be removed after the soldering is done.
3. One
of the most common problems in soldering is the application of insufficient
heat. The alloying action in soldering cannot be achieved without a uniform
distribution of heat between the solder and the metal being soldered. If hot
solder is applied to a cold metal or a cold solder is applied to a hot metal,
there can never be a proper soldering action. Soldering will be proper only when
the solder alloy is hot enough to remain in a liquid state as soldering is
being done. To achieve a proper wetted soldered joint, heat up the component
terminal end slightly (Remember not to exceed the component lead temperature
beyond the safe recommended temperature. Excessive temperature can often damage
sensitive semiconductor devices) and apply solder alloy right onto the
component lead end instead of applying it on the soldering iron tip. Now with
the soldering iron tip, melt the solder so that it flows over the joint. Avoid
putting excessive solder metal and ensure that it is in the liquid state till
it has completely flowed over the joint. A perfect soldered joint would give a
shiny bead like appearance.
SOLDERING TEMPERATURES FOR DIFFERENT COMPONENTS
Table lists the typical values of recommended soldering
temperatures for different electronic components and devices.
Sl no
|
Type of Electronic component
|
Soldering Temperature
|
Soldering Time
|
1
|
General
Purpose fixed and variable Resistor
|
3500C
|
5 seconds
|
2
|
Light
Dependent Resistors, Varistors, thermistors
|
2500C
|
-
|
3
|
Electrolytic
Capacitor
|
2250C
|
5 seconds
|
4
|
Other
Capacitor types
|
2000C
|
Less than 5 seconds
|
5
|
Silicone
Diodes
|
2500C
|
5 seconds
|
6
|
Germanium
Diodes
|
2000C
|
5 seconds
|
7
|
Low
Wattage Zener Diodes
|
2000C
|
10 seconds
|
8
|
Light
Emitting Diode
|
1500C
|
10 seconds
|
9
|
Power
Transistors (in TO-3 and TO-66 package)
|
2750C to 3000C
|
5 seconds
|
10
|
Transistors(TO-39,
TO-5 package)
|
2250C
|
5 seconds
|
11
|
Transistor(TO-220AB
package)
|
2500C
|
5 seconds
|
12
|
Small
signal transistors (in TO-92 plastic, TO-72, TO-18, SOT-25 package), FETs,
MOSFETs
|
1500C to 2000C
|
-
|
13
|
General
purpose linear ICs like Opamps, Timers, IC Voltage Regulators, PLLs etc.
|
2500C
|
5 seconds
|
14
|
TTL
ICs
|
1750C
|
10 seconds
|
15
|
CMOS
ICs
|
2000C to 2400C
|
5 seconds
|
