SOME USEFUL TIPS TO GOOD SOLDERING

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