This PPT explains Wiring, testing and soldering electronic circuits

1. Wiring, Testing and Soldering
Electronic components
Dr.R.Hepzi Pramila Devamani
Assistant Professor of Physics
V.V.Vanniaperumal College for Women,
Virudhunagar

2. Introduction
• A circuit is any loop through which matter is carried.
• For an electronic circuit, the matter carried is the charge by electronics and
the source of these electrons is the positive terminal of the voltage source.
• When this charge flows from the positive terminal, through the loop, and
reaches the negative terminal, the circuit is said to be completed.
• However this circuit consists of several components that affect the flow of
charge in many ways.
• Some may provide a hindrance to the flow of charge, some simple store, or
dissipate the charge. Some require an external source of energy, some
supply energy.

3. Introduction
 There can be many reasons why we need to build a circuit.
 At times we may need to glow a lamp, run a motor, etc. All these devices-a
lamps, a motor, LED are what we call as loads.
 Each load requires a certain current or voltage to start its operation. This
voltage may be a constant DC voltage or an AC voltage.
 However, it is not possible to build a circuit just with a source and a load.
 We need a few more components that help in the proper flow of charge and
process the charge supplied by the source such that an appropriate amount of
charge flows to the load.

4. Electronic Circuit
•An electronic circuit is composed of individual
electronic components, such as resistors,
transistors, capacitors, inductors and diodes,
connected by conductive wires or traces through
which electric current can flow.
•They allow the designer to make quick changes
to the circuit during development.

5. Wiring
• The wires in a circuit carry the electric current to various
parts of an electrical or electronic system.
• Wiring means a circuit of wires for the distribution of
electricity.
• Copper is the preferred wiring for your home over aluminum
because of its ease of use and ability to effectively conduct
electricity.
• It is more stable, durable, and performs better than aluminum
wires. Copper is known to have better Conductivity than
Aluminium.

6. Soldering
• Soldering is a process used for joining metal parts to form a
mechanical or electrical bond.
• It typically uses a low melting point metal alloy (solder) which is
melted and applied to the metal parts to be joined and this bonds to the
metal parts and forms a connection when the solder solidifies.
• It is different to welding in that the parts being joined are not melted
and are usually not the same material as the solder.
• Soldering is a common practice for assembling electrical components
and wiring.

7. Soldering
• Soldering may be used to join wires or attached components to a
printed circuit board (PCB).
• Wires, component leads and tracks on circuit boards are mostly made
of copper.
• The copper is usually covered with a thin layer of tin to prevent
oxidization and to promote better bonding to other parts with solder.

8. Types of Solder
• There are different types of solder used for electrical work.
• They are broadly classified as tin/lead solders or lead free solders.
• Tin/lead solders have been used for many years because of their ease
of use however they have been phased out of commercial use due to
the harmful effects on humans and the environment.
• Tin/lead solder is still available and is used by “hobbyists” and other
non-commercial users as it is still easier to use than lead free types.
• When using tin/lead solder there are additional safety precautions that
must be observed.

9. Flux
• For electrical soldering both solder wire and solder paste contain flux.
• This helps to clean the surfaces being soldered and prevent oxidization of
the hot solder.
• The composition of the flux will vary depending on whether it is in a paste
or wire, leaded or unleaded solder.
• Solder wire usually contains a flux called “rosin”. Most fluxes will produce
fumes when the solder is heated and these fumes are likely harmful to your
health.
• For occasional soldering it may be sufficient to have a well-ventilated
workspace but for longer or repeated exposure a fume extractor should be
used.
• Solder flux can also cause solder to spatter and eye protection should be
worn when soldering.

10. Soldering Irons
• Soldering irons come in many varieties and sizes. Soldering irons may be electric, gas powered or
externally heated. Most common types are electric.
• Simple electric soldering irons have no controls and you simply plug them in and wait for them to
heat up.
• Their temperature is regulated by the power of the heating element and heat loss to the
environment.
• Some soldering irons have temperature controls which allow the user to set a desired operating
temperature for the soldering iron.
• This is useful if the soldering iron is being used for different types of solders which have different
melting points or if the soldering iron is being used for other purposes such as heating heatshrink.
• It also introduces a problem if the user does not set an appropriate temperature for the work, solder
can be overheated and decompose.
• Hotter is not better! A temperature of around 320 °C works well for 60/40 leaded solder. Some
temperature controlled soldering irons use interchangeable tips to change the temperature at which
they operate.

11. Desoldering
• If a part that has been soldered needs to be replaced it needs to be “de-soldered”.
• Depending on the part and type of joint it may be possible to simply re-melt the solder and remove
the part, or it may be necessary to remove the solder from the joint so the part can be freed.
• Some methods for removing solder are solder wick, solder sucker or de-soldering tool. Solder wick
is a copper braid which is applied to the joint and heated with a soldering iron.
• As the solder in the joint is melted it is drawn into the solder wick like a sponge and is removed
from the joint. A solder sucker is a spring loaded syringe or rubber bulb.
• The tip of the solder sucker is placed near the joint as the joint is melted by a soldering iron. When
the sucker is operated a vacuum is created which draws the molten solder from the joint into the
body of the sucker.
• A de-soldering tool is a type of soldering iron with a hollow tip and is connected to a pump or
vacuum source. The tip of the de-soldering tool is placed onto the joint, typically over a component
lead, and once the solder has melted the pump is operated to draw the molten solder away.

12. Steps involved in Soldering
• Step 1: Solder
• Feel free to try slightly thinner or thicker diameter solder, but it is
highly recommended that you stick with 60/40 rosin core solder.
• Step 2: Turn It On
• Before any soldering can be done, the soldering iron needs to be
turned on and heated to the desired temperature.
• If your soldering iron is not adjustable-temperature type, just let it heat
up for about five minutes before trying to use it.

13. Steps involved in Soldering
• Step 3: Picking It Up
• Always pick up the soldering iron by the insulated handle! This cannot be
stressed enough... Always pick up the soldering iron by the insulated
handle!
• The metal part of the soldering iron is extremely hot and accidentally
gripping it will result in terrible burns.
• Step 4: Putting It Down
• Always put the soldering iron back onto the soldering iron stand when you
are done using it.
• An unattended soldering iron that has not been properly put away can be
disastrous, so it is extremely important that you always do this.

14. Steps involved in Soldering
• Step 5: Tin the Tip
• For a new soldering iron, you will want to melt a thin coat of solder
onto the tip. This is considered "tinning the tip."
• This thin coat will help to provide a base of solder which will help the
solder to flow when you actually try to solder things later.
• Step 6: Strip Wires
• All of the soldering for Simple Bots involves soldering wires together.
• The first step of doing this is to strip an inch of insulation away from
each of the wires you are trying to connect together.

15. Steps involved in Soldering
• Step 7: Twist
• Twist the exposed metal of the two wires together.
• Step 8: Solder
• Place the soldering iron to the wire joint, as to heat it up.
• Push the solder into the wire until it melts and they fuse
together.
• As soon as they appear to be fused, remove the solder and
iron.

16. Steps involved in Soldering
• Step 9: Trim
• Trim away any excess exposed wire.
• You only need the base of the solder joint where the two wires are
fused.
• Step 10: Clean
• After soldering anything, the tip of the soldering iron needs to be
cleaned off.
• To do this, simply wipe the tip over a special soldering iron cleaning
pad. Should you not have one, a mildly damp sponge works miracles.

17. Advantages and disadvantages of soldering
• This can be operated at low temperature.
• Base metal does not melt.
• Any metals, non-metals can be joined by this process.
• This operation required low power.
• Less time required to join.
• This can be easily operated.

18. Soldering Safety
• Never touch the element of the soldering iron.... 400°C!
• Hold wires to be heated with tweezers or clamps.
• Keep the cleaning sponge wet during use.
• Always return the soldering iron to its stand when not in use. Never
put it down on the workbench.
• Turn unit off and unplug when not in use.

19. Electronic Circuit Test Equipment
• Using the right testing equipment is vital when it comes to testing electronic
components and circuit boards.
• Testing confirms that an electronic equipment or product has been
manufactured correctly and therefore, if the design and assembling are okay,
it should do what it’s supposed to do.
• Following proper testing procedures for electronic circuits ensures that you
produce high-quality products that meet your customer’s requirements.
• One of the main uses for multimeters whether they are analogue
multimeters or digital multimeters, DMMs is to test and fault find circuits
like those in a transistor radio.
• Multimeters are ideal items of test equipment for finding many faults in a
transistor or other form of electronic circuit.

20. Testing with a Digital Multimeter
• To test a circuit board for a short circuit, you need to check the
resistance between different points in the circuit.
• If visual inspection doesn’t reveal any clues as to the location or cause
of the short circuit, grab a multimeter and try to track down the
physical location on the printed circuit board.
• You’ll need a very good multimeter with milliohm sensitivity, and it’s
easiest if it has a buzz function to alert you when you’re probing a
short.
• As an example, if you measure the resistance between neighboring
traces or pads on a PCB, you should measure high resistance.

21. Testing with a Digital Multimeter
• If you measure a very low resistance between two conductors that
should be in separate circuits, it is possible that these two conductors
are bridged, either internally or externally.
• Note that adjacent two traces or pads that are bridged with an inductor
(such as in an impedance matching network or a discrete filter circuit)
will produce a very low resistance reading as an inductor is just a
coiled conductor.
• However, if two conductors are very far apart on the board, and you
read very small resistance, then you have a bridge somewhere in the
board.

22. Testing Relative to Ground
• Set one probe on a ground connection, and touch the other probe throughout
other conductors on the board.
• This same ground connection will be present on other locations on the
board, meaning if you touch each probe to two different grounded vias, you
will read very small resistance.
• Pay attention to your layout while you do this as you do not want to
mistake a short circuit for a common ground connection.
• All other exposed conductors that are not tied to ground should read very
high resistance between your common ground connection and the conductor
itself.
• If you read a very low value, and you do not have an inductor between the
conductor in question and ground, then you may have a bad component or a
short circuit.

23. Shorted Components
• Checking for a shorted component also involves using a multimeter to
measure the resistance.
• In the case where visual inspection did not reveal excessive solder or
metallic flakes between pads, your short may have formed in the internal
layers between two pads/pins on a component.
• It is also possible that a short occurs between pads/pins on a component
due to poor fabrication.
• Here, you’ll want to measure the resistance between pins on an IC or
connector. Neighboring pins are particularly susceptible to shorts, but these
are not the only locations where a short can form.
• Check that your resistance between pads/pins with respect to each other
and the ground connection has low resistance.

24. Narrow Down the Location
• If you think you have located a short between two conductors, or between
some conductor and ground, you can narrow down the location by checking
nearby conductors.
• With one lead of the multimeter on the suspect shorted connection, move
the other lead to different nearby ground connections and check the
resistance.
• As you move to farther ground connections, you should see the resistance
change. If the resistance increases, then you are moving your grounded lead
away from the location of the short.
• This helps you narrow down the exact location of the short, and you can
even narrow it down to a specific pair of pads/pins on a component.

25. THANK YOU