1. Soldering & Circuit Fabrication
Basic Electronics- DC
Soldering & Circuit Fabrication
Trade & Industrial Education

2. Presentation Overview
Terms and Definitions
Soldering Tools & Materials and their Uses
Cleaning Before & After Soldering
Stripping and Tinning
Soldering Procedure
Characteristics of a Good Solder Connection
Types of Poor Solder Connections & Causes
Types of Soldered Connections
Safety rules protect you and those around you from injury.
Whose responsibility is safety and health in the classroom laboratory? (Students’, teachers’, everyone’s)
Trade & Industrial Education

3. Terms and Definitions
Oxides- Films and impurities which form on the surface of metals when exposed to air or water and which , if not cleaned off, will prevent a good bond between the surfaces and solder
Rosin- A material obtained from pine trees which is used during soldering to help ensure a good bond between the solder and the solder and the metal surfaces
Wetting- The ability of molten solder to flow over and fuse completely with the metal surfaces to which it is applied (NOTE: Dirt, grease, and oxides prevent good wetting during soldering.)
Stripping- Removing insulation from electrical conductors

4. Terms and Definitions (cont’d)
Tinning- The application of a small amount of solder to surfaces to be soldered to help ensure good wetting during soldering
Flux- A liquid or solid which when heated cleans and protects surfaces to be soldered
Crimping- Applying mechanical pressure to compress a sleeve-type or cup-type electrical terminal to ensure a good electrical connection between the sleeve and the conducting wires it contains
Land- Printed wiring attached to the surface of a printed circuit boards

5. Soldering Tools & Materials and their Uses (A)
Soldering Iron, 100 watt- For soldering large electrical connections
Soldering Pencil, 10 to 35 watt- For soldering small electrical connections
Soldering Gun, 100 watts- For soldering large electrical connections where better heat control is required
Resistance Soldering Unit- For soldering many connections in close spaces
Adjustable Power Source- For controlling soldering iron tip temperature (NOTE: Variac is a commonly used adjustable power source.)
Soldering iron stand- For supporting a hot soldering iron when not in use
Heat sink- For drawing heat from soldered connection to prevent damage ot components
Mechanical wire strippers- For cutting and pulling insulation from ends of connectors
Thermal wire strippers- For removing wire insulation by heating and melting the material; prevents removing wire strands, but cannot be used on insulation that will not melt, such as glass braid or asbestos
Crimping Tool- For making a strong mechanical connection to certain sleeve-type terminals
Nail Nippers- For use in clipping component leads flush with surface

6. Soldering Tools & Materials and their Uses (A)

7. Soldering Tools & Materials and their Uses (B)
Component lead cleaner- For removing oxides and other films from component leads
Typewriter eraser- For removing oxides and other films from terminals to be soldered
Isopropyl Alcohol- For removing oil, grease, and flux from conductors and terminals both before and after soldering
Solder- For making electrical connections; most common type is 60/40 rosin-core solder containing 60% tin and 40% lead, with a center core of rosin flux to allow simultaneous application of both solder and flux
Long nose and Needle nose pliers- For making mechanical connection prior to soldering; may also be used as heat sink during soldering
Diagonal cutting pliers- For cutting conductors
Flux- For ensuring a good electrical connection by cleaning and wetting all surfaces during soldering; not required if the solder contains a rosin core
Solder sucker- For removing melted solder from a terminal to be re=soldered (NOTE: There are many different brands available including Soldawick and Soldavac, etc.)
Spaghetti-sleeve insulation- For preventing electrical connections from becoming shorted to adjacent connections
Heat-shrink insulation- Sleeve-type insulation which, when heated, shrinks to form a snug fit over a soldered connection

8. Soldering Tools & Materials and their Uses (B)

9. Cleaning before and after soldering
(CAUTION: Use safety goggles or glasses when soldering)
Oil, grease, and dirt- Wipe with isopropyl alcohol and clean cloth
Old Solder- Heat with soldering iron, and wick away, or suck up by means of a solder sucker
Oxides
1. Component leads- Use component lead cleaner
Terminals- Use typewriter eraser
Rosin flux- Wipe or brush with isopropyl alcohol or flux cleaner
(CAUTION: Use alcohol only in well-ventilated spaces and do not permit open flames in the vicinity.)

10. Stripping and Tinning
Make clean cut at wire end by cutting off small length with diagonal cutting pliers
Lay wire in proper size slot of wire strippers and strip approximately one inch of insulation from wire end (CAUTION: If too small a slot in wire strippers is used for stripping, the strippers will cut off some of the wire strands. This could result in an electrical connection of higher resistance than desirable.)

11. Stripping and Tinning (cont’d)
Care must be taken not to remove wire strands when stripping
If wire strands have been separated, gently re-twist wire in same direction as original twist
After stripping, clean the wire strands with isopropyl alcohol and paper towel
Place heat sink on wire strands immediately adjacent to wire insulation before tinning
Tin soldering iron tip as follows:
Wrap a piece of solder around tip three or four times
Plug in unit and allow it to heat up, adjust variac to point just past where solder melted
Wipe tin with moist paper towel or wet sponge
As soon as tip will melt solder, coat tip with solder; wipe off excess
If rosin-core solder will not be used, wipe small amount of liquid or paste rosin flux on bare strands of stripped wire
Set hot soldering iron in holder or vise

12. Stripping and Tinning (cont’d)
Melt small bead of solder on iron tip and slowly draw bare wire through solder bead from heat sink toward wire end; apply additional solder as needed (CAUTION: After the wire has been tinned, the outline of the wire strands should be visible. If they are not, too much solder has been applied. Reheat wire and wipe off excess solder. If some strands are still loose, too little solder has been applied. Reheat wire and apply additional solder.)
Remove heat sink from tinned wire
After solder has cooled, clean the tinned wire with isopropyl alcohol and paper towel or clean cloth

13. Soldering Procedure Clean all surfaces to be soldered
Strip and tin wires to be soldered
If electrical connection is to be insulated, slide approximately one-inch length of spaghetti insulation onto the tinned wire
If possible, mechanically connect tinned wire to terminal or lug bt means of long nose or needle nose pliers, make sure distance between terminal and wire insulation is no more than 1/32 to 1/8 inch, depending on wire gauge

14. Soldering Procedure continued
If mechanical connection is not possible, make sure component to be soldered is held stationary in vise or clamp to prevent movement during soldering
Select proper soldering iron for the job, depending on:
Size of connection
Heat sensitivity of components
Proximity of other connections and wires
Heat and tin the soldering iron
Attach heat sink as close as possible to connection without interfering with soldering operation

15. Soldering Procedure continued
If rosin-core solder is not to be used, brush small amount of rosin flux on terminal
While making sure that no part of the connection moves, apply hot iron tip to terminal and wire, and apply solder to wire, component, or terminal lead; remove iron tip and solder as soon as solder has flowed freely over, around, and through the connection
After solder has cooled, clean connection with isopropyl alcohol
If connection is to be insulated, slide spaghetti sleeving over connection
If applicable, remove component from vise or clamp

16. Characteristics of a Good Solder Connection
Slivery, shiny appearance to solder surface
Good wetting of solder to surfaces
Solder completely covers connection, but contour of connection is still visible

17. Characteristics of a Good Solder Connection
Insulation
No burnt areas
No damaged insulation
Gap between insulation and connection is approximately the diameter of the wire insulation
No spilled solder
No pits or holes in the solder surface

18. Types of Poor Solder Connections and causes
Cold solder joint- Insufficient heat
Disturbed joint- Connection moved before solder solidified
Excessive solder- Too much solder applied
Insufficient solder- Too little solder applied
Dewetted solder joint- Insufficient cleaning or insufficient use of flux
Burnt insulation- Excessive heat or carelessness with iron
Insulation damage- Excessive heat applied, excessive iron application time, or lack of heat sink
Rosin solder joint- Excessive rosin or insufficient heat
Solder short- Excessive solder or carelessness

19. Types of Poor Solder Connections and causes

20. Types of soldered connections A
Types of soldered connections A. No mechanical connection prior to soldering

21. Types of soldered connections B
Types of soldered connections B. Partial mechanical connection prior to soldering

22. Types of soldered connections C
Types of soldered connections C. Full mechanical connection prior to soldering

23. Presentation Summary Terms and Definitions
Soldering Tools & Materials and their Uses
Cleaning Before & After Soldering
Stripping and Tinning
Soldering Procedure
Characteristics of a Good Solder Connection
Types of Poor Solder Connections & Causes
Types of Soldered Connections