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

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

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

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

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

Soldering Tools & Materials and their Uses (A)

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

Soldering Tools & Materials and their Uses (B)

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.)

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.)

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

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

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

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

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

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

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

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

Types of Poor Solder Connections and causes

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

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

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

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