Soldering Basics

1
Soldering Basics
2
Overview

• Introduction
• Definition
• Equipment
• Procedure
• Preparation
• Execution
• Finishing
• Specific Techniques
• Desoldering
• Tinning
• Conclusion
• References

3
Introduction Definition

• Unite two base metal items
• Add filler metal (solder)
• Typ. lt 842F (450C) melting point
• Metal flows via capillary action
• Metal bonds via wetting action
• Metallurgical joint exhibits
• Fair mechanical strength
• Excellent electrical conductivity
• Watertightness

4
Introduction Common Usage

• Electronics
• Plumbing
• Stained glasswork
• Jewelry
• Orthodontics

5
Introduction Equipment

• Solder
• Joint filler metal
• Metallic alloy
• Sn/Pb
• Typ. 60/40 or 63/37 mix
• 60/40 melts _at_ 374F (190C)
• 60/40 melts _at_ 364F (183C)
• Pb-free
• EU RoHS compliance
• Typ. Sn/Ag/Cu alloy
• Melts _at_ 422433F (217223C)

6
Introduction Equipment

• Flux
• Removes base, filler metal oxides
• Aids wetting process
• Rosin-based flux
• Availability
• Separate paste
• Flux-in-core solder
• Primary fume component

7
Introduction Equipment

• Soldering Iron
• Solder melting heat source
• Power rating
• Higher power ? higher tip temp
• Higher power ? heat larger joints
• 15-35W for electronic work
• Various tips available
• Conical, chisel types
• Tip width 70-90 contact width
• Never use cold heat irons on electronics!

8
Introduction Equipment

• Solder wick
• Braided copper strands
• Flux impregnated
• Absorbs solder when heated
• Remove excess solder
• Desolder components
• Solder stand sponge
• Always return iron when unused
• Always clean tip
• Remove burnt flux
• Remove excess solder

9
Introduction Equipment

• Heat sink
• Protect heat sensitive components
• Clip between component body and iron
• Substitution
• alligator clips
• Hemostat
• 99 alcohol brush
• Clean joint residual flux
• Purity important

10
Procedure Preparation

• Clean components
• Remove dirt, grease, oxidation
• Causes unwettability
• Solder tend to bead up
• Component leads bright, shiny
• Solder pads bright copper color
• Fine steel wool, emery cloth

11
Procedure Preparation

• Prepare iron
• Plug in iron
• Dampen sponge
• Clean tip w/ sponge
• Apply solder to iron tip (tinning)
• Wipe excess solder
• Tip should be have silvery sheen

12
Procedure Execution

• Place component
• Bend leads to fit hole pattern
• Insert component through correct holes
• Clinch leads slightly outward to hold in place
• Attach heat sink if needed

13
Procedure Execution

• Solder component
• Wipe iron w/ sponge
• Apply tiny solder amount to iron tip
• Not solder to form joint
• Helps conduct heat properly
• Touch tip side to BOTH pad and lead
• Add bit more solder to form heat bridge
• Wait for joint to be heated (1-2 sec)

14
Procedure Execution

• Solder component (cont.)
• Feed small solder amount from opposite side
• Molten solder should spread and fill joint
• Move solder away first
• Move iron away quickly
• Return iron to stand
• Entire process 5 sec
• Wait additional 3-5 sec for joint cooling

15
Procedure Inspection

• Inspect joint quality
• Good joint
• Shiny
• Bright
• Smooth
• Concave solder fillet
• Good wetting

16
Procedure Inspection

• Inspect joint quality (cont.)
• Bad joints
• Balled up or spiked
• Dull color
• Crystalline or grainy looking
• Convex solder fillet
• Dewetted
• Causes
• Dirty leads, pads
• Movement during cooling
• Overheating

17
Procedure Finishing

• Return iron to stand
• Cut excess lead length
• Clean residual flux w/ alcohol
• Prevent future oxidation
• Prevent unwanted electrical shorts

18
Techniques - Desoldering

• Repair bad joints
• Remove solder bridges
• Excess solder connects two pads, leads
• Unwanted electrical connection formed
• Remove components
• Both require old solder removal
• Place solder wick against solder joint
• Heat wick opposite side from joint
• Solder should wick up braid
• Remove braid first
• Remove and return iron to stand

19
Techniques Wire Tinning

• Must tin wires before soldering to components,
  board
• Attach heat sink just below insulation
• Heat wire end
• Touch solder to wire opposite iron tip
• Solder should wick up wire
• Too much heat damages wire insulation

20
Conclusion

• Introduction
• Definition
• Equipment
• Procedure
• Preparation
• Execution
• Finishing
• Specific Techniques
• Desoldering
• Tinning

21
References

• www.curiousinventor.com/guides/How_To_Solder
• www.aaroncake.net/electronics/solder.htm
• www.qsl.net/n9zia/solder.html
• www.solderinguide.com
• itp.nyu.edu/physcomp/Tutorials/SolderingAPerfBoard
  
• www.modchipworld.co.uk
• www.drmsmetals.com/data/electronic/erzin.html
• www.hsl.gov.uk/capabilities/rosin.htm
• www.sparkfun.com
• www.howardelectronics.com
• www.ladyada.net
• www.uelectronics.info
• us.geocities.com/steves_workshop
• www.theavenuestaineglass.com