Soldering 101

A Really HOT Topic

Soldering

• The process of making an electrical connection by melting low-temperature metal alloys around component leads
• Soldering is just as much an “Art” as it is a “Science”
• We will:
• Go over some soldering vocabulary
• Illustrate graphically soldering techniques
• Solder a few components on the TV Remote board
• Complete the board as homework

Soldering Process in Brief

1. Turn on soldering iron and let it get to temperature
2. Clean soldering tip with a damp cloth or sponge
3. Install the component and hold in place with a physical connection
4. Heat the component lead and the adjacent circuit board pad – apply the right amount of heat (art)
5. Touch solder to the component lead and pad - melt the right amount of solder (art)
6. Remove solder
7. Remove heat (art)
8. Hold steady until cool
9. Inspect the connection (art and good eye)

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Vocabulary

• Circuit Board
• PCB (printed circuit board)
• Components

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Vocabulary

• Component side
• IC socket
• Pins

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Vocabulary

• Point-to-Point wiring
• Component leads

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Vocabulary

• Tinning
• Wetting
• Flow
• Pad - connection

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Vocabulary

• Connection
• Volcano
• Shine or sheen
• Dull or crusty
• Cold solder joint
• Tack-solder

Vocabulary

• Soldering Iron
• Tip
• Soldering Station
• Tip cleaning surface

Solder Types

• Rosin core and Flux
• Flux type is used for household soldering
• Rosin core is used for electrical wiring (reduced corrosion potential)
• Rosin and flux are chemical compounds that clean the metal surfaces that are being soldered
• The rosin or flux melts first to contact the joint
• The rosin or flux float the impurities away from the metal surfaces and to the top surface of the solder joint
• Produces the smoke you will see associated with soldering
• You will be using rosin core solder

Rosin Core Solder

• Outer tube of low melting alloy
• Tin
• Lead
• (Industry is moving toward lead-free)
• Silver
• Copper
• Other specialized metals
• Inner core is the rosin

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Soldering Process in Brief (again)

1. Turn on soldering iron and let it get to temperature
2. Clean soldering tip with a damp cloth or sponge
3. Install the component and hold in place with a physical connection
4. Heat the component lead and the adjacent circuit board pad – apply the right amount of heat (art)
5. Touch solder to the component lead and pad - melt the right amount of solder (art)
6. Remove solder
7. Remove heat (art)
8. Hold steady until cool
9. Inspect the connection (art and good eye)

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Soldering Process

• Insert component from the “component side” of the PCB and bend leads out to physically hold the component steady and in place
• When you can’t bend leads – “Tack Solder” one lead to hold component in place

Soldering Process

• Touch the tip to the component lead AND the pad
• Apply just enough heat
• TLAR (That Looks About Right)

Soldering Process

Soldering Process

• When you have headed the joint just the right amount (TLAR) touch solder to lead and pad (not to the tip)
• Do as I say, not as I do!
• Why I sometimes will use the tip?

Soldering Process

• The melting solder will flow around the joint
• Called wetting
• Surface tension will produce a nice “Volcano” looking joint
• Keep the tip in place until TLAR

Soldering Process

• Remove solder then tip and allow joint to cool
• Hold steady while cooling
• Inspect for good joint (TLAR)
• Reheat “cold solder” joints
• Clip and remove excess leads (safety first, watch for flying leads)

Good vs. Bad Solder Joints

• Cold solder joints are probably the cause of most circuit problems!
• You need to use caution not to overheat a joint (TLAR)
• But don’t get overly concerned except for the most delicate components

Some Safety Concerns

• Don’t solder while circuit is powered
• Use well ventilated and lighted work space
• Don’t touch the solder tip – it’s hot
• Static discharge protection – not a hazard for you but can trash some sensitive components
• Watch for flying leads when clipping excess