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THE IMPORTANCE OF CORRECT SOLDERING IRON TEMPERATURE APPLYING THE CORRECT
TEMPERATURE TO SOLDER JOINTS CAN MAKE THE DIFFERENCE BETWEEN HAVING A
SOLIDLY CONSTRUCTED PROJECT IN HAND OR A DISASTER.  IN GENERAL, LEAD BASED
SOLDER USUALLY CALLED 60/40 BECAUSE IT IS 60 TIN AND 40 LEAD REQUIRES A TIP
TEMPERATURE OF 460 F, AND LEAD FREE SOLDER REQUIRES ABOUT 100 DEGREES
HIGHER.  THE COMPOSITION OF LEAD FREE SOLDER IS ROUGHLY 99 TIN, 0R7 COPPER,
PLUS VARIOUS TRACE METALS.  THE TEMPERATURE CONTROLLED SOLDERING IRONS IN
THIS REVIEW ARE CAPABLE OF PRODUCING TIP TEMPERATURES OVER 800 F, SO PROPER
TEMPERATURE ADJUSTMENT IS NEEDED.  THERE ARE TWO COMMON PROBLEMS WITH
INCORRECTLY CONTROLLED SOLDERING IRON TEMPERATURE.  FIRST, AS SEEN IN
FIGURE E, AN INEXPENSIVE, POORLY MADE PRINTED CIRCUIT BOARD PCB CAN
LITERALLY BE BURNED AND ITS COPPER TRACES AND PADS LIFTED UP OR EVEN
DESTROYED.  THE BURN MARK SHOWN IN THE PHOTO IS DUE PRIMARILY TO A POOR
QUALITY PCB AND A TIP TEMPERATURE SET FOR LEAD FREE SOLDER.  BEFORE WE LOOK
AT THE OTHER COMMON PROBLEM, LETS EXAMINE A GOOD SOLDER JOINT IN FIGURE F.
THOSE COLORS YOU SEE ARE NOT ACTUALLY IN THE JOINT A GOOD SOLDER JOINT IS
SHINY, SO WHAT YOU SEE IN THE PHOTOGRAPH IS A REFLECTION OF THE MICROSCOPE
AND MICROSCOPE LIGHT USED TO CAPTURE THE PICTURE.  AT THE PROPER
TEMPERATURE, SOLDER WILL FLOW EASILY ON THE WIRES AND SURFACES AND WILL
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