Vectronics VEC-1500K User Manual
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Some manufacturers offer special variations such as the "bent conical tip" or
"micropoint tip" for special applications. Also, for slightly better heat transfer,
some narrow screwdriver tips may be used interchangeably with the longer
conical tips.
Tip Construction:
Most iron tips are made from copper, a metal with unusually
good thermal storage and heat transfer characteristics. Although great for
storing heat, copper is quite soft and oxidizes rapidly when exposed to air. If
used "as is", copper tips erode quickly and require continual maintenance. To
prevent this, manufacturers electroplate them with one or more protective layers
to add toughness and extend life.
One popular tip-plating scheme is illustrated in the following diagram. The
outer layer of the shank is electroplated with chrome, a non-solderable metal.
Chrome is applied to prevent solder from wetting and sticking to the back
portion of the tip. This reduces the need for cleaning, and prevents the shank
from becoming stuck in the iron barrel due to a buildup of solder deposits. A
layer of nickel plating beneath the chrome outer-surface prevents corrosion and
"pitting" as the tip ages. The inner-most layer of electroplate is iron, and this
covers the entire tip. Iron helps harden the shank, and it prevents solder from
combining directly with the softer copper core beneath the tip's contact area.
Note that the contact area is tinned with solder. Maintaining this surface is an
important part of tip maintenance and care. Without complete wetting of the
contact area, heat transfer would be extremely difficult--and the iron would fail
to perform!
Copper Core
Nickel electroplating
Chrome electroplating prevents wetting
Iron barrier prevents
dipped in 63/37 solder
Working part of tip
prevents corrosion
solder from combining
with copper core
The exact composition and layering of a tip's outer shell may vary from
manufacturer to manufacturer, but most high-quality tips have multiple layers of
electroplating to ensure long life and top performance.