Soldering Technology Using Lasers
Laser soldering is a technique in which a 30–80 W laser is used to
melt and solder an electrical connection joint. Diode laser systems
based on semiconductor junctions are used for this purpose.
Wavelengths are typically 808 nm to 980 nm. The laser beam is
delivered to the workpiece through the fiber optic cable of 200 –
800 ㎛ diameter. The rapidly spread laser beam at the end of the
fiber cable can be adjusted into a specific form with a certain focal
length using an optical head consisting of lenses. If a wire solder is
used, it requires a separate wire feeder. If a cream or paste type
solder is used, a device to apply the solder in the previous process
Mixtures of lead-tin, silver-tin, and copper-tin can be used for
soldering. Different soldering methods can be used depending on
the properties of the different alloy materials. If the laser power or
the exposure time is not sufficient, bonding between the solder wire
and the material can be degraded or a blow hole can be generated.
This causes a weakening of the bonding strength of the soldering
Soldering is a process in which two or more items are joined
together by melting and putting a filler material (filler metal having a
lower melting point than the adjoining metal) into the joint.
Soldering differs from welding in that soldering does not involve
melting the workpieces. In brazing, the filler metal melts at a higher
temperature, but the workpiece metal does not melt. In the past,
nearly all solders contained lead, but environmental and health
concerns have increasingly dictated the use of lead-free alloys for
electronics and plumbing purposes. Laser soldering is suitable for
terminal bonding of electronic circuits, local soldering for PCB
repairs, and narrow-space soldering inaccessible to soldering tips.
The beam size of the laser is available from 200㎛ to several ㎜, and
takes between 0.6 and 1.0 seconds per point.
Applications of Laser Soldering
[Application cases of laser soldering]