Fatigue Resistant Solder Powder from
AMT, the World Leader in Solder Powders
MAXON POWER SOLDER is an important new key to improve reliability of electronic devices. The principal cause of structural failures in surface mounted solder joints is cyclic solder deformation. This deformation results from the mismatch of thermal expansions between joined parts during power cycles and ambient temperature changes. Both mechanical and thermal fatigue tests show that MAXON has up to seven times the fatigue resistance of traditional tin-lead eutectic solder.
MAXON offers superior fatigue resistance plus processability equal to the best traditional Sn-Pb solder available.
High speed production of advanced electronic assemblies requires that solder joints not only transmit electronic signals, but that they bear structural loads as well. MAXON offers you the important advantage of increased solder joint life, along with the ability to mount larger SM packages than ever before, using fine pitch and smaller solder loads.
MICROSTRUCTURAL INNOVATION
Mechanical tests of surface mounted leadless chip carrier joints
were conducted at room temperature under cycle in both tensile
and shear conditions. Thermal fatigue resistance was demonstrated
by MIL-STD thermal cycling joints lasted longer due to microstructural
refinement of the solder alloy.
In traditional Sn-Pb solder, excessive microstructural coarsening of a soldered joint is caused by inhomogeneous solder deformation during thermal cycling. Coarsening is the precursor to crack initiation, growth and the subsequential failure joint. The microstructural ratio of stability to strain distribution dictates the degree pf coarsening, which is a function of the uniformity fineness of particles in the structure. Refinement of MAXON's metallurgical microstructure substantially eliminates structural irregularities.
Unique dopant alloying has created a superplastic alloy with a uniformly fine and equiaxed grain. The dopants modify the constitutional supercooling during solidification. The resultant fine grain suppresses the coarsening kinetics of the solder under fatigue conditions.
The potential applications for MAXON are as broad as those for traditional Pb-Sn eutectic solder. Manufacturers of electronics who use MAXON, especially those who require high reliability or high densities in electronic systems will benefit through increased customer satisfaction, lower manufacturing costs and lower warranty returns cost.
Because MAXON's reflow temperatures and processing behavior effectively match those of traditional solders, your existing processing methods, equipment and conditions can be used without interrupting production.
TENSILE TESTING
Specimens of MAXON and traditional solder were fabricated for
testing under a cyclic sawtooth stress wave form at 0.001 Hz with
a peak tensile stress at 110% of the generic yield of Sn-Pb eutectic
solder. MAXON survived approximately seventeen times longer compared
to the number of cycles to failure for traditional solder.
SHEAR TESTING
Collar-pin torsion test speciments of cylindrical OFHC copper
rods joined by MAXON and traditional Sn-Pb solder were fabricated,
cleaned and measured for torsion fatigue testing. The cycling
frequency was 0.01 Hz and the plastic strain range per cycle applied
on the solder was approximately 10%. The average shear-failure
of MAXON was six times longer than the traditional Sn-Pb eutectic
solder.
THERMAL TESTING
Thermal fatigue resistance of MAXON was evaluated by thermal cycling
tests on surface mounted leadless chip carrier joints. Specimen
assemblies were fabricated for testing using MAXON and traditional
Sn-Pb solder pastes. The assemblies were tested under thermal
cycling conditions cited in MIL-STD. The integrity of all joints
was periodically examined under binocular stereoscope. The points
of joint failures were determined as functions of the number of
thermal cycles. Thermal fatigue resistance of MAXON joints was
five to seven times better than traditional solder.
Samples