Fraunhofer Institute for Ceramic Technologies and Systems IKTS
Fraunhofer Institute for Ceramic Technologies and Systems IKTS

Measurement of viscoplastic properties

Topic

Various electro-mechanical testers and test sequences are used to determine mechanical material parameters of the elastic, plastic and viscoplastic deformation behavior of materials used in assembly and connection technology (AVT) (see examples). The aim is to provide mathematically described stress-strain behavior as well as the softening behavior as a function of temperature and time. The mathematical models then are applied for the boundary conditions occurring in the laboratory and field under which the electronics or micromechanical system is to be designed.

  • Examples
  • Solder alloys
  • Solder contacts
  • Silver (Ag) sintered contacts
  • Copper (Cu) sintered contacts
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Isothermal tensile test with constant controlled deformation rate to determine the elastic and plastic deformation behavior (left: Strain versus time, center: mechanical stress versus time, right: mechanical stress versus strain).
© Fraunhofer IKTS
Isothermal tensile test with constant controlled deformation rate to determine the elastic and plastic deformation behavior (left: Strain versus time, center: mechanical stress versus time, right: mechanical stress versus strain).
Isothermal creep test to determine creep rates (left: constant mechanical stress versus time, center: Strain versus time, right: strain rate versus strain).
© Fraunhofer IKTS
Isothermal creep test to determine creep rates (left: constant mechanical stress versus time, center: Strain versus time, right: strain rate versus strain).
Isothermal cyclic fatigue test to determine the softening behavior at constant strain rate and strain amplitude (left: max. stress versus cycles, center: range of variation of mechanical stress versus accumulated strain, right: accumulated strain at 50% of softening for two strain amplitudes).
© Fraunhofer IKTS
Isothermal cyclic fatigue test to determine the softening behavior at constant strain rate and strain amplitude (left: max. stress versus cycles, center: range of variation of mechanical stress versus accumulated strain, right: accumulated strain at 50% of softening for two strain amplitudes).
Isothermal test sequence for determining material parameters for the unified model describing elastic, plastic and viscoplastic deformation behavior (left: Strain versus time with three strain amplitudes and four strain rates, center: stress versus time, right: mechanical stress versus strain).
© Fraunhofer IKTS
Isothermal test sequence for determining material parameters for the unified model describing elastic, plastic and viscoplastic deformation behavior (left: Strain versus time with three strain amplitudes and four strain rates, center: stress versus time, right: mechanical stress versus strain).

Electro-mechanical tension-compression tester for bulk materials

© Fraunhofer IKTS

Characteristics

  • Temperature range: 25 °C to 150 °C
  • Force range: ± 1000 N
  • Force accuracy: ± 100 mN
  • Displacement range: < 2500 µm (inductive, optical)
  • Displacement accuracy: ± 25 nm

Test types

  • Force-constant tests (creep tests, creep tests)
  • Velocity and strain rate controlled tests
  • Relaxation tests
  • Cyclic fatigue tests
  • Combined test sequences

Materials

  • Brazing alloys
  • Metals
  • Polymers

Electro-mechanical LabShear tester for electronic connections

© Fraunhofer IKTS

Characteristics

  • Temperature range: 30 °C to 400 °C
  • Force range: ± 20 N, ± 500 N
  • Force accuracy: ± 10 N, ± 100 N
  • Displacement range: < 2000 µm (capacitive, optical)
  • Displacement accuracy: ± 10 nm

Test types

  • Force-constant tests (creep tests, creep tests)
  • Velocity and strain rate controlled tests
  • Relaxation tests
  • Cyclic fatigue tests
  • Combined test sequences

Connections

  • Solder contacts
  • Sintered joints
  • Interdiffusion joints
  • Adhesive bonds

“ZwickRoell Z250”

"ZwickRoell Z250" testing machine with temperature chamber.
© Fraunhofer IKTS
"ZwickRoell Z250" testing machine with temperature chamber.
Cyclic fatigue test to determine the softening behavior of solder samples.
© Fraunhofer IKTS
Cyclic fatigue test to determine the softening behavior of solder samples.
Broken solder sample with capacitive sensors for high-resolution displacement control.
© Fraunhofer IKTS
Broken solder sample with capacitive sensors for high-resolution displacement control.

Testing machine with temperature chamber

  • Temperature range: -70 °C to 250 °C
  • Force range: ± 5 kN
  • Force accuracy: ± 0,25 N
  • Displacement range: < 1000 µm (capacitive)
  • Displacement accuracy: ± 50 nm

Testing machine with high temperature chamber

  • Temperature range: 200 °C to 900 °C
  • Force range: ± 90 kN
  • Force accuracy: ± 2 N
  • Travel range: < 100 mm (crosshead)
  • Travel accuracy: ± 1 µm

Testing machine without temperature chamber

  • Temperature range: Room temperature, if necessary with local temperature control
  • Force range: ± 250 kN
  • Force accuracy: ± 2 N
  • Travel range: < 100 mm (tactile)
  • Travel accuracy: ± 1 µm

Test specimen holder  

  • Tension-compression mount
  • Wedge tension holder
  • Compression fixture
  • 3-point bending fixture
  • Customized fixtures
    

Further testing machines

  • Further testing machines from Hegewald & Peschke in the force range 10 to 5000 N with temperature chamber in use.

“H&P inspect table”

"H&P inspect table" testing machine with temperature chamber.
© Fraunhofer IKTS
"H&P inspect table" testing machine with temperature chamber.
Peel test on printed circuit boards.
© Fraunhofer IKTS
Peel test on printed circuit boards.
Pressure test on potting materials with high-resolution capacitive displacement control.
© Fraunhofer IKTS
Pressure test on potting materials with high-resolution capacitive displacement control.

Testing machine with temperature chamber

  • Temperature range: -70 °C to 250 °C (freely programmable)
  • Force range A: ± 5 kN
  • Force accuracy A: ± 0.25 N
  • Force range B: ± 200 N
  • Force accuracy B: ± 0.01 N
  • Displacement measuring range transverse: < 500 mm
  • Displacement accuracy transverse: ± 1 µm
  • Capacitive displacement measuring range: < 20 mm (-50 to 200 °C)
  • Displacement accuracy capacitive: ± 7.5 nm

Test fixtures (compatible with ZwickRoell)

  • Tensile-compression fixture
  • Peel test pull-off fixture
  • Customized fixtures