The Thermomechanical Analysis of Polymers

Key Takeaways

• What thermomechanical analysis is. 

• How thermomechanical analysis works. 

• How to increase the sensitivity of thermomechanical analysis. 

Polymers in electronics

In the electronics industry, a wide variety of polymers are used in the manufacturing of circuit boards, cable insulation, adhesives, encapsulants, and molded products. Polymers are also used in the fabrication of integrated circuits as resist materials and for optical recording. Polymers are used in electronics to provide mechanical support and electrical insulation. As electronic devices operate at high temperatures, the thermal and mechanical properties of polymers become influential, and how they undergo variations with temperature must be analyzed. To do this, thermomechanical analysis is commonly used for assessing the thermal and mechanical properties of polymers. 

Thermal Analysis of Polymers

Thermal analysis of polymers is a traditional analysis technique used to check the genuineness of polymers. Thermal analysis consists of a set of methods to study the behavior of polymers under controlled temperature conditions. Well-established methods such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) are used for behavioral analysis of the polymers. Thermomechanical analysis (TMA) is another method used to study the expansion behavior and physical transitions of polymers.  

What Is Thermomechanical Analysis?

Thermomechanical analysis is an excellent thermal analysis technique used to measure the thermal expansion and shrinkage behavior of polymers. TMA measures the dimensional changes in the material as a function of time, temperature, and applied force. We can measure the coefficient of thermal expansion and compression modulus, such as Young’s Modulus, using this analysis method. TMA can be used to study thermal behavioral changes in thermosets, thermoplastics, adhesives, coatings, elastomers, metals, fibers, ceramics, films, and composites.

TMA is the best method to study the variations in mechanical properties of a material caused by physical and chemical transitions. The major transitions involve melting, crystallization, glass transitions, and curing. By using the TMA technique, the softening temperature of the materials can be obtained. TMA is helpful in determining the weak physical transitions of the materials under test. These physical transitions influence the modulus, delamination, and curing of the material, and their values also vary with transitions.

How Does Thermomechanical Analysis Work?

In the thermal analysis technique of TMA, the material under test is placed in a furnace. The material is connected to a probe from the force generator. To measure dimensional changes, a probe is connected to the material, which goes to the length detector. Depending on the choice of measurements to be made, other probes can be connected to the material. Thermocouple sensors are placed close to the material under test for temperature measurements.

The material under test is subjected to controlled temperature in the furnace and force is applied to the material using the force generator through the probe. The force or stress applied can be torsional, compressive, tensive, or flexural. Under force, the material undergoes deformation such as softening or thermal expansion with respect to the temperature. The linear variable differential transformer (LVDT) senses the displacement by the length detector. 

Increasing the Sensitivity of TMA

Thermomechanical analysis is more sensitive than other thermal analysis techniques used for polymer characterization in electronics. The sensitivity of TMA can be increased by using oscillating forces such as triangular, sinusoidal, or rectangular forces. The oscillating forces give oscillating responses, which are significant in increasing the sensitivity of TMA analysis.

With thermomechanical analysis, determining the thermal and mechanical properties of polymer electronics packaging is simple. Cadence’s software can help in analyzing the effectiveness of electronics packaging, encapsulants, and insulation using polymers.

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