Customer SUCCESS STORY
Optimizing the Production of Semiconductor Devices with the Help of Thermal Analysis and Rheology
A Field Report by Dr. Christian Dreier and Dr. Sven Hüttner, Development Engineers at Vishay Semiconductor GmbH
When it comes to analyzing the mechanical properties and viscoelastic behavior of polymers under various conditions and making reliable predictions about their long-term performance and durability, analytical instruments by NETZSCH Analyzing & Testing are usually close at hand.
Read our new Customer Success Story to learn how Vishay Semiconductor GmbH uses the NETZSCH dynamic-mechanical analyzer (DMA) and Kinexus rotational rheometer to predict the service life and stability of polymer materials employed in semiconductor devices.
At Home in the Global Semiconductor Industry
Vishay is a globally renowned manufacturer of discrete semiconductors and passive electronic components. These components are employed in a wide range of electronic circuits, particularly in the automotive, industrial, consumer electronic, and medical markets. They embody Vishay’s foundation as the The DNA of tech ®.
In addition to their Selb site, Vishay also has other manufacturing facilities in Germany. In Heilbronn, for example, Vishay Semiconductor GmbH produces semiconductors for optoelectronic applications. These include optical sensors for light and distance measurement, infrared LEDs, transmitters and receivers, and optocouplers. The so-called "front end", which includes semiconductor chip production, is located in Heilbronn. The "back ends", where the semiconductor chips are integrated into packages, are located in Malaysia and the Philippines, among other places.
Infrared-Light-Generating Semiconductor Devices
The TSAL4400 infrared emitter in a traditional 3-mm design and a high-performance IR LED from the VSMA series are shown here as examples.
The optically active part of the component is an infrared-light-generating semiconductor chip made of gallium arsenide. The electrical connection is achieved via a metal strip or legs which are used for creating contact. In order to optimally protect the semiconductor from damage, it is encapsulated in a polymer package.
Mechanical and Viscoelastic Characterization of Polymer Materials
The interaction of the materials used is very important, even in a simple 3-mm LED component such as this, because it determines the component’s stability in the face of thermal and mechanical StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress and ultimately its service life. Certain electronic components must be able to withstand temperatures between -55°C and 125°C without any problems. Especially with unfilled epoxy or silicone materials, it is important to adjust the thermal expansion, but this is not always possible. However, such materials must be used because only these provide the required transparency and the desired mechanical strength. The use of fillers to improve mechanical properties would have a negative impact on the optical light transmission.
Our objective was to better predict the service life and stability (without cracking or debonding) of the polymer materials and therefore of our components. This knowledge is particularly valuable in the development of components and in the evaluation of new materials. To this end, we use the NETZSCH Kinexus Lab+ rotational rheometer and the NETZSCH DMA 242 E Artemis for more precise characterization.
DMA (Dynamic Mechanical Analysis) is used to determine parameters such as the Young's modulus and Viscous modulusThe complex modulus (viscous component), loss modulus, or G’’, is the “imaginary” part of the samples the overall complex modulus. This viscous component indicates the liquid like, or out of phase, response of the sample being measurement. loss modulus or the associated Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition temperature. In addition, frequency- and temperature-dependent DMA measurements can be used to establish associated master curves.
For this purpose, samples were measured with our NETZSCH Artemis DMA in a temperature range from -40°C to +200°C in 3-point bending mode over various frequencies.
Further Analysis and Predictions with NETZSCH Proteus®
The measured spectra were processed directly in the NETZSCH Proteus® software to generate a Cole-Cole master curve.
Using the master curve and the time-temperature shift factors, the RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation behavior of the sample can be extrapolated over a long period of time. It is assumed that the material properties at high frequencies correspond to those at low temperatures and vice versa. In this way, the material properties are determined from the master curve and the displacement factors measured in the software in order to make more accurate predictions for finite element simulations, for example.
This analysis, which is directly supported by the NETZSCH Proteus® measurement software, allows us to calculate and simulate time-dependent parameters such as the RelaxationWhen a constant strain is applied to a rubber compound, the force necessary to maintain that strain is not constant but decreases with time; this behavior is known as stress relaxation. The process responsible for stress relaxation can be physical or chemical, and under normal conditions, both will occur at the same time. relaxation behavior and CreepCreep describes a time and temperature dependent plastic deformation under a constant force. When a constant force is applied to a rubber compound, the initial deformation obtained due to the application of the force is not fixed. The deformation will increase with time.creep in the respective components. These can then be designed to avoid weak points or to find high-performance materials.
In our long history with NETZSCH instruments, we have come to appreciate the reliability of the analytical instruments and the quality of the support. Excellent results can often be achieved by combining exciting questions with the high technical quality and expertise of the NETZSCH laboratory staff.
Dr. Christian Dreier and Dr. Sven Hüttner, thank you very much for these interesting insights in your research work!