Bonding - Sealing - Contacting: Failure Analysis

The Department of Functional Materials offers comprehensive testing procedures and methods for joining materials - both at the development stage and in the event of failure.

Failure analysis

The Department of Functional Materials is expanding its portfolio to include the topic of failure analysis for adhesively bonded, sealed and contacted joins. The department covers these topics from the development of scientific principles to their application in industrial environments. Interdisciplinary teams from the field of surface and materials engineering handle failure analysis enquiries concerning adhesives, sealants and multi-material contacts.

The experience gained from more than 50 years of research and development work in surface engineering, the highly diverse expertise of the scientists and the available laboratories and test facilities in our technical centers enable us to provide services and carry out research and development orders both promptly and to a high standard.

Adhesive bonding, sealing and contacting are methods used in almost all product segments for permanent joins. The complexity of these topics presents both manufacturers and research institutes with new challenges time and again. For example, joining different material combinations is often problematic with regard to the long-term stability of the join, as well as compatibility with solvents (battery production) and the drying process. Furthermore, existing application processes must be adapted for newly developed joining materials so that they can be processed. In a first step, this includes in-depth failure analyses.

Range of failure analysis services:

• Mechanical testing of (defective) joins with a  tensile testing machine (based on DIN 1465) and bead peel test (based on DIN 54457)
• Thermal characterization by means of dynamic differential scanning calorimetry (DSC), laser flash method (LFA), thermogravimetry (TGA)
• Ageing- and stress tests in climate chambers (based on DIN 50017, DIN EN ISO 9142, DIN 54456, DIN 50016)
• Measurement of surface energy, adhesion
• Element analysis via EDX measurement
• Research services in the field of non-destructive testing

Analysis of adhesives and sealants

To assess the processing characteristics and application potential of adhesives, fundamental knowledge of their material properties is required. In particular, thermal and rheological characterization methods can provide decisive information. These methods can be used to determine application parameters such as processing time (pot life), viscosity, hardness and curing conditions, which are instrumental in evaluating the possibilities for use and the choice of application. In addition, mechanical and optical characterizations make it possible to evaluate the tensile and adhesive strength of an adhesive and to optically analyze fractures.

Application

Material selection - determination and evaluation of adhesive and sealant formulations

Process definition - process selection based on determined processing properties

Failure analysis - evaluation of adhesives and sealants under different environmental conditions

Functionalization - formulation of functional adhesives and sealants

Thermal characterization

• Differential scanning calorimetry (DSC): temperature transition measurements (Tg), determination of spec. heat capacity, crystallization processes, cross-linking and curing reactions
• Thermogravimetric analysis (TGA): thermal stability, determination of volatile components
• Laser Flash Analysis (LFA): determination of thermal conductivity
• Climate chamber: determination of long-term stability, climate change tests (temperature change test, humidity test, creep and relaxation tests at different levels of humidity)
• Thermal image analysis (IR camera, pyrometer): snapshot, heat distribution, long-term IR emission tests

Rheological characterization

• Rheometer: characterization of flow and deformation properties

Mechanical characterization

• Tensile testing machine: tensile strength, adhesive strength, shear strength

Optical characterization

• UV-VIS spectrophotometer: transmission, absorption and reflection measurements
• Laser microscope: surface roughness, cross-section analysis, layer thickness measurement (3D)
• Optical microscope: surface analysis

Electrical characterization

• Four-point measuring device (surface resistance, spec. resistance)
• Potentiostat
• Current/voltage measuring instruments

Process selection and formulation of adhesives and sealants

Application equipment

• Automatic dispenser (reproducible dosing of low to high viscosity materials)
• Hot press
• Spray robot
• Spray guns
• Screen printing system, semi-automatic/manual
• Roll-to-roll system (continuous with slot nozzle)
• Doctor blade system
• Dip coater
• Pad printing machine
• Ultrasonic spraying system
• High-tech coating plant (discontinuous with fishtail nozzle)

Dispersing equipment

• Dispersing device according to rotor-stator principle (Filmix, Ultra Turrax)
• Stirrers (dissolvers, IKA stirrers)
• Ultrasonic sonotrodes
• Ultrasonic baths
• Three roll mill
• Intensive mixer
• Inline mixer
• Laboratory extruder
• Lab kneader
• Injection molding plant