For polymeric materials, microscopy provides useful information for the additive distribution (glass-fiber reinforcement, flame retardants, mineral additives, and etc) in a polymeric matrix.
For metallic materials, microscopy provides information about grain structure, physical continuity, surface topography, and measurements for applied surface finishes.
For composite materials such as printed circuit board (PCB) components and complex components, microscopy provides visualization of important connections, interfaces and structures.
The scanning electron microscope (SEM) images were performed on a JEOL 6460LV microscope. The SEM has two detectors to provide images based on the raster scanning of the electron beam. The secondary electron detector (SEI) measures scattered electrons from surface of the conductive sample. The backscatter electron detector provided images using three modes: BES, BEC and BET. The BEC mode provides images with a contrast dependent on chemical composition of the imaged material with the lighter contrast directly proportional to higher atomic number. The BET mode provides images with a contrast dependent on the topography (z-axis) of the imaged material. The BES (shadow) mode provides images with a combination of BEC and BET with the strength of the topography component increasing shadow value (1-10). Unless otherwise indicated SEM images are provided using BEC. The magnification for an SEM is a general reference based on the factor where X100 provides a pixel size of 1µm/pixel for the software's highest available scanning resolution which provides images of 1280 pixels x 960 pixels. The resolution of an SEM is more complicated than an optical microscope and is well presented in this reference.
SEM Resolution Limitation
The plating thickness (~100 nm) for the silver flash specified is below the appropriately discernable resolution for a coating which requires mounting and preparation. In optimal conditions, the SEM can discern metal colloid substrates with dimensions of 5-10 nm. The metal colloid substrate is perfectly conductive and formed as distinctive spherical structures. In this circumstance of a silver flash coating, there is difficulty discerning it distinctively from the mounting medium (which is partially insulating) and the body of the metal part with additional preparation issue of the last available polishing step has the limitation of using Nap with a 1 µm diamond polishing media.
The stereomicroscope (SMZ) images were provided by a Nikon SMZ-10 stereoscope and Olympus SC100 digital microscope camera. The SMZ technique provides images with minimal magnification which imitates the viewing of a surface by the human eye using reflected visible light. The Olympus SC100 digital microscope camera is a CMOS color camera with effective area of 6.12 mm x 4.59 mm, pixel size of 1.67 µm x 1.67 µm, and a maximum resolution of 3840 pixels x 2748 pixels.
The inverted light microscopy images were provided using an Olympus GX71F5 microscope (metallograph) and Olympus UC30 digital camera.
For polymeric materials, FT-IR provides the ability to identify the polymer type and identify major additives in the material such as flame retardants, minerals, and molding performance improvement compounds. The elemental analysis provided by EDS can also complement the identification and physical distribution for polymeric material additives.
For metallic materials, elemental analysis by EDS provides information to identify contaminates, composition of applied surface finishes, and degradation through corrosion processes. The alloy composition analysis by GDS provided metal alloy composition confirmation.
For composite materials such as printed circuit board (PCB) components and complex components, elemental analysis by EDS provides information to also identify contaminates and confirm composition for structures.
The material analysis method Fourier transform infrared spectroscopy (FT-IR) was provided by a Varian 4100 spectrometer and a diamond attenuated total reflectance (ATR) sample holder. The ATR also has the option of using a geranium crystal for analysis on samples that show absorbance artifacts when using the diamond ATR crystal. The measured FT-IR spectra represent a distinct pattern for the molecular structure of the analyzed materials. The FT-IR technique is more sensitive to the organic types of molecular bonding than inorganic bonds like those found in minerals. This pattern provides a result that can be matched using a database of reference FT-IR spectra. The lab uses the database software called KnowItAll® from the company BioRad. The BioRad software and database contains >200,000 searchable reference spectra..
The energy dispersive x-ray spectroscopy (EDS) results were provided by the EDAX Apollo X spectrometer coupled to the SEM. The EDS provides elemental detection of the surface being visualized by the SEM. The elemental detection is provided as a spectrum, line scan or mapping of the area surface with the location of the detected elements shown by color with the variation of intensity directly proportional to concentration. The elements detected will be identified using the element symbol and x-ray line.
The Glow Discharge Spectroscopy (GDS) was performed using the Leco GDS 500A spectrometer. The specified GDS has the ability to analyzed the following material types within common alloy ranges: copper, low alloy iron, stainless steel, zinc, aluminum and silver based contact materials.
For all material types, preparation allows imaging of the material structure.
For materials with surface finishes, the careful and appropriate preparation is an important step for analysis.
Materials samples come in all shapes and sizes. Often, the first step in analysis is isolating the portion of interest and preparing it appropriately through cutting using industrial tools. The following equipment is commonly utilized for specimen preparation: Struers Discotom 100 Automated Saw Cutting Machine, Struers Secotom 5 Saw Cutting Machine, drill press, and industrial bandsaws.
The specimens were prepared for imaging using the method, ASTM E 3-11. The sample specimens were hot mounted using Struers Polyfast, a carbon filed resin, and the Struers CitoPress-10 using the following settings: 180°C, 250 bar for 3.5 minutes. The measurement of the metallic coating thickness was determined using the scanning electron microscope (SEM) and energy dispersive x-ray spectrometer (EDS) based on ASTM B 748.
The specimens were prepared for imaging using the method, ASTM E 3-11. The sample specimens were cold mounted using Struers EpoFix, a slow-curing transparent two-part epoxy thermoset with a low 40°C peak curing temperature. The measurement of the metallic coating thickness was determined using the scanning electron microscope (SEM) and energy dispersive x-ray spectrometer (EDS) based on ASTM B 748.
The specimens were prepared for imaging using the method, ASTM E3-11. The measurement of the metallic coating thickness was determined using the scanning electron microscope (SEM) and energy dispersive x-ray spectrometer (EDS) based on ASTM B 748-90. The following equipment is commonly utilized for specimen preparation: Struers Discotom 100 Automated Saw Cutting Machine, Struers Secotom 5 Saw Cutting Machine, Struers CitoPress-10 Hot Mounting Press, Struers Tegramin-20 Specimen Polisher Machine, and Bandsaw.
For thermoplastic polymer materials, thermal analysis provides information to also identify and confirm polymer type using reference thermal transition: melting temperature, glass temperature, decomposition temperatures, and etc. Thermal analysis also provides indications of processing issues or contamination.
For thermoset polymer materials, thermal analysis provides information to identify polymer type, cure state and additives related to thermal transition and decomposition temperatures.
For metallic materials, thermal analysis provides information about soldier compositions and fuse performance.
General Information
The differential scanning calorimetry (DSC) testing was performed using a TA Instruments Q2000 model DSC (2012-2022) and a Perkin Elmer DSC7 (2008-2012). The material sample specimen used for analysis measured approximately 10-20mg. These methods are based on ASTM D 3418.
Four Step Method for Semi-Crystalline Polymer Analysis - DSC4
The DSC testing for a thermoplastic material involves four thermal curves. The first step (#1) is a heating thermal ramp that removes the thermal history from polymer. The second step (#2) is slow cooling thermal ramp allowing sufficient crystallization of the crystallites in the polymer. The third step (#3) is a second heating thermal ramp which shows the melting transitions from an equal basis for all analyzed specimens. The fourth step (#4) is very slow cooling thermal ramp that provides unique information about the crystallization behavior for the polymer macromolecules.
The DSC analysis of the specimens using four steps uses the following example parameters: step #1 - first heating step from 50°C-300°C at 10°C per minute, step #2 – first cooling step from 300°C-50°C at 10°C per minute, step #3 - second heating step from 50°C-300°C at 10°C per minute and step #4 – second cooling step from 300°C-50°C at 2.5°C per minute.
Three Step Method for Amorphous Polymer Analysis - DSCQ
The DSC analysis for amorphous polymers generally involves three steps: step #1 - first heating step from -65°C to 205°C at 20°C per minute, step #2 – quench cooling step from 205°C to -65°C at approximately 100°C per minute, step #3 - second heating step from -65°C to 500°C at 20°C per minute. The testing will provide a calculated glass transition (Tg) and additional thermal information for additives.
Three Step Method for Checking Curing in Thermoset Polymer Analysis -DSCC
The DSC analysis for thermoset materials for detecting thermal transitions involved three steps: step #1 - first heating step from 50°C-200°C at 5°C per minute, step #2 – cooling step from 200°C-50°C at 5°C per minute and step #3 - second heating step from 50°C-200°C at 5°C per minute. The first step (#1) is a heating thermal ramp that removes the thermal history from polymer. This step may also show exothermic transitions which may be related to remaining cure-based chemical reactions. The second step (#2) is slow cooling thermal ramp to return to initial temperatures. The third step (#3) is a second heating thermal ramp which shows the thermal state of the thermoset after the first heat ramp.
DSC References
ASTM Standard D3418, 2008, "Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry," ASTM International, West Conshohocken, PA, 2008, DOI: 10.1520/D3418-08, www.astm.org.
The thermogravimetric analysis (TGA) testing was performed using a TA Instruments Q500 model TGA (2012-2022) and a Perkin Elmer TGA7 (2008-2012). In TGA, an approximately 10 mg specimen portion is used for analysis.
All Purpose Method for All Polymer Types Analysis - TGA
The mass is measured while the temperature of the sample portion is raised from 50°C to 850°C at a rate of 10°C per minute. The temperature scan provides information on the degradation of the material sample dependent on temperature. During the TGA, the purge gas was switched from nitrogen to air at 800°C causing oxidative degradation of the sample. Thermal analysis by TGA on a sample specimen provides a unique curve based on a complicated thermal degradation pathway. This method is based on ASTM E 1131.
Incremental Specialty Method for All Polymer Types Analysis - TGASI
The mass is measured while the temperature is controlled by a maximum limit of mass loss (weight %) per minute. The temperature scan provides information on the material degradation dependent on the rate of degradation and helps to resolve different temperature dependent degradation processes.
TGA References
ASTM Standard E1131, 2008 (2014), "Standard Test Method for Compositional Analysis by Thermogravimetry," ASTM International, West Conshohocken, PA, 2014, DOI: 10.1520/E1131-08R14, www.astm.org
The dynamic hybrid rheometry (DHR) testing was performed using a TA Instruments DHR2 (2012-2022). DHR is a companion technique to Dynamic Mechanical Analysis (DMA) using torsion.
Melt flow Index rheological testing was performed using a Dynisco Series 4004 Kayeness Polymer Tester according to ASTM D1238 (or ISO 1133). The melt flow testing was performed at 300°C using a 1.2 kg weight.
For polymeric materials, microscopy provides useful information for the additive distribution (glass-fiber reinforcement, flame retardants, mineral additives, and etc) in a polymeric matrix.
For metallic materials, microscopy provides information about grain structure, physical continuity, surface topography, and measurements for applied surface finishes.
For composite materials such as printed circuit board (PCB) components and complex components, microscopy provides visualization of important connections, interfaces and structures.
The scanning electron microscope (SEM) images were performed on a JEOL 6460LV microscope. The SEM has two detectors to provide images based on the raster scanning of the electron beam. The secondary electron detector (SEI) measures scattered electrons from surface of the conductive sample. The backscatter electron detector provided images using three modes: BES, BEC and BET. The BEC mode provides images with a contrast dependent on chemical composition of the imaged material with the lighter contrast directly proportional to higher atomic number. The BET mode provides images with a contrast dependent on the topography (z-axis) of the imaged material. The BES (shadow) mode provides images with a combination of BEC and BET with the strength of the topography component increasing shadow value (1-10). Unless otherwise indicated SEM images are provided using BEC. The magnification for an SEM is a general reference based on the factor where X100 provides a pixel size of 1µm/pixel for the software's highest available scanning resolution which provides images of 1280 pixels x 960 pixels. The resolution of an SEM is more complicated than an optical microscope and is well presented in this reference.
SEM Resolution Limitation
The plating thickness (~100 nm) for the silver flash specified is below the appropriately discernable resolution for a coating which requires mounting and preparation. In optimal conditions, the SEM can discern metal colloid substrates with dimensions of 5-10 nm. The metal colloid substrate is perfectly conductive and formed as distinctive spherical structures. In this circumstance of a silver flash coating, there is difficulty discerning it distinctively from the mounting medium (which is partially insulating) and the body of the metal part with additional preparation issue of the last available polishing step has the limitation of using Nap with a 1 µm diamond polishing media.
The stereomicroscope (SMZ) images were provided by a Nikon SMZ-10 stereoscope and Olympus SC100 digital microscope camera. The SMZ technique provides images with minimal magnification which imitates the viewing of a surface by the human eye using reflected visible light. The Olympus SC100 digital microscope camera is a CMOS color camera with effective area of 6.12 mm x 4.59 mm, pixel size of 1.67 µm x 1.67 µm, and a maximum resolution of 3840 pixels x 2748 pixels.
The inverted light microscopy images were provided using an Olympus GX71F5 microscope (metallograph) and Olympus UC30 digital camera.