Surface Analysis
Scanning Electron Microscopy with Energy Dispersive X-ray (SEM/EDX)
Scanning Electron Microscopy (SEM) is a high resolution imaging technique, with a great depth of field. It shows topographical, structural and elemental information at magnifications of 10X to 200,000X. The use of Scanning Electron Microscopy (SEM) technology is an invaluable aid whether characterizing products or resolving failure analysis problems. Electrostatic discharge damage, contamination identification, and micro-crack location are only a few of the uses of SEM when performing failure analysis.
Failure Analysis
• Elemental Contamination identification
• Micro-crack / void location documentation
• High resolution ESD documentation
• High resolution Mechanical damage
Quality Control Evaluations
• Dimension verifications
• Plating / coating thickness
• Weld evaluation
Material Analysis
• Elemental analysis
• Surface roughness
• Metallurgical / interface evaluation
Energy Dispersive X-ray analysis (EDX)
During EDX Analysis, the specimen is bombarded with an electron beam inside the SEM. Those electrons collide with the specimen's own electrons, knocking some of them off in the process. When the electron is displaced, it gives up some of its energy by emitting an X-ray. Every element releases X-rays with unique amounts of energy during the transfer process. Thus, by measuring the amounts of energy present in the X-rays being released by a specimen during electron beam bombardment, the identity of the atom from which the X-ray was emitted can be established.
Field Emission Microanalysis with Energy Dispersive X-ray (FEM/EDX)
The FE-SEM is similar in nature to the SEM. The difference being that The FE generates its electron beam in a manor that allows for low energy imaging of samples. The advantage to this method is that a normally nonconductive sample may be imaged without having to sputter a conductive coating onto the surface. An example of the saving would be in wafer inspection where the low energies would allow for inspection without damage, thus allowing the wafer to be placed back into the process and utilized.
Fourier Transform Infra Red (FTIR)
FTIR defines the chemical composition of a sample by the amount of infrared light that is transmitted through or absorbed by the sample. The resulting computerized analysis is used to identify resins, to identify and quantify additives, and to determine the presence of copolymers.
Fourier Transform Infra Red Spectroscopy (FTIR) is useful in chemical structure identification, and/or composition analysis of:
* Solids * Powders * Polymers * Fabric * Films
* Pastes * Liquids * Dispersed solids * Emulsions * PCB Materials
In the electromagnetic spectrum, IR region can be separated into near, mid and far infra regions. Infrared spectroscopy use molecular motions, twisting, bending, rotating and vibration of atoms in molecules to identify the molecular structures based on absorption spectrum. The spectroscopist using the data can recognize chemical bonds and functional groups can be assigned (e.g. C=O stretching, C-H bending). Changes in the chemical structure or changes in the chemical environment are reflected by shifts in the frequency of absorption bands.
Scanning Auger Microscopy (SAM)
Scanning Auger Microscopy is also known as Auger Electron Spectroscopy (AES). This is a technique for the chemical analysis of surfaces of samples based on the Auger radiationless process. When an electron beam ionizes core level surface atom, the atom may decay to a lower energy state through an electronic rearrangement that leaves it in a doubly ionized state. The energy difference between these two states is given to the ejected Auger electron. This will have a kinetic energy characteristic of the parent atom. When the Auger transition occurs within a few angstroms of the surface, the Auger electrons may be ejected from the surface without loss of energy and give rise to peaks in the secondary electron energy distribution function. The energy and shape of these Auger features can be used to identify the composition of the solid surface within the first 100 Angstroms.
Electron Spectroscopy for Chemical Analysis = (ESCA)
Electron Spectroscopy for Chemical Analysis (ESCA) is also known as X-ray Photoelectron Spectroscopy (XPS). ESCA is an advanced surface analysis technique used for obtaining chemical information about the surfaces of materials. The process works by bombarding a sample with monochromatic x-rays, resulting in the emission of photoelectrons whose energies are characteristic of the parent elements within the sample.
Atoms associated with different chemical environments produce peaks with slightly different binding energies. These are known as chemical shifts. Distinct chemical states, which are close in energy, can be deconvoluted using peak fitting programs to give percent composition of each state.
Cleanliness Testing
In the manufacture of electronic circuits, components and assemblies, both performance and long-term reliability can be affected by the presence of ionic contamination. Residual ionic contamination can cause current leakage across insulating surfaces, as well as corrosion. This contamination along with humidity in the environment can cause the speed of circuit and assembly degradation to increase dramatically. The Ionograph allows for simple and accurate measurement of residual ionic contamination on PC board, components and assemblies.