C Scanning Acoustic Microscopy

Theory of Operation

The C-SAM works by alternately producing and receiving pulses of ultrasonic energy from 10- 200 MHz. Ultrasound will not transmit through air and the energy produced by an acoustical lens is focused on the acoustical subsurface on planes using water as the medium.

The ultrasound interacts within the solid, and the echoes reflected can be analyzed for information about the sample. Each interface within the sample transmits some ultrasonic energy, and reflects some energy. By compiling these echoes via a computer an image can be produced produced as the transducer is scanned over the sample. The different colors in the enhanced image represent different acoustical planes and topography within the sample.

As a result, any voids, cracks, delaminations, or other “air-filled” disbonds will show extremely high contrast, because the air reflects all of the energy. C-SAM has certain advantages over x-ray inspection (radiography) with the ability to focus at specific levels, it can give information about the size and depth of the defect.

Applications

• Inspection in ceramics, metals, and polymers porosity, voids and inclusions.
• Package sealing in the food processing industry.
• Welds and braze joints can be examined and voiding can be quantified with the imaging program.
• Ceramic chip capacitors can be inspected for internal cracks and delaminations.
• Tape automation bonds (TAB) can be evaluated for quality of the attach.
• Die attach voids (solder, silver filled epoxy) and disbonding caused by package interaction can be assessed.