The Company
AST Products, Inc. develops and markets surface analytical
instruments for use in research and development, manufacturing
process control and quality control. Our primary products are VCA
(Video Contact Angle) Systems, computerized video image based
instruments for quantitative measurements of surface conditions
based on contact angle analysis. The results are accurate, reliable and
highly reproducible.
The VCA Systems are designed for scientists and engineers to easily
install, operate and obtain the information they need in a user-friendly
format. The ability to produce precise and expedient surface analysis
improves decision making and increases productivity in laboratory
research, quality control and engineering processing.
Contact angle measurement characterizes the interfacial tension
between a solid and a liquid drop. The technique provides a simple
method to generate a great amount of information for surface
analysis. And because the technique is extremely surface sensitive, it
can be used in many laboratory and industrial applications.
Measurements |
Applications |
Industries |
Surface
Energy
Surface
Tension
Bondability
Wettability |
Surface
Cleanliness
Wafer
Inspection
HMDS Coating
Control
Primer
Preparation
Coating
assessment
Coating Quality
Material
Research
Adhesion Study |
Semiconductor
Flat Panel Display
Hard Disk
Microelectronics
Chemical/Biochemical
Materials
Paper
Painting
Adhesives
Automotive
Aerospace |
The Technology - Contact angle measurement
Contact angle measurement is a simplified
method of characterizing the interfacial
tension present between a solid, a liquid,
and a vapor. When a droplet of a high
surface tension liquid rests on a solid of
low surface energy, the liquid surface
tension will cause the droplet to form a
spherical shape (lowest energy shape);
one example is the way water droplets
bead up on the surface of a freshly waxed car. Conversely, when the
solid surface energy exceeds the liquid surface tension, the droplet is a
flatter, lower profile shape. This is easily seen when a red wine droplet
wets, or sheets the surface of a glass.
By viewing small droplets of liquid on a surface in profile, the effects
of interfacial tension can be readily observed. In order to define these
droplet profiles, a line tangent to the curve of the droplet is drawn at
the point when the droplet intersects the solid surface. The angle
formed by this tangent line and the solid surface is called the contact
angle. Historically, contact angle measurements have been conducted
using an optical instrument which required the operator to align a
fiducial line with the edge of the droplet profile. This method is tedious
and by its nature, subjective. Data was rarely reproducible especially
from operator to operator, and repetitive measurements caused a
great deal of operator discomfort.
AST Products's VCA Systems utilize precision optics and CCD
cameras in conjunction with image processing hardware and software
to perform contact angle analysis quickly, easily, and accurately. In
practice a droplet of liquid is dispensed onto the surface of interest,
then a CCD camera examines the profile of the droplet displayed on a
computer screen. The image is captured into the computer memory
and analyzed to determine its shape. The computer software then
calculates the tangent to the droplet and computes the contact angle.
Due to the increased accuracy and reliability of these new systems,
contact angle measurement is being utilized in new ways never possible
before. For example, silicon wafers are being analyzed for surface
cleanliness and quality. Also, materials researchers in the biomedical
industry are using contact angle analysis to study the interfacial action
between blood and implant materials such as plastics, ceramics, etc.
Contact lens manufacturers find that this method of analysis can
predict wearer comfort.
