This is a practical guide to Surface Science for researchers working in the Telecommunications Industry.
In this all-new guide you’ll learn all about:
Let’s dive right in.
In telecom hardware, many field failures start at a surface. A conformal coating that dewets over flux residue leaves a board open to moisture. A sealant that does not bond lets water into an enclosure, and a worn coating holds water on an antenna cover.
These are the places where wetting decides yield in telecom work:
The Dropometer drop shape analysis kit measures contact angle, surface and interfacial tension, surface free energy and sliding angle with one portable setup. Its method was validated against a KRUSS DSA100E in two peer reviewed papers. If you are new to the terms, start with wettability.
We use the following surface properties to understand the behavior of Telecommunications products and improve their quality.
Sample Image taken from Droplet Lab Tensiometer.
Young – Laplace Method
Polynomial Method
Ideally, when we place a drop on a solid surface, a unique angle exists between the liquid and the solid surface. We can calculate the value of this ideal contact angle (the so-called Young’s contact angle) using Young’s equation. In practice, due to surface geometry, roughness, heterogeneity, contamination, and deformation, the contact angle value on a surface is not necessarily a single consistent value but rather falls within a range. The upper and lower limits of this range are known as the advancing and receding contact angles, respectively. The values of advancing and receding contact angles for a solid surface are highly sensitive to many parameters, such as temperature, humidity, homogeneity, and minor contamination of the surface and liquid. For example, the advancing and receding contact angles of a surface can differ at different locations.
Practical surfaces and coatings naturally show contact angle hysteresis, indicating a range of equilibrium values. When we measure static contact angles, we get a single value within this range. Solely relying on static measurements poses problems, like poor repeatability and incomplete surface assessment regarding adhesion, cleanliness, roughness, and homogeneity.
In practical applications, we need to understand how easily a liquid spreads (advancing angle) and how easily it is removed (receding angle), such as in painting and cleaning. Measuring advancing and receding angles offers a holistic view of liquid-solid interaction, unlike static measurements, which yield an arbitrary value within the range.
This insight is crucial for real-world surfaces with variations, roughness, and dynamics, aiding industries like cosmetics, materials science, and biotechnology in designing effective surfaces and optimizing processes.
Learn how Contact Angle measurement is done on our Tensiometer
For a more complete understanding of Contact Angle measurement, read our Contact Angle measurement: The Definitive Guide
These reference measurements show how deionized water wets four standard substrates measured with the Droplet Lab Dropometer. Use them as visual and numerical benchmarks when you're checking your own sample preparation, treatments, and chemistry.
Full contact angle and surface energy datasets (including additional liquids and statistics) are available on our dataset hub.
The droplet images above are taken from the same benchmark series as our open dataset. For each substrate and probe liquid we report:
● Advancing and receding contact angles (and hysteresis)
● Derived surface energy (SFE) values based on multi-liquid measurements
● Measurement conditions, uncertainties, and sample preparation details
Comparing your own droplet shapes and angles against these references is a fast way to spot contamination, treatment drift, or unexpected changes in wettability.
This property measures the force that acts on the surface of a liquid, aiming to minimize its surface area.
Sample Image taken from Droplet Lab Tensiometer
Dynamic Surface Tension
Dynamic surface tension differs from static surface tension, which refers to the surface energy per unit area (or force acting per unit length along the edge of a liquid surface).
Static surface tension characterizes the equilibrium state of the liquid interface, while dynamic surface tension accounts for the kinetics of changes at the interface. These changes could involve the presence of surfactants, additives, or variations in temperature, pressure, and composition at the interface.
When to use Dynamic Surface Tension Measurement
Dynamic surface tension is essential for processes that involve rapid changes at the liquid-gas or liquid-liquid interface, such as droplet and bubble formation, coalescence (change in surface area), the behavior of foams, and the drying of paints (change in composition, e.g., evaporation of solvent). It is measured by analyzing the shape of a hanging droplet over time.
Dynamic surface tension applies to various industries, including cosmetics, coatings, pharmaceuticals, paint, food and beverage, and industrial processes, where understanding and controlling the behavior of liquid interfaces is essential for product quality and process efficiency.
Learn how Surface Tension measurement is done on our Tensiometer
For a more complete understanding of Surface Energy measurement, read our Surface Tension measurement: The Definitive Guide
Sample Image taken from Droplet Lab Tensiometer
Learn how Surface Energy measurement is done on our Tensiometer
For a more complete understanding of Surface Energy measurement, read our Surface Energy measurement: The Definitive Guide
For benchmark contact angle and surface energy values on glass, nylon, PMMA, and Teflon, see the Open Benchmark Data panel above or visit our Dataset Hub for full CSV downloads.
The sliding angle measures the angle at which a liquid film slides over a solid surface. It is commonly employed to assess the slip resistance of a surface.
Sample Image taken from Droplet Lab Tensiometer
Learn how Sliding Angle measurement is done on our Tensiometer
For a more complete understanding of Sliding Angle measurement, read our Sliding Angle Measurement: The Definitive Guide
Within the Telecommunications industry, several case studies exemplify the advantages of conducting surface property measurements.
Water that sits on an antenna cover or dish can add signal loss, so outdoor coatings are chosen to shed rain. Static contact angle shows how strongly a coating repels water, and sliding angle shows whether drops actually roll off.
Coatings wear with UV, abrasion and cleaning. Reading both angles before and after cleaning separates a worn coating from a dirty one, as set out in our hydrophobic coating verification use case. The sliding angle guide explains the tilt method.
Moisture on cable jackets and at cable entries can track into connectors and enclosures. Water contact angle on the jacket or insulation material shows how strongly it repels water, and how that changes after weathering or cleaning.
Where a cable enters a cabinet, the seal matters as much as the jacket. Our sealant application QC use case covers contact angle checks before and after sealing. For boards inside the enclosure, the IPC TM-650 page explains how a contact angle check sits beside ionic and insulation resistance tests.
Outdoor cabinets and housings collect dust and mud, which hold moisture against the surface. Surfaces where water drops roll off at a low tilt tend to carry loose dirt away, an effect described under the lotus effect.
Sliding angle on a tilt stage compares candidate coatings and paints on this point. Contact angle hysteresis shows how strongly drops pin to the surface. Track both over service life, as in our hydrophobic coating verification use case.
If you are interested in implementing these or any other applications, please contact us.
In an industry where precision reigns supreme, how can Telecommunications manufacturers ensure their products withstand scrutiny? The answer lies in standards and guidelines: the compass that guides them through the complex maze of quality and performance.
An industry readiness guideline that uses minimum surface energy (commonly ≥38 dyn/cm, i.e., ≥38 mN/m) measured immediately before conformal coating to indicate whether PCB surfaces are likely to wet and hold coating. It is best operationalized as a repeatable QC gate using fixed-time contact angle and/or computed surface free energy (SFE) rather than subjective dyne-pen interpretation.
Use right before the conformal coating station (or right after the final clean/plasma step) to prevent pullback/fisheyes/non-wet defects from entering coating.
Use as a trendable check to confirm washer/plasma stability and to pinpoint drift or localized contamination that causes intermittent coating failures.
Treat “≥38 dyn/cm” as a starting target that must be validated against your coating chemistry, board materials, and defect outcomes. Dyne level/wetting tension and SFE are related screening concepts but not identical quantities, so lock your SOP to one method and correlate to results.
We hope this guide showed you how to apply surface science in the Telecommunications industry.
Now we’d like to turn it over to you:
Feel free to leave a comment below—we’d love to hear from you.
Start with the failure you see most. Use water contact angle on boards before conformal coating, and on sealant joints before sealing. Use sliding angle together with contact angle for water repellent outdoor coatings. Use surface tension for fluxes and coating liquids that must wet a surface. Our contact angle and sliding angle guides explain each method.
Yes, as a screen. Water contact angle at mapped areas, compared with a board cleaned by a validated process, flags non ionic films such as silicone, rosin residue and handling oils. It does not measure ionic cleanliness, insulation resistance or coating adhesion. Keep drops off areas that go to ionic or SIR testing, because water dissolves ionic residue. See PCB surface prep.
No. IPC TM-650 is the IPC manual of test methods for boards and assemblies, and no current method in it measures contact angle. IPC J-STD-003 tests solderability with molten solder, which the Dropometer cannot test. A flux surface tension or finish contact angle is a check before soldering or coating, and any limit must come from your own correlation study.
Measure water contact angle on the cleaned joint before you apply sealant, and compare it with a clean reference. After cure, measure contact angle and roll off on the bead to confirm it sheds water. This does not measure bond strength or movement capability, so keep your peel and pull tests. See sealant beading and application QC.
A high static contact angle shows a surface repels water, but drops can still pin and stay in place. Sliding angle shows the tilt at which a drop starts to move, and contact angle hysteresis shows how strongly it pins. Drop volume changes the sliding angle, so keep it fixed between tests. See roll off and sliding angle.
Yes, by the pendant drop method at room temperature. A flux surface tension reading can flag lot drift or solvent loss before soldering, because solder only wets a pad the flux has already wet. It does not show whether solder will wet the pad, which needs the molten solder tests in IPC J-STD-003. See our surface tension guide.
The drop shape method was validated against a KRUSS DSA100E in two peer reviewed papers, one in Review of Scientific Instruments and one in Colloids and Surfaces A. Published contact angle accuracy is 0.35 degrees. Automatic edge and baseline detection gives the same reading from the same image. See our validation papers.
