Tag Archives: contaminants
The water break test is a common way to test for surface cleanliness. It allows the user to test for the presence of hydrophobic contaminants, which can be detrimental to adhesion. It is usually considered non-destructive to the part because it uses only water.
To perform a water break test in accordance with the ASTM-F22 Handbook, the material is dipped in water and withdrawn vertically. The behavior of that water on the surface reveals the surface energy which is determined by the cleanliness level. If the surface is clean it will show high surface energy and the water will spread out due to its attraction to the surface. This strongly correlates to adhesion ability.
Water break is mostly used on metals to expose the presence of contaminants or after surface processes such as etching, anodizing, painting, priming, coating, grit-blasting, or sanding. However, these tests can be messy and sometimes can result in unintended contaminating due to impure water. The user must also allot a significant amount of time for the part to dry after the test. These tests require a trained user who can determine a “go” or “no go” result. This leads to subjectivity. Lastly, the test can lack sensitivity as a surface can visually appear clean, when it’s not.
In contrast, the Surface Analyst™ is sensitive to the top 2-3 molecular layers of a surface. By using a single drop of highly purified water, there is virtually no mess and no threat to the measurement surface. Furthermore, it’s a small, handheld, user friendly instrument, that has the ability to measure on almost any surface or surface orientation, regardless of shape or roughness. The automatic calculation of contact angle removes operator subjectivity. The Surface Analyst measures on a cleanliness scale as opposed to a binary go/no go result. So measurements taken with the Surface Analyst can more closely map out a surface’s characteristics.
The Importance of Surface Cleanliness
BTG Labs’ Surface Analyst™ is a fast, easy, accurate, nondestructive, handheld device. It uses contact angle to measure the cleanliness level of a surface. Understanding and defining surface cleanliness within manufacturing is necessary. How a manufacturer qualifies a properly prepared surface can differ depending on the surface preparation process and requirements. Measuring and monitoring surfaces applies to many different steps within the manufacturing procedure. Consequently, the Surface Analyst applies to situations like: data collection, process development, supplier verification, identifying present and potential issues, and anticipating possible contaminants.
Surface Preparation and So Much More
BTG Labs breaks down the 5 Primary Uses of the Surface Analyst. This demonstrates the multifaceted ways in which the Surface Analyst can refine surface preparation processes to reinforce reliable, consistent, and strong adhesive processes.
Elemental Threats to Circuit Boards
Today, the range of when and where we use electronics broadens constantly. Consequently, electronics encounter threats such as water, extreme temperatures, shock, and contaminants. A circuit board, the core of any electronic, makes it highly sensitive to these threats that cause damage and failure. Manufacturers protect the board’s components with conformal coating. Conformal coating, implemented in the manufacturing of circuit boards, provides protection against threatening contaminants, moisture, and even extreme temperatures. Conformal coating comes as either a specialized coating or a polymer film that conforms to the topography of a circuit board, thus forming a protective shield.
When coating anything, the surface must show a level of surface cleanliness for the coating to bond successfully. Furthermore, circuit boards in particular, require highly cleaned surfaces, because of their sensitivity to contaminants. So, managing surfaces in circuit board manufacturing is doubly important. The surface must be clean for the sake of the circuit board and for the success of the coating. …Read More
BTG Labs will be attending the SAE (Society of Automotive Engineers) AMS Aerospace Organization Coatings Committee (AMS G-8)’s annual meeting May 3-5. Dr. Giles Dillingham and Lucas Dillingham will present on “An Integrated Approach to Quantification of Contaminant Effects on Surface Sensitive Processes.” The presentation is based on a collaboration with Lockheed Martin Skunkworks under DARPA support about a new approach at studying surface contaminants. This new approach proposes studying contaminants according to their chemical structure rather than the conventional way which studies the effects of complex contaminant mixtures without identifying and studying individual contaminants. G-8, a branch of SAE, studies adhesive bonding of composites and composes the handbook for bonding composites in aircraft, as well as the publication of the CMH-17 Handbook. SAE strives to standardize language relevant to data generation, testing, and reporting of composites. Below is the abstract for Dr. Dillingham’s presentation.
An Integrated Approach to Quantification of Contaminant Effects on Surface Sensitive Processes ~ Lucas Dillingham, Giles Dillingham / BTG Labs
The detrimental effects of a contaminant are determined by i) the amount of the contaminant in the environment, ii) the affinity of the contaminant for the critical surface, and iii) the compatibility (i.e. solubility) of the contaminant in the adhesive or coating. The most common approach for evaluating contaminant effects has been to evaluate the effect of a complex blend of multiple contaminants. Because this approach provides no information as to what makes a given contaminant detrimental, it limits our ability to predict the effect of an untested contaminant. Developing an understanding of the relationship between contaminant structure and effect can lead to more intelligent design of surface preparation processes, more robust adhesive and coating formulations, and more reliable manufacturing processes.
BTG Lab’s Collaborations
This paper, written as part of an ongoing collaboration between BTG, Southwest Research Institute, and Lockheed Martin Skunkworks. Funded by the Defense Advanced Research Projects Agency (DARPA), the collaborators examine and develop techniques for engineering a certifiable bonded method for aircraft manufacturing. The use of composites is increasingly employed in aircraft manufacturing to replace titanum and aluminum. However, composites weaken by the use of fasteners such as bolts and rivets. This is where the implementation of adhesives comes in. The understanding of surfaces requires knowledge on how an adhesive will stick to the surface and the presence of contaminants.
A New Approach
Studying the effects and habits of contaminants can be an essential step in any bonding or adhesion process as a contaminant can significantly influence the success of an adhesive or bond. All surfaces contaminate upon exposure, making them inevitable to any process. Thus, understanding the relationship between a contaminant structure and the effect it has on a bond will help develop more productive monitoring procedures for preparation processes, stronger adhesives and coating formulations, and more reliable construction.
The current method to evaluate the effect of contaminants on a surface entails examining a complex cocktail of them. However, not all contaminants in the blend might exist in a given manufacturing environment. The cocktail method fails to inform us of the effects an individual contaminant will have on a surface.
Controlling Surface Condition in FIPG Application
Increasingly, FIPG processes are replacing traditional gaskets for a variety of automotive applications such as air filters, oil filters, door panels, and external engine parts. The advantages include cheaper material cost, higher throughput capability, ability for assembly at the supplier, and greater control over sealing processes. These advantages, however, come with processing challenges that the manufacturer must take into account; namely the surface of the part they are sealing.
Within the automotive industry, a common FIPG application is RTV (room-temperature-vulcanization). Defining and controlling surface condition prior to applying an RTV silicone sealant is critical for a successful seal. Variables such as inadequate cleaning, over-used washing fluid, excess oil contamination, and poor handling can wreak havoc on an RTV application process. This can lead to rework, customer complaints, and warranty claims after the customer purchases the product. So how does an OEM or supplier design and control an appropriate FIPG process that will be successful?
Handheld Solution for Verifying Surface Cleanliness
The Surface Analyst™ is an innovative handheld solution for use in the lab and on the factory floor. It reduces waste, rework, and recalls when poorly prepared substrate surfaces lead to bonding, coating, sealing, painting, or printing failure.
Using contact angle measurement, the Surface Analyst measures the cleanliness level of surfaces and determines preparedness for adhesion. Developed and manufactured by BTG Labs, it is a fast, easy, accurate, and nondestructive instrument for manufacturers with critical surface requirements. The Surface Analyst replaces legacy methods such as dyne and water break tests.
Measuring Contact Angle to Determine Surface Cleanliness
The Surface Analyst deposits a highly purified drop of water on the surface. In two seconds, it measures the contact angle and in turn, determines the cleanliness level of a substrate.
When a surface is clean, it emits high energy, and water–as a high energy molecule–spreads out on the surface, in attraction to other high energy molecules (Figure 1). A contaminated surface emits low energy and will cause water to bead up in attraction to itself rather than the low energy surface molecules (Figure 2).
By knowing the volume and area of a drop of water, the contact angle of the water against a given surface can be determined. The larger the contact angle, the more the water beads up on the surface – and therefore the lower the energy level of the surface.