![]() How can you mitigate the risk of unintended connector contact resistance? Stress relaxation has the potential to increase resistance because it can reduce contact force and the ability of the contact to “wipe” itself (both concepts are discussed in the next section).įor high-temperature, high-cycle environments, stress relaxation can be a major cause of contact resistance.Įxample of stress relaxation causing contact resistance. This deformation and change is often referred to as “stress relaxation.” Over time and/or with excessive use, material can become deformed and the shape of your contact can vary from what was originally intended. If contacts are covered in a bonding agent, dirt, or anything else that could disrupt the connection, contact resistance increases.Įxample of contamination causing contact resistance. Oxidation causes connector contacts to corrode-increasing contact resistance and causing a negative impact on the voltage passed through the connection.Ĭontamination happens when foreign debris finds its way onto the contact of a connector. When it comes to electrical connectors, oxidation occurs when the layer of oxides on a contact absorb moisture. Unfortunately, most metals are typically classified as “easily oxidized.” Film Resistanceįilm resistance describes the resistance created by the occurrence of unwanted resistive material on the surface (“film”) of the contact.įilm resistance has two sources: oxidation and contamination.īroadly speaking, oxidation describes the loss of electrons. In reality, due to the behavior of electrons beyond the scope of this blog post, even when two flat materials are perfectly pressed together, true contact will only be made at certain points.Įxample of constriction causing contact resistance. When two materials make contact, it is often assumed that electrons are flowing across the entire surface area of the materials. ConstrictionĬonstriction describes the narrowing of the true contact surface when two materials come into contact. That being said, contact resistance is typically caused by three culprits: constriction, film resistance, and stress relaxation. Instead, devices, connectors, and circuits are designed around the existence of contact resistance and-in most cases-are designed to prevent or mitigate the impact it might have. In general, contact resistance is not designed into a device, connector, or circuit. Resistors, which Merriam Webster defines as “a device that has electrical resistance and that is used in an electric circuit for protection, operation, or current control,” are a perfect example of this concept.Ĭontact resistance, however, is a different story. In fact, many energy-driven products (medical devices included) utilize mechanisms to control or introduce resistance. To be clear, the existence of resistance is not a bad thing. When two cables are connected and the voltage of the cables changes as an (mostly) unintended result of this connection, it is commonly caused by contact resistance.Ĭomparison of resistivity and contact resistance. Contact ResistanceĬontact resistance, on the other hand, describes the resistance faced when two conductors come into contact with each other. When someone says copper has low resistance, they’re referring to the resistivity of copper. Resistivity (sometimes referred to as “intrinsic resistance” or “material resistance”) describes the resistance of the material itself (at a given size and area). In talking about interconnect solutions, there are generally two broad categories of resistance: resistivity and contact resistance. That being said, elements that make good conductors (e.g., silver, copper, etc.) have low resistance, while elements that make good insulators (e.g., rubber, glass, etc.) tend to have high resistance. In other words, resistance describes the ability of a material to prevent/slow the flow of electricity. When talking about electrical components and circuits, resistance refers to the opposition of the flow of an electrical current. Recommended: Interconnect Solutions for Medical Devices What is contact resistance?īefore diving into contact resistance, it’s important to note what “resistance” is. In this blog post, we’ll discuss contact resistance, what causes it, how you can find it, and some of the ways you can prevent it. ![]() One of the potential causes of an electrical connection failure is unwanted/unknown levels of contact resistance. Understanding where a failure may happen and what could potentially cause it can help you develop better energy-driven medical devices. Unfortunately, there are many different ways an electrical connection can fail. The failure of a single electrical connection within an operating room can be fatal.
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