Stress Relaxation I Mechanisms, Materials and Temperature In the metallurgical world, stress relaxation is defined as a time-dependent loss in stress at constant strain. OK, you may ask, but what does that have to do with connectors? It’s all about contact force. The contact normal force is a critical design parameter for connectors, because theRead More

Hertz Stress II Achieving the Right Degree of Resistance In the first Hertz stress article, I cited two limitations of Hertz stress as a connector design parameter. First, a Hertz stress value can be realized by different combinations of contact force and contact geometry, each producing different values of connector contact resistance. Second, variations inRead More

Dr. Bob on Hertz Stress as a Connector Design Parameter I was looking for some information in my files a few weeks ago, when I came across a folder entitled “Hertz Stress.” My mind leapt back 20 years as I recalled discussions that the concept had raised at that time. Using Hertz stress as aRead More

Power Distribution II Signal Contacts in Parallel This is the final article in our series about the distribution of current in power applications. In the previous article in this series, the topic was distribution of current using dedicated high current, several tens of amperes, contacts.  This article will address the use of multiple signal—low current,Read More

Power Contacts and Connectors Part 1: Power Distribution Today, there are three different approaches to power distribution in connectors, particularly, on current distribution. They include individual high-current contacts, multiple low-current contacts in parallel, and hybrids, which use both approaches in the same housing. Each approach has its advantages and limitations. Let’s begin with high-current contacts,Read More

Power Contacts/Connectors Part III: Current Rating 2 This week, let’s examine the current rating test program, which includes the measurements to be made and the conditioning and exposures to be applied in connector testing. Figure 1 includes an example program. A program of this general nature is under consideration in ECA CE-2.0 National Connector andRead More

Power Contacts/Connectors Part III: Current Rating 1 A number of issues need resolution in order to perform a current rating test program. Both practical and philosophical issues should be taken into consideration as you embark on this process. We first discuss the practical issues. The relevant document for this discussion is EIA 364 D: TP-70B,Read More

Power Contacts/Connectors Part II: Current Concerns Before we begin discussing current rating, let’s define the types of current a contact or connector may carry. There are four different current types: Transient, overload, steady state, and intermittent, also called duty cycle, currents. Figure 1 illustrates the first three current types in an induction motor application. RegionRead More

Power Contacts and Connectors Part I: What is Power? Understanding power is critical to the design of power contacts and connectors. By presenting a six-part series exploring these specialty contacts, I hope to empower you to make the best design decisions the next time you embark on a project. We’ll begin by defining what isRead More

Dr. Bob on Contact Spring Material Selection In the first article in this series I identified three contact spring material parameters of particular importance to electrical connectors. These parameters are elastic modulus, which affects contact normal force; yield strength, which also affects contact normal force; and conductivity, which affects the current carrying capacity of aRead More

Dr. Bob on Copper Alloy Metallurgy Limitations This article will cover limited aspects of copper alloy metallurgy as they apply to electronic connectors. The majority of connectors use a copper alloy strip for both plug and receptacle contacts. As mentioned in the previous article, this is because of the balance of strength, formability, and conductivityRead More

Dr. Bob on Electrical/Electronic Connector Contact Spring Materials A functional description of the performance requirements for an electrical/electronic connector is that it must transfer an electronic signal or electrical power between two sub-units of an electrical/electronic system without unacceptable power loss or degradation in signal integrity. Also, it must maintain this capability consistently over multipleRead More