Fretting Corrosion of Tin Contacts -- A Growing Problem in the Automotive Industry
A review paper by Joseph Haimovich, PhD, Senior Consultant
This paper is a concise review of the current problems with use of the tin finish contacts in automotive electronics. It briefly describes the background of the issues, and points to potential solutions.
APEX EIC, LLC Statement Regarding the COVID-19 Pandemic Situation
To comply with State COVID-19 guidelines APEX experts are currently working from home. You may contact us as normal, either by phone, by email, or through this website's Contact Us page.
Until these restrictions are lifted we cannot have face-to-face meetings. In the interim we can arrange a remote meeting (via such apps as ZOOM, or another program).
We also work remotely with test laboratories and can arrange for remote test monitoring if such is necessary.
Our consulting capacity is not affected in any significant way by this situation, so APEX remains ready to provide the assistance to you require.
APEX consultants have once again been named as inventors on a patent granted for work done for a client.The patent for CONNECTORS FOR ELECTRICALLY ACTIVE GRID was issued to Worthington Armstrong Venture.
As is common, all patents resulting from APEX work are assigned to the APEX client commissioning the work.
APEX consultants are listed as inventors on no less than 12 patents assigned to various clients.
If you have need for new and unique creativity in developing new products, please contact APEX to take advantage of their consultants which have more than 300 patents issued listing them as the inventors.
APEX also provides patent assessments and serves as expert witness during infringement suits and reexaminations.
Apex Electrical Interconnection Consultants, LLC (APEX) continues to publish short educational presentations using the available social media channels, specifically the YouTube. The presentation by George Bedorf (APEX Principal Consultant) on problem solving (here is the link to it "Problem Solving 8D") was posted on 8/5/13 and accumulated several thousand views. A new presentation by Edward Bock (APEX Senior Consultant), "Typical Connector Failure Modes and Mechanisms", was recently posted on YouTube. It was narrated by Ron Locati, APEX Principal Consultant.
If you are feeling secure because an exclusive design or end product contains various unique and patented components, you may want to think again Patent infringement litigation is on the rise. Companies are increasingly willing to enforce their patents, as noted by the following news clips:
"The number of new patent complaints increased by nearly 15 percent in 2015 over the year before, and intellectual property attorneys say they are being pushed to take on more work as law firms stretch their resources to adapt to the influx of litigation".
"The record number of patent suits filed in (one Federal District) has created such an intense workload that it is putting a squeeze on the judicial system, as the number of patent suits filed there in 2015 shot up 77 percent over 2014”.
There are usually several Design Reviews conducted throughout the New Product Development cycle for electrical connectors. These reviews occur when the product is ready to pass from one of the several development phases to another. The primary purpose of a design review is to evaluate the ability of the outcome of design and development activities to meet requirements. The Design Review also provides a forum for all those involved in some aspect of the new product, to voice his or her opinions, concerns and approvals. This paper describes some of the topics required for the development and release of a typical new connector, such as one having stamped and formed contacts assembled into a polymeric housing. .
Failure analysis investigation requires at least two ingredients: experts and technical means. This article briefly touches on the current expert situation in the US, particularly the effects of globalization. It also describes some of the technical methods used in failure investigation, starting with simple inspection, often aided by an optical microscope, and progressing to more advanced techniques, such as scanning electron microscopy (SEM) and X-ray radiography. In case of SEM it describes three main modes of this technology - secondary electron imaging (the most common), back-scatter electron imaging, and energy dispersive X-ray analysis. For radiography, it starts with regular high-magnification radiography that allows internal investigation of increasingly smaller parts, and proceeds to a full computer-aided tomography on a small and down to microscopic scale (micro-CT).
There are fundamentally three specific elements of an electrical contact that are used within a multiple position connector. A multiple position connector for this purpose is defined as one which contains a molded plastic housing and a series of contacts that are attached to wires or printed circuit boards and installed into the molded housing. The contacts may be installed either before (ex., insulation displacement) or after (ex., crimp-snap) the wires have been attached. The contact elements are:
Separable Interface “Front End”
Permanent Interface “Back End”
Contact Retention Area
This article details several of the important design considerations for each of the three elements.
Single Mode Connector Attenuation Estimation Using Monte Carlo Simulation
Randy M. Manning, Senior Consultant
An optical fiber connector is a mechanical component that transfers light between two fibers or between a fiber and an active device such as a transmitter or receiver. A connector is intended to easily mate and un-mate repeatedly over its service lifetime. A permanent or semi-permanent connection between two fibers is called a splice.
How to Successfully Launch a New Connector Product
William Garver, Principal Consultant
Release/Launch, is a very critical phase in the process, but it is the one that is often overlooked or not recognized for the importance it contributes to a total process. This article will address the skills needed that may be used to facilitate this process. Strong Marketing skills are necessary to lead this phase.
Ron Locati, Principal Consultant, and Ed Reynolds, Principal Consultant
Connectors retain their electrical contacts within an insulating housing. Some retention mechanisms are more reliable than others. Serious issues can arise if the contacts are not assembled properly, or if the design of the retention device is not robust. This paper focuses on user-installed contacts, and addresses the importance of design, materials, handling, and other factors that assure good contact / housing retention.
In this short discourse we discuss the consequences of residual stress that had developed in a contact beam that had been subjected to stresses beyond the materials elastic limit. We intend to show that residual stress may be beneficial, or if not properly configured, may actually be very harmful to a contact spring..
Connectors are made from plastic and metal. The selection of these materials, including metal finishing, along with very precise and detailed mechanical parameters, are described on production drawings and related specifications. Connectors that meet all the specified design requirements are manufactured and tested to validate the connector performance. A test report and product specification provides proof that the design satisfies the customers’ requirements. Often, connector performance problems in customers’ applications are a result of product that was not manufactured to specified design requirements. Manufacturing process validation will reduce the risk that this will occur..
Required Skills for the Manufacturing Phase of Connector Development
William Garver, Principal Consultant, and George Bedorf, Principal Consultant
This article highlights not only the skills needed but also some tools that may be used to facilitate the process. Individuals having broad experience in manufacturing and materials management disciplines are needed in this phase. By this time, the product design is well documented and the detailed drawings completed both for the product and tooling. The development team activities will emphasize coordination with suppliers of components and finalization of assembly tooling and equipment. The tooling designs will be based upon both the sales forecast and the connector design requirements.
Contact Design Considerations For Long-Term Reliability
Ed M. Bock, Jr., Senior Consultant
For those critical electrical contact applications where the consequences of failure are severe and long-term reliability is paramount, reliance is customarily placed on noble metal finishes. Gold is by far the noble metal finish of choice. Gold, of the proper thickness and with an appropriate underplate, will form little or no tarnish film. This note will discuss reliability with respect to the ability of a contact system to operate successfully in spite of external contamination factors - the presence of/ entrapment of non-conducting material at the contact interface.
Silver - A Superior Finish for High Current Applications
Ed M. Bock, Jr., Senior Consultant
Connector designers have available a wide selection of finishes to consider for high current applications, both noble as well as non-noble metals. The choice would consider performance as well as cost aspects. Failures of high current contacts are somewhat distinct from those of signal contacts, which in that case are primarily associated with loss of information. In contrast, the failure of a high current contact could involve something as catastrophic as the initiation of a fire, with its associated risks.
In this short discourse, we will focus on silver and discuss a number of attributes that characterize it as a finish for high current applications. Silver has the highest value of electrical conductivity of any material - this is clearly a significant factor when considering the ability of a contact to carry current. Silver is “semi-noble”, in that although oxide formation is mitigated, it is susceptible to the formation of tarnish films. As with noble metals, silver will not degrade as a consequence of fretting corrosion. For electrical contacts, by utilizing the recommended normal forces and plating thicknesses, successful performance (in spite of tarnish formation) can be expected.
Many connectors and related components are subject to joining processes, which primarily involve soldering.The quality of these processes can be a key factor in component performance.The article covers basics of soldering, such as conditions necessary for solder to wet the substrate.It discusses interaction of solder with substrate such as substrate dissolution and formation of intermetallic compounds (IMCs).It also touches on soldering process issues related to obtaining adequate solder joint quality, and specific issues common to soldering of connectors versus those inherent to other components.Other stages of the entire manufacturing process prior to soldering could influence solder joint quality, including storage and transportation that can unfavorably affect solderability.In conclusion lead-free soldering is briefly discussed.
In a previous article, it was suggested that to assure a successful connector development and launch, companies need to optimize the talents of their employees to assure that critical needs are addressed. It was suggested that the New Product Process consists of four specific phases, each requiring specific and unique skill sets. They were identified as:
Creative/Innovative
Engineering/Scientific
Implementation/Manufacturing
Release/Launch
Unlike the earlier Concept/Innovative Phase, in which there is a small team of six to eight individuals working alone to create concepts and ideas and then getting together to brainstorm the concepts, this Engineering/Scientific phase requires many highly skilled engineers spanning all aspects of product and manufacturing design. To be effective, it takes an interactive team of people from each discipline working in close cooperation with each other.
In a previous article, it was suggested that to assure a successful product development and launch, manufacturers need to optimize the talents of their employees to be sure that critical needs are addressed. It was suggested that the new product process consists of four specific phases, each requiring specific and different skill sets.
In this article, the first of the four phases, the Creative/Innovative section, will be developed in more detail. It will address not only the skills needed but also some tools that may be used to facilitate the process.
Necessary Skills for Successful New Connector Development
William Garver, Principal Consultant
Successful new product developments and product release to the market requires that a company recognize and implement a structure to optimize the talents and skills of the staff and in creating an effective organization to assure that the critical needs are addressed.
The new product process consists of four specific phases. They are identified as:
Why Even Minor Increases in Contact Resistance Matter
Ed M. Bock, Jr., Senior Consultant
When a contact is mated, only a relatively small area is actually touching.All of the current must flow through this small area – the actual contact interface.Because the current is constricted to flow through this zone of contact, the resistance associated with this current constriction is called “constriction resistance”.Connector designers understand that many variables impact contact area (normal force, materials, surface finish, environment, etc.), and how important this issue is for the contacts to adequately do their job.
Did you ever buy the lowest cost item, only to find out that the cost to use or own it was much more than you had expected? Quite often that is the case with connectors. Connectors are frequently selected based on purchase price without fully considering the costs linked with using them..
Many times when there are field problems with a product that tie to a specific connector, the question is asked: “Who selected that crappy connector in the first place?”The answer is often not who selected the connector in the first place, but who selected it in the last place.
Once several manufacturers’ connectors have been evaluated for a specific application, it is likely that the ultimate selection will be made from at least three or four manufacturers and maybe more if the connector is an industry standard.It then becomes necessary to establish a method to select the best supplier.
Electrical connectors are mechanical components that serve an electrical function.In addition to carrying electrical current at a specified voltage, connectors either enable interconnection of components during the assembly process or enable the user to easily disconnect and reconnect different parts of the equipment.
The connector industry has witnessed significant erosion of its talent base in recent decades.Because this has occurred bit by bit over a long period of time, few may have noticed how the industry has changed.
Connectors, unfortunately, may contribute to an unacceptably high product failure rate. One reason for this is that connectors are typically a low priority in the initial design phase of the system.
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