Connection technology as an electrical lifeline

With an extensive electromechanical portfolio, Würth Elektronik eiSos supports assembly designers as a system partner in close cooperation.

Here, Thomas Hess, FAE Electronic Interconnect & Electromechanical Solutions of Würth Elektronik eiSos, and Marisa Robles, Product Management/Technical Marketing eiCan of Würth Elektronik eiSos delve into the critical role of connectors and crimping technology in electronic assembly.

Connectors are the interface between the electronic assembly and the outside world. Factors such as increasing complexity and ever shorter product life cycles combined with increasing quality requirements make it difficult to select the right connectors. Seemingly simple solutions can harbour considerable risks if incorrectly specified, the consequences of which can sometimes be very expensive and time-consuming to rectify. A fail-safe connection is therefore essential.

However, the use of cabling can prove to be problematic. This is not only due to the complex design of the connectors, but also to the current requirements. These include the ever increasing electrical and mechanical demands, higher packing density with increasing miniaturisation of cables and connectors as well as the discrepancy between the requirements for halogen-free and the low flammability of cables and connectors.

Ensure rapid market launch

But what demands are being placed on today's connection solutions? Global Cloud computing, simulations, and the increasing use of artificial intelligence make it easier for developers to bring new devices to product maturity quickly. It is obvious that a significantly shorter development time not only boosts the planned market launch of a product, but also secures advantages over the competition. Nevertheless, this must not be at the expense of quality and safety.

However, practice shows that cables are often the last components that developers select during their system design. In fact, cables are the lifeline of electrical systems. The reliability of a cable is based on its durability and robustness as well as its signal integrity. It starts with the choice of materials and must be ensured during both cable manufacture and cable processing. The ideal cable system should therefore be designed to function properly in any environment over the entire life of the product. Crimping technology for connectors is the linchpin.

Crimping technology as an indispensable link

The crimp joining process makes it possible to connect two components one with another, using a pressing process – ideally as a homogeneous, hard-to-remove connection between a conductor and a suitable connecting element.

Crimping is considered an alternative to soldering or welding technology and guarantees a high level of electrical and mechanical safety. Essential requirements for crimp connections are defined in the DIN EN 60352-2 standard. This also describes test methods and provides important application notes. If the crimping process is carried out correctly, the result is a virtually gas-tight connection, as the deformation of the crimp sleeve and the strands creates a structure that is largely sealed off from oxygen and therefore well protected from oxidation on the inside. In large-scale production, fully automatic crimping machines are usually used, which allow a variety of processing methods.

If prototypes or small series are to be produced, there is no way around crimping pliers. However, it is important to choose the right tool: a distinction is made between crimping tools with fixed or interchangeable dies. There are also single-station and multi-station tools. While single-station tools can be used to process all cross-sections approved for the tool without the need for further adjustments, multi-station tools have several cavities for different cross-sections. With the latter, care must be taken to ensure that each crimp contact is crimped in the appropriate cavity.

However, crimping errors can quickly occur, for example because insufficient force has been applied or the wrong crimping tool has been used, resulting in partially crimped strands. As a result, the contact resistance between the strands and the crimp contact increases. It is also possible that the incompletely crimped stranded wire can be pulled out of the crimp barrel, which can lead to product failure. On the other hand, an over-crimped crimp connection carries the risk of individual stranded conductors being sheared off. As a result, the current-carrying capacity of the connection decreases unacceptably due to the reduced cross-section.

System partner working closely together

As a rule, manufacturers assume the warranty for their products across the entire value chain, which is why the responsibility to avoid failures in the field as far as possible is extremely high. The core element of success is therefore the reliability, quality, and safety of the equipment, coupled with components that function flawlessly. This applies in particular to the contacts used, including their design and function. Attempting to carry out such work in-house can therefore be a challenge. If, for example, a single crimp connection is to be created, the cost of the required crimping tool (e.g., manual pliers) can amount to several hundred euros. If only small batches or a prototype are required, it is important to weigh up the extent to which the tool costs, additional steps in the production process and employee training for comprehensive expertise in in-house production are worth the considerable financial outlay.

As a system partner, Würth Elektronik eiSos offers a wide range of solutions from a single source. Together with the developer, questions are clarified, such as what is important when choosing the right connection technology and what needs to be considered when assembling cables. Würth Elektronik eiSos offers sound advice and a portfolio of more than 2,000 standard components so that users can implement customer-specific connection solutions. Würth Elektronik offers smaller cable assemblies via its WE service, primarily as IDC crimp connections, and customer-specific printing on the housings. Individualised crimp training courses and free webinars are also offered. It is worth noting that it is possible to borrow Würth hand crimping pliers free of charge to create prototypes or to test the hand pliers extensively before purchasing.

As a system partner, Würth Elektronik has a network of certified cable assemblers known as the "assembly pool". With this unique selling point, Würth Elektronik is setting a milestone: designed for small, medium, and/or large series production, all the assemblers in the network have the tools to ensure the flawless processing of Würth-specific connection technology. Würth Elektronik arranges contact with the assembly partners, adapted to the respective requirements. (Table1).

Complete solution from a single source

The specialised consulting services of Würth Elektronik eiSos during the development and new product introduction phase aim to support the customer in their application to ensure perfect quality and at the same time avoid high rework costs (i.e., in the event of a connector failure). Ultimately, connection technology is an interplay of connectors, connection technology, and cables that is tailored to the respective application.

Picture credits: Würth Elektronik eiSos

The WR-WTB hand crimping pliers with corresponding crimping die are easy to handle and are designed for prototype construction.

The WR-WST IDC hand lever press is available with various mounts (base plates and connectors) for IDC connectors.

With the WR-WTB semi-automatic quick-change crimping tool, taped terminals with open crimp sleeves can be easily processed.

Ready for use: pre-assembled stranded wires with Würth contacts for design-in support.