How to choose the correct and suitable circular connector | MOCO connector

September 20, 2022

Connectors play a key role in almost every product we can imagine, affecting their overall performance and reliability. However, interconnect requirements are usually only considered at the end of the product design phase. It is only when a poorly manufactured or misspecified connector fails that the impact of interconnect selection usually becomes very clear, at least eroding system performance or even causing the system to stop functioning. Fortunately for designers, advances in connector design, materials and manufacturing ensure that interconnect solutions that are perfectly matched to each individual application are easily obtained.

Selecting the appropriate connector depends on the performance requirements of the design, configuration constraints, operating conditions and operating environment. As a result, connector requirements for healthcare products are quite different from those for deep mining applications - but both require maximum reliability from connectors.

From transportation control systems to sensor-connected communication systems, circular connectors provide a rugged, waterproof cable-to-panel/PC board interface for demanding end-use applications. Engineers continue to design these industry-standard connectors because of their robust design and space-saving compact geometry. Contact-to-contact circular connectors take up less space than rectangular connectors, enabling efficient use of mounting connection space for a variety of design applications.

Circular connectors come in a variety of materials, sizes, styles, contact arrangements and designs, each size offering a unique solution.

Selecting the correct circular connector for your application can be a challenging process as it can be difficult to differentiate between the various options.

Without proper consideration of connector selection, the entire application can face performance and reliability failures. In fact, today's innovative connectors are high precision components, meticulously designed and manufactured using a variety of highly conductive alloys, application specific plating and high temperature, high strength housing materials.

The socket itself is a product of precision machined and specialized alloys designed to meet specific application requirements. For precision connector production lines, high-speed Swiss turning and CNC machining can produce parts of various sizes while maintaining a very tight diameter tolerance of ±0.0005" - even tighter for some applications! Internally stamped finger contacts are available in diameters from 0.008" Connections are provided to 0.102" mating leads and square and rectangular pins.

Using advanced processing capabilities, interconnect manufacturers can offer receptacles with a variety of termination styles, including crimp, solder mount, compliance crimp, swage mount, and wire termination options, including solder cup, crimp, bifurcated and forks. These same manufacturing capabilities allow the creation of specialized sockets suitable for pressing into plated through holes of printed circuit boards. Here, polygonal press-fit features such as squares, hexagons, pentagons or octagons are machined into the body or tail of the socket - providing stress relief when pressed into plated through holes on the PCB. The crimp function is typically maintained within a tolerance of ±0.0005 inches to help maintain consistency during the crimp operation, which is especially important if the application requires a solderless crimp.

While precision manufacturing allows for a variety of shapes and sizes, the materials used for interconnect fabrication impart specific performance and manufacturability characteristics to these components, optimized for different application requirements. In the fabrication of machined electrical interconnects, a variety of alloys are used—mostly copper-based alloys because of the need for high electrical conductivity—from highly ductile brass to high-strength beryllium alloys.

Brass is the most commonly used because it has excellent machinability, is suitable for a variety of applications, and is cost-effective. Phosphor bronze is a more ductile material and is useful when additional strength and flexural resilience are required. For higher current applications, the high conductivity (93% IACS at 68°F) of copper telluride provides a low resistance electrical path resulting in less temperature rise.

Depending on the size and force characteristics required, the internal contacts are available in three-, four- or six-finger designs and are stamped from beryllium copper alloy C17200 (HT) or beryllium nickel alloy 360. Beryllium copper has become the standard for most people in a wide variety of applications due to its excellent strength, spring properties, durability and electrical conductivity. Beryllium nickel has similar properties and is especially suitable for high temperature environments above 150°C.

Application requirements

State-of-the-art connector technology offers options designed to meet specific performance and configuration requirements in a variety of applications including healthcare, LED lighting, and harsh environments. More specifically, the combination of precision machined housing and stamped internal finger contacts provides the flexibility, quality and reliability required for mission-critical applications.

For example, in the healthcare industry, high-reliability sockets are used in several places: detector boards for CT scanning equipment; I/O connectors for portable blood analyzers and implantable devices; for monitoring and regulating life Sensors for signs, blood sugar, and other bodily functions; in signaling circuits for drug delivery pumps; as power jacks for medical and dental drills and saws; and cables for a variety of medical devices and devices.

Pins and sockets are often the building blocks of these interconnect systems. Typical healthcare interconnect applications require fine-gauge wires to be terminated to male and female assemblies to form cable assemblies. One solution Mill-Max designs and provides is precision machined pins and sockets with wire termination options such as solder cups or crimp barrels. The sockets feature high-reliability beryllium copper spring contacts that make safe electrical and mechanical contact with mating pins. All components are gold plated for protection, durability and reliability

Interconnect flexibility

In more advanced interconnect systems, beryllium nickel contacts are housed in the same socket housing as their beryllium copper counterparts and can be specified as the design evolves from the bench to the field. In fact, this configuration flexibility is increasingly important to designers. With more complex interconnect solutions, engineers can test their interconnect designs, modify interconnect strategies, and even switch to different connector materials and sizes without having to redesign the overall interconnect design.

For applications requiring optimum environmental protection or for PCB crimping applications, gold plated housings and contacts are often the right choice. If the housing and internal contacts are individually plated in an interconnect system, the design engineer has the flexibility to choose tin, tin/lead, gold, or silver plating based on economic and engineering considerations. For example, tin-plated or tin/lead-plated housings with gold-plated internal contacts are a cost-effective option for solder-mount sockets that accept gold-plated matching leads. Despite the different combination of metals, the hermetic press fit between the contacts and housing eliminates the chance for oxidative interactions.

In addition, a well-designed interconnect platform allows designers to vary pin sizes by building in a wide matching lead acceptance range. While some interconnect systems have a fairly tight 0.004" lead acceptance range, enhanced interconnect contacts have a larger reach, typically 0.010" and larger contacts up to 0.020" in some cases . The wide acceptance of receptacles translates into greater tolerances in mating lead size and location—a useful option when devices, mating boards, modules, or cables unexpectedly change in pin design or gauge. So if a piece of equipment was originally designed to accept a specific size cable, and that cable is modified to use larger or smaller pins,

The flexible interconnect platform also allows engineers to select higher or lower force contacts for most matching lead sizes. For applications such as high pin count interconnects, lower forces are required; delicate, soft or flexible leads or wires; insertion into leaded glass sealed (sealed) devices; and easy field replacement and repair in tight spaces. Conversely, higher forces are required for rugged applications that face high shock and vibration, fretting corrosion, high current connections, and long-term static connections. Additionally, higher strength connectors can help overcome oxides caused by environmental conditions, especially beneficial in low current circuits.

If you're not sure which connector you should choose for your application, get in touch with us today to speak with one of our engineers and get expert guidance in your decision-making process.

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