In today's network-centric and data-intensive market, connectors should be a key focus for engineers.
Connectivity is the lifeblood of today's technology-driven world. The term encompasses a wide range of aspects, from references to the internet and data networks to home appliances and devices of all sizes.
As technology continues to advance, the connectivity between any design components becomes increasingly critical. Design engineers may have previously relied on "backup" or favorite connectors for all projects, but the need for increased bandwidth and the elimination of crosstalk or environmental influences has led engineers to seek new, more powerful connectors to optimize their designs and ensure the best possible results.
Connectors have never played such an important role in the success of embedded system design.
The requirements for connector integrity and performance are becoming increasingly stringent.
Before meeting today's high-speed design requirements, the main potential obstacle for connectors is the physical aspects of their design, such as stack height, distance between boards, current requirements, or handling and operating temperature.
As system speeds increase, interconnect design is no longer solely based on mechanical requirements. Now, additional electrical performance considerations must also be taken into account.
Today's designers must consider issues such as crosstalk, skewness, and propagation delay, to name just a few.
Successful connector design requires striking the right balance between maximizing its physical and mechanical strength and optimizing signal integrity.
Connectors are a crucial link in the signal transmission chain and should not be overlooked when designing high-speed systems. In fact, connector design and manufacturing should be part of the overall system-level design process.
Increased bandwidth requirements
The ever-increasing demand for bandwidth has enabled connectors to handle higher data rates across all types of applications. Now, this is not just a need for mission-critical military and aerospace designs, but also for cutting-edge technologies.
It can now be found in all products, from cars to consumer IoT devices.
Today’s rapidly growing bandwidth demands are challenging the ability of traditional design methods to leverage existing technological components.
Although connectors are often considered the “back end” of many product implementations, they need to maintain the same design standards as all other components in any high-speed/high-bandwidth product.
Electrical performance issues to consider
Crosstalk is the unwanted transmission of electrical signals between two or more transmission media due to inductive or capacitive coupling. Crosstalk can also be caused by non-uniformity in the transmission media and skew effects in the signal transmission pair.
At high speeds, circuits generate electrical noise, affecting crosstalk between signals and potentially producing electromagnetic interference noise that can damage other circuits. These realities mean that signal integrity and reliability become extremely important factors.
Historically, crosstalk was attributed to cables, but as LAN speeds and cable quality improved, other channel components began to contribute to improving crosstalk performance.
Connector crosstalk can be a significant problem unless it is permitted in the connector design.
Skew, or propagation delay—intra-pair skew and inter-pair skew describe the difference in propagation delay between electrical signals within a signal pair and between two or more signal pairs in a cable, respectively. Both affect the available bandwidth.
Inward skew causes signal distortion, and the reduced transmission bandwidth results in higher electromagnetic emissions and lower noise immunity. Since, as with most multi-channel data bus systems, all data must be valid simultaneously, inter-pair skew leads to reduced bandwidth.
Both of these issues can be caused by differences in the mechanical length of the signal to the inner conductor or different dielectric constants, and mainly occur in the 90° variant of the connector.
The HSD90° connector has a 2mm base grid, which results in a 4mm length difference between a pair of conductors and implies a time delay difference of approximately 20ps.
Environmental impact—Many of us work indoors under moderate and controlled conditions, so the equipment and appliances around us result in a comfortable but only moderately stressful life.
However, most electrical and electronic systems and machinery that make our lives work smoothly must operate under harsh conditions exposed to natural elements.
If the connector needs to be used in harsh operating environments, design engineers should pay attention to the selection of the connector and check the manufacturer's IP (ingress protection) rating to ensure that it can seal against solid objects and water across a wide range of angles, depths, and operating times.
They should also consider the connector's end-use environment and compare that scenario with the details behind the connector's IP rating. Most IP names have specific criteria, but each manufacturer may define the IP68 rating differently, so when looking for connectors with an IP68 sealing rating, design engineers should make sure to ask the manufacturer exactly how the IP68 rating is measured.
For example, the effect of a system immersed in 2 meters for 24 hours on a connector is different from that of a system immersed for 120 hours for 24 hours, but both cases can be defined as IP68 rating.
Choose the correct connector
When selecting connectors for high-speed performance printed circuit boards (PCBs), it is necessary to evaluate the connectors in their actual use in real-world environments.
Connector data alone can be used to compare the relative performance between two similar connectors, but it may differ significantly from the performance obtained in a real-world application.
Laminate selection is another increasingly important factor in cable and connector design.
Although FR-4 is not the best laminate choice for high-speed/high-bandwidth designs, it remains the preferred choice for many product developers due to its low cost and wide availability.
All connectors need to be both routeable and usable. For example, if a connector requires routing through 16 layers, the design engineer must ensure that the connector used will be designed to support many systems. This is why it is essential to have a thorough understanding of the PCB that the connector connects to, while also considering factors such as design optimization, manufacturability, and final product implementation.
in conclusion
In today's network-centric and data-intensive market, connectors should be a focus of attention and interest for engineers.
Without proper connections, our interconnected world would soon come to a standstill.
Connectors are building blocks for connecting devices and play a crucial role in providing safe and reliable electronic designs for all aspects of our lives.
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