Gijs WernerAs USB connectors have gained widespread usage in personal electronics equipment, it is necessary that the connectors be small in size as well as rugged and reliable in performance, which has spawned the next-generation microUSB connectors. While the basic design of a USB connector may appear standardized, and the performance/applications may seem obvious, there is enough demand for different versions that manufacturers such as FCI need to offer customers complete families of products to meet those various needs. But designers shouldn’t think that the straightforward design of USB and microUSB connectors means every available connector is interchangeable with all others. There are still a number of considerations to identify and determine before choosing a supplier and specifying a part number.

USBandPWRFirst and foremost, in most cases, the customer should be able to find a standard, off-the-shelf product to fulfill a system’s design parameters. Perhaps the most common mistake design engineers make is insisting on re-inventing the wheel simply to start with something special and to do something different. On the other hand, it’s not simple to design in a component just because it is a proven, commodity part, especially for those engineers not dealing with that component type on a regular basis. Suppliers’ catalogs and web sites offer many different connector types; designers often need to rely on their own experiences or on supplier recommendations to choose the one connector that meets performance requirements and will not be obsolete before the design is finalized. In this way, specifying USB connectors is no different from purchasing another kind of connector or component. A custom solution should be the designer’s last resort, unless it is part of an overall design strategy. (Some customers specifically want custom components to prevent being copied by competitors – but this is rarely an issue with USB connectors.)

The designer should also be flexible in regard to the specifications. Once a design engineer has ensured the performance expectations and physical characteristics of the needed component are within the reach of a connector supplier, he should be willing to compromise if necessary to avoid additional costs. Simple changes to the component requirements can make a big impact on its manufacturing process/cost. For example, specifying a certain plating thickness may be more of a preference than a necessity, but it might make more sense to specify the number of mating cycles required.

From the connector manufacturer’s perspective, they are challenged because many connectors, particularly USB connectors, are being standardized for office environments (PCs, printers, laptops, other similar equipment) but later are adapted for more demanding environments where some specs, like operating and environmental temperatures, are greatly increased. This often requires a change in component materials which could have an effect on manufacturing processes like mold flow and may also impact final dimensions (due to shrinking), pull-out force requirements of pegs or latches, and contact force performance. The challenges in adapting proven products for harsher applications can be avoided if a supplier designs products to comply with more demanding environments from the start.

But that also means that many ‘standard’ connectors will not always function in the harsher environments without some changes. USB, however, is a pretty robust connector, designed for computers but now also popular for industrial, automotive and even medical applications. For automotive applications, manufacturers have found that adding additional latches and, when possible, an additional housing to ‘ seal’ the standard design helps to meet the industry requirements. For industrial applications connector manufacturers pay more attention to true positioning of pins (to support auto assembly) and shield strength. USB is a uniform standard – but still there are lower and higher end products of the same type – like the USB 2.0 type A Receptacle – all within the same approved USB spec. As a designer looking at total applied cost, the higher-priced component from a higher-end supplier may make the most sense for harsher applications in the industrial and automotive markets.

Where the trend is for smaller lightweight end applications, like rugged handheld devices, there is a need for smaller profile connectors; typically they are already being used in consumer applications such as laptops and are now finding their way into more demanding applications. In those cases, many designers are struggling with the standard nylon-based products on pitch of 1.25 mm and 1.00 mm, which do not offer the dimensional stability they are accustomed to with the established systems on pitch of 2.54 / 2.00 mm. This is an area of opportunity for connector manufacturers looking to expand their USB product lines.

USB is a useful standard and one that is actively sought by product designers, but there are still significant differences in the product offerings available from component suppliers. Developments in USB connector technology, particularly toward microUSB connectors which are robust and reliable and allow for many mating cycles, will continue over the next few years to include applications which suppliers and designers may not even have identified yet.