Technology advancements in recent years have caused an explosion of smart and highly connected computing devices that are in a small form factor. Nearly all of us have encountered some sort of communication device, whether it be in entertainment, health, or lifestyle
Their success has been predicted by human imagination for decades: they helped James Bond 007 when no help was in sight, on Star Trek everyone was using them all the time and the clueless Inspector Gadget was – thanks to them – easily able to run rings around M.A.D agents. Wearables can be everything - from smart clothing to Google Glass to advanced fitness activity trackers to virtual reality (VR) gear to night vision equipment and even heads-up imaging displays. And they are taking over the mainstream consumer, military, and industrial markets.
According to Transparency Market Research (TMR), the Europe wearable technology market is expected to expand with a CAGR of 42.1% from 2014 to 2019, to attain the value of 2.26 bn € by the end of 2019. On the basis of application, the fitness and wellness segment accounted for the larger share in 2012 and is expected to continue its dominance over the forecast period.
But what are the leading design margins? In general, cost; ease of use and the ability for the user to “wear and forget” the device. Therefore it is essential to use miniature size electronic components instead of conventional bulky ones to achieve compact mobile devices with high functionality. However, the lack of internal space makes it challenging to find electrical components that will not only fit but also perform reliably. This difficulty can be particularly noticeable when it comes to board Input Devices and Connectors.
Input Devices - How Your Design Benefits from Switches and Detectors
The feel plays an important role when it comes to controls and can be designed specifically. In terms of the tactile experience attention primarily needs to be paid to the actuation force to be applied to the switch. Every tactile switch has its own unique set of characteristics, which are expressed, in the click ratio (see Figure 1). The click ratio describes the tangible resistance offered by a switch when it is used. The higher the click ratio, the crisper and snappier the switch feels. High-quality switches usually guarantee a service life of 100,000 to 1,000,000 switching cycles, depending on the push force. Like the force/travel ratio, the average service life (switching cycles) for each switch is also specified in its datasheet.Earphones require relatively high click ratios and shorter travel distances (short stroke). This ensures that the operation creates feedback for the user and a sense of quality. Lightweight is another important factor for earphones. As these devices are outside of the user’s direct field of vision and must be able to be operated with a delicate touch a light actuation force is essential. The use of switches with a light actuation force (push force) also rule out any risk of injury. The situation with regard to wearables which are easily accessible and within the user’s direct field of vision is different – here the electromechanical components are set up to reflect a high actuation force (high operation force). Specifically, in the case of smartwatches, the switches are usually activated via the user’s pinch grip strength or even thumb pressure whereby the thumb is pressed against the lower edge of the device whilst the index finger operates the switch. The advantage of such an electromechanical design is that the switch constitutes direct feedback for users and can withstand operating errors such as accidental knocks and bumps better, which is a compelling design feature for wearables in the sports market.
Input Devices - Protection on Account of Patented Laser Welding Process
Tactile switches for wearables also need to be able to work properly in harsh environments over many years. As such, protection against undesirable water, damp, moisture and dust penetration, etc. must also be guaranteed. This has less to do with the water tightness of the device (the construction of the product plays a much bigger role here) and more to do with the fact that the switches also have to be usable for a long time under the same conditions and shouldn’t present any signs of early wear as a result. Such requirements are specified, for example, by the IP67 protection rating for the housings of switches. An adhesively bonded silicone membrane is commonly used for this purpose. However, silicone ages relatively quickly and also loses its elasticity over time. In manufacturing its IP67 tactile switches, Panasonic uses a patented laser welding process (see Figure 2) in which the switch is sealed with a thin nylon film which is applied over the switch actuator. This safeguards the feel of the switch and protects it from developing any signs of wear. An IP67-certified version is particularly advisable for fitness-related wearables as since users keep the devices in their hands, on their feet or on their heads, they are exposed to the body parts that produce the most sweat. It’s not really water but the salt in the sweat that presents the greatest threat to the maintenance-free usage of switches. If you wear a Bluetooth headset when working out, the following issue occurs: the sweat drips down the cable directly into the mechanism which operates the volume control and the microphone – if it is not waterproof in accordance with the IP67 rating, then sweat will get into the switch. After you have finished using the device, what remains is the salt from the sweat which can jam and destroy the switch.
Connectors - How Your Design Benefits from Connectors
Moreover, all of this needs to be presented in a robust, ultra-small electronic design to meet stringent mechanical design requirements for enhanced durability, wearability and comfort of your wearable device. In other words: wearables becoming more and more a design engineering nightmare. More functionality equals more PCBs while the design margin dictates less space and less weight. This is where it becomes useful to talk about connectors.
Micro-miniature connectors require forethought. They demand that designers consider packaging, durability, current-carrying ability, ease of replacement, and other factors early in their designs. It is now possible to source high-density connectors with terminal pitches as tight as 0.2mm and widths down to 1.7mm on the socket side. Just a couple of years ago, connectors with a similar terminal pitch would have been at least 33 percent larger. The increased design requirements also translate into a far more diversified product range. The Panasonic Industry Narrow Pitch Connector Series currently includes more than 3,000 parts which specifically address a number of electrical and mechanical miniaturization issues for both board-to-board and board-to-flexible printed circuit connectors.
Board-to-Board Connectors are used to connect printed circuit boards. Each terminal connects to a separate PCB while connecting the different PCBs without the use of wires. One part, which typically has pins, attaches to one PCB while the part with receptacles is mounted to another PCB. The circuit boards are then connected by mating to two parts of the connector. The advantages are vibration resistance and the prevention of minor misalignments. A further significant benefit in comparison to both labor-intensive and inconsistent hand-soldered connections is that Panasonic Industry’s low-profile, narrow pitch B-to-B connectors are not susceptible to damage from solder rise. And they are available even in a product-range of 4 – 6 pins. Using B-to-B connectors delivers tremendous design advantages in new small and smart mobile device designs – they can be used in applications ranging from hearing aids, through fitness trackers to earphones and save you save manual assembly time, save space by eliminating PCB fixing clips and also make products more reliable and robust.
Connectors - Panasonic Industry's Special Bellows Type
Panasonic Industry narrow-pitch B-to-B connectors feature a rugged contact geometry called “Bellows”. They use advanced materials and contact shape to maximize reliability. Main markets are medical products and wearables due to their miniature size, long life cycle and corrosion resistance against fluids. The robust B-to-B connectors are built around a metal bellows whose spring forces strike a balance between easy insertion and resistance to shock loads (compare Figure 3).
Connectors - Panasonic Industry's Unique V-shaped Notch
The Tough Contact design also features a notched cross-section to ensure a high-force, edge-to-edge contact between connector halves. This V-shaped notch has the side benefit of sealing out contamination from flux or other particulates as well as an integrated nickel solder barrier and a proprietary anti-corrosive treatment. Further benefits of the v-notch structure are increased contact pressure and that it ensures the mating of the contact and contact points.
FFC/FPC: For further information please compare FARNELL
Board-to-Board: For further information please compare FARNELL
Input Devices: For further information please compare: FARNELL
For further product information please compare: PANASONIC
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