Seven Design Tips for Smart Appliances
Smart appliances create new challenges for device designers, who must integrate additional components and manage power, data transfer, size, and heat considerations in compact, unobtrusive packages that satisfy consumer demands.
Consumers who value the improved control, energy efficiency, reliability, and convenience of smart home devices are driving the trend toward high-end connected appliances that can communicate with users, each other, and the cloud.
The trend toward smart appliances and the rapid evolution of the various connectivity technologies that allow these devices to wirelessly communicate with the cloud, enable voice activation and remote control, sense and respond to environmental conditions, and share product usage analytics to enhance reliability and reduce service calls is complicating consumer electronics device designs. Smart appliance technologies can now be made to monitor and control water, energy, and heating, ventilation, and air conditioning (HVAC) systems without homeowner interaction, but require extensive electronification in order to do so. Designers developing connected appliances must integrate multiple signal, power, sensor, antenna, motor, and relay components while avoiding the hassles associated with technology “feature creep.”
One way to ease the many design challenges that smart appliances elicit is to collaborate with channel partners who have proven experience integrating multiple functionalities via wire-to-wire, wire-to-board, board-to-system, and system-to-network connections. At a higher strategic level, knowledgeable partners can proactively identify trends and suggest innovative design options aimed at achieving competitive advantages and perfect-fit products for custom applications. Voice of the Customer and Voice of the Industry insights are extremely helpful for establishing a thorough understanding of both current and future requirements and are a critical component of value-added engineering services that can significantly simplify OEM’s design process. Expert perspectives can also help streamline manufacturing workflows by considering high-speed progressive stamping, injection molding, various plating technology, and automated assembly options that can be optimized to meet a wide range of unique product design and manufacturing objectives.
Another way to help ease these design challenges is to consider these seven design tips for smart appliances.
1. General Board-Level and System Design
For general board-level and system design, collaborating with experts is particularly important when facing tighter parameters for handling power and signals. Consumers prefer for connected appliance and other smart home devices to be as small and unobtrusive as possible, which means that all of their internal components need to be proportionally small, and especially so when additional functionality must be packaged into those devices as well. For example, a single occupancy sensor may contain an ambient light sensor, a microphone, and other monitoring elements.
2. Wire-to-Board Signal Conduction
The PCBs in smart appliances tend to be crowded with more sensors and other electronics than in the past. Designers can accommodate more signal lines in less space with 2.5mm (0.098”) centerline and other smaller-pitch connectors. Designers can also employ surface-mount connectors with tight pitches (e.g., 2.5mm and 2.0mm [0.079”]) to avoid the added processing cost of applying through-hole connectors in PCBs with lots of SMT components. Other helpful connector features include terminal position assurance (TPA) mechanisms, which ensure that the contacts are properly seated in the housing and protecting against contact backout; low insertion force, which facilitates assembly; and lanceless contacts, which can prevent snagging and entanglement.
3. Power and Signal Wire-to-Board Connections
Connectors with a tight 2.5mm-pitch are also well suited for power and signal wire-to-board connections and are available in variants with crimp terminations as well as those that meet industry RAST standards for home appliances. Traditionally, RAST connectors are an insulation displacement connector (IDC), which are designed to have the terminal pierce the cable’s insulation during assembly and can save a significant amount of processing time by eliminating the need to cut, strip, and crimp individual cables. Newer signal connectors are also available in smaller pitch sizes designed to better accommodate the termination of discrete wires, ribbon cables, and flexible printed circuits (FPCs).
4. Connecting Power
When connecting power, designers can select larger-pitch connectors for their size advantage, which allows them to accommodate more power lines and higher amperage. Power connector product families frequently offer the versatility of various wire-to-wire and wire-to-board configurations, including vertical or right-angle headers, plus a range of resins to meet UL and other industry standards. Larger pitch connectors can offer higher voltage and current ratings and often include locking mechanisms or other safety features.
For example, TE Connectivity’s Economy Power II connectors with 3.96mm (0.156”) centerlines are rated for up to 600VAC at up to 11A, and its GRACE INERTIA connectors are available with centerlines extending from 3mm to 12.4mm and feature an inertia locking mechanism that simultaneously completes the circuit and locks the connector to protect against vibration. Similarly, TE’s Power Key connectors have a 5mm pitch, an integral key to optimize contact seating and ensure proper mating to the PCB header, and design features that allow the PCB to be potted for environmental protection. Its Power Double Lock connectors are available in wire-to-wire versions with 3.96mm contact centerline spacing and wire-to-board versions with 3.96mm, 6.6mm, and 13.00mm centerline spacing, accept 26–16AWG wire with insulation diameters up to 3.1mm, and are rated for up to 14A per line. They also offer an optional double-lock or, for plug and cap housings, a TPA feature to ensure proper contact alignment and seating and are ideal for use in smart appliances including refrigerators and air conditioners. In addition, TE’s POWER TRIPLE LOCK connectors offer 6.00mm centerlines, ratings up to 20A, and a “make first, break last” (MFBL) safety feature that ensures that the ground is established before the power connection is made and maintained until after the power connection is broken. This series is also glow wire compatible and fulfills several key application requirements for a variety of mid-range power connections, including power cords and power supplies for smart appliances and commercial building equipment.
Along with power connectors, connected appliance designers can also benefit from a wide variety of ring and FASTON quick-connect terminals, as well as crimp splices, which are available in various wire types and sizes to enable properly applied crimps for assured performance.
Designers have a vast and ever-expanding selection of sensor components that are ideal for use in smart appliances, including:
- Temperature sensors, which can include negative temperature coefficient (NTC) thermistors, resistance temperature detectors (RTDs), thermocouples, and thermopiles
- Humidity sensors, which are available as assemblies, components, and PCB modules that are calibrated and amplified to measure relative humidity (RH), dew point, and absolute humidity
- Air and water pressure sensors ranging from basic sensing elements to systems packaged to withstand harsh environments and configured either as board-level components or fully amplified and packaged transducers.
For antennas, standards are proliferating for Bluetooth, Wi-Fi, Zigbee, Z-wave, and other networks. Consequently, designers can work with a broad portfolio of standard and custom antenna technologies, including two-shot molding, stamped metal, FPC, PCB, and laser direct structuring (LDS) solutions, as well as embedded or multi-element external antenna options.
The same types of power and signal connector solutions mentioned above are also relevant for motor connections in smart appliances. Additional considerations include TE Connectivity’s AMPLIVAR terminals and splices, which are especially designed for copper or aluminum magnet wire, as well as its MAG-MATE terminals, which are IDC terminals for magnet wire terminations that are available in styles including poke-in, poke-in tab, splice, crimp wire barrel, solder post, quick connect tab, and pin and receptacle for broad application suitability.
Smart appliances might also integrate relays suitable for energy management systems, household appliances, HVAC controls, lighting, door controls, and home automation.
Giving some though to these seven considerations for smart appliance designs should help narrow the vast selection of component solutions available and help identify an optimal solution. However, given the array of technologies that designers must consider when engineering tomorrow’s increasingly connected appliances, all of which require more power-efficient, compact, and multifunctional solutions, collaborating with trusted industry experts is a sure fire way to ensure that connector and other component products reliably satisfy design goals.
By James Connors, Director, Field Engineering, and Dave Erickson, Field Application Engineer, TE Connectivity