LCSC Electronics supplier HCTL introduces how to select the power connector. HCTL outlines the challenges in selecting power connectors that balance increasing power requirements with compact design, emphasizing the importance of understanding rated current, manufacturing processes, assembly methods, and contact point designs to ensure reliable and efficient electronic system performance.
As system designs become increasingly compact, the demand for power supply continues to grow, presenting significant challenges for design engineers. It means that power connectors must accommodate two contradictory requirements: increasing power supply while being designed more compactly. When sifting through the vast array of power connectors on the market, it can be daunting to know where to start. Taking the primary feature of rated current as an example, it contains much to consider.
Power Connector Rated Current
Rated current is the electrical current that causes a specific temperature rise in the female terminal, typically at 20°C or 30°C. To use this data correctly, one must understand the testing methods and consider the testing environment. For instance, some tests are conducted solely on a pair of mating terminals without being housed in an enclosure. Factors affecting the temperature rise of connectors include contact resistance, current flow, and heat dissipation channels. In practical applications, male pins and female terminals are housed within an enclosure, significantly reducing heat dissipation channels. Moreover, since using multiple contact pairs simultaneously, the peak value of the rated current should not be set as the working current for the connector.
Power Connector Manufacturing Process
From a manufacturing perspective, traditional power connectors are mostly machined. The advancement of stamping technology has led to a new generation of power connectors formed by stamping. Compared to machined connectors, the process is simpler, with shorter mold setup times, making it a more flexible production technique. Although the stamping process is more expensive, in mass production, their costs are comparable to machined connectors, especially since stamping technology allows for selective plating, an option not available with machined connectors. From a quality standpoint, stamping ensures a certain level of quality stability in long-term mass production, which is unmatched by machined connectors.
Power Connector Assembly Technology
When discussing assembly, there are various methods for circuit board assembly, such as crimping, surface mounting, or soldering; For cable assembly, methods include screw connections, soldering, winding, crimping, and IDC (commonly known as piercing connections or insulation displacement connections). When choosing a suitable connector, we should not only consider the price. Appropriate assembly technology is also a vital factor.
Soldering connectors are cheaper than surface-mount and crimping connectors because they do not require heat-resistant plastic housings or special crimping areas for the pins. However, if the PCB consists of surface-mounted components, choosing surface-mount power connectors is a more cost-effective choice. For wiring, screw connections, soldering, and winding require manual assembly, while crimping and IDC can utilize assembly equipment available on the market for quick and accurate assembly of connectors and cables. Compared to IDC, IDC has stricter size requirements for cables, and the dimensions and hardness of the conductors and insulation must comply with the specifications of the corresponding IDC connectors to avoid damaging the connectors and ensure ideal electrical connections between the cables and connectors. If used in high-vibration working environments, crimp cable connectors should be chosen. Other factors include working environment temperatures, which may involve whether to use heat-resistant cables.
ERmet Power Module Current Derating Curve
The key design of connectors lies in the contact points formed by the female terminals and male pins. Poor design, manufacturing processes, and unsuitable base materials or plating layers can lead to suboptimal contacts or even the failure to form contact points. Conversely, the excessive clamping force can cause excessive wear on the connector’s plating layer, shortening its mechanical lifespan, i.e., the number of mating cycles.
Contact point designs include machined round pins and terminals, such as European DIN41612 and ERmet 2mm M-type power terminals, stamping-formed double-pin terminals and pins like 2mm HM power modules, SMC connectors, and male-female combined double-pin terminals like MicroStac. Plating materials include gold, palladium, nickel, silver, tin, etc. Silver has high conductivity but is prone to discoloration, especially in sulfur-containing environments. Mild discoloration may only affect appearance, but severe cases can reduce conductivity. Palladium-nickel has high hardness and low porosity, resulting in good corrosion resistance. Gold has high chemical stability, low hardness, and high cost. Each has its advantages and disadvantages.
Stamped Double-rod Terminals
There are two different types of power connectors in terms of configuration. Composite connectors generally have a majority of signal terminals and a minority of power terminals. As for power connectors or power modules, the terminals are all high-current terminals. Traditionally, power connectors are uniquely designed, with each brand being different. In response to the increasingly stringent requirements for power connectors, various standards have gradually included power connectors, leading to the emergence of standard power connectors, such as multiple types of D-Sub, European DIN41612 D, E, F, H, and M-type connectors, 2mm HM M-type connectors and power modules, and ATCA power connectors. Typical examples of composite connectors include M-type European connectors, 2mm HM M-type connectors, and D-Sub connectors.
For example, ERmet 2mm M-type right-angle female connectors offer 55 contacts (5 rows x 11 columns) and have three special contact cavities for placing power terminals or coaxial terminals. These connectors serve individually or combined with other 2mm types such as A, B, C, L, or N types. Conversely, ERmet M-type vertical male connectors have up to 77 contacts (7 rows x 11 columns), with two outer rows (22 contacts) connecting to the shield plate of the female connector. Correspondingly, the male connector also has three special contact cavities for placing power terminals or coaxial terminals. Power module examples include 2mm HM power modules, MicroSpeed power modules, and ATCA power connectors. In addition, there are board-to-wire power connections like MiniBridge and MaxiBridge.
Male and Female Double Rod Terminal
To enable power connectors to provide higher-rated currents, connector manufacturers continuously improve the design of power connectors, including new copper alloy base materials with better conductivity, innovative designs for female terminals and male pin contact points, and enhanced thermal performance of connectors. In conjunction with various working environment conditions, connector manufacturers have also developed a variety of power connectors suitable for high-vibration systems, dustproof and waterproof, with locking mechanisms for special purposes, and even connectors with different colors indicating different mechanical coding to prevent operators from inserting incorrectly. With the increasing automation of PCB assembly processes, tape and reel packaging and pre-installation pick-and-place pads are also becoming more common.
With the rapid development trend of electronic technology, power connector designs will see more breakthroughs in the future. System design engineers will launch higher-quality products with the appropriate power connectors and good PCB design.
Founded in 2012 in Shenzhen, which borders Hong Kong, LCSC Electronics aims to assist engineers and enterprises in purchasing qualified electronic parts for samples and production purposes. After years of continuous effort, LCSC has become a global distributor with an extensive selection of electronic components and more than 4 million registered customers worldwide. LCSC is the distributor of HCTL. Select HCTL’s power connector and other products on LCSC.
