We are well aware that with each iteration and upgrade of electronic system architecture, the data transmission rate will increase accordingly; In an environment where integration continues to improve, high-speed clocks and multi bit modulation techniques work closely adjacent to the power bus. Managing circuit interconnections in this environment requires us to make every effort to ensure signal integrity, minimize transmission losses, reduce sensitivity to noise, reflection, and crosstalk, and meet the bit error rate (BER) requirements of modern data buses.
Multi pin connectors are a key area of concern for many people and a focus on improving signal integrity. A multi pin layout that combines differential, single ended, and power signals requires careful layout and considerable flexibility. In addition, the design of connector contacts should ensure their compatibility with high-speed data rates and have a longer contact life.
Samtec is a manufacturer of a full range of electronic interconnect solutions and has expanded its product line of high-density AcceleRate HD array connectors (see Figure 1) to address the various challenges mentioned above.
Figure 1: The figure shows a pair of male/female AcceleRate HD open field array connectors, designed specifically for high-speed transmission rates and frequent plugging and unplugging. (Image source: Samtec)
This series of connectors adopts an ultra dense multi column design, with a spacing of only 0.635 mm (0.025 in.) and a width of 5 mm (0.197 in.). This series adopts an open field array design, which can achieve the highest layout flexibility, and the Edge Rate contacts of this connector can achieve high signal integrity and low insertion loss, suitable for bus speeds of 64 to 112 gigabits per second (Gbits/s) and frequent plugging and unplugging operations.
The cceleRate HD array connector has a single row of selectable contacts ranging from 10 to 100, with each row configured in multiples of 10. It can accommodate up to four rows of contacts, with a total contact point range of 40 to 400.
For example, ADM6-100-08.5-L-4-0-A-TR is a male connector in a set of 400 bit array connectors, while ADF6-100-07.5-L-4-0-A-TR is a female connector. These connectors are used for surface mount installation of printed circuit boards (PC boards). In sandwich applications, the daughter board is installed above the PC board, and the installation heights supported by the compatible lead styles of the sandwich application include 5mm, 7mm, 9mm, 10mm, 11mm, 12mm, 14mm, and 16mm mm (0.197 in., 0.276 in., 0.354 in., 0.394 in., 0.433 in., 0.472 in., 0.551 in. And 0.630 in. can meet the required installation clearance requirements.
Advantages of needle opening field array
The performance of connector contacts is not solely determined by their design. The physical arrangement of contacts and their relative position to other contacts are factors that affect performance. For example, using large cross-sectional pins to transmit power can cause the aforementioned mutual effects; High current requires a larger pin diameter, but this reduces the distance between contacts, thereby limiting the maximum voltage that can be used. Another method is to use a needle opening field array, where each pin position is available without preset functionality (Figure 2). With the design of a needle opening field array, differential pairs, single ended signals, and power supplies can be used through the same interconnect device, greatly improving the flexibility of grounding and wiring.
Figure 2: The pin positions of the needle opening field array connector are independent and can be allocated as needed during the design process. (Image source: Samtec)
Pin allocation may vary; Differential signals may be paired and connected using adjacent pins, with the middle pin left blank to provide isolation between conductors, as shown in the green section. Single ended wires can be assigned to individual pins, with or without intermediate isolation pins, as shown in the blue section. Power connections that require larger conductor diameters can be achieved by parallel connection of multiple pins, as shown in the red section.
Design of Edge Rate Contact Point
Samtec's AcceleRate HD connectors, including ADM6-100-08.5-L-4-0-A-TR and ADF6-100-07.5-L-4-0-A-TR connectors, combine high signal density and mechanical flexibility, with enhanced signal integrity, supporting signal transmission at up to 64 Gbit/s PAM4 rates, and compatible with PCIe ® 6.0/CXL ® 3.2. The design difficulty of PAM4 signal is relatively high because it uses four voltage levels, while traditional non return to zero (NRZ) signals use two levels. This will reduce the signal amplitude variation by one-third, making signal-to-noise ratio (SNR) an important focus.
Samtec has overcome this technical challenge by achieving excellent signal integrity through its advanced Edge Rate contact system (Figure 3). The characteristic of this system is that the contact surface is milled, which can achieve smooth insertion, less wear, and stronger toughness, making it suitable for applications with frequent insertion.
Figure 3: Edge Rate pins are milled to reduce wear and ensure low resistance connections. (Image source: Samtec, author's note)
The AcceleRate HD connector adopts a process of copper substrate, nickel plating as the base, and gold plating on the surface. The geometric shape of Edge Rate contacts can accurately adapt to interconnect impedance requirements of 50 ohms and 100 ohms (Ω). By arranging the thin cut edges of the contacts facing each other, it is possible to minimize wide edge coupling and crosstalk to the greatest extent possible.