High Density Interconnect Solutions
The need for a compact and reliable high frequency interconnect system has spawned a new family of connectors for microwave and high speed digital applications. Southwest Microwave’s family of SSB coaxial connectors features an extremely small pitch with superior high frequency performance. The family is comprised of the SSBP push-on, the SSBT threaded and the SSBB bulleted ultra-miniature connectors. Unique applications for SSBP contacts include use within industry-standard D38999, D-Subminiature, Micro-D and other multi-contact connectors.
The SSB connector family is designed around a common interface with air dielectric and a center conductor captured with high temperature plastic beads. SSB connectors utilize the same materials and construction that Southwest Microwave has used for many years in their other air dielectric connectors.
The air dielectric instead of PTFE provides a lower loss transmission path and allows for greater phase stability in misalignments, vibration and temperature variations.
Superior microwave performance is obtained by using transmission line principles throughout the interconnect system. This includes compensated transitions, high quality plating and proprietary innovations.
The interface shown in Figure 1 displays both the pin (plug) and socket (jack) interfaces. On the left is the pin (plug) end and on the right is the socket (jack) end. On the cable termination ends of SSBP contacts, there are inspection holes so the cable center conductor can be inserted properly. The geometry is based on 0.9 mm connector standards.
The SSBP version is a push-on contact designed to be used in industry standard multi-contact connectors or can be arrayed in a custom envelope for maximum flexibility. The SSBP interface engagement starts with a low insertion force mate. The spring-loaded sleeve is then compressed when the multi-contact connector is fully engaged.
The SSBP interface sides are designated as pin and socket following the convention of the multi-contact connector industry. Standard insertion and extraction tools will work with SSBP contacts. The interfaces are terminated for cable or end launch and compatible with 0.047, 0.086 and other cable types. Multiple contact sizes currently available include 20 and 16, with size 12 in process. Versions are available for industry standard MIL-DTL-38999 (Series I, III and IV), D-Subminiature (MIL-PRF-24308) and Micro-D connectors (special contact arrangements in MIL-PRF-83513 housings). Figure 2 shows a typical multi-pin application in a Micro-D envelope.
The SSBT is the threaded version of the SSB family. It is designed as a replacement to traditional microwave connectors where there are small size or high frequency requirements. The SSBT is available in field replaceable, cabled or adapter configuration.
The SSBT thread is a 2-64 with an outer housing diameter of 0.100 inch. The standard coupling nut has a 0.125" hex. The minimum spacing is 0.250" connector-to-connector (see Figure 3).
The SSBB is the bulleted version for board-to-board or module-to-module stacking applications. The bullet allows for misalignment of connectors while maintaining a good microwave connection. The SSBB has a bullet diameter of 0.060" and is available in several lengths. The smallest length is 0.110" and allows a ±0.012 (total 0.024") axial misalignment. Longer bullets will allow more misalignment. Figure 4 shows a sample of SSBB components. Minimum board-to-board spacing is 0.170" with 0.080" centers.
To electrically evaluate the SSB interface, a pair of SSBP contacts was inserted into a reference two-foot long 0.047 flexible cable assembly with 1.85 mm plug connectors and tested to 65 GHz. The SSBP contacts were installed in D38999 circular connectors for testing. Figure 5 shows baseline cable assembly results (blue line) and then the same cable with the SSBP contact pair included (red line). The difference is the contribution of the SSBP pair.
Applications for the SSB interface include board-to-board and module-to-module connections, multi-contact connector interfaces, multi-line testing uses and blind-mate configurations. The SSB interfaces are ideal for air-frame cabling, test equipment, transceivers, avionics and cabling arrays where high packaging densities and high frequency performance are required.
Southwest Microwave Inc.