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Uncommitted and Microbus backplanes are an effective interconnect technology for general purpose small systems.

In multi-card systems, interconnection between the various cards is a critical requirement to address both mechanical and electrical requirements. A backplane is now the recognised optimum technology. Back in the day, connectors would have been positioned as and where required across a frame of some sort, typically a subrack, and the electrical interconnects achieved use wire
wrapping. Not the most efficient of approaches, but one that served well despite the obvious deficiencies in mechanical strength, electrical interconnection and electrical characteristics. The next step, albeit a short-lived approach, was for the connectors to be mounted onto a passive PCB substrate to give improved mechanical properties. The advent of cost-effective multilayer PCB technology enabled the backplane as we know it today to be developed. The venerable DIN41612 connector, specified in open architecture bus structures such as VMEbus, Multibus II and VXIbus, is arguably still the preferred connector for use in general purpose, low speed systems that nevertheless require good signal integrity, mechanical stability and availability in a number of options.

What are they?

Vero Technologies offers two types of backplane: uncommitted and Microbus.

An uncommitted backplane is exactly that. It is a double-sided PCB, supplied as a bare board in widths of 5, 10, 14, 21 and 28 Slots with 96/96 or 96/64 connectors positioned on either a standard 3HP or 4HP pitch. The user is able to define the allocation of the four power planes to rows 1, 2, 31 or 32 as required. Each pin position is bussed across all connector positions and the signal interconnects between the slots can be customised if required by physically interrupting the daisy chain tracks. Guard tracking is provided between adjacent signal lines to reduce crosstalk. The backplanes are supplied without connectors, so cost can be reduced as only the required slot positions need to be populated in the first instance. Press fit or soldered connectors can be used: the press fit versions provide the capability of additional rear connectivity. Power and ground connections are via M3 stud and/or Faston connectors.

Uncommitted Backplane Component SideUncommitted Backplane Solder Side
   
Microbus backplanes are multilayer PCBs. Guard tracking separates signal traces from each other vertically through the board and by tracks tied to Z0 running between the signal traces on each layer. This design feature achieves clean signal transmissions with limited crosstalk from one signal trace to another. The boards accept both standard and reverse format pressfit and soldered connectors, so the backplane can be supplied complete with either the male or female connector on the board. A further refinement is that the user can assemble the backplanes with long tailed connectors in appropriate positions to allow direct access from both the front and the rear of the connector. At the simple product level PCB modules and I/O cables can connect directly to the
connector and the use of longer tails and bridge housings on the rear enables additional permanent connectivity to be added using wrapping, soldering or Vero’s Verowire system.

The Microbus family consists of 5, 10, 15, 21 and 28 Slot widths with 96/96 or 96/64 DIN41612 connectors on either a 3HP or 4HP pitch. All pins are bussed through to the equivalent position on all other connectors; all pins in rows 1 and 32 are dedicated to the ground plane and four other Vcc planes are available. Both power and ground external connections are through M3 stud or Faston connectors. The standard units are supplied with pressfit connectors in all positions with rear shells on the two end slots.

Microbus Backplane Comopnent Side 

 

 

 

 

 

 

 

Microbus Backplane Solder Side

 

 

 

 

 

 

 

 

Uncommitted and microbus backplanes provide a reliable, easily customisable interconnect technology, ideal for developing physical prototypes for multi-board systems. They are easily configured, are low cost and they have an easy expansion and upscale capability. Time to market for new developments is reduced, mechanical and electrical parameters are stable and repeatable and signal integrity is enhanced through the guard tracking design.

In addition to supplying standard uncommitted and microbus backplanes in many different sizes and configurations from stock, Vero can also provide standard units modified to suit a specific application with, for example, only selected slot positions populated with a connector. Fully configured and assembled units can also be supplied and a range of extenders are available to facilitate testing and troubleshooting once the backplane is assembled into a subrack or chassis.

Links to the relevant product pages for backplanes and a range of test extender assemblies is here

To discuss specific requirements, mail sales@verotech.co.uk or call +44 1489 776933.

Ends.