The multilayer planar array is an application specific multi capacitor array designed for use in multi-way EMI filter circuits. Derived from discoidal capacitor theory, it provides capacitance between the outside perimeter and the internal through holes.

The most common use of planar arrays is as the capacitor element in filter connectors, although they are also suitable in many other applications.

Our core wet manufacturing process and ceramic handling expertise allows components to be produced with mechanical precision and electrical accuracy, enabling a filter assembly to withstand the most rigorous of electrical specifications. This has resulted in Knowles Syfer brand's position as the manufacturer of choice for the filter connector industry. To date, Knowles has delivered in excess of 3,000 different designs of planar array.

The quality and reliability of our planar arrays has been uniquely recognised by the approval of NASA for their use in the International Space Station.

With many years of experience, we have developed a comprehensive range of designs, including planform designs for the following connectors:
  • Circular (MIL-C-38999, MIL-C-26482 and similar)
  • Arinc 404 and 600
  • ‘D’ sub
  • High Density ‘D’ sub
  • µD (MIL-C-83513)
Special custom shapes and layouts can also be accommodated. Complex shapes including internal and external radii, multiple hole diameters and alignment guides can be considered.
As a guide, we can manufacture planars to a maximum of 3.18mm (0.125”) thick and to a maximum of 100mm (4.0”) diameter or square.
Standard termination finish is gold plate over nickel for maximum electrical and mechanical performance. 

Solderless assembly/compliant spring clip
Solderless assembly of planars can be accommodated by the inclusion of compliant spring clips into the holes, allowing the array to be push fitted to through contact pins.
We can supply a standard range of solder-in spring clips, or fit customer supplied compliant clips before shipping the finished array assembly.

Contract assembly and technical back-up
Having an EMI filter assembly line alongside the ceramic manufacturing area allows us to offer unprecedented technical back-up and advice to planar array and discoidal customers. This can include design and handling advice and forensic analysis assistance. Our experts have many years of experience in the use of planar arrays, having been involved directly in the development of the technology from its inception. 
We are also able to offer subcontract and prototype manufacturing services to planar customers and connector companies.


  • Only stable X7R and ultra-stable C0G/NP0 dielectrics used
  • Capacitance values from pF to µF
  • High voltage capability - DWV (Dielectric Withstand Voltage) to 10kV
  • Feed-through low capacitance un-terminated lines
  • Grounded earth lines - maximum ground plane resistance specifications included
  • Mix of capacitance values within planar – up to a ratio of 400:1 within individual planar possible
  • Mixed capacitance lines / no cap feed-through lines / grounded earth lines available within single planar

All planars are tested for the following:
  • Capacitance - 100%
  • Dissipation factor - 100%
  • DWV (Dielectric Withstand Voltage) - 100%
  • Insulation resistance - 100%
  • Visual inspection - 100%
  • Sample solderability and dimensional check - 100%
100% SAM (Scanning Acoustic Microscopy) testing is offered as an option on all planars intended for more critical applications.

To reflect the unique custom nature of discoidals and planar arrays, we do not list a standard range, but ask you to contact us to discuss your specific requirement.

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