Engineering and Technical Support Group
School of Information Technology & Electrical Engineering

Design Rules > Routing

Protel 99 Path = Design > Rules > Routing

> Clearance Constraint

= 10mil : Preferred (All Objects)

> Routing Via Style

= 50mil dia / 20mil hole  :  Preferred Size

= 30mil dia / 20mil hole :  Minimum Size

> Width Constraint

= minimum 10mil

= preferred 12mil

= maximum user defined

NB: Wider tracks are mechanically superior.  Choose carefully!

Design Rules > Manufacturing

Protel 99 Path = Design > Rules > Manufacturing

> Hole Size Constraint

= minimum 12mil  :  Define hole sizes in 4mil increments

= maximum user defined :  starting at 12mil (0.3mm)

> Minimum Annular Ring

= minimum 10mil  EXTREMELY IMPORTANT!

> Polygon Connect Style

= Rule Attributes

= Conductor Width

= Conductors

= Angle         

= Filter Kind    

= Pwr Plane Clearance

Relief Connect



90 Angle

Whole Board


: Nominal

: Nominal

: Nominal

: Nominal

: Nominal

: Nominal

Design Options > Options

Protel 99 Path = Design > Options > Options

> Grids

= Snap X

= Snap Y

= Component X

= Component Y





: Nominal

: Nominal

: Nominal

: Nominal

> Measurement Unit

= Imperial


: Preferred

Position in Workspace

Place the PCB design such that the lower left corner of the PCB is at workspace coordinate 1000mil, 1000mil.


  • Ensure the PCB border is created on Mechanical Layer 1 using 10mil tracks
  • It is recommended that there is a minimum clearance of 120mil (3mm) between the border and all PCB elements


All printed circuit boards shall be idented on an appropriate layer (Nominally, Top Overlay).  Please note: boards presented for manufacture wihout a suitable ident will be rejected.

Mounting Requirements

  • Do you need mounting holes
  • For M3 mounting holes use PCB library component SPACER01 in KBpcb05 library

Final Checks

  • Ensure you check your schematic running ERC, and PCB by running DRC
  • Further information regarding PCB design requirements may be found at


It is important to note that a large number of PCB footprints intended for through hole components supplied by Protel are incompatible with our manufacturing process.

It is therefore recommended that you use the Electronics Engineering Laboratory Libraries which support many of the components held by this facility and are fully compatible with our PCB manufacturing process.

Schematic and PCB libraries are available for download from the Engineering & Technical Support Group website.

If you have already designed your PCB using (TH) footprints supplied by Protel, it is suggested that you carry out a thorough inspection with respect to physical size, annular ring and hole size requirements for each component before submitting your design for manufacture.

Library Catalogue Access

The Protel Library Catalogue displays the contents of our Schematic and PCB Libraries and is accessible at the following locations:

  1. Electronics Engineering Lab student computing area  >  Non-removable hard copy
  2. Engineering & Technical Support Group website  >  PDF files for download


Please email any suggestions to the Engineering & Technical Support Group Manager