Global Utilities

La Trobe University
Science, Technology and Engineering

Workshop - Printed Circuit Board Design Guide

NOTE:-

This list contains important links to assist Undergraduate and Master by Coursework students
in their printed circuit board design. For other important issues with pcb design abnd layout contact
the Workshop or the Store during Opening hours.

Workshop requirements for manufacturing of PCBs Guidelines on using Protel
Workshop requirements for submission of PCBs Notes on Surface Mount Devices
PCB Artwork Submission Dates PCB Project setup by Darrell Elton
PCB Requistion Form PCB Design by Darrell Elton
PCB Design and Template Example Workshop Staff members
Clearance and Track width constraints Enquiries for Workshop help

Requirements for manufacturing PCBs

Successful preparation of pcb's within the workshop facilities requires certain design criteria to be met.
This design critera also applies out in industry and it would be helpful now that you could get into the practice of designing an efficient and reliable pcb that should work without any major problems. - As they say "Practice makes perfect!"

In summary the most important features of a successful design which are frequently overlooked are:

  1. Tracks must be a minimum of 0.3mm (12mil) wide.
  2. Track separations must be a minimum of 0.3mm (12mil).
  3. Pads should leave a minimum 0.3mm (12mil) annular ring around any hole. Therefore if your device requires holes of diameter 1mm (40mil) to accommodate the pins, you will need the pads to have a diameter of at least 1.77mm (70mil).
  4. For Dual in line packages - (DIP's), pads recommended to be formed as an oval shape with the X-size co-ordinate being a minimum 2.54mm (100mil) and Y-size co-ordinate being a minimum 1.27mm (50mil). This allows for easy drilling, assembly and soldering of the Dual in-line package to the finished printed circuit board. Also tracks can be easily routed through a DIP device if the pads are formed/created in this manner.
  5. Notice also that the Departmental pcb process does not allow plated-through holes. Therefore any connection between the two board sides must be made by soldering vias between top and bottom. If you apply auto-router, it may generate a large number of vias which would need to be manually soldered. For packages with footprints which overhang the package pins (and therefore cannot be soldered directly on bothsides of the board), room must be left near to the package to allow lines on the package to connect through vias to the board underside.
  6. With surface mount devices (SMT) we prefer that the 1206 footprint (ie: capacitors and resistors ) be used in most surface mount design layouts here at La Trobe. This is because the 1206 footprint is easier for the workshop to manufacture your pcb with the current pcb manufacturing processes we have in place. Also the 1206 footprint allows for easier construction of your project, as the devices are much easier to solder too and allows easier access for testing purposes. But if your design requires the need to incorporate smaller SMT devices, we only stock in our workhop stores the devices that have the following 0805 and 0603 footprints, contact workshop for more details.

 

 

Requirements for submission of PCBs

Here is a set of criteria for submitting your pcb to be manufactured by the workshop.

  1. Submit your PCB using the PCB REQUISTION FORM .

     

    Note:-

    • Clearly label your Name and Student Number. File's name, location, description of the board and quantity required.
    • PCB REQUISTION FORM and artwork must be checked and signed by your Supervisor before submitting the form to the Workshop.
    • PCB layout files will be submitted by Email to Workshop_ee@latrobe.edu.au.
    • PCB layout files must be submitted as a individual file (eg. Filename.PcbDoc) or preferably labelled in your name (eg. JohnCitizen.PcbDoc) and not as an entire Protel Database (eg. Filename.ddb) or Altium Project (eg. Filename.prjPCB).
    • Printouts must be supplied with PCB Requistion Form. (ie: Component overlay, Bottom and Top Layer).
    • PCB Artwork is only accepted if presented on PCB Templates as given below. (see - Item 10 .)
    • To avoid delays in manufacture please ensure that your pcb layout follows these design rules. If your layout does not follow the design rules or is unnecessarily wasteful of pcb space the workshop will reject your artwork. If your artwork is rejected you will have to make appropriate changes before it will be manufactured and you may have to wait for the next scheduled pcb production run.
    • If you have any concerns or problems with the above or any guidelines on this page. Please feel free to consult any workshop staff member or Email at workshop_ee@latrobe.edu.au .
  2. Files must be layed out using Protel for Windows Version 2.8 to Altium DXP.
  3. Component overlay must be provided in pcb file.
  4. Board to be initialled and dated on at least one copper layer.
  5. A minimum track width of 0.3mm (12 mil) must be observed.
  6. Track and pad clearances must be 0.3mm (12 mil) minimum.
  7. Strings or Component Text must be 1.0mm (40mil) minimum height.
  8. Bottom layer strings must be mirror imaged. This is because the bottom layer is viewed from above during layout but can only be viewed from below after manufacture.
  9. Keepout layer must be used where applicable. Why? To enable the Workshop staff too have a guideline to cut the board to a specific size that you requested. The Keepout outline should be preferably drawn in the Keepout Layer (Pink) but we will except it on the Bottom Layer (Blue) or Top Layer (Red).

  10. TEMPLATES
    The workshop will only accept pcb artwork if it is presented on one of these templates when submitting in your pcb artwork for production. These layouts can be saved into your student account, then imported into your Protel/Altium project database. You can then load your Netlist into this template and begin your layout.

    (Click on links below to download workshop PCB templates.)
    240mm by 140mm 140mm by 115mm 140mm by 90mm
    90mm by 65mm 65mm by 40mm  
  11. All tracks, pads etc. must clear outer perimeter of board by 5mm (197mil) minimum. Photoresist is not reliable in the 5mm (197mil) margin.
  12. Finished hole size must allow a 0.3mm (12 mil) anular ring on the component pad.
  13. For SMT designs we prefer you to use the 1206 package/footprint during your project here at La Trobe. Specifically when placing resistors and capacitors, we prefer them to be in the 1206 footprint format. (See Surface Device Information)

Please visit the Workshop's Clearance and Track width webpage for more information in aiding you to better layout your Printed Circuit board.

 

Workshop Help

If you have any concerns or problems with the above or any guidelines on this page. Please feel free to make an appointment to consult any workshop staff member for help or questions on your PCB design. Or Email the appropriate Workshop staff member that you wish to seek help or information from.

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PCB Design and Template Example

This example shows a PCB for a simple logic circuit and power supply. You will draw a schematic, and layout during your final year and third year project.

It uses a single sided board (all tracks and pads on the bottom layer) and has a component overlay on the top of the board.

All power tracks are 100mil/50mil except for small signal tracks length of 25mil/12mil track connecting the transistors and IC. Note that all I/O connectors are grouped together on one side of the board, and the components are nicely spaced apart.

We would like your PCB to be presented to workshop for manufacture using a similar guideline template as in the image below. With title information filled in blue on the top.


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