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PCB Layout and Setup Tips 

 

The layout of your PCB project can make an excellent design even better. These are a few simple guidelines, which can be used in your designs.

Measuring Device Leads: are an essential tool in the board design process. When measuring device leads, add a minimum of .010" to the measured size. This will allow for easier insertion of the component into the hole when assembling the board. Care should be taken when measuring square or flat pins, making sure you measure across the diagonal (corner to corner). If using Manufacturer's Specification Sheets, sizes are typically given with +/- variances of the actual pin sizes - again, don't forget to add a minimum of .010".

Drilling Guide: Hole sizes are given as "Finished Dimensions", meaning this is the size of hole desired after all machining and plating of the holes is completed. Using small drill sizes in your design can increase the final cost of producing your boards. Small holes sizes limit the number of boards which can be drilled at production time, can cause more drill breaks, and can impede the plating process. As a general rule, the minimum hole size should be kept at .028".

Pad Sizes: The Annular Ring, known as the pad around a hole, should be at a minimum .010" larger than the hole size and it is recommended to aim for a .020". Leaving too little material on the board can cause problems during the etching process, drill position layout and registration of the film on the board.

Track Width and Spacing Between Tracks: As a general rule, .010" is the minimum space you should design for. Larger sizes give better results and should be used when design opportunities arise. Fine tolerances in tracks or spacing are possible but will cost more when special handling is required.

Component Hole Sizes: Various components require different sizes of holes in order to be placed on your board. The following table illustrates several common components and their associated hole sizes. This information should be taken as guidance only and accurate sizing should be confirmed on your actual components.

 

Drill Size

Component Type

.028''

Fine lead devices such as trim pots and via .holes.

 .035''

 1/4 watt resistors,IC's,small diodes,ripple/filter capacitors,cristal.

 .042''

 T0-220 packages,IDC type square posted headers,1/2 watt resistors,1N9000 series diodes.

 .052''

 Large connectors,wire connections,transformer leads.

 .086''

 T0-220 mounting holes,screw holes,general mounting.

 .125''

 General mounting holes.

 

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