PHOTO FABRICATORS, INC.

Suggested Production Parameters

DATA FORMATS:    (back to the top)

When designing CAD data for Gerber output, it is important to keep the following in mind:

If any files need to be merged, please have them merged before sending the files for production if possible to avoid any human error. Also, all pads should be flash as opposed to draw data. This serves to minimize file size, reducing computer processing time and allows us to extract net list information for electrical test. If drawn data is supplied, we must convert it which again leads to the potential for human error. Create polygon fills ,i.e. plane areas, using the largest aperture possible to provide the required resolution. Do not use a cross hatch fill pattern when producing a solid fill, and do not overlap fill segments by more than 1mil. Failing to observe this will create exceedingly large files. We have received files which, after the step and repeat process, are so large that they require an entire shift just to photo-plot.

 

LINE WIDTH:    (back to the top)

Standard line widths are 8 mil. (.008) or wider for signal traces.
Cost increases below 8 mils (7 mil. [.007] to 5 mil. [.005] lines are possible).

 

HOLE SIZE:    (back to the top)

Standard hole sizes are 250 mil. (.250) to 20 mil. (.020).
Any hole larger than this, including plated slots larger than 100 mil (.100) must be NC-Routed which adds an extra step to the drilling process. Therefore the price is affected for any non-standard holes.

 

PAD SIZE:    (back to the top)

On External Layers, pads should be at least 20 mil. (.020) larger than the hole size.

 

CLEARANCE ON POWER AND GROUND PLANES:    (back to the top)

The clearances should be swelled to 40 mil. (.040) larger than the hole size.
Mounting holes or non-plated holes also need a clearance to keep the power and ground planes from shorting together. If the mounting holes are grounded they will need a thermal on the ground plane and a clearance on the power plane.

 

THERMALS ON POWER AND GROUND PLANES:    (back to the top)

Thermals or Heat Reliefs should be at least 20 mil (.020) larger than the hole size.
Example: A 40 mil. (.040) hole should have a 60 mil. (.060) pad with at least an 8 mil. (.008) web.

 

AIR GAP:    (back to the top)

(Distance between line/line and line/pad and pad/pad)
This should be at least 6 mil. (.006) depending on customer’s electrical requirements.

 

SOLDER MASK:    (back to the top)

Swell solder mask 13 mil (.013) larger than the Pad, SMT or Non-Plated hole size.
If LPI (liquid photo image-able) solder mask is required swell to 5 mil (.005).

 

SILKSCREEN: (Nomenclature, Legend)    (back to the top)

All component designations should be drawn with at least an 8 mil (.008) stroke width. It the lines are thinner they will be illegible on the finished circuit board. Legend ink should stay clear of surface mount pads, component holes and Non-Plated holes.

 

FABRICATION DRAWING:    (back to the top)

This drawing may be supplied in either Gerber, HPGL, DXF or hard copy form. This drawing will be used as a reference during the manufacturing process and should provide the following information:

1. Dimensions for the board profile, and location of at least one hole relative to the corner of the board.
    

2. Drill hole locations along with a hole chart and should clearly identify any un-plated holes.
    

3. Size and location of special cut outs, slots and/or routing requirements.
    

4. Type of solder mask required.
    

5. Thickness of copper required on inner and outer layers.
    

6. Thickness and type of material required.
    

7. Indicate number of layers, as well as layer stackup.
    

8. If U.L. approval is required, clearly show the logo location on the pcb and whether it should be in the etch or part of the silkscreen.