AP Circuits is capable of drilling in any number of drill sizes down to 0.013" finished. However, we can keep our costs down (in terms of setup time) by providing a pre-selected set of drill sizes. Costs we save are then passed on to our customers. For this reason we provide a group of common drill sizes for you to choose from:
If your project requires drill sizes not outlined above there will be an extra charge for each additional size.
Guidelines - Drilling
Over sizing of a pin by .010" is a generous measurement and will include the plating factor. Hole sizes in a plated through hole board reduce by .003" to .005" from the drilled size.
Designs requiring hole locations guaranteed non-conductive must use our affordable post-process drilling option.
For non-critical locations you can attempt a process known as "tenting". "Tenting" uses process film to dam both sides of a drilled hole. This may prevent chemistry from entering and plating but there is no way guarantee success. You can improve your chances of a non-plated location if you ensure that both sides of the board meet these minimum requirements:
Features include ground planes, any pad or trace, board edges, slots, notches, other holes. There is no "tenting" fee as non-plated results are not guaranteed.
Providing us with any of the following:
Will automatically result in premium-fee post-process drilling.
The .042" is a very versatile size for prototyping. It's finished size (.039") is a bit too sloppy for machine assembly (IC's and resistors), but it's great for hand assembly.
In many cases you could use .028, .035 and .042 for most of the board's IC and related "glue" hardware. The larger diameters will come into play for interconnects, transformers and mounting hardware etc.
It is best that you never "guess" when it comes to the size of the required hole. Instead use calipers to measure the devices you intend to use.
Note: Some component leads are very delicate. Be careful you don't twist them out of shape. It may be necessary to relax the caliper's grip when rotating the lead.
Example: If a dual-row ribbon cable header uses a .100" space from pin center to pin center and is square posted, then the actual measurement (cross corner) will be in the .032" to .036" range. Adding .005" to .010" would suggest that you may want to drill it at .039" to .046". Ideally, you also want to maintain a minimum .010" annulus on the pad after it's drilled (improves solderability), this would then indicate that you should use a .061" to .066" pad.
A device that has a symmetrical square post can use the following calculation:
For example, the following calculation will be required to provide the absolute minimum diameter of a "finished hole" for a .025" square post:
High Density Drilling (HDD):
Boards with an average of more than 24 holes per square inch are subject to a high density drilling premium of $0.01 per hole per square inch to compensate for additional drilling time.
Example: an order of 2 4"x5" boards with 600 holes