Drill sizes

Updated July 8, 2011

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Note: dimensions below are in inches.

Diameter	Drill Size	Application
0.012	83	Small vias - Do not use unnecessarily
	82
	81
	80
	79
	78
	77
0.020	76	Preferred vias
	75
	74
	73
	72
	71
0.028	70	Integrated Circuits ( DIP ) and TO-92 Small pots signal diodes
	69
	68
0.032	67
0.033	66	Small resistors and capacitors LEDs Headers and small connectors
0.035	65
0.036	64
0.037	63
0.038	62
0.039	61	TO-220 1N4001 Large Resistors
0.040	60	TO-220 1N4001 Large Resistors
0.041	59	Large Capacitors 3A-Rectifiers Small Bridge Rectifiers
0.042	58
0.043	57
0.046	56	Small Terminal Blocks TO-3 and other large semiconductors Small Transformers Relays
0.052	55
0.055	54
0.059	53	10A Terminal Blocks .156" spaced connectors Fuse Holders
0.063	52	10A Terminal Blocks .156" spaced connectors Fuse Holders
0.067	51
0.070	50
0.073	49
0.076	48
0.078	47
0.081	46
0.082	45
0.086	44
0.089	43
0.093	42
0.096	41
0.098	40	Mounting holes for DB-25 type connectors
0.099	39
0.101	38
0.104	37
0.106	36
0.110	35
0.111	34
0.113	33
0.116	32
0.120	31
0.128	30
0.136	29
0.140	28
0.144	27
0.147	26
0.149	25
0.152	24
0.154	23
0.157	22
0.159	21
0.161	20
0.166	19
0.169	18
0.173	17
0.177	16	.
0.180	15
0.182	14
0.185	13
0.189	12
0.191	11
0.193	10
0.196	9
0.199	8
0.201	7
0.204	6
0.205	5
0.209	4
0.213	3
0.221	2
0.228	1

Notes (borrowed from Eddy Electronics in Canada)

Pad and via size: One should maintain the largest practical annular ring to insure a good mechanical, as well as electrical and thermal connection. There is a wide variety of pad sizes and shapes available to accomplish this. Octagonal pads are far superior to round.
Eddy's rule: the pad or via size should be 50% greater in diameter than the diameter of the hole.

Eddy's Inverse: the hole should be 2/3 the diameter of the pad.

Plating through and tolerances: Hole sizes should be specified as finished hole sizes. This compensates for the loss of diameter in plating through the hole; the hole will be around .002" smaller than drilled. This figure represents an average that can vary by as much as 30%. Larger holes will take more plating than small ones as a rule and holes near the outside of a panel will also take more copper. On the other side of the equation, the plating thickness will be greater than the .002" decrease in hole diameter. Due to etch-back and internal stress, you may have as much as .002" copper thickness. This thickness on both sides of the hole adds up to .004" total copper, yet the hole is only .002" smaller.

Obviously, one needs to be careful in considering hole sizes, as there are a great many variables including accuracy of hole location and tolerances within the component to be placed.

A good practice is to allow .005" extra hole diameter to accommodate all of these variables. This also allows de-soldering of defective parts during repair.

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