[1] http://oshpark.com/guidelines
[2] http://blog.oshpark.com/kb/4-layer-stackup
[3] http://oshpark.com/LaenPCBOrder.dru
[4] http://batchpcb.oshpark.com


                   |Dorkbot|Dorkbot|    --- oshpark ---    | -- batchpcb - |blog & |
                   |PBX  2L|PBX  4L| 2L[1] | 4L[2] | dru[3]| 2L[4] | 4L[4] |twitter|
-------------------+-------+-------+-------+-------+-------+-------+-------+-------+
Min. Trace Width   |   6mil|   6mil|   6mil|   ?   |   6mil|   6mil|   5mil|       |
Min. Spacing       |   6mil|   6mil|   6mil|   ?   |   6mil|   6mil|   5mil|       |
Edge Clearance     |  15mil|  15mil|  15mil|   ?   |  15mil|    ?  |    ?  |       |
Min. Drill Size    |  13mil|  13mil|  13mil|   ?   |  13mil|  12mil|  10mil|       |
Min. Annular Ring  |   7mil|   7mil|   7mil|   ?   |   7mil|   6mil|   4mil|       |
-------------------+-------+-------+-------+-------+-------+-------+-------+-------+
Copper Top         |       |       |   ?   | 1.4mil| 1.4mil|       |       |       |
Prepreg            |       |       |   -   | 6.7mil|   -   |       |       |       |
Copper 1           |       |       |   -   | 0.7mil|   -   |       |       |       |
Core               |       |       |   ?   |  47mil|  59mil|       |       |60.2mil|
Copper 2           |       |       |   -   | 0.7mil|   -   |       |       |       |
Prepreg            |       |       |   -   | 6.7mil|   -   |       |       |       |
Copper Bottom      |       |       |   ?   | 1.4mil| 1.4mil|       |       |       |
-------------------+-------+-------+-------+-------+-------+-------+-------+-------+
Cutouts            | 100mil| 100mil|   ?   |   ?   |   ?   |   ?   |   ?   |  35mil|
Largest Hole       | 260mil| 260mil|   ?   |   ?   |   ?   |   ?   |   ?   | 265mil|


Min. Board Size    | 0.25 x 0.25"
Max. Board Size    | 16.5 x 22.5"
Silkscreen         | 200dpi