How is my crystal layout looking?

I've done a preliminary layout of my crystals. I've never designed a board with crystals so this is just a rough first pass based on my small set of working knowledge of crystal layout. How am I looking so far? Anything I could be doing better?

Details on the board:

• 4 layer (from the top: signal - ground - split power planes - signal)
• Y1 is 32.768KHz
• Y2 is 12MHz
• load caps are 15pF and 18pF for Y1 and Y2 respectively
• for scale, the space between Y2's pads and the MCU keepout is 1.75mm

Note: this picture doesn't show the MCU power/ground pins. I have them all bypassed with a bevy of 0.001uF, 0.01uF and 0.1uF ceramics on the outside perimeter of the MCU with direct connections to the 3V3 power plane and ground plane through short traces to vias under the chip

EDIT: Updated the crystal layout and picture. I pulled in the crystals towards the MCU and pulled in the load capacitors to the crystals. Even though I'm told it's not important, traces are nearly equal from crystal to MCU. The traces for Y2 are only off by 4 mils if my math is correct. :D

• Looks OK, but you still leave lots of space between the components. C50 and C51 for instance can be placed a full mm closer together, and both crystals closer to the controller. And why did you go in a right angle from C52 to C53? I would cut that corner, and place the via so that it nearly touches the crystal's pad. – stevenvh Sep 19 '12 at 12:50
• Fixed this - updated the picture of the layout. :) – Toby Lawrence Sep 19 '12 at 13:22
• An aside: your vias seem dangerously large, somebody might fall into them :-). Are they 1 mm diameter? I usually work with 0.35 mm vias. – stevenvh Sep 19 '12 at 13:33
• 0.81mm diameter, 0.6mm drill. I just go with whatever Eagle wants to throw me. Rather have big vias and potentially avoid a drill mishit. I haven't had layout problems yet where I'd consider shrinking them to make something work. – Toby Lawrence Sep 19 '12 at 13:55
• Ah, maybe that's what makes them look so large. The 0.81 mm is the annular ring diameter, right? Then you only have 0.1 mm margin. My 0.35 mm vias have a 0.75 mm annular ring, so that's twice as wide. – stevenvh Sep 19 '12 at 15:21

• Y2 is an ABM8G series from ABRACON. 3.2mm x 2.5m x 1.0mm. Here's a datasheet: abracon.com/Resonators/ABM8G.pdf. They are $1.17 -$1.35 a piece at Mouser.. so not terribly expensive given their small footprint. – Toby Lawrence Sep 19 '12 at 14:49