We have a new layout for the A3028 that we believe will allow Matt to 
make a compact and effective mold, while allowing Joyce to load the 
battery without bending the leads at all. The new PCB is part number 
A302801C and the new assembly number will be A3028A2. We made the 
following changes from version B to version C.

(1) Two 60-mil holes allow the battery to load directly, and to sit 47 
mils (1.2 mm) above the top surface of the circuit board. This height 
gives zero clearance on the tallest top-side components. When loaded, 
the battery is centered on the 500-mil (12.7-mm) board.

(2) The corners of the board are rounded with a 75-mil (1.9-mm) radius 
to allow rounded corners in the mold also, making a shape that is easier 
to implant. We would like Matt to try to round the overmold corners.

(3) We replaced the original, unreliable BGA-5 package for U3 with the 
UDFN-6 version of the same part. The new part number is SN74AUP1G80DRY.

(4) We added barrier pads between the amplifier outputs and the analog 
inputs to stop condensation opening a high-resistance feedback path 
between the two. They are the 7 mil wide pads around U5 and U6. These 
pads do not appear in the top and bottom solder paste masks (.GTP and 
GBP files). But they do appear in the top and bottom solder masks (.GTS 
and GBS files). We want these barrier pads to remain gold-plated, so do 
not tin them.

(5) Loading the leads and antenna is the same as before, on the top 
side, except we switched the position of the yellow and red leads. The 
red one is now in the middle and the yellow is on the right, as seen 
from the top side. The blue lead remains on the left. The way they were 
arranged before was a mistake, which we have now corrected. In the 
single-channel version of the circuit, we will clip off the yellow lead, 
leaving only the blue and red leads behind. We want these two remaining 
leads to emerge from encapsulation right next to one another.

(6) Most components have moved around to make way for the new battery 
holes and to keep away from the rounded edges of the board, so here is a 
new spreadsheet with the modified bill of materials and the new pick and 
place positions.

http://www.opensourceinstruments.com/Temporary/A3028A2.xls

Here are the gerber files for the A302801C.

http://www.opensourceinstruments.com/Electronics/A3028/A302801C.zip

Here is the updated circuit diagram, if you're interested.

http://www.opensourceinstruments.com/Electronics/A3028/S3028B_1.gif

And we have new maps for the component locations for you as well.

http://www.opensourceinstruments.com/Electronics/A3028/A302801C_Top_Zoom.png
http://www.opensourceinstruments.com/Electronics/A3028/A302801C_Top.png
http://www.opensourceinstruments.com/Electronics/A3028/A302801C_Bottom_Zoom.png

We submitted multiple versions of the layout to the Advanced Circuits 
Free DFM service. The final version has no problems and is in their 
system under quotation number 3798670 with promotion code DFM100 ($100 
off), name A302801C_V6 (Rev 6). The correct version has date code 
26-MAR-2014 on the bottom silk screen. Plots are at the links below.

https://www.freedfm.com/freedfm/0001776003798670/results/plots.htm
https://www.freedfm.com/freedfm/0001776003798670/FreeDFM-v2.0/freeDFM.pdf

We specified flash gold as the finish for the quotation, but we prefer 
you to specify the finish. We specified flash gold because we thought it 
sounded cool. The quotation is for single boards, not panelized. We 
assume you will have the boards panelized. The board is, as before, only 
0.031" thick.