[Milkymist-devel] PCB layout instructions

[Sébastien Bourdeauducq]

Hi,

On Thursday 18 March 2010 08:44:25 Adam Wang wrote:
> All went through done and records [1] on Footprint reviews.

2), 2.2uF(0805)/3.3uF(0805)/4.7uF(0805)/10uF(0805), part --> MLCC; pcb file --
> polarized 0805
6), 100uF(1210), part --> Ceramic chip X5R, pcb file --> polarized 1210

The datasheets say the footprint are 0805/1210. So there should be no problem, 
right?

3), Header(J3, J5), will be given the part number soon, it's popular

For your information, J3 doesn't need to be populated on the production 
devices, it's only meant as an extension for extra audio channels. For this 
reason, we might also not want to populate some parts (R6-R12, C22, R19, C23, 
C25, ...) on the production devices.

J5 is the UART connector. I guess we'll keep it populated as most tinkerers 
will want it. Same for the JTAG connector.

5), C46, voltage rating = 500V? This part is still surveying.

No, the voltage rating is 250V only. These capacitors are for ESD protection, 
and IIRC 250V is the rating required to meet FCC/CE standards. Feel free to 
change this as you have more experience than me with certifications.

The resistors you listed:
http://www.yageo.com/pdf/PYu-RC1206_51_RoHS_L_4.pdf
have a working voltage of 200V only, but an overload voltage of 400V 
(dielectric breaks over 500V) so I think they should be OK.

7), J19, pcb file --> pin1 in wrong position in top side, in correct position 
in bottom side. which side you prefer?

Whatever side. But place the JTAG connector, the UART connector and the SD 
slot (J19) on the same side and close to one another, so that when the board 
is cased we can access all of them with a single door.

10), J8, need confirm on datasheet

What information do you need?

13), J17, footprint will be change to meet datasheet illustration.

Ok. Btw, as you probably know, "MULTICOMP" is a disguised Farnell noname brand 
which may pose sourcing problems. I still went with their part number on my 
BoM because their footprint is fairly standard and other VGA connectors that I 
checked were compatible.

17), L8, part --> 0402 (300mA), this part located in 2V5 power loop; this must 
be wrong, should use like L7 (1210) same part.

True.

I think the other notes are pretty obvious, but if you need comments just ask 
:)

> Some of
> them are not big things just for records like 0805POL, etc. According
> to your bom, pls also see here[2] for quickly & easily review. For
> obvious items in [1] I'll directly change/rebuild footprints for them
> during routing. Meanwhile the parts survey & order are moving on, so a
> Note column listed in [1] to show the compatible parts.

Sounds good!

> Yeah, the DIN(5 ways 45 degrees) datasheet is not 100% clear, so far I
> haven't got those parts. Hope you are right.

If this is of any help, I can ship you a sample or two.

> Now the placement is moving, I'll provide two versions in 2~3 days
> then we discuss. Board size I keep the long side 150mm. The width will
> be changed a little bit.

Ok

Thanks,
Sébastien