Zhiyong Li

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10 years, 9 months ago.

Is mbed 1768 PCB 2 or 4 layer?

From the following link I realized that mbed 1768 board has passed a EMC test:

https://mbed.org/users/chris/notebook/mbed-emc-testing/

I am curious whether the PCB is two layer or four layer board. Apparently four layer boards have a better chance to pass EMC test but if mbed can get kind of test results with 2 layer design, that could be very encouraging because 2 layer boards are much cheaper to manufacture.

The following link has eagle schematic but no layout file: http://mbed.org/users/mbed_official/code/mbed-HDK/file/bc96cec5b238/NXP/LPC1768

So if someone know the answer please advise,

Thanks in advance. ZL

3 Answers

Martin Smith
10 years, 9 months ago.

I think it is a 6 layer. The main reason why multi-layer PCBs tend to be better at EMC is because they have more complete plane layers (usually middle layers for a 4-layer PCB, or layers 2 & 5 for a 6-layer PCB)

Chris Styles
10 years, 9 months ago.

Martin is correct, it is 6 layer. It could probably squeeze into 4, but 6 is better for EMC for the reasons Martin describes.

The HDK schematics are not routed because the placement, routing, design rules etc, are very specific to each individual design, and if you're going to route a custom PCB, its not that much extra work to route to the subsystem to your own specification.

Hope this helps,

Cheers, Chris

Zhiyong Li
poster
10 years, 9 months ago.

Thanks Martin and Chris.

It seems I underestimated the complexity of mbed board. Luckily my design doesn't have Ethernet-phy, I will see it I can fit everything into a four layer board.

Cheers, ZL