photo credit: ifixit

You can tell a lot about the engineering culture of a company by peering under the hood of their products. Let’s take a look at the motherboards of some recent tablets by three major players. First, here’s the second generation Nexus 7 tablet by Google and Asus.

(Image from ifixit)

(Image from ifixit)

This board is pretty compact. Standard green soldermask is used (which may reduce cost by a tiny amount) and there are some test points for a bed of nails test jig. If you look on the right of the bottom image, you can see a footprint of a part that’s not populated. It may be left over from testing. There are several markings to help track the board, both in silkscreen (top left of bottom image), ink stamps (top right of bottom image) and a sticker (top image). It’s clear that thought went into this design and an effort was made to keep it small, although nothing too extreme was done. This is probably a 4 or 6 layer board.

Let’s look at another one: the iPad Air by Apple.

(Image from ifixit)

(Image from ifixit)

This board is extremely compact, and I think, quite beautiful. Matte black soldermask has always been my favorite. Chips are right next to each other, and there’s almost no empty board space on top. There are only two markings on the board, both in silkscreen on the bottom. The bottom is also mostly devoid of components, except for filter caps. There are also a huge number of bed of nails test points. The sacrifice they made for being able to have all the chips so close is the number of layers. This is a 10 layer board, which is more expensive. They also use 3D chip stacking, and complicated and expensive techniques for inter-layer routing. Here’s what the cross section of an iPhone 4 looks like (similar techniques are used in the iPad Air):

This is an intricate design. The culture here seems to be one of detail and care. They’re willing to pay more money (because their customers are willing to pay more money) to get this thing as small as possible, even if the actual layout it more complicated. It all goes back to aesthetics. That’s what’s most important here. How can we make the device as small and thin as possible? The use of black matte soldermask matches all the internal colors as well, showing another layer of attention to appearance, even if almost no one will ever see it.

That’s hot. (Image from ifixit)

Disclaimer: I don’t own any Apple products, and I don’t agree with how closed their ecosystem is, but I sure do admire their design.

Last one: The Surface Pro 2 from Microsoft.

(Image from ifixit)

(Image from ifixit)

I think that speaks for itself.