Motherboard Design Process

MBRFan writes "MBReview has posted the latest revision of their 'Motherboards - The Designing Process' article. This article covers the design process for modern motherboards, and also goes over some of the most common components that can be found. Definite read for information lovers, though beware, it'll take a while to read!"

Comments

It would have been interesting

[antifoidulus]

if they also gave a little insight into what goes into the manufacturing process as well. After all, you can design the best board there is, but if you have trouble making it in large quantities, it's not going to be successful. Cost and ease of manufacture should be factors in any engineering decision.

Re:It would have been interesting

[bsd4me]

PC motheboards aren't terribly complicated as far as PWBs go. The don't really have a lot of components, and they don't have a lot of layers.

What is interesting about them, but I don't think it really complicates the manufacturing proces, is the effort that goes into reducing the number of layers (number of layers is directly related to cost). This compilcates both routing and signal integrity.

Not bad, but

[jimmyswimmy]

I used to design motherboard power system components, and the author spends a good bit of time talking about that. That is actually the most complicated part of the board design, as it is not at all automated. Most component vendors try to sell a complete solution to the motherboard vendor, easing their job somewhat while helping the sales of the component vendor.

One particularly interesting item of note: all those capacitors the author describes are absolutely crucial, and together form one of the largest cost items on the board. The system is tested using a processor-vendor-supplied "load tool" which simulates the worst case load transients one can ever expect to see. Most of that testing is done by the power system component vendor and then provided as a block to the motherboard vendor. Most motherboard vendors have no idea what they are doing there.

In fact, a lot of the foreign manufacturers (no names) cost-reduce their designs by simply pulling out caps until the system blue screens. Then they put the last one back in and sell it. Intel is the only manufacturer I am aware of that actually sells the worst-case performing design.

Note that I am only aware of products related to Intel-type motherboards. I never worked on the othe stuff.

Re:Not bad, but

[GigsVT]

I guess the question is, will we ever be able to go back to the days when the actual computer power supply did the supplying of power, rather than having a second power supply on the motherboard?

Or are the extremely low voltages and high currents involved with modern CPUs going to always tie us to the motherboard, due to the necessary wires gauges to carry that sort of power at low voltage?

Re:Not bad, but

[Billy69]

Erm, what happens on the mobo is really just a case of regulation, not a separate 'power supply' as such.

And board-level power regulation goes back at least as far as the IBM XT (yup, I had one, they had 7805 5v regulators on them)

But to answer the question I think you are asking, which is why doesn't the PSU supply the processor voltages, you have to think about the number of different processor and interface voltages there have been over the last few years. Processors have gone from using 5v logic supplies down to what, 0.8v now, via dozens of different steps in between. So to supply the voltage direct from the PSU would require either a PSU tied to a specific motherboard which was tied to a specific small group of processors, or a PSU with about 30 different voltage outputs. Both of these options are a lot more complex and painful than just regulating the voltage on the motherboard.

Motherboard design is true art

[Alwin Henseler]

I have always considered motherboards THE most complex, interesting, and difficult part of a computer to design, and design well.

Every single component on a motherboard can be a magnificient piece of work, but it deals only with a limited number of variables. A CPU or chipset component ultimately only deals with bus protocols and internal design. The same goes for other components like memory or harddrives.

But everything comes together through the motherboard, and that (in my eyes) makes it the hardest part of a system to design well, considering the number of variables. A truly well done MB design is really a piece of art.

Yes, but..

[m0RpHeus]

Yes... but does your motherboard manufacturer follow best practices like Feng Shui?

Re:Yes, but..

[vurg]

I think mine does. My northbridge is aligned to the northern dragon constellation, and my southbridge flows with the wind that which cannot be seen.

Re:Maybe someday they could get it right.

[Timesprout]

How does crap like this get modded insightful? There are many factors involved in a production process such as motherboards. In many cases trade offs will have to be made between engineering, manufacturing and cost. If the AC who feels maufacturers are not doing the job properly may I suggest he/she/it puts forward a better design than can be mass produced and afforded by the general population

Doesn't make sense to most people

[Anonymous Coward]

IANAMBD, but...

"trace" == Metal tracks carrying the current

"Prepreg" == insulating "silk" layer separating the metal tracks running above and below.

"static impedance" == "guess" they mean parasitic capacitances formed between the tracks crossing over each other, separated by the "Prepeg".

"Er, or dielectric constant" == See physics book for parallel plate capacitor, the 'E' is the "greek epsilon"

"height of the trace" == the plate separation ... I.e the thickness of the "Prepeg"

.

The guy who wrote this article has a glittering career in the Patent business.

Re:What a terribly written article

[Kehvarl]

Basically what you're saying is...