Why don't console manufacturers use PGA for their CPUs?

[Joseph F]

I know that price is the primary reason, but in the long run wouldn't they save money by using PGA to attach their CPUs to the motherboards and not having the interconnects break like they do with BGA? The way I see it is that it would probably cost a few extra dollars per board to use PGA rather than BGA but since PGA never fails it would save them millions because they won't have to replace ~50% of their console with refurbished ones. (Looking at you, M$)

 

[PlasmaBomb]

Off the top of my head - size, packaging, cost

There are articles which deal with the advantages -

Wiki

Siliconfareast

 

[A5]

Almost no high-end electronics use pass-through mounting anymore due to packaging reasons. PGA makes it much harder to hit the high pin densities required these days.

The problem with the 360 was bad thermal management causing the solder to melt - using PGA wouldn't have helped that any.

 

[sm625]

There is no reason BGA connections should break, aside from thermal issues. Some game consoles (and notebooks) simply ran too hot for consumer devices. The key is the difference between realworld airflow, and that which they specify in the fine print. Once you use a device for any length of time, it collects dust, which the consumer is responsible for clearing regularly. But of course most dont do that.

The consumer should have said "no thanks... maybe I'll buy the wii because it doesnt produce more heat than can be safely dissipated, especially once the system gets a healthy coating of dust!" Yeah I can just see the average consumer thinking like that. But nonetheless that would have been the correct decision. Nowadays, after several die shrinks, all the consoles should run cool enough to where cracking bga solder joints should not be a problem. However yes there is still the flexure problem. If the pc board gets bent (somehow) then that greatly increases the chance of cracking. The best thing to do to prevent that is to simply uses a bigger package, with large balls biggrin and not focus so much on having this cute compact little thing. Just give us something that works ffs. But of course we all know the console makers couldnt give a damn about us... at least not microsoft and sony. Nintendo is pretty cool. They replaced a brand new but completey shattered DSi for $60.

 

[sm625]

Almost no high-end electronics use pass-through mounting anymore due to packaging reasons. PGA makes it much harder to hit the high pin densities required these days.

The problem with the 360 was bad thermal management causing the solder to melt - using PGA wouldn't have helped that any.

oh it would have definitely helped. There is literally no direct metal-to-metal contact with some of the balls on a bga. In the real world, when you place a bga part onto a bga pattern of pads on a pc board, only a few of the balls are actually making physical contact with the pads. Those are the balls that stick down the furthest. The rest of the balls are floating just a few nanometers (or more) above the pad. When the board is run through the solder machine, the solder flows in and fills in these nanoscale size voids and completes the electrical connection. But make no mistake, solder, even a few nanometers of it, is no replacement for a good copper conducter forced into a copper socket at x psi. You want conductor on conducter contact, in 3 dimensions, whenever possible. A ball on a flat pad is a recipe for disaster. But they are cheap, especially when you expand out to 1100+ pin arrays. If you dont use bga, in some cases you could be paying more for the packaging than what is inside it. So we are basically stuck with bga. (Until it is replaced by something even cheaper and most likely even less reliable.)

 

[Joseph F]

If pin density is an issue then they could use LGA but that would be bat$#!7 insanely expensive AFAIK.