Do any SOI tricks work on PCBs?

[MadRat]

SOI is better because it runs cooler and faster than the comparable standard microcircuitry. Is there any way to use the tricks of SOI to improve mainboards and peripherals made on PCBs?

 

[rimshaker]

SOI technology doesn't apply to PCB's. It's like talking about apples and oranges. Circuit boards are a certain product and material, and silicon wafers are another.

 

[MadRat]

But a 15% increase in transmission speed would not help??

I was also thinking the reduced usage of electricity will be key in the next few years. We are probably going to want to market the running costs of PCs soon.

Water pumps were once only advertised by their power output. Then one day someone had the bright idea to advertise running costs against the competition, namely because their lightweigth parts ran much more efficient than the heavier parts in the competitors design. A $5 a month difference makes $60 a year, and $300 every 5 years barring a stagnation of energy prices.

The idea caught the idea of some Democrats and soon we had the idea introduced into bills. This cost of ownership from running costs is a sizeable chunk of change. Nowadays just about every major appliance is mandated to show cost of ownership due to government regulations. Its probably a matter of time before the individual parts of PC's have to be measured, too!

 

[Semimaker]

SOI is only concerend with the junction of the transistor at very small feature sizes.

This will in NO way effect a PCB. Remember that silicon is a semiconductor, PCB is not.

 

[MadRat]

Yeah, I think I see what you're saying. PCB doesn't leak voltage like silicon, right? So basically the SOI process makes it run faster because the electrons go where they are supposed to go, not because they move necessarily faster.

 

[zephyrprime]

<< PCB doesn't leak voltage like silicon, right? >>


Yeah. In some sense, PCB are already "COI" - copper on insulator. PCBs are made of fiber glass and fiber glass certainly is an electrical insulator. They only need SOI for silicon because silicon is a semiconductor.

 

[rimshaker]

<< Yeah, I think I see what you're saying. PCB doesn't leak voltage like silicon, right? So basically the SOI process makes it run faster because the electrons go where they are supposed to go, not because they move necessarily faster. >>



The main performance feature of SOI is that it greatly reduces the capacitance between a transistor and the silicon body. This allows the transistor to switch faster. There are many other features, but this is the big one.

 

[Mark R]

In some specialist systems, special PCB materials (e.g. PTFE) are used to provide a required capacitance or characteristic impedance of critical signal paths. This is typically reserved for especially critical high RF or microwave frequency circuits, e.g. mobile phone transceiver module.

 

[zephyrprime]

Wouldn't the primary source of capacitance on a PCB be due to neighboring wires?

 

[L3Guy]

<< Wouldn't the primary source of capacitance on a PCB be due to neighboring wires? >>


In high RF situations, there is a ground plane on the PC board, either on the back, or one of the layers.
If you keep the traces the right width, and the right distance from the ground plane of the right material and properties, the major capacitance is to the ground plane, not other traces.

I remember some talk at Moto of a PC board material called epsilon 10. Granted, this was 20 years ago, but it was then an exotic PC board material that they considered for some of the RF sections.

Doug