PCB industry's u-turn trend from
multi-layer to double or even single layer
Before the birth of microprocessor, semiconductor chips
hardly had more than 24 pins. With the birth of microprocessor
and the PC, the complexity of address bus and data bus running
on the PCB boards has grown phenomenally with number of
stacked connection layers on PCB increasing to 20+. The
64 bit and 32 bit address/data lines on a typical PC motherboard
PCB looks like roots of a tree, with only difference of
former being parallel. It's Herculean task to trace a connection
on today's multi-layer PCBs.
The big question is, does this trend of growing PCB complexities
going to continue? If we study few of new technologies coming
up in the market, the trend may be that of opposite type.
The simple answer for this reverse trend can be System
on Chip (SOC). The semiconductor vendor of SoC class ICs
would be packing up all the necessary semiconductor devices
in single chip. It can be monolithic or a multi chip module.
Also there is serious research going on to develop chip-to-chip
communication through optical channels so that the data
and address is multiplexed and sent on a single optical
wire. Intel has demonstrated integrated photo diode inside
a chip from silicon material.
With this kind of technology, the Printed Circuit Board
will have one or two SoC class devices, couple of power
semiconductor devices, and few passive and electromechanical
components. The connection between these devices is hardly
any complex, with only two layer or a maximum of 4-layer
PCB is suffice.
However its not that easy to develop SoC class chips for
every application. Huge volume requirement only can be meaning
full for companies to invest in SoC development.
The precision and reliability required for industrial, medical,
and such fields still not feasible through SoC type devices.
For low volume, customized, requirement the discrete semiconductor
ICs are only the way for many more years.
But when it comes to mass consumer, otherwise called convergence
market, the next level of integration in VLSI design may
reduce the PCB complexities back to layer2 or layer 4 levels
or even to layer 1 level.
There are already few new mobile phone ICs released in
the market, which says these devices need only 2 /4 layer
This trend is a welcome trend, if we look into the environmental
hazards caused by chemical wastage produced by PCB industry.
With the reduction in PCB size and layers, some amount of
Copper metal is also saved.
Year 2009 and 2010 might see some unexpected trends such
as these to give different market dynamics to ailing electronic
industry for a positive change. But for the PCB industry,
this trend should be carefully watched to save them from
factory expansion/ technology up gradation.