Hello folks. In these next couple of lectures, we'll be
talking about this very fun and evolving and exciting topic of chip packaging.
Or
you know more specifically, IC chip
packaging, or packaging of integrated circuits.
And this is you know a very exciting and evolving field.
So then, this image here, are your
pictures of different packages of chips, so if
you have taken any digital electronics class or if you have done any do it
yourself electronics project, you might, you know, this
images might already be very familiar to you.
This is a dual in line package or Dip package Which is, if
you have done ever inserted chips into a bread board, it's
usually these kind of packages and it's usually these kind of packages
and, for any amateur in electronics you might have already been familiar with
this package which is, Quadruple flat package or QFP so it has chip, it has you
know these pins coming down from all four directions, that's why it's quadruple and
This chip packaging world is full of acronyms three
letter or four letter acronyms defining these different packages.
And so, I won't,
you know boggle with all acronyms which we will talk about a
few of those in the next in the next couple of videos.
So, to give you some historic context this is how
packaging was defined in, you know, in the late 80s or 90s So
this is a definition of packaging taken from a handbook of packaging
back in the late 80s. And, essentially, a package, for a chip
used to have, four major function. And this is still true today.
So it will have four major function.
One would be to distribute power lines, so you know bring in the voltage supply.
And bring in the current required for
the functioning of the chip, distribute the signal,
both coming in and going out of the chip.
Then the next function would be to take out the
heat which is dissipated in this chip and distributed outside.
And the other thing is to, you know, protect your, chip, most importantly
from, earlier it used to be from, you know, from the environment, from the heat.
nowadays it's becoming more about, you know, protect it,
from electromagnetic radiation coming in and so on.
So another way to define packaging would be
that it's a means of connecting features on
your transistors which are in the order of, whose
dimensions are in the order of a few nano-meters.
to features on your package which are on
the order of dimensions of a few millimeters.
So, it's a way to bridge these dimensions from an
nanometer scale to a millimeter scale. So it's a way to bridge these dimensions.
over a six order change in magnitude.
To be very honest, there was not too much action happening in
the field of packaging, back in, you know, until the last decade.
The IC world had become very flat
so it would be, it would function like Jenson Wong from NVIDIA
with designer chip. He would call up Thomarus Chang from TSMC
to fabricate, run these wafer lots for him and make this chips and they will
ship these wafer lots to a packaging house Somewhere in Asia.
In this case Ibiden which is a
big packaging house located in the Philippines.
And they would dice these chips and put them into nice packages.
They will ensure that the sale happens in Philippines so they save on tax.
But, you know, there's not too much action happening in the packaging there.
Which was, you know, had become a very bottom layer in this IC food chain.
So, most of the profits would, you know,
be stored with the design house and, you
know, the place where the chips are manufactured.
And the packaging house will get a very
small share of, you know, the overall action.
But this has been, this has changed quite rapidly in the last last five, six years.
So, packaging nowadays, it's besides that four functions that
I defined earlier, it, it is increasingly seen as a way to improve your overall
system performance. And it's also seen a way
especially in your mobile phone devices and your iphones and your ipads you want,
all these chips to fit in a very small form factor.
So you want essentially all your chips to fit, in a very small
form factor so whenever you heard, hear terms like performance and form factor
immediately dollar signs should start popping up in front of your eyes.
So that's why a lot of action is actually now moving into the field of packaging.
I can name at least 20 start-up companies
which are active in the field of packaging.
Even the bigger companies, they want to play and they
want action of this pie too, so there's a lot
of action happening in the field of packaging, and I'll
touch upon some of that,um, in the next few lectures.
To give you some more context on, how advanced the packagin has become, So this
image show here shows here an old desktop computer that I had bought in 2001.
And shown below here is the guts of this computer, or the motherboard.
And you can see the, the microprocessor.
It has this big fan on the top. you can see
different chips.
soldered together, and you can see this, you know, quadruple package.
And you can see these chips soldered together.
This is a graphics chip from Nvidia, and clearly you can identify the, you know,
the soldering of these different chips. There are some expansion slots here.
So you plug in different cards in here. You can plug in extra memory if you want. And there are other elements like capacitors, the inductors and so on. And nowadays you can fit this entire computer in this
Small PCB which is compared, here I've compared it with the size of a H1 pencil.
So you can fill, you can fit in almost all of the
functionality and processing power and computer power in this small small PCB.
So A large part has, of that, is enabled by the
Moore's law
of, chips, you know, becoming smaller and, faster.
But, there's a major role which has
been played by the packaging technology as well.
So packaging has played a big role in enabling this form factor as well.
So, what I want to show next. Is that these changes in packaging or
these changes in packaging have always been, dictated,
by the increase in the pin count. So, many of you might
remember these, DIP packages which were, you know, still
used by Hobby Electronics or, if you take up,
digital electronic class in the electrical engineering department you'll
be using these kinds of packages.
But there, there's only, in these dual inline packages, if you have pins
on both sides, there's only a certain number of pin count that you can go to.
After that Essentially you need to either, you know, your
pins will start to collapse or it won't function as well.
So to the next evolution of that which some
of you might still have seen are these. Quadruple, flat packages
where you have pins coming out from all four
sides and so that took us even further. That took
us to 200 or up to
250 pins. And on your, if you open up
old old desktop computer you will Still see a lot of chips
which are on, which are of this QFP kind of packages soldered to your motherboard.
So why does the pin count keeps on increasing?
So there are multiple reasons for that, one simple reason is
that as you move From say 8 bits to let's think about,
you know, in term of for microprocessor, you know, microprocessors will move
from 8 bits to 16 bits to 32 bits to 64 bits.
You now need more and more of these pins to communicate with
your memories, if you communicating with your DRAM, you now need, you know.
64 into 2 because each line for each signal you need one
reference line, and you know one ground line and the signal line.
So you need more and
more line, more and more pins to communicate
if you are moving, if you are increasing the
bit size of your microprocessors. Especially if you're moving more
functionality say you are moving more and more functionality into a system on chip,
you again need signals coming in from
more analog chips, like your accelerometer,
your gyroscope in your phone, your .All the, you know, all the analog devices, the signals from those coming into your microprocessor.
And so the pin count you know it has been consistently
increasing and that has driven these changes in
packaging from dual inline package to quadruple flat package
And now what is what is used most commonly, this
ball grid array, or BGA package. And
what that entails is these grid of solder balls which are placed on
on below chip, and you would Put this together,
you would you know flip this and put this on your
PCB and you have these grid, these balls which would be connecting,
it should be routing all your connections from your PCB into
your chip. And esentially you know this so we went
from IOs on two sides to IOs on
all four sides and there's so much you can achieve by just being on the parameter.
And now we are essentially moving to IOs all
over in this area, and as I will show you, it will soon require
moving IOs to, you know, to a 3D in a third dimension very soon.