Look at the packages of the chips which are present on your i,
on your PCB of your iPhone or your iPad. One thing you
will never find no matter how hard you look is these old packaging technology.
So you never find the chips soldered with a QFP package or you will
never see any chips solder, any solder lines any
pins or any solders coming out of these chips.
Because most of these chips nowadays use these ball grid array.
So if you want to really see how they're connected
to you know, how this microprocessor in this case.
these other chips are connected to the PCB.
You really need to flip this, not flip,
but you know, turn it around, turn, look sideways
into it.
So what I've shown here is this side view of this PCB, so now,
now this is, this is my PCB which is made of this organic material.
And now I have these chips, and I can see that these chips and it's dual
sided PCB chip with chips on this first side, and I have chips on the second side.
And they are connected to my PCB using these ball
grids array.
So this is the bottom view of the chip,
and what I'm seeing here is, is the side view.
And I can see this this chip is now
connected to my PCB using these small balls of solder.
And this is for the, on the chip on the top
side, and this is for the chip on the bottom side.
And while this has been awesome for,
you know, enabling these tiny PCB.
One thing they make, one, I mean one thing I don't like
about them is, they make life miserable for people who do electronic themselves.
So people, DIY folks, who you know, want to build stuff or fix stuff.
It's really a pain in the neck trying to if you
try to if you try to solder a chip with this
BGA package into your into your into your iPhone.
For, personally I had an incident where you know, one of the, one of the
chips on my cellphone had gone bad because I had dropped it, in the toilet.
So I, so, it's, it's, it's embarrassing so you don't mention it to anybody else.
But, so, I spent a week trying to figure out
the where the chip had gone bad and I tried
to identify the, you know that, the the, the,
you know, the pin, a couple of pins which
had the short, a couple of solder balls which
had shorted because of that unfortunate event in the bathroom.
But, you know, I could not fix it myself, because you
essentially need, you need, you need quite advanced piece of equipment.
It's almost like a lithography tools that you need to masking tools that you
need to place solder on these ball grid array and solder it back.
So that's one down side of moving to advanced packaging.
So here's some
food of thought
looking at this bottom picture of the chip.
So we notice that most of these ball grids, all these ball or solder balls are
located in the periphery of this of this of this center region.
So why is that?
Why are these balls located just in the periphery but
they're not located in the center? The reason for that is
that the way this IC is mounted inside this packet.
So you have these, this nice packet which has these balls below it.
But inside package, the way the chip is mounted,
probably is that there is a chip which is mounted,
placed here in the center. And then you have a lot of wire bond,
which are essentially connect, taking the connections from this silicon chip and
connecting it back to this to this package of the chip.
And that indicates that there's a presence of wire bonding inside, going
on inside that's why there are wire burn inside on the other side
which are connecting these the silicon IC
to this package outside. And you again, then
you tend to get limited so, this is the you know, the traditional
ball grid package design where you
have these wire bonds. So, again, you get limited by
limited down by these the, these wire bonds.
So a more, a more recent version of that is this flip chip ball grid area.
And what happens is this design, is that you have this this okay in this
package with these solder balls you know. But instead of now using this wire bond,
you essentially flip this chip around.
So you have the other silicon chip, and you have
a much smaller solder solder soldering connection here, which are also known as
micro-bumps, because, you know, the dimensions
for these are in the micron scale.
And these are, essentially connecting the silicon chips.
So this chip is now flipped over, so the connections are on
the bottom side, and these, they're using the micro-bumps to now connect
to this package, which connects it to the outside world.
And, so, in this flip chip ball grid array package, you would, you can have,
you can expect ball which are placed
right regularly throughout the bottom of your chip.
I want to summarize here by giving you
a timeline of evolution of this different packaging technology.
And so,
I'm summarizing here the different points in time at
which these packages were introduced, going all the way back to this dual
dual-pin package where you had pins on just two sides.
Which is still, by the way, still used by hobbyists or in, in digital laboratories,
for teaching all around the world. And then some of you are already
familiar with this quadruple flat package and it's
still used in a lot of hobby electronics, and a
lot of student projects. and
and then around late 80's were introduced these
pin grid array packages, which were precursors to
these ball grid array packages. And you can still find some of the early
Pentiums used to use these pin grid
array package where you would have these 2D array of pins which would fit
into your motherboard. And then more recently the
industry moved to this ball grid array packages
the first generation of, which was using these wire bonds.
This wire bond ball grid array packages where you would have
these wire bonds connecting your chip your silicon to your package.
And you will have this array of
solder balls which would then connect this package to the
outside world.
And so this was the late you know, late to mid 90s.
And then as we talked about more recently, what people are using most commonly
is this flip chip ball grid array package where you would, flip your chip around.
And now you have these micro-bump technology,
which is connecting your directly your silicon to this package,
which is now, then connected to this outside world using this ball grid array.
And what you see now is like you know, think about, think about how it evolved
from here, 1970's to to the 2000's.
You had maybe four or
five changes.
What you see now is there are so many changes on the horizon here.
So, we will talk about a few of those.
So we will touch upon the 2.5D or
the interposer technology in the, in the next few videos.
We'll, I'll also talk in detail about 3D
IC technology, which is on the horizon there.
And you can see, there, there, you know, there are so many acronyms here.
But you know, we'll try to touch upon some of
the major ones and and describe those in more detail.