We hear a lot of talk these days about three-dimensional integrated circuits (3D ICs), but there's still a lot of confusion in this area, so who better than yours truly to rip the veils asunder? To set the scene, let's consider the way of the world before 3D ICs.
Lots of small, individually packaged dice
Not so long ago, different functions like high-performance logic, lower-performance logic, memory, and analog/RF were presented as discrete dice in their own chip packages, as illustrated below. (Dice is the accepted plural form of die in the semiconductor industry.)
A bird's-eye view of a circuit board with individually packaged chips.
One advantage of this scenario was that different chip companies could concentrate on creating devices that fell into their realm of expertise. Another benefit was that each die could be implemented at the most appropriate technology node. The high-performance digital logic chip could be created at the latest and greatest (and more expensive) technology node. The lower-performance digital logic device could be created using an earlier (and more affordable) technology node. Yet another advantage was that the yield of smaller silicon chips was significantly higher than that for larger dice.
On the downside, the resulting circuit board was relatively large and heavy and consumed a lot of power. Also, every soldered joint on a circuit board was a potential point of failure. Furthermore, it took a relatively long time for signals to propagate across a circuit board from one chip package to another. This hurt the performance of the system as a whole.
Max Maxfield 7/7/2012 10:50:09 AM User Rank Blogger
Re: the world
@Jason: Let me check with the FPGA companies to see what they say about using SiPs ... sometimes it depends on the terminology -- you or I might say they do, while they might say they don't
@Max: The typical substrate thickness of a single die is 0.8 - 1.0mm. Microprocessors and systems with very fast clock rate (GHz range) have issues with thermal management, and typically require external cooling using devices such as heat sink. I remember seeing a youtube video of an Intel chip smoking within the minute that the heat sink was removed from the microprocessor. I am wondering how good these SiP are at thermal management. More specifically, what are the typical power usage of applications using SiP? Low-power? Some of the consumer electronics that use SiP include mobile phones and MP3 players. So, it may perhaps be inferred that SiP are good for low-power devices. By the way, are any of the FPGA technologies using SiP?
Max Maxfield 7/6/2012 10:14:22 AM User Rank Blogger
Re: the world
@Jason: I believe that the thickness of the individual die are in the order of 0.2mm.
Re the thickness of the substrate, that depends what the substrate is made out of -- SiP Substrates range from ceramic (either a single layer or multiple paper-thin layers with embedded tracks), to silicon to saphire to ... well, all sorts of things, really. But a very common one is a laminate, which you can think of as an ultra-thin printed circuit board using high-density interconnect (HDI) and micro-via technologies.
@Max: Very interesting, comprehensive intro. I like to add the conventional IC, SoC and SiP are arranged in the order of increasing implementation complexity (*obviously*) and cost. Off my mind, I have a main question about SiP. Each die has its own substrate. Most IC are built on silicon substrate. For SiP, there is a common substrate. What is the typical thickness of this common substrate? And, what is the typical substrate thickness for each die on an SiP?
Max Maxfield 7/6/2012 9:15:28 AM User Rank Blogger
Re: the world
@Myplanet: "After 3D..."
Let's get through 3D first -- I have two more 3D articles in mind, plus I'm sure there will be more after that ... and then we'll worry about "after 3D" (grin)
"I wasn't sure whether readers would like one big article or a number of smaller "bite-size" pieces"
Max, I would like to read smaller bites rather than a 3 page article. I think most of the other readers may also have a similar opinion. After 3D, what's going to be next great in development side.
Max Maxfield 7/5/2012 10:50:39 AM User Rank Blogger
Re: the world
@Jacek: Thanks for the feedback -- I wasn't sure whether readers would like one big article or a number of smaller "bite-size" pieces (also I just now discovered how to post multi-part articles (grin)
DIE, n.The singular of "dice." We seldom hear the word, because there is a prohibitory proverb, "Never say die." At long intervals, however, some one says: "The die is cast," which is not true, for it is cut.
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