About 2.5D Technology

NHanced does 2.5D enablement, interposer and chiplet design, 2.5D consultation, manufacturing, assembly, packaging, test, etc.  So, what is that all about?



What is 2.5D?

2.5D – more properly called interposer technology – integrates several electronic devices inside a single package by assembling them side-by-side on a shared base.  The base, an interposer, provides connectivity.

The devices are generally manufactured separately and delivered to the assembly house as bare dies.  The interposer is essentially a large bare die, designed specifically to accommodate those smaller dies.  The interposer contains circuitry to connect the devices to one another and to the outside world, and may incorporate TSVs to carry signals through the interposer substrate.  Some interposers can carry devices on both their upper and lower surfaces.

There may be any number of separate devices on the interposer.  Each may be a standard 2D die, a specialized “chiplet” custom-built for 2.5D assembly, a 3D IC, or any other type of integrated circuit.  The entire assembly is then encapsulated in a single package.  The photo below shows a finished, packaged 2.5D assembly (courtesy of Tezzarn Semiconductor):


The following diagram illustrates the far-ranging possibilities of 2.5D integration (courtesy of Georgia Tech PRC):


What are the Benefits of 2.5D?

In traditional 2D electronic circuits, each die is packaged separately.  The packaged chips are laid out on a circuit board and connected to one another with tiny wires.  A typical circuit board is shown in the photo below:


Compared to this traditional 2D architecture, 2.5D assemblies provide several significant advantages:

Footprint

Devices that share a package take up less space than if they were packaged separately.  Depending on the sizes and requirements of the components, an interposer assembly may be no larger than a traditional 2D chip.  The finished interposer assembly is not as compact as a 3D IC, but it offers appreciable size reduction.

Speed

Devices assembled on an interposer are much closer together than chips on a circuit board.  Although the connections on the interposer are not as miniaturized those in a 3D IC, they are only a fraction of the length of circuit board wires.  Shorter distances allow electronic signals to travel more quickly from one component to another, so a 2.5D assembly can demonstrate higher performance than an equivalent circuit board.

Power

Like 3D ICs, 2.5D assemblies save power by using shorter connections.  Depending on the design of the on-board devices, they may also avoid using ESD (electrostatic discharge) protection between the devices.  ESD protection has a large power budget, so the assembly may consume a great deal less power than an equivalent circuit board.

Heterogeneous Integration

The devices in a 2.5D assembly are manufactured separately, so they can vary widely.  Each device may come from a different supplier, be built in a different process, incorporate different materials, etc.  The components may differ in scale, voltage, dimensions, and any number of requirements; the differences are accommodated by the interposer.

Simplified Integration

Unlike a 3D IC, an interposer assembly can incorporate circuits that were not originally designed to be stacked.  Rather than redesigning all the components, engineers need only design an interposer.

What’s the Catch?

If 2.5D is so great, why isn’t everybody doing it?

Interposer technology is more complex and expensive than traditional 2D, and it’s not quite as powerful as 3D.  It’s somewhere between the two – a fact that inspired the whimsical moniker “2.5D.”

Implementing a 2D circuit board is straightforward, but the result is big and slow.  Building a 3D IC is demanding and difficult, but it produces an extraordinarily small, quick device.  Today’s engineers embrace 2.5D as an elegant, workable compromise between the two.

NHanced manages the entire 2.5D supply chain, from design and procurement through packaging and test.  Are you ready to NHance your product?  Contact us today.