Let’s get the terminology out of the way. 3D-SiP (System in Package) is a relatively new development in the M2M space. 3D refers to the fact that components are placed on the top layer of the stack (x and y direction) and passive components are also embedded in other layers (the z direction).
The objective is to minimize the size of the module and thereby facilitate the creation of new solutions such as GPS-enabled smart watches.
Employing PCB stacks is not new. In regular 2D architecture, components are only mounted on the top and the other layers are used for the interconnection tracks. When the top stack is very small, it’s impossible to connect all the components. This is realized by drilling vias (high-tech term for very small holes) through the boards, which are copper plated, and the construction is then wave soldered.
In a 3D architecture, there are fewer components on top, but the same or similar interconnections are employed.
Consider the above. Regular module construction involves drilling small holes through the copper foil tracks (red) and the PCB (yellow). Layers are interconnected by copper plating (orange) on the holes of each layer. Telit’s 3D proprietary manufacturing process does not involve drilling or plating, and therefore it is more efficient and eco-friendly, since toxic chemical, water and electricity consumption is reduced.
Other substrates and interconnection techniques can be employed as well. For example, AACMicrotec uses vertically stacked wafer substrates and thin-film deposition for the electrical connections. It’s worth paying a visit to the site to see how it works.
The stated benefits of the 3D architecture are faster transfer of information, less crosstalk, better heat conduction and simplified manufacturing. In addition, because they are smaller and lighter, 3D modules are less affected by mechanical vibration and acceleration.
As far as I could find out only one vendor, Telit is marketing a 3D module. Known as the Jupiter SE880, it’s a GPS solution whose form factor is a mere 4.7 x 4.7 mm (0.185 x 0.185 inch), which means the module could sit comfortably on the finger nail of a small lady’s small finger.
Consider the above. Incredibly small dimensions allow this module to be deployed in GPS-enabled consumer devices such as smart watches.
I talked to Desmond Wong, Telit’s manager of business development and advanced technologies, and learned that Telit and a PCB manufacturer spent over a year developing the technology required to optimize the off-the-die circuitry without drilling holes and copper plate the vias.
Unfortunately I can’t tell you how it works, as Telit wants to protect its investment. But it clearly does work since the SE880 is a shipping product.
Telit had also boosted the GPS performance by using a state-of-the-art RF frontend. Spatially calibrated waveguide-quality radio paths inside the three-dimensional space of its architecture are used to minimize RF noise, which impacts on GPS performance. Enhancing maximum sensitivity in this way enables a much lower TTFF (Time-To-First-Fix) under standard operating conditions: as much as 200 seconds quicker from a cold start.
Enhanced sensitivity also allowed Telit to dispense with the traditional GPS antenna. Instead, the company employs a “printed” antenna that is embedded in the PCB, minimizing the size of the GPS receiver.
Whether the technology comes from AACMicrotec or Telit or another module vendor, this is clearly a groundbreaking development. 3D-SiP opens a new era of performance, footprint reduction and modularization, leading to significant advances in portable electronics.
Edited by Braden Becker