© PCB | June 04, 2013

Journey to the center of the ….PCB

The 01005 package, or for the metrically minded of us 0402M, has already been in use since 2001/2002. Although it is a big step down in miniaturization, it will hardly be designed into any of your devices.
Only recently have we started to see the latest (mobile) devices being populated with this package, 10 years after its introduction. However, it has already been in mass production in the IC packaging industry, where 01005 components have been integrated into ICs since 2002.

With 01005 components finding their way onto PCBs, what next? Even smaller components? Passive manufacturers are indeed looking at 0201M (0050025) components, along with many more possibilities like wafer level packaging an imprinting into PCBs. For components, the next step has already been taken: embedded components.

How quickly will they be adopted by the industry and why consider doing this anyway?

Why embedded components?

The why is probably simpler than the how, for a number of reasons. It saves space on the PCB, so can be used to pack in new features or just make the PCB smaller to reduce costs. Integrating can also make devices thinner, which will come in handy for future smartphone designs.

The latest Embedded Passive Devices (EPDs) also no longer have tin leads. The leads are copper, and they are not soldered. That improves signal integrity. Devices can now be faster,and the copper-to-copper connections are much more reliably than soldered leads. And Embedded devices are fully encapsulated, so the end product can withstand muck more severe conditions and comply better with new safety standards and stress tests. The embedding is not just limited to passives (capacitors and resistors), but also for active devices like flip chips (Embedded Active Device, EADs).

So, why would you not want to switch over? You gain better signals and thinner, more reliable products. It does involve substrate manufacturing, though: an industry that does not yet fully incorporate SMT equipment.

There are many ways to embed components. You can place them on a layer and then build layers around the component. Or you can produce the layer and then place the component in very small cavities (the space around the passives is 20 microns or less), then place the next layer on top (making the electrical connections using vias). Here, you are not only dealing with your everyday 01005 or 0201 components (which already give many headaches), but the EPDs are extra low in height.

That again allows thinner devices, but it requires much more delicate handling. And how will the industries shift? Will PCB manufacturing shift towards the SMT industry, or vice versa?

When embedded components?

Clearly, we are not yet ready for everyday manufacturing. But is manufacturing actually in progress? Yes, in the IC packaging industry again, where many processes are done in-house.

The results is faster and thinner IC packaging. You will find large substrates with way over 1500 circuits, supported by a very stiff frame. That all fits on a complete substrate with up to more like 30'000 components extra-thin resistors and capacitors placed in very narrow cavities. Here particularly, as you can imagine, yield counts. But it is being done right now: by SMT equipment, at full speed and with excellent yields.

Just like the 01005 components that are only now slowly finding their way into standard PCB assembly, the embedded device process will probably not show up in standard production for a few years. Will it take another 10 years, though? Or will its benefits persuade some industries to pick it up much earlier.
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