PCB Design Blogs

If you think embedding components in a PCB just reduces product size, well that's true but that's only half the truth. Embedding components also increases performance and reduces transmission loss. So it's about miniaturization and performance with enhanced integrity too. Of course, it is obvious when you think about what embedding actually means. Instead of placing components only on the top and bottom layers, you embed some components in the inner layers. The components can be active or passive. If you are designing a high-speed device and worrying about size, parasitic inductance, and so on and so forth, embedded components is definitely an option for you. Worry not for the technology is widely supported by fab houses. 

Once you decide to embed your components, where do you start? What's the first task you do? I suggest you start early, very early, and get in touch with your fabricator to ensure proper parameter and constraint settings to match their process flow. As for what all you will end up doing or need support from your EDA applications, I list below.

Step 1: Mark the Embedded Components

If you decide early that you are going the embedded component way and know which components you will put in the inner layers, I suggest you mark these components as such in your schematic tool itself. Use a schematic editor that allows you to identify the components and also to give your PCB designers enough options to decide when possible. For example, you might specify a few components as 'must embed' and a few as 'if possible, embed'. 

But it's your choice after all and you might want to mark your components during PCB design. Your layout editor must support that too. You should be able to mark embedded components through constraints, component properties, or drawing properties. And, if you marked them in the schematic editor, the marks better flow through to the layout editor.

Step 2: Set Up the Layers 

The next step is almost obvious. You mark the inner layers where you will embed the components. So, what all should the design application let you do? It must let you specify the inner layers where your components can be embedded. You should also be able to specify the direction in which the component extends. That brings us to another requirement because of course components will extend and some will be thicker than the layer. You must have a way of allowing the component to protrude into adjacent layers.

That does it for us almost. Except that you will definitely want to specify how the component is attached to the layer, its orientation. Yes, the application must support that too.

Step 3: Place the Components

When you normally place your components, the application knows where they are going. But with embedded components, you must tell the application. So, there must be at least a manual method of specifying the layers. That will suffice for the interactive placement. What about automatic placement? You will definitely want that to be possible too. 

It's quite simple if the application you use has the right options, no doubt.

Conclusion

Maybe that looks too simple and you are asking, "Wait, what about cavities?" Yes, you must have sufficient support to be able to handle not only how and where you place the components and in what orientation but you need support for cavities too. For that matter, you will need quite a few special templates to handle the embedded 'class' of objects.  

You might not ask (or might), but yes, the application must support ways to define various special properties around embedded objects. For example, to specify the minimum spacing between edges of a cavity before a merge can take place. Or, the height of via used to connect indirectly attached components. 

Well, well, you will need some checks too. Now, that I have mentioned cavities, the 'holes', if I may say so, that will actually hold the components, will you not want to check the cavities are the right size? Or, for that matter, specify how many components can be put together in one cavity? Yes, your application must have a few useful embedded component constraints too.

Like I always say, it is good to talk the talk but how about walking it too? Well, if you are interested and want to try out right away, I will suggest you try your hands on the sample database attached to the Rapid Action Kit (RAK) on Embedded Components at Cadence Online Support. The RAK has step by step explanation of the complete flow starting with marking your embedded components in a schematic editor or a layout editor, setting up the layout, placing components, to setting up the parameters and constraints. As a bonus, you will get to know about using dual-sided contact components too. You will, of course, need a valid Cadence ID to access the RAK.