Based on a Reddit question, I thought I should address the topic of Embedded components on PCBs. In its simplest form, embedding components is the process of taking any parts like capacitors, resistors, or active ICs which you might place on the top and bottom layers to the inner layers of your PCB. This means that the components are not visible anymore on the outside and you introduce a vertical stacking as a capability.
Why do we need this? One of the primary reasons for using embedded components is to achieve miniaturization. With device sizes shrinking all the time embedding components inside PCBs enables designers to optimize space utilization and reduce the overall footprint. You can potentially reduce the PCB sizes by a factor of 30-70% going with this tech. By placing components very close, the parasitic effects, such as inductance and capacitance, can be minimized, leading to enhanced signal integrity and reduced electromagnetic interference. The components are shielded and sealed within the layers, safeguarding them against moisture, dust, and mechanical stresses making them suitable for harsh operating conditions. For thermal heat dissipation, since it’s sandwiched on all sides, thermal dissipation can also be better.
There are different techniques for manufacturing a board like this. First, you go about choosing the components which will go inside based on the component heights. Components with larger thicknesses are not preferred on the inside. Manufacturing starts with the inner layers and placement of these parts via the normal soldering reflow process, then outer prepreg and resin layers are cut out via laser etching based on the component contours to fit the thickness. Now when they are heated, the resin flows over the components and creates a very strong bond.
The major drawback is cost and eventual repairability is non-existent. Altium and Allegro PCB softwares support embedding components with good mechanical integration and export. There is a good design rule guide worth exploring from Wurth Elektronik on how to go about designing embedded component boards.
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