• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer

Electrical Engineering News and Products

Electronics Engineering Resources, Articles, Forums, Tear Down Videos and Technical Electronics How-To's

  • Products / Components
    • Analog ICs
    • Connectors
    • Microcontrollers
    • Power Electronics
    • Sensors
    • Test and Measurement
    • Wire / Cable
  • Applications
    • Automotive/Transportation
    • Industrial
    • IoT
    • Medical
    • Telecommunications
    • Wearables
    • Wireless
  • Resources
    • DesignFast
    • Digital Issues
    • Engineering Week
    • Oscilloscope Product Finder
    • Podcasts
    • Webinars / Digital Events
    • White Papers
    • Women in Engineering
  • Videos
    • Teschler’s Teardown Videos
    • EE Videos and Interviews
  • Learning Center
    • EE Classrooms
    • Design Guides
      • WiFi & the IOT Design Guide
      • Microcontrollers Design Guide
      • State of the Art Inductors Design Guide
    • FAQs
    • Ebooks / Tech Tips
  • EE Forums
    • EDABoard.com
    • Electro-Tech-Online.com
  • 5G

Going smaller & more portable with PCB embedded components

July 20, 2016 By Chris Francis Leave a Comment

I recently came across the TDK SESUB-PAN-T2541 Bluetooth module. It is a complete bluetooth module consisting of a Texas Instruments CC2541 Bluetooth “System-on-Chip” (SoC) and the peripheral components required to use it – crystal, balun, and 15 other passive components. While it initially doesn’t sound that remarkable, when you look at the size (4.6mm x 5.6mm) and the thickness (1mm) you realize that it is remarkably small. It achieves this feat by embedding the die of a CC2541, which would normally be 6x6mm and 1mm thick when packaged in the PCB. It got me thinking about what other techniques there are around to minimize circuit size, particularly with the current need to make smaller and smaller portable products.

PCB embedded Fig 1

Embedding simple passive components, particularly capacitors, is one way of reducing overall size. Of the passives in the TDK T2541, the majority are decoupling with most of the rest being tuning components. While they are conventional surface mount in this case, another strategy would be to use a conventional IC and embed some passive components. Obviously. the TDK module doesn’t take this approach because the packaged CC2541 is larger than their overall PCB.

The surface area of a PCB is premium space and while you can have more and more inner layers as well as blind and buried vias, the increase in surface area created by those efforts is small. Three-dimensional component construction seems a great idea in theory.

A product I am currently working on has a 144-pin FPGA which requires 34 decoupling capacitors. Depending on the FPGA package and decoupling capacitor package chosen, the decoupling capacitors can take up more space than the FPGA itself. Murata GRU series and AVX UT series capacitors are both intended for embedding within PCB substrates and have copper termination rather than tin in order to facilitate embedding. Both the Murata capacitors and the AVX ones are 0.15mm thick and 1mm x 0.5mm overall. The Murata web site gives an illustration of the area saved by embedding the capacitors:

PCB embedded Fig 2

In reality, you could put decoupling capacitors on the opposite side of the PCB to the chip but in a system with limited space the underside is probably already in use. AVX has a short paper on embedded components although it is uncertain if the document is current as it is undated (but appears to be from 2011). While embedding capacitors is easier than embedding die, if you wanted to go down the route of embedding decoupling capacitors, what is involved?

You need to choose your components based on the manufacturing technique e.g. solder versus copper connections, and you need a PCB manufacturer who can work with the embedded components as they need to be embedded during the PCB fabrication. To avoid problems when soldering the PCB surface components, the embedded components are often chosen with copper electrodes and connected with copper vias. This prevents potential failures from melting solder when soldering the top/bottom components, which could happen if solder was used to connect the embedded components Finding a PCB manufacturer to also place the embedded components will be your first challenge – most PCB manufacturers aren’t set up to place components. Then you need to design the PCB in a way which allows the manufacturing to be carried out, such as creating the inner cavities required. Altium have added support for embedded PCB components in their PCB layout package, allowing the cavities to be defined for active or passive embedded components, for example.

PCB Embedded Fig 3

If your PCB layout package doesn’t support embedded devices you will still be able to design the PCB, it will just require more intervention to create manufacturing data which contains the required information, and accompanying notes and discussions with the PCB manufacturer.

An alternative approach if you are simply looking to add embedded capacitance for decoupling would be to use a PCB material and construction that creates additional power plane capacitance using a thin, high dielectric material for one or more of the PCB layers. 3M have such a material, as do other material manufacturers such as Sanmina, DuPont, and Mitsui. The 3M system uses a 19µm dielectric layer with a dielectric constant of 21 for embedding between the power plane layers instead of FR4 (or other PCB material). It has around 6nF per square inch of capacitance. Other presentations from 3M suggest a dielectric as thin as 6µm with 20nF/in≤ and it seems there is the possibility of materials with dielectric constants in the thousands being available. An Oak-Mitsui presentation provides useful information here:

While 6nF/in≤ doesn’t really seem to provide enough capacitance to decouple a typical FPGA, it could eliminate most of the decoupling capacitors, leaving just a few larger ones which can be placed conventionally. This is the implication from Sanmina which suggests a large reduction in the number of capacitors required with their BC 2000 dielectric core from 48 capacitors to 17 for a 1156 BGA. Presumably, the remaining conventional capacitors are the higher values.

As a result of looking into PCB embedded components I came to the conclusion that while the technology exists and has done for quite a while, it is still rather niche with components and fabricators hard to find. There will also undoubtedly be a cost penalty, so you need to be really certain that is the only way to reduce you system size before you use it, unless your product isn’t price-sensitive.

DesignFast Banner version: 22e7f758

Filed Under: Analog IC Tips, Analog ICs, Embedded, FAQ, Featured, PCB Design Tagged With: basics, FAQ

Reader Interactions

Leave a Reply Cancel reply

You must be logged in to post a comment.

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Primary Sidebar

EE Training Center Classrooms

EE Classrooms

Featured Resources

  • EE World Online Learning Center
  • CUI Devices – CUI Insights Blog
  • EE Classroom: Power Delivery
  • EE Classroom: Building Automation
  • EE Classroom: Aerospace & Defense
  • EE Classroom: Grid Infrastructure
Search Millions of Parts from Thousands of Suppliers.

Search Now!
design fast globle

R&D World Podcasts

R&D 100 Episode 7
See More >

Current Digital Issue

April 2022 Special Edition: Internet of Things Handbook

How to turn off a smart meter the hard way Potential cyber attacks have a lot of people worried thanks to the recent conflict in Ukraine. So it might be appropriate to review what happened when cybersecurity fi rm FireEye’s Mandiant team demonstrated how to infiltrate the network of a North American utility. During this…

Digital Edition Back Issues

Sponsored Content

Positioning in 5G NR – A look at the technology and related test aspects

Radar, NFC, UV Sensors, and Weather Kits are Some of the New RAKwireless Products for IoT

5G Connectors: Enabling the global 5G vision

Control EMI with I-PEX ZenShield™ Connectors

Speed-up time-to-tapeout with the Aprisa digital place-and-route system and Solido Characterization Suite

Siemens Analogue IC Design Simulation Flow

More Sponsored Content >>

RSS Current EDABoard.com discussions

  • Help with Verilog replicate operator
  • ESP Serial Communication Problem with RS232
  • How to mark layer comments in CAP of spef file using StarRC
  • MAX5389 resetting by noise
  • Simulation of resonator in HFSS

RSS Current Electro-Tech-Online.com Discussions

  • Will Header and socket hold this PCB OK?
  • Relaxation oscillator with neon or...
  • software PWM
  • MPlab8 remove page breaks in list file
  • ATOM Diy module

Oscilloscopes Product Finder

Footer

EE World Online

EE WORLD ONLINE NETWORK

  • 5G Technology World
  • Analog IC Tips
  • Battery Power Tips
  • Connector Tips
  • DesignFast
  • EDABoard Forums
  • Electro-Tech-Online Forums
  • Engineer's Garage
  • Microcontroller Tips
  • Power Electronic Tips
  • Sensor Tips
  • Test and Measurement Tips
  • Wire & Cable Tips

EE WORLD ONLINE

  • Subscribe to our newsletter
  • Lee's teardown videos
  • Advertise with us
  • Contact us
  • About Us
Follow us on TwitterAdd us on FacebookConnect with us on LinkedIn Follow us on YouTube Add us on Instagram

Copyright © 2022 · WTWH Media LLC and its licensors. All rights reserved.
The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media.

Privacy Policy