PCB Designers Notebook: Embedding Components, Part 2


Reading time ( words)

Note: Part 1 of this column appeared in the June 2017 issue of The PCB Magazine.

Technology and processes for embedding capacitor and inductor elements rely on several unique methodologies. Regarding providing capacitor functions, IPC-4821 defines two methodologies for forming capacitor elements within the PCB structure: laminate-based (copper-dielectric-copper) or planar process and non-laminate process using deposited dielectric materials.

Distributed (planar) capacitors

Considered the simplest solution and commonly used to replace discrete power supply decoupling capacitors the planar capacitors utilize closely spaced power and ground planes separated by a thin dielectric layer. The dielectric can be a layer of the glass-reinforced epoxy material, a thin layer of non-reinforced polymer, or a polymer sheet material filled with ceramic powder. This technique will provide significant capacitance and delivers very low inductance. The capacitance range for planar capacitors is 1pF to 1mF, dependent on the dielectric constant, material thickness and area.

Because the planar capacitance is proportional to the dielectric thickness between the power and ground planes, thin dielectrics are preferred. This will increase planar capacitance while reducing planar spreading inductance and minimizes overall board thickness. The reduction of planar spreading inductance also results in a lowering the impedance path while increasing the effectiveness of discrete capacitances.

The total capacitance of the power and ground pair is determined by the effective common (overlapping) area of the copper electrodes. This area, times the capacitance density, represents the total capacitance.

To read this entire article, which appeared in the June 2017 issue of The PCB Design Magazine, click here.

Share


Suggested Items

Julie Ellis: TTM’s Interface Between Designer and Fabricator

04/04/2018 | Barry Matties, Publisher, I-Connect007
As a field application engineer for TTM, Julie Ellis sees the problems that can occur between circuit board designers and manufacturers. Barry Matties spoke with Julie at the AltiumLive event in Munich about the age-old problem of throwing designs “over the wall,” the trend towards HDI, and what advice she would give new designers.

South African Electronics Industry Going Strong

04/03/2018 | Barry Matties, I-Connect007
EDA Technologies is a South African company that offers PCB design engineering services, mainly for the domestic electronics market, which makes up a surprising 12.5% of South Africa’s GDP. Barry Matties recently spoke to founder Nechan Naicker about the benefits of outsourcing to South Africa, the market segments they service there, and any advice he had to offer from his 20+ years in the industry.

Part 2: EIPC’s 2018 Winter Conference in Lyon, Review of Day 1

02/19/2018 | Pete Starkey, I-Connect007
We continue with the rest of Pete Starkey’s report on Day 1 of the EIPC Winter Conference in Lyon, France. Included in this segment are presentations by Ventec, Ericsson, TTM and others, plus photos of their evening tour of Alstom.



Copyright © 2018 I-Connect007. All rights reserved.