Page 26 - EngineerIT January 2022

ICT – RADIO COMMUNICATION

element spacing set to λ/2, successfully soldering them to a PCB
can be challenging. The main guidelines discussed in this article
of 1) increasing the PCB pad size by 20% larger than the LGA
pins, 2) setting the solder mask aperture to be the same size as
the PCB pads, and 3) designing the solder stencil such that the
ground paddle opening is broken up into smaller apertures that
are similar in size to the pins of the LGA, all contribute to reducing
the effect of PCB manufacturing variances. These guidelines have
been proven to deliver a high yield board assembly consistently
across manufacturing and assembly lots. Having reliable assembly
prevents the need for any PCB rework, which saves money and
decreases time to market. n

Analog Devices is represented in South Africa by Arrow Altech.
For more information email Conrad Coetzee at
ccoetzee@arrow.altech.co.za

About the authors
- Joel Dobler is a staff product applications engineer in the
Aerospace and Defense Group, focusing on beam former
Figure 13: ADAR1000 PCB keep-out regions; silkscreen features are at a products, but also supporting vector modulators and
minimum of 1.85 mm from DUT pads.
programmable low-pass filters. He has worked for Analog
Devices since 2006, supporting a wide range of RF products
designator were moved well outside the 1.85 mm keep-out region. including logarithmic and rms detectors, digital and analog
For the ADAR1000, this minimum keep-out region is 1.795 mm from variable gain amplifiers, mixers and I/Q demodulators. He
the edge of package. If the distance between package edge and pin received his B.S.E.E. from Washington State University in 2005
edge is large, it is recommended to reference the keep-out regions and his M.E.E.E from Portland State University in 2007.
to the package edge, instead of the pin edge as shown in this article. He can be reached at joel.dobler@analog.com.
The ADAR1000 evaluation board allowed for keeping the
nearest components and silkscreen features well away from the - Eamon Nash is the applications director for RF amplifiers and
ADAR1000. This keep-out region is not always possible on planar beam formers at Analog Devices. He has worked at Analog
phased array application boards, but board designers should keep Devices for 30 years in various field and factory roles covering
this guideline in mind when designing their board and observe mixed-signal, precision and RF products. He is currently focused
these guidelines as best as possible. on RF amplifiers and beam former products for satcom and
radar. He holds a Bachelor of Engineering (B.Eng.) degree in
Conclusion electronics from the University of Limerick, Ireland, along with
While LGA packages offer the high pin count density that is required five patents.
in high frequency planar phased array electronics with antenna He can be reached at eamon.nash@analog.com.

Contact Mark Yelland for all your

advertising requirements -

Cell: 074 854-1597 Email: marky@nowmedia.co.za