Advanced Packaging Means Advanced Routing Issues
January 26, 2023 | Kris Moyer, IPCEstimated reading time: 1 minute
![](https://iconnect007.com/application/files/3716/9086/4312/Kris_Moyer_0123.jpg)
In today’s ever-shrinking world of electronics designs, the use of BGA parts with very fine pitch features is becoming more prevalent. As these fine-pitch BGAs continue to increase in complexity and user I/O (number of balls), the difficulty of finding escape routes and fan-out patterns increases. Additionally, with the shrinking of silicon geometry leading to both smaller channel length and increased signal integrity issues, some of the traditional BGA escape routing techniques will require a revisit and/or adjustment to allow for not only successful fan-out, but also successful functioning of the circuitry of the BGA design.
Historically, BGAs could be routed using traditional full through-via structures, with dog-bone traces off the BGA pad. These BGAs were typically 1.27 mm in pitch and had sufficient clearance between the pads to place a Class 3 Level A via without violating any design rules. Additionally, the feature sizes of these packages were sufficient to fabricate in 1-ounce copper without any issues. With increases in chip complexity and I/O density, most BGA packages are now 1 mm or smaller pitch, with some packages as small as 0.4 mm pitch. With these finer pitch packages, it is no longer possible to use traditional full-thru via structures under the BGA. This, in turn, will require the use of sequential lamination and micro-via structures in order to successfully escape route the BGA. Figure 1 shows a comparison between the package and feature sizes of 484-ball 1 mm pitch BGA (U100) and a 100-ball 0.4 mm pitch BGA (U101).
First, we look at the 1 mm pitch part, then evaluate what it will take to escape all balls to the outside perimeter of the BGA. For this evaluation, we will only consider the use of stacked microvias. Staggered microvias will also work, but require significantly more board area. Additionally, the stackup will assume dual stripline for all internal signal layers.
To read this entire article, which appeared in the January 2023 issue of Design007 Magazine, click here.
Suggested Items
Trouble in Your Tank: Materials for PWB Fabrication—Drillability and Metallization
07/16/2024 | Michael Carano -- Column: Trouble in Your TankLaminate materials are the building blocks on which printed circuit boards are manufactured. Circuit board designers rely on the critical electrical properties of the materials to design the interconnects, and with the drive toward IoT (internet of things), autonomous driving, and virtual and augmented reality, material properties take on a very high level of importance.
Beyond Prepreg: The Glassless ‘Revolution’
06/25/2024 | Marcy LaRont, PCB007 MagazineAs our industry rallies around the call to action for HDI and UHDI, we find unparalleled and myriad laminate options. This abundance is rivaled only by the question surrounding them: Can they measure up to the high technology packaging demands required in our near future? Unsurprisingly, recent developments in FR-4-esque materials for high-speed and high-density designs, as well as newer, glassless technology for replacing traditional glass-impregnated laminates and prepreg, are garnering much interest. I caught up with Alun Morgan, technology ambassador for Ventec International Group, to ask about the impending “glassless revolution” and how it’s poised to solve some of our manufacturing challenges.
Connect the Dots: Designing for Reality—Lamination and Materials
06/19/2024 | Matt Stevenson -- Column: Connect the DotsAs many of you have likely figured out, I am quite passionate about the subject of designing PCBs for the reality of manufacturing. I wrote a book about it and I participate in an I-Connect007 On the Line with… podcast series dedicated to the subject. This companion article will focus on multilayer lamination, keeping the bigger picture in mind: Realistic PCB designs should prioritize manufacturability and reliability of the PCB as well as meet the other design requirements. So, one must account for the production variables associated with individual manufacturing partners.
Day 2: A Full Day at the EIPC Summer Conference
06/19/2024 | Pete Starkey, I-Connect007Editor's note: This is the third and final report from the EIPC Summer Conference. It was a bright and early start to the second day of the 2024 EIPC Summer Conference at the European Space Centre, Noordwijk, The Netherlands, June 4-5. A short journey by bus from the hotel in Leiden and our security passes from the day before got us through the gate and to our seats in the Newton Room for Session 4, “Material Studies,” moderated by Martyn Gaudion.
Looking Into Space: EIPC Summer Conference, Part 2
06/17/2024 | Pete Starkey, I-Connect007“Innovative Development of PCB Technology and Design” was the theme of the second session of the 2024 EIPC Summer Conference, June 4-5, at the European Space Centre, Noordwijk, The Netherlands.