-
- News
- Books
Featured Books
- design007 Magazine
Latest Issues
Current IssueOpportunities and Challenges
In this issue, our expert contributors discuss the many opportunities and challenges in the PCB design community, and what can be done to grow the numbers of PCB designers—and design instructors.
Embedded Design Techniques
Our expert contributors provide the knowledge this month that designers need to be aware of to make intelligent, educated decisions about embedded design. Many design and manufacturing hurdles can trip up designers who are new to this technology.
Manufacturing Know-how
For this issue, we asked our expert contributors to share their thoughts on the absolute “must-know” aspects of fab, assembly and test that all designers should understand. In the end, we’re all in this together.
- Articles
- Columns
Search Console
- Links
- Events
||| MENU - design007 Magazine
Lightning Speed Laminates: Impact of Final Plated Finish on PCB Loss
November 4, 2015 | John Coonrod, Rogers CorporationEstimated reading time: 1 minute
A variety of plated finishes are used in the PCB industry. Depending on the circuit construction and other variables, the plated finish can cause an increase in PCB insertion loss. The plated finish used on the outer ground planes of a stripline circuit have minimal or no impact on insertion loss. However, microstrip or grounded coplanar waveguide circuits, which are common on the outer layers of multilayer high-frequency PCBs, can be impacted by the plated finish for increasing the insertion loss.
In multiple experiments, comparisons were done between circuits with bare copper and circuits with different plated finishes. The bare copper circuits were used for reference only and the circuit structure was a microstrip transmission line circuit using substrates of different thickness.
The reason that most plated finishes cause increased insertion loss as compared to bare copper is that most plated finish are less conductive than copper. Electroless nickel/immersion gold (ENIG) is a very good finish. However, the simple fact is that nickel is about one-third the conductivity of copper, and a circuit with ENIG will have more insertion loss than the same circuit with bare copper. There are several variables concerning how much difference in insertion loss to expect and one of them is the substrate thickness. A substrate that is relatively thin will be more influenced by the conductor effects regarding insertion loss and the added plated finish will add to the conductor losses more for thin circuits than thick circuits. Conductor loss is one component of insertion loss.
A microstrip transmission line circuit is a simple structure with a signal conductor on the top layer and a ground plane beneath that layer. The microstrip transmission line circuit primarily has electric fields between the signal plane and ground plane, but there is a concentration of fields at the edges of the signal conductor. It is at the edges where the addition of the plated finish can increase the conductor loss, which will increase the insertion loss.
One experiment showed the difference in insertion loss of a microstrip transmission line circuit using bare copper and ENIG, but with different substrate thickness. It was found that the thinner circuits had a larger difference in insertion loss when comparing the circuits with bare copper to circuits with ENIG plated finish.
To read this entire article, which appeared in the October 2015 issue of The PCB Design Magazine, click here.
Suggested Items
Trouble in Your Tank: Supporting IC Substrates and Advanced Packaging, Part 5
03/19/2024 | Michael Carano -- Column: Trouble in Your TankDirect metallization systems based on conductive graphite or carbon dispersion are quickly gaining acceptance worldwide. Indeed, the environmental and productivity gains one can achieve with these processes are outstanding. In today’s highly competitive and litigious environment, direct metallization reduces costs associated with compliance, waste treatment, and legal issues related to chemical exposure. What makes these processes leaders in the direct metallization space?
AT&S Shines with Purest Copper on World Recycling Day
03/18/2024 | AT&SThe Styrian microelectronics specialist AT&S is taking World Recycling Day as an opportunity to review the progress that has been made in recent months at its sites around the world in terms of the efficient use of resources:
Matrix to Exhibit at IPC APEX EXPO 2024 in Anaheim, CA
03/05/2024 | MatrixMatrix will be exhibiting at IPC APEX EXPO 2024, to be held on April 9-12, 2024, at the Anaheim Convention Center, Anaheim, CA.
The Chemical Connection: Getting to Know Your Vendor
02/16/2024 | Don Ball -- Column: The Chemical ConnectionAfter working for a capital equipment supplier for almost 50 years, I’ve found that the most important part of getting to know your vendor is good communication among all parties. While contact between fabricators of a constantly changing product line and the designers of those products may occur daily or weekly, conversations between you and your equipment supplier may be years apart. That lengthy gap often means that previous contacts may have been promoted, retired, or moved on to other opportunities. You may have also migrated to a new supplier with whom you have little or no history. In either case, you will be interacting with someone you are unfamiliar with (as they are with you). Therefore, it is essential for both sides to communicate clearly so expectations will align.
EIPC Winter Conference 2024, Day 2: A Closer Look at Global Trends
02/14/2024 | Pete Starkey, I-Connect007The opening session of the second day’s conference proceedings focused on global PCB trends and was introduced and moderated by Dr. Michele Stampanoni, vice president of strategic sales and business development at Cicor Group in Switzerland. He opened the session with Dr. Hayao Nakahara’s knowledgeable and enlightening video presentation on the IC substrates industry.