Elementary, Mr. Watson: Design Data Packages—Circle of Concern or Circle of Influence?
Fresh PCB Concepts: The Power of a Lunch & Learn for PCB Professionals
The Shaughnessy Report: Solving the Data Package Puzzle
Failure Mode: Hole Wall Pullaway
September 16, 2015 | Paul Reid, ConsultantEstimated reading time: 1 minute
Hole wall pullaway (HWPA) is an insidious defect that is not usually a cause of electrical failure. What happens with HWPA is that the copper plating in a plated through-hole (PTH) is pulled away from the dielectric of the drilled hole wall. The hole must not be filled with any sort of a hole fill in order to see HWPA.
There are two distinct types of HWPA: stress-relieving and stress-inducing. In stress-relieving HWPA, the condition appears to distress the PTH, allowing it to survive hundreds or thousands of thermal cycles without failure. In stress-inducing HWPA, the stress appears to greatly increase, causing the PTH to fail in just a few thermal cycles. What we consider a failure is an increase greater than 10% in the overall resistance in the circuit. A crack that partially bridges the copper at the internal interface is enough to cause a failure.
This column is based on my experience in test reliability of interconnect stress test (IST) coupons. I am addressing HWPA that features moderate to severe outgassing. There may be HWPA due to thermal stressing of the board without any significant outgassing, but this type of HWPA is subtle, and it presents as a dark line between the plating and the dielectric of the hole wall. This type of HWPA is rarely detected.
Stress-Relieving HWPA
Stress-relieving is the most common type of HWPA. It appears that the adhesion of copper plating to the dielectric is reduced most likely due to problems with the application of electroless copper plating adhering to the dielectric of the hole wall. At the same time, the adhesion is strong at the copper’s internal interconnection. In fact, experience suggests that the adhesion of the electroless copper is stronger than the copper plating. This process frequently produces strong interconnections to copper inner layers. This condition may result in a hole wall that looks like a stack of forward or backward “Ds” running the length of the hole where the top and the bottom of the “Ds” is at an internal interconnect.
To read this entire article, which appeared in the August 2015 issue of The PCB Design Magazine, click here.
Share on:
Suggested Items
RF PCB Design Tips and Tricks
05/08/2025 | Cherie Litson, EPTAC MIT CID/CID+There are many great books, videos, and information online about designing PCBs for RF circuits. A few of my favorite RF sources are Hans Rosenberg, Stephen Chavez, and Rick Hartley, but there are many more. These PCB design engineers have a very good perspective on what it takes to take an RF design from schematic concept to PCB layout.
Trouble in Your Tank: Causes of Plating Voids, Pre-electroless Copper
05/09/2025 | Michael Carano -- Column: Trouble in Your TankIn the business of printed circuit fabrication, yield-reducing and costly defects can easily catch even the most seasoned engineers and production personnel off guard. In this month’s column, I’ll investigate copper plating voids with their genesis in the pre-plating process steps.
Elephantech: For a Greener Tomorrow
04/16/2025 | Marcy LaRont, PCB007 MagazineNobuhiko Okamoto is the global sales and marketing manager for Elephantech Inc., a Japanese startup with a vision to make electronics more sustainable. The company is developing a metal inkjet technology that can print directly on the substrate and then give it a copper thickness by plating. In this interview, he discusses this novel technology's environmental advantages, as well as its potential benefits for the PCB manufacturing and semiconductor packaging segments.
Trouble in Your Tank: Organic Addition Agents in Electrolytic Copper Plating
04/15/2025 | Michael Carano -- Column: Trouble in Your TankThere are numerous factors at play in the science of electroplating or, as most often called, electrolytic plating. One critical element is the use of organic addition agents and their role in copper plating. The function and use of these chemical compounds will be explored in more detail.
IDTechEx Highlights Recyclable Materials for PCBs
04/10/2025 | IDTechExConventional printed circuit board (PCB) manufacturing is wasteful, harmful to the environment and energy intensive. This can be mitigated by the implementation of new recyclable materials and technologies, which have the potential to revolutionize electronics manufacturing.