Reading time ( words)
Several defects that are related to the desmear process are presented in this month’s Trouble in Your Tank.
Inadequate or excessive desmear will lead to several PTH defects and failures. Resin smear, ineffective texturing of the resin, and even overly aggressive desmear will contribute to poor plating, adhesion failures and a myriad of other non-conforming defects. However, proper troubleshooting protocol dictates that the engineer also looks at drilling as the contributor to these and other defects. As an example, drilling can cause torn out glass bundles, extremely rough hole walls as well as excessive smear. Poor drill practice may also lead to wedging at the B-stage-to-copper foil interface. These are just a few of the defects that are presented in this column.
Root cause of these defects and the subsequent effect on PTH quality and reliability are also presented.
1. Excessive Etchback
Description: Excessive glass and excessive positive etchback.
Characteristics: Can lead to plating folds, barrel cracking, glass voids, and uneven copper plating in the holes.
a) Temperatures of the solvent and permanganate steps are too high.
b) Dwell times in the solvent and permanganate steps are too long.
c) Concentrations of the solvent and/or permanganate steps are too high.
d) Excessive in feed rates (too high of a chip load in drilling).
e) Drill is punching its way through the stack.
To read the full version of this column which appeared in the May 2017 issue of The PCB Magazine, click here.
Pete Starkey, I-Connect007
With his knowledgeable insight into the business and technology of the printed circuit industry, Dr. Shiuh-Kao Chiang, managing partner at Prismark Partners, has put a global perspective on the challenges of the 2022 PCB market. His presentation at the EIPC Summer Conference in Orebro, Sweden, on June 14 was eagerly awaited by an attentive audience, keen to share his vision. From his comments, it was clear that 2022 will be an interesting year and does not appear particularly friendly for the PCB business.
Chris Mitchell, IPC Vice President of Global Government Relations
The recent surge in COVID cases provoked more than a few questions about what to expect at this year’s IPC APEX EXPO. But as I traversed the San Diego Convention Center last week, the top answer was clear: a lot of smiles! Sure, they were hidden behind masks, but they were evident in the eyes of everyone I met. Attendees were thrilled to be back together in person, sharing ideas as freely as elbow bumps. IPC is a community, and APEX EXPO is the place where we build it.
Mark Goodwin, Ventec International Group
Demand for copper foil is increasing from both PCB and battery production for e-mobility, leading to an upward price pressure for copper foils as post lockdown pent-up demand starts to exceed capacity. Lead times are stretching and prices increasing, particularly for heavy copper foils (2 oz./70 micron and above) as capacity is repurposed to maximize square-meter output for lightweight foils to increase capacity for lithium battery production.