Root Cause of Failures in PWB Lamination


Reading time ( words)

Introduction

Understanding the interactions of the materials, oxide treatment, and the lamination process will help you get to the root cause failures in multilayer fabrication.

When troubleshooting multilayer defects, it is necessary to again understand the effect certain process parameters have on quality and reliability. Truly, the quality of a multilayer printed circuit board (prior to desmear/metallization) will depend on several factors that will now be presented.  

Interlaminar Bond Strength

There are several quality aspects of a multilayer PCB that should be measured on a regular basis. One key determinant of the reliability of the multilayer package is the interlaminar bond strength. The interlaminar bond strength is the strength of the heat-resistant bond between the pre-preg and the copper foil. Ideally, one strives for optimum resin flow encapsulation of the pre-preg with the treated copper innerlayer. The stronger the bond between the pre-preg and treated copper, the lower the chance of delamination. Figure 1 shows an example of delamination. In general, heat excursions increased the stress within the bond and that will lead to failures. So the bond between the copper and the resin needs to be as robust as possible.

The simple definition of delamination is, “a separation between plies within a base material, between a base material and a conductive foil, or any other planar separation within a printed board.” Again, we are referring to a separation. (More on blister and laminate voids in another column.)  It is a huge concern that separation of the pre-preg from the copper foil is often misinterpreted for a blister. Indeed it is more serious than that. As an example, higher temperature resin systems may require more adjustments to the printed circuit processes such as: lamination cycle, baking, hole cleaning, drilling and routing. Polyimide resin and cyanate ester are the most commonly used high-temperature resin systems. These resins have Tgs in the 250°C range.

Read the full column here.


Editor's Note: This column originally appeared in the September 2014 issue of The PCB Magazine.

Share




Suggested Items

Korf and Strubbe: Material Witnesses

10/03/2022 | I-Connect007 Editorial Team
Recently, columnist Dana Korf has been working with Taiwan Union Technology Corporation (TUC), one of the largest providers of copper-clad laminate and mass lamination services in the world. We spoke with Dana about the trends he sees in materials at TUC and around the globe, why copper is still king, as well as some potential non-traditional materials that may see growth soon. Dana invited John Strubbe, TUC VP of technology, to join in the conversation.

The New World Order of JIC

09/27/2022 | Dan Beaulieu, D.B. Management Group
The great business thought leader Margaret Heffernan commented that we are changing from just-in-time (JIT) to just-in-case (JIC). As we’ve worked our way through the issues of the past two years, the world is changing from a complicated to a complex system, and we must be prepared to face the challenges it brings. To survive today, we need the JIC mentality. We must be prepared for the unexpected. No longer can we rely on cycles and patterns to predict the future, or what we might be able to handle based on what that future brings. Now we must prepare for the unexpected. We must be flexible and able to adapt to whatever comes our way.

Pricing Strategies With Michael Carano

09/13/2022 | I-Connect007 Editorial Team
We recently spoke with longtime I-Connect007 columnist Michael Carano, vice president of quality at Averatek, about pricing strategies for PCB fabricators. We’re seeing some movement in this segment as fabricators, already dealing with some of the tightest profit margins around, find themselves having to either raise their prices or trying to massage more revenue out of their already streamlined processes. We asked Michael for some pricing strategies for fabricators, and he shared a range of options for today’s manufacturers who aren’t afraid to rethink their processes and try new ideas. And, as he says, people will still pay good money for a quality, reliable PCB.



Copyright © 2022 I-Connect007 | IPC Publishing Group Inc. All rights reserved.