Oxide Alternative Processes


Reading time ( words)

Introduction

It is all about optimizing the performance of the oxide alternative chemistry. This includes close monitoring of the main reactive ingredients of the process chemistry. And one of the first issues that the industry had to address, whether one is using reduced oxide chemistry or oxide alternatives, is pink ring. While the industry has enjoyed moderate success at minimizing the dreaded pink ring defect with reduced oxides, the desire has long been to simplify the bonding treatment process. Secondly, improving bond strength on high-performance and advanced resin materials is critical to the successful implementation of any interlayer treatment process. While the latter attribute is well documented, the ability of the oxide alternative bonding system to resist pink ring must be established. In all instances, where multilayer PWB test coupons (some fabricated with reduced oxide, others with alternative bonding treatment) were subjected a severe acid test, no pink ring was detected. The coupons were immersed in an aqueous solution of 17% hydrochloric acid for 15 minutes. After removal, the coupons were horizontally ground down to remove the outerlayer pad. Coupons were then inspected under 30x microscope. No pink ring was detected on the coupons fabricated with the organo-metallic (oxide alternative) bonding process. However, the reduced oxide bonding process showed pink ring.

It is important to recognize that the existence of pink ring does not suggest that the PCBs are rejectable. In fact, pink ring is defined in the IPC-600H (acceptability of printed circuit boards) as a process indicator. No evidence exists that pink ring affects functionality. In fact, the presence of pink ring concerns a number of manufacturing processes. The focus of concern should be the quality of the lamination bond, the laminate materials, drilling, desmear metallization processes. As an example, etchback prior to metallization can open up a wedge between the B-stage material and the oxide (or oxide alternative). The wedge defect thus can act as a via allowing acid chemicals to seep in, removing some of the treated copper foil coating leading to the appearance of pink ring.

Read the full column here.


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

Share

Print


Suggested Items

Benchmarking Your Process Engineering

04/29/2021 | I-Connect007 Editorial Team
Mark Thompson has been in bare board fabrication for over 30 years. He is now laying out printed circuit boards at Monsoon Solutions, a high-tech design bureau near Seattle, Washington. With Mark’s extensive hands-on knowledge of PCB manufacturing, he brings a unique perspective to PCB design. In this discussion with the I-Connect007 editorial team, Mark shares what’s important from a process engineer’s point of view, and how to stay on top of evaluating and benchmarking your manufacturing process, along with insights from his new role as a designer.

Isola Releases IS550H Material

04/26/2021 | Nolan Johnson, I-Connect007
Nolan Johnson speaks with Michael Gay of Isola and Chris Hunrath of Insulectro about the release of their new halogen-free, high-thermal reliability material, which they hope fills the gap in the market between epoxies and polyimides.

EIPC Technical Snapshot: Supply Chain and Material Price Pressures

04/26/2021 | Pete Starkey, I-Connect007
EIPC’s seventh Technical Snapshot webinar on April 14 was timely and appropriate. In the context of current supply chain issues and material price pressures facing the PCB industry, particularly in Europe, the EIPC team brought together an outstanding group of experts—each a leading authority in his field—to analyse and comment upon the areas of concern and to respond to questions raised by a capacity audience. As Alun Morgan said, “If you don’t use the European supply chain, you won’t have it anymore!”



Copyright © 2021 I-Connect007. All rights reserved.