SMTA International Conference Proceedings

Laser Exfoliation Removal of Conformal Coatings from CCA PCB Pad Surfaces

Authors: Norman J. Armendariz, Ph.D., Cristian Porneala, Ph.D.
Company: Raytheon Co., IPG Photonics Corp.
Date Published: 9/17/2017   Conference: SMTA International

Seika Machinery, Inc.

Abstract: CCAs-circuit card assemblies for military applications require a high level of performance and reliability, and typically undergo a CC-conformal coating process after SMT-surface mount technology assembly to protect the circuit card and attached electrical components from exposure to moisture and harsh environments.

However, certain areas of the CCA or PCB-printed circuit board metallized surfaces are desired to be free of conformal coating and are required to be clean, solderable and electrically / thermally conductive.

Current conformal coating de-masking processes are time consuming and labor intensive. A more cost effective and automated laser-aided exfoliation method was evaluated and successfully demonstrated to remove parylene C conformal coatings from ENIG-plated Cu pads.

The parylene was removed within a precise pad area, and tested to be solderable to enable subsequent wire-soldering and consistent sealant coverage in a cost-effective manner. This paper will discuss the “physics” of laser ablation, laser exfoliation, materials interactions, test and characterization methods used to evaluate and validate the laser-aided removal processes on actual production CCA product.

Key Words: 

Laser Exfoliation, Laser Ablation, Conformal Coating, SMT, PCB, CCA, Parylene, ENIG

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