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IPC-WP-019, “An Overview on Global Change in Ionic Cleanliness Requirements,” was initially released in August 2017. This document, a white paper, was released to help the industry understand new cleanliness requirements in the G revision of IPC J-STD-001 Requirements for Soldered Electrical and Electronic Assemblies.
Leading up to that time, for many years, vast facets of the industry utilized a requirement of 1.56 µg/cm2 NaCl to determine acceptable cleanliness of printed circuit assemblies. This was conducted using Resistivity of Solvent Extract (ROSE) testing per IPC-TM-650, method 2.3.25.
With the complexity of assemblies increasing and flux chemistries and cleaning solutions changing, the ROSE test—originally developed in the 1970s as a process control method for rosin-based fluxes—was not an adequate test for acceptable levels of ionic residues on the majority of the new flux chemistries. Many datasheets indicate that the new flux chemistries cannot be brought into solution with alcohol or water. The ROSE test is based on spraying/immersing the board into a 75% alcohol/25% deionized water solution. From this information, science tells us that the ROSE test is inadequate in these situations.
A different method or combination of methods for establishing cleanliness of an assembly is needed to provide “objective evidence.” That knowledge and understanding led to a small group of dedicated volunteers who named themselves the “Rhino Team” to look at the requirements of IPC J-STD-001 and make recommendations for change. This team included technical subject matter experts from aerospace, materials, automotive, and commercial companies.
Over the course of several years and presentations to the IPC J-STD-001 task group, new cleanliness requirements were beginning to emerge. The task group determined that a qualified manufacturing process was required for manufacturers of Class 2 and Class 3 products.
The task group quickly realized that industry needed a technical explanation of the requirements and guidance to help with implementation. The task group directed the Rhino Team to develop a white paper before the requirements were put into IPC J-STD-001. After two years of work, there was consensus approval of IPC-WP-019. Unlike a standard, IPC-WP-019 provides the additional explanations, clarifications, knowledge, and/or guidance on the subject of cleaning requirements in preparation for incorporating those cleaning requirements in IPC J-STD-001.
IPC-WP-019 takes the reader through an explanation of cleanliness requirements within Chapter 8 of IPC J-STD-001G. Scenarios are provided to assist the reader with examples of how the requirements can be implemented, and additional references available for guidance.
Eleven months after the release of the original IPC-WP-019, a revision of the white paper was released that aligned to the new cleanliness requirements forming the basis of IPC J-STD-001G Amendment 1. Because of the importance of cleanliness of electronic assemblies, IPC J-STD-001G Amendment 1 would introduce the new cleanliness requirements to industry, and IPC-WP-019A would be there to help companies that wanted to begin implementation.
In 2020, IPC J-STD-001H was released. The revision of this document included changes to the cleanliness section, including additional information on what supporting objective evidence is required when qualifying a manufacturing cleaning process. Supporting objective evidence is test data demonstrating that the performance of the product is not adversely affected in the service environment of Class 2 and Class 3 products. This may include test data from surface insulation resistance (SIR) testing, possibly in combination with ion chromatography (IC), historical evidence demonstrating that residues have not caused failures in service, and electrical testing with power on during extremes of temperature and humidity which represent the end-use environment. These changes prompted the Rhino Team to further revise IPC-WP-019 to ensure the explanations and support to industry would remain current.
Today, IPC-WP-019B continues to support the industry and provide the explanations and information needed to assist companies using the cleanliness requirements of IPC J-STD-001H. It’s the how-to behind the requirements.
For more information or to purchase IPC-WP-019B, visit IPC.org.
Debora Obitz is manager of IPC Technical Programs.
This article appeared in the July 2021 issue of SMT007 Magazine.